/* Global common subexpression elimination/Partial redundancy elimination
and global constant/copy propagation for GNU compiler.
- Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
+ Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
Free Software Foundation, Inc.
This file is part of GCC.
#include "toplev.h"
#include "rtl.h"
+#include "tree.h"
#include "tm_p.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "ggc.h"
#include "params.h"
#include "cselib.h"
-
+#include "intl.h"
#include "obstack.h"
/* Propagate flow information through back edges and thus enable PRE's
3) Perform copy/constant propagation.
- 4) Perform global cse.
+ 4) Perform global cse using lazy code motion if not optimizing
+ for size, or code hoisting if we are.
5) Perform another pass of copy/constant propagation.
substitutions.
PRE is quite expensive in complicated functions because the DFA can take
- awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
- be modified if one wants to experiment.
+ a while to converge. Hence we only perform one pass. The parameter
+ max-gcse-passes can be modified if one wants to experiment.
**********************
* If we changed any jumps via cprop.
* If we added any labels via edge splitting. */
-
static int run_jump_opt_after_gcse;
/* Bitmaps are normally not included in debugging dumps.
/* An obstack for our working variables. */
static struct obstack gcse_obstack;
-/* Nonzero for each mode that supports (set (reg) (reg)).
- This is trivially true for integer and floating point values.
- It may or may not be true for condition codes. */
-static char can_copy_p[(int) NUM_MACHINE_MODES];
-
-/* Nonzero if can_copy_p has been initialized. */
-static int can_copy_init_p;
-
struct reg_use {rtx reg_rtx; };
/* Hash table of expressions. */
{
struct expr * expr; /* Gcse expression reference for LM. */
rtx pattern; /* Pattern of this mem. */
+ rtx pattern_regs; /* List of registers mentioned by the mem. */
rtx loads; /* INSN list of loads seen. */
rtx stores; /* INSN list of stores seen. */
struct ls_expr * next; /* Next in the list. */
int invalid; /* Invalid for some reason. */
int index; /* If it maps to a bitmap index. */
- int hash_index; /* Index when in a hash table. */
+ unsigned int hash_index; /* Index when in a hash table. */
rtx reaching_reg; /* Register to use when re-writing. */
};
static regset reg_set_bitmap;
/* For each block, a bitmap of registers set in the block.
- This is used by expr_killed_p and compute_transp.
+ This is used by compute_transp.
It is computed during hash table computation and not by compute_sets
as it includes registers added since the last pass (or between cprop and
gcse) and it's currently not easy to realloc sbitmap vectors. */
/* Number of copys propagated. */
static int copy_prop_count;
\f
-/* These variables are used by classic GCSE.
- Normally they'd be defined a bit later, but `rd_gen' needs to
- be declared sooner. */
-
-/* Each block has a bitmap of each type.
- The length of each blocks bitmap is:
-
- max_cuid - for reaching definitions
- n_exprs - for available expressions
-
- Thus we view the bitmaps as 2 dimensional arrays. i.e.
- rd_kill[block_num][cuid_num]
- ae_kill[block_num][expr_num] */
-
-/* For reaching defs */
-static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out;
-
-/* for available exprs */
-static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out;
+/* For available exprs */
+static sbitmap *ae_kill, *ae_gen;
/* Objects of this type are passed around by the null-pointer check
removal routines. */
sbitmap *nonnull_killed;
};
\f
-static void compute_can_copy PARAMS ((void));
-static char *gmalloc PARAMS ((unsigned int));
-static char *grealloc PARAMS ((char *, unsigned int));
-static char *gcse_alloc PARAMS ((unsigned long));
-static void alloc_gcse_mem PARAMS ((rtx));
-static void free_gcse_mem PARAMS ((void));
-static void alloc_reg_set_mem PARAMS ((int));
-static void free_reg_set_mem PARAMS ((void));
-static int get_bitmap_width PARAMS ((int, int, int));
-static void record_one_set PARAMS ((int, rtx));
-static void record_set_info PARAMS ((rtx, rtx, void *));
-static void compute_sets PARAMS ((rtx));
-static void hash_scan_insn PARAMS ((rtx, struct hash_table *, int));
-static void hash_scan_set PARAMS ((rtx, rtx, struct hash_table *));
-static void hash_scan_clobber PARAMS ((rtx, rtx, struct hash_table *));
-static void hash_scan_call PARAMS ((rtx, rtx, struct hash_table *));
-static int want_to_gcse_p PARAMS ((rtx));
-static int oprs_unchanged_p PARAMS ((rtx, rtx, int));
-static int oprs_anticipatable_p PARAMS ((rtx, rtx));
-static int oprs_available_p PARAMS ((rtx, rtx));
-static void insert_expr_in_table PARAMS ((rtx, enum machine_mode, rtx,
- int, int, struct hash_table *));
-static void insert_set_in_table PARAMS ((rtx, rtx, struct hash_table *));
-static unsigned int hash_expr PARAMS ((rtx, enum machine_mode, int *, int));
-static unsigned int hash_expr_1 PARAMS ((rtx, enum machine_mode, int *));
-static unsigned int hash_string_1 PARAMS ((const char *));
-static unsigned int hash_set PARAMS ((int, int));
-static int expr_equiv_p PARAMS ((rtx, rtx));
-static void record_last_reg_set_info PARAMS ((rtx, int));
-static void record_last_mem_set_info PARAMS ((rtx));
-static void record_last_set_info PARAMS ((rtx, rtx, void *));
-static void compute_hash_table PARAMS ((struct hash_table *));
-static void alloc_hash_table PARAMS ((int, struct hash_table *, int));
-static void free_hash_table PARAMS ((struct hash_table *));
-static void compute_hash_table_work PARAMS ((struct hash_table *));
-static void dump_hash_table PARAMS ((FILE *, const char *,
- struct hash_table *));
-static struct expr *lookup_expr PARAMS ((rtx, struct hash_table *));
-static struct expr *lookup_set PARAMS ((unsigned int, struct hash_table *));
-static struct expr *next_set PARAMS ((unsigned int, struct expr *));
-static void reset_opr_set_tables PARAMS ((void));
-static int oprs_not_set_p PARAMS ((rtx, rtx));
-static void mark_call PARAMS ((rtx));
-static void mark_set PARAMS ((rtx, rtx));
-static void mark_clobber PARAMS ((rtx, rtx));
-static void mark_oprs_set PARAMS ((rtx));
-static void alloc_cprop_mem PARAMS ((int, int));
-static void free_cprop_mem PARAMS ((void));
-static void compute_transp PARAMS ((rtx, int, sbitmap *, int));
-static void compute_transpout PARAMS ((void));
-static void compute_local_properties PARAMS ((sbitmap *, sbitmap *, sbitmap *,
- struct hash_table *));
-static void compute_cprop_data PARAMS ((void));
-static void find_used_regs PARAMS ((rtx *, void *));
-static int try_replace_reg PARAMS ((rtx, rtx, rtx));
-static struct expr *find_avail_set PARAMS ((int, rtx));
-static int cprop_jump PARAMS ((basic_block, rtx, rtx, rtx, rtx));
-static void mems_conflict_for_gcse_p PARAMS ((rtx, rtx, void *));
-static int load_killed_in_block_p PARAMS ((basic_block, int, rtx, int));
-static void canon_list_insert PARAMS ((rtx, rtx, void *));
-static int cprop_insn PARAMS ((rtx, int));
-static int cprop PARAMS ((int));
-static rtx fis_get_condition PARAMS ((rtx));
-static void find_implicit_sets PARAMS ((void));
-static int one_cprop_pass PARAMS ((int, int, int));
-static bool constprop_register PARAMS ((rtx, rtx, rtx, int));
-static struct expr *find_bypass_set PARAMS ((int, int));
-static int bypass_block PARAMS ((basic_block, rtx, rtx));
-static int bypass_conditional_jumps PARAMS ((void));
-static void alloc_pre_mem PARAMS ((int, int));
-static void free_pre_mem PARAMS ((void));
-static void compute_pre_data PARAMS ((void));
-static int pre_expr_reaches_here_p PARAMS ((basic_block, struct expr *,
- basic_block));
-static void insert_insn_end_bb PARAMS ((struct expr *, basic_block, int));
-static void pre_insert_copy_insn PARAMS ((struct expr *, rtx));
-static void pre_insert_copies PARAMS ((void));
-static int pre_delete PARAMS ((void));
-static int pre_gcse PARAMS ((void));
-static int one_pre_gcse_pass PARAMS ((int));
-static void add_label_notes PARAMS ((rtx, rtx));
-static void alloc_code_hoist_mem PARAMS ((int, int));
-static void free_code_hoist_mem PARAMS ((void));
-static void compute_code_hoist_vbeinout PARAMS ((void));
-static void compute_code_hoist_data PARAMS ((void));
-static int hoist_expr_reaches_here_p PARAMS ((basic_block, int, basic_block,
- char *));
-static void hoist_code PARAMS ((void));
-static int one_code_hoisting_pass PARAMS ((void));
-static void alloc_rd_mem PARAMS ((int, int));
-static void free_rd_mem PARAMS ((void));
-static void handle_rd_kill_set PARAMS ((rtx, int, basic_block));
-static void compute_kill_rd PARAMS ((void));
-static void compute_rd PARAMS ((void));
-static void alloc_avail_expr_mem PARAMS ((int, int));
-static void free_avail_expr_mem PARAMS ((void));
-static void compute_ae_gen PARAMS ((struct hash_table *));
-static int expr_killed_p PARAMS ((rtx, basic_block));
-static void compute_ae_kill PARAMS ((sbitmap *, sbitmap *, struct hash_table *));
-static int expr_reaches_here_p PARAMS ((struct occr *, struct expr *,
- basic_block, int));
-static rtx computing_insn PARAMS ((struct expr *, rtx));
-static int def_reaches_here_p PARAMS ((rtx, rtx));
-static int can_disregard_other_sets PARAMS ((struct reg_set **, rtx, int));
-static int handle_avail_expr PARAMS ((rtx, struct expr *));
-static int classic_gcse PARAMS ((void));
-static int one_classic_gcse_pass PARAMS ((int));
-static void invalidate_nonnull_info PARAMS ((rtx, rtx, void *));
-static int delete_null_pointer_checks_1 PARAMS ((unsigned int *,
- sbitmap *, sbitmap *,
- struct null_pointer_info *));
-static rtx process_insert_insn PARAMS ((struct expr *));
-static int pre_edge_insert PARAMS ((struct edge_list *, struct expr **));
-static int expr_reaches_here_p_work PARAMS ((struct occr *, struct expr *,
- basic_block, int, char *));
-static int pre_expr_reaches_here_p_work PARAMS ((basic_block, struct expr *,
- basic_block, char *));
-static struct ls_expr * ldst_entry PARAMS ((rtx));
-static void free_ldst_entry PARAMS ((struct ls_expr *));
-static void free_ldst_mems PARAMS ((void));
-static void print_ldst_list PARAMS ((FILE *));
-static struct ls_expr * find_rtx_in_ldst PARAMS ((rtx));
-static int enumerate_ldsts PARAMS ((void));
-static inline struct ls_expr * first_ls_expr PARAMS ((void));
-static inline struct ls_expr * next_ls_expr PARAMS ((struct ls_expr *));
-static int simple_mem PARAMS ((rtx));
-static void invalidate_any_buried_refs PARAMS ((rtx));
-static void compute_ld_motion_mems PARAMS ((void));
-static void trim_ld_motion_mems PARAMS ((void));
-static void update_ld_motion_stores PARAMS ((struct expr *));
-static void reg_set_info PARAMS ((rtx, rtx, void *));
-static int store_ops_ok PARAMS ((rtx, basic_block));
-static void find_moveable_store PARAMS ((rtx));
-static int compute_store_table PARAMS ((void));
-static int load_kills_store PARAMS ((rtx, rtx));
-static int find_loads PARAMS ((rtx, rtx));
-static int store_killed_in_insn PARAMS ((rtx, rtx));
-static int store_killed_after PARAMS ((rtx, rtx, basic_block));
-static int store_killed_before PARAMS ((rtx, rtx, basic_block));
-static void build_store_vectors PARAMS ((void));
-static void insert_insn_start_bb PARAMS ((rtx, basic_block));
-static int insert_store PARAMS ((struct ls_expr *, edge));
-static void replace_store_insn PARAMS ((rtx, rtx, basic_block));
-static void delete_store PARAMS ((struct ls_expr *,
- basic_block));
-static void free_store_memory PARAMS ((void));
-static void store_motion PARAMS ((void));
-static void free_insn_expr_list_list PARAMS ((rtx *));
-static void clear_modify_mem_tables PARAMS ((void));
-static void free_modify_mem_tables PARAMS ((void));
-static rtx gcse_emit_move_after PARAMS ((rtx, rtx, rtx));
-static void local_cprop_find_used_regs PARAMS ((rtx *, void *));
-static bool do_local_cprop PARAMS ((rtx, rtx, int, rtx*));
-static bool adjust_libcall_notes PARAMS ((rtx, rtx, rtx, rtx*));
-static void local_cprop_pass PARAMS ((int));
+static void compute_can_copy (void);
+static void *gmalloc (size_t) ATTRIBUTE_MALLOC;
+static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC;
+static void *grealloc (void *, size_t);
+static void *gcse_alloc (unsigned long);
+static void alloc_gcse_mem (rtx);
+static void free_gcse_mem (void);
+static void alloc_reg_set_mem (int);
+static void free_reg_set_mem (void);
+static void record_one_set (int, rtx);
+static void replace_one_set (int, rtx, rtx);
+static void record_set_info (rtx, rtx, void *);
+static void compute_sets (rtx);
+static void hash_scan_insn (rtx, struct hash_table *, int);
+static void hash_scan_set (rtx, rtx, struct hash_table *);
+static void hash_scan_clobber (rtx, rtx, struct hash_table *);
+static void hash_scan_call (rtx, rtx, struct hash_table *);
+static int want_to_gcse_p (rtx);
+static bool can_assign_to_reg_p (rtx);
+static bool gcse_constant_p (rtx);
+static int oprs_unchanged_p (rtx, rtx, int);
+static int oprs_anticipatable_p (rtx, rtx);
+static int oprs_available_p (rtx, rtx);
+static void insert_expr_in_table (rtx, enum machine_mode, rtx, int, int,
+ struct hash_table *);
+static void insert_set_in_table (rtx, rtx, struct hash_table *);
+static unsigned int hash_expr (rtx, enum machine_mode, int *, int);
+static unsigned int hash_expr_1 (rtx, enum machine_mode, int *);
+static unsigned int hash_string_1 (const char *);
+static unsigned int hash_set (int, int);
+static int expr_equiv_p (rtx, rtx);
+static void record_last_reg_set_info (rtx, int);
+static void record_last_mem_set_info (rtx);
+static void record_last_set_info (rtx, rtx, void *);
+static void compute_hash_table (struct hash_table *);
+static void alloc_hash_table (int, struct hash_table *, int);
+static void free_hash_table (struct hash_table *);
+static void compute_hash_table_work (struct hash_table *);
+static void dump_hash_table (FILE *, const char *, struct hash_table *);
+static struct expr *lookup_expr (rtx, struct hash_table *);
+static struct expr *lookup_set (unsigned int, struct hash_table *);
+static struct expr *next_set (unsigned int, struct expr *);
+static void reset_opr_set_tables (void);
+static int oprs_not_set_p (rtx, rtx);
+static void mark_call (rtx);
+static void mark_set (rtx, rtx);
+static void mark_clobber (rtx, rtx);
+static void mark_oprs_set (rtx);
+static void alloc_cprop_mem (int, int);
+static void free_cprop_mem (void);
+static void compute_transp (rtx, int, sbitmap *, int);
+static void compute_transpout (void);
+static void compute_local_properties (sbitmap *, sbitmap *, sbitmap *,
+ struct hash_table *);
+static void compute_cprop_data (void);
+static void find_used_regs (rtx *, void *);
+static int try_replace_reg (rtx, rtx, rtx);
+static struct expr *find_avail_set (int, rtx);
+static int cprop_jump (basic_block, rtx, rtx, rtx, rtx);
+static void mems_conflict_for_gcse_p (rtx, rtx, void *);
+static int load_killed_in_block_p (basic_block, int, rtx, int);
+static void canon_list_insert (rtx, rtx, void *);
+static int cprop_insn (rtx, int);
+static int cprop (int);
+static void find_implicit_sets (void);
+static int one_cprop_pass (int, int, int);
+static bool constprop_register (rtx, rtx, rtx, int);
+static struct expr *find_bypass_set (int, int);
+static bool reg_killed_on_edge (rtx, edge);
+static int bypass_block (basic_block, rtx, rtx);
+static int bypass_conditional_jumps (void);
+static void alloc_pre_mem (int, int);
+static void free_pre_mem (void);
+static void compute_pre_data (void);
+static int pre_expr_reaches_here_p (basic_block, struct expr *,
+ basic_block);
+static void insert_insn_end_bb (struct expr *, basic_block, int);
+static void pre_insert_copy_insn (struct expr *, rtx);
+static void pre_insert_copies (void);
+static int pre_delete (void);
+static int pre_gcse (void);
+static int one_pre_gcse_pass (int);
+static void add_label_notes (rtx, rtx);
+static void alloc_code_hoist_mem (int, int);
+static void free_code_hoist_mem (void);
+static void compute_code_hoist_vbeinout (void);
+static void compute_code_hoist_data (void);
+static int hoist_expr_reaches_here_p (basic_block, int, basic_block, char *);
+static void hoist_code (void);
+static int one_code_hoisting_pass (void);
+static rtx process_insert_insn (struct expr *);
+static int pre_edge_insert (struct edge_list *, struct expr **);
+static int pre_expr_reaches_here_p_work (basic_block, struct expr *,
+ basic_block, char *);
+static struct ls_expr * ldst_entry (rtx);
+static void free_ldst_entry (struct ls_expr *);
+static void free_ldst_mems (void);
+static void print_ldst_list (FILE *);
+static struct ls_expr * find_rtx_in_ldst (rtx);
+static int enumerate_ldsts (void);
+static inline struct ls_expr * first_ls_expr (void);
+static inline struct ls_expr * next_ls_expr (struct ls_expr *);
+static int simple_mem (rtx);
+static void invalidate_any_buried_refs (rtx);
+static void compute_ld_motion_mems (void);
+static void trim_ld_motion_mems (void);
+static void update_ld_motion_stores (struct expr *);
+static void reg_set_info (rtx, rtx, void *);
+static void reg_clear_last_set (rtx, rtx, void *);
+static bool store_ops_ok (rtx, int *);
+static rtx extract_mentioned_regs (rtx);
+static rtx extract_mentioned_regs_helper (rtx, rtx);
+static void find_moveable_store (rtx, int *, int *);
+static int compute_store_table (void);
+static bool load_kills_store (rtx, rtx, int);
+static bool find_loads (rtx, rtx, int);
+static bool store_killed_in_insn (rtx, rtx, rtx, int);
+static bool store_killed_after (rtx, rtx, rtx, basic_block, int *, rtx *);
+static bool store_killed_before (rtx, rtx, rtx, basic_block, int *);
+static void build_store_vectors (void);
+static void insert_insn_start_bb (rtx, basic_block);
+static int insert_store (struct ls_expr *, edge);
+static void remove_reachable_equiv_notes (basic_block, struct ls_expr *);
+static void replace_store_insn (rtx, rtx, basic_block, struct ls_expr *);
+static void delete_store (struct ls_expr *, basic_block);
+static void free_store_memory (void);
+static void store_motion (void);
+static void free_insn_expr_list_list (rtx *);
+static void clear_modify_mem_tables (void);
+static void free_modify_mem_tables (void);
+static rtx gcse_emit_move_after (rtx, rtx, rtx);
+static void local_cprop_find_used_regs (rtx *, void *);
+static bool do_local_cprop (rtx, rtx, int, rtx*);
+static bool adjust_libcall_notes (rtx, rtx, rtx, rtx*);
+static void local_cprop_pass (int);
+static bool is_too_expensive (const char *);
\f
+
/* Entry point for global common subexpression elimination.
F is the first instruction in the function. */
int
-gcse_main (f, file)
- rtx f;
- FILE *file;
+gcse_main (rtx f, FILE *file)
{
int changed, pass;
/* Bytes used at start of pass. */
if (file)
dump_flow_info (file);
- /* Return if there's nothing to do. */
- if (n_basic_blocks <= 1)
+ /* Return if there's nothing to do, or it is too expensive. */
+ if (n_basic_blocks <= 1 || is_too_expensive (_("GCSE disabled")))
return 0;
- /* Trying to perform global optimizations on flow graphs which have
- a high connectivity will take a long time and is unlikely to be
- particularly useful.
-
- In normal circumstances a cfg should have about twice as many edges
- as blocks. But we do not want to punish small functions which have
- a couple switch statements. So we require a relatively large number
- of basic blocks and the ratio of edges to blocks to be high. */
- if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
- {
- if (warn_disabled_optimization)
- warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
- n_basic_blocks, n_edges / n_basic_blocks);
- return 0;
- }
-
- /* If allocating memory for the cprop bitmap would take up too much
- storage it's better just to disable the optimization. */
- if ((n_basic_blocks
- * SBITMAP_SET_SIZE (max_gcse_regno)
- * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
- {
- if (warn_disabled_optimization)
- warning ("GCSE disabled: %d basic blocks and %d registers",
- n_basic_blocks, max_gcse_regno);
-
- return 0;
- }
-
- /* See what modes support reg/reg copy operations. */
- if (! can_copy_init_p)
- {
- compute_can_copy ();
- can_copy_init_p = 1;
- }
-
gcc_obstack_init (&gcse_obstack);
bytes_used = 0;
changed = one_cprop_pass (pass + 1, 0, 0);
if (optimize_size)
- changed |= one_classic_gcse_pass (pass + 1);
+ /* Do nothing. */ ;
else
{
changed |= one_pre_gcse_pass (pass + 1);
if (changed)
{
free_modify_mem_tables ();
- modify_mem_list
- = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
- canon_modify_mem_list
- = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
- memset ((char *) modify_mem_list, 0, last_basic_block * sizeof (rtx));
- memset ((char *) canon_modify_mem_list, 0, last_basic_block * sizeof (rtx));
+ modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
+ canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
}
free_reg_set_mem ();
alloc_reg_set_mem (max_reg_num ());
partial redundancy elimination. */
free_gcse_mem ();
- /* It does not make sense to run code hoisting unless we optimizing
+ /* It does not make sense to run code hoisting unless we are optimizing
for code size -- it rarely makes programs faster, and can make
them bigger if we did partial redundancy elimination (when optimizing
- for space, we use a classic gcse algorithm instead of partial
- redundancy algorithms). */
+ for space, we don't run the partial redundancy algorithms). */
if (optimize_size)
{
max_gcse_regno = max_reg_num ();
if (file)
{
fprintf (file, "GCSE of %s: %d basic blocks, ",
- current_function_name, n_basic_blocks);
+ current_function_name (), n_basic_blocks);
fprintf (file, "%d pass%s, %d bytes\n\n",
pass, pass > 1 ? "es" : "", max_pass_bytes);
}
obstack_free (&gcse_obstack, NULL);
free_reg_set_mem ();
+
/* We are finished with alias. */
end_alias_analysis ();
allocate_reg_info (max_reg_num (), FALSE, FALSE);
- /* Store motion disabled until it is fixed. */
- if (0 && !optimize_size && flag_gcse_sm)
+ if (!optimize_size && flag_gcse_sm)
store_motion ();
+
/* Record where pseudo-registers are set. */
return run_jump_opt_after_gcse;
}
\f
/* Misc. utilities. */
+/* Nonzero for each mode that supports (set (reg) (reg)).
+ This is trivially true for integer and floating point values.
+ It may or may not be true for condition codes. */
+static char can_copy[(int) NUM_MACHINE_MODES];
+
/* Compute which modes support reg/reg copy operations. */
static void
-compute_can_copy ()
+compute_can_copy (void)
{
int i;
#ifndef AVOID_CCMODE_COPIES
rtx reg, insn;
#endif
- memset (can_copy_p, 0, NUM_MACHINE_MODES);
+ memset (can_copy, 0, NUM_MACHINE_MODES);
start_sequence ();
for (i = 0; i < NUM_MACHINE_MODES; i++)
if (GET_MODE_CLASS (i) == MODE_CC)
{
#ifdef AVOID_CCMODE_COPIES
- can_copy_p[i] = 0;
+ can_copy[i] = 0;
#else
reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
if (recog (PATTERN (insn), insn, NULL) >= 0)
- can_copy_p[i] = 1;
+ can_copy[i] = 1;
#endif
}
else
- can_copy_p[i] = 1;
+ can_copy[i] = 1;
end_sequence ();
}
+
+/* Returns whether the mode supports reg/reg copy operations. */
+
+bool
+can_copy_p (enum machine_mode mode)
+{
+ static bool can_copy_init_p = false;
+
+ if (! can_copy_init_p)
+ {
+ compute_can_copy ();
+ can_copy_init_p = true;
+ }
+
+ return can_copy[mode] != 0;
+}
\f
/* Cover function to xmalloc to record bytes allocated. */
-static char *
-gmalloc (size)
- unsigned int size;
+static void *
+gmalloc (size_t size)
{
bytes_used += size;
return xmalloc (size);
}
+/* Cover function to xcalloc to record bytes allocated. */
+
+static void *
+gcalloc (size_t nelem, size_t elsize)
+{
+ bytes_used += nelem * elsize;
+ return xcalloc (nelem, elsize);
+}
+
/* Cover function to xrealloc.
We don't record the additional size since we don't know it.
It won't affect memory usage stats much anyway. */
-static char *
-grealloc (ptr, size)
- char *ptr;
- unsigned int size;
+static void *
+grealloc (void *ptr, size_t size)
{
return xrealloc (ptr, size);
}
/* Cover function to obstack_alloc. */
-static char *
-gcse_alloc (size)
- unsigned long size;
+static void *
+gcse_alloc (unsigned long size)
{
bytes_used += size;
- return (char *) obstack_alloc (&gcse_obstack, size);
+ return obstack_alloc (&gcse_obstack, size);
}
/* Allocate memory for the cuid mapping array,
This is called at the start of each pass. */
static void
-alloc_gcse_mem (f)
- rtx f;
+alloc_gcse_mem (rtx f)
{
- int i, n;
+ int i;
rtx insn;
/* Find the largest UID and create a mapping from UIDs to CUIDs.
and only apply to real insns. */
max_uid = get_max_uid ();
- n = (max_uid + 1) * sizeof (int);
- uid_cuid = (int *) gmalloc (n);
- memset ((char *) uid_cuid, 0, n);
+ uid_cuid = gcalloc (max_uid + 1, sizeof (int));
for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
{
if (INSN_P (insn))
/* Create a table mapping cuids to insns. */
max_cuid = i;
- n = (max_cuid + 1) * sizeof (rtx);
- cuid_insn = (rtx *) gmalloc (n);
- memset ((char *) cuid_insn, 0, n);
+ cuid_insn = gcalloc (max_cuid + 1, sizeof (rtx));
for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
if (INSN_P (insn))
CUID_INSN (i++) = insn;
reg_set_bitmap = BITMAP_XMALLOC ();
/* Allocate vars to track sets of regs, memory per block. */
- reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (last_basic_block,
- max_gcse_regno);
+ reg_set_in_block = sbitmap_vector_alloc (last_basic_block, max_gcse_regno);
/* Allocate array to keep a list of insns which modify memory in each
basic block. */
- modify_mem_list = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
- canon_modify_mem_list = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
- memset ((char *) modify_mem_list, 0, last_basic_block * sizeof (rtx));
- memset ((char *) canon_modify_mem_list, 0, last_basic_block * sizeof (rtx));
+ modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
+ canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
modify_mem_list_set = BITMAP_XMALLOC ();
canon_modify_mem_list_set = BITMAP_XMALLOC ();
}
/* Free memory allocated by alloc_gcse_mem. */
static void
-free_gcse_mem ()
+free_gcse_mem (void)
{
free (uid_cuid);
free (cuid_insn);
BITMAP_XFREE (modify_mem_list_set);
BITMAP_XFREE (canon_modify_mem_list_set);
}
-
-/* Many of the global optimization algorithms work by solving dataflow
- equations for various expressions. Initially, some local value is
- computed for each expression in each block. Then, the values across the
- various blocks are combined (by following flow graph edges) to arrive at
- global values. Conceptually, each set of equations is independent. We
- may therefore solve all the equations in parallel, solve them one at a
- time, or pick any intermediate approach.
-
- When you're going to need N two-dimensional bitmaps, each X (say, the
- number of blocks) by Y (say, the number of expressions), call this
- function. It's not important what X and Y represent; only that Y
- correspond to the things that can be done in parallel. This function will
- return an appropriate chunking factor C; you should solve C sets of
- equations in parallel. By going through this function, we can easily
- trade space against time; by solving fewer equations in parallel we use
- less space. */
-
-static int
-get_bitmap_width (n, x, y)
- int n;
- int x;
- int y;
-{
- /* It's not really worth figuring out *exactly* how much memory will
- be used by a particular choice. The important thing is to get
- something approximately right. */
- size_t max_bitmap_memory = 10 * 1024 * 1024;
-
- /* The number of bytes we'd use for a single column of minimum
- width. */
- size_t column_size = n * x * sizeof (SBITMAP_ELT_TYPE);
-
- /* Often, it's reasonable just to solve all the equations in
- parallel. */
- if (column_size * SBITMAP_SET_SIZE (y) <= max_bitmap_memory)
- return y;
-
- /* Otherwise, pick the largest width we can, without going over the
- limit. */
- return SBITMAP_ELT_BITS * ((max_bitmap_memory + column_size - 1)
- / column_size);
-}
\f
/* Compute the local properties of each recorded expression.
ABSALTERED. */
static void
-compute_local_properties (transp, comp, antloc, table)
- sbitmap *transp;
- sbitmap *comp;
- sbitmap *antloc;
- struct hash_table *table;
+compute_local_properties (sbitmap *transp, sbitmap *comp, sbitmap *antloc,
+ struct hash_table *table)
{
unsigned int i;
static struct obstack reg_set_obstack;
static void
-alloc_reg_set_mem (n_regs)
- int n_regs;
+alloc_reg_set_mem (int n_regs)
{
- unsigned int n;
-
reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
- n = reg_set_table_size * sizeof (struct reg_set *);
- reg_set_table = (struct reg_set **) gmalloc (n);
- memset ((char *) reg_set_table, 0, n);
+ reg_set_table = gcalloc (reg_set_table_size, sizeof (struct reg_set *));
gcc_obstack_init (®_set_obstack);
}
static void
-free_reg_set_mem ()
+free_reg_set_mem (void)
{
free (reg_set_table);
obstack_free (®_set_obstack, NULL);
}
+/* An OLD_INSN that used to set REGNO was replaced by NEW_INSN.
+ Update the corresponding `reg_set_table' entry accordingly.
+ We assume that NEW_INSN is not already recorded in reg_set_table[regno]. */
+
+static void
+replace_one_set (int regno, rtx old_insn, rtx new_insn)
+{
+ struct reg_set *reg_info;
+ if (regno >= reg_set_table_size)
+ return;
+ for (reg_info = reg_set_table[regno]; reg_info; reg_info = reg_info->next)
+ if (reg_info->insn == old_insn)
+ {
+ reg_info->insn = new_insn;
+ break;
+ }
+}
+
/* Record REGNO in the reg_set table. */
static void
-record_one_set (regno, insn)
- int regno;
- rtx insn;
+record_one_set (int regno, rtx insn)
{
/* Allocate a new reg_set element and link it onto the list. */
struct reg_set *new_reg_info;
{
int new_size = regno + REG_SET_TABLE_SLOP;
- reg_set_table
- = (struct reg_set **) grealloc ((char *) reg_set_table,
- new_size * sizeof (struct reg_set *));
- memset ((char *) (reg_set_table + reg_set_table_size), 0,
+ reg_set_table = grealloc (reg_set_table,
+ new_size * sizeof (struct reg_set *));
+ memset (reg_set_table + reg_set_table_size, 0,
(new_size - reg_set_table_size) * sizeof (struct reg_set *));
reg_set_table_size = new_size;
}
- new_reg_info = (struct reg_set *) obstack_alloc (®_set_obstack,
- sizeof (struct reg_set));
+ new_reg_info = obstack_alloc (®_set_obstack, sizeof (struct reg_set));
bytes_used += sizeof (struct reg_set);
new_reg_info->insn = insn;
new_reg_info->next = reg_set_table[regno];
occurring. */
static void
-record_set_info (dest, setter, data)
- rtx dest, setter ATTRIBUTE_UNUSED;
- void *data;
+record_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
{
rtx record_set_insn = (rtx) data;
- if (GET_CODE (dest) == REG && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
+ if (REG_P (dest) && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
record_one_set (REGNO (dest), record_set_insn);
}
`reg_set_table' for further documentation. */
static void
-compute_sets (f)
- rtx f;
+compute_sets (rtx f)
{
rtx insn;
/* See whether X, the source of a set, is something we want to consider for
GCSE. */
-static GTY(()) rtx test_insn;
static int
-want_to_gcse_p (x)
- rtx x;
+want_to_gcse_p (rtx x)
{
- int num_clobbers = 0;
- int icode;
-
switch (GET_CODE (x))
{
case REG:
case CONST_DOUBLE:
case CONST_VECTOR:
case CALL:
- case CONSTANT_P_RTX:
return 0;
default:
- break;
+ return can_assign_to_reg_p (x);
}
+}
+
+/* Used internally by can_assign_to_reg_p. */
+
+static GTY(()) rtx test_insn;
+
+/* Return true if we can assign X to a pseudo register. */
+
+static bool
+can_assign_to_reg_p (rtx x)
+{
+ int num_clobbers = 0;
+ int icode;
/* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
if (general_operand (x, GET_MODE (x)))
or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
static int
-oprs_unchanged_p (x, insn, avail_p)
- rtx x, insn;
- int avail_p;
+oprs_unchanged_p (rtx x, rtx insn, int avail_p)
{
int i, j;
enum rtx_code code;
gcse_mems_conflict_p to a nonzero value. */
static void
-mems_conflict_for_gcse_p (dest, setter, data)
- rtx dest, setter ATTRIBUTE_UNUSED;
- void *data ATTRIBUTE_UNUSED;
+mems_conflict_for_gcse_p (rtx dest, rtx setter ATTRIBUTE_UNUSED,
+ void *data ATTRIBUTE_UNUSED)
{
while (GET_CODE (dest) == SUBREG
|| GET_CODE (dest) == ZERO_EXTRACT
/* If DEST is not a MEM, then it will not conflict with the load. Note
that function calls are assumed to clobber memory, but are handled
elsewhere. */
- if (GET_CODE (dest) != MEM)
+ if (! MEM_P (dest))
return;
/* If we are setting a MEM in our list of specially recognized MEMs,
don't mark as killed this time. */
- if (dest == gcse_mem_operand && pre_ldst_mems != NULL)
+ if (expr_equiv_p (dest, gcse_mem_operand) && pre_ldst_mems != NULL)
{
if (!find_rtx_in_ldst (dest))
gcse_mems_conflict_p = 1;
AVAIL_P to 0. */
static int
-load_killed_in_block_p (bb, uid_limit, x, avail_p)
- basic_block bb;
- int uid_limit;
- rtx x;
- int avail_p;
+load_killed_in_block_p (basic_block bb, int uid_limit, rtx x, int avail_p)
{
rtx list_entry = modify_mem_list[bb->index];
while (list_entry)
/* If SETTER is a call everything is clobbered. Note that calls
to pure functions are never put on the list, so we need not
worry about them. */
- if (GET_CODE (setter) == CALL_INSN)
+ if (CALL_P (setter))
return 1;
/* SETTER must be an INSN of some kind that sets memory. Call
the start of INSN's basic block up to but not including INSN. */
static int
-oprs_anticipatable_p (x, insn)
- rtx x, insn;
+oprs_anticipatable_p (rtx x, rtx insn)
{
return oprs_unchanged_p (x, insn, 0);
}
INSN to the end of INSN's basic block. */
static int
-oprs_available_p (x, insn)
- rtx x, insn;
+oprs_available_p (rtx x, rtx insn)
{
return oprs_unchanged_p (x, insn, 1);
}
MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
indicating if a volatile operand is found or if the expression contains
- something we don't want to insert in the table.
+ something we don't want to insert in the table. HASH_TABLE_SIZE is
+ the current size of the hash table to be probed.
