/* Rewrite a program in Normal form into SSA.
- Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008
+ Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
+the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful,
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to
-the Free Software Foundation, 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "output.h"
-#include "errors.h"
#include "expr.h"
#include "function.h"
#include "diagnostic.h"
#include "cfgloop.h"
#include "domwalk.h"
#include "ggc.h"
+#include "params.h"
+#include "vecprim.h"
/* This file builds the SSA form for a function as described in:
R. Cytron, J. Ferrante, B. Rosen, M. Wegman, and K. Zadeck. Efficiently
Graph. ACM Transactions on Programming Languages and Systems,
13(4):451-490, October 1991. */
-
/* Structure to map a variable VAR to the set of blocks that contain
definitions for VAR. */
struct def_blocks_d
Ith block contains a definition of VAR. */
bitmap def_blocks;
- /* Blocks that contain a phi node for VAR. */
+ /* Blocks that contain a PHI node for VAR. */
bitmap phi_blocks;
/* Blocks where VAR is live-on-entry. Similar semantics as
bitmap livein_blocks;
};
+
/* Each entry in DEF_BLOCKS contains an element of type STRUCT
DEF_BLOCKS_D, mapping a variable VAR to a bitmap describing all the
basic blocks where VAR is defined (assigned a new value). It also
computing PHI pruning heuristics. */
static htab_t def_blocks;
+/* Stack of trees used to restore the global currdefs to its original
+ state after completing rewriting of a block and its dominator
+ children. Its elements have the following properties:
+
+ - An SSA_NAME (N) indicates that the current definition of the
+ underlying variable should be set to the given SSA_NAME. If the
+ symbol associated with the SSA_NAME is not a GIMPLE register, the
+ next slot in the stack must be a _DECL node (SYM). In this case,
+ the name N in the previous slot is the current reaching
+ definition for SYM.
+
+ - A _DECL node indicates that the underlying variable has no
+ current definition.
+
+ - A NULL node at the top entry is used to mark the last slot
+ associated with the current block. */
+static VEC(tree,heap) *block_defs_stack;
+
+/* Set of existing SSA names being replaced by update_ssa. */
+static sbitmap old_ssa_names;
+
+/* Set of new SSA names being added by update_ssa. Note that both
+ NEW_SSA_NAMES and OLD_SSA_NAMES are dense bitmaps because most of
+ the operations done on them are presence tests. */
+static sbitmap new_ssa_names;
+
+/* Symbols whose SSA form needs to be updated or created for the first
+ time. */
+static bitmap syms_to_rename;
+
+/* Subset of SYMS_TO_RENAME. Contains all the GIMPLE register symbols
+ that have been marked for renaming. */
+static bitmap regs_to_rename;
+
+/* Subset of SYMS_TO_RENAME. Contains all the memory symbols
+ that have been marked for renaming. */
+static bitmap mem_syms_to_rename;
+
+/* Set of SSA names that have been marked to be released after they
+ were registered in the replacement table. They will be finally
+ released after we finish updating the SSA web. */
+static bitmap names_to_release;
+
+/* For each block, the PHI nodes that need to be rewritten are stored into
+ these vectors. */
+typedef VEC(tree, heap) *tree_vec;
+DEF_VEC_P (tree_vec);
+DEF_VEC_ALLOC_P (tree_vec, heap);
+
+static VEC(tree_vec, heap) *phis_to_rewrite;
+
+/* The bitmap of non-NULL elements of PHIS_TO_REWRITE. */
+static bitmap blocks_with_phis_to_rewrite;
+
+/* Growth factor for NEW_SSA_NAMES and OLD_SSA_NAMES. These sets need
+ to grow as the callers to register_new_name_mapping will typically
+ create new names on the fly. FIXME. Currently set to 1/3 to avoid
+ frequent reallocations but still need to find a reasonable growth
+ strategy. */
+#define NAME_SETS_GROWTH_FACTOR (MAX (3, num_ssa_names / 3))
+
+/* Tuple used to represent replacement mappings. */
+struct repl_map_d
+{
+ tree name;
+ bitmap set;
+};
+
+/* NEW -> OLD_SET replacement table. If we are replacing several
+ existing SSA names O_1, O_2, ..., O_j with a new name N_i,
+ then REPL_TBL[N_i] = { O_1, O_2, ..., O_j }. */
+static htab_t repl_tbl;
+
+/* true if register_new_name_mapping needs to initialize the data
+ structures needed by update_ssa. */
+static bool need_to_initialize_update_ssa_p = true;
+
+/* true if update_ssa needs to update virtual operands. */
+static bool need_to_update_vops_p = false;
+
+/* Statistics kept by update_ssa to use in the virtual mapping
+ heuristic. If the number of virtual mappings is beyond certain
+ threshold, the updater will switch from using the mappings into
+ renaming the virtual symbols from scratch. In some cases, the
+ large number of name mappings for virtual names causes significant
+ slowdowns in the PHI insertion code. */
+struct update_ssa_stats_d
+{
+ unsigned num_virtual_mappings;
+ unsigned num_total_mappings;
+ bitmap virtual_symbols;
+ unsigned num_virtual_symbols;
+};
+static struct update_ssa_stats_d update_ssa_stats;
+
/* Global data to attach to the main dominator walk structure. */
struct mark_def_sites_global_data
{
- /* This sbitmap contains the variables which are set before they
- are used in a basic block. We keep it as a global variable
- solely to avoid the overhead of allocating and deallocating
- the bitmap. */
- sbitmap kills;
+ /* This bitmap contains the variables which are set before they
+ are used in a basic block. */
+ bitmap kills;
/* Bitmap of names to rename. */
sbitmap names_to_rename;
-};
-struct rewrite_block_data
-{
- varray_type block_defs;
+ /* Set of blocks that mark_def_sites deems interesting for the
+ renamer to process. */
+ sbitmap interesting_blocks;
};
-/* Information stored for ssa names. */
+/* Information stored for SSA names. */
struct ssa_name_info
{
+ /* The current reaching definition replacing this SSA name. */
+ tree current_def;
+
/* This field indicates whether or not the variable may need PHI nodes.
See the enum's definition for more detailed information about the
states. */
ENUM_BITFIELD (need_phi_state) need_phi_state : 2;
- /* The actual definition of the ssa name. */
- tree current_def;
+ /* Age of this record (so that info_for_ssa_name table can be cleared
+ quickly); if AGE < CURRENT_INFO_FOR_SSA_NAME_AGE, then the fields
+ are assumed to be null. */
+ unsigned age;
+};
+
+/* The information associated with names. */
+typedef struct ssa_name_info *ssa_name_info_p;
+DEF_VEC_P (ssa_name_info_p);
+DEF_VEC_ALLOC_P (ssa_name_info_p, heap);
+
+static VEC(ssa_name_info_p, heap) *info_for_ssa_name;
+static unsigned current_info_for_ssa_name_age;
+
+/* The set of blocks affected by update_ssa. */
+static bitmap blocks_to_update;
+
+/* The main entry point to the SSA renamer (rewrite_blocks) may be
+ called several times to do different, but related, tasks.
+ Initially, we need it to rename the whole program into SSA form.
+ At other times, we may need it to only rename into SSA newly
+ exposed symbols. Finally, we can also call it to incrementally fix
+ an already built SSA web. */
+enum rewrite_mode {
+ /* Convert the whole function into SSA form. */
+ REWRITE_ALL,
+
+ /* Incrementally update the SSA web by replacing existing SSA
+ names with new ones. See update_ssa for details. */
+ REWRITE_UPDATE
};
-/* Local functions. */
-static void rewrite_finalize_block (struct dom_walk_data *, basic_block);
-static void rewrite_initialize_block_local_data (struct dom_walk_data *,
- basic_block, bool);
-static void rewrite_initialize_block (struct dom_walk_data *, basic_block);
-static void rewrite_add_phi_arguments (struct dom_walk_data *, basic_block);
-static void mark_def_sites (struct dom_walk_data *walk_data,
- basic_block bb, block_stmt_iterator);
-static void mark_def_sites_initialize_block (struct dom_walk_data *walk_data,
- basic_block bb);
-static void set_def_block (tree, basic_block, bool, bool);
-static void set_livein_block (tree, basic_block);
-static bool prepare_use_operand_for_rename (use_operand_p, size_t *uid_p);
-static bool prepare_def_operand_for_rename (tree def, size_t *uid_p);
-static void insert_phi_nodes (bitmap *, bitmap);
-static void rewrite_stmt (struct dom_walk_data *, basic_block,
- block_stmt_iterator);
-static inline void rewrite_operand (use_operand_p);
-static void insert_phi_nodes_for (tree, bitmap *, varray_type *);
-static tree get_reaching_def (tree);
-static hashval_t def_blocks_hash (const void *);
-static int def_blocks_eq (const void *, const void *);
-static void def_blocks_free (void *);
-static int debug_def_blocks_r (void **, void *);
-static inline struct def_blocks_d *get_def_blocks_for (tree);
-static inline struct def_blocks_d *find_def_blocks_for (tree);
-static void htab_statistics (FILE *, htab_t);
+
+/* Use TREE_VISITED to keep track of which statements we want to
+ rename. When renaming a subset of the variables, not all
+ statements will be processed. This is decided in mark_def_sites. */
+#define REWRITE_THIS_STMT(T) TREE_VISITED (T)
+
+/* Use the unsigned flag to keep track of which statements we want to
+ visit when marking new definition sites. This is slightly
+ different than REWRITE_THIS_STMT: it's used by update_ssa to
+ distinguish statements that need to have both uses and defs
+ processed from those that only need to have their defs processed.
+ Statements that define new SSA names only need to have their defs
+ registered, but they don't need to have their uses renamed. */
+#define REGISTER_DEFS_IN_THIS_STMT(T) (T)->base.unsigned_flag
+
+
+/* Prototypes for debugging functions. */
+extern void dump_tree_ssa (FILE *);
+extern void debug_tree_ssa (void);
+extern void debug_def_blocks (void);
+extern void dump_tree_ssa_stats (FILE *);
+extern void debug_tree_ssa_stats (void);
+extern void dump_update_ssa (FILE *);
+extern void debug_update_ssa (void);
+extern void dump_names_replaced_by (FILE *, tree);
+extern void debug_names_replaced_by (tree);
+extern void dump_def_blocks (FILE *);
+extern void debug_def_blocks (void);
+extern void dump_defs_stack (FILE *, int);
+extern void debug_defs_stack (int);
+extern void dump_currdefs (FILE *);
+extern void debug_currdefs (void);
/* Get the information associated with NAME. */
-static inline struct ssa_name_info *
+static inline ssa_name_info_p
get_ssa_name_ann (tree name)
{
- if (!SSA_NAME_AUX (name))
- SSA_NAME_AUX (name) = xcalloc (1, sizeof (struct ssa_name_info));
+ unsigned ver = SSA_NAME_VERSION (name);
+ unsigned len = VEC_length (ssa_name_info_p, info_for_ssa_name);
+ struct ssa_name_info *info;
+
+ if (ver >= len)
+ {
+ unsigned new_len = num_ssa_names;
+
+ VEC_reserve (ssa_name_info_p, heap, info_for_ssa_name, new_len);
+ while (len++ < new_len)
+ {
+ struct ssa_name_info *info = XCNEW (struct ssa_name_info);
+ info->age = current_info_for_ssa_name_age;
+ VEC_quick_push (ssa_name_info_p, info_for_ssa_name, info);
+ }
+ }
+
+ info = VEC_index (ssa_name_info_p, info_for_ssa_name, ver);
+ if (info->age < current_info_for_ssa_name_age)
+ {
+ info->need_phi_state = 0;
+ info->current_def = NULL_TREE;
+ info->age = current_info_for_ssa_name_age;
+ }
+
+ return info;
+}
- return SSA_NAME_AUX (name);
+
+/* Clears info for SSA names. */
+
+static void
+clear_ssa_name_info (void)
+{
+ current_info_for_ssa_name_age++;
}
-/* Gets phi_state field for VAR. */
+
+/* Get phi_state field for VAR. */
static inline enum need_phi_state
get_phi_state (tree var)
return var_ann (var)->need_phi_state;
}
+
/* Sets phi_state field for VAR to STATE. */
static inline void
var_ann (var)->need_phi_state = state;
}
+
/* Return the current definition for VAR. */
-static inline tree
+tree
get_current_def (tree var)
{
if (TREE_CODE (var) == SSA_NAME)
return var_ann (var)->current_def;
}
+
/* Sets current definition of VAR to DEF. */
-static inline void
+void
set_current_def (tree var, tree def)
{
if (TREE_CODE (var) == SSA_NAME)
var_ann (var)->current_def = def;
}
-/* Compute global livein information given the set of blockx where
+
+/* Compute global livein information given the set of blocks where
an object is locally live at the start of the block (LIVEIN)
and the set of blocks where the object is defined (DEF_BLOCKS).
compute_global_livein (bitmap livein, bitmap def_blocks)
{
basic_block bb, *worklist, *tos;
- int i;
+ unsigned i;
+ bitmap_iterator bi;
tos = worklist
- = (basic_block *) xmalloc (sizeof (basic_block) * (n_basic_blocks + 1));
+ = (basic_block *) xmalloc (sizeof (basic_block) * (last_basic_block + 1));
- EXECUTE_IF_SET_IN_BITMAP (livein, 0, i,
- {
- *tos++ = BASIC_BLOCK (i);
- });
+ EXECUTE_IF_SET_IN_BITMAP (livein, 0, i, bi)
+ *tos++ = BASIC_BLOCK (i);
/* Iterate until the worklist is empty. */
while (tos != worklist)
{
edge e;
+ edge_iterator ei;
/* Pull a block off the worklist. */
bb = *--tos;
/* For each predecessor block. */
- for (e = bb->pred; e; e = e->pred_next)
+ FOR_EACH_EDGE (e, ei, bb->preds)
{
basic_block pred = e->src;
int pred_index = pred->index;
}
-/* Block initialization routine for mark_def_sites. Clear the
- KILLS bitmap at the start of each block. */
-
-static void
-mark_def_sites_initialize_block (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED)
-{
- struct mark_def_sites_global_data *gd = walk_data->global_data;
- sbitmap kills = gd->kills;
-
- sbitmap_zero (kills);
-}
-
-/* Block initialization routine for mark_def_sites. Clear the
- KILLS bitmap at the start of each block. */
+/* Cleans up the REWRITE_THIS_STMT and REGISTER_DEFS_IN_THIS_STMT flags for
+ all statements in basic block BB. */
static void
-ssa_mark_def_sites_initialize_block (struct dom_walk_data *walk_data,
- basic_block bb)
+initialize_flags_in_bb (basic_block bb)
{
- struct mark_def_sites_global_data *gd = walk_data->global_data;
- sbitmap kills = gd->kills;
- tree phi, def;
- unsigned def_uid;
+ tree phi, stmt;
+ block_stmt_iterator bsi;
- sbitmap_zero (kills);
-
- for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
{
- def = PHI_RESULT (phi);
- def_uid = SSA_NAME_VERSION (def);
-
- if (!TEST_BIT (gd->names_to_rename, def_uid))
- continue;
-
- set_def_block (def, bb, true, true);
- SET_BIT (kills, def_uid);
+ REWRITE_THIS_STMT (phi) = 0;
+ REGISTER_DEFS_IN_THIS_STMT (phi) = 0;
}
-}
-
-/* Marks ssa names used as arguments of phis at the end of BB. */
-
-static void
-ssa_mark_phi_uses (struct dom_walk_data *walk_data, basic_block bb)
-{
- struct mark_def_sites_global_data *gd = walk_data->global_data;
- sbitmap kills = gd->kills;
- edge e;
- tree phi, use;
- unsigned uid;
- for (e = bb->succ; e; e = e->succ_next)
+ for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
{
- if (e->dest == EXIT_BLOCK_PTR)
- continue;
-
- for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
- {
- use = PHI_ARG_DEF_FROM_EDGE (phi, e);
- if (TREE_CODE (use) != SSA_NAME)
- continue;
-
- uid = SSA_NAME_VERSION (use);
-
- if (TEST_BIT (gd->names_to_rename, uid)
- && !TEST_BIT (kills, uid))
- set_livein_block (use, bb);
- }
+ stmt = bsi_stmt (bsi);
+ /* We are going to use the operand cache API, such as
+ SET_USE, SET_DEF, and FOR_EACH_IMM_USE_FAST. The operand
+ cache for each statement should be up-to-date. */
+ gcc_assert (!stmt_modified_p (stmt));
+ REWRITE_THIS_STMT (stmt) = 0;
+ REGISTER_DEFS_IN_THIS_STMT (stmt) = 0;
}
}
-/* Call back for walk_dominator_tree used to collect definition sites
- for every variable in the function. For every statement S in block
- BB:
-
- 1- Variables defined by S in DEF_OPS(S) are marked in the bitmap
- WALK_DATA->GLOBAL_DATA->KILLS.
-
- 2- If S uses a variable VAR and there is no preceding kill of VAR,
- then it is marked in marked in the LIVEIN_BLOCKS bitmap
- associated with VAR.
-
- This information is used to determine which variables are live
- across block boundaries to reduce the number of PHI nodes
- we create. */
+/* Mark block BB as interesting for update_ssa. */
static void
-mark_def_sites (struct dom_walk_data *walk_data,
- basic_block bb,
- block_stmt_iterator bsi)
+mark_block_for_update (basic_block bb)
{
- struct mark_def_sites_global_data *gd = walk_data->global_data;
- sbitmap kills = gd->kills;
- size_t uid;
- tree stmt, def;
- use_operand_p use_p;
- def_operand_p def_p;
- ssa_op_iter iter;
-
- /* Mark all the blocks that have definitions for each variable in the
- VARS_TO_RENAME bitmap. */
- stmt = bsi_stmt (bsi);
- get_stmt_operands (stmt);
-
- /* If a variable is used before being set, then the variable is live
- across a block boundary, so mark it live-on-entry to BB. */
-
- FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
- {
- if (prepare_use_operand_for_rename (use_p, &uid)
- && !TEST_BIT (kills, uid))
- set_livein_block (USE_FROM_PTR (use_p), bb);
- }
-
- /* Note that virtual definitions are irrelevant for computing KILLS
- because a V_MAY_DEF does not constitute a killing definition of the
- variable. However, the operand of a virtual definitions is a use
- of the variable, so it may cause the variable to be considered
- live-on-entry. */
-
- FOR_EACH_SSA_MAYDEF_OPERAND (def_p, use_p, stmt, iter)
- {
- if (prepare_use_operand_for_rename (use_p, &uid))
- {
- /* If we do not already have an SSA_NAME for our destination,
- then set the destination to the source. */
- if (TREE_CODE (DEF_FROM_PTR (def_p)) != SSA_NAME)
- SET_DEF (def_p, USE_FROM_PTR (use_p));
-
- set_livein_block (USE_FROM_PTR (use_p), bb);
- set_def_block (DEF_FROM_PTR (def_p), bb, false, false);
- }
- }
-
- /* Now process the virtual must-defs made by this statement. */
- FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF | SSA_OP_VMUSTDEF)
- {
- if (prepare_def_operand_for_rename (def, &uid))
- {
- set_def_block (def, bb, false, false);
- SET_BIT (kills, uid);
- }
- }
-
+ gcc_assert (blocks_to_update != NULL);
+ if (bitmap_bit_p (blocks_to_update, bb->index))
+ return;
+ bitmap_set_bit (blocks_to_update, bb->index);
+ initialize_flags_in_bb (bb);
}
-/* Ditto, but works over ssa names. */
-
-static void
-ssa_mark_def_sites (struct dom_walk_data *walk_data,
- basic_block bb,
- block_stmt_iterator bsi)
-{
- struct mark_def_sites_global_data *gd = walk_data->global_data;
- sbitmap kills = gd->kills;
- size_t uid, def_uid;
- tree stmt, use, def;
- ssa_op_iter iter;
+/* Return the set of blocks where variable VAR is defined and the blocks
+ where VAR is live on entry (livein). If no entry is found in
+ DEF_BLOCKS, a new one is created and returned. */
- /* Mark all the blocks that have definitions for each variable in the
- names_to_rename bitmap. */
- stmt = bsi_stmt (bsi);
- get_stmt_operands (stmt);
+static inline struct def_blocks_d *
+get_def_blocks_for (tree var)
+{
+ struct def_blocks_d db, *db_p;
+ void **slot;
- /* If a variable is used before being set, then the variable is live
- across a block boundary, so mark it live-on-entry to BB. */
- FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_ALL_USES)
+ db.var = var;
+ slot = htab_find_slot (def_blocks, (void *) &db, INSERT);
+ if (*slot == NULL)
{
- uid = SSA_NAME_VERSION (use);
-
- if (TEST_BIT (gd->names_to_rename, uid)
- && !TEST_BIT (kills, uid))
- set_livein_block (use, bb);
+ db_p = XNEW (struct def_blocks_d);
+ db_p->var = var;
+ db_p->def_blocks = BITMAP_ALLOC (NULL);
+ db_p->phi_blocks = BITMAP_ALLOC (NULL);
+ db_p->livein_blocks = BITMAP_ALLOC (NULL);
+ *slot = (void *) db_p;
}
-
- /* Now process the definition made by this statement. Mark the
- variables in KILLS. */
- FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
- {
- def_uid = SSA_NAME_VERSION (def);
+ else
+ db_p = (struct def_blocks_d *) *slot;
- if (TEST_BIT (gd->names_to_rename, def_uid))
- {
- set_def_block (def, bb, false, true);
- SET_BIT (kills, def_uid);
- }
- }
+ return db_p;
}
+
/* Mark block BB as the definition site for variable VAR. PHI_P is true if
- VAR is defined by a phi node. SSA_P is true if we are called from
- rewrite_ssa_into_ssa. */
+ VAR is defined by a PHI node. */
static void
-set_def_block (tree var, basic_block bb, bool phi_p, bool ssa_p)
+set_def_block (tree var, basic_block bb, bool phi_p)
{
struct def_blocks_d *db_p;
enum need_phi_state state;
- if (!ssa_p
- && TREE_CODE (var) == SSA_NAME)
- var = SSA_NAME_VAR (var);
-
state = get_phi_state (var);
db_p = get_def_blocks_for (var);
if (phi_p)
bitmap_set_bit (db_p->phi_blocks, bb->index);
- /* Keep track of whether or not we may need to insert phi nodes.
+ /* Keep track of whether or not we may need to insert PHI nodes.
If we are in the UNKNOWN state, then this is the first definition
of VAR. Additionally, we have not seen any uses of VAR yet, so
- we do not need a phi node for this variable at this time (i.e.,
+ we do not need a PHI node for this variable at this time (i.e.,
transition to NEED_PHI_STATE_NO).
If we are in any other state, then we either have multiple definitions
/* Set the bit corresponding to the block where VAR is live in. */
bitmap_set_bit (db_p->livein_blocks, bb->index);
- /* Keep track of whether or not we may need to insert phi nodes.
+ /* Keep track of whether or not we may need to insert PHI nodes.
If we reach here in NEED_PHI_STATE_NO, see if this use is dominated
by the single block containing the definition(s) of this variable. If
}
-/* If the use operand pointed to by OP_P needs to be renamed, then strip away
- any SSA_NAME wrapping the operand, set *UID_P to the underlying variable's
- uid, and return true. Otherwise return false. If the operand was an
- SSA_NAME, change it to the stripped name. */
+/* Return true if symbol SYM is marked for renaming. */
-static bool
-prepare_use_operand_for_rename (use_operand_p op_p, size_t *uid_p)
+static inline bool
+symbol_marked_for_renaming (tree sym)
{
- tree use = USE_FROM_PTR (op_p);
- tree var = (TREE_CODE (use) != SSA_NAME) ? use : SSA_NAME_VAR (use);
- *uid_p = var_ann (var)->uid;
-
- /* Ignore variables that don't need to be renamed. */
- if (vars_to_rename && !bitmap_bit_p (vars_to_rename, *uid_p))
- return false;
+ return bitmap_bit_p (syms_to_rename, DECL_UID (sym));
+}
- /* The variable needs to be renamed. If this is a use which already
- has an SSA_NAME, then strip it off.
- By not throwing away SSA_NAMEs on assignments, we avoid a lot of
- useless churn of SSA_NAMEs without having to overly complicate the
- renamer. */
- if (TREE_CODE (use) == SSA_NAME)
- SET_USE (op_p, var);
+/* Return true if NAME is in OLD_SSA_NAMES. */
- return true;
+static inline bool
+is_old_name (tree name)
+{
+ unsigned ver = SSA_NAME_VERSION (name);
+ return ver < new_ssa_names->n_bits && TEST_BIT (old_ssa_names, ver);
}
-/* If the def variable DEF needs to be renamed, then strip away any SSA_NAME
- wrapping the operand, set *UID_P to the underlying variable's uid and return
- true. Otherwise return false. */
-static bool
-prepare_def_operand_for_rename (tree def, size_t *uid_p)
-{
- tree var = (TREE_CODE (def) != SSA_NAME) ? def : SSA_NAME_VAR (def);
- *uid_p = var_ann (var)->uid;
-
- /* Ignore variables that don't need to be renamed. */
- if (vars_to_rename && !bitmap_bit_p (vars_to_rename, *uid_p))
- return false;
+/* Return true if NAME is in NEW_SSA_NAMES. */
- return true;
+static inline bool
+is_new_name (tree name)
+{
+ unsigned ver = SSA_NAME_VERSION (name);
+ return ver < new_ssa_names->n_bits && TEST_BIT (new_ssa_names, ver);
}
-/* Helper for insert_phi_nodes. If VAR needs PHI nodes, insert them
- at the dominance frontier (DFS) of blocks defining VAR.
- WORK_STACK is the varray used to implement the worklist of basic
- blocks. */
-static inline
-void insert_phi_nodes_1 (tree var, bitmap *dfs, varray_type *work_stack)
+/* Hashing and equality functions for REPL_TBL. */
+
+static hashval_t
+repl_map_hash (const void *p)
{
- if (get_phi_state (var) != NEED_PHI_STATE_NO)
- insert_phi_nodes_for (var, dfs, work_stack);
+ return htab_hash_pointer ((const void *)((const struct repl_map_d *)p)->name);
}
-/* Insert PHI nodes at the dominance frontier of blocks with variable
- definitions. DFS contains the dominance frontier information for
- the flowgraph. PHI nodes will only be inserted at the dominance
- frontier of definition blocks for variables whose NEED_PHI_STATE
- annotation is marked as ``maybe'' or ``unknown'' (computed by
- mark_def_sites). If NAMES_TO_RENAME is not NULL, do the same but
- for ssa name rewriting. */
+static int
+repl_map_eq (const void *p1, const void *p2)
+{
+ return ((const struct repl_map_d *)p1)->name
+ == ((const struct repl_map_d *)p2)->name;
+}
static void
-insert_phi_nodes (bitmap *dfs, bitmap names_to_rename)
+repl_map_free (void *p)
{
- size_t i;
- varray_type work_stack;
-
- timevar_push (TV_TREE_INSERT_PHI_NODES);
-
- /* Array WORK_STACK is a stack of CFG blocks. Each block that contains
- an assignment or PHI node will be pushed to this stack. */
- VARRAY_GENERIC_PTR_NOGC_INIT (work_stack, last_basic_block, "work_stack");
+ BITMAP_FREE (((struct repl_map_d *)p)->set);
+ free (p);
+}
- /* Iterate over all variables in VARS_TO_RENAME. For each variable, add
- to the work list all the blocks that have a definition for the
- variable. PHI nodes will be added to the dominance frontier blocks of
- each definition block. */
- if (names_to_rename)
- {
- EXECUTE_IF_SET_IN_BITMAP (names_to_rename, 0, i,
- {
- if (ssa_name (i))
- insert_phi_nodes_1 (ssa_name (i), dfs, &work_stack);
- });
- }
- else if (vars_to_rename)
- EXECUTE_IF_SET_IN_BITMAP (vars_to_rename, 0, i,
- insert_phi_nodes_1 (referenced_var (i), dfs, &work_stack));
- else
- for (i = 0; i < num_referenced_vars; i++)
- insert_phi_nodes_1 (referenced_var (i), dfs, &work_stack);
- VARRAY_FREE (work_stack);
+/* Return the names replaced by NEW (i.e., REPL_TBL[NEW].SET). */
- timevar_pop (TV_TREE_INSERT_PHI_NODES);
-}
+static inline bitmap
+names_replaced_by (tree new)
+{
+ struct repl_map_d m;
+ void **slot;
+ m.name = new;
+ slot = htab_find_slot (repl_tbl, (void *) &m, NO_INSERT);
-/* Perform a depth-first traversal of the dominator tree looking for
- variables to rename. BB is the block where to start searching.