??? One might want to merge this with canon_hash. Later. */
static unsigned int
-hash_expr (x, mode, do_not_record_p, hash_table_size)
- rtx x;
- enum machine_mode mode;
- int *do_not_record_p;
- int hash_table_size;
+hash_expr (rtx x, enum machine_mode mode, int *do_not_record_p,
+ int hash_table_size)
{
unsigned int hash;
/* Hash a string. Just add its bytes up. */
static inline unsigned
-hash_string_1 (ps)
- const char *ps;
+hash_string_1 (const char *ps)
{
unsigned hash = 0;
const unsigned char *p = (const unsigned char *) ps;
/* Subroutine of hash_expr to do the actual work. */
static unsigned int
-hash_expr_1 (x, mode, do_not_record_p)
- rtx x;
- enum machine_mode mode;
- int *do_not_record_p;
+hash_expr_1 (rtx x, enum machine_mode mode, int *do_not_record_p)
{
int i, j;
unsigned hash = 0;
enum rtx_code code;
const char *fmt;
- /* Used to turn recursion into iteration. We can't rely on GCC's
- tail-recursion elimination since we need to keep accumulating values
- in HASH. */
-
if (x == 0)
return hash;
+ /* Used to turn recursion into iteration. We can't rely on GCC's
+ tail-recursion elimination since we need to keep accumulating values
+ in HASH. */
repeat:
+
code = GET_CODE (x);
switch (code)
{
??? May need to make things more elaborate. Later, as necessary. */
static unsigned int
-hash_set (regno, hash_table_size)
- int regno;
- int hash_table_size;
+hash_set (int regno, int hash_table_size)
{
unsigned int hash;
??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
static int
-expr_equiv_p (x, y)
- rtx x, y;
+expr_equiv_p (rtx x, rtx y)
{
int i, j;
enum rtx_code code;
return 1;
if (x == 0 || y == 0)
- return x == y;
+ return 0;
code = GET_CODE (x);
if (code != GET_CODE (y))
{
case PC:
case CC0:
- return x == y;
-
case CONST_INT:
- return INTVAL (x) == INTVAL (y);
+ return 0;
case LABEL_REF:
return XEXP (x, 0) == XEXP (y, 0);
due to it being set with the different alias set. */
if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
return 0;
+
+ /* A volatile mem should not be considered equivalent to any other. */
+ if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
+ return 0;
break;
/* For commutative operations, check both orders. */
AVAIL_P is nonzero if X is an available expression. */
static void
-insert_expr_in_table (x, mode, insn, antic_p, avail_p, table)
- rtx x;
- enum machine_mode mode;
- rtx insn;
- int antic_p, avail_p;
- struct hash_table *table;
+insert_expr_in_table (rtx x, enum machine_mode mode, rtx insn, int antic_p,
+ int avail_p, struct hash_table *table)
{
int found, do_not_record_p;
unsigned int hash;
if (! found)
{
- cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr));
+ cur_expr = gcse_alloc (sizeof (struct expr));
bytes_used += sizeof (struct expr);
if (table->table[hash] == NULL)
/* This is the first pattern that hashed to this index. */
else
{
/* First occurrence of this expression in this basic block. */
- antic_occr = (struct occr *) gcse_alloc (sizeof (struct occr));
+ antic_occr = gcse_alloc (sizeof (struct occr));
bytes_used += sizeof (struct occr);
/* First occurrence of this expression in any block? */
if (cur_expr->antic_occr == NULL)
antic_occr->insn = insn;
antic_occr->next = NULL;
+ antic_occr->deleted_p = 0;
}
}
else
{
/* First occurrence of this expression in this basic block. */
- avail_occr = (struct occr *) gcse_alloc (sizeof (struct occr));
+ avail_occr = gcse_alloc (sizeof (struct occr));
bytes_used += sizeof (struct occr);
/* First occurrence of this expression in any block? */
avail_occr->insn = insn;
avail_occr->next = NULL;
+ avail_occr->deleted_p = 0;
}
}
}
basic block. */
static void
-insert_set_in_table (x, insn, table)
- rtx x;
- rtx insn;
- struct hash_table *table;
+insert_set_in_table (rtx x, rtx insn, struct hash_table *table)
{
int found;
unsigned int hash;
struct occr *cur_occr, *last_occr = NULL;
if (GET_CODE (x) != SET
- || GET_CODE (SET_DEST (x)) != REG)
+ || ! REG_P (SET_DEST (x)))
abort ();
hash = hash_set (REGNO (SET_DEST (x)), table->size);
if (! found)
{
- cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr));
+ cur_expr = gcse_alloc (sizeof (struct expr));
bytes_used += sizeof (struct expr);
if (table->table[hash] == NULL)
/* This is the first pattern that hashed to this index. */
else
{
/* First occurrence of this expression in this basic block. */
- cur_occr = (struct occr *) gcse_alloc (sizeof (struct occr));
+ cur_occr = gcse_alloc (sizeof (struct occr));
bytes_used += sizeof (struct occr);
/* First occurrence of this expression in any block? */
cur_occr->insn = insn;
cur_occr->next = NULL;
+ cur_occr->deleted_p = 0;
}
}
+/* Determine whether the rtx X should be treated as a constant for
+ the purposes of GCSE's constant propagation. */
+
+static bool
+gcse_constant_p (rtx x)
+{
+ /* Consider a COMPARE of two integers constant. */
+ if (GET_CODE (x) == COMPARE
+ && GET_CODE (XEXP (x, 0)) == CONST_INT
+ && GET_CODE (XEXP (x, 1)) == CONST_INT)
+ return true;
+
+ /* Consider a COMPARE of the same registers is a constant
+ if they are not floating point registers. */
+ if (GET_CODE(x) == COMPARE
+ && REG_P (XEXP (x, 0)) && REG_P (XEXP (x, 1))
+ && REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 1))
+ && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 0)))
+ && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 1))))
+ return true;
+
+ return CONSTANT_P (x);
+}
+
/* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
expression one). */
static void
-hash_scan_set (pat, insn, table)
- rtx pat, insn;
- struct hash_table *table;
+hash_scan_set (rtx pat, rtx insn, struct hash_table *table)
{
rtx src = SET_SRC (pat);
rtx dest = SET_DEST (pat);
if (GET_CODE (src) == CALL)
hash_scan_call (src, insn, table);
- else if (GET_CODE (dest) == REG)
+ else if (REG_P (dest))
{
unsigned int regno = REGNO (dest);
rtx tmp;
/* If this is a single set and we are doing constant propagation,
see if a REG_NOTE shows this equivalent to a constant. */
if (table->set_p && (note = find_reg_equal_equiv_note (insn)) != 0
- && CONSTANT_P (XEXP (note, 0)))
+ && gcse_constant_p (XEXP (note, 0)))
src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
/* Only record sets of pseudo-regs in the hash table. */
if (! table->set_p
&& regno >= FIRST_PSEUDO_REGISTER
/* Don't GCSE something if we can't do a reg/reg copy. */
- && can_copy_p [GET_MODE (dest)]
+ && can_copy_p (GET_MODE (dest))
/* GCSE commonly inserts instruction after the insn. We can't
do that easily for EH_REGION notes so disable GCSE on these
for now. */
explicitly, it means address of parameter has been taken,
so we should not extend the lifetime of the pseudo. */
&& ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
- || GET_CODE (XEXP (note, 0)) != MEM))
+ || ! MEM_P (XEXP (note, 0))))
{
/* An expression is not anticipatable if its operands are
modified before this insn or if this is not the only SET in
/* Record sets for constant/copy propagation. */
else if (table->set_p
&& regno >= FIRST_PSEUDO_REGISTER
- && ((GET_CODE (src) == REG
+ && ((REG_P (src)
&& REGNO (src) >= FIRST_PSEUDO_REGISTER
- && can_copy_p [GET_MODE (dest)]
+ && can_copy_p (GET_MODE (dest))
&& REGNO (src) != regno)
- || (CONSTANT_P (src)
- && GET_CODE (src) != CONSTANT_P_RTX))
+ || gcse_constant_p (src))
/* A copy is not available if its src or dest is subsequently
modified. Here we want to search from INSN+1 on, but
oprs_available_p searches from INSN on. */
- && (insn == BLOCK_END (BLOCK_NUM (insn))
+ && (insn == BB_END (BLOCK_FOR_INSN (insn))
|| ((tmp = next_nonnote_insn (insn)) != NULL_RTX
&& oprs_available_p (pat, tmp))))
insert_set_in_table (pat, insn, table);
}
+ /* In case of store we want to consider the memory value as available in
+ the REG stored in that memory. This makes it possible to remove
+ redundant loads from due to stores to the same location. */
+ else if (flag_gcse_las && REG_P (src) && MEM_P (dest))
+ {
+ unsigned int regno = REGNO (src);
+
+ /* Do not do this for constant/copy propagation. */
+ if (! table->set_p
+ /* Only record sets of pseudo-regs in the hash table. */
+ && regno >= FIRST_PSEUDO_REGISTER
+ /* Don't GCSE something if we can't do a reg/reg copy. */
+ && can_copy_p (GET_MODE (src))
+ /* GCSE commonly inserts instruction after the insn. We can't
+ do that easily for EH_REGION notes so disable GCSE on these
+ for now. */
+ && ! find_reg_note (insn, REG_EH_REGION, NULL_RTX)
+ /* Is SET_DEST something we want to gcse? */
+ && want_to_gcse_p (dest)
+ /* Don't CSE a nop. */
+ && ! set_noop_p (pat)
+ /* Don't GCSE if it has attached REG_EQUIV note.
+ At this point this only function parameters should have
+ REG_EQUIV notes and if the argument slot is used somewhere
+ explicitly, it means address of parameter has been taken,
+ so we should not extend the lifetime of the pseudo. */
+ && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
+ || ! MEM_P (XEXP (note, 0))))
+ {
+ /* Stores are never anticipatable. */
+ int antic_p = 0;
+ /* An expression is not available if its operands are
+ subsequently modified, including this insn. It's also not
+ available if this is a branch, because we can't insert
+ a set after the branch. */
+ int avail_p = oprs_available_p (dest, insn)
+ && ! JUMP_P (insn);
+
+ /* Record the memory expression (DEST) in the hash table. */
+ insert_expr_in_table (dest, GET_MODE (dest), insn,
+ antic_p, avail_p, table);
+ }
+ }
}
static void
-hash_scan_clobber (x, insn, table)
- rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED;
- struct hash_table *table ATTRIBUTE_UNUSED;
+hash_scan_clobber (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
+ struct hash_table *table ATTRIBUTE_UNUSED)
{
/* Currently nothing to do. */
}
static void
-hash_scan_call (x, insn, table)
- rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED;
- struct hash_table *table ATTRIBUTE_UNUSED;
+hash_scan_call (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
+ struct hash_table *table ATTRIBUTE_UNUSED)
{
/* Currently nothing to do. */
}
not record any expressions. */
static void
-hash_scan_insn (insn, table, in_libcall_block)
- rtx insn;
- struct hash_table *table;
- int in_libcall_block;
+hash_scan_insn (rtx insn, struct hash_table *table, int in_libcall_block)
{
rtx pat = PATTERN (insn);
int i;
}
static void
-dump_hash_table (file, name, table)
- FILE *file;
- const char *name;
- struct hash_table *table;
+dump_hash_table (FILE *file, const char *name, struct hash_table *table)
{
int i;
/* Flattened out table, so it's printed in proper order. */
unsigned int *hash_val;
struct expr *expr;
- flat_table
- = (struct expr **) xcalloc (table->n_elems, sizeof (struct expr *));
- hash_val = (unsigned int *) xmalloc (table->n_elems * sizeof (unsigned int));
+ flat_table = xcalloc (table->n_elems, sizeof (struct expr *));
+ hash_val = xmalloc (table->n_elems * sizeof (unsigned int));
for (i = 0; i < (int) table->size; i++)
for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
and is used to compute "transparency". */
static void
-record_last_reg_set_info (insn, regno)
- rtx insn;
- int regno;
+record_last_reg_set_info (rtx insn, int regno)
{
struct reg_avail_info *info = ®_avail_info[regno];
int cuid = INSN_CUID (insn);
taken off pairwise. */
static void
-canon_list_insert (dest, unused1, v_insn)
- rtx dest ATTRIBUTE_UNUSED;
- rtx unused1 ATTRIBUTE_UNUSED;
- void * v_insn;
+canon_list_insert (rtx dest ATTRIBUTE_UNUSED, rtx unused1 ATTRIBUTE_UNUSED,
+ void * v_insn)
{
rtx dest_addr, insn;
int bb;
that function calls are assumed to clobber memory, but are handled
elsewhere. */
- if (GET_CODE (dest) != MEM)
+ if (! MEM_P (dest))
return;
dest_addr = get_addr (XEXP (dest, 0));
a CALL_INSN). We merely need to record which insns modify memory. */
static void
-record_last_mem_set_info (insn)
- rtx insn;
+record_last_mem_set_info (rtx insn)
{
int bb = BLOCK_NUM (insn);
modify_mem_list[bb] = alloc_INSN_LIST (insn, modify_mem_list[bb]);
bitmap_set_bit (modify_mem_list_set, bb);
- if (GET_CODE (insn) == CALL_INSN)
+ if (CALL_P (insn))
{
/* Note that traversals of this loop (other than for free-ing)
will break after encountering a CALL_INSN. So, there's no
the SET is taking place. */
static void
-record_last_set_info (dest, setter, data)
- rtx dest, setter ATTRIBUTE_UNUSED;
- void *data;
+record_last_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
{
rtx last_set_insn = (rtx) data;
if (GET_CODE (dest) == SUBREG)
dest = SUBREG_REG (dest);
- if (GET_CODE (dest) == REG)
+ if (REG_P (dest))
record_last_reg_set_info (last_set_insn, REGNO (dest));
- else if (GET_CODE (dest) == MEM
+ else if (MEM_P (dest)
/* Ignore pushes, they clobber nothing. */
&& ! push_operand (dest, GET_MODE (dest)))
record_last_mem_set_info (last_set_insn);
TABLE is the table computed. */
static void
-compute_hash_table_work (table)
- struct hash_table *table;
+compute_hash_table_work (struct hash_table *table)
{
unsigned int i;
/* re-Cache any INSN_LIST nodes we have allocated. */
clear_modify_mem_tables ();
/* Some working arrays used to track first and last set in each block. */
- reg_avail_info = (struct reg_avail_info*)
- gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
+ reg_avail_info = gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
for (i = 0; i < max_gcse_regno; ++i)
reg_avail_info[i].last_bb = NULL;
??? hard-reg reg_set_in_block computation
could be moved to compute_sets since they currently don't change. */
- for (insn = current_bb->head;
- insn && insn != NEXT_INSN (current_bb->end);
+ for (insn = BB_HEAD (current_bb);
+ insn && insn != NEXT_INSN (BB_END (current_bb));
insn = NEXT_INSN (insn))
{
if (! INSN_P (insn))
continue;
- if (GET_CODE (insn) == CALL_INSN)
+ if (CALL_P (insn))
{
bool clobbers_all = false;
#ifdef NON_SAVING_SETJMP
if (table->set_p
&& implicit_sets[current_bb->index] != NULL_RTX)
hash_scan_set (implicit_sets[current_bb->index],
- current_bb->head, table);
+ BB_HEAD (current_bb), table);
/* The next pass builds the hash table. */
- for (insn = current_bb->head, in_libcall_block = 0;
- insn && insn != NEXT_INSN (current_bb->end);
+ for (insn = BB_HEAD (current_bb), in_libcall_block = 0;
+ insn && insn != NEXT_INSN (BB_END (current_bb));
insn = NEXT_INSN (insn))
if (INSN_P (insn))
{
be created. */
static void
-alloc_hash_table (n_insns, table, set_p)
- int n_insns;
- struct hash_table *table;
- int set_p;
+alloc_hash_table (int n_insns, struct hash_table *table, int set_p)
{
int n;
??? Later take some measurements. */
table->size |= 1;
n = table->size * sizeof (struct expr *);
- table->table = (struct expr **) gmalloc (n);
+ table->table = gmalloc (n);
table->set_p = set_p;
}
/* Free things allocated by alloc_hash_table. */
static void
-free_hash_table (table)
- struct hash_table *table;
+free_hash_table (struct hash_table *table)
{
free (table->table);
}
expression hash table. */
static void
-compute_hash_table (table)
- struct hash_table *table;
+compute_hash_table (struct hash_table *table)
{
/* Initialize count of number of entries in hash table. */
table->n_elems = 0;
- memset ((char *) table->table, 0,
- table->size * sizeof (struct expr *));
+ memset (table->table, 0, table->size * sizeof (struct expr *));
compute_hash_table_work (table);
}
The result is a pointer to the table entry, or NULL if not found. */
static struct expr *
-lookup_expr (pat, table)
- rtx pat;
- struct hash_table *table;
+lookup_expr (rtx pat, struct hash_table *table)
{
int do_not_record_p;
unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p,
table entry, or NULL if not found. */
static struct expr *
-lookup_set (regno, table)
- unsigned int regno;
- struct hash_table *table;
+lookup_set (unsigned int regno, struct hash_table *table)
{
unsigned int hash = hash_set (regno, table->size);
struct expr *expr;
/* Return the next entry for REGNO in list EXPR. */
static struct expr *
-next_set (regno, expr)
- unsigned int regno;
- struct expr *expr;
+next_set (unsigned int regno, struct expr *expr)
{
do
expr = expr->next_same_hash;
types may be mixed. */
static void
-free_insn_expr_list_list (listp)
- rtx *listp;
+free_insn_expr_list_list (rtx *listp)
{
rtx list, next;
/* Clear canon_modify_mem_list and modify_mem_list tables. */
static void
-clear_modify_mem_tables ()
+clear_modify_mem_tables (void)
{
int i;
/* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
static void
-free_modify_mem_tables ()
+free_modify_mem_tables (void)
{
clear_modify_mem_tables ();
free (modify_mem_list);
start of the block]. */
static void
-reset_opr_set_tables ()
+reset_opr_set_tables (void)
{
/* Maintain a bitmap of which regs have been set since beginning of
the block. */
INSN's basic block. */
static int
-oprs_not_set_p (x, insn)
- rtx x, insn;
+oprs_not_set_p (rtx x, rtx insn)
{
int i, j;
enum rtx_code code;
/* Mark things set by a CALL. */
static void
-mark_call (insn)
- rtx insn;
+mark_call (rtx insn)
{
if (! CONST_OR_PURE_CALL_P (insn))
record_last_mem_set_info (insn);
/* Mark things set by a SET. */
static void
-mark_set (pat, insn)
- rtx pat, insn;
+mark_set (rtx pat, rtx insn)
{
rtx dest = SET_DEST (pat);
|| GET_CODE (dest) == STRICT_LOW_PART)
dest = XEXP (dest, 0);
- if (GET_CODE (dest) == REG)
+ if (REG_P (dest))
SET_REGNO_REG_SET (reg_set_bitmap, REGNO (dest));
- else if (GET_CODE (dest) == MEM)
+ else if (MEM_P (dest))
record_last_mem_set_info (insn);
if (GET_CODE (SET_SRC (pat)) == CALL)
/* Record things set by a CLOBBER. */
static void
-mark_clobber (pat, insn)
- rtx pat, insn;
+mark_clobber (rtx pat, rtx insn)
{
rtx clob = XEXP (pat, 0);
while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART)
clob = XEXP (clob, 0);
- if (GET_CODE (clob) == REG)
+ if (REG_P (clob))
SET_REGNO_REG_SET (reg_set_bitmap, REGNO (clob));
else
record_last_mem_set_info (insn);
This data is used by oprs_not_set_p. */
static void
-mark_oprs_set (insn)
- rtx insn;
+mark_oprs_set (rtx insn)
{
rtx pat = PATTERN (insn);
int i;
}
\f
-/* Classic GCSE reaching definition support. */
-
-/* Allocate reaching def variables. */
-
-static void
-alloc_rd_mem (n_blocks, n_insns)
- int n_blocks, n_insns;
-{
- rd_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
- sbitmap_vector_zero (rd_kill, n_blocks);
-
- rd_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
- sbitmap_vector_zero (rd_gen, n_blocks);
+/* Compute copy/constant propagation working variables. */
- reaching_defs = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
- sbitmap_vector_zero (reaching_defs, n_blocks);
+/* Local properties of assignments. */
+static sbitmap *cprop_pavloc;
+static sbitmap *cprop_absaltered;
- rd_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
- sbitmap_vector_zero (rd_out, n_blocks);
-}
+/* Global properties of assignments (computed from the local properties). */
+static sbitmap *cprop_avin;
+static sbitmap *cprop_avout;
-/* Free reaching def variables. */
+/* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
+ basic blocks. N_SETS is the number of sets. */
static void
-free_rd_mem ()
+alloc_cprop_mem (int n_blocks, int n_sets)
{
- sbitmap_vector_free (rd_kill);
- sbitmap_vector_free (rd_gen);
- sbitmap_vector_free (reaching_defs);
- sbitmap_vector_free (rd_out);
+ cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
+ cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
+
+ cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
+ cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
}
-/* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
+/* Free vars used by copy/const propagation. */
static void
-handle_rd_kill_set (insn, regno, bb)
- rtx insn;
- int regno;
- basic_block bb;
+free_cprop_mem (void)
{
- struct reg_set *this_reg;
-
- for (this_reg = reg_set_table[regno]; this_reg; this_reg = this_reg ->next)
- if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn))
- SET_BIT (rd_kill[bb->index], INSN_CUID (this_reg->insn));
+ sbitmap_vector_free (cprop_pavloc);
+ sbitmap_vector_free (cprop_absaltered);
+ sbitmap_vector_free (cprop_avin);
+ sbitmap_vector_free (cprop_avout);
}
-/* Compute the set of kill's for reaching definitions. */
+/* For each block, compute whether X is transparent. X is either an
+ expression or an assignment [though we don't care which, for this context
+ an assignment is treated as an expression]. For each block where an
+ element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
+ bit in BMAP. */
static void
-compute_kill_rd ()
+compute_transp (rtx x, int indx, sbitmap *bmap, int set_p)
{
- int cuid;
- unsigned int regno;
- int i;
+ int i, j;
basic_block bb;
+ enum rtx_code code;
+ reg_set *r;
+ const char *fmt;
- /* For each block
- For each set bit in `gen' of the block (i.e each insn which
- generates a definition in the block)
- Call the reg set by the insn corresponding to that bit regx
- Look at the linked list starting at reg_set_table[regx]
- For each setting of regx in the linked list, which is not in
- this block
- Set the bit in `kill' corresponding to that insn. */
- FOR_EACH_BB (bb)
- for (cuid = 0; cuid < max_cuid; cuid++)
- if (TEST_BIT (rd_gen[bb->index], cuid))
- {
- rtx insn = CUID_INSN (cuid);
- rtx pat = PATTERN (insn);
+ /* repeat is used to turn tail-recursion into iteration since GCC
+ can't do it when there's no return value. */
+ repeat:
- if (GET_CODE (insn) == CALL_INSN)
+ if (x == 0)
+ return;
+
+ code = GET_CODE (x);
+ switch (code)
+ {
+ case REG:
+ if (set_p)
+ {
+ if (REGNO (x) < FIRST_PSEUDO_REGISTER)
{
- for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
- if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
- handle_rd_kill_set (insn, regno, bb);
+ FOR_EACH_BB (bb)
+ if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
+ SET_BIT (bmap[bb->index], indx);
}
-
- if (GET_CODE (pat) == PARALLEL)
+ else
{
- for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
- {
- enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i));
-
- if ((code == SET || code == CLOBBER)
- && GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG)
- handle_rd_kill_set (insn,
- REGNO (XEXP (XVECEXP (pat, 0, i), 0)),
- bb);
- }
+ for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
+ SET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
+ }
+ }
+ else
+ {
+ if (REGNO (x) < FIRST_PSEUDO_REGISTER)
+ {
+ FOR_EACH_BB (bb)
+ if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
+ RESET_BIT (bmap[bb->index], indx);
+ }
+ else
+ {
+ for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
+ RESET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
}
- else if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == REG)
- /* Each setting of this register outside of this block
- must be marked in the set of kills in this block. */
- handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), bb);
}
-}
-
-/* Compute the reaching definitions as in
- Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
- Chapter 10. It is the same algorithm as used for computing available
- expressions but applied to the gens and kills of reaching definitions. */
-
-static void
-compute_rd ()
-{
- int changed, passes;
- basic_block bb;
- FOR_EACH_BB (bb)
- sbitmap_copy (rd_out[bb->index] /*dst*/, rd_gen[bb->index] /*src*/);
+ return;
- passes = 0;
- changed = 1;
- while (changed)
- {
- changed = 0;
+ case MEM:
FOR_EACH_BB (bb)
{
- sbitmap_union_of_preds (reaching_defs[bb->index], rd_out, bb->index);
- changed |= sbitmap_union_of_diff_cg (rd_out[bb->index], rd_gen[bb->index],
- reaching_defs[bb->index], rd_kill[bb->index]);
- }
- passes++;
- }
+ rtx list_entry = canon_modify_mem_list[bb->index];
- if (gcse_file)
- fprintf (gcse_file, "reaching def computation: %d passes\n", passes);
-}
-\f
-/* Classic GCSE available expression support. */
+ while (list_entry)
+ {
+ rtx dest, dest_addr;
-/* Allocate memory for available expression computation. */
+ if (CALL_P (XEXP (list_entry, 0)))
+ {
+ if (set_p)
+ SET_BIT (bmap[bb->index], indx);
+ else
+ RESET_BIT (bmap[bb->index], indx);
+ break;
+ }
+ /* LIST_ENTRY must be an INSN of some kind that sets memory.
+ Examine each hunk of memory that is modified. */
-static void
-alloc_avail_expr_mem (n_blocks, n_exprs)
- int n_blocks, n_exprs;
-{
- ae_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
- sbitmap_vector_zero (ae_kill, n_blocks);
+ dest = XEXP (list_entry, 0);
+ list_entry = XEXP (list_entry, 1);
+ dest_addr = XEXP (list_entry, 0);
- ae_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
- sbitmap_vector_zero (ae_gen, n_blocks);
+ if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
+ x, rtx_addr_varies_p))
+ {
+ if (set_p)
+ SET_BIT (bmap[bb->index], indx);
+ else
+ RESET_BIT (bmap[bb->index], indx);
+ break;
+ }
+ list_entry = XEXP (list_entry, 1);
+ }
+ }
- ae_in = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
- sbitmap_vector_zero (ae_in, n_blocks);
+ x = XEXP (x, 0);
+ goto repeat;
- ae_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
- sbitmap_vector_zero (ae_out, n_blocks);
-}
+ case PC:
+ case CC0: /*FIXME*/
+ case CONST:
+ case CONST_INT:
+ case CONST_DOUBLE:
+ case CONST_VECTOR:
+ case SYMBOL_REF:
+ case LABEL_REF:
+ case ADDR_VEC:
+ case ADDR_DIFF_VEC:
+ return;
-static void
-free_avail_expr_mem ()
-{
- sbitmap_vector_free (ae_kill);
- sbitmap_vector_free (ae_gen);
- sbitmap_vector_free (ae_in);
- sbitmap_vector_free (ae_out);
+ default:
+ break;
+ }
+
+ for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
+ {
+ if (fmt[i] == 'e')
+ {
+ /* If we are about to do the last recursive call
+ needed at this level, change it into iteration.
+ This function is called enough to be worth it. */
+ if (i == 0)
+ {
+ x = XEXP (x, i);
+ goto repeat;
+ }
+
+ compute_transp (XEXP (x, i), indx, bmap, set_p);
+ }
+ else if (fmt[i] == 'E')
+ for (j = 0; j < XVECLEN (x, i); j++)
+ compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
+ }
}
-/* Compute the set of available expressions generated in each basic block. */
+/* Top level routine to do the dataflow analysis needed by copy/const
+ propagation. */
static void
-compute_ae_gen (expr_hash_table)
- struct hash_table *expr_hash_table;
+compute_cprop_data (void)
{
- unsigned int i;
- struct expr *expr;
- struct occr *occr;
-
- /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
- This is all we have to do because an expression is not recorded if it
- is not available, and the only expressions we want to work with are the
- ones that are recorded. */
- for (i = 0; i < expr_hash_table->size; i++)
- for (expr = expr_hash_table->table[i]; expr != 0; expr = expr->next_same_hash)
- for (occr = expr->avail_occr; occr != 0; occr = occr->next)
- SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index);
+ compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, &set_hash_table);
+ compute_available (cprop_pavloc, cprop_absaltered,
+ cprop_avout, cprop_avin);
}
+\f
+/* Copy/constant propagation. */
-/* Return nonzero if expression X is killed in BB. */
+/* Maximum number of register uses in an insn that we handle. */
+#define MAX_USES 8
-static int
-expr_killed_p (x, bb)
- rtx x;
- basic_block bb;
+/* Table of uses found in an insn.
+ Allocated statically to avoid alloc/free complexity and overhead. */
+static struct reg_use reg_use_table[MAX_USES];
+
+/* Index into `reg_use_table' while building it. */
+static int reg_use_count;
+
+/* Set up a list of register numbers used in INSN. The found uses are stored
+ in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
+ and contains the number of uses in the table upon exit.
+
+ ??? If a register appears multiple times we will record it multiple times.
+ This doesn't hurt anything but it will slow things down. */
+
+static void
+find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED)
{
int i, j;
enum rtx_code code;
const char *fmt;
+ rtx x = *xptr;
+ /* repeat is used to turn tail-recursion into iteration since GCC
+ can't do it when there's no return value. */
+ repeat:
if (x == 0)
- return 1;
+ return;
code = GET_CODE (x);
- switch (code)
+ if (REG_P (x))
{
- case REG:
- return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
-
- case MEM:
- if (load_killed_in_block_p (bb, get_max_uid () + 1, x, 0))
- return 1;
- else
- return expr_killed_p (XEXP (x, 0), bb);
-
- case PC:
- case CC0: /*FIXME*/
- case CONST:
- case CONST_INT:
- case CONST_DOUBLE:
- case CONST_VECTOR:
- case SYMBOL_REF:
- case LABEL_REF:
- case ADDR_VEC:
- case ADDR_DIFF_VEC:
- return 0;
+ if (reg_use_count == MAX_USES)
+ return;
- default:
- break;
+ reg_use_table[reg_use_count].reg_rtx = x;
+ reg_use_count++;
}
+ /* Recursively scan the operands of this expression. */
+
for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
{
if (fmt[i] == 'e')
needed at this level, change it into iteration.
This function is called enough to be worth it. */
if (i == 0)
- return expr_killed_p (XEXP (x, i), bb);
- else if (expr_killed_p (XEXP (x, i), bb))
- return 1;
+ {
+ x = XEXP (x, 0);
+ goto repeat;
+ }
+
+ find_used_regs (&XEXP (x, i), data);
}
else if (fmt[i] == 'E')
for (j = 0; j < XVECLEN (x, i); j++)
- if (expr_killed_p (XVECEXP (x, i, j), bb))
- return 1;
+ find_used_regs (&XVECEXP (x, i, j), data);
}
-
- return 0;
}
-/* Compute the set of available expressions killed in each basic block. */
+/* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
+ Returns nonzero is successful. */
-static void
-compute_ae_kill (ae_gen, ae_kill, expr_hash_table)
- sbitmap *ae_gen, *ae_kill;
- struct hash_table *expr_hash_table;
+static int
+try_replace_reg (rtx from, rtx to, rtx insn)
{
- basic_block bb;
- unsigned int i;
- struct expr *expr;
+ rtx note = find_reg_equal_equiv_note (insn);
+ rtx src = 0;
+ int success = 0;
+ rtx set = single_set (insn);
- FOR_EACH_BB (bb)
- for (i = 0; i < expr_hash_table->size; i++)
- for (expr = expr_hash_table->table[i]; expr; expr = expr->next_same_hash)
- {
- /* Skip EXPR if generated in this block. */
- if (TEST_BIT (ae_gen[bb->index], expr->bitmap_index))
- continue;
+ validate_replace_src_group (from, to, insn);
+ if (num_changes_pending () && apply_change_group ())
+ success = 1;
- if (expr_killed_p (expr->expr, bb))
- SET_BIT (ae_kill[bb->index], expr->bitmap_index);
- }
-}
-\f
-/* Actually perform the Classic GCSE optimizations. */
+ /* Try to simplify SET_SRC if we have substituted a constant. */
+ if (success && set && CONSTANT_P (to))
+ {
+ src = simplify_rtx (SET_SRC (set));
-/* Return nonzero if occurrence OCCR of expression EXPR reaches block BB.
+ if (src)
+ validate_change (insn, &SET_SRC (set), src, 0);
+ }
- CHECK_SELF_LOOP is nonzero if we should consider a block reaching itself
- as a positive reach. We want to do this when there are two computations
- of the expression in the block.
+ /* If there is already a NOTE, update the expression in it with our
+ replacement. */
+ if (note != 0)
+ XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
- VISITED is a pointer to a working buffer for tracking which BB's have
- been visited. It is NULL for the top-level call.
+ if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
+ {
+ /* If above failed and this is a single set, try to simplify the source of
+ the set given our substitution. We could perhaps try this for multiple
+ SETs, but it probably won't buy us anything. */
+ src = simplify_replace_rtx (SET_SRC (set), from, to);
- We treat reaching expressions that go through blocks containing the same
- reaching expression as "not reaching". E.g. if EXPR is generated in blocks
- 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
- 2 as not reaching. The intent is to improve the probability of finding
- only one reaching expression and to reduce register lifetimes by picking
- the closest such expression. */
+ if (!rtx_equal_p (src, SET_SRC (set))
+ && validate_change (insn, &SET_SRC (set), src, 0))
+ success = 1;
-static int
-expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited)
- struct occr *occr;
- struct expr *expr;
- basic_block bb;
- int check_self_loop;
- char *visited;
+ /* If we've failed to do replacement, have a single SET, don't already
+ have a note, and have no special SET, add a REG_EQUAL note to not
+ lose information. */
+ if (!success && note == 0 && set != 0
+ && GET_CODE (XEXP (set, 0)) != ZERO_EXTRACT
+ && GET_CODE (XEXP (set, 0)) != SIGN_EXTRACT)
+ note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
+ }
+
+ /* REG_EQUAL may get simplified into register.
+ We don't allow that. Remove that note. This code ought
+ not to happen, because previous code ought to synthesize
+ reg-reg move, but be on the safe side. */
+ if (note && REG_P (XEXP (note, 0)))
+ remove_note (insn, note);
+
+ return success;
+}
+
+/* Find a set of REGNOs that are available on entry to INSN's block. Returns
+ NULL no such set is found. */
+
+static struct expr *
+find_avail_set (int regno, rtx insn)
{
- edge pred;
+ /* SET1 contains the last set found that can be returned to the caller for
+ use in a substitution. */
+ struct expr *set1 = 0;
- for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
+ /* Loops are not possible here. To get a loop we would need two sets
+ available at the start of the block containing INSN. ie we would
+ need two sets like this available at the start of the block:
+
+ (set (reg X) (reg Y))
+ (set (reg Y) (reg X))
+
+ This can not happen since the set of (reg Y) would have killed the
+ set of (reg X) making it unavailable at the start of this block. */
+ while (1)
{
- basic_block pred_bb = pred->src;
+ rtx src;
+ struct expr *set = lookup_set (regno, &set_hash_table);
- if (visited[pred_bb->index])
- /* This predecessor has already been visited. Nothing to do. */
- ;
- else if (pred_bb == bb)
+ /* Find a set that is available at the start of the block
+ which contains INSN. */
+ while (set)
{
- /* BB loops on itself. */
- if (check_self_loop
- && TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index)
- && BLOCK_NUM (occr->insn) == pred_bb->index)
- return 1;
-
- visited[pred_bb->index] = 1;
+ if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
+ break;
+ set = next_set (regno, set);
}
- /* Ignore this predecessor if it kills the expression. */
- else if (TEST_BIT (ae_kill[pred_bb->index], expr->bitmap_index))
- visited[pred_bb->index] = 1;
-
- /* Does this predecessor generate this expression? */
- else if (TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index))
- {
- /* Is this the occurrence we're looking for?
- Note that there's only one generating occurrence per block
- so we just need to check the block number. */
- if (BLOCK_NUM (occr->insn) == pred_bb->index)
- return 1;
+ /* If no available set was found we've reached the end of the
+ (possibly empty) copy chain. */
+ if (set == 0)
+ break;
- visited[pred_bb->index] = 1;
- }
+ if (GET_CODE (set->expr) != SET)
+ abort ();
- /* Neither gen nor kill. */
- else
- {
- visited[pred_bb->index] = 1;
- if (expr_reaches_here_p_work (occr, expr, pred_bb, check_self_loop,
- visited))
+ src = SET_SRC (set->expr);
- return 1;
- }
- }
+ /* We know the set is available.
+ Now check that SRC is ANTLOC (i.e. none of the source operands
+ have changed since the start of the block).
- /* All paths have been checked. */
- return 0;
-}
+ If the source operand changed, we may still use it for the next
+ iteration of this loop, but we may not use it for substitutions. */
-/* This wrapper for expr_reaches_here_p_work() is to ensure that any
- memory allocated for that function is returned. */
+ if (gcse_constant_p (src) || oprs_not_set_p (src, insn))
+ set1 = set;
-static int
-expr_reaches_here_p (occr, expr, bb, check_self_loop)
- struct occr *occr;
- struct expr *expr;
- basic_block bb;
- int check_self_loop;
-{
- int rval;
- char *visited = (char *) xcalloc (last_basic_block, 1);
+ /* If the source of the set is anything except a register, then
+ we have reached the end of the copy chain. */
+ if (! REG_P (src))
+ break;
- rval = expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited);
+ /* Follow the copy chain, ie start another iteration of the loop
+ and see if we have an available copy into SRC. */
+ regno = REGNO (src);
+ }
- free (visited);
- return rval;
+ /* SET1 holds the last set that was available and anticipatable at
+ INSN. */
+ return set1;
}
-/* Return the instruction that computes EXPR that reaches INSN's basic block.
- If there is more than one such instruction, return NULL.
-
- Called only by handle_avail_expr. */
+/* Subroutine of cprop_insn that tries to propagate constants into
+ JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
+ it is the instruction that immediately precedes JUMP, and must be a
+ single SET of a register. FROM is what we will try to replace,
+ SRC is the constant we will try to substitute for it. Returns nonzero
+ if a change was made. */
-static rtx
-computing_insn (expr, insn)
- struct expr *expr;
- rtx insn;
+static int
+cprop_jump (basic_block bb, rtx setcc, rtx jump, rtx from, rtx src)
{
- basic_block bb = BLOCK_FOR_INSN (insn);
+ rtx new, set_src, note_src;
+ rtx set = pc_set (jump);
+ rtx note = find_reg_equal_equiv_note (jump);
- if (expr->avail_occr->next == NULL)
+ if (note)
{
- if (BLOCK_FOR_INSN (expr->avail_occr->insn) == bb)
- /* The available expression is actually itself
- (i.e. a loop in the flow graph) so do nothing. */
- return NULL;
+ note_src = XEXP (note, 0);
+ if (GET_CODE (note_src) == EXPR_LIST)
+ note_src = NULL_RTX;
+ }
+ else note_src = NULL_RTX;
+
+ /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
+ set_src = note_src ? note_src : SET_SRC (set);
- /* (FIXME) Case that we found a pattern that was created by
- a substitution that took place. */
- return expr->avail_occr->insn;
+ /* First substitute the SETCC condition into the JUMP instruction,
+ then substitute that given values into this expanded JUMP. */
+ if (setcc != NULL_RTX
+ && !modified_between_p (from, setcc, jump)
+ && !modified_between_p (src, setcc, jump))
+ {
+ rtx setcc_src;
+ rtx setcc_set = single_set (setcc);
+ rtx setcc_note = find_reg_equal_equiv_note (setcc);
+ setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST)
+ ? XEXP (setcc_note, 0) : SET_SRC (setcc_set);
+ set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set),
+ setcc_src);
}
else
- {
- /* Pattern is computed more than once.
- Search backwards from this insn to see how many of these
- computations actually reach this insn. */
- struct occr *occr;
- rtx insn_computes_expr = NULL;
- int can_reach = 0;
+ setcc = NULL_RTX;
- for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
- {
- if (BLOCK_FOR_INSN (occr->insn) == bb)
- {
- /* The expression is generated in this block.
- The only time we care about this is when the expression
- is generated later in the block [and thus there's a loop].
- We let the normal cse pass handle the other cases. */
- if (INSN_CUID (insn) < INSN_CUID (occr->insn)
- && expr_reaches_here_p (occr, expr, bb, 1))
- {
- can_reach++;
- if (can_reach > 1)
- return NULL;
+ new = simplify_replace_rtx (set_src, from, src);
- insn_computes_expr = occr->insn;
- }
- }
- else if (expr_reaches_here_p (occr, expr, bb, 0))
- {
- can_reach++;
- if (can_reach > 1)
- return NULL;
+ /* If no simplification can be made, then try the next register. */
+ if (rtx_equal_p (new, SET_SRC (set)))
+ return 0;
- insn_computes_expr = occr->insn;
- }
+ /* If this is now a no-op delete it, otherwise this must be a valid insn. */
+ if (new == pc_rtx)
+ delete_insn (jump);
+ else
+ {
+ /* Ensure the value computed inside the jump insn to be equivalent
+ to one computed by setcc. */
+ if (setcc && modified_in_p (new, setcc))
+ return 0;
+ if (! validate_change (jump, &SET_SRC (set), new, 0))
+ {
+ /* When (some) constants are not valid in a comparison, and there
+ are two registers to be replaced by constants before the entire
+ comparison can be folded into a constant, we need to keep
+ intermediate information in REG_EQUAL notes. For targets with
+ separate compare insns, such notes are added by try_replace_reg.