- Renaming is a five step process:
+ /* If N was not registered in the replacement table, return NULL. */
+ if (slot == NULL || *slot == NULL)
+ return NULL;
- 1- Every definition made by PHI nodes at the start of the blocks is
- registered as the current definition for the corresponding variable.
+ return ((struct repl_map_d *) *slot)->set;
+}
- 2- Every statement in BB is rewritten. USE and VUSE operands are
- rewritten with their corresponding reaching definition. DEF and
- VDEF targets are registered as new definitions.
-
- 3- All the PHI nodes in successor blocks of BB are visited. The
- argument corresponding to BB is replaced with its current reaching
- definition.
- 4- Recursively rewrite every dominator child block of BB.
+/* Add OLD to REPL_TBL[NEW].SET. */
- 5- Restore (in reverse order) the current reaching definition for every
- new definition introduced in this block. This is done so that when
- we return from the recursive call, all the current reaching
- definitions are restored to the names that were valid in the
- dominator parent of BB. */
+static inline void
+add_to_repl_tbl (tree new, tree old)
+{
+ struct repl_map_d m, *mp;
+ void **slot;
-/* Initialize the local stacks.
-
- BLOCK_DEFS is used to save all the existing reaching definitions for
- the new SSA names introduced in this block. Before registering a
- new definition for a variable, the existing reaching definition is
- pushed into this stack so that we can restore it in Step 5. */
+ m.name = new;
+ slot = htab_find_slot (repl_tbl, (void *) &m, INSERT);
+ if (*slot == NULL)
+ {
+ mp = XNEW (struct repl_map_d);
+ mp->name = new;
+ mp->set = BITMAP_ALLOC (NULL);
+ *slot = (void *) mp;
+ }
+ else
+ mp = (struct repl_map_d *) *slot;
-static void
-rewrite_initialize_block_local_data (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
- basic_block bb ATTRIBUTE_UNUSED,
- bool recycled ATTRIBUTE_UNUSED)
-{
- struct rewrite_block_data *bd
- = (struct rewrite_block_data *)VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
-
- /* We get cleared memory from the allocator, so if the memory is
- not cleared, then we are re-using a previously allocated entry. In
- that case, we can also re-use the underlying virtual arrays. Just
- make sure we clear them before using them! */
- gcc_assert (!recycled || !bd->block_defs || !(VARRAY_ACTIVE_SIZE (bd->block_defs) > 0));
+ bitmap_set_bit (mp->set, SSA_NAME_VERSION (old));
}
-/* SSA Rewriting Step 1. Initialization, create a block local stack
- of reaching definitions for new SSA names produced in this block
- (BLOCK_DEFS). Register new definitions for every PHI node in the
- block. */
+/* Add a new mapping NEW -> OLD REPL_TBL. Every entry N_i in REPL_TBL
+ represents the set of names O_1 ... O_j replaced by N_i. This is
+ used by update_ssa and its helpers to introduce new SSA names in an
+ already formed SSA web. */
static void
-rewrite_initialize_block (struct dom_walk_data *walk_data, basic_block bb)
+add_new_name_mapping (tree new, tree old)
{
- tree phi;
- struct rewrite_block_data *bd
- = (struct rewrite_block_data *)VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
+ timevar_push (TV_TREE_SSA_INCREMENTAL);
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "\n\nRenaming block #%d\n\n", bb->index);
+ /* OLD and NEW must be different SSA names for the same symbol. */
+ gcc_assert (new != old && SSA_NAME_VAR (new) == SSA_NAME_VAR (old));
- /* Step 1. Register new definitions for every PHI node in the block.
- Conceptually, all the PHI nodes are executed in parallel and each PHI
- node introduces a new version for the associated variable. */
- for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ /* If this mapping is for virtual names, we will need to update
+ virtual operands. If this is a mapping for .MEM, then we gather
+ the symbols associated with each name. */
+ if (!is_gimple_reg (new))
{
- tree result = PHI_RESULT (phi);
+ tree sym;
- register_new_def (result, &bd->block_defs);
- }
-}
+ need_to_update_vops_p = true;
-/* Register DEF (an SSA_NAME) to be a new definition for the original
- ssa name VAR and push VAR's current reaching definition
- into the stack pointed by BLOCK_DEFS_P. */
+ update_ssa_stats.num_virtual_mappings++;
+ update_ssa_stats.num_virtual_symbols++;
-static void
-ssa_register_new_def (tree var, tree def, varray_type *block_defs_p)
-{
- tree currdef;
-
- /* If this variable is set in a single basic block and all uses are
- dominated by the set(s) in that single basic block, then there is
- nothing to do. TODO we should not be called at all, and just
- keep the original name. */
- if (get_phi_state (var) == NEED_PHI_STATE_NO)
+ /* Keep counts of virtual mappings and symbols to use in the
+ virtual mapping heuristic. If we have large numbers of
+ virtual mappings for a relatively low number of symbols, it
+ will make more sense to rename the symbols from scratch.
+ Otherwise, the insertion of PHI nodes for each of the old
+ names in these mappings will be very slow. */
+ sym = SSA_NAME_VAR (new);
+ bitmap_set_bit (update_ssa_stats.virtual_symbols, DECL_UID (sym));
+ }
+
+ /* We may need to grow NEW_SSA_NAMES and OLD_SSA_NAMES because our
+ caller may have created new names since the set was created. */
+ if (new_ssa_names->n_bits <= num_ssa_names - 1)
{
- set_current_def (var, def);
- return;
+ unsigned int new_sz = num_ssa_names + NAME_SETS_GROWTH_FACTOR;
+ new_ssa_names = sbitmap_resize (new_ssa_names, new_sz, 0);
+ old_ssa_names = sbitmap_resize (old_ssa_names, new_sz, 0);
}
- currdef = get_current_def (var);
- if (! *block_defs_p)
- VARRAY_TREE_INIT (*block_defs_p, 20, "block_defs");
+ /* Update the REPL_TBL table. */
+ add_to_repl_tbl (new, old);
+
+ /* If OLD had already been registered as a new name, then all the
+ names that OLD replaces should also be replaced by NEW. */
+ if (is_new_name (old))
+ bitmap_ior_into (names_replaced_by (new), names_replaced_by (old));
+
+ /* Register NEW and OLD in NEW_SSA_NAMES and OLD_SSA_NAMES,
+ respectively. */
+ SET_BIT (new_ssa_names, SSA_NAME_VERSION (new));
+ SET_BIT (old_ssa_names, SSA_NAME_VERSION (old));
- /* Push the current reaching definition into *BLOCK_DEFS_P. This stack is
- later used by the dominator tree callbacks to restore the reaching
- definitions for all the variables defined in the block after a recursive
- visit to all its immediately dominated blocks. */
- VARRAY_PUSH_TREE (*block_defs_p, var);
- VARRAY_PUSH_TREE (*block_defs_p, currdef);
+ /* Update mapping counter to use in the virtual mapping heuristic. */
+ update_ssa_stats.num_total_mappings++;
- /* Set the current reaching definition for VAR to be DEF. */
- set_current_def (var, def);
+ timevar_pop (TV_TREE_SSA_INCREMENTAL);
}
-/* Ditto, for rewriting ssa names. */
-static void
-ssa_rewrite_initialize_block (struct dom_walk_data *walk_data, basic_block bb)
-{
- tree phi, new_name;
- struct rewrite_block_data *bd
- = (struct rewrite_block_data *)VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
- sbitmap names_to_rename = walk_data->global_data;
- edge e;
- bool abnormal_phi;
+/* Call back for walk_dominator_tree used to collect definition sites
+ for every variable in the function. For every statement S in block
+ BB:
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "\n\nRenaming block #%d\n\n", bb->index);
+ 1- Variables defined by S in the DEFS of S are marked in the bitmap
+ WALK_DATA->GLOBAL_DATA->KILLS.
- for (e = bb->pred; e; e = e->pred_next)
- if (e->flags & EDGE_ABNORMAL)
- break;
- abnormal_phi = (e != NULL);
+ 2- If S uses a variable VAR and there is no preceding kill of VAR,
+ then it is marked in the LIVEIN_BLOCKS bitmap associated with VAR.
- /* Step 1. Register new definitions for every PHI node in the block.
- Conceptually, all the PHI nodes are executed in parallel and each PHI
- node introduces a new version for the associated variable. */
- for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
- {
- tree result = PHI_RESULT (phi);
+ This information is used to determine which variables are live
+ across block boundaries to reduce the number of PHI nodes
+ we create. */
- if (TEST_BIT (names_to_rename, SSA_NAME_VERSION (result)))
- {
- new_name = duplicate_ssa_name (result, phi);
- SET_PHI_RESULT (phi, new_name);
+static void
+mark_def_sites (struct dom_walk_data *walk_data, basic_block bb,
+ block_stmt_iterator bsi)
+{
+ struct mark_def_sites_global_data *gd;
+ bitmap kills;
+ tree stmt, def;
+ use_operand_p use_p;
+ ssa_op_iter iter;
- if (abnormal_phi)
- SSA_NAME_OCCURS_IN_ABNORMAL_PHI (new_name) = 1;
- }
- else
- new_name = result;
+ stmt = bsi_stmt (bsi);
+ update_stmt_if_modified (stmt);
- ssa_register_new_def (result, new_name, &bd->block_defs);
- }
-}
+ gd = (struct mark_def_sites_global_data *) walk_data->global_data;
+ kills = gd->kills;
-/* SSA Rewriting Step 3. Visit all the successor blocks of BB looking for
- PHI nodes. For every PHI node found, add a new argument containing the
- current reaching definition for the variable and the edge through which
- that definition is reaching the PHI node. */
-
-static void
-rewrite_add_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
- basic_block bb)
-{
- edge e;
+ gcc_assert (blocks_to_update == NULL);
+ REGISTER_DEFS_IN_THIS_STMT (stmt) = 0;
+ REWRITE_THIS_STMT (stmt) = 0;
- for (e = bb->succ; e; e = e->succ_next)
+ /* If a variable is used before being set, then the variable is live
+ across a block boundary, so mark it live-on-entry to BB. */
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
{
- tree phi;
-
- for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
- {
- tree currdef;
-
- /* If this PHI node has already been rewritten, then there is
- nothing to do for this PHI or any following PHIs since we
- always add new PHI nodes at the start of the PHI chain. */
- if (PHI_REWRITTEN (phi))
- break;
-
- currdef = get_reaching_def (SSA_NAME_VAR (PHI_RESULT (phi)));
- add_phi_arg (&phi, currdef, e);
- }
+ tree sym = USE_FROM_PTR (use_p);
+ gcc_assert (DECL_P (sym));
+ if (!bitmap_bit_p (kills, DECL_UID (sym)))
+ set_livein_block (sym, bb);
+ REWRITE_THIS_STMT (stmt) = 1;
}
+
+ /* Now process the defs. Mark BB as the definition block and add
+ each def to the set of killed symbols. */
+ FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
+ {
+ gcc_assert (DECL_P (def));
+ set_def_block (def, bb, false);
+ bitmap_set_bit (kills, DECL_UID (def));
+ REGISTER_DEFS_IN_THIS_STMT (stmt) = 1;
+ }
+
+ /* If we found the statement interesting then also mark the block BB
+ as interesting. */
+ if (REWRITE_THIS_STMT (stmt) || REGISTER_DEFS_IN_THIS_STMT (stmt))
+ SET_BIT (gd->interesting_blocks, bb->index);
}
-/* Ditto, for ssa name rewriting. */
+/* Structure used by prune_unused_phi_nodes to record bounds of the intervals
+ in the dfs numbering of the dominance tree. */
-static void
-ssa_rewrite_phi_arguments (struct dom_walk_data *walk_data, basic_block bb)
+struct dom_dfsnum
{
- edge e;
- sbitmap names_to_rename = walk_data->global_data;
- use_operand_p op;
-
- for (e = bb->succ; e; e = e->succ_next)
- {
- tree phi;
+ /* Basic block whose index this entry corresponds to. */
+ unsigned bb_index;
- if (e->dest == EXIT_BLOCK_PTR)
- continue;
+ /* The dfs number of this node. */
+ unsigned dfs_num;
+};
- for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
- {
- op = PHI_ARG_DEF_PTR_FROM_EDGE (phi, e);
- if (TREE_CODE (USE_FROM_PTR (op)) != SSA_NAME)
- continue;
+/* Compares two entries of type struct dom_dfsnum by dfs_num field. Callback
+ for qsort. */
- if (!TEST_BIT (names_to_rename, SSA_NAME_VERSION (USE_FROM_PTR (op))))
- continue;
+static int
+cmp_dfsnum (const void *a, const void *b)
+{
+ const struct dom_dfsnum *const da = (const struct dom_dfsnum *) a;
+ const struct dom_dfsnum *const db = (const struct dom_dfsnum *) b;
- SET_USE (op, get_reaching_def (USE_FROM_PTR (op)));
- if (e->flags & EDGE_ABNORMAL)
- SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (op)) = 1;
- }
- }
+ return (int) da->dfs_num - (int) db->dfs_num;
}
-/* SSA Rewriting Step 5. Restore the current reaching definition for each
- variable referenced in the block (in reverse order). */
+/* Among the intervals starting at the N points specified in DEFS, find
+ the one that contains S, and return its bb_index. */
-static void
-rewrite_finalize_block (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED)
+static unsigned
+find_dfsnum_interval (struct dom_dfsnum *defs, unsigned n, unsigned s)
{
- struct rewrite_block_data *bd
- = (struct rewrite_block_data *)VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
+ unsigned f = 0, t = n, m;
- /* Step 5. Restore the current reaching definition for each variable
- referenced in the block (in reverse order). */
- while (bd->block_defs && VARRAY_ACTIVE_SIZE (bd->block_defs) > 0)
+ while (t > f + 1)
{
- tree tmp = VARRAY_TOP_TREE (bd->block_defs);
- tree saved_def, var;
-
- VARRAY_POP (bd->block_defs);
- if (TREE_CODE (tmp) == SSA_NAME)
- {
- saved_def = tmp;
- var = SSA_NAME_VAR (saved_def);
- }
+ m = (f + t) / 2;
+ if (defs[m].dfs_num <= s)
+ f = m;
else
- {
- saved_def = NULL;
- var = tmp;
- }
-
- set_current_def (var, saved_def);
+ t = m;
}
+
+ return defs[f].bb_index;
}
-/* Ditto, for rewriting ssa names. */
+/* Clean bits from PHIS for phi nodes whose value cannot be used in USES.
+ KILLS is a bitmap of blocks where the value is defined before any use. */
static void
-ssa_rewrite_finalize_block (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED)
+prune_unused_phi_nodes (bitmap phis, bitmap kills, bitmap uses)
{
- struct rewrite_block_data *bd
- = (struct rewrite_block_data *)VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
+ VEC(int, heap) *worklist;
+ bitmap_iterator bi;
+ unsigned i, b, p, u, top;
+ bitmap live_phis;
+ basic_block def_bb, use_bb;
+ edge e;
+ edge_iterator ei;
+ bitmap to_remove;
+ struct dom_dfsnum *defs;
+ unsigned n_defs, adef;
- /* Step 5. Restore the current reaching definition for each variable
- referenced in the block (in reverse order). */
- while (bd->block_defs && VARRAY_ACTIVE_SIZE (bd->block_defs) > 0)
+ if (bitmap_empty_p (uses))
{
- tree var;
- tree saved_def = VARRAY_TOP_TREE (bd->block_defs);
- VARRAY_POP (bd->block_defs);
-
- var = VARRAY_TOP_TREE (bd->block_defs);
- VARRAY_POP (bd->block_defs);
+ bitmap_clear (phis);
+ return;
+ }
- set_current_def (var, saved_def);
+ /* The phi must dominate a use, or an argument of a live phi. Also, we
+ do not create any phi nodes in def blocks, unless they are also livein. */
+ to_remove = BITMAP_ALLOC (NULL);
+ bitmap_and_compl (to_remove, kills, uses);
+ bitmap_and_compl_into (phis, to_remove);
+ if (bitmap_empty_p (phis))
+ {
+ BITMAP_FREE (to_remove);
+ return;
}
-}
-/* Dump SSA information to FILE. */
+ /* We want to remove the unnecessary phi nodes, but we do not want to compute
+ liveness information, as that may be linear in the size of CFG, and if
+ there are lot of different variables to rewrite, this may lead to quadratic
+ behavior.
-void
-dump_tree_ssa (FILE *file)
-{
- basic_block bb;
- const char *funcname
- = lang_hooks.decl_printable_name (current_function_decl, 2);
+ Instead, we basically emulate standard dce. We put all uses to worklist,
+ then for each of them find the nearest def that dominates them. If this
+ def is a phi node, we mark it live, and if it was not live before, we
+ add the predecessors of its basic block to the worklist.
+
+ To quickly locate the nearest def that dominates use, we use dfs numbering
+ of the dominance tree (that is already available in order to speed up
+ queries). For each def, we have the interval given by the dfs number on
+ entry to and on exit from the corresponding subtree in the dominance tree.
+ The nearest dominator for a given use is the smallest of these intervals
+ that contains entry and exit dfs numbers for the basic block with the use.
+ If we store the bounds for all the uses to an array and sort it, we can
+ locate the nearest dominating def in logarithmic time by binary search.*/
+ bitmap_ior (to_remove, kills, phis);
+ n_defs = bitmap_count_bits (to_remove);
+ defs = XNEWVEC (struct dom_dfsnum, 2 * n_defs + 1);
+ defs[0].bb_index = 1;
+ defs[0].dfs_num = 0;
+ adef = 1;
+ EXECUTE_IF_SET_IN_BITMAP (to_remove, 0, i, bi)
+ {
+ def_bb = BASIC_BLOCK (i);
+ defs[adef].bb_index = i;
+ defs[adef].dfs_num = bb_dom_dfs_in (CDI_DOMINATORS, def_bb);
+ defs[adef + 1].bb_index = i;
+ defs[adef + 1].dfs_num = bb_dom_dfs_out (CDI_DOMINATORS, def_bb);
+ adef += 2;
+ }
+ BITMAP_FREE (to_remove);
+ gcc_assert (adef == 2 * n_defs + 1);
+ qsort (defs, adef, sizeof (struct dom_dfsnum), cmp_dfsnum);
+ gcc_assert (defs[0].bb_index == 1);
+
+ /* Now each DEFS entry contains the number of the basic block to that the
+ dfs number corresponds. Change them to the number of basic block that
+ corresponds to the interval following the dfs number. Also, for the
+ dfs_out numbers, increase the dfs number by one (so that it corresponds
+ to the start of the following interval, not to the end of the current
+ one). We use WORKLIST as a stack. */
+ worklist = VEC_alloc (int, heap, n_defs + 1);
+ VEC_quick_push (int, worklist, 1);
+ top = 1;
+ n_defs = 1;
+ for (i = 1; i < adef; i++)
+ {
+ b = defs[i].bb_index;
+ if (b == top)
+ {
+ /* This is a closing element. Interval corresponding to the top
+ of the stack after removing it follows. */
+ VEC_pop (int, worklist);
+ top = VEC_index (int, worklist, VEC_length (int, worklist) - 1);
+ defs[n_defs].bb_index = top;
+ defs[n_defs].dfs_num = defs[i].dfs_num + 1;
+ }
+ else
+ {
+ /* Opening element. Nothing to do, just push it to the stack and move
+ it to the correct position. */
+ defs[n_defs].bb_index = defs[i].bb_index;
+ defs[n_defs].dfs_num = defs[i].dfs_num;
+ VEC_quick_push (int, worklist, b);
+ top = b;
+ }
- fprintf (file, "SSA information for %s\n\n", funcname);
+ /* If this interval starts at the same point as the previous one, cancel
+ the previous one. */
+ if (defs[n_defs].dfs_num == defs[n_defs - 1].dfs_num)
+ defs[n_defs - 1].bb_index = defs[n_defs].bb_index;
+ else
+ n_defs++;
+ }
+ VEC_pop (int, worklist);
+ gcc_assert (VEC_empty (int, worklist));
- FOR_EACH_BB (bb)
+ /* Now process the uses. */
+ live_phis = BITMAP_ALLOC (NULL);
+ EXECUTE_IF_SET_IN_BITMAP (uses, 0, i, bi)
{
- dump_bb (bb, file, 0);
- fputs (" ", file);
- print_generic_stmt (file, phi_nodes (bb), dump_flags);
- fputs ("\n\n", file);
+ VEC_safe_push (int, heap, worklist, i);
}
-}
-
-/* Dump SSA information to stderr. */
+ while (!VEC_empty (int, worklist))
+ {
+ b = VEC_pop (int, worklist);
+ if (b == ENTRY_BLOCK)
+ continue;
-void
-debug_tree_ssa (void)
-{
- dump_tree_ssa (stderr);
-}
+ /* If there is a phi node in USE_BB, it is made live. Otherwise,
+ find the def that dominates the immediate dominator of USE_BB
+ (the kill in USE_BB does not dominate the use). */
+ if (bitmap_bit_p (phis, b))
+ p = b;
+ else
+ {
+ use_bb = get_immediate_dominator (CDI_DOMINATORS, BASIC_BLOCK (b));
+ p = find_dfsnum_interval (defs, n_defs,
+ bb_dom_dfs_in (CDI_DOMINATORS, use_bb));
+ if (!bitmap_bit_p (phis, p))
+ continue;
+ }
+ /* If the phi node is already live, there is nothing to do. */
+ if (bitmap_bit_p (live_phis, p))
+ continue;
-/* Dump SSA statistics on FILE. */
+ /* Mark the phi as live, and add the new uses to the worklist. */
+ bitmap_set_bit (live_phis, p);
+ def_bb = BASIC_BLOCK (p);
+ FOR_EACH_EDGE (e, ei, def_bb->preds)
+ {
+ u = e->src->index;
+ if (bitmap_bit_p (uses, u))
+ continue;
-void
-dump_tree_ssa_stats (FILE *file)
-{
- fprintf (file, "\nHash table statistics:\n");
+ /* In case there is a kill directly in the use block, do not record
+ the use (this is also necessary for correctness, as we assume that
+ uses dominated by a def directly in their block have been filtered
+ out before). */
+ if (bitmap_bit_p (kills, u))
+ continue;
- fprintf (file, " def_blocks: ");
- htab_statistics (file, def_blocks);
+ bitmap_set_bit (uses, u);
+ VEC_safe_push (int, heap, worklist, u);
+ }
+ }
- fprintf (file, "\n");
+ VEC_free (int, heap, worklist);
+ bitmap_copy (phis, live_phis);
+ BITMAP_FREE (live_phis);
+ free (defs);
}
+/* Return the set of blocks where variable VAR is defined and the blocks
+ where VAR is live on entry (livein). Return NULL, if no entry is
+ found in DEF_BLOCKS. */
-/* Dump SSA statistics on stderr. */
-
-void
-debug_tree_ssa_stats (void)
+static inline struct def_blocks_d *
+find_def_blocks_for (tree var)
{
- dump_tree_ssa_stats (stderr);
+ struct def_blocks_d dm;
+ dm.var = var;
+ return (struct def_blocks_d *) htab_find (def_blocks, &dm);
}
-/* Dump statistics for the hash table HTAB. */
+/* Retrieve or create a default definition for symbol SYM. */
-static void
-htab_statistics (FILE *file, htab_t htab)
+static inline tree
+get_default_def_for (tree sym)
{
- fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n",
- (long) htab_size (htab),
- (long) htab_elements (htab),
- htab_collisions (htab));
+ tree ddef = gimple_default_def (cfun, sym);
+
+ if (ddef == NULL_TREE)
+ {
+ ddef = make_ssa_name (sym, build_empty_stmt ());
+ set_default_def (sym, ddef);
+ }
+
+ return ddef;
}
-/* Insert PHI nodes for variable VAR using the dominance frontier
- information given in DFS. WORK_STACK is the varray used to
- implement the worklist of basic blocks. */
+/* Marks phi node PHI in basic block BB for rewrite. */
static void
-insert_phi_nodes_for (tree var, bitmap *dfs, varray_type *work_stack)
+mark_phi_for_rewrite (basic_block bb, tree phi)
{
- struct def_blocks_d *def_map;
- bitmap phi_insertion_points;
- int bb_index;
- edge e;
- tree phi;
- basic_block bb;
+ tree_vec phis;
+ unsigned i, idx = bb->index;
- def_map = find_def_blocks_for (var);
- if (def_map == NULL)
+ if (REWRITE_THIS_STMT (phi))
return;
- phi_insertion_points = BITMAP_XMALLOC ();
-
- EXECUTE_IF_SET_IN_BITMAP (def_map->def_blocks, 0, bb_index,
- {
- VARRAY_PUSH_GENERIC_PTR_NOGC (*work_stack, BASIC_BLOCK (bb_index));
- });
-
- /* Pop a block off the worklist, add every block that appears in
- the original block's dfs that we have not already processed to
- the worklist. Iterate until the worklist is empty. Blocks
- which are added to the worklist are potential sites for
- PHI nodes.
-
- The iteration step could be done during PHI insertion just as
- easily. We do it here for historical reasons -- we used to have
- a heuristic which used the potential PHI insertion points to
- determine if fully pruned or semi pruned SSA form was appropriate.