+ When we have a combined compare-and-branch instruction, however,
+ we need to attach a note to the branch itself to make this
+ optimization work. */
+
+ if (!rtx_equal_p (new, note_src))
+ set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new));
+ return 0;
}
- if (insn_computes_expr == NULL)
- abort ();
-
- return insn_computes_expr;
- }
-}
+ /* Remove REG_EQUAL note after simplification. */
+ if (note_src)
+ remove_note (jump, note);
-/* Return nonzero if the definition in DEF_INSN can reach INSN.
- Only called by can_disregard_other_sets. */
+ /* If this has turned into an unconditional jump,
+ then put a barrier after it so that the unreachable
+ code will be deleted. */
+ if (GET_CODE (SET_SRC (set)) == LABEL_REF)
+ emit_barrier_after (jump);
+ }
-static int
-def_reaches_here_p (insn, def_insn)
- rtx insn, def_insn;
-{
- rtx reg;
+#ifdef HAVE_cc0
+ /* Delete the cc0 setter. */
+ if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
+ delete_insn (setcc);
+#endif
- if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn)))
- return 1;
+ run_jump_opt_after_gcse = 1;
- if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn))
+ const_prop_count++;
+ if (gcse_file != NULL)
{
- if (INSN_CUID (def_insn) < INSN_CUID (insn))
- {
- if (GET_CODE (PATTERN (def_insn)) == PARALLEL)
- return 1;
- else if (GET_CODE (PATTERN (def_insn)) == CLOBBER)
- reg = XEXP (PATTERN (def_insn), 0);
- else if (GET_CODE (PATTERN (def_insn)) == SET)
- reg = SET_DEST (PATTERN (def_insn));
- else
- abort ();
-
- return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn);
- }
- else
- return 0;
+ fprintf (gcse_file,
+ "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
+ REGNO (from), INSN_UID (jump));
+ print_rtl (gcse_file, src);
+ fprintf (gcse_file, "\n");
}
+ purge_dead_edges (bb);
- return 0;
+ return 1;
}
-/* Return nonzero if *ADDR_THIS_REG can only have one value at INSN. The
- value returned is the number of definitions that reach INSN. Returning a
- value of zero means that [maybe] more than one definition reaches INSN and
- the caller can't perform whatever optimization it is trying. i.e. it is
- always safe to return zero. */
-
-static int
-can_disregard_other_sets (addr_this_reg, insn, for_combine)
- struct reg_set **addr_this_reg;
- rtx insn;
- int for_combine;
+static bool
+constprop_register (rtx insn, rtx from, rtx to, int alter_jumps)
{
- int number_of_reaching_defs = 0;
- struct reg_set *this_reg;
-
- for (this_reg = *addr_this_reg; this_reg != 0; this_reg = this_reg->next)
- if (def_reaches_here_p (insn, this_reg->insn))
- {
- number_of_reaching_defs++;
- /* Ignore parallels for now. */
- if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL)
- return 0;
+ rtx sset;
- if (!for_combine
- && (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER
- || ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
- SET_SRC (PATTERN (insn)))))
- /* A setting of the reg to a different value reaches INSN. */
- return 0;
+ /* Check for reg or cc0 setting instructions followed by
+ conditional branch instructions first. */
+ if (alter_jumps
+ && (sset = single_set (insn)) != NULL
+ && NEXT_INSN (insn)
+ && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
+ {
+ rtx dest = SET_DEST (sset);
+ if ((REG_P (dest) || CC0_P (dest))
+ && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
+ return 1;
+ }
- if (number_of_reaching_defs > 1)
- {
- /* If in this setting the value the register is being set to is
- equal to the previous value the register was set to and this
- setting reaches the insn we are trying to do the substitution
- on then we are ok. */
- if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER)
- return 0;
- else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
- SET_SRC (PATTERN (insn))))
- return 0;
- }
+ /* Handle normal insns next. */
+ if (GET_CODE (insn) == INSN
+ && try_replace_reg (from, to, insn))
+ return 1;
- *addr_this_reg = this_reg;
- }
+ /* Try to propagate a CONST_INT into a conditional jump.
+ We're pretty specific about what we will handle in this
+ code, we can extend this as necessary over time.
- return number_of_reaching_defs;
+ Right now the insn in question must look like
+ (set (pc) (if_then_else ...)) */
+ else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn))
+ return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
+ return 0;
}
-/* Expression computed by insn is available and the substitution is legal,
- so try to perform the substitution.
-
- The result is nonzero if any changes were made. */
+/* Perform constant and copy propagation on INSN.
+ The result is nonzero if a change was made. */
static int
-handle_avail_expr (insn, expr)
- rtx insn;
- struct expr *expr;
-{
- rtx pat, insn_computes_expr, expr_set;
- rtx to;
- struct reg_set *this_reg;
- int found_setting, use_src;
+cprop_insn (rtx insn, int alter_jumps)
+{
+ struct reg_use *reg_used;
int changed = 0;
+ rtx note;
- /* We only handle the case where one computation of the expression
- reaches this instruction. */
- insn_computes_expr = computing_insn (expr, insn);
- if (insn_computes_expr == NULL)
+ if (!INSN_P (insn))
return 0;
- expr_set = single_set (insn_computes_expr);
- if (!expr_set)
- abort ();
-
- found_setting = 0;
- use_src = 0;
-
- /* At this point we know only one computation of EXPR outside of this
- block reaches this insn. Now try to find a register that the
- expression is computed into. */
- if (GET_CODE (SET_SRC (expr_set)) == REG)
- {
- /* This is the case when the available expression that reaches
- here has already been handled as an available expression. */
- unsigned int regnum_for_replacing
- = REGNO (SET_SRC (expr_set));
-
- /* If the register was created by GCSE we can't use `reg_set_table',
- however we know it's set only once. */
- if (regnum_for_replacing >= max_gcse_regno
- /* If the register the expression is computed into is set only once,
- or only one set reaches this insn, we can use it. */
- || (((this_reg = reg_set_table[regnum_for_replacing]),
- this_reg->next == NULL)
- || can_disregard_other_sets (&this_reg, insn, 0)))
- {
- use_src = 1;
- found_setting = 1;
- }
- }
-
- if (!found_setting)
- {
- unsigned int regnum_for_replacing
- = REGNO (SET_DEST (expr_set));
- /* This shouldn't happen. */
- if (regnum_for_replacing >= max_gcse_regno)
- abort ();
+ reg_use_count = 0;
+ note_uses (&PATTERN (insn), find_used_regs, NULL);
- this_reg = reg_set_table[regnum_for_replacing];
+ note = find_reg_equal_equiv_note (insn);
- /* If the register the expression is computed into is set only once,
- or only one set reaches this insn, use it. */
- if (this_reg->next == NULL
- || can_disregard_other_sets (&this_reg, insn, 0))
- found_setting = 1;
- }
+ /* We may win even when propagating constants into notes. */
+ if (note)
+ find_used_regs (&XEXP (note, 0), NULL);
- if (found_setting)
+ for (reg_used = ®_use_table[0]; reg_use_count > 0;
+ reg_used++, reg_use_count--)
{
- pat = PATTERN (insn);
- if (use_src)
- to = SET_SRC (expr_set);
- else
- to = SET_DEST (expr_set);
- changed = validate_change (insn, &SET_SRC (pat), to, 0);
+ unsigned int regno = REGNO (reg_used->reg_rtx);
+ rtx pat, src;
+ struct expr *set;
- /* We should be able to ignore the return code from validate_change but
- to play it safe we check. */
- if (changed)
- {
- gcse_subst_count++;
- if (gcse_file != NULL)
- {
- fprintf (gcse_file, "GCSE: Replacing the source in insn %d with",
- INSN_UID (insn));
- fprintf (gcse_file, " reg %d %s insn %d\n",
- REGNO (to), use_src ? "from" : "set in",
- INSN_UID (insn_computes_expr));
- }
- }
- }
+ /* Ignore registers created by GCSE.
+ We do this because ... */
+ if (regno >= max_gcse_regno)
+ continue;
- /* The register that the expr is computed into is set more than once. */
- else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
- {
- /* Insert an insn after insnx that copies the reg set in insnx
- into a new pseudo register call this new register REGN.
- From insnb until end of basic block or until REGB is set
- replace all uses of REGB with REGN. */
- rtx new_insn;
+ /* If the register has already been set in this block, there's
+ nothing we can do. */
+ if (! oprs_not_set_p (reg_used->reg_rtx, insn))
+ continue;
- to = gen_reg_rtx (GET_MODE (SET_DEST (expr_set)));
+ /* Find an assignment that sets reg_used and is available
+ at the start of the block. */
+ set = find_avail_set (regno, insn);
+ if (! set)
+ continue;
- /* Generate the new insn. */
- /* ??? If the change fails, we return 0, even though we created
- an insn. I think this is ok. */
- new_insn
- = emit_insn_after (gen_rtx_SET (VOIDmode, to,
- SET_DEST (expr_set)),
- insn_computes_expr);
+ pat = set->expr;
+ /* ??? We might be able to handle PARALLELs. Later. */
+ if (GET_CODE (pat) != SET)
+ abort ();
- /* Keep register set table up to date. */
- record_one_set (REGNO (to), new_insn);
+ src = SET_SRC (pat);
- gcse_create_count++;
- if (gcse_file != NULL)
+ /* Constant propagation. */
+ if (gcse_constant_p (src))
{
- fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d",
- INSN_UID (NEXT_INSN (insn_computes_expr)),
- REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))));
- fprintf (gcse_file, ", computed in insn %d,\n",
- INSN_UID (insn_computes_expr));
- fprintf (gcse_file, " into newly allocated reg %d\n",
- REGNO (to));
+ if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps))
+ {
+ changed = 1;
+ const_prop_count++;
+ if (gcse_file != NULL)
+ {
+ fprintf (gcse_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
+ fprintf (gcse_file, "insn %d with constant ", INSN_UID (insn));
+ print_rtl (gcse_file, src);
+ fprintf (gcse_file, "\n");
+ }
+ if (INSN_DELETED_P (insn))
+ return 1;
+ }
}
-
- pat = PATTERN (insn);
-
- /* Do register replacement for INSN. */
- changed = validate_change (insn, &SET_SRC (pat),
- SET_DEST (PATTERN
- (NEXT_INSN (insn_computes_expr))),
- 0);
-
- /* We should be able to ignore the return code from validate_change but
- to play it safe we check. */
- if (changed)
+ else if (REG_P (src)
+ && REGNO (src) >= FIRST_PSEUDO_REGISTER
+ && REGNO (src) != regno)
{
- gcse_subst_count++;
- if (gcse_file != NULL)
+ if (try_replace_reg (reg_used->reg_rtx, src, insn))
{
- fprintf (gcse_file,
- "GCSE: Replacing the source in insn %d with reg %d ",
- INSN_UID (insn),
- REGNO (SET_DEST (PATTERN (NEXT_INSN
- (insn_computes_expr)))));
- fprintf (gcse_file, "set in insn %d\n",
- INSN_UID (insn_computes_expr));
+ changed = 1;
+ copy_prop_count++;
+ if (gcse_file != NULL)
+ {
+ fprintf (gcse_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
+ regno, INSN_UID (insn));
+ fprintf (gcse_file, " with reg %d\n", REGNO (src));
+ }
+
+ /* The original insn setting reg_used may or may not now be
+ deletable. We leave the deletion to flow. */
+ /* FIXME: If it turns out that the insn isn't deletable,
+ then we may have unnecessarily extended register lifetimes
+ and made things worse. */
}
}
}
return changed;
}
-/* Perform classic GCSE. This is called by one_classic_gcse_pass after all
- the dataflow analysis has been done.
-
- The result is nonzero if a change was made. */
+/* Like find_used_regs, but avoid recording uses that appear in
+ input-output contexts such as zero_extract or pre_dec. This
+ restricts the cases we consider to those for which local cprop
+ can legitimately make replacements. */
-static int
-classic_gcse ()
+static void
+local_cprop_find_used_regs (rtx *xptr, void *data)
{
- int changed;
- rtx insn;
- basic_block bb;
-
- /* Note we start at block 1. */
+ rtx x = *xptr;
- if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
- return 0;
+ if (x == 0)
+ return;
- changed = 0;
- FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
+ switch (GET_CODE (x))
{
- /* Reset tables used to keep track of what's still valid [since the
- start of the block]. */
- reset_opr_set_tables ();
+ case ZERO_EXTRACT:
+ case SIGN_EXTRACT:
+ case STRICT_LOW_PART:
+ return;
- for (insn = bb->head;
- insn != NULL && insn != NEXT_INSN (bb->end);
- insn = NEXT_INSN (insn))
- {
- /* Is insn of form (set (pseudo-reg) ...)? */
- if (GET_CODE (insn) == INSN
- && GET_CODE (PATTERN (insn)) == SET
- && GET_CODE (SET_DEST (PATTERN (insn))) == REG
- && REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER)
- {
- rtx pat = PATTERN (insn);
- rtx src = SET_SRC (pat);
- struct expr *expr;
+ case PRE_DEC:
+ case PRE_INC:
+ case POST_DEC:
+ case POST_INC:
+ case PRE_MODIFY:
+ case POST_MODIFY:
+ /* Can only legitimately appear this early in the context of
+ stack pushes for function arguments, but handle all of the
+ codes nonetheless. */
+ return;
- if (want_to_gcse_p (src)
- /* Is the expression recorded? */
- && ((expr = lookup_expr (src, &expr_hash_table)) != NULL)
- /* Is the expression available [at the start of the
- block]? */
- && TEST_BIT (ae_in[bb->index], expr->bitmap_index)
- /* Are the operands unchanged since the start of the
- block? */
- && oprs_not_set_p (src, insn))
- changed |= handle_avail_expr (insn, expr);
- }
+ case SUBREG:
+ /* Setting a subreg of a register larger than word_mode leaves
+ the non-written words unchanged. */
+ if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
+ return;
+ break;
- /* Keep track of everything modified by this insn. */
- /* ??? Need to be careful w.r.t. mods done to INSN. */
- if (INSN_P (insn))
- mark_oprs_set (insn);
- }
+ default:
+ break;
}
- return changed;
+ find_used_regs (xptr, data);
}
-/* Top level routine to perform one classic GCSE pass.
-
- Return nonzero if a change was made. */
+/* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
+ their REG_EQUAL notes need updating. */
-static int
-one_classic_gcse_pass (pass)
- int pass;
+static bool
+do_local_cprop (rtx x, rtx insn, int alter_jumps, rtx *libcall_sp)
{
- int changed = 0;
-
- gcse_subst_count = 0;
- gcse_create_count = 0;
-
- alloc_hash_table (max_cuid, &expr_hash_table, 0);
- alloc_rd_mem (last_basic_block, max_cuid);
- compute_hash_table (&expr_hash_table);
- if (gcse_file)
- dump_hash_table (gcse_file, "Expression", &expr_hash_table);
-
- if (expr_hash_table.n_elems > 0)
- {
- compute_kill_rd ();
- compute_rd ();
- alloc_avail_expr_mem (last_basic_block, expr_hash_table.n_elems);
- compute_ae_gen (&expr_hash_table);
- compute_ae_kill (ae_gen, ae_kill, &expr_hash_table);
- compute_available (ae_gen, ae_kill, ae_out, ae_in);
- changed = classic_gcse ();
- free_avail_expr_mem ();
- }
-
- free_rd_mem ();
- free_hash_table (&expr_hash_table);
-
- if (gcse_file)
- {
- fprintf (gcse_file, "\n");
- fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
- current_function_name, pass, bytes_used, gcse_subst_count);
- fprintf (gcse_file, "%d insns created\n", gcse_create_count);
- }
-
- return changed;
-}
-\f
-/* Compute copy/constant propagation working variables. */
-
-/* Local properties of assignments. */
-static sbitmap *cprop_pavloc;
-static sbitmap *cprop_absaltered;
-
-/* Global properties of assignments (computed from the local properties). */
-static sbitmap *cprop_avin;
-static sbitmap *cprop_avout;
-
-/* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
- basic blocks. N_SETS is the number of sets. */
-
-static void
-alloc_cprop_mem (n_blocks, n_sets)
- int n_blocks, n_sets;
-{
- cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
- cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
-
- cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
- cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
-}
-
-/* Free vars used by copy/const propagation. */
-
-static void
-free_cprop_mem ()
-{
- sbitmap_vector_free (cprop_pavloc);
- sbitmap_vector_free (cprop_absaltered);
- sbitmap_vector_free (cprop_avin);
- sbitmap_vector_free (cprop_avout);
-}
-
-/* For each block, compute whether X is transparent. X is either an
- expression or an assignment [though we don't care which, for this context
- an assignment is treated as an expression]. For each block where an
- element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
- bit in BMAP. */
-
-static void
-compute_transp (x, indx, bmap, set_p)
- rtx x;
- int indx;
- sbitmap *bmap;
- int set_p;
-{
- int i, j;
- basic_block bb;
- enum rtx_code code;
- reg_set *r;
- const char *fmt;
-
- /* repeat is used to turn tail-recursion into iteration since GCC
- can't do it when there's no return value. */
- repeat:
-
- if (x == 0)
- return;
-
- code = GET_CODE (x);
- switch (code)
- {
- case REG:
- if (set_p)
- {
- if (REGNO (x) < FIRST_PSEUDO_REGISTER)
- {
- FOR_EACH_BB (bb)
- if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
- SET_BIT (bmap[bb->index], indx);
- }
- else
- {
- for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
- SET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
- }
- }
- else
- {
- if (REGNO (x) < FIRST_PSEUDO_REGISTER)
- {
- FOR_EACH_BB (bb)
- if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
- RESET_BIT (bmap[bb->index], indx);
- }
- else
- {
- for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
- RESET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
- }
- }
-
- return;
-
- case MEM:
- FOR_EACH_BB (bb)
- {
- rtx list_entry = canon_modify_mem_list[bb->index];
-
- while (list_entry)
- {
- rtx dest, dest_addr;
-
- if (GET_CODE (XEXP (list_entry, 0)) == CALL_INSN)
- {
- if (set_p)
- SET_BIT (bmap[bb->index], indx);
- else
- RESET_BIT (bmap[bb->index], indx);
- break;
- }
- /* LIST_ENTRY must be an INSN of some kind that sets memory.
- Examine each hunk of memory that is modified. */
-
- dest = XEXP (list_entry, 0);
- list_entry = XEXP (list_entry, 1);
- dest_addr = XEXP (list_entry, 0);
-
- if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
- x, rtx_addr_varies_p))
- {
- if (set_p)
- SET_BIT (bmap[bb->index], indx);
- else
- RESET_BIT (bmap[bb->index], indx);
- break;
- }
- list_entry = XEXP (list_entry, 1);
- }
- }
-
- x = XEXP (x, 0);
- goto repeat;
-
- case PC:
- case CC0: /*FIXME*/
- case CONST:
- case CONST_INT:
- case CONST_DOUBLE:
- case CONST_VECTOR:
- case SYMBOL_REF:
- case LABEL_REF:
- case ADDR_VEC:
- case ADDR_DIFF_VEC:
- return;
-
- default:
- break;
- }
-
- for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
- {
- if (fmt[i] == 'e')
- {
- /* If we are about to do the last recursive call
- needed at this level, change it into iteration.
- This function is called enough to be worth it. */
- if (i == 0)
- {
- x = XEXP (x, i);
- goto repeat;
- }
-
- compute_transp (XEXP (x, i), indx, bmap, set_p);
- }
- else if (fmt[i] == 'E')
- for (j = 0; j < XVECLEN (x, i); j++)
- compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
- }
-}
-
-/* Top level routine to do the dataflow analysis needed by copy/const
- propagation. */
-
-static void
-compute_cprop_data ()
-{
- compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, &set_hash_table);
- compute_available (cprop_pavloc, cprop_absaltered,
- cprop_avout, cprop_avin);
-}
-\f
-/* Copy/constant propagation. */
-
-/* Maximum number of register uses in an insn that we handle. */
-#define MAX_USES 8
-
-/* Table of uses found in an insn.
- Allocated statically to avoid alloc/free complexity and overhead. */
-static struct reg_use reg_use_table[MAX_USES];
-
-/* Index into `reg_use_table' while building it. */
-static int reg_use_count;
-
-/* Set up a list of register numbers used in INSN. The found uses are stored
- in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
- and contains the number of uses in the table upon exit.
-
- ??? If a register appears multiple times we will record it multiple times.
- This doesn't hurt anything but it will slow things down. */
-
-static void
-find_used_regs (xptr, data)
- rtx *xptr;
- void *data ATTRIBUTE_UNUSED;
-{
- int i, j;
- enum rtx_code code;
- const char *fmt;
- rtx x = *xptr;
-
- /* repeat is used to turn tail-recursion into iteration since GCC
- can't do it when there's no return value. */
- repeat:
- if (x == 0)
- return;
-
- code = GET_CODE (x);
- if (REG_P (x))
- {
- if (reg_use_count == MAX_USES)
- return;
-
- reg_use_table[reg_use_count].reg_rtx = x;
- reg_use_count++;
- }
-
- /* Recursively scan the operands of this expression. */
-
- for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
- {
- if (fmt[i] == 'e')
- {
- /* If we are about to do the last recursive call
- needed at this level, change it into iteration.
- This function is called enough to be worth it. */
- if (i == 0)
- {
- x = XEXP (x, 0);
- goto repeat;
- }
-
- find_used_regs (&XEXP (x, i), data);
- }
- else if (fmt[i] == 'E')
- for (j = 0; j < XVECLEN (x, i); j++)
- find_used_regs (&XVECEXP (x, i, j), data);
- }
-}
-
-/* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
- Returns nonzero is successful. */
-
-static int
-try_replace_reg (from, to, insn)
- rtx from, to, insn;
-{
- rtx note = find_reg_equal_equiv_note (insn);
- rtx src = 0;
- int success = 0;
- rtx set = single_set (insn);
-
- validate_replace_src_group (from, to, insn);
- if (num_changes_pending () && apply_change_group ())
- success = 1;
-
- if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
- {
- /* If above failed and this is a single set, try to simplify the source of
- the set given our substitution. We could perhaps try this for multiple
- SETs, but it probably won't buy us anything. */
- src = simplify_replace_rtx (SET_SRC (set), from, to);
-
- if (!rtx_equal_p (src, SET_SRC (set))
- && validate_change (insn, &SET_SRC (set), src, 0))
- success = 1;
-
- /* If we've failed to do replacement, have a single SET, and don't already
- have a note, add a REG_EQUAL note to not lose information. */
- if (!success && note == 0 && set != 0)
- note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
- }
-
- /* If there is already a NOTE, update the expression in it with our
- replacement. */
- else if (note != 0)
- XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
-
- /* REG_EQUAL may get simplified into register.
- We don't allow that. Remove that note. This code ought
- not to happen, because previous code ought to synthesize
- reg-reg move, but be on the safe side. */
- if (note && REG_P (XEXP (note, 0)))
- remove_note (insn, note);
-
- return success;
-}
-
-/* Find a set of REGNOs that are available on entry to INSN's block. Returns
- NULL no such set is found. */
-
-static struct expr *
-find_avail_set (regno, insn)
- int regno;
- rtx insn;
-{
- /* SET1 contains the last set found that can be returned to the caller for
- use in a substitution. */
- struct expr *set1 = 0;
-
- /* Loops are not possible here. To get a loop we would need two sets
- available at the start of the block containing INSN. ie we would
- need two sets like this available at the start of the block:
-
- (set (reg X) (reg Y))
- (set (reg Y) (reg X))
-
- This can not happen since the set of (reg Y) would have killed the
- set of (reg X) making it unavailable at the start of this block. */
- while (1)
- {
- rtx src;
- struct expr *set = lookup_set (regno, &set_hash_table);
-
- /* Find a set that is available at the start of the block
- which contains INSN. */
- while (set)
- {
- if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
- break;
- set = next_set (regno, set);
- }
-
- /* If no available set was found we've reached the end of the
- (possibly empty) copy chain. */
- if (set == 0)
- break;
-
- if (GET_CODE (set->expr) != SET)
- abort ();
-
- src = SET_SRC (set->expr);
-
- /* We know the set is available.
- Now check that SRC is ANTLOC (i.e. none of the source operands
- have changed since the start of the block).
-
- If the source operand changed, we may still use it for the next
- iteration of this loop, but we may not use it for substitutions. */
-
- if (CONSTANT_P (src) || oprs_not_set_p (src, insn))
- set1 = set;
-
- /* If the source of the set is anything except a register, then
- we have reached the end of the copy chain. */
- if (GET_CODE (src) != REG)
- break;
-
- /* Follow the copy chain, ie start another iteration of the loop
- and see if we have an available copy into SRC. */
- regno = REGNO (src);
- }
-
- /* SET1 holds the last set that was available and anticipatable at
- INSN. */
- return set1;
-}
-
-/* Subroutine of cprop_insn that tries to propagate constants into
- JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
- it is the instruction that immediately precedes JUMP, and must be a
- single SET of a register. FROM is what we will try to replace,
- SRC is the constant we will try to substitute for it. Returns nonzero
- if a change was made. */
-
-static int
-cprop_jump (bb, setcc, jump, from, src)
- basic_block bb;
- rtx setcc;
- rtx jump;
- rtx from;
- rtx src;
-{
- rtx new, new_set;
- rtx set = pc_set (jump);
-
- /* First substitute in the INSN condition as the SET_SRC of the JUMP,
- then substitute that given values in this expanded JUMP. */
- if (setcc != NULL
- && !modified_between_p (from, setcc, jump)
- && !modified_between_p (src, setcc, jump))
- {
- rtx setcc_set = single_set (setcc);
- rtx note = find_reg_equal_equiv_note (setcc);
- /* Use REG_EQUAL note if available. */
- rtx setcc_set_src = (note == 0) ? SET_SRC (setcc_set) : XEXP (note, 0);
-
- new_set = simplify_replace_rtx (SET_SRC (set),
- SET_DEST (setcc_set),
- setcc_set_src);
- }
- else
- new_set = set;
-
- /* If NEW_SET is simplified down to either a label or a no-op, we
- don't have to replace FROM with SRC, but we still have to either
- turn JUMP to an unconditional branch or remove the no-op. This
- can happen if JUMP is simplified using the REG_EQUAL note in
- SETCC. */
- if (GET_CODE (new_set) == LABEL_REF || new_set == pc_rtx)
- new = new_set;
- else
- {
- new = simplify_replace_rtx (new_set, from, src);
-
- /* If no simplification can be made, then try the next
- register. */
- if (rtx_equal_p (new, new_set) || rtx_equal_p (new, SET_SRC (set)))
- return 0;
- }
-
- /* If this is now a no-op delete it, otherwise this must be a valid insn. */
- if (new == pc_rtx)
- delete_insn (jump);
- else
- {
- /* Ensure the value computed inside the jump insn to be equivalent
- to one computed by setcc. */
- if (setcc
- && modified_in_p (new, setcc))
- return 0;
- if (! validate_change (jump, &SET_SRC (set), new, 0))
- return 0;
-
- /* If this has turned into an unconditional jump,
- then put a barrier after it so that the unreachable
- code will be deleted. */
- if (GET_CODE (SET_SRC (set)) == LABEL_REF)
- emit_barrier_after (jump);
- }
-
-#ifdef HAVE_cc0
- /* Delete the cc0 setter. */
- if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
- delete_insn (setcc);
-#endif
-
- run_jump_opt_after_gcse = 1;
-
- const_prop_count++;
- if (gcse_file != NULL)
- {
- fprintf (gcse_file,
- "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
- REGNO (from), INSN_UID (jump));
- print_rtl (gcse_file, src);
- fprintf (gcse_file, "\n");
- }
- purge_dead_edges (bb);
-
- return 1;
-}
-
-static bool
-constprop_register (insn, from, to, alter_jumps)
- rtx insn;
- rtx from;
- rtx to;
- int alter_jumps;
-{
- rtx sset;
-
- /* Check for reg or cc0 setting instructions followed by
- conditional branch instructions first. */
- if (alter_jumps
- && (sset = single_set (insn)) != NULL
- && NEXT_INSN (insn)
- && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
- {
- rtx dest = SET_DEST (sset);
- if ((REG_P (dest) || CC0_P (dest))
- && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
- return 1;
- }
-
- /* Handle normal insns next. */
- if (GET_CODE (insn) == INSN
- && try_replace_reg (from, to, insn))
- return 1;
-
- /* Try to propagate a CONST_INT into a conditional jump.
- We're pretty specific about what we will handle in this
- code, we can extend this as necessary over time.
-
- Right now the insn in question must look like
- (set (pc) (if_then_else ...)) */
- else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn))
- return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
- return 0;
-}
-
-/* Perform constant and copy propagation on INSN.
- The result is nonzero if a change was made. */
-
-static int
-cprop_insn (insn, alter_jumps)
- rtx insn;
- int alter_jumps;
-{
- struct reg_use *reg_used;
- int changed = 0;
- rtx note;
-
- if (!INSN_P (insn))
- return 0;
-
- reg_use_count = 0;
- note_uses (&PATTERN (insn), find_used_regs, NULL);
-
- note = find_reg_equal_equiv_note (insn);
-
- /* We may win even when propagating constants into notes. */
- if (note)
- find_used_regs (&XEXP (note, 0), NULL);
-
- for (reg_used = ®_use_table[0]; reg_use_count > 0;
- reg_used++, reg_use_count--)
- {
- unsigned int regno = REGNO (reg_used->reg_rtx);
- rtx pat, src;
- struct expr *set;
-
- /* Ignore registers created by GCSE.
- We do this because ... */
- if (regno >= max_gcse_regno)
- continue;
-
- /* If the register has already been set in this block, there's
- nothing we can do. */
- if (! oprs_not_set_p (reg_used->reg_rtx, insn))
- continue;
-
- /* Find an assignment that sets reg_used and is available
- at the start of the block. */
- set = find_avail_set (regno, insn);
- if (! set)
- continue;
-
- pat = set->expr;
- /* ??? We might be able to handle PARALLELs. Later. */
- if (GET_CODE (pat) != SET)
- abort ();
-
- src = SET_SRC (pat);
-
- /* Constant propagation. */
- if (CONSTANT_P (src))
- {
- if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps))
- {
- changed = 1;
- const_prop_count++;
- if (gcse_file != NULL)
- {
- fprintf (gcse_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
- fprintf (gcse_file, "insn %d with constant ", INSN_UID (insn));
- print_rtl (gcse_file, src);
- fprintf (gcse_file, "\n");
- }
- }
- }
- else if (GET_CODE (src) == REG
- && REGNO (src) >= FIRST_PSEUDO_REGISTER
- && REGNO (src) != regno)
- {
- if (try_replace_reg (reg_used->reg_rtx, src, insn))
- {
- changed = 1;
- copy_prop_count++;
- if (gcse_file != NULL)
- {
- fprintf (gcse_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
- regno, INSN_UID (insn));
- fprintf (gcse_file, " with reg %d\n", REGNO (src));
- }
-
- /* The original insn setting reg_used may or may not now be
- deletable. We leave the deletion to flow. */
- /* FIXME: If it turns out that the insn isn't deletable,
- then we may have unnecessarily extended register lifetimes
- and made things worse. */
- }
- }
- }
-
- return changed;
-}
-
-/* Like find_used_regs, but avoid recording uses that appear in
- input-output contexts such as zero_extract or pre_dec. This
- restricts the cases we consider to those for which local cprop
- can legitimately make replacements. */
-
-static void
-local_cprop_find_used_regs (xptr, data)
- rtx *xptr;
- void *data;
-{
- rtx x = *xptr;
-
- if (x == 0)
- return;
-
- switch (GET_CODE (x))
- {
- case ZERO_EXTRACT:
- case SIGN_EXTRACT:
- case STRICT_LOW_PART:
- return;
-
- case PRE_DEC:
- case PRE_INC:
- case POST_DEC:
- case POST_INC:
- case PRE_MODIFY:
- case POST_MODIFY:
- /* Can only legitimately appear this early in the context of
- stack pushes for function arguments, but handle all of the
- codes nonetheless. */
- return;
-
- case SUBREG:
- /* Setting a subreg of a register larger than word_mode leaves
- the non-written words unchanged. */
- if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
- return;
- break;
-
- default:
- break;
- }
-
- find_used_regs (xptr, data);
-}
-
-/* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
- their REG_EQUAL notes need updating. */
-
-static bool
-do_local_cprop (x, insn, alter_jumps, libcall_sp)
- rtx x;
- rtx insn;
- int alter_jumps;
- rtx *libcall_sp;
-{
- rtx newreg = NULL, newcnst = NULL;
+ rtx newreg = NULL, newcnst = NULL;
/* Rule out USE instructions and ASM statements as we don't want to
change the hard registers mentioned. */
- if (GET_CODE (x) == REG
+ if (REG_P (x)
&& (REGNO (x) >= FIRST_PSEUDO_REGISTER
|| (GET_CODE (PATTERN (insn)) != USE
&& asm_noperands (PATTERN (insn)) < 0)))
if (l->in_libcall)
continue;
- if (CONSTANT_P (this_rtx)
- && GET_CODE (this_rtx) != CONSTANT_P_RTX)
+ if (gcse_constant_p (this_rtx))
newcnst = this_rtx;
if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
/* Don't copy propagate if it has attached REG_EQUIV note.
explicitly, it means address of parameter has been taken,
so we should not extend the lifetime of the pseudo. */
&& (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX))
- || GET_CODE (XEXP (note, 0)) != MEM))
+ || ! MEM_P (XEXP (note, 0))))
newreg = this_rtx;
}
if (newcnst && constprop_register (insn, x, newcnst, alter_jumps))
replaced with NEWVAL in INSN. Return true if all substitutions could
be made. */
static bool
-adjust_libcall_notes (oldreg, newval, insn, libcall_sp)
- rtx oldreg, newval, insn, *libcall_sp;
+adjust_libcall_notes (rtx oldreg, rtx newval, rtx insn, rtx *libcall_sp)
{
rtx end;
#define MAX_NESTED_LIBCALLS 9
static void
-local_cprop_pass (alter_jumps)
- int alter_jumps;
+local_cprop_pass (int alter_jumps)
{
rtx insn;
struct reg_use *reg_used;
rtx libcall_stack[MAX_NESTED_LIBCALLS + 1], *libcall_sp;
bool changed = false;
- cselib_init ();
+ cselib_init (false);
libcall_sp = &libcall_stack[MAX_NESTED_LIBCALLS];
*libcall_sp = 0;
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
changed = true;
break;
}
+ if (INSN_DELETED_P (insn))
+ break;
}
while (reg_use_count);
}
}
}
-/* Forward propagate copies. This includes copies and constants. Return
- nonzero if a change was made. */
+/* Forward propagate copies. This includes copies and constants. Return
+ nonzero if a change was made. */
+
+static int
+cprop (int alter_jumps)
+{
+ int changed;
+ basic_block bb;
+ rtx insn;
+
+ /* Note we start at block 1. */
+ if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
+ {
+ if (gcse_file != NULL)
+ fprintf (gcse_file, "\n");
+ return 0;
+ }
+
+ changed = 0;
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
+ {
+ /* Reset tables used to keep track of what's still valid [since the
+ start of the block]. */
+ reset_opr_set_tables ();
+
+ for (insn = BB_HEAD (bb);
+ insn != NULL && insn != NEXT_INSN (BB_END (bb));
+ insn = NEXT_INSN (insn))
+ if (INSN_P (insn))
+ {
+ changed |= cprop_insn (insn, alter_jumps);
+
+ /* Keep track of everything modified by this insn. */
+ /* ??? Need to be careful w.r.t. mods done to INSN. Don't
+ call mark_oprs_set if we turned the insn into a NOTE. */
+ if (! NOTE_P (insn))
+ mark_oprs_set (insn);
+ }
+ }
+
+ if (gcse_file != NULL)
+ fprintf (gcse_file, "\n");
+
+ return changed;
+}
+
+/* Similar to get_condition, only the resulting condition must be
+ valid at JUMP, instead of at EARLIEST.
+
+ This differs from noce_get_condition in ifcvt.c in that we prefer not to
+ settle for the condition variable in the jump instruction being integral.
+ We prefer to be able to record the value of a user variable, rather than
+ the value of a temporary used in a condition. This could be solved by
+ recording the value of *every* register scaned by canonicalize_condition,
+ but this would require some code reorganization. */
+
+rtx
+fis_get_condition (rtx jump)
+{
+ rtx cond, set, tmp, insn, earliest;
+ bool reverse;
+
+ if (! any_condjump_p (jump))
+ return NULL_RTX;
+
+ set = pc_set (jump);
+ cond = XEXP (SET_SRC (set), 0);
+
+ /* If this branches to JUMP_LABEL when the condition is false,
+ reverse the condition. */
+ reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
+ && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
+
+ /* Use canonicalize_condition to do the dirty work of manipulating
+ MODE_CC values and COMPARE rtx codes. */
+ tmp = canonicalize_condition (jump, cond, reverse, &earliest, NULL_RTX,
+ false);
+ if (!tmp)
+ return NULL_RTX;
+
+ /* Verify that the given condition is valid at JUMP by virtue of not
+ having been modified since EARLIEST. */
+ for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
+ if (INSN_P (insn) && modified_in_p (tmp, insn))
+ break;
+ if (insn == jump)
+ return tmp;
+
+ /* The condition was modified. See if we can get a partial result
+ that doesn't follow all the reversals. Perhaps combine can fold
+ them together later. */
+ tmp = XEXP (tmp, 0);
+ if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
+ return NULL_RTX;
+ tmp = canonicalize_condition (jump, cond, reverse, &earliest, tmp,
+ false);
+ if (!tmp)
+ return NULL_RTX;
+
+ /* For sanity's sake, re-validate the new result. */
+ for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
+ if (INSN_P (insn) && modified_in_p (tmp, insn))
+ return NULL_RTX;
+
+ return tmp;
+}
+
+/* Check the comparison COND to see if we can safely form an implicit set from
+ it. COND is either an EQ or NE comparison. */
+
+static bool
+implicit_set_cond_p (rtx cond)
+{
+ enum machine_mode mode = GET_MODE (XEXP (cond, 0));
+ rtx cst = XEXP (cond, 1);
+
+ /* We can't perform this optimization if either operand might be or might
+ contain a signed zero. */
+ if (HONOR_SIGNED_ZEROS (mode))
+ {
+ /* It is sufficient to check if CST is or contains a zero. We must
+ handle float, complex, and vector. If any subpart is a zero, then
+ the optimization can't be performed. */
+ /* ??? The complex and vector checks are not implemented yet. We just
+ always return zero for them. */
+ if (GET_CODE (cst) == CONST_DOUBLE)
+ {
+ REAL_VALUE_TYPE d;
+ REAL_VALUE_FROM_CONST_DOUBLE (d, cst);
+ if (REAL_VALUES_EQUAL (d, dconst0))
+ return 0;
+ }
+ else
+ return 0;
+ }
+
+ return gcse_constant_p (cst);
+}
+
+/* Find the implicit sets of a function. An "implicit set" is a constraint
+ on the value of a variable, implied by a conditional jump. For example,
+ following "if (x == 2)", the then branch may be optimized as though the
+ conditional performed an "explicit set", in this example, "x = 2". This
+ function records the set patterns that are implicit at the start of each
+ basic block. */
+
+static void
+find_implicit_sets (void)
+{
+ basic_block bb, dest;
+ unsigned int count;
+ rtx cond, new;
+
+ count = 0;
+ FOR_EACH_BB (bb)
+ /* Check for more than one successor. */
+ if (bb->succ && bb->succ->succ_next)
+ {
+ cond = fis_get_condition (BB_END (bb));
+
+ if (cond
+ && (GET_CODE (cond) == EQ || GET_CODE (cond) == NE)
+ && REG_P (XEXP (cond, 0))
+ && REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER
+ && implicit_set_cond_p (cond))
+ {
+ dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest
+ : FALLTHRU_EDGE (bb)->dest;
+
+ if (dest && ! dest->pred->pred_next
+ && dest != EXIT_BLOCK_PTR)
+ {
+ new = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
+ XEXP (cond, 1));
+ implicit_sets[dest->index] = new;
+ if (gcse_file)
+ {
+ fprintf(gcse_file, "Implicit set of reg %d in ",
+ REGNO (XEXP (cond, 0)));
+ fprintf(gcse_file, "basic block %d\n", dest->index);
+ }
+ count++;
+ }
+ }
+ }
+
+ if (gcse_file)
+ fprintf (gcse_file, "Found %d implicit sets\n", count);
+}
+
+/* Perform one copy/constant propagation pass.
+ PASS is the pass count. If CPROP_JUMPS is true, perform constant
+ propagation into conditional jumps. If BYPASS_JUMPS is true,
+ perform conditional jump bypassing optimizations. */
+
+static int
+one_cprop_pass (int pass, int cprop_jumps, int bypass_jumps)
+{
+ int changed = 0;
+
+ const_prop_count = 0;
+ copy_prop_count = 0;
+
+ local_cprop_pass (cprop_jumps);
+
+ /* Determine implicit sets. */
+ implicit_sets = xcalloc (last_basic_block, sizeof (rtx));
+ find_implicit_sets ();
+
+ alloc_hash_table (max_cuid, &set_hash_table, 1);
+ compute_hash_table (&set_hash_table);
+
+ /* Free implicit_sets before peak usage. */
+ free (implicit_sets);
+ implicit_sets = NULL;
+
+ if (gcse_file)
+ dump_hash_table (gcse_file, "SET", &set_hash_table);
+ if (set_hash_table.n_elems > 0)
+ {
+ alloc_cprop_mem (last_basic_block, set_hash_table.n_elems);
+ compute_cprop_data ();
+ changed = cprop (cprop_jumps);
+ if (bypass_jumps)
+ changed |= bypass_conditional_jumps ();
+ free_cprop_mem ();
+ }
+
+ free_hash_table (&set_hash_table);
+
+ if (gcse_file)
+ {
+ fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, ",
+ current_function_name (), pass, bytes_used);
+ fprintf (gcse_file, "%d const props, %d copy props\n\n",
+ const_prop_count, copy_prop_count);
+ }
+ /* Global analysis may get into infinite loops for unreachable blocks. */
+ if (changed && cprop_jumps)
+ delete_unreachable_blocks ();
+
+ return changed;
+}
+\f
+/* Bypass conditional jumps. */
+
+/* The value of last_basic_block at the beginning of the jump_bypass
+ pass. The use of redirect_edge_and_branch_force may introduce new
+ basic blocks, but the data flow analysis is only valid for basic
+ block indices less than bypass_last_basic_block. */
+
+static int bypass_last_basic_block;
+
+/* Find a set of REGNO to a constant that is available at the end of basic
+ block BB. Returns NULL if no such set is found. Based heavily upon
+ find_avail_set. */
+
+static struct expr *
+find_bypass_set (int regno, int bb)
+{
+ struct expr *result = 0;
+
+ for (;;)
+ {
+ rtx src;
+ struct expr *set = lookup_set (regno, &set_hash_table);
+
+ while (set)
+ {
+ if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
+ break;
+ set = next_set (regno, set);
+ }
+
+ if (set == 0)
+ break;
+
+ if (GET_CODE (set->expr) != SET)
+ abort ();
+
+ src = SET_SRC (set->expr);
+ if (gcse_constant_p (src))
+ result = set;
+
+ if (! REG_P (src))
+ break;
+
+ regno = REGNO (src);
+ }
+ return result;
+}
+
+
+/* Subroutine of bypass_block that checks whether a pseudo is killed by
+ any of the instructions inserted on an edge. Jump bypassing places
+ condition code setters on CFG edges using insert_insn_on_edge. This
+ function is required to check that our data flow analysis is still
+ valid prior to commit_edge_insertions. */
+
+static bool
+reg_killed_on_edge (rtx reg, edge e)
+{
+ rtx insn;
+
+ for (insn = e->insns.r; insn; insn = NEXT_INSN (insn))
+ if (INSN_P (insn) && reg_set_p (reg, insn))
+ return true;
+
+ return false;
+}
+
+/* Subroutine of bypass_conditional_jumps that attempts to bypass the given
+ basic block BB which has more than one predecessor. If not NULL, SETCC
+ is the first instruction of BB, which is immediately followed by JUMP_INSN
+ JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
+ Returns nonzero if a change was made.
+
+ During the jump bypassing pass, we may place copies of SETCC instructions
+ on CFG edges. The following routine must be careful to pay attention to
+ these inserted insns when performing its transformations. */
static int
-cprop (alter_jumps)
- int alter_jumps;
+bypass_block (basic_block bb, rtx setcc, rtx jump)
{
- int changed;
- basic_block bb;
- rtx insn;
+ rtx insn, note;
+ edge e, enext, edest;
+ int i, change;
+ int may_be_loop_header;
- /* Note we start at block 1. */
- if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
- {
- if (gcse_file != NULL)
- fprintf (gcse_file, "\n");
- return 0;
- }
+ insn = (setcc != NULL) ? setcc : jump;
- changed = 0;
- FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
+ /* Determine set of register uses in INSN. */
+ reg_use_count = 0;
+ note_uses (&PATTERN (insn), find_used_regs, NULL);
+ note = find_reg_equal_equiv_note (insn);
+ if (note)
+ find_used_regs (&XEXP (note, 0), NULL);
+
+ may_be_loop_header = false;
+ for (e = bb->pred; e; e = e->pred_next)
+ if (e->flags & EDGE_DFS_BACK)
+ {
+ may_be_loop_header = true;
+ break;
+ }
+
+ change = 0;
+ for (e = bb->pred; e; e = enext)
{
- /* Reset tables used to keep track of what's still valid [since the
- start of the block]. */
- reset_opr_set_tables ();
+ enext = e->pred_next;
+ if (e->flags & EDGE_COMPLEX)
+ continue;
- for (insn = bb->head;
- insn != NULL && insn != NEXT_INSN (bb->end);
- insn = NEXT_INSN (insn))
- if (INSN_P (insn))
- {
- changed |= cprop_insn (insn, alter_jumps);
+ /* We can't redirect edges from new basic blocks. */
+ if (e->src->index >= bypass_last_basic_block)
+ continue;
- /* Keep track of everything modified by this insn. */
- /* ??? Need to be careful w.r.t. mods done to INSN. Don't
- call mark_oprs_set if we turned the insn into a NOTE. */
- if (GET_CODE (insn) != NOTE)
- mark_oprs_set (insn);
- }
- }
+ /* The irreducible loops created by redirecting of edges entering the
+ loop from outside would decrease effectiveness of some of the following
+ optimizations, so prevent this. */
+ if (may_be_loop_header
+ && !(e->flags & EDGE_DFS_BACK))
+ continue;
- if (gcse_file != NULL)
- fprintf (gcse_file, "\n");
+ for (i = 0; i < reg_use_count; i++)
+ {
+ struct reg_use *reg_used = ®_use_table[i];
+ unsigned int regno = REGNO (reg_used->reg_rtx);
+ basic_block dest, old_dest;
+ struct expr *set;
+ rtx src, new;
- return changed;
-}
+ if (regno >= max_gcse_regno)
+ continue;
-/* Similar to get_condition, only the resulting condition must be
- valid at JUMP, instead of at EARLIEST.
+ set = find_bypass_set (regno, e->src->index);
- This differs from noce_get_condition in ifcvt.c in that we prefer not to
- settle for the condition variable in the jump instruction being integral.
- We prefer to be able to record the value of a user variable, rather than
- the value of a temporary used in a condition. This could be solved by
- recording the value of *every* register scaned by canonicalize_condition,
- but this would require some code reorganization. */
+ if (! set)
+ continue;
-static rtx
-fis_get_condition (jump)
- rtx jump;
-{
- rtx cond, set, tmp, insn, earliest;
- bool reverse;
+ /* Check the data flow is valid after edge insertions. */
+ if (e->insns.r && reg_killed_on_edge (reg_used->reg_rtx, e))
+ continue;
- if (! any_condjump_p (jump))
- return NULL_RTX;
+ src = SET_SRC (pc_set (jump));
- set = pc_set (jump);
- cond = XEXP (SET_SRC (set), 0);
+ if (setcc != NULL)
+ src = simplify_replace_rtx (src,
+ SET_DEST (PATTERN (setcc)),
+ SET_SRC (PATTERN (setcc)));
- /* If this branches to JUMP_LABEL when the condition is false,
- reverse the condition. */
- reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
- && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
+ new = simplify_replace_rtx (src, reg_used->reg_rtx,
+ SET_SRC (set->expr));
- /* Use canonicalize_condition to do the dirty work of manipulating
- MODE_CC values and COMPARE rtx codes. */
- tmp = canonicalize_condition (jump, cond, reverse, &earliest, NULL_RTX);
- if (!tmp)
- return NULL_RTX;
+ /* Jump bypassing may have already placed instructions on
+ edges of the CFG. We can't bypass an outgoing edge that
+ has instructions associated with it, as these insns won't
+ get executed if the incoming edge is redirected. */
- /* Verify that the given condition is valid at JUMP by virtue of not
- having been modified since EARLIEST. */
- for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
- if (INSN_P (insn) && modified_in_p (tmp, insn))
- break;
- if (insn == jump)
- return tmp;
+ if (new == pc_rtx)
+ {
+ edest = FALLTHRU_EDGE (bb);
+ dest = edest->insns.r ? NULL : edest->dest;
+ }
+ else if (GET_CODE (new) == LABEL_REF)
+ {
+ dest = BLOCK_FOR_INSN (XEXP (new, 0));
+ /* Don't bypass edges containing instructions. */
+ for (edest = bb->succ; edest; edest = edest->succ_next)
+ if (edest->dest == dest && edest->insns.r)
+ {
+ dest = NULL;
+ break;
+ }
+ }
+ else
+ dest = NULL;
- /* The condition was modified. See if we can get a partial result
- that doesn't follow all the reversals. Perhaps combine can fold
- them together later. */
- tmp = XEXP (tmp, 0);
- if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
- return NULL_RTX;
- tmp = canonicalize_condition (jump, cond, reverse, &earliest, tmp);
- if (!tmp)
- return NULL_RTX;
+ /* Avoid unification of the edge with other edges from original
+ branch. We would end up emitting the instruction on "both"
+ edges. */
- /* For sanity's sake, re-validate the new result. */
- for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
- if (INSN_P (insn) && modified_in_p (tmp, insn))
- return NULL_RTX;
+ if (dest && setcc && !CC0_P (SET_DEST (PATTERN (setcc))))
+ {
+ edge e2;
+ for (e2 = e->src->succ; e2; e2 = e2->succ_next)
+ if (e2->dest == dest)
+ {
+ dest = NULL;
+ break;
+ }
+ }
- return tmp;
+ old_dest = e->dest;
+ if (dest != NULL
+ && dest != old_dest
+ && dest != EXIT_BLOCK_PTR)
+ {
+ redirect_edge_and_branch_force (e, dest);
+
+ /* Copy the register setter to the redirected edge.
+ Don't copy CC0 setters, as CC0 is dead after jump. */
+ if (setcc)
+ {
+ rtx pat = PATTERN (setcc);
+ if (!CC0_P (SET_DEST (pat)))
+ insert_insn_on_edge (copy_insn (pat), e);
+ }
+
+ if (gcse_file != NULL)
+ {
+ fprintf (gcse_file, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
+ regno, INSN_UID (jump));
+ print_rtl (gcse_file, SET_SRC (set->expr));
+ fprintf (gcse_file, "\nBypass edge from %d->%d to %d\n",
+ e->src->index, old_dest->index, dest->index);
+ }
+ change = 1;
+ break;
+ }
+ }
+ }
+ return change;
}
-/* Find the implicit sets of a function. An "implicit set" is a constraint
- on the value of a variable, implied by a conditional jump. For example,
- following "if (x == 2)", the then branch may be optimized as though the
- conditional performed an "explicit set", in this example, "x = 2". This
- function records the set patterns that are implicit at the start of each
- basic block. */
+/* Find basic blocks with more than one predecessor that only contain a
+ single conditional jump. If the result of the comparison is known at
+ compile-time from any incoming edge, redirect that edge to the
+ appropriate target. Returns nonzero if a change was made.
-static void
-find_implicit_sets ()
+ This function is now mis-named, because we also handle indirect jumps. */
+
+static int
+bypass_conditional_jumps (void)
{
- basic_block bb, dest;
- unsigned int count;
- rtx cond, new;
+ basic_block bb;
+ int changed;
+ rtx setcc;
+ rtx insn;
+ rtx dest;
- count = 0;
- FOR_EACH_BB (bb)
- /* Check for more than one sucessor. */
- if (bb->succ && bb->succ->succ_next)
- {
- cond = fis_get_condition (bb->end);
+ /* Note we start at block 1. */
+ if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
+ return 0;
- if (cond
- && (GET_CODE (cond) == EQ || GET_CODE (cond) == NE)
- && GET_CODE (XEXP (cond, 0)) == REG
- && REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER
- && CONSTANT_P (XEXP (cond, 1)))
- {
- dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest
- : FALLTHRU_EDGE (bb)->dest;
+ bypass_last_basic_block = last_basic_block;
+ mark_dfs_back_edges ();
- if (dest && ! dest->pred->pred_next
- && dest != EXIT_BLOCK_PTR)
+ changed = 0;
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
+ EXIT_BLOCK_PTR, next_bb)
+ {
+ /* Check for more than one predecessor. */
+ if (bb->pred && bb->pred->pred_next)
+ {
+ setcc = NULL_RTX;
+ for (insn = BB_HEAD (bb);
+ insn != NULL && insn != NEXT_INSN (BB_END (bb));
+ insn = NEXT_INSN (insn))
+ if (GET_CODE (insn) == INSN)
{
- new = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
- XEXP (cond, 1));
- implicit_sets[dest->index] = new;
- if (gcse_file)
- {
- fprintf(gcse_file, "Implicit set of reg %d in ",
- REGNO (XEXP (cond, 0)));
- fprintf(gcse_file, "basic block %d\n", dest->index);
- }
- count++;
+ if (setcc)
+ break;
+ if (GET_CODE (PATTERN (insn)) != SET)
+ break;
+
+ dest = SET_DEST (PATTERN (insn));
+ if (REG_P (dest) || CC0_P (dest))
+ setcc = insn;
+ else
+ break;
}
- }
- }
+ else if (JUMP_P (insn))
+ {
+ if ((any_condjump_p (insn) || computed_jump_p (insn))
+ && onlyjump_p (insn))
+ changed |= bypass_block (bb, setcc, insn);
+ break;
+ }
+ else if (INSN_P (insn))
+ break;
+ }
+ }
- if (gcse_file)
- fprintf (gcse_file, "Found %d implicit sets\n", count);
+ /* If we bypassed any register setting insns, we inserted a
+ copy on the redirected edge. These need to be committed. */
+ if (changed)
+ commit_edge_insertions();
+
+ return changed;
}
+\f
+/* Compute PRE+LCM working variables. */
-/* Perform one copy/constant propagation pass.
- PASS is the pass count. If CPROP_JUMPS is true, perform constant
- propagation into conditional jumps. If BYPASS_JUMPS is true,
- perform conditional jump bypassing optimizations. */
+/* Local properties of expressions. */
+/* Nonzero for expressions that are transparent in the block. */
+static sbitmap *transp;
-static int
-one_cprop_pass (pass, cprop_jumps, bypass_jumps)
- int pass;
- int cprop_jumps;
- int bypass_jumps;
-{
- int changed = 0;
+/* Nonzero for expressions that are transparent at the end of the block.
+ This is only zero for expressions killed by abnormal critical edge
+ created by a calls. */
+static sbitmap *transpout;
- const_prop_count = 0;
- copy_prop_count = 0;
+/* Nonzero for expressions that are computed (available) in the block. */
+static sbitmap *comp;
- local_cprop_pass (cprop_jumps);
+/* Nonzero for expressions that are locally anticipatable in the block. */
+static sbitmap *antloc;
- /* Determine implicit sets. */
- implicit_sets = (rtx *) xcalloc (last_basic_block, sizeof (rtx));
- find_implicit_sets ();
+/* Nonzero for expressions where this block is an optimal computation
+ point. */
+static sbitmap *pre_optimal;
- alloc_hash_table (max_cuid, &set_hash_table, 1);
- compute_hash_table (&set_hash_table);
+/* Nonzero for expressions which are redundant in a particular block. */
+static sbitmap *pre_redundant;
- /* Free implicit_sets before peak usage. */
- free (implicit_sets);
- implicit_sets = NULL;
+/* Nonzero for expressions which should be inserted on a specific edge. */
+static sbitmap *pre_insert_map;
- if (gcse_file)
- dump_hash_table (gcse_file, "SET", &set_hash_table);
- if (set_hash_table.n_elems > 0)
- {
- alloc_cprop_mem (last_basic_block, set_hash_table.n_elems);
- compute_cprop_data ();
- changed = cprop (cprop_jumps);
- if (bypass_jumps)
- changed |= bypass_conditional_jumps ();
- free_cprop_mem ();
- }
+/* Nonzero for expressions which should be deleted in a specific block. */
+static sbitmap *pre_delete_map;
- free_hash_table (&set_hash_table);
+/* Contains the edge_list returned by pre_edge_lcm. */
+static struct edge_list *edge_list;
- if (gcse_file)
- {
- fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, ",
- current_function_name, pass, bytes_used);
- fprintf (gcse_file, "%d const props, %d copy props\n\n",
- const_prop_count, copy_prop_count);
- }
- /* Global analysis may get into infinite loops for unreachable blocks. */
- if (changed && cprop_jumps)
- delete_unreachable_blocks ();
+/* Redundant insns. */
+static sbitmap pre_redundant_insns;
- return changed;
+/* Allocate vars used for PRE analysis. */
+
+static void
+alloc_pre_mem (int n_blocks, int n_exprs)
+{
+ transp = sbitmap_vector_alloc (n_blocks, n_exprs);
+ comp = sbitmap_vector_alloc (n_blocks, n_exprs);
+ antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
+
+ pre_optimal = NULL;
+ pre_redundant = NULL;
+ pre_insert_map = NULL;
+ pre_delete_map = NULL;
+ ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
+
+ /* pre_insert and pre_delete are allocated later. */
}
-\f
-/* Bypass conditional jumps. */
-/* The value of last_basic_block at the beginning of the jump_bypass
- pass. The use of redirect_edge_and_branch_force may introduce new
- basic blocks, but the data flow analysis is only valid for basic
- block indices less than bypass_last_basic_block. */
+/* Free vars used for PRE analysis. */
-static int bypass_last_basic_block;
+static void
+free_pre_mem (void)
+{
+ sbitmap_vector_free (transp);
+ sbitmap_vector_free (comp);
-/* Find a set of REGNO to a constant that is available at the end of basic
- block BB. Returns NULL if no such set is found. Based heavily upon
- find_avail_set. */
+ /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
-static struct expr *
-find_bypass_set (regno, bb)
- int regno;
- int bb;
+ if (pre_optimal)
+ sbitmap_vector_free (pre_optimal);
+ if (pre_redundant)
+ sbitmap_vector_free (pre_redundant);
+ if (pre_insert_map)
+ sbitmap_vector_free (pre_insert_map);
+ if (pre_delete_map)
+ sbitmap_vector_free (pre_delete_map);
+
+ transp = comp = NULL;
+ pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
+}
+
+/* Top level routine to do the dataflow analysis needed by PRE. */
+
+static void
+compute_pre_data (void)
{
- struct expr *result = 0;
+ sbitmap trapping_expr;
+ basic_block bb;
+ unsigned int ui;
- for (;;)
- {
- rtx src;
- struct expr *set = lookup_set (regno, &set_hash_table);
+ compute_local_properties (transp, comp, antloc, &expr_hash_table);
+ sbitmap_vector_zero (ae_kill, last_basic_block);
- while (set)
- {
- if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
- break;
- set = next_set (regno, set);
- }
+ /* Collect expressions which might trap. */
+ trapping_expr = sbitmap_alloc (expr_hash_table.n_elems);
+ sbitmap_zero (trapping_expr);
+ for (ui = 0; ui < expr_hash_table.size; ui++)
+ {
+ struct expr *e;
+ for (e = expr_hash_table.table[ui]; e != NULL; e = e->next_same_hash)
+ if (may_trap_p (e->expr))
+ SET_BIT (trapping_expr, e->bitmap_index);
+ }
- if (set == 0)
- break;
+ /* Compute ae_kill for each basic block using:
- if (GET_CODE (set->expr) != SET)
- abort ();
+ ~(TRANSP | COMP)
+ */
- src = SET_SRC (set->expr);
- if (CONSTANT_P (src))
- result = set;
+ FOR_EACH_BB (bb)
+ {
+ edge e;
- if (GET_CODE (src) != REG)
- break;
+ /* If the current block is the destination of an abnormal edge, we
+ kill all trapping expressions because we won't be able to properly
+ place the instruction on the edge. So make them neither
+ anticipatable nor transparent. This is fairly conservative. */
+ for (e = bb->pred; e ; e = e->pred_next)
+ if (e->flags & EDGE_ABNORMAL)
+ {
+ sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
+ sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
+ break;
+ }
- regno = REGNO (src);
+ sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
+ sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
}
- return result;
+
+ edge_list = pre_edge_lcm (gcse_file, expr_hash_table.n_elems, transp, comp, antloc,
+ ae_kill, &pre_insert_map, &pre_delete_map);
+ sbitmap_vector_free (antloc);
+ antloc = NULL;
+ sbitmap_vector_free (ae_kill);
+ ae_kill = NULL;
+ sbitmap_free (trapping_expr);
}
+\f
+/* PRE utilities */
+/* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
+ block BB.
-/* Subroutine of bypass_conditional_jumps that attempts to bypass the given
- basic block BB which has more than one predecessor. If not NULL, SETCC
- is the first instruction of BB, which is immediately followed by JUMP_INSN
- JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
- Returns nonzero if a change was made. */
+ VISITED is a pointer to a working buffer for tracking which BB's have
+ been visited. It is NULL for the top-level call.
+
+ We treat reaching expressions that go through blocks containing the same
+ reaching expression as "not reaching". E.g. if EXPR is generated in blocks
+ 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
+ 2 as not reaching. The intent is to improve the probability of finding
+ only one reaching expression and to reduce register lifetimes by picking
+ the closest such expression. */
static int
-bypass_block (bb, setcc, jump)
- basic_block bb;
- rtx setcc, jump;
+pre_expr_reaches_here_p_work (basic_block occr_bb, struct expr *expr, basic_block bb, char *visited)
{
- rtx insn, note;
- edge e, enext;
- int i, change;
+ edge pred;
- insn = (setcc != NULL) ? setcc : jump;
+ for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
+ {
+ basic_block pred_bb = pred->src;
- /* Determine set of register uses in INSN. */
- reg_use_count = 0;
- note_uses (&PATTERN (insn), find_used_regs, NULL);
- note = find_reg_equal_equiv_note (insn);
- if (note)
- find_used_regs (&XEXP (note, 0), NULL);
+ if (pred->src == ENTRY_BLOCK_PTR
+ /* Has predecessor has already been visited? */
+ || visited[pred_bb->index])
+ ;/* Nothing to do. */
- change = 0;
- for (e = bb->pred; e; e = enext)
- {
- enext = e->pred_next;
- if (e->flags & EDGE_COMPLEX)
- continue;
+ /* Does this predecessor generate this expression? */
+ else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
+ {
+ /* Is this the occurrence we're looking for?
+ Note that there's only one generating occurrence per block
+ so we just need to check the block number. */
+ if (occr_bb == pred_bb)
+ return 1;
- /* We can't redirect edges from new basic blocks. */
- if (e->src->index >= bypass_last_basic_block)
- continue;
+ visited[pred_bb->index] = 1;
+ }
+ /* Ignore this predecessor if it kills the expression. */
+ else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
+ visited[pred_bb->index] = 1;
- for (i = 0; i < reg_use_count; i++)
+ /* Neither gen nor kill. */
+ else
{
- struct reg_use *reg_used = ®_use_table[i];
- unsigned int regno = REGNO (reg_used->reg_rtx);
- basic_block dest, old_dest;
- struct expr *set;
- rtx src, new;
+ visited[pred_bb->index] = 1;
+ if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
+ return 1;
+ }
+ }
+
+ /* All paths have been checked. */
+ return 0;
+}
- if (regno >= max_gcse_regno)
- continue;
+/* The wrapper for pre_expr_reaches_here_work that ensures that any
+ memory allocated for that function is returned. */
- set = find_bypass_set (regno, e->src->index);
+static int
+pre_expr_reaches_here_p (basic_block occr_bb, struct expr *expr, basic_block bb)
+{
+ int rval;
+ char *visited = xcalloc (last_basic_block, 1);
- if (! set)
- continue;
+ rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
- src = SET_SRC (pc_set (jump));
+ free (visited);
+ return rval;
+}
+\f
- if (setcc != NULL)
- src = simplify_replace_rtx (src,
- SET_DEST (PATTERN (setcc)),
- SET_SRC (PATTERN (setcc)));
+/* Given an expr, generate RTL which we can insert at the end of a BB,
+ or on an edge. Set the block number of any insns generated to
+ the value of BB. */
- new = simplify_replace_rtx (src, reg_used->reg_rtx,
- SET_SRC (set->expr));
+static rtx
+process_insert_insn (struct expr *expr)
+{
+ rtx reg = expr->reaching_reg;
+ rtx exp = copy_rtx (expr->expr);
+ rtx pat;
- if (new == pc_rtx)
- dest = FALLTHRU_EDGE (bb)->dest;
- else if (GET_CODE (new) == LABEL_REF)
- dest = BLOCK_FOR_INSN (XEXP (new, 0));
- else
- dest = NULL;
+ start_sequence ();
- old_dest = e->dest;
- if (dest != NULL
- && dest != old_dest
- && dest != EXIT_BLOCK_PTR)
- {
- redirect_edge_and_branch_force (e, dest);
+ /* If the expression is something that's an operand, like a constant,
+ just copy it to a register. */
+ if (general_operand (exp, GET_MODE (reg)))
+ emit_move_insn (reg, exp);
- /* Copy the register setter to the redirected edge.
- Don't copy CC0 setters, as CC0 is dead after jump. */
- if (setcc)
- {
- rtx pat = PATTERN (setcc);
- if (!CC0_P (SET_DEST (pat)))
- insert_insn_on_edge (copy_insn (pat), e);
- }
+ /* Otherwise, make a new insn to compute this expression and make sure the
+ insn will be recognized (this also adds any needed CLOBBERs). Copy the
+ expression to make sure we don't have any sharing issues. */
+ else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode, reg, exp))))
+ abort ();
- if (gcse_file != NULL)
- {
- fprintf (gcse_file, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
- regno, INSN_UID (jump));
- print_rtl (gcse_file, SET_SRC (set->expr));
- fprintf (gcse_file, "\nBypass edge from %d->%d to %d\n",
- e->src->index, old_dest->index, dest->index);
- }
- change = 1;
- break;
- }
- }
- }
- return change;
+ pat = get_insns ();
+ end_sequence ();
+
+ return pat;
}
-/* Find basic blocks with more than one predecessor that only contain a
- single conditional jump. If the result of the comparison is known at
- compile-time from any incoming edge, redirect that edge to the
- appropriate target. Returns nonzero if a change was made.
+/* Add EXPR to the end of basic block BB.
- This function is now mis-named, because we also handle indirect jumps. */
+ This is used by both the PRE and code hoisting.
-static int
-bypass_conditional_jumps ()
+ For PRE, we want to verify that the expr is either transparent
+ or locally anticipatable in the target block. This check makes
+ no sense for code hoisting. */
+
+static void
+insert_insn_end_bb (struct expr *expr, basic_block bb, int pre)
{
- basic_block bb;
- int changed;
- rtx setcc;
- rtx insn;
- rtx dest;
+ rtx insn = BB_END (bb);
+ rtx new_insn;
+ rtx reg = expr->reaching_reg;
+ int regno = REGNO (reg);
+ rtx pat, pat_end;
- /* Note we start at block 1. */
- if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
- return 0;
+ pat = process_insert_insn (expr);
+ if (pat == NULL_RTX || ! INSN_P (pat))
+ abort ();
- bypass_last_basic_block = last_basic_block;
+ pat_end = pat;
+ while (NEXT_INSN (pat_end) != NULL_RTX)
+ pat_end = NEXT_INSN (pat_end);
- changed = 0;
- FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
- EXIT_BLOCK_PTR, next_bb)
+ /* If the last insn is a jump, insert EXPR in front [taking care to
+ handle cc0, etc. properly]. Similarly we need to care trapping
+ instructions in presence of non-call exceptions. */
+
+ if (JUMP_P (insn)
+ || (GET_CODE (insn) == INSN
+ && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL))))
{
- /* Check for more than one predecessor. */
- if (bb->pred && bb->pred->pred_next)
- {
- setcc = NULL_RTX;
- for (insn = bb->head;
- insn != NULL && insn != NEXT_INSN (bb->end);
- insn = NEXT_INSN (insn))
- if (GET_CODE (insn) == INSN)
- {
- if (setcc)
- break;
- if (GET_CODE (PATTERN (insn)) != SET)
- break;
+#ifdef HAVE_cc0
+ rtx note;
+#endif
+ /* It should always be the case that we can put these instructions
+ anywhere in the basic block with performing PRE optimizations.
+ Check this. */
+ if (GET_CODE (insn) == INSN && pre
+ && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
+ && !TEST_BIT (transp[bb->index], expr->bitmap_index))
+ abort ();
- dest = SET_DEST (PATTERN (insn));
- if (REG_P (dest) || CC0_P (dest))
- setcc = insn;
- else
- break;
- }
- else if (GET_CODE (insn) == JUMP_INSN)
- {
- if ((any_condjump_p (insn) || computed_jump_p (insn))
- && onlyjump_p (insn))
- changed |= bypass_block (bb, setcc, insn);
- break;
- }
- else if (INSN_P (insn))
- break;
+ /* If this is a jump table, then we can't insert stuff here. Since
+ we know the previous real insn must be the tablejump, we insert
+ the new instruction just before the tablejump. */
+ if (GET_CODE (PATTERN (insn)) == ADDR_VEC
+ || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
+ insn = prev_real_insn (insn);
+
+#ifdef HAVE_cc0
+ /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
+ if cc0 isn't set. */
+ note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
+ if (note)
+ insn = XEXP (note, 0);
+ else
+ {
+ rtx maybe_cc0_setter = prev_nonnote_insn (insn);
+ if (maybe_cc0_setter
+ && INSN_P (maybe_cc0_setter)
+ && sets_cc0_p (PATTERN (maybe_cc0_setter)))
+ insn = maybe_cc0_setter;
}
+#endif
+ /* FIXME: What if something in cc0/jump uses value set in new insn? */
+ new_insn = emit_insn_before (pat, insn);
}
- /* If we bypassed any register setting insns, we inserted a
- copy on the redirected edge. These need to be committed. */
- if (changed)
- commit_edge_insertions();
+ /* Likewise if the last insn is a call, as will happen in the presence
+ of exception handling. */
+ else if (CALL_P (insn)
+ && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL)))
+ {
+ /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
+ we search backward and place the instructions before the first
+ parameter is loaded. Do this for everyone for consistency and a
+ presumption that we'll get better code elsewhere as well.
- return changed;
-}
-\f
-/* Compute PRE+LCM working variables. */
+ It should always be the case that we can put these instructions
+ anywhere in the basic block with performing PRE optimizations.
+ Check this. */
-/* Local properties of expressions. */
-/* Nonzero for expressions that are transparent in the block. */
-static sbitmap *transp;
+ if (pre
+ && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
+ && !TEST_BIT (transp[bb->index], expr->bitmap_index))
+ abort ();
-/* Nonzero for expressions that are transparent at the end of the block.
- This is only zero for expressions killed by abnormal critical edge
- created by a calls. */
-static sbitmap *transpout;
+ /* Since different machines initialize their parameter registers
+ in different orders, assume nothing. Collect the set of all
+ parameter registers. */
+ insn = find_first_parameter_load (insn, BB_HEAD (bb));
-/* Nonzero for expressions that are computed (available) in the block. */
-static sbitmap *comp;
+ /* If we found all the parameter loads, then we want to insert
+ before the first parameter load.
-/* Nonzero for expressions that are locally anticipatable in the block. */
-static sbitmap *antloc;
+ If we did not find all the parameter loads, then we might have
+ stopped on the head of the block, which could be a CODE_LABEL.
+ If we inserted before the CODE_LABEL, then we would be putting
+ the insn in the wrong basic block. In that case, put the insn
+ after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
+ while (LABEL_P (insn)
+ || NOTE_INSN_BASIC_BLOCK_P (insn))
+ insn = NEXT_INSN (insn);
-/* Nonzero for expressions where this block is an optimal computation
- point. */
-static sbitmap *pre_optimal;
+ new_insn = emit_insn_before (pat, insn);
+ }
+ else
+ new_insn = emit_insn_after (pat, insn);
-/* Nonzero for expressions which are redundant in a particular block. */
-static sbitmap *pre_redundant;
+ while (1)
+ {
+ if (INSN_P (pat))
+ {
+ add_label_notes (PATTERN (pat), new_insn);
+ note_stores (PATTERN (pat), record_set_info, pat);
+ }
+ if (pat == pat_end)
+ break;
+ pat = NEXT_INSN (pat);
+ }
-/* Nonzero for expressions which should be inserted on a specific edge. */
-static sbitmap *pre_insert_map;
+ gcse_create_count++;
+
+ if (gcse_file)
+ {
+ fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, ",
+ bb->index, INSN_UID (new_insn));
+ fprintf (gcse_file, "copying expression %d to reg %d\n",
+ expr->bitmap_index, regno);
+ }
+}
+
+/* Insert partially redundant expressions on edges in the CFG to make
+ the expressions fully redundant. */
+
+static int
+pre_edge_insert (struct edge_list *edge_list, struct expr **index_map)
+{
+ int e, i, j, num_edges, set_size, did_insert = 0;
+ sbitmap *inserted;
-/* Nonzero for expressions which should be deleted in a specific block. */
-static sbitmap *pre_delete_map;
+ /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
+ if it reaches any of the deleted expressions. */
-/* Contains the edge_list returned by pre_edge_lcm. */
-static struct edge_list *edge_list;
+ set_size = pre_insert_map[0]->size;
+ num_edges = NUM_EDGES (edge_list);
+ inserted = sbitmap_vector_alloc (num_edges, expr_hash_table.n_elems);
+ sbitmap_vector_zero (inserted, num_edges);
-/* Redundant insns. */
-static sbitmap pre_redundant_insns;
+ for (e = 0; e < num_edges; e++)
+ {
+ int indx;
+ basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
-/* Allocate vars used for PRE analysis. */
+ for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
+ {
+ SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
-static void
-alloc_pre_mem (n_blocks, n_exprs)
- int n_blocks, n_exprs;
-{
- transp = sbitmap_vector_alloc (n_blocks, n_exprs);
- comp = sbitmap_vector_alloc (n_blocks, n_exprs);
- antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
+ for (j = indx; insert && j < (int) expr_hash_table.n_elems; j++, insert >>= 1)
+ if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
+ {
+ struct expr *expr = index_map[j];
+ struct occr *occr;
- pre_optimal = NULL;
- pre_redundant = NULL;
- pre_insert_map = NULL;
- pre_delete_map = NULL;
- ae_in = NULL;
- ae_out = NULL;
- ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
+ /* Now look at each deleted occurrence of this expression. */
+ for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
+ {
+ if (! occr->deleted_p)
+ continue;
- /* pre_insert and pre_delete are allocated later. */
-}
+ /* Insert this expression on this edge if if it would
+ reach the deleted occurrence in BB. */
+ if (!TEST_BIT (inserted[e], j))
+ {
+ rtx insn;
+ edge eg = INDEX_EDGE (edge_list, e);
-/* Free vars used for PRE analysis. */
+ /* We can't insert anything on an abnormal and
+ critical edge, so we insert the insn at the end of
+ the previous block. There are several alternatives
+ detailed in Morgans book P277 (sec 10.5) for
+ handling this situation. This one is easiest for
+ now. */
-static void
-free_pre_mem ()
-{
- sbitmap_vector_free (transp);
- sbitmap_vector_free (comp);
+ if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
+ insert_insn_end_bb (index_map[j], bb, 0);
+ else
+ {
+ insn = process_insert_insn (index_map[j]);
+ insert_insn_on_edge (insn, eg);
+ }
- /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
+ if (gcse_file)
+ {
+ fprintf (gcse_file, "PRE/HOIST: edge (%d,%d), ",
+ bb->index,
+ INDEX_EDGE_SUCC_BB (edge_list, e)->index);
+ fprintf (gcse_file, "copy expression %d\n",
+ expr->bitmap_index);
+ }
- if (pre_optimal)
- sbitmap_vector_free (pre_optimal);
- if (pre_redundant)
- sbitmap_vector_free (pre_redundant);
- if (pre_insert_map)
- sbitmap_vector_free (pre_insert_map);
- if (pre_delete_map)
- sbitmap_vector_free (pre_delete_map);
- if (ae_in)
- sbitmap_vector_free (ae_in);
- if (ae_out)
- sbitmap_vector_free (ae_out);
+ update_ld_motion_stores (expr);
+ SET_BIT (inserted[e], j);
+ did_insert = 1;
+ gcse_create_count++;
+ }
+ }
+ }
+ }
+ }
- transp = comp = NULL;
- pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
- ae_in = ae_out = NULL;
+ sbitmap_vector_free (inserted);
+ return did_insert;
}
-/* Top level routine to do the dataflow analysis needed by PRE. */
+/* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
+ Given "old_reg <- expr" (INSN), instead of adding after it
+ reaching_reg <- old_reg
+ it's better to do the following:
+ reaching_reg <- expr
+ old_reg <- reaching_reg
+ because this way copy propagation can discover additional PRE
+ opportunities. But if this fails, we try the old way.
+ When "expr" is a store, i.e.