-
- We now always use fully pruned SSA form. */
- while (VARRAY_ACTIVE_SIZE (*work_stack) > 0)
- {
- int dfs_index;
-
- bb = VARRAY_TOP_GENERIC_PTR_NOGC (*work_stack);
- bb_index = bb->index;
-
- VARRAY_POP (*work_stack);
-
- EXECUTE_IF_AND_COMPL_IN_BITMAP (dfs[bb_index],
- phi_insertion_points,
- 0, dfs_index,
- {
- basic_block bb = BASIC_BLOCK (dfs_index);
-
- VARRAY_PUSH_GENERIC_PTR_NOGC (*work_stack, bb);
- bitmap_set_bit (phi_insertion_points, dfs_index);
- });
- }
+ REWRITE_THIS_STMT (phi) = 1;
- /* Remove the blocks where we already have the phis. */
- bitmap_operation (phi_insertion_points, phi_insertion_points,
- def_map->phi_blocks, BITMAP_AND_COMPL);
+ if (!blocks_with_phis_to_rewrite)
+ return;
- /* Now compute global livein for this variable. Note this modifies
- def_map->livein_blocks. */
- compute_global_livein (def_map->livein_blocks, def_map->def_blocks);
+ bitmap_set_bit (blocks_with_phis_to_rewrite, idx);
+ VEC_reserve (tree_vec, heap, phis_to_rewrite, last_basic_block + 1);
+ for (i = VEC_length (tree_vec, phis_to_rewrite); i <= idx; i++)
+ VEC_quick_push (tree_vec, phis_to_rewrite, NULL);
- /* And insert the PHI nodes. */
- EXECUTE_IF_AND_IN_BITMAP (phi_insertion_points, def_map->livein_blocks,
- 0, bb_index,
- do
- {
- bb = BASIC_BLOCK (bb_index);
+ phis = VEC_index (tree_vec, phis_to_rewrite, idx);
+ if (!phis)
+ phis = VEC_alloc (tree, heap, 10);
- phi = create_phi_node (var, bb);
+ VEC_safe_push (tree, heap, phis, phi);
+ VEC_replace (tree_vec, phis_to_rewrite, idx, phis);
+}
- /* If we are rewriting ssa names, add also the phi arguments. */
- if (TREE_CODE (var) == SSA_NAME)
- {
- for (e = bb->pred; e; e = e->pred_next)
- add_phi_arg (&phi, var, e);
- }
- }
- while (0));
- BITMAP_XFREE (phi_insertion_points);
-}
+/* Insert PHI nodes for variable VAR using the iterated dominance
+ frontier given in PHI_INSERTION_POINTS. If UPDATE_P is true, this
+ function assumes that the caller is incrementally updating the
+ existing SSA form, in which case VAR may be an SSA name instead of
+ a symbol.
-/* SSA Rewriting Step 2. Rewrite every variable used in each statement in
- the block with its immediate reaching definitions. Update the current
- definition of a variable when a new real or virtual definition is found. */
+ PHI_INSERTION_POINTS is updated to reflect nodes that already had a
+ PHI node for VAR. On exit, only the nodes that received a PHI node
+ for VAR will be present in PHI_INSERTION_POINTS. */
static void
-rewrite_stmt (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED,
- block_stmt_iterator si)
+insert_phi_nodes_for (tree var, bitmap phi_insertion_points, bool update_p)
{
- stmt_ann_t ann;
- tree stmt;
- use_operand_p use_p;
- def_operand_p def_p;
- ssa_op_iter iter;
- struct rewrite_block_data *bd;
+ unsigned bb_index;
+ edge e;
+ tree phi;
+ basic_block bb;
+ bitmap_iterator bi;
+ struct def_blocks_d *def_map;
- bd = VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
+ def_map = find_def_blocks_for (var);
+ gcc_assert (def_map);
- stmt = bsi_stmt (si);
- ann = stmt_ann (stmt);
+ /* Remove the blocks where we already have PHI nodes for VAR. */
+ bitmap_and_compl_into (phi_insertion_points, def_map->phi_blocks);
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "Renaming statement ");
- print_generic_stmt (dump_file, stmt, TDF_SLIM);
- fprintf (dump_file, "\n");
- }
+ /* Remove obviously useless phi nodes. */
+ prune_unused_phi_nodes (phi_insertion_points, def_map->def_blocks,
+ def_map->livein_blocks);
- /* We have just scanned the code for operands. No statement should
- be modified. */
- gcc_assert (!ann->modified);
+ /* And insert the PHI nodes. */
+ EXECUTE_IF_SET_IN_BITMAP (phi_insertion_points, 0, bb_index, bi)
+ {
+ bb = BASIC_BLOCK (bb_index);
+ if (update_p)
+ mark_block_for_update (bb);
- /* Step 1. Rewrite USES and VUSES in the statement. */
- FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES)
- rewrite_operand (use_p);
+ phi = NULL_TREE;
- /* Step 2. Register the statement's DEF and VDEF operands. */
- FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_ALL_DEFS)
- {
- if (TREE_CODE (DEF_FROM_PTR (def_p)) != SSA_NAME)
- SET_DEF (def_p, make_ssa_name (DEF_FROM_PTR (def_p), stmt));
+ if (TREE_CODE (var) == SSA_NAME)
+ {
+ /* If we are rewriting SSA names, create the LHS of the PHI
+ node by duplicating VAR. This is useful in the case of
+ pointers, to also duplicate pointer attributes (alias
+ information, in particular). */
+ edge_iterator ei;
+ tree new_lhs;
+
+ gcc_assert (update_p);
+ phi = create_phi_node (var, bb);
+
+ new_lhs = duplicate_ssa_name (var, phi);
+ SET_PHI_RESULT (phi, new_lhs);
+ add_new_name_mapping (new_lhs, var);
+
+ /* Add VAR to every argument slot of PHI. We need VAR in
+ every argument so that rewrite_update_phi_arguments knows
+ which name is this PHI node replacing. If VAR is a
+ symbol marked for renaming, this is not necessary, the
+ renamer will use the symbol on the LHS to get its
+ reaching definition. */
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ add_phi_arg (phi, var, e);
+ }
+ else
+ {
+ tree sym = DECL_P (var) ? var : SSA_NAME_VAR (var);
+ phi = create_phi_node (sym, bb);
+ }
- /* FIXME: We shouldn't be registering new defs if the variable
- doesn't need to be renamed. */
- register_new_def (DEF_FROM_PTR (def_p), &bd->block_defs);
+ /* Mark this PHI node as interesting for update_ssa. */
+ REGISTER_DEFS_IN_THIS_STMT (phi) = 1;
+ mark_phi_for_rewrite (bb, phi);
}
}
-/* Ditto, for rewriting ssa names. */
+
+/* Insert PHI nodes at the dominance frontier of blocks with variable
+ definitions. DFS contains the dominance frontier information for
+ the flowgraph. */
static void
-ssa_rewrite_stmt (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED,
- block_stmt_iterator si)
+insert_phi_nodes (bitmap *dfs)
{
- stmt_ann_t ann;
- tree stmt, var;
- ssa_op_iter iter;
- use_operand_p use_p;
- def_operand_p def_p;
- struct rewrite_block_data *bd;
- sbitmap names_to_rename = walk_data->global_data;
-
- bd = VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
-
- stmt = bsi_stmt (si);
- ann = stmt_ann (stmt);
-
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "Renaming statement ");
- print_generic_stmt (dump_file, stmt, TDF_SLIM);
- fprintf (dump_file, "\n");
- }
-
- /* We have just scanned the code for operands. No statement should
- be modified. */
- gcc_assert (!ann->modified);
-
- /* Step 1. Rewrite USES and VUSES in the statement. */
- FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES)
- {
- if (TEST_BIT (names_to_rename, SSA_NAME_VERSION (USE_FROM_PTR (use_p))))
- SET_USE (use_p, get_reaching_def (USE_FROM_PTR (use_p)));
- }
+ referenced_var_iterator rvi;
+ tree var;
- /* Step 2. Register the statement's DEF and VDEF operands. */
- FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_ALL_DEFS)
+ timevar_push (TV_TREE_INSERT_PHI_NODES);
+
+ FOR_EACH_REFERENCED_VAR (var, rvi)
{
- var = DEF_FROM_PTR (def_p);
+ struct def_blocks_d *def_map;
+ bitmap idf;
- if (!TEST_BIT (names_to_rename, SSA_NAME_VERSION (var)))
+ def_map = find_def_blocks_for (var);
+ if (def_map == NULL)
continue;
- SET_DEF (def_p, duplicate_ssa_name (var, stmt));
- ssa_register_new_def (var, DEF_FROM_PTR (def_p), &bd->block_defs);
+ if (get_phi_state (var) != NEED_PHI_STATE_NO)
+ {
+ idf = compute_idf (def_map->def_blocks, dfs);
+ insert_phi_nodes_for (var, idf, false);
+ BITMAP_FREE (idf);
+ }
}
-}
-/* Replace the operand pointed by OP_P with its immediate reaching
- definition. */
-
-static inline void
-rewrite_operand (use_operand_p op_p)
-{
- if (TREE_CODE (USE_FROM_PTR (op_p)) != SSA_NAME)
- SET_USE (op_p, get_reaching_def (USE_FROM_PTR (op_p)));
+ timevar_pop (TV_TREE_INSERT_PHI_NODES);
}
-/* Register DEF (an SSA_NAME) to be a new definition for its underlying
- variable (SSA_NAME_VAR (DEF)) and push VAR's current reaching definition
- into the stack pointed by BLOCK_DEFS_P. */
-void
-register_new_def (tree def, varray_type *block_defs_p)
+/* Push SYM's current reaching definition into BLOCK_DEFS_STACK and
+ register DEF (an SSA_NAME) to be a new definition for SYM. */
+
+static void
+register_new_def (tree def, tree sym)
{
- tree var = SSA_NAME_VAR (def);
tree currdef;
/* If this variable is set in a single basic block and all uses are
This is the same test to prune the set of variables which may
need PHI nodes. So we just use that information since it's already
computed and available for us to use. */
- if (get_phi_state (var) == NEED_PHI_STATE_NO)
+ if (get_phi_state (sym) == NEED_PHI_STATE_NO)
{
- set_current_def (var, def);
+ set_current_def (sym, def);
return;
}
- currdef = get_current_def (var);
- if (! *block_defs_p)
- VARRAY_TREE_INIT (*block_defs_p, 20, "block_defs");
-
- /* Push the current reaching definition into *BLOCK_DEFS_P. This stack is
- later used by the dominator tree callbacks to restore the reaching
- definitions for all the variables defined in the block after a recursive
- visit to all its immediately dominated blocks. If there is no current
- reaching definition, then just record the underlying _DECL node. */
- VARRAY_PUSH_TREE (*block_defs_p, currdef ? currdef : var);
-
- /* Set the current reaching definition for VAR to be DEF. */
- set_current_def (var, def);
+ currdef = get_current_def (sym);
+
+ /* If SYM is not a GIMPLE register, then CURRDEF may be a name whose
+ SSA_NAME_VAR is not necessarily SYM. In this case, also push SYM
+ in the stack so that we know which symbol is being defined by
+ this SSA name when we unwind the stack. */
+ if (currdef && !is_gimple_reg (sym))
+ VEC_safe_push (tree, heap, block_defs_stack, sym);
+
+ /* Push the current reaching definition into BLOCK_DEFS_STACK. This
+ stack is later used by the dominator tree callbacks to restore
+ the reaching definitions for all the variables defined in the
+ block after a recursive visit to all its immediately dominated
+ blocks. If there is no current reaching definition, then just
+ record the underlying _DECL node. */
+ VEC_safe_push (tree, heap, block_defs_stack, currdef ? currdef : sym);
+
+ /* Set the current reaching definition for SYM to be DEF. */
+ set_current_def (sym, def);
}
-/* Return the current definition for variable VAR. If none is found,
- create a new SSA name to act as the zeroth definition for VAR. If VAR
- is call clobbered and there exists a more recent definition of
- GLOBAL_VAR, return the definition for GLOBAL_VAR. This means that VAR
- has been clobbered by a function call since its last assignment. */
-
-static tree
-get_reaching_def (tree var)
-{
- tree default_d, currdef_var, avar;
-
- /* Lookup the current reaching definition for VAR. */
- default_d = NULL_TREE;
- currdef_var = get_current_def (var);
- /* If there is no reaching definition for VAR, create and register a
- default definition for it (if needed). */
- if (currdef_var == NULL_TREE)
- {
- if (TREE_CODE (var) == SSA_NAME)
- avar = SSA_NAME_VAR (var);
- else
- avar = var;
+/* Perform a depth-first traversal of the dominator tree looking for
+ variables to rename. BB is the block where to start searching.
+ Renaming is a five step process:
- default_d = default_def (avar);
- if (default_d == NULL_TREE)
- {
- default_d = make_ssa_name (avar, build_empty_stmt ());
- set_default_def (avar, default_d);
- }
- set_current_def (var, default_d);
- }
+ 1- Every definition made by PHI nodes at the start of the blocks is
+ registered as the current definition for the corresponding variable.
- /* Return the current reaching definition for VAR, or the default
- definition, if we had to create one. */
- return (currdef_var) ? currdef_var : default_d;
-}
+ 2- Every statement in BB is rewritten. USE and VUSE operands are
+ rewritten with their corresponding reaching definition. DEF and
+ VDEF targets are registered as new definitions.
+
+ 3- All the PHI nodes in successor blocks of BB are visited. The
+ argument corresponding to BB is replaced with its current reaching
+ definition.
+ 4- Recursively rewrite every dominator child block of BB.
-/* Hashing and equality functions for DEF_BLOCKS. */
+ 5- Restore (in reverse order) the current reaching definition for every
+ new definition introduced in this block. This is done so that when
+ we return from the recursive call, all the current reaching
+ definitions are restored to the names that were valid in the
+ dominator parent of BB. */
+
+/* SSA Rewriting Step 1. Initialization, create a block local stack
+ of reaching definitions for new SSA names produced in this block
+ (BLOCK_DEFS). Register new definitions for every PHI node in the
+ block. */
+
+static void
+rewrite_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
+{
+ tree phi;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "\n\nRenaming block #%d\n\n", bb->index);
+
+ /* Mark the unwind point for this block. */
+ VEC_safe_push (tree, heap, block_defs_stack, NULL_TREE);
+
+ /* Step 1. Register new definitions for every PHI node in the block.