+ given "MEM <- old_reg", instead of adding after it
+ reaching_reg <- old_reg
+ it's better to add it before as follows:
+ reaching_reg <- old_reg
+ MEM <- reaching_reg. */
static void
-compute_pre_data ()
+pre_insert_copy_insn (struct expr *expr, rtx insn)
{
- sbitmap trapping_expr;
- basic_block bb;
- unsigned int ui;
-
- compute_local_properties (transp, comp, antloc, &expr_hash_table);
- sbitmap_vector_zero (ae_kill, last_basic_block);
+ rtx reg = expr->reaching_reg;
+ int regno = REGNO (reg);
+ int indx = expr->bitmap_index;
+ rtx pat = PATTERN (insn);
+ rtx set, new_insn;
+ rtx old_reg;
+ int i;
- /* Collect expressions which might trap. */
- trapping_expr = sbitmap_alloc (expr_hash_table.n_elems);
- sbitmap_zero (trapping_expr);
- for (ui = 0; ui < expr_hash_table.size; ui++)
+ /* This block matches the logic in hash_scan_insn. */
+ if (GET_CODE (pat) == SET)
+ set = pat;
+ else if (GET_CODE (pat) == PARALLEL)
{
- struct expr *e;
- for (e = expr_hash_table.table[ui]; e != NULL; e = e->next_same_hash)
- if (may_trap_p (e->expr))
- SET_BIT (trapping_expr, e->bitmap_index);
+ /* Search through the parallel looking for the set whose
+ source was the expression that we're interested in. */
+ set = NULL_RTX;
+ for (i = 0; i < XVECLEN (pat, 0); i++)
+ {
+ rtx x = XVECEXP (pat, 0, i);
+ if (GET_CODE (x) == SET
+ && expr_equiv_p (SET_SRC (x), expr->expr))
+ {
+ set = x;
+ break;
+ }
+ }
}
+ else
+ abort ();
- /* Compute ae_kill for each basic block using:
-
- ~(TRANSP | COMP)
+ if (REG_P (SET_DEST (set)))
+ {
+ old_reg = SET_DEST (set);
+ /* Check if we can modify the set destination in the original insn. */
+ if (validate_change (insn, &SET_DEST (set), reg, 0))
+ {
+ new_insn = gen_move_insn (old_reg, reg);
+ new_insn = emit_insn_after (new_insn, insn);
- This is significantly faster than compute_ae_kill. */
+ /* Keep register set table up to date. */
+ replace_one_set (REGNO (old_reg), insn, new_insn);
+ record_one_set (regno, insn);
+ }
+ else
+ {
+ new_insn = gen_move_insn (reg, old_reg);
+ new_insn = emit_insn_after (new_insn, insn);
- FOR_EACH_BB (bb)
+ /* Keep register set table up to date. */
+ record_one_set (regno, new_insn);
+ }
+ }
+ else /* This is possible only in case of a store to memory. */
{
- edge e;
+ old_reg = SET_SRC (set);
+ new_insn = gen_move_insn (reg, old_reg);
- /* If the current block is the destination of an abnormal edge, we
- kill all trapping expressions because we won't be able to properly
- place the instruction on the edge. So make them neither
- anticipatable nor transparent. This is fairly conservative. */
- for (e = bb->pred; e ; e = e->pred_next)
- if (e->flags & EDGE_ABNORMAL)
- {
- sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
- sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
- break;
- }
+ /* Check if we can modify the set source in the original insn. */
+ if (validate_change (insn, &SET_SRC (set), reg, 0))
+ new_insn = emit_insn_before (new_insn, insn);
+ else
+ new_insn = emit_insn_after (new_insn, insn);
- sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
- sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
+ /* Keep register set table up to date. */
+ record_one_set (regno, new_insn);
}
- edge_list = pre_edge_lcm (gcse_file, expr_hash_table.n_elems, transp, comp, antloc,
- ae_kill, &pre_insert_map, &pre_delete_map);
- sbitmap_vector_free (antloc);
- antloc = NULL;
- sbitmap_vector_free (ae_kill);
- ae_kill = NULL;
- sbitmap_free (trapping_expr);
+ gcse_create_count++;
+
+ if (gcse_file)
+ fprintf (gcse_file,
+ "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
+ BLOCK_NUM (insn), INSN_UID (new_insn), indx,
+ INSN_UID (insn), regno);
}
-\f
-/* PRE utilities */
-/* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
- block BB.
+/* Copy available expressions that reach the redundant expression
+ to `reaching_reg'. */
- VISITED is a pointer to a working buffer for tracking which BB's have
- been visited. It is NULL for the top-level call.
+static void
+pre_insert_copies (void)
+{
+ unsigned int i, added_copy;
+ struct expr *expr;
+ struct occr *occr;
+ struct occr *avail;
- We treat reaching expressions that go through blocks containing the same
- reaching expression as "not reaching". E.g. if EXPR is generated in blocks
- 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
- 2 as not reaching. The intent is to improve the probability of finding
- only one reaching expression and to reduce register lifetimes by picking
- the closest such expression. */
+ /* For each available expression in the table, copy the result to
+ `reaching_reg' if the expression reaches a deleted one.
-static int
-pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited)
- basic_block occr_bb;
- struct expr *expr;
- basic_block bb;
- char *visited;
-{
- edge pred;
+ ??? The current algorithm is rather brute force.
+ Need to do some profiling. */
- for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
- {
- basic_block pred_bb = pred->src;
+ for (i = 0; i < expr_hash_table.size; i++)
+ for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
+ {
+ /* If the basic block isn't reachable, PPOUT will be TRUE. However,
+ we don't want to insert a copy here because the expression may not
+ really be redundant. So only insert an insn if the expression was
+ deleted. This test also avoids further processing if the
+ expression wasn't deleted anywhere. */
+ if (expr->reaching_reg == NULL)
+ continue;
- if (pred->src == ENTRY_BLOCK_PTR
- /* Has predecessor has already been visited? */
- || visited[pred_bb->index])
- ;/* Nothing to do. */
+ /* Set when we add a copy for that expression. */
+ added_copy = 0;
- /* Does this predecessor generate this expression? */
- else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
- {
- /* Is this the occurrence we're looking for?
- Note that there's only one generating occurrence per block
- so we just need to check the block number. */
- if (occr_bb == pred_bb)
- return 1;
+ for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
+ {
+ if (! occr->deleted_p)
+ continue;
- visited[pred_bb->index] = 1;
- }
- /* Ignore this predecessor if it kills the expression. */
- else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
- visited[pred_bb->index] = 1;
+ for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
+ {
+ rtx insn = avail->insn;
- /* Neither gen nor kill. */
- else
- {
- visited[pred_bb->index] = 1;
- if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
- return 1;
- }
- }
+ /* No need to handle this one if handled already. */
+ if (avail->copied_p)
+ continue;
+
+ /* Don't handle this one if it's a redundant one. */
+ if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
+ continue;
+
+ /* Or if the expression doesn't reach the deleted one. */
+ if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
+ expr,
+ BLOCK_FOR_INSN (occr->insn)))
+ continue;
+
+ added_copy = 1;
+
+ /* Copy the result of avail to reaching_reg. */
+ pre_insert_copy_insn (expr, insn);
+ avail->copied_p = 1;
+ }
+ }
- /* All paths have been checked. */
- return 0;
+ if (added_copy)
+ update_ld_motion_stores (expr);
+ }
}
-/* The wrapper for pre_expr_reaches_here_work that ensures that any
- memory allocated for that function is returned. */
-
-static int
-pre_expr_reaches_here_p (occr_bb, expr, bb)
- basic_block occr_bb;
- struct expr *expr;
- basic_block bb;
+/* Emit move from SRC to DEST noting the equivalence with expression computed
+ in INSN. */
+static rtx
+gcse_emit_move_after (rtx src, rtx dest, rtx insn)
{
- int rval;
- char *visited = (char *) xcalloc (last_basic_block, 1);
+ rtx new;
+ rtx set = single_set (insn), set2;
+ rtx note;
+ rtx eqv;
- rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
+ /* This should never fail since we're creating a reg->reg copy
+ we've verified to be valid. */
- free (visited);
- return rval;
+ new = emit_insn_after (gen_move_insn (dest, src), insn);
+
+ /* Note the equivalence for local CSE pass. */
+ set2 = single_set (new);
+ if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
+ return new;
+ if ((note = find_reg_equal_equiv_note (insn)))
+ eqv = XEXP (note, 0);
+ else
+ eqv = SET_SRC (set);
+
+ set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (eqv));
+
+ return new;
}
-\f
-/* Given an expr, generate RTL which we can insert at the end of a BB,
- or on an edge. Set the block number of any insns generated to
- the value of BB. */
+/* Delete redundant computations.
+ Deletion is done by changing the insn to copy the `reaching_reg' of
+ the expression into the result of the SET. It is left to later passes
+ (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
-static rtx
-process_insert_insn (expr)
- struct expr *expr;
+ Returns nonzero if a change is made. */
+
+static int
+pre_delete (void)
{
- rtx reg = expr->reaching_reg;
- rtx exp = copy_rtx (expr->expr);
- rtx pat;
+ unsigned int i;
+ int changed;
+ struct expr *expr;
+ struct occr *occr;
- start_sequence ();
+ changed = 0;
+ for (i = 0; i < expr_hash_table.size; i++)
+ for (expr = expr_hash_table.table[i];
+ expr != NULL;
+ expr = expr->next_same_hash)
+ {
+ int indx = expr->bitmap_index;
- /* If the expression is something that's an operand, like a constant,
- just copy it to a register. */
- if (general_operand (exp, GET_MODE (reg)))
- emit_move_insn (reg, exp);
+ /* We only need to search antic_occr since we require
+ ANTLOC != 0. */
- /* Otherwise, make a new insn to compute this expression and make sure the
- insn will be recognized (this also adds any needed CLOBBERs). Copy the
- expression to make sure we don't have any sharing issues. */
- else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode, reg, exp))))
- abort ();
+ for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
+ {
+ rtx insn = occr->insn;
+ rtx set;
+ basic_block bb = BLOCK_FOR_INSN (insn);
- pat = get_insns ();
- end_sequence ();
+ /* We only delete insns that have a single_set. */
+ if (TEST_BIT (pre_delete_map[bb->index], indx)
+ && (set = single_set (insn)) != 0)
+ {
+ /* Create a pseudo-reg to store the result of reaching
+ expressions into. Get the mode for the new pseudo from
+ the mode of the original destination pseudo. */
+ if (expr->reaching_reg == NULL)
+ expr->reaching_reg
+ = gen_reg_rtx (GET_MODE (SET_DEST (set)));
- return pat;
+ gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
+ delete_insn (insn);
+ occr->deleted_p = 1;
+ SET_BIT (pre_redundant_insns, INSN_CUID (insn));
+ changed = 1;
+ gcse_subst_count++;
+
+ if (gcse_file)
+ {
+ fprintf (gcse_file,
+ "PRE: redundant insn %d (expression %d) in ",
+ INSN_UID (insn), indx);
+ fprintf (gcse_file, "bb %d, reaching reg is %d\n",
+ bb->index, REGNO (expr->reaching_reg));
+ }
+ }
+ }
+ }
+
+ return changed;
}
-/* Add EXPR to the end of basic block BB.
+/* Perform GCSE optimizations using PRE.
+ This is called by one_pre_gcse_pass after all the dataflow analysis
+ has been done.
- This is used by both the PRE and code hoisting.
+ This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
+ lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
+ Compiler Design and Implementation.
- For PRE, we want to verify that the expr is either transparent
- or locally anticipatable in the target block. This check makes
- no sense for code hoisting. */
+ ??? A new pseudo reg is created to hold the reaching expression. The nice
+ thing about the classical approach is that it would try to use an existing
+ reg. If the register can't be adequately optimized [i.e. we introduce
+ reload problems], one could add a pass here to propagate the new register
+ through the block.
-static void
-insert_insn_end_bb (expr, bb, pre)
- struct expr *expr;
- basic_block bb;
- int pre;
+ ??? We don't handle single sets in PARALLELs because we're [currently] not
+ able to copy the rest of the parallel when we insert copies to create full
+ redundancies from partial redundancies. However, there's no reason why we
+ can't handle PARALLELs in the cases where there are no partial
+ redundancies. */
+
+static int
+pre_gcse (void)
{
- rtx insn = bb->end;
- rtx new_insn;
- rtx reg = expr->reaching_reg;
- int regno = REGNO (reg);
- rtx pat, pat_end;
+ unsigned int i;
+ int did_insert, changed;
+ struct expr **index_map;
+ struct expr *expr;
- pat = process_insert_insn (expr);
- if (pat == NULL_RTX || ! INSN_P (pat))
- abort ();
+ /* Compute a mapping from expression number (`bitmap_index') to
+ hash table entry. */
- pat_end = pat;
- while (NEXT_INSN (pat_end) != NULL_RTX)
- pat_end = NEXT_INSN (pat_end);
+ index_map = xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
+ for (i = 0; i < expr_hash_table.size; i++)
+ for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
+ index_map[expr->bitmap_index] = expr;
- /* If the last insn is a jump, insert EXPR in front [taking care to
- handle cc0, etc. properly]. Similary we need to care trapping
- instructions in presence of non-call exceptions. */
+ /* Reset bitmap used to track which insns are redundant. */
+ pre_redundant_insns = sbitmap_alloc (max_cuid);
+ sbitmap_zero (pre_redundant_insns);
- if (GET_CODE (insn) == JUMP_INSN
- || (GET_CODE (insn) == INSN
- && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL))))
- {
-#ifdef HAVE_cc0
- rtx note;
-#endif
- /* It should always be the case that we can put these instructions
- anywhere in the basic block with performing PRE optimizations.
- Check this. */
- if (GET_CODE (insn) == INSN && pre
- && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
- && !TEST_BIT (transp[bb->index], expr->bitmap_index))
- abort ();
+ /* Delete the redundant insns first so that
+ - we know what register to use for the new insns and for the other
+ ones with reaching expressions
+ - we know which insns are redundant when we go to create copies */
- /* If this is a jump table, then we can't insert stuff here. Since
- we know the previous real insn must be the tablejump, we insert
- the new instruction just before the tablejump. */
- if (GET_CODE (PATTERN (insn)) == ADDR_VEC
- || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
- insn = prev_real_insn (insn);
+ changed = pre_delete ();
-#ifdef HAVE_cc0
- /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
- if cc0 isn't set. */
- note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
- if (note)
- insn = XEXP (note, 0);
- else
- {
- rtx maybe_cc0_setter = prev_nonnote_insn (insn);
- if (maybe_cc0_setter
- && INSN_P (maybe_cc0_setter)
- && sets_cc0_p (PATTERN (maybe_cc0_setter)))
- insn = maybe_cc0_setter;
- }
-#endif
- /* FIXME: What if something in cc0/jump uses value set in new insn? */
- new_insn = emit_insn_before (pat, insn);
- }
+ did_insert = pre_edge_insert (edge_list, index_map);
- /* Likewise if the last insn is a call, as will happen in the presence
- of exception handling. */
- else if (GET_CODE (insn) == CALL_INSN
- && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL)))
+ /* In other places with reaching expressions, copy the expression to the
+ specially allocated pseudo-reg that reaches the redundant expr. */
+ pre_insert_copies ();
+ if (did_insert)
{
- /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
- we search backward and place the instructions before the first
- parameter is loaded. Do this for everyone for consistency and a
- presumption that we'll get better code elsewhere as well.
+ commit_edge_insertions ();
+ changed = 1;
+ }
- It should always be the case that we can put these instructions
- anywhere in the basic block with performing PRE optimizations.
- Check this. */
+ free (index_map);
+ sbitmap_free (pre_redundant_insns);
+ return changed;
+}
- if (pre
- && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
- && !TEST_BIT (transp[bb->index], expr->bitmap_index))
- abort ();
+/* Top level routine to perform one PRE GCSE pass.
- /* Since different machines initialize their parameter registers
- in different orders, assume nothing. Collect the set of all
- parameter registers. */
- insn = find_first_parameter_load (insn, bb->head);
+ Return nonzero if a change was made. */
- /* If we found all the parameter loads, then we want to insert
- before the first parameter load.
+static int
+one_pre_gcse_pass (int pass)
+{
+ int changed = 0;
- If we did not find all the parameter loads, then we might have
- stopped on the head of the block, which could be a CODE_LABEL.
- If we inserted before the CODE_LABEL, then we would be putting
- the insn in the wrong basic block. In that case, put the insn
- after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
- while (GET_CODE (insn) == CODE_LABEL
- || NOTE_INSN_BASIC_BLOCK_P (insn))
- insn = NEXT_INSN (insn);
+ gcse_subst_count = 0;
+ gcse_create_count = 0;
- new_insn = emit_insn_before (pat, insn);
- }
- else
- new_insn = emit_insn_after (pat, insn);
+ alloc_hash_table (max_cuid, &expr_hash_table, 0);
+ add_noreturn_fake_exit_edges ();
+ if (flag_gcse_lm)
+ compute_ld_motion_mems ();
- while (1)
+ compute_hash_table (&expr_hash_table);
+ trim_ld_motion_mems ();
+ if (gcse_file)
+ dump_hash_table (gcse_file, "Expression", &expr_hash_table);
+
+ if (expr_hash_table.n_elems > 0)
{
- if (INSN_P (pat))
- {
- add_label_notes (PATTERN (pat), new_insn);
- note_stores (PATTERN (pat), record_set_info, pat);
- }
- if (pat == pat_end)
- break;
- pat = NEXT_INSN (pat);
+ alloc_pre_mem (last_basic_block, expr_hash_table.n_elems);
+ compute_pre_data ();
+ changed |= pre_gcse ();
+ free_edge_list (edge_list);
+ free_pre_mem ();
}
- gcse_create_count++;
+ free_ldst_mems ();
+ remove_fake_edges ();
+ free_hash_table (&expr_hash_table);
if (gcse_file)
{
- fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, ",
- bb->index, INSN_UID (new_insn));
- fprintf (gcse_file, "copying expression %d to reg %d\n",
- expr->bitmap_index, regno);
+ fprintf (gcse_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
+ current_function_name (), pass, bytes_used);
+ fprintf (gcse_file, "%d substs, %d insns created\n",
+ gcse_subst_count, gcse_create_count);
}
+
+ return changed;
}
+\f
+/* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
+ If notes are added to an insn which references a CODE_LABEL, the
+ LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
+ because the following loop optimization pass requires them. */
-/* Insert partially redundant expressions on edges in the CFG to make
- the expressions fully redundant. */
+/* ??? This is very similar to the loop.c add_label_notes function. We
+ could probably share code here. */
-static int
-pre_edge_insert (edge_list, index_map)
- struct edge_list *edge_list;
- struct expr **index_map;
+/* ??? If there was a jump optimization pass after gcse and before loop,
+ then we would not need to do this here, because jump would add the
+ necessary REG_LABEL notes. */
+
+static void
+add_label_notes (rtx x, rtx insn)
{
- int e, i, j, num_edges, set_size, did_insert = 0;
- sbitmap *inserted;
+ enum rtx_code code = GET_CODE (x);
+ int i, j;
+ const char *fmt;
- /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
- if it reaches any of the deleted expressions. */
+ if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
+ {
+ /* This code used to ignore labels that referred to dispatch tables to
+ avoid flow generating (slightly) worse code.
- set_size = pre_insert_map[0]->size;
- num_edges = NUM_EDGES (edge_list);
- inserted = sbitmap_vector_alloc (num_edges, expr_hash_table.n_elems);
- sbitmap_vector_zero (inserted, num_edges);
+ We no longer ignore such label references (see LABEL_REF handling in
+ mark_jump_label for additional information). */
- for (e = 0; e < num_edges; e++)
+ REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0),
+ REG_NOTES (insn));
+ if (LABEL_P (XEXP (x, 0)))
+ LABEL_NUSES (XEXP (x, 0))++;
+ return;
+ }
+
+ for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
{
- int indx;
- basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
+ if (fmt[i] == 'e')
+ add_label_notes (XEXP (x, i), insn);
+ else if (fmt[i] == 'E')
+ for (j = XVECLEN (x, i) - 1; j >= 0; j--)
+ add_label_notes (XVECEXP (x, i, j), insn);
+ }
+}
- for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
- {
- SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
+/* Compute transparent outgoing information for each block.
- for (j = indx; insert && j < (int) expr_hash_table.n_elems; j++, insert >>= 1)
- if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
- {
- struct expr *expr = index_map[j];
- struct occr *occr;
+ An expression is transparent to an edge unless it is killed by
+ the edge itself. This can only happen with abnormal control flow,
+ when the edge is traversed through a call. This happens with
+ non-local labels and exceptions.
- /* Now look at each deleted occurrence of this expression. */
- for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
- {
- if (! occr->deleted_p)
- continue;
+ This would not be necessary if we split the edge. While this is
+ normally impossible for abnormal critical edges, with some effort
+ it should be possible with exception handling, since we still have
+ control over which handler should be invoked. But due to increased
+ EH table sizes, this may not be worthwhile. */
- /* Insert this expression on this edge if if it would
- reach the deleted occurrence in BB. */
- if (!TEST_BIT (inserted[e], j))
- {
- rtx insn;
- edge eg = INDEX_EDGE (edge_list, e);
+static void
+compute_transpout (void)
+{
+ basic_block bb;
+ unsigned int i;
+ struct expr *expr;
- /* We can't insert anything on an abnormal and
- critical edge, so we insert the insn at the end of
- the previous block. There are several alternatives
- detailed in Morgans book P277 (sec 10.5) for
- handling this situation. This one is easiest for
- now. */
+ sbitmap_vector_ones (transpout, last_basic_block);
- if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
- insert_insn_end_bb (index_map[j], bb, 0);
- else
- {
- insn = process_insert_insn (index_map[j]);
- insert_insn_on_edge (insn, eg);
- }
+ FOR_EACH_BB (bb)
+ {
+ /* Note that flow inserted a nop a the end of basic blocks that
+ end in call instructions for reasons other than abnormal
+ control flow. */
+ if (! CALL_P (BB_END (bb)))
+ continue;
- if (gcse_file)
- {
- fprintf (gcse_file, "PRE/HOIST: edge (%d,%d), ",
- bb->index,
- INDEX_EDGE_SUCC_BB (edge_list, e)->index);
- fprintf (gcse_file, "copy expression %d\n",
- expr->bitmap_index);
- }
+ for (i = 0; i < expr_hash_table.size; i++)
+ for (expr = expr_hash_table.table[i]; expr ; expr = expr->next_same_hash)
+ if (MEM_P (expr->expr))
+ {
+ if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
+ && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
+ continue;
- update_ld_motion_stores (expr);
- SET_BIT (inserted[e], j);
- did_insert = 1;
- gcse_create_count++;
- }
- }
- }
- }
+ /* ??? Optimally, we would use interprocedural alias
+ analysis to determine if this mem is actually killed
+ by this call. */
+ RESET_BIT (transpout[bb->index], expr->bitmap_index);
+ }
}
-
- sbitmap_vector_free (inserted);
- return did_insert;
}
-/* Copy the result of INSN to REG. INDX is the expression number. */
+/* Code Hoisting variables and subroutines. */
+
+/* Very busy expressions. */
+static sbitmap *hoist_vbein;
+static sbitmap *hoist_vbeout;
+
+/* Hoistable expressions. */
+static sbitmap *hoist_exprs;
+
+/* ??? We could compute post dominators and run this algorithm in
+ reverse to perform tail merging, doing so would probably be
+ more effective than the tail merging code in jump.c.
+
+ It's unclear if tail merging could be run in parallel with
+ code hoisting. It would be nice. */
+
+/* Allocate vars used for code hoisting analysis. */
static void
-pre_insert_copy_insn (expr, insn)
- struct expr *expr;
- rtx insn;
+alloc_code_hoist_mem (int n_blocks, int n_exprs)
{
- rtx reg = expr->reaching_reg;
- int regno = REGNO (reg);
- int indx = expr->bitmap_index;
- rtx set = single_set (insn);
- rtx new_insn;
+ antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
+ transp = sbitmap_vector_alloc (n_blocks, n_exprs);
+ comp = sbitmap_vector_alloc (n_blocks, n_exprs);
- if (!set)
- abort ();
+ hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
+ hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
+ hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
+ transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
+}
- new_insn = emit_insn_after (gen_move_insn (reg, SET_DEST (set)), insn);
+/* Free vars used for code hoisting analysis. */
- /* Keep register set table up to date. */
- record_one_set (regno, new_insn);
+static void
+free_code_hoist_mem (void)
+{
+ sbitmap_vector_free (antloc);
+ sbitmap_vector_free (transp);
+ sbitmap_vector_free (comp);
- gcse_create_count++;
+ sbitmap_vector_free (hoist_vbein);
+ sbitmap_vector_free (hoist_vbeout);
+ sbitmap_vector_free (hoist_exprs);
+ sbitmap_vector_free (transpout);
- if (gcse_file)
- fprintf (gcse_file,
- "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
- BLOCK_NUM (insn), INSN_UID (new_insn), indx,
- INSN_UID (insn), regno);
- update_ld_motion_stores (expr);
+ free_dominance_info (CDI_DOMINATORS);
}
-/* Copy available expressions that reach the redundant expression
- to `reaching_reg'. */
+/* Compute the very busy expressions at entry/exit from each block.
+
+ An expression is very busy if all paths from a given point
+ compute the expression. */
static void
-pre_insert_copies ()
+compute_code_hoist_vbeinout (void)
{
- unsigned int i;
- struct expr *expr;
- struct occr *occr;
- struct occr *avail;
-
- /* For each available expression in the table, copy the result to
- `reaching_reg' if the expression reaches a deleted one.
+ int changed, passes;
+ basic_block bb;
- ??? The current algorithm is rather brute force.
- Need to do some profiling. */
+ sbitmap_vector_zero (hoist_vbeout, last_basic_block);
+ sbitmap_vector_zero (hoist_vbein, last_basic_block);
- for (i = 0; i < expr_hash_table.size; i++)
- for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
- {
- /* If the basic block isn't reachable, PPOUT will be TRUE. However,
- we don't want to insert a copy here because the expression may not
- really be redundant. So only insert an insn if the expression was
- deleted. This test also avoids further processing if the
- expression wasn't deleted anywhere. */
- if (expr->reaching_reg == NULL)
- continue;
+ passes = 0;
+ changed = 1;
- for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
- {
- if (! occr->deleted_p)
- continue;
+ while (changed)
+ {
+ changed = 0;
- for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
- {
- rtx insn = avail->insn;
+ /* We scan the blocks in the reverse order to speed up
+ the convergence. */
+ FOR_EACH_BB_REVERSE (bb)
+ {
+ changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index],
+ hoist_vbeout[bb->index], transp[bb->index]);
+ if (bb->next_bb != EXIT_BLOCK_PTR)
+ sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index);
+ }
- /* No need to handle this one if handled already. */
- if (avail->copied_p)
- continue;
+ passes++;
+ }
- /* Don't handle this one if it's a redundant one. */
- if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
- continue;
+ if (gcse_file)
+ fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes);
+}
- /* Or if the expression doesn't reach the deleted one. */
- if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
- expr,
- BLOCK_FOR_INSN (occr->insn)))
- continue;
+/* Top level routine to do the dataflow analysis needed by code hoisting. */
- /* Copy the result of avail to reaching_reg. */
- pre_insert_copy_insn (expr, insn);
- avail->copied_p = 1;
- }
- }
- }
+static void
+compute_code_hoist_data (void)
+{
+ compute_local_properties (transp, comp, antloc, &expr_hash_table);
+ compute_transpout ();
+ compute_code_hoist_vbeinout ();
+ calculate_dominance_info (CDI_DOMINATORS);
+ if (gcse_file)
+ fprintf (gcse_file, "\n");
}
-/* Emit move from SRC to DEST noting the equivalence with expression computed
- in INSN. */
-static rtx
-gcse_emit_move_after (src, dest, insn)
- rtx src, dest, insn;
+/* Determine if the expression identified by EXPR_INDEX would
+ reach BB unimpared if it was placed at the end of EXPR_BB.
+
+ It's unclear exactly what Muchnick meant by "unimpared". It seems
+ to me that the expression must either be computed or transparent in
+ *every* block in the path(s) from EXPR_BB to BB. Any other definition
+ would allow the expression to be hoisted out of loops, even if
+ the expression wasn't a loop invariant.
+
+ Contrast this to reachability for PRE where an expression is
+ considered reachable if *any* path reaches instead of *all*
+ paths. */
+
+static int
+hoist_expr_reaches_here_p (basic_block expr_bb, int expr_index, basic_block bb, char *visited)
{
- rtx new;
- rtx set = single_set (insn), set2;
- rtx note;
- rtx eqv;
+ edge pred;
+ int visited_allocated_locally = 0;
- /* This should never fail since we're creating a reg->reg copy
- we've verified to be valid. */
- new = emit_insn_after (gen_move_insn (dest, src), insn);
+ if (visited == NULL)
+ {
+ visited_allocated_locally = 1;
+ visited = xcalloc (last_basic_block, 1);
+ }
- /* Note the equivalence for local CSE pass. */
- set2 = single_set (new);
- if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
- return new;
- if ((note = find_reg_equal_equiv_note (insn)))
- eqv = XEXP (note, 0);
- else
- eqv = SET_SRC (set);
+ for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
+ {
+ basic_block pred_bb = pred->src;
- set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (eqv));
+ if (pred->src == ENTRY_BLOCK_PTR)
+ break;
+ else if (pred_bb == expr_bb)
+ continue;
+ else if (visited[pred_bb->index])
+ continue;
- return new;
-}
+ /* Does this predecessor generate this expression? */
+ else if (TEST_BIT (comp[pred_bb->index], expr_index))
+ break;
+ else if (! TEST_BIT (transp[pred_bb->index], expr_index))
+ break;
-/* Delete redundant computations.
- Deletion is done by changing the insn to copy the `reaching_reg' of
- the expression into the result of the SET. It is left to later passes
- (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
+ /* Not killed. */
+ else
+ {
+ visited[pred_bb->index] = 1;
+ if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
+ pred_bb, visited))
+ break;
+ }
+ }
+ if (visited_allocated_locally)
+ free (visited);
- Returns nonzero if a change is made. */
+ return (pred == NULL);
+}
+\f
+/* Actually perform code hoisting. */
-static int
-pre_delete ()
+static void
+hoist_code (void)
{
- unsigned int i;
- int changed;
+ basic_block bb, dominated;
+ basic_block *domby;
+ unsigned int domby_len;
+ unsigned int i,j;
+ struct expr **index_map;
struct expr *expr;
- struct occr *occr;
-
- changed = 0;
- for (i = 0; i < expr_hash_table.size; i++)
- for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
- {
- int indx = expr->bitmap_index;
- /* We only need to search antic_occr since we require
- ANTLOC != 0. */
-
- for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
- {
- rtx insn = occr->insn;
- rtx set;
- basic_block bb = BLOCK_FOR_INSN (insn);
+ sbitmap_vector_zero (hoist_exprs, last_basic_block);
- if (TEST_BIT (pre_delete_map[bb->index], indx))
- {
- set = single_set (insn);
- if (! set)
- abort ();
+ /* Compute a mapping from expression number (`bitmap_index') to
+ hash table entry. */
- /* Create a pseudo-reg to store the result of reaching
- expressions into. Get the mode for the new pseudo from
- the mode of the original destination pseudo. */
- if (expr->reaching_reg == NULL)
- expr->reaching_reg
- = gen_reg_rtx (GET_MODE (SET_DEST (set)));
+ index_map = xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
+ for (i = 0; i < expr_hash_table.size; i++)
+ for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
+ index_map[expr->bitmap_index] = expr;
- gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
- delete_insn (insn);
- occr->deleted_p = 1;
- SET_BIT (pre_redundant_insns, INSN_CUID (insn));
- changed = 1;
- gcse_subst_count++;
+ /* Walk over each basic block looking for potentially hoistable
+ expressions, nothing gets hoisted from the entry block. */
+ FOR_EACH_BB (bb)
+ {
+ int found = 0;
+ int insn_inserted_p;
- if (gcse_file)
- {
- fprintf (gcse_file,
- "PRE: redundant insn %d (expression %d) in ",
- INSN_UID (insn), indx);
- fprintf (gcse_file, "bb %d, reaching reg is %d\n",
- bb->index, REGNO (expr->reaching_reg));
- }
- }
- }
- }
+ domby_len = get_dominated_by (CDI_DOMINATORS, bb, &domby);
+ /* Examine each expression that is very busy at the exit of this
+ block. These are the potentially hoistable expressions. */
+ for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
+ {
+ int hoistable = 0;
- return changed;
-}
+ if (TEST_BIT (hoist_vbeout[bb->index], i)
+ && TEST_BIT (transpout[bb->index], i))
+ {
+ /* We've found a potentially hoistable expression, now
+ we look at every block BB dominates to see if it
+ computes the expression. */
+ for (j = 0; j < domby_len; j++)
+ {
+ dominated = domby[j];
+ /* Ignore self dominance. */
+ if (bb == dominated)
+ continue;
+ /* We've found a dominated block, now see if it computes
+ the busy expression and whether or not moving that
+ expression to the "beginning" of that block is safe. */
+ if (!TEST_BIT (antloc[dominated->index], i))
+ continue;
-/* Perform GCSE optimizations using PRE.
- This is called by one_pre_gcse_pass after all the dataflow analysis
- has been done.
+ /* Note if the expression would reach the dominated block
+ unimpared if it was placed at the end of BB.
- This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
- lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
- Compiler Design and Implementation.
+ Keep track of how many times this expression is hoistable
+ from a dominated block into BB. */
+ if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
+ hoistable++;
+ }
- ??? A new pseudo reg is created to hold the reaching expression. The nice
- thing about the classical approach is that it would try to use an existing
- reg. If the register can't be adequately optimized [i.e. we introduce
- reload problems], one could add a pass here to propagate the new register
- through the block.
+ /* If we found more than one hoistable occurrence of this
+ expression, then note it in the bitmap of expressions to
+ hoist. It makes no sense to hoist things which are computed
+ in only one BB, and doing so tends to pessimize register
+ allocation. One could increase this value to try harder
+ to avoid any possible code expansion due to register
+ allocation issues; however experiments have shown that
+ the vast majority of hoistable expressions are only movable
+ from two successors, so raising this threshold is likely
+ to nullify any benefit we get from code hoisting. */
+ if (hoistable > 1)
+ {
+ SET_BIT (hoist_exprs[bb->index], i);
+ found = 1;
+ }
+ }
+ }
+ /* If we found nothing to hoist, then quit now. */
+ if (! found)
+ {
+ free (domby);
+ continue;
+ }
- ??? We don't handle single sets in PARALLELs because we're [currently] not
- able to copy the rest of the parallel when we insert copies to create full
- redundancies from partial redundancies. However, there's no reason why we
- can't handle PARALLELs in the cases where there are no partial
- redundancies. */
+ /* Loop over all the hoistable expressions. */
+ for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
+ {
+ /* We want to insert the expression into BB only once, so
+ note when we've inserted it. */
+ insn_inserted_p = 0;
-static int
-pre_gcse ()
-{
- unsigned int i;
- int did_insert, changed;
- struct expr **index_map;
- struct expr *expr;
+ /* These tests should be the same as the tests above. */
+ if (TEST_BIT (hoist_vbeout[bb->index], i))
+ {
+ /* We've found a potentially hoistable expression, now
+ we look at every block BB dominates to see if it
+ computes the expression. */
+ for (j = 0; j < domby_len; j++)
+ {
+ dominated = domby[j];
+ /* Ignore self dominance. */
+ if (bb == dominated)
+ continue;
- /* Compute a mapping from expression number (`bitmap_index') to
- hash table entry. */
+ /* We've found a dominated block, now see if it computes
+ the busy expression and whether or not moving that
+ expression to the "beginning" of that block is safe. */
+ if (!TEST_BIT (antloc[dominated->index], i))
+ continue;
- index_map = (struct expr **) xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
- for (i = 0; i < expr_hash_table.size; i++)
- for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
- index_map[expr->bitmap_index] = expr;
+ /* The expression is computed in the dominated block and
+ it would be safe to compute it at the start of the
+ dominated block. Now we have to determine if the
+ expression would reach the dominated block if it was
+ placed at the end of BB. */
+ if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
+ {
+ struct expr *expr = index_map[i];
+ struct occr *occr = expr->antic_occr;
+ rtx insn;
+ rtx set;
- /* Reset bitmap used to track which insns are redundant. */
- pre_redundant_insns = sbitmap_alloc (max_cuid);
- sbitmap_zero (pre_redundant_insns);
+ /* Find the right occurrence of this expression. */
+ while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
+ occr = occr->next;
- /* Delete the redundant insns first so that
- - we know what register to use for the new insns and for the other
- ones with reaching expressions
- - we know which insns are redundant when we go to create copies */
+ /* Should never happen. */
+ if (!occr)
+ abort ();
- changed = pre_delete ();
+ insn = occr->insn;
- did_insert = pre_edge_insert (edge_list, index_map);
+ set = single_set (insn);
+ if (! set)
+ abort ();
- /* In other places with reaching expressions, copy the expression to the
- specially allocated pseudo-reg that reaches the redundant expr. */
- pre_insert_copies ();
- if (did_insert)
- {
- commit_edge_insertions ();
- changed = 1;
+ /* Create a pseudo-reg to store the result of reaching
+ expressions into. Get the mode for the new pseudo
+ from the mode of the original destination pseudo. */
+ if (expr->reaching_reg == NULL)
+ expr->reaching_reg
+ = gen_reg_rtx (GET_MODE (SET_DEST (set)));
+
+ gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
+ delete_insn (insn);
+ occr->deleted_p = 1;
+ if (!insn_inserted_p)
+ {
+ insert_insn_end_bb (index_map[i], bb, 0);
+ insn_inserted_p = 1;
+ }
+ }
+ }
+ }
+ }
+ free (domby);
}
free (index_map);
- sbitmap_free (pre_redundant_insns);
- return changed;
}
-/* Top level routine to perform one PRE GCSE pass.
+/* Top level routine to perform one code hoisting (aka unification) pass
Return nonzero if a change was made. */
static int
-one_pre_gcse_pass (pass)
- int pass;
+one_code_hoisting_pass (void)
{
int changed = 0;
- gcse_subst_count = 0;
- gcse_create_count = 0;
-
alloc_hash_table (max_cuid, &expr_hash_table, 0);
- add_noreturn_fake_exit_edges ();
- if (flag_gcse_lm)
- compute_ld_motion_mems ();
-
compute_hash_table (&expr_hash_table);
- trim_ld_motion_mems ();
if (gcse_file)
- dump_hash_table (gcse_file, "Expression", &expr_hash_table);
+ dump_hash_table (gcse_file, "Code Hosting Expressions", &expr_hash_table);
if (expr_hash_table.n_elems > 0)
{
- alloc_pre_mem (last_basic_block, expr_hash_table.n_elems);
- compute_pre_data ();
- changed |= pre_gcse ();
- free_edge_list (edge_list);
- free_pre_mem ();
+ alloc_code_hoist_mem (last_basic_block, expr_hash_table.n_elems);
+ compute_code_hoist_data ();
+ hoist_code ();
+ free_code_hoist_mem ();
}
- free_ldst_mems ();
- remove_fake_edges ();
free_hash_table (&expr_hash_table);
- if (gcse_file)
- {
- fprintf (gcse_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
- current_function_name, pass, bytes_used);
- fprintf (gcse_file, "%d substs, %d insns created\n",
- gcse_subst_count, gcse_create_count);
- }
-
return changed;
}
\f
-/* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
- If notes are added to an insn which references a CODE_LABEL, the
- LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
- because the following loop optimization pass requires them. */
-
-/* ??? This is very similar to the loop.c add_label_notes function. We
- could probably share code here. */
-
-/* ??? If there was a jump optimization pass after gcse and before loop,
- then we would not need to do this here, because jump would add the
- necessary REG_LABEL notes. */
-
-static void
-add_label_notes (x, insn)
- rtx x;
- rtx insn;
-{
- enum rtx_code code = GET_CODE (x);
- int i, j;
- const char *fmt;
-
- if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
- {
- /* This code used to ignore labels that referred to dispatch tables to
- avoid flow generating (slighly) worse code.