+ Conceptually, all the PHI nodes are executed in parallel and each PHI
+ node introduces a new version for the associated variable. */
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ {
+ tree result = PHI_RESULT (phi);
+ gcc_assert (is_gimple_reg (result));
+ register_new_def (result, SSA_NAME_VAR (result));
+ }
+}
+
+
+/* Return the current definition for variable VAR. If none is found,
+ create a new SSA name to act as the zeroth definition for VAR. */
+
+static tree
+get_reaching_def (tree var)
+{
+ tree currdef;
+
+ /* Lookup the current reaching definition for VAR. */
+ currdef = get_current_def (var);
+
+ /* If there is no reaching definition for VAR, create and register a
+ default definition for it (if needed). */
+ if (currdef == NULL_TREE)
+ {
+ tree sym = DECL_P (var) ? var : SSA_NAME_VAR (var);
+ currdef = get_default_def_for (sym);
+ set_current_def (var, currdef);
+ }
+
+ /* Return the current reaching definition for VAR, or the default
+ definition, if we had to create one. */
+ return currdef;
+}
+
+
+/* SSA Rewriting Step 2. Rewrite every variable used in each statement in
+ the block with its immediate reaching definitions. Update the current
+ definition of a variable when a new real or virtual definition is found. */
+
+static void
+rewrite_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb ATTRIBUTE_UNUSED, block_stmt_iterator si)
+{
+ tree stmt;
+ use_operand_p use_p;
+ def_operand_p def_p;
+ ssa_op_iter iter;
+
+ stmt = bsi_stmt (si);
+
+ /* If mark_def_sites decided that we don't need to rewrite this
+ statement, ignore it. */
+ gcc_assert (blocks_to_update == NULL);
+ if (!REWRITE_THIS_STMT (stmt) && !REGISTER_DEFS_IN_THIS_STMT (stmt))
+ return;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Renaming statement ");
+ print_generic_stmt (dump_file, stmt, TDF_SLIM);
+ fprintf (dump_file, "\n");
+ }
+
+ /* Step 1. Rewrite USES in the statement. */
+ if (REWRITE_THIS_STMT (stmt))
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
+ {
+ tree var = USE_FROM_PTR (use_p);
+ gcc_assert (DECL_P (var));
+ SET_USE (use_p, get_reaching_def (var));
+ }
+
+ /* Step 2. Register the statement's DEF operands. */
+ if (REGISTER_DEFS_IN_THIS_STMT (stmt))
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_DEF)
+ {
+ tree var = DEF_FROM_PTR (def_p);
+ gcc_assert (DECL_P (var));
+ SET_DEF (def_p, make_ssa_name (var, stmt));
+ register_new_def (DEF_FROM_PTR (def_p), var);
+ }
+}
+
+
+/* SSA Rewriting Step 3. Visit all the successor blocks of BB looking for
+ PHI nodes. For every PHI node found, add a new argument containing the
+ current reaching definition for the variable and the edge through which
+ that definition is reaching the PHI node. */
+
+static void
+rewrite_add_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ tree phi;
+
+ for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
+ {
+ tree currdef;
+ currdef = get_reaching_def (SSA_NAME_VAR (PHI_RESULT (phi)));
+ add_phi_arg (phi, currdef, e);
+ }
+ }
+}
+
+
+/* Called after visiting all the statements in basic block BB and all
+ of its dominator children. Restore CURRDEFS to its original value. */
+
+static void
+rewrite_finalize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb ATTRIBUTE_UNUSED)
+{
+ /* Restore CURRDEFS to its original state. */
+ while (VEC_length (tree, block_defs_stack) > 0)
+ {
+ tree tmp = VEC_pop (tree, block_defs_stack);
+ tree saved_def, var;
+
+ if (tmp == NULL_TREE)
+ break;
+
+ if (TREE_CODE (tmp) == SSA_NAME)
+ {
+ /* If we recorded an SSA_NAME, then make the SSA_NAME the
+ current definition of its underlying variable. Note that
+ if the SSA_NAME is not for a GIMPLE register, the symbol
+ being defined is stored in the next slot in the stack.
+ This mechanism is needed because an SSA name for a
+ non-register symbol may be the definition for more than
+ one symbol (e.g., SFTs, aliased variables, etc). */
+ saved_def = tmp;
+ var = SSA_NAME_VAR (saved_def);
+ if (!is_gimple_reg (var))
+ var = VEC_pop (tree, block_defs_stack);
+ }
+ else
+ {
+ /* If we recorded anything else, it must have been a _DECL
+ node and its current reaching definition must have been
+ NULL. */
+ saved_def = NULL;
+ var = tmp;
+ }
+
+ set_current_def (var, saved_def);
+ }
+}
+
+
+/* Dump bitmap SET (assumed to contain VAR_DECLs) to FILE. */
+
+void
+dump_decl_set (FILE *file, bitmap set)
+{
+ if (set)
+ {
+ bitmap_iterator bi;
+ unsigned i;
+
+ fprintf (file, "{ ");
+
+ EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi)
+ {
+ print_generic_expr (file, referenced_var (i), 0);
+ fprintf (file, " ");
+ }
+
+ fprintf (file, "}\n");
+ }
+ else
+ fprintf (file, "NIL\n");
+}
+
+
+/* Dump bitmap SET (assumed to contain VAR_DECLs) to FILE. */
+
+void
+debug_decl_set (bitmap set)
+{
+ dump_decl_set (stderr, set);
+}
+
+
+/* Dump the renaming stack (block_defs_stack) to FILE. Traverse the
+ stack up to a maximum of N levels. If N is -1, the whole stack is
+ dumped. New levels are created when the dominator tree traversal
+ used for renaming enters a new sub-tree. */
+
+void
+dump_defs_stack (FILE *file, int n)
+{
+ int i, j;
+
+ fprintf (file, "\n\nRenaming stack");
+ if (n > 0)
+ fprintf (file, " (up to %d levels)", n);
+ fprintf (file, "\n\n");
+
+ i = 1;
+ fprintf (file, "Level %d (current level)\n", i);
+ for (j = (int) VEC_length (tree, block_defs_stack) - 1; j >= 0; j--)
+ {
+ tree name, var;
+
+ name = VEC_index (tree, block_defs_stack, j);
+ if (name == NULL_TREE)
+ {
+ i++;
+ if (n > 0 && i > n)
+ break;
+ fprintf (file, "\nLevel %d\n", i);
+ continue;
+ }
+
+ if (DECL_P (name))
+ {
+ var = name;
+ name = NULL_TREE;
+ }
+ else
+ {
+ var = SSA_NAME_VAR (name);
+ if (!is_gimple_reg (var))
+ {
+ j--;
+ var = VEC_index (tree, block_defs_stack, j);
+ }
+ }
+
+ fprintf (file, " Previous CURRDEF (");
+ print_generic_expr (file, var, 0);
+ fprintf (file, ") = ");
+ if (name)
+ print_generic_expr (file, name, 0);
+ else
+ fprintf (file, "<NIL>");
+ fprintf (file, "\n");
+ }
+}
+
+
+/* Dump the renaming stack (block_defs_stack) to stderr. Traverse the
+ stack up to a maximum of N levels. If N is -1, the whole stack is
+ dumped. New levels are created when the dominator tree traversal
+ used for renaming enters a new sub-tree. */
+
+void
+debug_defs_stack (int n)
+{
+ dump_defs_stack (stderr, n);
+}
+
+
+/* Dump the current reaching definition of every symbol to FILE. */
+
+void
+dump_currdefs (FILE *file)
+{
+ referenced_var_iterator i;
+ tree var;
+
+ fprintf (file, "\n\nCurrent reaching definitions\n\n");
+ FOR_EACH_REFERENCED_VAR (var, i)
+ if (syms_to_rename == NULL || bitmap_bit_p (syms_to_rename, DECL_UID (var)))
+ {
+ fprintf (file, "CURRDEF (");
+ print_generic_expr (file, var, 0);
+ fprintf (file, ") = ");
+ if (get_current_def (var))
+ print_generic_expr (file, get_current_def (var), 0);
+ else
+ fprintf (file, "<NIL>");
+ fprintf (file, "\n");
+ }
+}
+
+
+/* Dump the current reaching definition of every symbol to stderr. */
+
+void
+debug_currdefs (void)
+{
+ dump_currdefs (stderr);
+}
+
+
+/* Dump SSA information to FILE. */
+
+void
+dump_tree_ssa (FILE *file)
+{
+ const char *funcname
+ = lang_hooks.decl_printable_name (current_function_decl, 2);
+
+ fprintf (file, "SSA renaming information for %s\n\n", funcname);
+
+ dump_def_blocks (file);
+ dump_defs_stack (file, -1);
+ dump_currdefs (file);
+ dump_tree_ssa_stats (file);
+}
+
+
+/* Dump SSA information to stderr. */
+
+void
+debug_tree_ssa (void)
+{
+ dump_tree_ssa (stderr);
+}
+
+
+/* Dump statistics for the hash table HTAB. */
+
+static void
+htab_statistics (FILE *file, htab_t htab)
+{
+ fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n",
+ (long) htab_size (htab),
+ (long) htab_elements (htab),
+ htab_collisions (htab));
+}
+
+
+/* Dump SSA statistics on FILE. */
+
+void
+dump_tree_ssa_stats (FILE *file)
+{
+ if (def_blocks || repl_tbl)
+ fprintf (file, "\nHash table statistics:\n");
+
+ if (def_blocks)
+ {
+ fprintf (file, " def_blocks: ");
+ htab_statistics (file, def_blocks);
+ }
+
+ if (repl_tbl)
+ {
+ fprintf (file, " repl_tbl: ");
+ htab_statistics (file, repl_tbl);
+ }
+
+ if (def_blocks || repl_tbl)
+ fprintf (file, "\n");
+}
+
+
+/* Dump SSA statistics on stderr. */
+
+void
+debug_tree_ssa_stats (void)
+{
+ dump_tree_ssa_stats (stderr);
+}
+
+
+/* Hashing and equality functions for DEF_BLOCKS. */
static hashval_t
def_blocks_hash (const void *p)
== ((const struct def_blocks_d *)p2)->var;
}
+
/* Free memory allocated by one entry in DEF_BLOCKS. */
static void
def_blocks_free (void *p)
{
- struct def_blocks_d *entry = p;
- BITMAP_XFREE (entry->def_blocks);
- BITMAP_XFREE (entry->phi_blocks);
- BITMAP_XFREE (entry->livein_blocks);
+ struct def_blocks_d *entry = (struct def_blocks_d *) p;
+ BITMAP_FREE (entry->def_blocks);
+ BITMAP_FREE (entry->phi_blocks);
+ BITMAP_FREE (entry->livein_blocks);
free (entry);
}
-/* Dump the DEF_BLOCKS hash table on stderr. */
+/* Callback for htab_traverse to dump the DEF_BLOCKS hash table. */
+
+static int
+debug_def_blocks_r (void **slot, void *data)
+{
+ FILE *file = (FILE *) data;
+ struct def_blocks_d *db_p = (struct def_blocks_d *) *slot;
+
+ fprintf (file, "VAR: ");
+ print_generic_expr (file, db_p->var, dump_flags);
+ bitmap_print (file, db_p->def_blocks, ", DEF_BLOCKS: { ", "}");
+ bitmap_print (file, db_p->livein_blocks, ", LIVEIN_BLOCKS: { ", "}");
+ bitmap_print (file, db_p->phi_blocks, ", PHI_BLOCKS: { ", "}\n");
+
+ return 1;
+}
+
+
+/* Dump the DEF_BLOCKS hash table on FILE. */
+
+void
+dump_def_blocks (FILE *file)
+{
+ fprintf (file, "\n\nDefinition and live-in blocks:\n\n");
+ if (def_blocks)
+ htab_traverse (def_blocks, debug_def_blocks_r, file);
+}
+
+
+/* Dump the DEF_BLOCKS hash table on stderr. */
+
+void
+debug_def_blocks (void)
+{
+ dump_def_blocks (stderr);
+}
+
+
+/* Register NEW_NAME to be the new reaching definition for OLD_NAME. */
+
+static inline void
+register_new_update_single (tree new_name, tree old_name)
+{
+ tree currdef = get_current_def (old_name);
+
+ /* Push the current reaching definition into BLOCK_DEFS_STACK.