+/* Here we provide the things required to do store motion towards
+ the exit. In order for this to be effective, gcse also needed to
+ be taught how to move a load when it is kill only by a store to itself.
- We no longer ignore such label references (see LABEL_REF handling in
- mark_jump_label for additional information). */
+ int i;
+ float a[10];
- REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0),
- REG_NOTES (insn));
- if (LABEL_P (XEXP (x, 0)))
- LABEL_NUSES (XEXP (x, 0))++;
- return;
- }
+ void foo(float scale)
+ {
+ for (i=0; i<10; i++)
+ a[i] *= scale;
+ }
- for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
- {
- if (fmt[i] == 'e')
- add_label_notes (XEXP (x, i), insn);
- else if (fmt[i] == 'E')
- for (j = XVECLEN (x, i) - 1; j >= 0; j--)
- add_label_notes (XVECEXP (x, i, j), insn);
- }
-}
+ 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
+ the load out since its live around the loop, and stored at the bottom
+ of the loop.
-/* Compute transparent outgoing information for each block.
+ The 'Load Motion' referred to and implemented in this file is
+ an enhancement to gcse which when using edge based lcm, recognizes
+ this situation and allows gcse to move the load out of the loop.
- An expression is transparent to an edge unless it is killed by
- the edge itself. This can only happen with abnormal control flow,
- when the edge is traversed through a call. This happens with
- non-local labels and exceptions.
+ Once gcse has hoisted the load, store motion can then push this
+ load towards the exit, and we end up with no loads or stores of 'i'
+ in the loop. */
- This would not be necessary if we split the edge. While this is
- normally impossible for abnormal critical edges, with some effort
- it should be possible with exception handling, since we still have
- control over which handler should be invoked. But due to increased
- EH table sizes, this may not be worthwhile. */
+/* This will search the ldst list for a matching expression. If it
+ doesn't find one, we create one and initialize it. */
-static void
-compute_transpout ()
+static struct ls_expr *
+ldst_entry (rtx x)
{
- basic_block bb;
- unsigned int i;
- struct expr *expr;
-
- sbitmap_vector_ones (transpout, last_basic_block);
+ int do_not_record_p = 0;
+ struct ls_expr * ptr;
+ unsigned int hash;
- FOR_EACH_BB (bb)
- {
- /* Note that flow inserted a nop a the end of basic blocks that
- end in call instructions for reasons other than abnormal
- control flow. */
- if (GET_CODE (bb->end) != CALL_INSN)
- continue;
+ hash = hash_expr_1 (x, GET_MODE (x), & do_not_record_p);
- for (i = 0; i < expr_hash_table.size; i++)
- for (expr = expr_hash_table.table[i]; expr ; expr = expr->next_same_hash)
- if (GET_CODE (expr->expr) == MEM)
- {
- if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
- && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
- continue;
+ for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
+ if (ptr->hash_index == hash && expr_equiv_p (ptr->pattern, x))
+ return ptr;
- /* ??? Optimally, we would use interprocedural alias
- analysis to determine if this mem is actually killed
- by this call. */
- RESET_BIT (transpout[bb->index], expr->bitmap_index);
- }
- }
-}
+ ptr = xmalloc (sizeof (struct ls_expr));
-/* Removal of useless null pointer checks */
+ ptr->next = pre_ldst_mems;
+ ptr->expr = NULL;
+ ptr->pattern = x;
+ ptr->pattern_regs = NULL_RTX;
+ ptr->loads = NULL_RTX;
+ ptr->stores = NULL_RTX;
+ ptr->reaching_reg = NULL_RTX;
+ ptr->invalid = 0;
+ ptr->index = 0;
+ ptr->hash_index = hash;
+ pre_ldst_mems = ptr;
-/* Called via note_stores. X is set by SETTER. If X is a register we must
- invalidate nonnull_local and set nonnull_killed. DATA is really a
- `null_pointer_info *'.
+ return ptr;
+}
- We ignore hard registers. */
+/* Free up an individual ldst entry. */
static void
-invalidate_nonnull_info (x, setter, data)
- rtx x;
- rtx setter ATTRIBUTE_UNUSED;
- void *data;
+free_ldst_entry (struct ls_expr * ptr)
{
- unsigned int regno;
- struct null_pointer_info *npi = (struct null_pointer_info *) data;
-
- while (GET_CODE (x) == SUBREG)
- x = SUBREG_REG (x);
-
- /* Ignore anything that is not a register or is a hard register. */
- if (GET_CODE (x) != REG
- || REGNO (x) < npi->min_reg
- || REGNO (x) >= npi->max_reg)
- return;
-
- regno = REGNO (x) - npi->min_reg;
+ free_INSN_LIST_list (& ptr->loads);
+ free_INSN_LIST_list (& ptr->stores);
- RESET_BIT (npi->nonnull_local[npi->current_block->index], regno);
- SET_BIT (npi->nonnull_killed[npi->current_block->index], regno);
+ free (ptr);
}
-/* Do null-pointer check elimination for the registers indicated in
- NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
- they are not our responsibility to free. */
-
-static int
-delete_null_pointer_checks_1 (block_reg, nonnull_avin,
- nonnull_avout, npi)
- unsigned int *block_reg;
- sbitmap *nonnull_avin;
- sbitmap *nonnull_avout;
- struct null_pointer_info *npi;
-{
- basic_block bb, current_block;
- sbitmap *nonnull_local = npi->nonnull_local;
- sbitmap *nonnull_killed = npi->nonnull_killed;
- int something_changed = 0;
-
- /* Compute local properties, nonnull and killed. A register will have
- the nonnull property if at the end of the current block its value is
- known to be nonnull. The killed property indicates that somewhere in
- the block any information we had about the register is killed.
-
- Note that a register can have both properties in a single block. That
- indicates that it's killed, then later in the block a new value is
- computed. */
- sbitmap_vector_zero (nonnull_local, last_basic_block);
- sbitmap_vector_zero (nonnull_killed, last_basic_block);
-
- FOR_EACH_BB (current_block)
- {
- rtx insn, stop_insn;
-
- /* Set the current block for invalidate_nonnull_info. */
- npi->current_block = current_block;
-
- /* Scan each insn in the basic block looking for memory references and
- register sets. */
- stop_insn = NEXT_INSN (current_block->end);
- for (insn = current_block->head;
- insn != stop_insn;
- insn = NEXT_INSN (insn))
- {
- rtx set;
- rtx reg;
-
- /* Ignore anything that is not a normal insn. */
- if (! INSN_P (insn))
- continue;
-
- /* Basically ignore anything that is not a simple SET. We do have
- to make sure to invalidate nonnull_local and set nonnull_killed
- for such insns though. */
- set = single_set (insn);
- if (!set)
- {
- note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
- continue;
- }
-
- /* See if we've got a usable memory load. We handle it first
- in case it uses its address register as a dest (which kills
- the nonnull property). */
- if (GET_CODE (SET_SRC (set)) == MEM
- && GET_CODE ((reg = XEXP (SET_SRC (set), 0))) == REG
- && REGNO (reg) >= npi->min_reg
- && REGNO (reg) < npi->max_reg)
- SET_BIT (nonnull_local[current_block->index],
- REGNO (reg) - npi->min_reg);
-
- /* Now invalidate stuff clobbered by this insn. */
- note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
-
- /* And handle stores, we do these last since any sets in INSN can
- not kill the nonnull property if it is derived from a MEM
- appearing in a SET_DEST. */
- if (GET_CODE (SET_DEST (set)) == MEM
- && GET_CODE ((reg = XEXP (SET_DEST (set), 0))) == REG
- && REGNO (reg) >= npi->min_reg
- && REGNO (reg) < npi->max_reg)
- SET_BIT (nonnull_local[current_block->index],
- REGNO (reg) - npi->min_reg);
- }
- }
-
- /* Now compute global properties based on the local properties. This
- is a classic global availability algorithm. */
- compute_available (nonnull_local, nonnull_killed,
- nonnull_avout, nonnull_avin);
+/* Free up all memory associated with the ldst list. */
- /* Now look at each bb and see if it ends with a compare of a value
- against zero. */
- FOR_EACH_BB (bb)
+static void
+free_ldst_mems (void)
+{
+ while (pre_ldst_mems)
{
- rtx last_insn = bb->end;
- rtx condition, earliest;
- int compare_and_branch;
-
- /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
- since BLOCK_REG[BB] is zero if this block did not end with a
- comparison against zero, this condition works. */
- if (block_reg[bb->index] < npi->min_reg
- || block_reg[bb->index] >= npi->max_reg)
- continue;
-
- /* LAST_INSN is a conditional jump. Get its condition. */
- condition = get_condition (last_insn, &earliest);
-
- /* If we can't determine the condition then skip. */
- if (! condition)
- continue;
-
- /* Is the register known to have a nonzero value? */
- if (!TEST_BIT (nonnull_avout[bb->index], block_reg[bb->index] - npi->min_reg))
- continue;
+ struct ls_expr * tmp = pre_ldst_mems;
- /* Try to compute whether the compare/branch at the loop end is one or
- two instructions. */
- if (earliest == last_insn)
- compare_and_branch = 1;
- else if (earliest == prev_nonnote_insn (last_insn))
- compare_and_branch = 2;
- else
- continue;
+ pre_ldst_mems = pre_ldst_mems->next;
- /* We know the register in this comparison is nonnull at exit from
- this block. We can optimize this comparison. */
- if (GET_CODE (condition) == NE)
- {
- rtx new_jump;
+ free_ldst_entry (tmp);
+ }
- new_jump = emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn)),
- last_insn);
- JUMP_LABEL (new_jump) = JUMP_LABEL (last_insn);
- LABEL_NUSES (JUMP_LABEL (new_jump))++;
- emit_barrier_after (new_jump);
- }
+ pre_ldst_mems = NULL;
+}
- something_changed = 1;
- delete_insn (last_insn);
- if (compare_and_branch == 2)
- delete_insn (earliest);
- purge_dead_edges (bb);
+/* Dump debugging info about the ldst list. */
- /* Don't check this block again. (Note that BLOCK_END is
- invalid here; we deleted the last instruction in the
- block.) */
- block_reg[bb->index] = 0;
- }
+static void
+print_ldst_list (FILE * file)
+{
+ struct ls_expr * ptr;
- return something_changed;
-}
+ fprintf (file, "LDST list: \n");
-/* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
- at compile time.
+ for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
+ {
+ fprintf (file, " Pattern (%3d): ", ptr->index);
- This is conceptually similar to global constant/copy propagation and
- classic global CSE (it even uses the same dataflow equations as cprop).
+ print_rtl (file, ptr->pattern);
- If a register is used as memory address with the form (mem (reg)), then we
- know that REG can not be zero at that point in the program. Any instruction
- which sets REG "kills" this property.
+ fprintf (file, "\n Loads : ");
- So, if every path leading to a conditional branch has an available memory
- reference of that form, then we know the register can not have the value
- zero at the conditional branch.
+ if (ptr->loads)
+ print_rtl (file, ptr->loads);
+ else
+ fprintf (file, "(nil)");
- So we merely need to compute the local properties and propagate that data
- around the cfg, then optimize where possible.
+ fprintf (file, "\n Stores : ");
- We run this pass two times. Once before CSE, then again after CSE. This
- has proven to be the most profitable approach. It is rare for new
- optimization opportunities of this nature to appear after the first CSE
- pass.
+ if (ptr->stores)
+ print_rtl (file, ptr->stores);
+ else
+ fprintf (file, "(nil)");
- This could probably be integrated with global cprop with a little work. */
+ fprintf (file, "\n\n");
+ }
-int
-delete_null_pointer_checks (f)
- rtx f ATTRIBUTE_UNUSED;
-{
- sbitmap *nonnull_avin, *nonnull_avout;
- unsigned int *block_reg;
- basic_block bb;
- int reg;
- int regs_per_pass;
- int max_reg;
- struct null_pointer_info npi;
- int something_changed = 0;
-
- /* If we have only a single block, then there's nothing to do. */
- if (n_basic_blocks <= 1)
- return 0;
+ fprintf (file, "\n");
+}
- /* Trying to perform global optimizations on flow graphs which have
- a high connectivity will take a long time and is unlikely to be
- particularly useful.
+/* Returns 1 if X is in the list of ldst only expressions. */
- In normal circumstances a cfg should have about twice as many edges
- as blocks. But we do not want to punish small functions which have
- a couple switch statements. So we require a relatively large number
- of basic blocks and the ratio of edges to blocks to be high. */
- if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
- return 0;
+static struct ls_expr *
+find_rtx_in_ldst (rtx x)
+{
+ struct ls_expr * ptr;
- /* We need four bitmaps, each with a bit for each register in each
- basic block. */
- max_reg = max_reg_num ();
- regs_per_pass = get_bitmap_width (4, last_basic_block, max_reg);
-
- /* Allocate bitmaps to hold local and global properties. */
- npi.nonnull_local = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
- npi.nonnull_killed = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
- nonnull_avin = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
- nonnull_avout = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
-
- /* Go through the basic blocks, seeing whether or not each block
- ends with a conditional branch whose condition is a comparison
- against zero. Record the register compared in BLOCK_REG. */
- block_reg = (unsigned int *) xcalloc (last_basic_block, sizeof (int));
- FOR_EACH_BB (bb)
- {
- rtx last_insn = bb->end;
- rtx condition, earliest, reg;
+ for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
+ if (expr_equiv_p (ptr->pattern, x) && ! ptr->invalid)
+ return ptr;
- /* We only want conditional branches. */
- if (GET_CODE (last_insn) != JUMP_INSN
- || !any_condjump_p (last_insn)
- || !onlyjump_p (last_insn))
- continue;
+ return NULL;
+}
- /* LAST_INSN is a conditional jump. Get its condition. */
- condition = get_condition (last_insn, &earliest);
+/* Assign each element of the list of mems a monotonically increasing value. */
- /* If we were unable to get the condition, or it is not an equality
- comparison against zero then there's nothing we can do. */
- if (!condition
- || (GET_CODE (condition) != NE && GET_CODE (condition) != EQ)
- || GET_CODE (XEXP (condition, 1)) != CONST_INT
- || (XEXP (condition, 1)
- != CONST0_RTX (GET_MODE (XEXP (condition, 0)))))
- continue;
+static int
+enumerate_ldsts (void)
+{
+ struct ls_expr * ptr;
+ int n = 0;
- /* We must be checking a register against zero. */
- reg = XEXP (condition, 0);
- if (GET_CODE (reg) != REG)
- continue;
+ for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
+ ptr->index = n++;
- block_reg[bb->index] = REGNO (reg);
- }
+ return n;
+}
- /* Go through the algorithm for each block of registers. */
- for (reg = FIRST_PSEUDO_REGISTER; reg < max_reg; reg += regs_per_pass)
- {
- npi.min_reg = reg;
- npi.max_reg = MIN (reg + regs_per_pass, max_reg);
- something_changed |= delete_null_pointer_checks_1 (block_reg,
- nonnull_avin,
- nonnull_avout,
- &npi);
- }
+/* Return first item in the list. */
- /* Free the table of registers compared at the end of every block. */
- free (block_reg);
+static inline struct ls_expr *
+first_ls_expr (void)
+{
+ return pre_ldst_mems;
+}
- /* Free bitmaps. */
- sbitmap_vector_free (npi.nonnull_local);
- sbitmap_vector_free (npi.nonnull_killed);
- sbitmap_vector_free (nonnull_avin);
- sbitmap_vector_free (nonnull_avout);
+/* Return the next item in the list after the specified one. */
- return something_changed;
+static inline struct ls_expr *
+next_ls_expr (struct ls_expr * ptr)
+{
+ return ptr->next;
}
+\f
+/* Load Motion for loads which only kill themselves. */
-/* Code Hoisting variables and subroutines. */
+/* Return true if x is a simple MEM operation, with no registers or
+ side effects. These are the types of loads we consider for the
+ ld_motion list, otherwise we let the usual aliasing take care of it. */
-/* Very busy expressions. */
-static sbitmap *hoist_vbein;
-static sbitmap *hoist_vbeout;
+static int
+simple_mem (rtx x)
+{
+ if (! MEM_P (x))
+ return 0;
-/* Hoistable expressions. */
-static sbitmap *hoist_exprs;
+ if (MEM_VOLATILE_P (x))
+ return 0;
-/* Dominator bitmaps. */
-dominance_info dominators;
+ if (GET_MODE (x) == BLKmode)
+ return 0;
-/* ??? We could compute post dominators and run this algorithm in
- reverse to perform tail merging, doing so would probably be
- more effective than the tail merging code in jump.c.
+ /* If we are handling exceptions, we must be careful with memory references
+ that may trap. If we are not, the behavior is undefined, so we may just
+ continue. */
+ if (flag_non_call_exceptions && may_trap_p (x))
+ return 0;
- It's unclear if tail merging could be run in parallel with
- code hoisting. It would be nice. */
+ if (side_effects_p (x))
+ return 0;
-/* Allocate vars used for code hoisting analysis. */
+ /* Do not consider function arguments passed on stack. */
+ if (reg_mentioned_p (stack_pointer_rtx, x))
+ return 0;
-static void
-alloc_code_hoist_mem (n_blocks, n_exprs)
- int n_blocks, n_exprs;
-{
- antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
- transp = sbitmap_vector_alloc (n_blocks, n_exprs);
- comp = sbitmap_vector_alloc (n_blocks, n_exprs);
+ if (flag_float_store && FLOAT_MODE_P (GET_MODE (x)))
+ return 0;
- hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
- hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
- hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
- transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
+ return 1;
}
-/* Free vars used for code hoisting analysis. */
+/* Make sure there isn't a buried reference in this pattern anywhere.
+ If there is, invalidate the entry for it since we're not capable
+ of fixing it up just yet.. We have to be sure we know about ALL
+ loads since the aliasing code will allow all entries in the
+ ld_motion list to not-alias itself. If we miss a load, we will get
+ the wrong value since gcse might common it and we won't know to
+ fix it up. */
static void
-free_code_hoist_mem ()
+invalidate_any_buried_refs (rtx x)
{
- sbitmap_vector_free (antloc);
- sbitmap_vector_free (transp);
- sbitmap_vector_free (comp);
+ const char * fmt;
+ int i, j;
+ struct ls_expr * ptr;
- sbitmap_vector_free (hoist_vbein);
- sbitmap_vector_free (hoist_vbeout);
- sbitmap_vector_free (hoist_exprs);
- sbitmap_vector_free (transpout);
+ /* Invalidate it in the list. */
+ if (MEM_P (x) && simple_mem (x))
+ {
+ ptr = ldst_entry (x);
+ ptr->invalid = 1;
+ }
- free_dominance_info (dominators);
-}
+ /* Recursively process the insn. */
+ fmt = GET_RTX_FORMAT (GET_CODE (x));
-/* Compute the very busy expressions at entry/exit from each block.
+ for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
+ {
+ if (fmt[i] == 'e')
+ invalidate_any_buried_refs (XEXP (x, i));
+ else if (fmt[i] == 'E')
+ for (j = XVECLEN (x, i) - 1; j >= 0; j--)
+ invalidate_any_buried_refs (XVECEXP (x, i, j));
+ }
+}
- An expression is very busy if all paths from a given point
- compute the expression. */
+/* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
+ being defined as MEM loads and stores to symbols, with no side effects
+ and no registers in the expression. For a MEM destination, we also
+ check that the insn is still valid if we replace the destination with a
+ REG, as is done in update_ld_motion_stores. If there are any uses/defs
+ which don't match this criteria, they are invalidated and trimmed out
+ later. */
static void
-compute_code_hoist_vbeinout ()
+compute_ld_motion_mems (void)
{
- int changed, passes;
+ struct ls_expr * ptr;
basic_block bb;
+ rtx insn;
- sbitmap_vector_zero (hoist_vbeout, last_basic_block);
- sbitmap_vector_zero (hoist_vbein, last_basic_block);
-
- passes = 0;
- changed = 1;
+ pre_ldst_mems = NULL;
- while (changed)
+ FOR_EACH_BB (bb)
{
- changed = 0;
-
- /* We scan the blocks in the reverse order to speed up
- the convergence. */
- FOR_EACH_BB_REVERSE (bb)
+ for (insn = BB_HEAD (bb);
+ insn && insn != NEXT_INSN (BB_END (bb));
+ insn = NEXT_INSN (insn))
{
- changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index],
- hoist_vbeout[bb->index], transp[bb->index]);
- if (bb->next_bb != EXIT_BLOCK_PTR)
- sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index);
- }
-
- passes++;
- }
+ if (INSN_P (insn))
+ {
+ if (GET_CODE (PATTERN (insn)) == SET)
+ {
+ rtx src = SET_SRC (PATTERN (insn));
+ rtx dest = SET_DEST (PATTERN (insn));
- if (gcse_file)
- fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes);
-}
+ /* Check for a simple LOAD... */
+ if (MEM_P (src) && simple_mem (src))
+ {
+ ptr = ldst_entry (src);
+ if (REG_P (dest))
+ ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
+ else
+ ptr->invalid = 1;
+ }
+ else
+ {
+ /* Make sure there isn't a buried load somewhere. */
+ invalidate_any_buried_refs (src);
+ }
-/* Top level routine to do the dataflow analysis needed by code hoisting. */
+ /* Check for stores. Don't worry about aliased ones, they
+ will block any movement we might do later. We only care
+ about this exact pattern since those are the only
+ circumstance that we will ignore the aliasing info. */
+ if (MEM_P (dest) && simple_mem (dest))
+ {
+ ptr = ldst_entry (dest);
-static void
-compute_code_hoist_data ()
-{
- compute_local_properties (transp, comp, antloc, &expr_hash_table);
- compute_transpout ();
- compute_code_hoist_vbeinout ();
- dominators = calculate_dominance_info (CDI_DOMINATORS);
- if (gcse_file)
- fprintf (gcse_file, "\n");
+ if (! MEM_P (src)
+ && GET_CODE (src) != ASM_OPERANDS
+ /* Check for REG manually since want_to_gcse_p
+ returns 0 for all REGs. */
+ && can_assign_to_reg_p (src))
+ ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
+ else
+ ptr->invalid = 1;
+ }
+ }
+ else
+ invalidate_any_buried_refs (PATTERN (insn));
+ }
+ }
+ }
}
-/* Determine if the expression identified by EXPR_INDEX would
- reach BB unimpared if it was placed at the end of EXPR_BB.
-
- It's unclear exactly what Muchnick meant by "unimpared". It seems
- to me that the expression must either be computed or transparent in
- *every* block in the path(s) from EXPR_BB to BB. Any other definition
- would allow the expression to be hoisted out of loops, even if
- the expression wasn't a loop invariant.
-
- Contrast this to reachability for PRE where an expression is
- considered reachable if *any* path reaches instead of *all*
- paths. */
+/* Remove any references that have been either invalidated or are not in the
+ expression list for pre gcse. */
-static int
-hoist_expr_reaches_here_p (expr_bb, expr_index, bb, visited)
- basic_block expr_bb;
- int expr_index;
- basic_block bb;
- char *visited;
+static void
+trim_ld_motion_mems (void)
{
- edge pred;
- int visited_allocated_locally = 0;
-
-
- if (visited == NULL)
- {
- visited_allocated_locally = 1;
- visited = xcalloc (last_basic_block, 1);
- }
+ struct ls_expr * * last = & pre_ldst_mems;
+ struct ls_expr * ptr = pre_ldst_mems;
- for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
+ while (ptr != NULL)
{
- basic_block pred_bb = pred->src;
+ struct expr * expr;
- if (pred->src == ENTRY_BLOCK_PTR)
- break;
- else if (pred_bb == expr_bb)
- continue;
- else if (visited[pred_bb->index])
- continue;
+ /* Delete if entry has been made invalid. */
+ if (! ptr->invalid)
+ {
+ /* Delete if we cannot find this mem in the expression list. */
+ unsigned int hash = ptr->hash_index % expr_hash_table.size;
- /* Does this predecessor generate this expression? */
- else if (TEST_BIT (comp[pred_bb->index], expr_index))
- break;
- else if (! TEST_BIT (transp[pred_bb->index], expr_index))
- break;
+ for (expr = expr_hash_table.table[hash];
+ expr != NULL;
+ expr = expr->next_same_hash)
+ if (expr_equiv_p (expr->expr, ptr->pattern))
+ break;
+ }
+ else
+ expr = (struct expr *) 0;
- /* Not killed. */
+ if (expr)
+ {
+ /* Set the expression field if we are keeping it. */
+ ptr->expr = expr;
+ last = & ptr->next;
+ ptr = ptr->next;
+ }
else
{
- visited[pred_bb->index] = 1;
- if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
- pred_bb, visited))
- break;
+ *last = ptr->next;
+ free_ldst_entry (ptr);
+ ptr = * last;
}
}
- if (visited_allocated_locally)
- free (visited);
- return (pred == NULL);
+ /* Show the world what we've found. */
+ if (gcse_file && pre_ldst_mems != NULL)
+ print_ldst_list (gcse_file);
}
-\f
-/* Actually perform code hoisting. */
+
+/* This routine will take an expression which we are replacing with
+ a reaching register, and update any stores that are needed if
+ that expression is in the ld_motion list. Stores are updated by
+ copying their SRC to the reaching register, and then storing
+ the reaching register into the store location. These keeps the
+ correct value in the reaching register for the loads. */
static void
-hoist_code ()
+update_ld_motion_stores (struct expr * expr)
{
- basic_block bb, dominated;
- basic_block *domby;
- unsigned int domby_len;
- unsigned int i,j;
- struct expr **index_map;
- struct expr *expr;
-
- sbitmap_vector_zero (hoist_exprs, last_basic_block);
-
- /* Compute a mapping from expression number (`bitmap_index') to
- hash table entry. */
-
- index_map = (struct expr **) xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
- for (i = 0; i < expr_hash_table.size; i++)
- for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
- index_map[expr->bitmap_index] = expr;
+ struct ls_expr * mem_ptr;
- /* Walk over each basic block looking for potentially hoistable
- expressions, nothing gets hoisted from the entry block. */
- FOR_EACH_BB (bb)
+ if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
{
- int found = 0;
- int insn_inserted_p;
+ /* We can try to find just the REACHED stores, but is shouldn't
+ matter to set the reaching reg everywhere... some might be
+ dead and should be eliminated later. */
- domby_len = get_dominated_by (dominators, bb, &domby);
- /* Examine each expression that is very busy at the exit of this
- block. These are the potentially hoistable expressions. */
- for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
+ /* We replace (set mem expr) with (set reg expr) (set mem reg)
+ where reg is the reaching reg used in the load. We checked in
+ compute_ld_motion_mems that we can replace (set mem expr) with
+ (set reg expr) in that insn. */
+ rtx list = mem_ptr->stores;
+
+ for ( ; list != NULL_RTX; list = XEXP (list, 1))
{
- int hoistable = 0;
+ rtx insn = XEXP (list, 0);
+ rtx pat = PATTERN (insn);
+ rtx src = SET_SRC (pat);
+ rtx reg = expr->reaching_reg;
+ rtx copy, new;
- if (TEST_BIT (hoist_vbeout[bb->index], i)
- && TEST_BIT (transpout[bb->index], i))
- {
- /* We've found a potentially hoistable expression, now
- we look at every block BB dominates to see if it
- computes the expression. */
- for (j = 0; j < domby_len; j++)
- {
- dominated = domby[j];
- /* Ignore self dominance. */
- if (bb == dominated)
- continue;
- /* We've found a dominated block, now see if it computes
- the busy expression and whether or not moving that
- expression to the "beginning" of that block is safe. */
- if (!TEST_BIT (antloc[dominated->index], i))
- continue;
+ /* If we've already copied it, continue. */
+ if (expr->reaching_reg == src)
+ continue;
- /* Note if the expression would reach the dominated block
- unimpared if it was placed at the end of BB.
+ if (gcse_file)
+ {
+ fprintf (gcse_file, "PRE: store updated with reaching reg ");
+ print_rtl (gcse_file, expr->reaching_reg);
+ fprintf (gcse_file, ":\n ");
+ print_inline_rtx (gcse_file, insn, 8);
+ fprintf (gcse_file, "\n");
+ }
- Keep track of how many times this expression is hoistable
- from a dominated block into BB. */
- if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
- hoistable++;
- }
+ copy = gen_move_insn ( reg, copy_rtx (SET_SRC (pat)));
+ new = emit_insn_before (copy, insn);
+ record_one_set (REGNO (reg), new);
+ SET_SRC (pat) = reg;
- /* If we found more than one hoistable occurrence of this
- expression, then note it in the bitmap of expressions to
- hoist. It makes no sense to hoist things which are computed
- in only one BB, and doing so tends to pessimize register
- allocation. One could increase this value to try harder
- to avoid any possible code expansion due to register
- allocation issues; however experiments have shown that
- the vast majority of hoistable expressions are only movable
- from two successors, so raising this threshhold is likely
- to nullify any benefit we get from code hoisting. */
- if (hoistable > 1)
- {
- SET_BIT (hoist_exprs[bb->index], i);
- found = 1;
- }
- }
- }
- /* If we found nothing to hoist, then quit now. */
- if (! found)
- {
- free (domby);
- continue;
+ /* un-recognize this pattern since it's probably different now. */
+ INSN_CODE (insn) = -1;
+ gcse_create_count++;
}
+ }
+}
+\f
+/* Store motion code. */
- /* Loop over all the hoistable expressions. */
- for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
- {
- /* We want to insert the expression into BB only once, so
- note when we've inserted it. */
- insn_inserted_p = 0;
-
- /* These tests should be the same as the tests above. */
- if (TEST_BIT (hoist_vbeout[bb->index], i))
- {
- /* We've found a potentially hoistable expression, now
- we look at every block BB dominates to see if it
- computes the expression. */
- for (j = 0; j < domby_len; j++)
- {
- dominated = domby[j];
- /* Ignore self dominance. */
- if (bb == dominated)
- continue;
+#define ANTIC_STORE_LIST(x) ((x)->loads)
+#define AVAIL_STORE_LIST(x) ((x)->stores)
+#define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
- /* We've found a dominated block, now see if it computes
- the busy expression and whether or not moving that
- expression to the "beginning" of that block is safe. */
- if (!TEST_BIT (antloc[dominated->index], i))
- continue;
+/* This is used to communicate the target bitvector we want to use in the
+ reg_set_info routine when called via the note_stores mechanism. */
+static int * regvec;
- /* The expression is computed in the dominated block and
- it would be safe to compute it at the start of the
- dominated block. Now we have to determine if the
- expression would reach the dominated block if it was
- placed at the end of BB. */
- if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
- {
- struct expr *expr = index_map[i];
- struct occr *occr = expr->antic_occr;
- rtx insn;
- rtx set;
+/* And current insn, for the same routine. */
+static rtx compute_store_table_current_insn;
- /* Find the right occurrence of this expression. */
- while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
- occr = occr->next;
+/* Used in computing the reverse edge graph bit vectors. */
+static sbitmap * st_antloc;
- /* Should never happen. */
- if (!occr)
- abort ();
+/* Global holding the number of store expressions we are dealing with. */
+static int num_stores;
- insn = occr->insn;
+/* Checks to set if we need to mark a register set. Called from
+ note_stores. */
- set = single_set (insn);
- if (! set)
- abort ();
+static void
+reg_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED,
+ void *data)
+{
+ sbitmap bb_reg = data;
- /* Create a pseudo-reg to store the result of reaching
- expressions into. Get the mode for the new pseudo
- from the mode of the original destination pseudo. */
- if (expr->reaching_reg == NULL)
- expr->reaching_reg
- = gen_reg_rtx (GET_MODE (SET_DEST (set)));
+ if (GET_CODE (dest) == SUBREG)
+ dest = SUBREG_REG (dest);
- gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
- delete_insn (insn);
- occr->deleted_p = 1;
- if (!insn_inserted_p)
- {
- insert_insn_end_bb (index_map[i], bb, 0);
- insn_inserted_p = 1;
- }
- }
- }
- }
- }
- free (domby);
+ if (REG_P (dest))
+ {
+ regvec[REGNO (dest)] = INSN_UID (compute_store_table_current_insn);
+ if (bb_reg)
+ SET_BIT (bb_reg, REGNO (dest));
}
-
- free (index_map);
}
-/* Top level routine to perform one code hoisting (aka unification) pass
-
- Return nonzero if a change was made. */
+/* Clear any mark that says that this insn sets dest. Called from
+ note_stores. */
-static int
-one_code_hoisting_pass ()
+static void
+reg_clear_last_set (rtx dest, rtx setter ATTRIBUTE_UNUSED,
+ void *data)
{
- int changed = 0;
-
- alloc_hash_table (max_cuid, &expr_hash_table, 0);
- compute_hash_table (&expr_hash_table);
- if (gcse_file)
- dump_hash_table (gcse_file, "Code Hosting Expressions", &expr_hash_table);
-
- if (expr_hash_table.n_elems > 0)
- {
- alloc_code_hoist_mem (last_basic_block, expr_hash_table.n_elems);
- compute_code_hoist_data ();
- hoist_code ();
- free_code_hoist_mem ();
- }
+ int *dead_vec = data;
- free_hash_table (&expr_hash_table);
+ if (GET_CODE (dest) == SUBREG)
+ dest = SUBREG_REG (dest);
- return changed;
+ if (REG_P (dest) &&
+ dead_vec[REGNO (dest)] == INSN_UID (compute_store_table_current_insn))
+ dead_vec[REGNO (dest)] = 0;
}
-\f
-/* Here we provide the things required to do store motion towards
- the exit. In order for this to be effective, gcse also needed to
- be taught how to move a load when it is kill only by a store to itself.
-
- int i;
- float a[10];
- void foo(float scale)
- {
- for (i=0; i<10; i++)
- a[i] *= scale;
- }
+/* Return zero if some of the registers in list X are killed
+ due to set of registers in bitmap REGS_SET. */
- 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
- the load out since its live around the loop, and stored at the bottom
- of the loop.
+static bool
+store_ops_ok (rtx x, int *regs_set)
+{
+ rtx reg;
- The 'Load Motion' referred to and implemented in this file is
- an enhancement to gcse which when using edge based lcm, recognizes
- this situation and allows gcse to move the load out of the loop.
+ for (; x; x = XEXP (x, 1))
+ {
+ reg = XEXP (x, 0);
+ if (regs_set[REGNO(reg)])
+ return false;
+ }
- Once gcse has hoisted the load, store motion can then push this
- load towards the exit, and we end up with no loads or stores of 'i'
- in the loop. */
+ return true;
+}
-/* This will search the ldst list for a matching expression. If it
- doesn't find one, we create one and initialize it. */
+/* Returns a list of registers mentioned in X. */
+static rtx
+extract_mentioned_regs (rtx x)
+{
+ return extract_mentioned_regs_helper (x, NULL_RTX);
+}
-static struct ls_expr *
-ldst_entry (x)
- rtx x;
+/* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
+ registers. */
+static rtx
+extract_mentioned_regs_helper (rtx x, rtx accum)
{
- struct ls_expr * ptr;
+ int i;
+ enum rtx_code code;
+ const char * fmt;
- for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
- if (expr_equiv_p (ptr->pattern, x))
- break;
+ /* Repeat is used to turn tail-recursion into iteration. */
+ repeat:
- if (!ptr)
- {
- ptr = (struct ls_expr *) xmalloc (sizeof (struct ls_expr));
+ if (x == 0)
+ return accum;
- ptr->next = pre_ldst_mems;
- ptr->expr = NULL;
- ptr->pattern = x;
- ptr->loads = NULL_RTX;
- ptr->stores = NULL_RTX;
- ptr->reaching_reg = NULL_RTX;
- ptr->invalid = 0;
- ptr->index = 0;
- ptr->hash_index = 0;
- pre_ldst_mems = ptr;
- }
+ code = GET_CODE (x);
+ switch (code)
+ {
+ case REG:
+ return alloc_EXPR_LIST (0, x, accum);
- return ptr;
-}
+ case MEM:
+ x = XEXP (x, 0);
+ goto repeat;
-/* Free up an individual ldst entry. */
+ case PRE_DEC:
+ case PRE_INC:
+ case POST_DEC:
+ case POST_INC:
+ /* We do not run this function with arguments having side effects. */
+ abort ();
-static void
-free_ldst_entry (ptr)
- struct ls_expr * ptr;
-{
- free_INSN_LIST_list (& ptr->loads);
- free_INSN_LIST_list (& ptr->stores);
+ case PC:
+ case CC0: /*FIXME*/
+ case CONST:
+ case CONST_INT:
+ case CONST_DOUBLE:
+ case CONST_VECTOR:
+ case SYMBOL_REF:
+ case LABEL_REF:
+ case ADDR_VEC:
+ case ADDR_DIFF_VEC:
+ return accum;
- free (ptr);
-}
+ default:
+ break;
+ }
-/* Free up all memory associated with the ldst list. */
+ i = GET_RTX_LENGTH (code) - 1;
+ fmt = GET_RTX_FORMAT (code);
-static void
-free_ldst_mems ()
-{
- while (pre_ldst_mems)
+ for (; i >= 0; i--)
{
- struct ls_expr * tmp = pre_ldst_mems;
+ if (fmt[i] == 'e')
+ {
+ rtx tem = XEXP (x, i);
- pre_ldst_mems = pre_ldst_mems->next;
+ /* If we are about to do the last recursive call
+ needed at this level, change it into iteration. */
+ if (i == 0)
+ {
+ x = tem;
+ goto repeat;
+ }
- free_ldst_entry (tmp);
+ accum = extract_mentioned_regs_helper (tem, accum);
+ }
+ else if (fmt[i] == 'E')
+ {
+ int j;
+
+ for (j = 0; j < XVECLEN (x, i); j++)
+ accum = extract_mentioned_regs_helper (XVECEXP (x, i, j), accum);
+ }
}
- pre_ldst_mems = NULL;
+ return accum;
}
-/* Dump debugging info about the ldst list. */
+/* Determine whether INSN is MEM store pattern that we will consider moving.
+ REGS_SET_BEFORE is bitmap of registers set before (and including) the
+ current insn, REGS_SET_AFTER is bitmap of registers set after (and
+ including) the insn in this basic block. We must be passing through BB from
+ head to end, as we are using this fact to speed things up.
+
+ The results are stored this way:
+
+ -- the first anticipatable expression is added into ANTIC_STORE_LIST
+ -- if the processed expression is not anticipatable, NULL_RTX is added
+ there instead, so that we can use it as indicator that no further
+ expression of this type may be anticipatable
+ -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
+ consequently, all of them but this head are dead and may be deleted.
+ -- if the expression is not available, the insn due to that it fails to be
+ available is stored in reaching_reg.
+
+ The things are complicated a bit by fact that there already may be stores
+ to the same MEM from other blocks; also caller must take care of the
+ necessary cleanup of the temporary markers after end of the basic block.
+ */
static void
-print_ldst_list (file)
- FILE * file;
+find_moveable_store (rtx insn, int *regs_set_before, int *regs_set_after)
{
struct ls_expr * ptr;
+ rtx dest, set, tmp;
+ int check_anticipatable, check_available;
+ basic_block bb = BLOCK_FOR_INSN (insn);
- fprintf (file, "LDST list: \n");
+ set = single_set (insn);
+ if (!set)
+ return;
- for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
- {
- fprintf (file, " Pattern (%3d): ", ptr->index);
+ dest = SET_DEST (set);
- print_rtl (file, ptr->pattern);
+ if (! MEM_P (dest) || MEM_VOLATILE_P (dest)
+ || GET_MODE (dest) == BLKmode)
+ return;
- fprintf (file, "\n Loads : ");
+ if (side_effects_p (dest))
+ return;
- if (ptr->loads)
- print_rtl (file, ptr->loads);
- else
- fprintf (file, "(nil)");
+ /* If we are handling exceptions, we must be careful with memory references
+ that may trap. If we are not, the behavior is undefined, so we may just
+ continue. */
+ if (flag_non_call_exceptions && may_trap_p (dest))
+ return;
- fprintf (file, "\n Stores : ");
+ /* Even if the destination cannot trap, the source may. In this case we'd
+ need to handle updating the REG_EH_REGION note. */
+ if (find_reg_note (insn, REG_EH_REGION, NULL_RTX))
+ return;
- if (ptr->stores)
- print_rtl (file, ptr->stores);
+ ptr = ldst_entry (dest);
+ if (!ptr->pattern_regs)
+ ptr->pattern_regs = extract_mentioned_regs (dest);
+
+ /* Do not check for anticipatability if we either found one anticipatable
+ store already, or tested for one and found out that it was killed. */
+ check_anticipatable = 0;
+ if (!ANTIC_STORE_LIST (ptr))
+ check_anticipatable = 1;
+ else
+ {
+ tmp = XEXP (ANTIC_STORE_LIST (ptr), 0);
+ if (tmp != NULL_RTX
+ && BLOCK_FOR_INSN (tmp) != bb)
+ check_anticipatable = 1;
+ }
+ if (check_anticipatable)
+ {
+ if (store_killed_before (dest, ptr->pattern_regs, insn, bb, regs_set_before))
+ tmp = NULL_RTX;
else
- fprintf (file, "(nil)");
-
- fprintf (file, "\n\n");
+ tmp = insn;
+ ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (tmp,
+ ANTIC_STORE_LIST (ptr));
}
- fprintf (file, "\n");
+ /* It is not necessary to check whether store is available if we did
+ it successfully before; if we failed before, do not bother to check
+ until we reach the insn that caused us to fail. */
+ check_available = 0;
+ if (!AVAIL_STORE_LIST (ptr))
+ check_available = 1;
+ else
+ {
+ tmp = XEXP (AVAIL_STORE_LIST (ptr), 0);
+ if (BLOCK_FOR_INSN (tmp) != bb)
+ check_available = 1;
+ }
+ if (check_available)
+ {
+ /* Check that we have already reached the insn at that the check
+ failed last time. */
+ if (LAST_AVAIL_CHECK_FAILURE (ptr))
+ {
+ for (tmp = BB_END (bb);
+ tmp != insn && tmp != LAST_AVAIL_CHECK_FAILURE (ptr);
+ tmp = PREV_INSN (tmp))
+ continue;
+ if (tmp == insn)
+ check_available = 0;
+ }
+ else
+ check_available = store_killed_after (dest, ptr->pattern_regs, insn,
+ bb, regs_set_after,
+ &LAST_AVAIL_CHECK_FAILURE (ptr));
+ }
+ if (!check_available)
+ AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn, AVAIL_STORE_LIST (ptr));
}
-/* Returns 1 if X is in the list of ldst only expressions. */
+/* Find available and anticipatable stores. */
-static struct ls_expr *
-find_rtx_in_ldst (x)
- rtx x;
+static int
+compute_store_table (void)
{
- struct ls_expr * ptr;
+ int ret;
+ basic_block bb;
+ unsigned regno;
+ rtx insn, pat, tmp;
+ int *last_set_in, *already_set;
+ struct ls_expr * ptr, **prev_next_ptr_ptr;
- for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
- if (expr_equiv_p (ptr->pattern, x) && ! ptr->invalid)
- return ptr;
+ max_gcse_regno = max_reg_num ();
- return NULL;
-}
+ reg_set_in_block = sbitmap_vector_alloc (last_basic_block,
+ max_gcse_regno);
+ sbitmap_vector_zero (reg_set_in_block, last_basic_block);
+ pre_ldst_mems = 0;
+ last_set_in = xcalloc (max_gcse_regno, sizeof (int));
+ already_set = xmalloc (sizeof (int) * max_gcse_regno);
-/* Assign each element of the list of mems a monotonically increasing value. */
+ /* Find all the stores we care about. */
+ FOR_EACH_BB (bb)
+ {
+ /* First compute the registers set in this block. */
+ regvec = last_set_in;
-static int
-enumerate_ldsts ()
-{
- struct ls_expr * ptr;
- int n = 0;
+ for (insn = BB_HEAD (bb);
+ insn != NEXT_INSN (BB_END (bb));
+ insn = NEXT_INSN (insn))
+ {
+ if (! INSN_P (insn))
+ continue;
- for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
- ptr->index = n++;
+ if (CALL_P (insn))
+ {
+ bool clobbers_all = false;
+#ifdef NON_SAVING_SETJMP
+ if (NON_SAVING_SETJMP
+ && find_reg_note (insn, REG_SETJMP, NULL_RTX))
+ clobbers_all = true;
+#endif
- return n;
-}
+ for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
+ if (clobbers_all
+ || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
+ {
+ last_set_in[regno] = INSN_UID (insn);
+ SET_BIT (reg_set_in_block[bb->index], regno);
+ }
+ }
-/* Return first item in the list. */
+ pat = PATTERN (insn);
+ compute_store_table_current_insn = insn;
+ note_stores (pat, reg_set_info, reg_set_in_block[bb->index]);
+ }
-static inline struct ls_expr *
-first_ls_expr ()
-{
- return pre_ldst_mems;
-}
+ /* Now find the stores. */
+ memset (already_set, 0, sizeof (int) * max_gcse_regno);
+ regvec = already_set;
+ for (insn = BB_HEAD (bb);
+ insn != NEXT_INSN (BB_END (bb));
+ insn = NEXT_INSN (insn))
+ {
+ if (! INSN_P (insn))
+ continue;
-/* Return the next item in ther list after the specified one. */
+ if (CALL_P (insn))
+ {
+ bool clobbers_all = false;
+#ifdef NON_SAVING_SETJMP
+ if (NON_SAVING_SETJMP
+ && find_reg_note (insn, REG_SETJMP, NULL_RTX))
+ clobbers_all = true;
+#endif
-static inline struct ls_expr *
-next_ls_expr (ptr)
- struct ls_expr * ptr;
-{
- return ptr->next;
-}
-\f
-/* Load Motion for loads which only kill themselves. */
+ for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
+ if (clobbers_all
+ || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
+ already_set[regno] = 1;
+ }
-/* Return true if x is a simple MEM operation, with no registers or
- side effects. These are the types of loads we consider for the
- ld_motion list, otherwise we let the usual aliasing take care of it. */
+ pat = PATTERN (insn);
+ note_stores (pat, reg_set_info, NULL);
-static int
-simple_mem (x)
- rtx x;
-{
- if (GET_CODE (x) != MEM)
- return 0;
+ /* Now that we've marked regs, look for stores. */
+ find_moveable_store (insn, already_set, last_set_in);
- if (MEM_VOLATILE_P (x))
- return 0;
+ /* Unmark regs that are no longer set. */
+ compute_store_table_current_insn = insn;
+ note_stores (pat, reg_clear_last_set, last_set_in);
+ if (CALL_P (insn))
+ {
+ bool clobbers_all = false;
+#ifdef NON_SAVING_SETJMP
+ if (NON_SAVING_SETJMP
+ && find_reg_note (insn, REG_SETJMP, NULL_RTX))
+ clobbers_all = true;
+#endif
- if (GET_MODE (x) == BLKmode)
- return 0;
+ for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
+ if ((clobbers_all
+ || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
+ && last_set_in[regno] == INSN_UID (insn))
+ last_set_in[regno] = 0;
+ }
+ }
- if (!rtx_varies_p (XEXP (x, 0), 0))
- return 1;
+#ifdef ENABLE_CHECKING
+ /* last_set_in should now be all-zero. */
+ for (regno = 0; regno < max_gcse_regno; regno++)
+ if (last_set_in[regno] != 0)
+ abort ();
+#endif
- return 0;
+ /* Clear temporary marks. */
+ for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
+ {
+ LAST_AVAIL_CHECK_FAILURE(ptr) = NULL_RTX;
+ if (ANTIC_STORE_LIST (ptr)
+ && (tmp = XEXP (ANTIC_STORE_LIST (ptr), 0)) == NULL_RTX)
+ ANTIC_STORE_LIST (ptr) = XEXP (ANTIC_STORE_LIST (ptr), 1);
+ }
+ }
+
+ /* Remove the stores that are not available anywhere, as there will
+ be no opportunity to optimize them. */
+ for (ptr = pre_ldst_mems, prev_next_ptr_ptr = &pre_ldst_mems;
+ ptr != NULL;
+ ptr = *prev_next_ptr_ptr)
+ {
+ if (!AVAIL_STORE_LIST (ptr))
+ {
+ *prev_next_ptr_ptr = ptr->next;
+ free_ldst_entry (ptr);
+ }
+ else
+ prev_next_ptr_ptr = &ptr->next;
+ }
+
+ ret = enumerate_ldsts ();
+
+ if (gcse_file)
+ {
+ fprintf (gcse_file, "ST_avail and ST_antic (shown under loads..)\n");
+ print_ldst_list (gcse_file);
+ }
+
+ free (last_set_in);
+ free (already_set);
+ return ret;
}
-/* Make sure there isn't a buried reference in this pattern anywhere.
- If there is, invalidate the entry for it since we're not capable
- of fixing it up just yet.. We have to be sure we know about ALL
- loads since the aliasing code will allow all entries in the
- ld_motion list to not-alias itself. If we miss a load, we will get
- the wrong value since gcse might common it and we won't know to
- fix it up. */
+/* Check to see if the load X is aliased with STORE_PATTERN.
+ AFTER is true if we are checking the case when STORE_PATTERN occurs
+ after the X. */
-static void
-invalidate_any_buried_refs (x)
- rtx x;
+static bool
+load_kills_store (rtx x, rtx store_pattern, int after)
+{
+ if (after)
+ return anti_dependence (x, store_pattern);
+ else
+ return true_dependence (store_pattern, GET_MODE (store_pattern), x,
+ rtx_addr_varies_p);
+}
+
+/* Go through the entire insn X, looking for any loads which might alias
+ STORE_PATTERN. Return true if found.
+ AFTER is true if we are checking the case when STORE_PATTERN occurs
+ after the insn X. */
+
+static bool
+find_loads (rtx x, rtx store_pattern, int after)
{
const char * fmt;
int i, j;
- struct ls_expr * ptr;
+ int ret = false;
+
+ if (!x)
+ return false;
+
+ if (GET_CODE (x) == SET)
+ x = SET_SRC (x);
- /* Invalidate it in the list. */
- if (GET_CODE (x) == MEM && simple_mem (x))
+ if (MEM_P (x))
{
- ptr = ldst_entry (x);
- ptr->invalid = 1;
+ if (load_kills_store (x, store_pattern, after))
+ return true;
}
/* Recursively process the insn. */
fmt = GET_RTX_FORMAT (GET_CODE (x));
- for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
+ for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
{
if (fmt[i] == 'e')
- invalidate_any_buried_refs (XEXP (x, i));
+ ret |= find_loads (XEXP (x, i), store_pattern, after);
else if (fmt[i] == 'E')
for (j = XVECLEN (x, i) - 1; j >= 0; j--)
- invalidate_any_buried_refs (XVECEXP (x, i, j));
+ ret |= find_loads (XVECEXP (x, i, j), store_pattern, after);
}
+ return ret;
}
-/* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
- being defined as MEM loads and stores to symbols, with no
- side effects and no registers in the expression. If there are any
- uses/defs which don't match this criteria, it is invalidated and
- trimmed out later. */
+/* Check if INSN kills the store pattern X (is aliased with it).
+ AFTER is true if we are checking the case when store X occurs
+ after the insn. Return true if it it does. */
-static void
-compute_ld_motion_mems ()
+static bool
+store_killed_in_insn (rtx x, rtx x_regs, rtx insn, int after)
{
- struct ls_expr * ptr;
- basic_block bb;
- rtx insn;
+ rtx reg, base, note;
- pre_ldst_mems = NULL;
+ if (!INSN_P (insn))
+ return false;
- FOR_EACH_BB (bb)
+ if (CALL_P (insn))
{
- for (insn = bb->head;
- insn && insn != NEXT_INSN (bb->end);
- insn = NEXT_INSN (insn))
+ /* A normal or pure call might read from pattern,
+ but a const call will not. */
+ if (! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn))
+ return true;
+
+ /* But even a const call reads its parameters. Check whether the
+ base of some of registers used in mem is stack pointer. */
+ for (reg = x_regs; reg; reg = XEXP (reg, 1))
{
- if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
- {
- if (GET_CODE (PATTERN (insn)) == SET)
- {
- rtx src = SET_SRC (PATTERN (insn));
- rtx dest = SET_DEST (PATTERN (insn));
+ base = find_base_term (XEXP (reg, 0));
+ if (!base
+ || (GET_CODE (base) == ADDRESS
+ && GET_MODE (base) == Pmode
+ && XEXP (base, 0) == stack_pointer_rtx))
+ return true;
+ }
- /* Check for a simple LOAD... */
- if (GET_CODE (src) == MEM && simple_mem (src))
- {
- ptr = ldst_entry (src);
- if (GET_CODE (dest) == REG)
- ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
- else
- ptr->invalid = 1;
- }
- else
- {
- /* Make sure there isn't a buried load somewhere. */
- invalidate_any_buried_refs (src);
- }
+ return false;
+ }
- /* Check for stores. Don't worry about aliased ones, they
- will block any movement we might do later. We only care
- about this exact pattern since those are the only
- circumstance that we will ignore the aliasing info. */
- if (GET_CODE (dest) == MEM && simple_mem (dest))
- {
- ptr = ldst_entry (dest);
+ if (GET_CODE (PATTERN (insn)) == SET)
+ {
+ rtx pat = PATTERN (insn);
+ rtx dest = SET_DEST (pat);
- if (GET_CODE (src) != MEM
- && GET_CODE (src) != ASM_OPERANDS)
- ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
- else
- ptr->invalid = 1;
- }
- }
- else
- invalidate_any_buried_refs (PATTERN (insn));
+ if (GET_CODE (dest) == SIGN_EXTRACT
+ || GET_CODE (dest) == ZERO_EXTRACT)
+ dest = XEXP (dest, 0);
+
+ /* Check for memory stores to aliased objects. */
+ if (MEM_P (dest)
+ && !expr_equiv_p (dest, x))
+ {
+ if (after)
+ {
+ if (output_dependence (dest, x))
+ return true;
+ }
+ else
+ {
+ if (output_dependence (x, dest))
+ return true;
}
}
+ if (find_loads (SET_SRC (pat), x, after))
+ return true;
}
+ else if (find_loads (PATTERN (insn), x, after))
+ return true;
+
+ /* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
+ location aliased with X, then this insn kills X. */
+ note = find_reg_equal_equiv_note (insn);
+ if (! note)
+ return false;
+ note = XEXP (note, 0);
+
+ /* However, if the note represents a must alias rather than a may
+ alias relationship, then it does not kill X. */
+ if (expr_equiv_p (note, x))
+ return false;
+
+ /* See if there are any aliased loads in the note. */
+ return find_loads (note, x, after);
}
-/* Remove any references that have been either invalidated or are not in the
- expression list for pre gcse. */
+/* Returns true if the expression X is loaded or clobbered on or after INSN
+ within basic block BB. REGS_SET_AFTER is bitmap of registers set in
+ or after the insn. X_REGS is list of registers mentioned in X. If the store
+ is killed, return the last insn in that it occurs in FAIL_INSN. */
-static void
-trim_ld_motion_mems ()
+static bool
+store_killed_after (rtx x, rtx x_regs, rtx insn, basic_block bb,
+ int *regs_set_after, rtx *fail_insn)
{
- struct ls_expr * last = NULL;
- struct ls_expr * ptr = first_ls_expr ();
+ rtx last = BB_END (bb), act;
- while (ptr != NULL)
+ if (!store_ops_ok (x_regs, regs_set_after))
{
- int del = ptr->invalid;
- struct expr * expr = NULL;
+ /* We do not know where it will happen. */
+ if (fail_insn)
+ *fail_insn = NULL_RTX;
+ return true;
+ }
- /* Delete if entry has been made invalid. */
- if (!del)
+ /* Scan from the end, so that fail_insn is determined correctly. */
+ for (act = last; act != PREV_INSN (insn); act = PREV_INSN (act))
+ if (store_killed_in_insn (x, x_regs, act, false))
+ {
+ if (fail_insn)
+ *fail_insn = act;
+ return true;
+ }
+
+ return false;
+}
+
+/* Returns true if the expression X is loaded or clobbered on or before INSN
+ within basic block BB. X_REGS is list of registers mentioned in X.
+ REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
+static bool
+store_killed_before (rtx x, rtx x_regs, rtx insn, basic_block bb,
+ int *regs_set_before)
+{
+ rtx first = BB_HEAD (bb);
+
+ if (!store_ops_ok (x_regs, regs_set_before))
+ return true;
+
+ for ( ; insn != PREV_INSN (first); insn = PREV_INSN (insn))
+ if (store_killed_in_insn (x, x_regs, insn, true))
+ return true;
+
+ return false;
+}
+
+/* Fill in available, anticipatable, transparent and kill vectors in
+ STORE_DATA, based on lists of available and anticipatable stores. */
+static void
+build_store_vectors (void)
+{
+ basic_block bb;
+ int *regs_set_in_block;
+ rtx insn, st;
+ struct ls_expr * ptr;
+ unsigned regno;
+
+ /* Build the gen_vector. This is any store in the table which is not killed
+ by aliasing later in its block. */
+ ae_gen = sbitmap_vector_alloc (last_basic_block, num_stores);
+ sbitmap_vector_zero (ae_gen, last_basic_block);
+
+ st_antloc = sbitmap_vector_alloc (last_basic_block, num_stores);
+ sbitmap_vector_zero (st_antloc, last_basic_block);
+
+ for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
+ {
+ for (st = AVAIL_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
{
- unsigned int i;
+ insn = XEXP (st, 0);
+ bb = BLOCK_FOR_INSN (insn);
- del = 1;
- /* Delete if we cannot find this mem in the expression list. */
- for (i = 0; i < expr_hash_table.size && del; i++)
+ /* If we've already seen an available expression in this block,
+ we can delete this one (It occurs earlier in the block). We'll
+ copy the SRC expression to an unused register in case there
+ are any side effects. */
+ if (TEST_BIT (ae_gen[bb->index], ptr->index))
{
- for (expr = expr_hash_table.table[i];
- expr != NULL;
- expr = expr->next_same_hash)
- if (expr_equiv_p (expr->expr, ptr->pattern))
- {
- del = 0;
- break;
- }
+ rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
+ if (gcse_file)
+ fprintf (gcse_file, "Removing redundant store:\n");
+ replace_store_insn (r, XEXP (st, 0), bb, ptr);
+ continue;
}
+ SET_BIT (ae_gen[bb->index], ptr->index);
}
- if (del)
+ for (st = ANTIC_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
{
- if (last != NULL)
+ insn = XEXP (st, 0);
+ bb = BLOCK_FOR_INSN (insn);
+ SET_BIT (st_antloc[bb->index], ptr->index);
+ }
+ }
+
+ ae_kill = sbitmap_vector_alloc (last_basic_block, num_stores);
+ sbitmap_vector_zero (ae_kill, last_basic_block);
+
+ transp = sbitmap_vector_alloc (last_basic_block, num_stores);
+ sbitmap_vector_zero (transp, last_basic_block);
+ regs_set_in_block = xmalloc (sizeof (int) * max_gcse_regno);
+
+ FOR_EACH_BB (bb)
+ {
+ for (regno = 0; regno < max_gcse_regno; regno++)
+ regs_set_in_block[regno] = TEST_BIT (reg_set_in_block[bb->index], regno);
+
+ for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
+ {
+ if (store_killed_after (ptr->pattern, ptr->pattern_regs, BB_HEAD (bb),
+ bb, regs_set_in_block, NULL))
{
- last->next = ptr->next;
- free_ldst_entry (ptr);
- ptr = last->next;
+ /* It should not be necessary to consider the expression
+ killed if it is both anticipatable and available. */
+ if (!TEST_BIT (st_antloc[bb->index], ptr->index)
+ || !TEST_BIT (ae_gen[bb->index], ptr->index))
+ SET_BIT (ae_kill[bb->index], ptr->index);
}
else
- {
- pre_ldst_mems = pre_ldst_mems->next;
- free_ldst_entry (ptr);
- ptr = pre_ldst_mems;
- }
- }
- else
- {
- /* Set the expression field if we are keeping it. */
- last = ptr;
- ptr->expr = expr;
- ptr = ptr->next;
+ SET_BIT (transp[bb->index], ptr->index);
}
}
- /* Show the world what we've found. */
- if (gcse_file && pre_ldst_mems != NULL)
- print_ldst_list (gcse_file);
+ free (regs_set_in_block);
+
+ if (gcse_file)
+ {
+ dump_sbitmap_vector (gcse_file, "st_antloc", "", st_antloc, last_basic_block);
+ dump_sbitmap_vector (gcse_file, "st_kill", "", ae_kill, last_basic_block);
+ dump_sbitmap_vector (gcse_file, "Transpt", "", transp, last_basic_block);
+ dump_sbitmap_vector (gcse_file, "st_avloc", "", ae_gen, last_basic_block);
+ }
}
-/* This routine will take an expression which we are replacing with
- a reaching register, and update any stores that are needed if
- that expression is in the ld_motion list. Stores are updated by
- copying their SRC to the reaching register, and then storeing
- the reaching register into the store location. These keeps the
- correct value in the reaching register for the loads. */
+/* Insert an instruction at the beginning of a basic block, and update
+ the BB_HEAD if needed. */
static void
-update_ld_motion_stores (expr)
- struct expr * expr;
+insert_insn_start_bb (rtx insn, basic_block bb)
{
- struct ls_expr * mem_ptr;
+ /* Insert at start of successor block. */
+ rtx prev = PREV_INSN (BB_HEAD (bb));
+ rtx before = BB_HEAD (bb);
+ while (before != 0)
+ {
+ if (! LABEL_P (before)
+ && (! NOTE_P (before)
+ || NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK))
+ break;
+ prev = before;
+ if (prev == BB_END (bb))
+ break;
+ before = NEXT_INSN (before);
+ }
- if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
+ insn = emit_insn_after (insn, prev);
+
+ if (gcse_file)
{
- /* We can try to find just the REACHED stores, but is shouldn't
- matter to set the reaching reg everywhere... some might be
- dead and should be eliminated later. */
+ fprintf (gcse_file, "STORE_MOTION insert store at start of BB %d:\n",
+ bb->index);
+ print_inline_rtx (gcse_file, insn, 6);
+ fprintf (gcse_file, "\n");
+ }
+}
- /* We replace SET mem = expr with
- SET reg = expr
- SET mem = reg , where reg is the
- reaching reg used in the load. */
- rtx list = mem_ptr->stores;
+/* This routine will insert a store on an edge. EXPR is the ldst entry for
+ the memory reference, and E is the edge to insert it on. Returns nonzero
+ if an edge insertion was performed. */
- for ( ; list != NULL_RTX; list = XEXP (list, 1))
+static int
+insert_store (struct ls_expr * expr, edge e)
+{
+ rtx reg, insn;
+ basic_block bb;
+ edge tmp;
+
+ /* We did all the deleted before this insert, so if we didn't delete a
+ store, then we haven't set the reaching reg yet either. */
+ if (expr->reaching_reg == NULL_RTX)
+ return 0;
+
+ if (e->flags & EDGE_FAKE)
+ return 0;
+
+ reg = expr->reaching_reg;
+ insn = gen_move_insn (copy_rtx (expr->pattern), reg);
+
+ /* If we are inserting this expression on ALL predecessor edges of a BB,
+ insert it at the start of the BB, and reset the insert bits on the other
+ edges so we don't try to insert it on the other edges. */
+ bb = e->dest;
+ for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
+ if (!(tmp->flags & EDGE_FAKE))
+ {
+ int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
+ if (index == EDGE_INDEX_NO_EDGE)
+ abort ();
+ if (! TEST_BIT (pre_insert_map[index], expr->index))
+ break;
+ }
+
+ /* If tmp is NULL, we found an insertion on every edge, blank the
+ insertion vector for these edges, and insert at the start of the BB. */
+ if (!tmp && bb != EXIT_BLOCK_PTR)
+ {
+ for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
{
- rtx insn = XEXP (list, 0);
- rtx pat = PATTERN (insn);
- rtx src = SET_SRC (pat);
- rtx reg = expr->reaching_reg;
- rtx copy, new;
+ int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
+ RESET_BIT (pre_insert_map[index], expr->index);
+ }
+ insert_insn_start_bb (insn, bb);
+ return 0;
+ }
- /* If we've already copied it, continue. */
- if (expr->reaching_reg == src)
- continue;
+ /* We can't insert on this edge, so we'll insert at the head of the
+ successors block. See Morgan, sec 10.5. */
+ if ((e->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
+ {
+ insert_insn_start_bb (insn, bb);
+ return 0;
+ }
- if (gcse_file)
- {
- fprintf (gcse_file, "PRE: store updated with reaching reg ");
- print_rtl (gcse_file, expr->reaching_reg);
- fprintf (gcse_file, ":\n ");
- print_inline_rtx (gcse_file, insn, 8);
- fprintf (gcse_file, "\n");
+ insert_insn_on_edge (insn, e);
+
+ if (gcse_file)
+ {
+ fprintf (gcse_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
+ e->src->index, e->dest->index);
+ print_inline_rtx (gcse_file, insn, 6);
+ fprintf (gcse_file, "\n");
+ }
+
+ return 1;
+}
+
+/* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
+ memory location in SMEXPR set in basic block BB.
+
+ This could be rather expensive. */
+
+static void
+remove_reachable_equiv_notes (basic_block bb, struct ls_expr *smexpr)
+{
+ edge *stack = xmalloc (sizeof (edge) * n_basic_blocks), act;
+ sbitmap visited = sbitmap_alloc (last_basic_block);
+ int stack_top = 0;
+ rtx last, insn, note;
+ rtx mem = smexpr->pattern;
+
+ sbitmap_zero (visited);
+ act = bb->succ;
+
+ while (1)
+ {
+ if (!act)
+ {
+ if (!stack_top)
+ {
+ free (stack);
+ sbitmap_free (visited);
+ return;
}
+ act = stack[--stack_top];
+ }
+ bb = act->dest;
- copy = gen_move_insn ( reg, SET_SRC (pat));
- new = emit_insn_before (copy, insn);
- record_one_set (REGNO (reg), new);
- SET_SRC (pat) = reg;
-
- /* un-recognize this pattern since it's probably different now. */
- INSN_CODE (insn) = -1;
- gcse_create_count++;
+ if (bb == EXIT_BLOCK_PTR
+ || TEST_BIT (visited, bb->index))
+ {
+ act = act->succ_next;
+ continue;
}
- }
-}
-\f
-/* Store motion code. */
+ SET_BIT (visited, bb->index);
-/* This is used to communicate the target bitvector we want to use in the
- reg_set_info routine when called via the note_stores mechanism. */
-static sbitmap * regvec;
+ if (TEST_BIT (st_antloc[bb->index], smexpr->index))
+ {
+ for (last = ANTIC_STORE_LIST (smexpr);
+ BLOCK_FOR_INSN (XEXP (last, 0)) != bb;
+ last = XEXP (last, 1))
+ continue;
+ last = XEXP (last, 0);
+ }
+ else
+ last = NEXT_INSN (BB_END (bb));
-/* Used in computing the reverse edge graph bit vectors. */
-static sbitmap * st_antloc;
+ for (insn = BB_HEAD (bb); insn != last; insn = NEXT_INSN (insn))
+ if (INSN_P (insn))
+ {
+ note = find_reg_equal_equiv_note (insn);
+ if (!note || !expr_equiv_p (XEXP (note, 0), mem))
+ continue;
-/* Global holding the number of store expressions we are dealing with. */
-static int num_stores;
+ if (gcse_file)
+ fprintf (gcse_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
+ INSN_UID (insn));
+ remove_note (insn, note);
+ }
+ act = act->succ_next;
+ if (bb->succ)
+ {
+ if (act)
+ stack[stack_top++] = act;
+ act = bb->succ;
+ }
+ }
+}
-/* Checks to set if we need to mark a register set. Called from note_stores. */
+/* This routine will replace a store with a SET to a specified register. */
static void
-reg_set_info (dest, setter, data)
- rtx dest, setter ATTRIBUTE_UNUSED;
- void * data ATTRIBUTE_UNUSED;
+replace_store_insn (rtx reg, rtx del, basic_block bb, struct ls_expr *smexpr)
{
- if (GET_CODE (dest) == SUBREG)
- dest = SUBREG_REG (dest);
-
- if (GET_CODE (dest) == REG)
- SET_BIT (*regvec, REGNO (dest));
-}
+ rtx insn, mem, note, set, ptr;
-/* Return nonzero if the register operands of expression X are killed
- anywhere in basic block BB. */
+ mem = smexpr->pattern;
+ insn = gen_move_insn (reg, SET_SRC (single_set (del)));
+ insn = emit_insn_after (insn, del);
-static int
-store_ops_ok (x, bb)
- rtx x;
- basic_block bb;
-{
- int i;
- enum rtx_code code;
- const char * fmt;
+ if (gcse_file)
+ {
+ fprintf (gcse_file,
+ "STORE_MOTION delete insn in BB %d:\n ", bb->index);
+ print_inline_rtx (gcse_file, del, 6);
+ fprintf (gcse_file, "\nSTORE MOTION replaced with insn:\n ");
+ print_inline_rtx (gcse_file, insn, 6);
+ fprintf (gcse_file, "\n");
+ }
- /* Repeat is used to turn tail-recursion into iteration. */
- repeat:
+ for (ptr = ANTIC_STORE_LIST (smexpr); ptr; ptr = XEXP (ptr, 1))
+ if (XEXP (ptr, 0) == del)
+ {
+ XEXP (ptr, 0) = insn;
+ break;
+ }
+ delete_insn (del);
- if (x == 0)
- return 1;
+ /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
+ they are no longer accurate provided that they are reached by this
+ definition, so drop them. */
+ for (; insn != NEXT_INSN (BB_END (bb)); insn = NEXT_INSN (insn))
+ if (INSN_P (insn))
+ {
+ set = single_set (insn);
+ if (!set)
+ continue;
+ if (expr_equiv_p (SET_DEST (set), mem))
+ return;
+ note = find_reg_equal_equiv_note (insn);
+ if (!note || !expr_equiv_p (XEXP (note, 0), mem))
+ continue;
- code = GET_CODE (x);
- switch (code)
- {
- case REG:
- /* If a reg has changed after us in this
- block, the operand has been killed. */
- return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
+ if (gcse_file)
+ fprintf (gcse_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
+ INSN_UID (insn));
+ remove_note (insn, note);
+ }
+ remove_reachable_equiv_notes (bb, smexpr);
+}
- case MEM:
- x = XEXP (x, 0);
- goto repeat;
- case PRE_DEC:
- case PRE_INC:
- case POST_DEC:
- case POST_INC:
- return 0;
+/* Delete a store, but copy the value that would have been stored into
+ the reaching_reg for later storing. */
- case PC:
- case CC0: /*FIXME*/
- case CONST:
- case CONST_INT:
- case CONST_DOUBLE:
- case CONST_VECTOR:
- case SYMBOL_REF:
- case LABEL_REF:
- case ADDR_VEC:
- case ADDR_DIFF_VEC:
- return 1;
+static void
+delete_store (struct ls_expr * expr, basic_block bb)
+{
+ rtx reg, i, del;
- default:
- break;
- }
+ if (expr->reaching_reg == NULL_RTX)
+ expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
- i = GET_RTX_LENGTH (code) - 1;
- fmt = GET_RTX_FORMAT (code);
+ reg = expr->reaching_reg;
- for (; i >= 0; i--)
+ for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
{
- if (fmt[i] == 'e')
+ del = XEXP (i, 0);
+ if (BLOCK_FOR_INSN (del) == bb)
{
- rtx tem = XEXP (x, i);
+ /* We know there is only one since we deleted redundant
+ ones during the available computation. */
+ replace_store_insn (reg, del, bb, expr);
+ break;
+ }
+ }
+}
- /* If we are about to do the last recursive call
- needed at this level, change it into iteration.
- This function is called enough to be worth it. */
- if (i == 0)
- {
- x = tem;
- goto repeat;
- }
+/* Free memory used by store motion. */
- if (! store_ops_ok (tem, bb))
- return 0;
- }
- else if (fmt[i] == 'E')
- {
- int j;
+static void
+free_store_memory (void)
+{
+ free_ldst_mems ();
- for (j = 0; j < XVECLEN (x, i); j++)
- {
- if (! store_ops_ok (XVECEXP (x, i, j), bb))
- return 0;
- }
- }
- }
+ if (ae_gen)
+ sbitmap_vector_free (ae_gen);
+ if (ae_kill)
+ sbitmap_vector_free (ae_kill);
+ if (transp)
+ sbitmap_vector_free (transp);
+ if (st_antloc)
+ sbitmap_vector_free (st_antloc);
+ if (pre_insert_map)
+ sbitmap_vector_free (pre_insert_map);
+ if (pre_delete_map)
+ sbitmap_vector_free (pre_delete_map);
+ if (reg_set_in_block)
+ sbitmap_vector_free (reg_set_in_block);
- return 1;
+ ae_gen = ae_kill = transp = st_antloc = NULL;
+ pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
}
-/* Determine whether insn is MEM store pattern that we will consider moving. */
+/* Perform store motion. Much like gcse, except we move expressions the
+ other way by looking at the flowgraph in reverse. */
static void
-find_moveable_store (insn)
- rtx insn;
+store_motion (void)
{
+ basic_block bb;
+ int x;
struct ls_expr * ptr;
- rtx dest = PATTERN (insn);
-
- if (GET_CODE (dest) != SET
- || GET_CODE (SET_SRC (dest)) == ASM_OPERANDS)
- return;
+ int update_flow = 0;
- dest = SET_DEST (dest);
+ if (gcse_file)
+ {
+ fprintf (gcse_file, "before store motion\n");
+ print_rtl (gcse_file, get_insns ());
+ }
- if (GET_CODE (dest) != MEM || MEM_VOLATILE_P (dest)
- || GET_MODE (dest) == BLKmode)
- return;
+ init_alias_analysis ();
- if (GET_CODE (XEXP (dest, 0)) != SYMBOL_REF)
+ /* Find all the available and anticipatable stores. */
+ num_stores = compute_store_table ();
+ if (num_stores == 0)
+ {
+ sbitmap_vector_free (reg_set_in_block);
+ end_alias_analysis ();
return;
+ }
- if (rtx_varies_p (XEXP (dest, 0), 0))
- return;
+ /* Now compute kill & transp vectors. */
+ build_store_vectors ();
+ add_noreturn_fake_exit_edges ();
+ connect_infinite_loops_to_exit ();
- ptr = ldst_entry (dest);
- ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
+ edge_list = pre_edge_rev_lcm (gcse_file, num_stores, transp, ae_gen,
+ st_antloc, ae_kill, &pre_insert_map,
+ &pre_delete_map);
+
+ /* Now we want to insert the new stores which are going to be needed. */
+ for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
+ {
+ FOR_EACH_BB (bb)
+ if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
+ delete_store (ptr, bb);
+
+ for (x = 0; x < NUM_EDGES (edge_list); x++)
+ if (TEST_BIT (pre_insert_map[x], ptr->index))
+ update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
+ }
+
+ if (update_flow)
+ commit_edge_insertions ();
+
+ free_store_memory ();
+ free_edge_list (edge_list);
+ remove_fake_edges ();
+ end_alias_analysis ();
}
-/* Perform store motion. Much like gcse, except we move expressions the
- other way by looking at the flowgraph in reverse. */
+\f
+/* Entry point for jump bypassing optimization pass. */
-static int
-compute_store_table ()
+int
+bypass_jumps (FILE *file)
{
- int ret;
- basic_block bb;
- unsigned regno;
- rtx insn, pat;
+ int changed;
+
+ /* We do not construct an accurate cfg in functions which call
+ setjmp, so just punt to be safe. */
+ if (current_function_calls_setjmp)
+ return 0;
+
+ /* For calling dump_foo fns from gdb. */
+ debug_stderr = stderr;
+ gcse_file = file;
+ /* Identify the basic block information for this function, including
+ successors and predecessors. */
max_gcse_regno = max_reg_num ();
- reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (last_basic_block,
- max_gcse_regno);
- sbitmap_vector_zero (reg_set_in_block, last_basic_block);
- pre_ldst_mems = 0;
+ if (file)
+ dump_flow_info (file);
- /* Find all the stores we care about. */
- FOR_EACH_BB (bb)
- {
- regvec = & (reg_set_in_block[bb->index]);
- for (insn = bb->end;
- insn && insn != PREV_INSN (bb->end);
- insn = PREV_INSN (insn))
- {
- /* Ignore anything that is not a normal insn. */
- if (! INSN_P (insn))
- continue;
+ /* Return if there's nothing to do, or it is too expensive. */
+ if (n_basic_blocks <= 1 || is_too_expensive (_ ("jump bypassing disabled")))
+ return 0;
- if (GET_CODE (insn) == CALL_INSN)
- {
- bool clobbers_all = false;
-#ifdef NON_SAVING_SETJMP
- if (NON_SAVING_SETJMP
- && find_reg_note (insn, REG_SETJMP, NULL_RTX))
- clobbers_all = true;
-#endif
+ gcc_obstack_init (&gcse_obstack);
+ bytes_used = 0;
- for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
- if (clobbers_all
- || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
- SET_BIT (reg_set_in_block[bb->index], regno);
- }
+ /* We need alias. */
+ init_alias_analysis ();
+
+ /* Record where pseudo-registers are set. This data is kept accurate
+ during each pass. ??? We could also record hard-reg information here
+ [since it's unchanging], however it is currently done during hash table
+ computation.