+ This stack is later used by the dominator tree callbacks to
+ restore the reaching definitions for all the variables
+ defined in the block after a recursive visit to all its
+ immediately dominated blocks. */
+ VEC_reserve (tree, heap, block_defs_stack, 2);
+ VEC_quick_push (tree, block_defs_stack, currdef);
+ VEC_quick_push (tree, block_defs_stack, old_name);
+
+ /* Set the current reaching definition for OLD_NAME to be
+ NEW_NAME. */
+ set_current_def (old_name, new_name);
+}
+
+
+/* Register NEW_NAME to be the new reaching definition for all the
+ names in OLD_NAMES. Used by the incremental SSA update routines to
+ replace old SSA names with new ones. */
+
+static inline void
+register_new_update_set (tree new_name, bitmap old_names)
+{
+ bitmap_iterator bi;
+ unsigned i;
+
+ EXECUTE_IF_SET_IN_BITMAP (old_names, 0, i, bi)
+ register_new_update_single (new_name, ssa_name (i));
+}
+
+
+/* Initialization of block data structures for the incremental SSA
+ update pass. Create a block local stack of reaching definitions
+ for new SSA names produced in this block (BLOCK_DEFS). Register
+ new definitions for every PHI node in the block. */
+
+static void
+rewrite_update_init_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+ tree phi;
+ bool is_abnormal_phi;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "\n\nRegistering new PHI nodes in block #%d\n\n",
+ bb->index);
+
+ /* Mark the unwind point for this block. */
+ VEC_safe_push (tree, heap, block_defs_stack, NULL_TREE);
+
+ if (!bitmap_bit_p (blocks_to_update, bb->index))
+ return;
+
+ /* Mark the LHS if any of the arguments flows through an abnormal
+ edge. */
+ is_abnormal_phi = false;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (e->flags & EDGE_ABNORMAL)
+ {
+ is_abnormal_phi = true;
+ break;
+ }
+
+ /* If any of the PHI nodes is a replacement for a name in
+ OLD_SSA_NAMES or it's one of the names in NEW_SSA_NAMES, then
+ register it as a new definition for its corresponding name. Also
+ register definitions for names whose underlying symbols are
+ marked for renaming. */
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ {
+ tree lhs, lhs_sym;
+
+ if (!REGISTER_DEFS_IN_THIS_STMT (phi))
+ continue;
+
+ lhs = PHI_RESULT (phi);
+ lhs_sym = SSA_NAME_VAR (lhs);
+
+ if (symbol_marked_for_renaming (lhs_sym))
+ register_new_update_single (lhs, lhs_sym);
+ else
+ {
+
+ /* If LHS is a new name, register a new definition for all
+ the names replaced by LHS. */
+ if (is_new_name (lhs))
+ register_new_update_set (lhs, names_replaced_by (lhs));
+
+ /* If LHS is an OLD name, register it as a new definition
+ for itself. */
+ if (is_old_name (lhs))
+ register_new_update_single (lhs, lhs);
+ }
+
+ if (is_abnormal_phi)
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs) = 1;
+ }
+}
+
+
+/* Called after visiting block BB. Unwind BLOCK_DEFS_STACK to restore
+ the current reaching definition of every name re-written in BB to
+ the original reaching definition before visiting BB. This
+ unwinding must be done in the opposite order to what is done in
+ register_new_update_set. */
+
+static void
+rewrite_update_fini_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb ATTRIBUTE_UNUSED)
+{
+ while (VEC_length (tree, block_defs_stack) > 0)
+ {
+ tree var = VEC_pop (tree, block_defs_stack);
+ tree saved_def;
+
+ /* NULL indicates the unwind stop point for this block (see
+ rewrite_update_init_block). */
+ if (var == NULL)
+ return;
+
+ saved_def = VEC_pop (tree, block_defs_stack);
+ set_current_def (var, saved_def);
+ }
+}
+
+
+/* If the operand pointed to by USE_P is a name in OLD_SSA_NAMES or
+ it is a symbol marked for renaming, replace it with USE_P's current
+ reaching definition. */
+
+static inline void
+maybe_replace_use (use_operand_p use_p)
+{
+ tree rdef = NULL_TREE;
+ tree use = USE_FROM_PTR (use_p);
+ tree sym = DECL_P (use) ? use : SSA_NAME_VAR (use);
+
+ if (symbol_marked_for_renaming (sym))
+ rdef = get_reaching_def (sym);
+ else if (is_old_name (use))
+ rdef = get_reaching_def (use);
+
+ if (rdef && rdef != use)
+ SET_USE (use_p, rdef);
+}
+
+
+/* If the operand pointed to by DEF_P is an SSA name in NEW_SSA_NAMES
+ or OLD_SSA_NAMES, or if it is a symbol marked for renaming,
+ register it as the current definition for the names replaced by
+ DEF_P. */
+
+static inline void
+maybe_register_def (def_operand_p def_p, tree stmt)
+{
+ tree def = DEF_FROM_PTR (def_p);
+ tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def);
+
+ /* If DEF is a naked symbol that needs renaming, create a new
+ name for it. */
+ if (symbol_marked_for_renaming (sym))
+ {
+ if (DECL_P (def))
+ {
+ def = make_ssa_name (def, stmt);
+ SET_DEF (def_p, def);
+ }
+
+ register_new_update_single (def, sym);
+ }
+ else
+ {
+ /* If DEF is a new name, register it as a new definition
+ for all the names replaced by DEF. */
+ if (is_new_name (def))
+ register_new_update_set (def, names_replaced_by (def));
+
+ /* If DEF is an old name, register DEF as a new
+ definition for itself. */
+ if (is_old_name (def))
+ register_new_update_single (def, def);
+ }
+}
+
+
+/* Update every variable used in the statement pointed-to by SI. The
+ statement is assumed to be in SSA form already. Names in
+ OLD_SSA_NAMES used by SI will be updated to their current reaching
+ definition. Names in OLD_SSA_NAMES or NEW_SSA_NAMES defined by SI
+ will be registered as a new definition for their corresponding name
+ in OLD_SSA_NAMES. */
+
+static void
+rewrite_update_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb ATTRIBUTE_UNUSED,
+ block_stmt_iterator si)
+{
+ stmt_ann_t ann;
+ tree stmt;
+ use_operand_p use_p;
+ def_operand_p def_p;
+ ssa_op_iter iter;
+
+ stmt = bsi_stmt (si);
+ ann = stmt_ann (stmt);
+
+ gcc_assert (bitmap_bit_p (blocks_to_update, bb->index));
+
+ /* Only update marked statements. */
+ if (!REWRITE_THIS_STMT (stmt) && !REGISTER_DEFS_IN_THIS_STMT (stmt))
+ return;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Updating SSA information for statement ");
+ print_generic_stmt (dump_file, stmt, TDF_SLIM);
+ fprintf (dump_file, "\n");
+ }
+
+ /* Rewrite USES included in OLD_SSA_NAMES and USES whose underlying
+ symbol is marked for renaming. */
+ if (REWRITE_THIS_STMT (stmt))
+ {
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
+ maybe_replace_use (use_p);
+
+ if (need_to_update_vops_p)
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_VIRTUAL_USES)
+ maybe_replace_use (use_p);
+ }
+
+ /* Register definitions of names in NEW_SSA_NAMES and OLD_SSA_NAMES.
+ Also register definitions for names whose underlying symbol is
+ marked for renaming. */
+ if (REGISTER_DEFS_IN_THIS_STMT (stmt))
+ {
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_DEF)
+ maybe_register_def (def_p, stmt);
+
+ if (need_to_update_vops_p)
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_VIRTUAL_DEFS)
+ maybe_register_def (def_p, stmt);
+ }
+}
+
+
+/* Visit all the successor blocks of BB looking for PHI nodes. For
+ every PHI node found, check if any of its arguments is in
+ OLD_SSA_NAMES. If so, and if the argument has a current reaching
+ definition, replace it. */
+
+static void
+rewrite_update_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+ unsigned i;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ tree phi;
+ tree_vec phis;
+
+ if (!bitmap_bit_p (blocks_with_phis_to_rewrite, e->dest->index))
+ continue;
+
+ phis = VEC_index (tree_vec, phis_to_rewrite, e->dest->index);
+ for (i = 0; VEC_iterate (tree, phis, i, phi); i++)
+ {
+ tree arg, lhs_sym;
+ use_operand_p arg_p;
+
+ gcc_assert (REWRITE_THIS_STMT (phi));
+
+ arg_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, e);
+ arg = USE_FROM_PTR (arg_p);
+
+ if (arg && !DECL_P (arg) && TREE_CODE (arg) != SSA_NAME)
+ continue;
+
+ lhs_sym = SSA_NAME_VAR (PHI_RESULT (phi));
+
+ if (arg == NULL_TREE)
+ {
+ /* When updating a PHI node for a recently introduced
+ symbol we may find NULL arguments. That's why we
+ take the symbol from the LHS of the PHI node. */
+ SET_USE (arg_p, get_reaching_def (lhs_sym));
+ }
+ else
+ {
+ tree sym = DECL_P (arg) ? arg : SSA_NAME_VAR (arg);
+
+ if (symbol_marked_for_renaming (sym))
+ SET_USE (arg_p, get_reaching_def (sym));
+ else if (is_old_name (arg))
+ SET_USE (arg_p, get_reaching_def (arg));
+ }
+
+ if (e->flags & EDGE_ABNORMAL)
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (arg_p)) = 1;
+ }
+ }
+}
+
+
+/* Rewrite the actual blocks, statements, and PHI arguments, to be in SSA
+ form.
+
+ ENTRY indicates the block where to start. Every block dominated by
+ ENTRY will be rewritten.
+
+ WHAT indicates what actions will be taken by the renamer (see enum
+ rewrite_mode).
+
+ BLOCKS are the set of interesting blocks for the dominator walker
+ to process. If this set is NULL, then all the nodes dominated
+ by ENTRY are walked. Otherwise, blocks dominated by ENTRY that
+ are not present in BLOCKS are ignored. */
+
+static void
+rewrite_blocks (basic_block entry, enum rewrite_mode what, sbitmap blocks)
+{
+ struct dom_walk_data walk_data;
+
+ /* Rewrite all the basic blocks in the program. */
+ timevar_push (TV_TREE_SSA_REWRITE_BLOCKS);
+
+ /* Setup callbacks for the generic dominator tree walker. */
+ memset (&walk_data, 0, sizeof (walk_data));
+
+ walk_data.dom_direction = CDI_DOMINATORS;
+ walk_data.interesting_blocks = blocks;
+
+ if (what == REWRITE_ALL)
+ walk_data.before_dom_children_before_stmts = rewrite_initialize_block;
+ else
+ walk_data.before_dom_children_before_stmts = rewrite_update_init_block;
+
+ if (what == REWRITE_ALL)
+ walk_data.before_dom_children_walk_stmts = rewrite_stmt;
+ else if (what == REWRITE_UPDATE)
+ walk_data.before_dom_children_walk_stmts = rewrite_update_stmt;
+ else
+ gcc_unreachable ();
+
+ if (what == REWRITE_ALL)
+ walk_data.before_dom_children_after_stmts = rewrite_add_phi_arguments;
+ else if (what == REWRITE_UPDATE)
+ walk_data.before_dom_children_after_stmts = rewrite_update_phi_arguments;
+ else
+ gcc_unreachable ();
+
+ if (what == REWRITE_ALL)
+ walk_data.after_dom_children_after_stmts = rewrite_finalize_block;
+ else if (what == REWRITE_UPDATE)
+ walk_data.after_dom_children_after_stmts = rewrite_update_fini_block;
+ else
+ gcc_unreachable ();
+
+ block_defs_stack = VEC_alloc (tree, heap, 10);
+
+ /* Initialize the dominator walker. */
+ init_walk_dominator_tree (&walk_data);
+
+ /* Recursively walk the dominator tree rewriting each statement in
+ each basic block. */
+ walk_dominator_tree (&walk_data, entry);
+
+ /* Finalize the dominator walker. */
+ fini_walk_dominator_tree (&walk_data);
+
+ /* Debugging dumps. */
+ if (dump_file && (dump_flags & TDF_STATS))
+ {
+ dump_dfa_stats (dump_file);
+ if (def_blocks)
+ dump_tree_ssa_stats (dump_file);
+ }
+
+ VEC_free (tree, heap, block_defs_stack);
+
+ timevar_pop (TV_TREE_SSA_REWRITE_BLOCKS);
+}
+
+
+/* Block initialization routine for mark_def_sites. Clear the
+ KILLS bitmap at the start of each block. */
+
+static void
+mark_def_sites_initialize_block (struct dom_walk_data *walk_data,
+ basic_block bb ATTRIBUTE_UNUSED)
+{
+ struct mark_def_sites_global_data *gd;
+ gd = (struct mark_def_sites_global_data *) walk_data->global_data;
+ bitmap_clear (gd->kills);
+}
+
+
+/* Mark the definition site blocks for each variable, so that we know
+ where the variable is actually live.
+
+ INTERESTING_BLOCKS will be filled in with all the blocks that
+ should be processed by the renamer. It is assumed to be
+ initialized and zeroed by the caller. */
+
+static void
+mark_def_site_blocks (sbitmap interesting_blocks)
+{
+ struct dom_walk_data walk_data;
+ struct mark_def_sites_global_data mark_def_sites_global_data;
+
+ /* Setup callbacks for the generic dominator tree walker to find and
+ mark definition sites. */
+ walk_data.walk_stmts_backward = false;
+ walk_data.dom_direction = CDI_DOMINATORS;
+ walk_data.initialize_block_local_data = NULL;
+ walk_data.before_dom_children_before_stmts = mark_def_sites_initialize_block;
+ walk_data.before_dom_children_walk_stmts = mark_def_sites;
+ walk_data.before_dom_children_after_stmts = NULL;
+ walk_data.after_dom_children_before_stmts = NULL;
+ walk_data.after_dom_children_walk_stmts = NULL;
+ walk_data.after_dom_children_after_stmts = NULL;
+ walk_data.interesting_blocks = NULL;
+
+ /* Notice that this bitmap is indexed using variable UIDs, so it must be
+ large enough to accommodate all the variables referenced in the
+ function, not just the ones we are renaming. */
+ mark_def_sites_global_data.kills = BITMAP_ALLOC (NULL);
+
+ /* Create the set of interesting blocks that will be filled by
+ mark_def_sites. */
+ mark_def_sites_global_data.interesting_blocks = interesting_blocks;
+ walk_data.global_data = &mark_def_sites_global_data;
+
+ /* We do not have any local data. */
+ walk_data.block_local_data_size = 0;
+
+ /* Initialize the dominator walker. */
+ init_walk_dominator_tree (&walk_data);
+
+ /* Recursively walk the dominator tree. */
+ walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
+
+ /* Finalize the dominator walker. */
+ fini_walk_dominator_tree (&walk_data);
+
+ /* We no longer need this bitmap, clear and free it. */
+ BITMAP_FREE (mark_def_sites_global_data.kills);
+}
+
+
+/* Initialize internal data needed during renaming. */
+
+static void
+init_ssa_renamer (void)
+{
+ tree var;
+ referenced_var_iterator rvi;
+
+ cfun->gimple_df->in_ssa_p = false;
+
+ /* Allocate memory for the DEF_BLOCKS hash table. */
+ gcc_assert (def_blocks == NULL);
+ def_blocks = htab_create (num_referenced_vars, def_blocks_hash,
+ def_blocks_eq, def_blocks_free);
+
+ FOR_EACH_REFERENCED_VAR(var, rvi)
+ set_current_def (var, NULL_TREE);
+}
+
+
+/* Deallocate internal data structures used by the renamer. */
+
+static void
+fini_ssa_renamer (void)
+{
+ if (def_blocks)
+ {
+ htab_delete (def_blocks);
+ def_blocks = NULL;
+ }
+
+ cfun->gimple_df->in_ssa_p = true;
+}
+
+
+/* Main entry point into the SSA builder. The renaming process
+ proceeds in four main phases:
+
+ 1- Compute dominance frontier and immediate dominators, needed to
+ insert PHI nodes and rename the function in dominator tree
+ order.