- pat = PATTERN (insn);
- note_stores (pat, reg_set_info, NULL);
+ It may be tempting to compute MEM set information here too, but MEM sets
+ will be subject to code motion one day and thus we need to compute
+ information about memory sets when we build the hash tables. */
- /* Now that we've marked regs, look for stores. */
- if (GET_CODE (pat) == SET)
- find_moveable_store (insn);
- }
- }
+ alloc_reg_set_mem (max_gcse_regno);
+ compute_sets (get_insns ());
- ret = enumerate_ldsts ();
+ max_gcse_regno = max_reg_num ();
+ alloc_gcse_mem (get_insns ());
+ changed = one_cprop_pass (1, 1, 1);
+ free_gcse_mem ();
- if (gcse_file)
+ if (file)
{
- fprintf (gcse_file, "Store Motion Expressions.\n");
- print_ldst_list (gcse_file);
+ fprintf (file, "BYPASS of %s: %d basic blocks, ",
+ current_function_name (), n_basic_blocks);
+ fprintf (file, "%d bytes\n\n", bytes_used);
}
- return ret;
-}
+ obstack_free (&gcse_obstack, NULL);
+ free_reg_set_mem ();
-/* Check to see if the load X is aliased with STORE_PATTERN. */
+ /* We are finished with alias. */
+ end_alias_analysis ();
+ allocate_reg_info (max_reg_num (), FALSE, FALSE);
-static int
-load_kills_store (x, store_pattern)
- rtx x, store_pattern;
-{
- if (true_dependence (x, GET_MODE (x), store_pattern, rtx_addr_varies_p))
- return 1;
- return 0;
+ return changed;
}
-/* Go through the entire insn X, looking for any loads which might alias
- STORE_PATTERN. Return 1 if found. */
+/* Return true if the graph is too expensive to optimize. PASS is the
+ optimization about to be performed. */
-static int
-find_loads (x, store_pattern)
- rtx x, store_pattern;
+static bool
+is_too_expensive (const char *pass)
{
- const char * fmt;
- int i, j;
- int ret = 0;
-
- if (!x)
- return 0;
-
- if (GET_CODE (x) == SET)
- x = SET_SRC (x);
+ /* Trying to perform global optimizations on flow graphs which have
+ a high connectivity will take a long time and is unlikely to be
+ particularly useful.
- if (GET_CODE (x) == MEM)
+ In normal circumstances a cfg should have about twice as many
+ edges as blocks. But we do not want to punish small functions
+ which have a couple switch statements. Rather than simply
+ threshold the number of blocks, uses something with a more
+ graceful degradation. */
+ if (n_edges > 20000 + n_basic_blocks * 4)
{
- if (load_kills_store (x, store_pattern))
- return 1;
- }
+ if (warn_disabled_optimization)
+ warning ("%s: %d basic blocks and %d edges/basic block",
+ pass, n_basic_blocks, n_edges / n_basic_blocks);
- /* Recursively process the insn. */
- fmt = GET_RTX_FORMAT (GET_CODE (x));
+ return true;
+ }
- for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
+ /* If allocating memory for the cprop bitmap would take up too much
+ storage it's better just to disable the optimization. */
+ if ((n_basic_blocks
+ * SBITMAP_SET_SIZE (max_reg_num ())
+ * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
{
- if (fmt[i] == 'e')
- ret |= find_loads (XEXP (x, i), store_pattern);
- else if (fmt[i] == 'E')
- for (j = XVECLEN (x, i) - 1; j >= 0; j--)
- ret |= find_loads (XVECEXP (x, i, j), store_pattern);
+ if (warn_disabled_optimization)
+ warning ("%s: %d basic blocks and %d registers",
+ pass, n_basic_blocks, max_reg_num ());
+
+ return true;
}
- return ret;
+
+ return false;
}
-/* Check if INSN kills the store pattern X (is aliased with it).
- Return 1 if it it does. */
+/* The following code implements gcse after reload, the purpose of this
+ pass is to cleanup redundant loads generated by reload and other
+ optimizations that come after gcse. It searches for simple inter-block
+ redundancies and tries to eliminate them by adding moves and loads
+ in cold places. */
-static int
-store_killed_in_insn (x, insn)
- rtx x, insn;
+/* The following structure holds the information about the occurrences of
+ the redundant instructions. */
+struct unoccr
{
- if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
- return 0;
+ struct unoccr *next;
+ edge pred;
+ rtx insn;
+};
- if (GET_CODE (insn) == CALL_INSN)
- {
- /* A normal or pure call might read from pattern,
- but a const call will not. */
- return ! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn);
- }
+static bool reg_used_on_edge (rtx, edge);
+static rtx reg_set_between_after_reload_p (rtx, rtx, rtx);
+static rtx reg_used_between_after_reload_p (rtx, rtx, rtx);
+static rtx get_avail_load_store_reg (rtx);
+static bool is_jump_table_basic_block (basic_block);
+static bool bb_has_well_behaved_predecessors (basic_block);
+static struct occr* get_bb_avail_insn (basic_block, struct occr *);
+static void hash_scan_set_after_reload (rtx, rtx, struct hash_table *);
+static void compute_hash_table_after_reload (struct hash_table *);
+static void eliminate_partially_redundant_loads (basic_block,
+ rtx,
+ struct expr *);
+static void gcse_after_reload (void);
+static struct occr* get_bb_avail_insn (basic_block, struct occr *);
+void gcse_after_reload_main (rtx, FILE *);
+
+
+/* Check if register REG is used in any insn waiting to be inserted on E.
+ Assumes no such insn can be a CALL_INSN; if so call reg_used_between_p
+ with PREV(insn),NEXT(insn) instead of calling
+ reg_overlap_mentioned_p. */
- if (GET_CODE (PATTERN (insn)) == SET)
- {
- rtx pat = PATTERN (insn);
- /* Check for memory stores to aliased objects. */
- if (GET_CODE (SET_DEST (pat)) == MEM && !expr_equiv_p (SET_DEST (pat), x))
- /* pretend its a load and check for aliasing. */
- if (find_loads (SET_DEST (pat), x))
- return 1;
- return find_loads (SET_SRC (pat), x);
- }
- else
- return find_loads (PATTERN (insn), x);
+static bool
+reg_used_on_edge (rtx reg, edge e)
+{
+ rtx insn;
+
+ for (insn = e->insns.r; insn; insn = NEXT_INSN (insn))
+ if (INSN_P (insn) && reg_overlap_mentioned_p (reg, PATTERN (insn)))
+ return true;
+
+ return false;
}
-/* Returns 1 if the expression X is loaded or clobbered on or after INSN
- within basic block BB. */
+/* Return the insn that sets register REG or clobbers it in between
+ FROM_INSN and TO_INSN (exclusive of those two).
+ Just like reg_set_between but for hard registers and not pseudos. */
-static int
-store_killed_after (x, insn, bb)
- rtx x, insn;
- basic_block bb;
+static rtx
+reg_set_between_after_reload_p (rtx reg, rtx from_insn, rtx to_insn)
{
- rtx last = bb->end;
+ rtx insn;
+ int regno;
- if (insn == last)
- return 0;
+ if (! REG_P (reg))
+ abort ();
+ regno = REGNO (reg);
- /* Check if the register operands of the store are OK in this block.
- Note that if registers are changed ANYWHERE in the block, we'll
- decide we can't move it, regardless of whether it changed above
- or below the store. This could be improved by checking the register
- operands while looking for aliasing in each insn. */
- if (!store_ops_ok (XEXP (x, 0), bb))
- return 1;
+ /* We are called after register allocation. */
+ if (regno >= FIRST_PSEUDO_REGISTER)
+ abort ();
- for ( ; insn && insn != NEXT_INSN (last); insn = NEXT_INSN (insn))
- if (store_killed_in_insn (x, insn))
- return 1;
+ if (from_insn == to_insn)
+ return NULL_RTX;
- return 0;
+ for (insn = NEXT_INSN (from_insn);
+ insn != to_insn;
+ insn = NEXT_INSN (insn))
+ {
+ if (INSN_P (insn))
+ {
+ if (FIND_REG_INC_NOTE (insn, reg)
+ || (CALL_P (insn)
+ && call_used_regs[regno])
+ || find_reg_fusage (insn, CLOBBER, reg))
+ return insn;
+ }
+ if (set_of (reg, insn) != NULL_RTX)
+ return insn;
+ }
+ return NULL_RTX;
}
-/* Returns 1 if the expression X is loaded or clobbered on or before INSN
- within basic block BB. */
-static int
-store_killed_before (x, insn, bb)
- rtx x, insn;
- basic_block bb;
+/* Return the insn that uses register REG in between FROM_INSN and TO_INSN
+ (exclusive of those two). Similar to reg_used_between but for hard
+ registers and not pseudos. */
+
+static rtx
+reg_used_between_after_reload_p (rtx reg, rtx from_insn, rtx to_insn)
{
- rtx first = bb->head;
+ rtx insn;
+ int regno;
- if (insn == first)
- return store_killed_in_insn (x, insn);
+ if (! REG_P (reg))
+ return to_insn;
+ regno = REGNO (reg);
- /* Check if the register operands of the store are OK in this block.
- Note that if registers are changed ANYWHERE in the block, we'll
- decide we can't move it, regardless of whether it changed above
- or below the store. This could be improved by checking the register
- operands while looking for aliasing in each insn. */
- if (!store_ops_ok (XEXP (x, 0), bb))
- return 1;
+ /* We are called after register allocation. */
+ if (regno >= FIRST_PSEUDO_REGISTER)
+ abort ();
+ if (from_insn == to_insn)
+ return NULL_RTX;
- for ( ; insn && insn != PREV_INSN (first); insn = PREV_INSN (insn))
- if (store_killed_in_insn (x, insn))
- return 1;
+ for (insn = NEXT_INSN (from_insn);
+ insn != to_insn;
+ insn = NEXT_INSN (insn))
+ if (INSN_P (insn)
+ && (reg_overlap_mentioned_p (reg, PATTERN (insn))
+ || (CALL_P (insn)
+ && call_used_regs[regno])
+ || find_reg_fusage (insn, USE, reg)
+ || find_reg_fusage (insn, CLOBBER, reg)))
+ return insn;
+ return NULL_RTX;
+}
- return 0;
+/* Return the loaded/stored register of a load/store instruction. */
+
+static rtx
+get_avail_load_store_reg (rtx insn)
+{
+ if (REG_P (SET_DEST (PATTERN (insn)))) /* A load. */
+ return SET_DEST(PATTERN(insn));
+ if (REG_P (SET_SRC (PATTERN (insn)))) /* A store. */
+ return SET_SRC (PATTERN (insn));
+ abort ();
}
-#define ANTIC_STORE_LIST(x) ((x)->loads)
-#define AVAIL_STORE_LIST(x) ((x)->stores)
+/* Don't handle ABNORMAL edges or jump tables. */
-/* Given the table of available store insns at the end of blocks,
- determine which ones are not killed by aliasing, and generate
- the appropriate vectors for gen and killed. */
-static void
-build_store_vectors ()
+static bool
+is_jump_table_basic_block (basic_block bb)
{
- basic_block bb, b;
- rtx insn, st;
- struct ls_expr * ptr;
+ rtx insn = BB_END (bb);
- /* Build the gen_vector. This is any store in the table which is not killed
- by aliasing later in its block. */
- ae_gen = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
- sbitmap_vector_zero (ae_gen, last_basic_block);
+ if (JUMP_TABLE_DATA_P (insn))
+ return true;
+ return false;
+}
- st_antloc = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
- sbitmap_vector_zero (st_antloc, last_basic_block);
+/* Return nonzero if the predecessors of BB are "well behaved". */
- for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
- {
- /* Put all the stores into either the antic list, or the avail list,
- or both. */
- rtx store_list = ptr->stores;
- ptr->stores = NULL_RTX;
+static bool
+bb_has_well_behaved_predecessors (basic_block bb)
+{
+ edge pred;
- for (st = store_list; st != NULL; st = XEXP (st, 1))
- {
- insn = XEXP (st, 0);
- bb = BLOCK_FOR_INSN (insn);
+ if (! bb->pred)
+ return false;
+ for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
+ if (((pred->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (pred))
+ || is_jump_table_basic_block (pred->src))
+ return false;
+ return true;
+}
- if (!store_killed_after (ptr->pattern, insn, bb))
- {
- /* If we've already seen an available expression in this block,
- we can delete the one we saw already (It occurs earlier in
- the block), and replace it with this one). We'll copy the
- old SRC expression to an unused register in case there
- are any side effects. */
- if (TEST_BIT (ae_gen[bb->index], ptr->index))
- {
- /* Find previous store. */
- rtx st;
- for (st = AVAIL_STORE_LIST (ptr); st ; st = XEXP (st, 1))
- if (BLOCK_FOR_INSN (XEXP (st, 0)) == bb)
- break;
- if (st)
- {
- rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
- if (gcse_file)
- fprintf (gcse_file, "Removing redundant store:\n");
- replace_store_insn (r, XEXP (st, 0), bb);
- XEXP (st, 0) = insn;
- continue;
- }
- }
- SET_BIT (ae_gen[bb->index], ptr->index);
- AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn,
- AVAIL_STORE_LIST (ptr));
- }
- if (!store_killed_before (ptr->pattern, insn, bb))
- {
- SET_BIT (st_antloc[BLOCK_NUM (insn)], ptr->index);
- ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (insn,
- ANTIC_STORE_LIST (ptr));
- }
- }
+/* Search for the occurrences of expression in BB. */
- /* Free the original list of store insns. */
- free_INSN_LIST_list (&store_list);
- }
+static struct occr*
+get_bb_avail_insn (basic_block bb, struct occr *occr)
+{
+ for (; occr != NULL; occr = occr->next)
+ if (BLOCK_FOR_INSN (occr->insn)->index == bb->index)
+ return occr;
+ return NULL;
+}
- ae_kill = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
- sbitmap_vector_zero (ae_kill, last_basic_block);
+/* Perform partial GCSE pass after reload, try to eliminate redundant loads
+ created by the reload pass. We try to look for a full or partial
+ redundant loads fed by one or more loads/stores in predecessor BBs,
+ and try adding loads to make them fully redundant. We also check if
+ it's worth adding loads to be able to delete the redundant load.
- transp = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
- sbitmap_vector_zero (transp, last_basic_block);
+ Algorithm:
+ 1. Build available expressions hash table:
+ For each load/store instruction, if the loaded/stored memory didn't
+ change until the end of the basic block add this memory expression to
+ the hash table.
+ 2. Perform Redundancy elimination:
+ For each load instruction do the following:
+ perform partial redundancy elimination, check if it's worth adding
+ loads to make the load fully redundant. If so add loads and
+ register copies and delete the load.
- for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
- FOR_EACH_BB (b)
- {
- if (store_killed_after (ptr->pattern, b->head, b))
- {
- /* The anticipatable expression is not killed if it's gen'd. */
- /*
- We leave this check out for now. If we have a code sequence
- in a block which looks like:
- ST MEMa = x
- L y = MEMa
- ST MEMa = z
- We should flag this as having an ANTIC expression, NOT
- transparent, NOT killed, and AVAIL.
- Unfortunately, since we haven't re-written all loads to
- use the reaching reg, we'll end up doing an incorrect
- Load in the middle here if we push the store down. It happens in
- gcc.c-torture/execute/960311-1.c with -O3
- If we always kill it in this case, we'll sometimes do
- unnecessary work, but it shouldn't actually hurt anything.
- if (!TEST_BIT (ae_gen[b], ptr->index)). */
- SET_BIT (ae_kill[b->index], ptr->index);
- }
- else
- SET_BIT (transp[b->index], ptr->index);
- }
+ Future enhancement:
+ if loaded register is used/defined between load and some store,
+ look for some other free register between load and all its stores,
+ and replace load with a copy from this register to the loaded
+ register. */
- /* Any block with no exits calls some non-returning function, so
- we better mark the store killed here, or we might not store to
- it at all. If we knew it was abort, we wouldn't have to store,
- but we don't know that for sure. */
- if (gcse_file)
- {
- fprintf (gcse_file, "ST_avail and ST_antic (shown under loads..)\n");
- print_ldst_list (gcse_file);
- dump_sbitmap_vector (gcse_file, "st_antloc", "", st_antloc, last_basic_block);
- dump_sbitmap_vector (gcse_file, "st_kill", "", ae_kill, last_basic_block);
- dump_sbitmap_vector (gcse_file, "Transpt", "", transp, last_basic_block);
- dump_sbitmap_vector (gcse_file, "st_avloc", "", ae_gen, last_basic_block);
- }
-}
-/* Insert an instruction at the beginning of a basic block, and update
- the BLOCK_HEAD if needed. */
+/* This handles the case where several stores feed a partially redundant
+ load. It checks if the redundancy elimination is possible and if it's
+ worth it. */
static void
-insert_insn_start_bb (insn, bb)
- rtx insn;
- basic_block bb;
+eliminate_partially_redundant_loads (basic_block bb, rtx insn,
+ struct expr *expr)
{
- /* Insert at start of successor block. */
- rtx prev = PREV_INSN (bb->head);
- rtx before = bb->head;
- while (before != 0)
- {
- if (GET_CODE (before) != CODE_LABEL
- && (GET_CODE (before) != NOTE
- || NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK))
- break;
- prev = before;
- if (prev == bb->end)
- break;
- before = NEXT_INSN (before);
- }
-
- insn = emit_insn_after (insn, prev);
+ edge pred;
+ rtx avail_insn = NULL_RTX;
+ rtx avail_reg;
+ rtx dest, pat;
+ struct occr *a_occr;
+ struct unoccr *occr, *avail_occrs = NULL;
+ struct unoccr *unoccr, *unavail_occrs = NULL;
+ int npred_ok = 0;
+ gcov_type ok_count = 0; /* Redundant load execution count. */
+ gcov_type critical_count = 0; /* Execution count of critical edges. */
+
+ /* The execution count of the loads to be added to make the
+ load fully redundant. */
+ gcov_type not_ok_count = 0;
+ basic_block pred_bb;
+
+ pat = PATTERN (insn);
+ dest = SET_DEST (pat);
+ /* Check that the loaded register is not used, set, or killed from the
+ beginning of the block. */
+ if (reg_used_between_after_reload_p (dest,
+ PREV_INSN (BB_HEAD (bb)), insn)
+ || reg_set_between_after_reload_p (dest,
+ PREV_INSN (BB_HEAD (bb)), insn))
+ return;
- if (gcse_file)
+ /* Check potential for replacing load with copy for predecessors. */
+ for (pred = bb->pred; pred; pred = pred->pred_next)
{
- fprintf (gcse_file, "STORE_MOTION insert store at start of BB %d:\n",
- bb->index);
- print_inline_rtx (gcse_file, insn, 6);
- fprintf (gcse_file, "\n");
- }
-}
+ rtx next_pred_bb_end;
-/* This routine will insert a store on an edge. EXPR is the ldst entry for
- the memory reference, and E is the edge to insert it on. Returns nonzero
- if an edge insertion was performed. */
+ avail_insn = NULL_RTX;
+ pred_bb = pred->src;
+ next_pred_bb_end = NEXT_INSN (BB_END (pred_bb));
+ for (a_occr = get_bb_avail_insn (pred_bb, expr->avail_occr); a_occr;
+ a_occr = get_bb_avail_insn (pred_bb, a_occr->next))
+ {
+ /* Check if the loaded register is not used. */
+ avail_insn = a_occr->insn;
+ if (! (avail_reg = get_avail_load_store_reg (avail_insn)))
+ abort ();
+ /* Make sure we can generate a move from register avail_reg to
+ dest. */
+ extract_insn (gen_move_insn (copy_rtx (dest),
+ copy_rtx (avail_reg)));
+ if (! constrain_operands (1)
+ || reg_killed_on_edge (avail_reg, pred)
+ || reg_used_on_edge (dest, pred))
+ {
+ avail_insn = NULL;
+ continue;
+ }
+ if (! reg_set_between_after_reload_p (avail_reg, avail_insn,
+ next_pred_bb_end))
+ /* AVAIL_INSN remains non-null. */
+ break;
+ else
+ avail_insn = NULL;
+ }
+ if (avail_insn != NULL_RTX)
+ {
+ npred_ok++;
+ ok_count += pred->count;
+ if (EDGE_CRITICAL_P (pred))
+ critical_count += pred->count;
+ occr = gmalloc (sizeof (struct unoccr));
+ occr->insn = avail_insn;
+ occr->pred = pred;
+ occr->next = avail_occrs;
+ avail_occrs = occr;
+ }
+ else
+ {
+ not_ok_count += pred->count;
+ if (EDGE_CRITICAL_P (pred))
+ critical_count += pred->count;
+ unoccr = gmalloc (sizeof (struct unoccr));
+ unoccr->insn = NULL_RTX;
+ unoccr->pred = pred;
+ unoccr->next = unavail_occrs;
+ unavail_occrs = unoccr;
+ }
+ }
-static int
-insert_store (expr, e)
- struct ls_expr * expr;
- edge e;
-{
- rtx reg, insn;
- basic_block bb;
- edge tmp;
+ if (npred_ok == 0 /* No load can be replaced by copy. */
+ || (optimize_size && npred_ok > 1)) /* Prevent exploding the code. */
+ goto cleanup;
- /* We did all the deleted before this insert, so if we didn't delete a
- store, then we haven't set the reaching reg yet either. */
- if (expr->reaching_reg == NULL_RTX)
- return 0;
+ /* Check if it's worth applying the partial redundancy elimination. */
+ if (ok_count < GCSE_AFTER_RELOAD_PARTIAL_FRACTION * not_ok_count)
+ goto cleanup;
- reg = expr->reaching_reg;
- insn = gen_move_insn (expr->pattern, reg);
+ if (ok_count < GCSE_AFTER_RELOAD_CRITICAL_FRACTION * critical_count)
+ goto cleanup;
- /* If we are inserting this expression on ALL predecessor edges of a BB,
- insert it at the start of the BB, and reset the insert bits on the other
- edges so we don't try to insert it on the other edges. */
- bb = e->dest;
- for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
+ /* Generate moves to the loaded register from where
+ the memory is available. */
+ for (occr = avail_occrs; occr; occr = occr->next)
{
- int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
- if (index == EDGE_INDEX_NO_EDGE)
+ avail_insn = occr->insn;
+ pred = occr->pred;
+ /* Set avail_reg to be the register having the value of the
+ memory. */
+ avail_reg = get_avail_load_store_reg (avail_insn);
+ if (! avail_reg)
abort ();
- if (! TEST_BIT (pre_insert_map[index], expr->index))
- break;
- }
- /* If tmp is NULL, we found an insertion on every edge, blank the
- insertion vector for these edges, and insert at the start of the BB. */
- if (!tmp && bb != EXIT_BLOCK_PTR)
- {
- for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
- {
- int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
- RESET_BIT (pre_insert_map[index], expr->index);
- }
- insert_insn_start_bb (insn, bb);
- return 0;
+ insert_insn_on_edge (gen_move_insn (copy_rtx (dest),
+ copy_rtx (avail_reg)),
+ pred);
+
+ if (gcse_file)
+ fprintf (gcse_file,
+ "GCSE AFTER reload generating move from %d to %d on \
+ edge from %d to %d\n",
+ REGNO (avail_reg),
+ REGNO (dest),
+ pred->src->index,
+ pred->dest->index);
}
- /* We can't insert on this edge, so we'll insert at the head of the
- successors block. See Morgan, sec 10.5. */
- if ((e->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
+ /* Regenerate loads where the memory is unavailable. */
+ for (unoccr = unavail_occrs; unoccr; unoccr = unoccr->next)
{
- insert_insn_start_bb (insn, bb);
- return 0;
+ pred = unoccr->pred;
+ insert_insn_on_edge (copy_insn (PATTERN (insn)), pred);
+
+ if (gcse_file)
+ fprintf (gcse_file,
+ "GCSE AFTER reload: generating on edge from %d to %d\
+ a copy of load:\n",
+ pred->src->index,
+ pred->dest->index);
}
- insert_insn_on_edge (insn, e);
+ /* Delete the insn if it is not available in this block and mark it
+ for deletion if it is available. If insn is available it may help
+ discover additional redundancies, so mark it for later deletion.*/
+ for (a_occr = get_bb_avail_insn (bb, expr->avail_occr);
+ a_occr && (a_occr->insn != insn);
+ a_occr = get_bb_avail_insn (bb, a_occr->next));
- if (gcse_file)
+ if (!a_occr)
+ delete_insn (insn);
+ else
+ a_occr->deleted_p = 1;
+
+cleanup:
+
+ while (unavail_occrs)
{
- fprintf (gcse_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
- e->src->index, e->dest->index);
- print_inline_rtx (gcse_file, insn, 6);
- fprintf (gcse_file, "\n");
+ struct unoccr *temp = unavail_occrs->next;
+ free (unavail_occrs);
+ unavail_occrs = temp;
}
- return 1;
+ while (avail_occrs)
+ {
+ struct unoccr *temp = avail_occrs->next;
+ free (avail_occrs);
+ avail_occrs = temp;
+ }
}
-/* This routine will replace a store with a SET to a specified register. */
+/* Performing the redundancy elimination as described before. */
static void
-replace_store_insn (reg, del, bb)
- rtx reg, del;
- basic_block bb;
+gcse_after_reload (void)
{
+ unsigned int i;
rtx insn;
+ basic_block bb;
+ struct expr *expr;
+ struct occr *occr;
- insn = gen_move_insn (reg, SET_SRC (PATTERN (del)));
- insn = emit_insn_after (insn, del);
+ /* Note we start at block 1. */
- if (gcse_file)
- {
- fprintf (gcse_file,
- "STORE_MOTION delete insn in BB %d:\n ", bb->index);
- print_inline_rtx (gcse_file, del, 6);
- fprintf (gcse_file, "\nSTORE MOTION replaced with insn:\n ");
- print_inline_rtx (gcse_file, insn, 6);
- fprintf (gcse_file, "\n");
- }
+ if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
+ return;
- delete_insn (del);
-}
+ FOR_BB_BETWEEN (bb,
+ ENTRY_BLOCK_PTR->next_bb->next_bb,
+ EXIT_BLOCK_PTR,
+ next_bb)
+ {
+ if (! bb_has_well_behaved_predecessors (bb))
+ continue;
+ /* Do not try this optimization on cold basic blocks. */
+ if (probably_cold_bb_p (bb))
+ continue;
-/* Delete a store, but copy the value that would have been stored into
- the reaching_reg for later storing. */
+ reset_opr_set_tables ();
-static void
-delete_store (expr, bb)
- struct ls_expr * expr;
- basic_block bb;
-{
- rtx reg, i, del;
+ for (insn = BB_HEAD (bb);
+ insn != NULL
+ && insn != NEXT_INSN (BB_END (bb));
+ insn = NEXT_INSN (insn))
+ {
+ /* Is it a load - of the form (set (reg) (mem))? */
+ if (GET_CODE (insn) == INSN
+ && GET_CODE (PATTERN (insn)) == SET
+ && REG_P (SET_DEST (PATTERN (insn)))
+ && MEM_P (SET_SRC (PATTERN (insn))))
+ {
+ rtx pat = PATTERN (insn);
+ rtx src = SET_SRC (pat);
+ struct expr *expr;
- if (expr->reaching_reg == NULL_RTX)
- expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
+ if (general_operand (src, GET_MODE (src))
+ /* Is the expression recorded? */
+ && (expr = lookup_expr (src, &expr_hash_table)) != NULL
+ /* Are the operands unchanged since the start of the
+ block? */
+ && oprs_not_set_p (src, insn)
+ && ! MEM_VOLATILE_P (src)
+ && GET_MODE (src) != BLKmode
+ && !(flag_non_call_exceptions && may_trap_p (src))
+ && !side_effects_p (src))
+ {
+ /* We now have a load (insn) and an available memory at
+ its BB start (expr). Try to remove the loads if it is
+ redundant. */
+ eliminate_partially_redundant_loads (bb, insn, expr);
+ }
+ }
+ /* Keep track of everything modified by this insn. */
+ if (INSN_P (insn))
+ mark_oprs_set (insn);
+ }
+ }
- /* If there is more than 1 store, the earlier ones will be dead,
- but it doesn't hurt to replace them here. */
- reg = expr->reaching_reg;
+ commit_edge_insertions ();
- for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
+ /* Go over the expression hash table and delete insns that were
+ marked for later deletion. */
+ for (i = 0; i < expr_hash_table.size; i++)
{
- del = XEXP (i, 0);
- if (BLOCK_FOR_INSN (del) == bb)
- {
- /* We know there is only one since we deleted redundant
- ones during the available computation. */
- replace_store_insn (reg, del, bb);
- break;
- }
+ for (expr = expr_hash_table.table[i];
+ expr != NULL;
+ expr = expr->next_same_hash)
+ for (occr = expr->avail_occr; occr; occr = occr->next)
+ if (occr->deleted_p)
+ delete_insn (occr->insn);
}
}
-/* Free memory used by store motion. */
+/* Scan pattern PAT of INSN and add an entry to the hash TABLE.
+ After reload we are interested in loads/stores only. */
static void
-free_store_memory ()
+hash_scan_set_after_reload (rtx pat, rtx insn, struct hash_table *table)
{
- free_ldst_mems ();
+ rtx src = SET_SRC (pat);
+ rtx dest = SET_DEST (pat);
- if (ae_gen)
- sbitmap_vector_free (ae_gen);
- if (ae_kill)
- sbitmap_vector_free (ae_kill);
- if (transp)
- sbitmap_vector_free (transp);
- if (st_antloc)
- sbitmap_vector_free (st_antloc);
- if (pre_insert_map)
- sbitmap_vector_free (pre_insert_map);
- if (pre_delete_map)
- sbitmap_vector_free (pre_delete_map);
- if (reg_set_in_block)
- sbitmap_vector_free (reg_set_in_block);
+ if (! MEM_P (src) && ! MEM_P (dest))
+ return;
- ae_gen = ae_kill = transp = st_antloc = NULL;
- pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
+ if (REG_P (dest))
+ {
+ if (/* Don't GCSE something if we can't do a reg/reg copy. */
+ can_copy_p (GET_MODE (dest))
+ /* GCSE commonly inserts instruction after the insn. We can't
+ do that easily for EH_REGION notes so disable GCSE on these
+ for now. */
+ && ! find_reg_note (insn, REG_EH_REGION, NULL_RTX)
+ /* Is SET_SRC something we want to gcse? */
+ && general_operand (src, GET_MODE (src))
+ /* Don't CSE a nop. */
+ && ! set_noop_p (pat)
+ && ! JUMP_P (insn))
+ {
+ /* An expression is not available if its operands are
+ subsequently modified, including this insn. */
+ if (oprs_available_p (src, insn))
+ insert_expr_in_table (src, GET_MODE (dest), insn, 0, 1, table);
+ }
+ }
+ else if (REG_P (src))
+ {
+ /* Only record sets of pseudo-regs in the hash table. */
+ if (/* Don't GCSE something if we can't do a reg/reg copy. */
+ can_copy_p (GET_MODE (src))
+ /* GCSE commonly inserts instruction after the insn. We can't
+ do that easily for EH_REGION notes so disable GCSE on these
+ for now. */
+ && ! find_reg_note (insn, REG_EH_REGION, NULL_RTX)
+ /* Is SET_DEST something we want to gcse? */
+ && general_operand (dest, GET_MODE (dest))
+ /* Don't CSE a nop. */
+ && ! set_noop_p (pat)
+ &&! JUMP_P (insn)
+ && ! (flag_float_store && FLOAT_MODE_P (GET_MODE (dest)))
+ /* Check if the memory expression is killed after insn. */
+ && ! load_killed_in_block_p (BLOCK_FOR_INSN (insn),
+ INSN_CUID (insn) + 1,
+ dest,
+ 1)
+ && oprs_unchanged_p (XEXP (dest, 0), insn, 1))
+ {
+ insert_expr_in_table (dest, GET_MODE (dest), insn, 0, 1, table);
+ }
+ }
}
-/* Perform store motion. Much like gcse, except we move expressions the
- other way by looking at the flowgraph in reverse. */
+
+/* Create hash table of memory expressions available at end of basic
+ blocks. */
static void
-store_motion ()
+compute_hash_table_after_reload (struct hash_table *table)
{
- basic_block bb;
- int x;
- struct ls_expr * ptr;
- int update_flow = 0;
+ unsigned int i;
- if (gcse_file)
- {
- fprintf (gcse_file, "before store motion\n");
- print_rtl (gcse_file, get_insns ());
- }
+ table->set_p = 0;
+ /* Initialize count of number of entries in hash table. */
+ table->n_elems = 0;
+ memset ((char *) table->table, 0,
+ table->size * sizeof (struct expr *));
- init_alias_analysis ();
+ /* While we compute the hash table we also compute a bit array of which
+ registers are set in which blocks. */
+ sbitmap_vector_zero (reg_set_in_block, last_basic_block);
- /* Find all the stores that are live to the end of their block. */
- num_stores = compute_store_table ();
- if (num_stores == 0)
- {
- sbitmap_vector_free (reg_set_in_block);
- end_alias_analysis ();
- return;
- }
+ /* Re-cache any INSN_LIST nodes we have allocated. */
+ clear_modify_mem_tables ();
- /* Now compute whats actually available to move. */
- add_noreturn_fake_exit_edges ();
- build_store_vectors ();
+ /* Some working arrays used to track first and last set in each block. */
+ reg_avail_info = gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
- edge_list = pre_edge_rev_lcm (gcse_file, num_stores, transp, ae_gen,
- st_antloc, ae_kill, &pre_insert_map,
- &pre_delete_map);
+ for (i = 0; i < max_gcse_regno; ++i)
+ reg_avail_info[i].last_bb = NULL;
- /* Now we want to insert the new stores which are going to be needed. */
- for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
+ FOR_EACH_BB (current_bb)
{
- FOR_EACH_BB (bb)
- if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
- delete_store (ptr, bb);
-
- for (x = 0; x < NUM_EDGES (edge_list); x++)
- if (TEST_BIT (pre_insert_map[x], ptr->index))
- update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
- }
+ rtx insn;
+ unsigned int regno;
- if (update_flow)
- commit_edge_insertions ();
+ /* First pass over the instructions records information used to
+ determine when registers and memory are first and last set. */
+ for (insn = BB_HEAD (current_bb);
+ insn && insn != NEXT_INSN (BB_END (current_bb));
+ insn = NEXT_INSN (insn))
+ {
+ if (! INSN_P (insn))
+ continue;
- free_store_memory ();
- free_edge_list (edge_list);
- remove_fake_edges ();
- end_alias_analysis ();
-}
+ if (CALL_P (insn))
+ {
+ bool clobbers_all = false;
-\f
-/* Entry point for jump bypassing optimization pass. */
+#ifdef NON_SAVING_SETJMP
+ if (NON_SAVING_SETJMP
+ && find_reg_note (insn, REG_SETJMP, NULL_RTX))
+ clobbers_all = true;
+#endif
-int
-bypass_jumps (file)
- FILE *file;
-{
- int changed;
+ for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
+ if (clobbers_all
+ || TEST_HARD_REG_BIT (regs_invalidated_by_call,
+ regno))
+ record_last_reg_set_info (insn, regno);
- /* We do not construct an accurate cfg in functions which call
- setjmp, so just punt to be safe. */
- if (current_function_calls_setjmp)
- return 0;
+ mark_call (insn);
+ }
- /* For calling dump_foo fns from gdb. */
- debug_stderr = stderr;
- gcse_file = file;
+ note_stores (PATTERN (insn), record_last_set_info, insn);
- /* Identify the basic block information for this function, including
- successors and predecessors. */
- max_gcse_regno = max_reg_num ();
+ if (GET_CODE (PATTERN (insn)) == SET)
+ {
+ rtx src, dest;
- if (file)
- dump_flow_info (file);
+ src = SET_SRC (PATTERN (insn));
+ dest = SET_DEST (PATTERN (insn));
+ if (MEM_P (src) && auto_inc_p (XEXP (src, 0)))
+ {
+ regno = REGNO (XEXP (XEXP (src, 0), 0));
+ record_last_reg_set_info (insn, regno);
+ }
+ if (MEM_P (dest) && auto_inc_p (XEXP (dest, 0)))
+ {
+ regno = REGNO (XEXP (XEXP (dest, 0), 0));
+ record_last_reg_set_info (insn, regno);
+ }
+ }
+ }
- /* Return if there's nothing to do. */
- if (n_basic_blocks <= 1)
- return 0;
+ /* The next pass builds the hash table. */
+ for (insn = BB_HEAD (current_bb);
+ insn && insn != NEXT_INSN (BB_END (current_bb));
+ insn = NEXT_INSN (insn))
+ if (INSN_P (insn) && GET_CODE (PATTERN (insn)) == SET)
+ if (! find_reg_note (insn, REG_LIBCALL, NULL_RTX))
+ hash_scan_set_after_reload (PATTERN (insn), insn, table);
+ }
- /* Trying to perform global optimizations on flow graphs which have
- a high connectivity will take a long time and is unlikely to be
- particularly useful.
+ free (reg_avail_info);
+ reg_avail_info = NULL;
+}
- In normal circumstances a cfg should have about twice as many edges
- as blocks. But we do not want to punish small functions which have
- a couple switch statements. So we require a relatively large number
- of basic blocks and the ratio of edges to blocks to be high. */
- if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
- {
- if (warn_disabled_optimization)
- warning ("BYPASS disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
- n_basic_blocks, n_edges / n_basic_blocks);
- return 0;
- }
- /* If allocating memory for the cprop bitmap would take up too much
- storage it's better just to disable the optimization. */
- if ((n_basic_blocks
- * SBITMAP_SET_SIZE (max_gcse_regno)
- * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
- {
- if (warn_disabled_optimization)
- warning ("GCSE disabled: %d basic blocks and %d registers",
- n_basic_blocks, max_gcse_regno);
+/* Main entry point of the GCSE after reload - clean some redundant loads
+ due to spilling. */
- return 0;
- }
+void
+gcse_after_reload_main (rtx f, FILE* file)
+{
+ gcse_subst_count = 0;
+ gcse_create_count = 0;
- /* See what modes support reg/reg copy operations. */
- if (! can_copy_init_p)
- {
- compute_can_copy ();
- can_copy_init_p = 1;
- }
+ gcse_file = file;
gcc_obstack_init (&gcse_obstack);
bytes_used = 0;
/* We need alias. */
init_alias_analysis ();
- /* Record where pseudo-registers are set. This data is kept accurate
- during each pass. ??? We could also record hard-reg information here
- [since it's unchanging], however it is currently done during hash table
- computation.
-
- It may be tempting to compute MEM set information here too, but MEM sets
- will be subject to code motion one day and thus we need to compute
- information about memory sets when we build the hash tables. */
+ max_gcse_regno = max_reg_num ();
alloc_reg_set_mem (max_gcse_regno);
- compute_sets (get_insns ());
+ alloc_gcse_mem (f);
+ alloc_hash_table (max_cuid, &expr_hash_table, 0);
+ compute_hash_table_after_reload (&expr_hash_table);
- max_gcse_regno = max_reg_num ();
- alloc_gcse_mem (get_insns ());
- changed = one_cprop_pass (1, 1, 1);
- free_gcse_mem ();
+ if (gcse_file)
+ dump_hash_table (gcse_file, "Expression", &expr_hash_table);
- if (file)
- {
- fprintf (file, "BYPASS of %s: %d basic blocks, ",
- current_function_name, n_basic_blocks);
- fprintf (file, "%d bytes\n\n", bytes_used);
- }
+ if (expr_hash_table.n_elems > 0)
+ gcse_after_reload ();
- obstack_free (&gcse_obstack, NULL);
+ free_hash_table (&expr_hash_table);
+
+ free_gcse_mem ();
free_reg_set_mem ();
/* We are finished with alias. */
end_alias_analysis ();
- allocate_reg_info (max_reg_num (), FALSE, FALSE);
- return changed;
+ obstack_free (&gcse_obstack, NULL);
}
#include "gt-gcse.h"
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