+
+ 2- Find and mark all the blocks that define variables
+ (mark_def_site_blocks).
+
+ 3- Insert PHI nodes at dominance frontiers (insert_phi_nodes).
+
+ 4- Rename all the blocks (rewrite_blocks) and statements in the program.
+
+ Steps 3 and 4 are done using the dominator tree walker
+ (walk_dominator_tree). */
+
+static unsigned int
+rewrite_into_ssa (void)
+{
+ bitmap *dfs;
+ basic_block bb;
+ sbitmap interesting_blocks;
+
+ timevar_push (TV_TREE_SSA_OTHER);
+
+ /* Initialize operand data structures. */
+ init_ssa_operands ();
+
+ /* Initialize internal data needed by the renamer. */
+ init_ssa_renamer ();
+
+ /* Initialize the set of interesting blocks. The callback
+ mark_def_sites will add to this set those blocks that the renamer
+ should process. */
+ interesting_blocks = sbitmap_alloc (last_basic_block);
+ sbitmap_zero (interesting_blocks);
+
+ /* Initialize dominance frontier. */
+ dfs = XNEWVEC (bitmap, last_basic_block);
+ FOR_EACH_BB (bb)
+ dfs[bb->index] = BITMAP_ALLOC (NULL);
+
+ /* 1- Compute dominance frontiers. */
+ calculate_dominance_info (CDI_DOMINATORS);
+ compute_dominance_frontiers (dfs);
+
+ /* 2- Find and mark definition sites. */
+ mark_def_site_blocks (interesting_blocks);
+
+ /* 3- Insert PHI nodes at dominance frontiers of definition blocks. */
+ insert_phi_nodes (dfs);
+
+ /* 4- Rename all the blocks. */
+ rewrite_blocks (ENTRY_BLOCK_PTR, REWRITE_ALL, interesting_blocks);
+
+ /* Free allocated memory. */
+ FOR_EACH_BB (bb)
+ BITMAP_FREE (dfs[bb->index]);
+ free (dfs);
+ sbitmap_free (interesting_blocks);
+
+ fini_ssa_renamer ();
+
+ timevar_pop (TV_TREE_SSA_OTHER);
+ return 0;
+}
+
+
+struct gimple_opt_pass pass_build_ssa =
+{
+ {
+ GIMPLE_PASS,
+ "ssa", /* name */
+ NULL, /* gate */
+ rewrite_into_ssa, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ 0, /* tv_id */
+ PROP_cfg | PROP_referenced_vars, /* properties_required */
+ PROP_ssa, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_dump_func
+ | TODO_verify_ssa
+ | TODO_remove_unused_locals /* todo_flags_finish */
+ }
+};
+
+
+/* Mark the definition of VAR at STMT and BB as interesting for the
+ renamer. BLOCKS is the set of blocks that need updating. */
+
+static void
+mark_def_interesting (tree var, tree stmt, basic_block bb, bool insert_phi_p)
+{
+ gcc_assert (bitmap_bit_p (blocks_to_update, bb->index));
+ REGISTER_DEFS_IN_THIS_STMT (stmt) = 1;
+
+ if (insert_phi_p)
+ {
+ bool is_phi_p = TREE_CODE (stmt) == PHI_NODE;
+
+ set_def_block (var, bb, is_phi_p);
+
+ /* If VAR is an SSA name in NEW_SSA_NAMES, this is a definition
+ site for both itself and all the old names replaced by it. */
+ if (TREE_CODE (var) == SSA_NAME && is_new_name (var))
+ {
+ bitmap_iterator bi;
+ unsigned i;
+ bitmap set = names_replaced_by (var);
+ if (set)
+ EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi)
+ set_def_block (ssa_name (i), bb, is_phi_p);
+ }
+ }
+}
+
+
+/* Mark the use of VAR at STMT and BB as interesting for the
+ renamer. INSERT_PHI_P is true if we are going to insert new PHI
+ nodes. */
+
+static inline void
+mark_use_interesting (tree var, tree stmt, basic_block bb, bool insert_phi_p)
+{
+ basic_block def_bb = bb_for_stmt (stmt);
+
+ mark_block_for_update (def_bb);
+ mark_block_for_update (bb);
+
+ if (TREE_CODE (stmt) == PHI_NODE)
+ mark_phi_for_rewrite (def_bb, stmt);
+ else
+ REWRITE_THIS_STMT (stmt) = 1;
+
+ /* If VAR has not been defined in BB, then it is live-on-entry
+ to BB. Note that we cannot just use the block holding VAR's
+ definition because if VAR is one of the names in OLD_SSA_NAMES,
+ it will have several definitions (itself and all the names that
+ replace it). */
+ if (insert_phi_p)
+ {
+ struct def_blocks_d *db_p = get_def_blocks_for (var);
+ if (!bitmap_bit_p (db_p->def_blocks, bb->index))
+ set_livein_block (var, bb);
+ }
+}
+
+
+/* Do a dominator walk starting at BB processing statements that
+ reference symbols in SYMS_TO_RENAME. This is very similar to
+ mark_def_sites, but the scan handles statements whose operands may
+ already be SSA names.
+
+ If INSERT_PHI_P is true, mark those uses as live in the
+ corresponding block. This is later used by the PHI placement
+ algorithm to make PHI pruning decisions.
+
+ FIXME. Most of this would be unnecessary if we could associate a
+ symbol to all the SSA names that reference it. But that
+ sounds like it would be expensive to maintain. Still, it
+ would be interesting to see if it makes better sense to do
+ that. */
+
+static void
+prepare_block_for_update (basic_block bb, bool insert_phi_p)
+{
+ basic_block son;
+ block_stmt_iterator si;
+ tree phi;
+ edge e;
+ edge_iterator ei;
+
+ mark_block_for_update (bb);
+
+ /* Process PHI nodes marking interesting those that define or use
+ the symbols that we are interested in. */
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ {
+ tree lhs_sym, lhs = PHI_RESULT (phi);
+
+ lhs_sym = DECL_P (lhs) ? lhs : SSA_NAME_VAR (lhs);
+
+ if (!symbol_marked_for_renaming (lhs_sym))
+ continue;
+ mark_def_interesting (lhs_sym, phi, bb, insert_phi_p);
+
+ /* Mark the uses in phi nodes as interesting. It would be more correct
+ to process the arguments of the phi nodes of the successor edges of
+ BB at the end of prepare_block_for_update, however, that turns out
+ to be significantly more expensive. Doing it here is conservatively
+ correct -- it may only cause us to believe a value to be live in a
+ block that also contains its definition, and thus insert a few more
+ phi nodes for it. */
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ mark_use_interesting (lhs_sym, phi, e->src, insert_phi_p);
+ }
+ }
+
+ /* Process the statements. */
+ for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+ {
+ tree stmt;
+ ssa_op_iter i;
+ use_operand_p use_p;
+ def_operand_p def_p;
+
+ stmt = bsi_stmt (si);
+
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, i, SSA_OP_ALL_USES)
+ {
+ tree use = USE_FROM_PTR (use_p);
+ tree sym = DECL_P (use) ? use : SSA_NAME_VAR (use);
+ if (symbol_marked_for_renaming (sym))
+ mark_use_interesting (sym, stmt, bb, insert_phi_p);
+ }
+
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, i, SSA_OP_ALL_DEFS)
+ {
+ tree def = DEF_FROM_PTR (def_p);
+ tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def);
+ if (symbol_marked_for_renaming (sym))
+ mark_def_interesting (sym, stmt, bb, insert_phi_p);
+ }
+ }
+
+ /* Now visit all the blocks dominated by BB. */
+ for (son = first_dom_son (CDI_DOMINATORS, bb);
+ son;
+ son = next_dom_son (CDI_DOMINATORS, son))
+ prepare_block_for_update (son, insert_phi_p);
+}
+
+
+/* Helper for prepare_names_to_update. Mark all the use sites for
+ NAME as interesting. BLOCKS and INSERT_PHI_P are as in
+ prepare_names_to_update. */
+
+static void
+prepare_use_sites_for (tree name, bool insert_phi_p)
+{
+ use_operand_p use_p;
+ imm_use_iterator iter;
+
+ FOR_EACH_IMM_USE_FAST (use_p, iter, name)
+ {
+ tree stmt = USE_STMT (use_p);
+ basic_block bb = bb_for_stmt (stmt);
+
+ if (TREE_CODE (stmt) == PHI_NODE)
+ {
+ int ix = PHI_ARG_INDEX_FROM_USE (use_p);
+ edge e = PHI_ARG_EDGE (stmt, ix);
+ mark_use_interesting (name, stmt, e->src, insert_phi_p);
+ }
+ else
+ {
+ /* For regular statements, mark this as an interesting use
+ for NAME. */
+ mark_use_interesting (name, stmt, bb, insert_phi_p);
+ }
+ }
+}
+
+
+/* Helper for prepare_names_to_update. Mark the definition site for
+ NAME as interesting. BLOCKS and INSERT_PHI_P are as in
+ prepare_names_to_update. */
+
+static void
+prepare_def_site_for (tree name, bool insert_phi_p)
+{
+ tree stmt;
+ basic_block bb;
+
+ gcc_assert (names_to_release == NULL
+ || !bitmap_bit_p (names_to_release, SSA_NAME_VERSION (name)));
+
+ stmt = SSA_NAME_DEF_STMT (name);
+ bb = bb_for_stmt (stmt);
+ if (bb)
+ {
+ gcc_assert (bb->index < last_basic_block);
+ mark_block_for_update (bb);
+ mark_def_interesting (name, stmt, bb, insert_phi_p);
+ }
+}
+
+
+/* Mark definition and use sites of names in NEW_SSA_NAMES and
+ OLD_SSA_NAMES. INSERT_PHI_P is true if the caller wants to insert
+ PHI nodes for newly created names. */
+
+static void
+prepare_names_to_update (bool insert_phi_p)
+{
+ unsigned i = 0;
+ bitmap_iterator bi;
+ sbitmap_iterator sbi;
+
+ /* If a name N from NEW_SSA_NAMES is also marked to be released,
+ remove it from NEW_SSA_NAMES so that we don't try to visit its
+ defining basic block (which most likely doesn't exist). Notice
+ that we cannot do the same with names in OLD_SSA_NAMES because we
+ want to replace existing instances. */
+ if (names_to_release)
+ EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi)
+ RESET_BIT (new_ssa_names, i);
+
+ /* First process names in NEW_SSA_NAMES. Otherwise, uses of old
+ names may be considered to be live-in on blocks that contain
+ definitions for their replacements. */
+ EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi)
+ prepare_def_site_for (ssa_name (i), insert_phi_p);
+
+ /* If an old name is in NAMES_TO_RELEASE, we cannot remove it from
+ OLD_SSA_NAMES, but we have to ignore its definition site. */
+ EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi)
+ {
+ if (names_to_release == NULL || !bitmap_bit_p (names_to_release, i))
+ prepare_def_site_for (ssa_name (i), insert_phi_p);
+ prepare_use_sites_for (ssa_name (i), insert_phi_p);
+ }
+}
+
+
+/* Dump all the names replaced by NAME to FILE. */
+
+void
+dump_names_replaced_by (FILE *file, tree name)
+{
+ unsigned i;
+ bitmap old_set;
+ bitmap_iterator bi;
+
+ print_generic_expr (file, name, 0);
+ fprintf (file, " -> { ");
+
+ old_set = names_replaced_by (name);
+ EXECUTE_IF_SET_IN_BITMAP (old_set, 0, i, bi)
+ {
+ print_generic_expr (file, ssa_name (i), 0);
+ fprintf (file, " ");
+ }
+
+ fprintf (file, "}\n");
+}
+
+
+/* Dump all the names replaced by NAME to stderr. */
+
+void
+debug_names_replaced_by (tree name)
+{
+ dump_names_replaced_by (stderr, name);
+}
+
+
+/* Dump SSA update information to FILE. */
+
+void
+dump_update_ssa (FILE *file)
+{
+ unsigned i = 0;
+ bitmap_iterator bi;
+
+ if (!need_ssa_update_p ())
+ return;
+
+ if (new_ssa_names && sbitmap_first_set_bit (new_ssa_names) >= 0)
+ {
+ sbitmap_iterator sbi;
+
+ fprintf (file, "\nSSA replacement table\n");
+ fprintf (file, "N_i -> { O_1 ... O_j } means that N_i replaces "
+ "O_1, ..., O_j\n\n");
+
+ EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi)
+ dump_names_replaced_by (file, ssa_name (i));
+
+ fprintf (file, "\n");
+ fprintf (file, "Number of virtual NEW -> OLD mappings: %7u\n",
+ update_ssa_stats.num_virtual_mappings);
+ fprintf (file, "Number of real NEW -> OLD mappings: %7u\n",
+ update_ssa_stats.num_total_mappings
+ - update_ssa_stats.num_virtual_mappings);
+ fprintf (file, "Number of total NEW -> OLD mappings: %7u\n",
+ update_ssa_stats.num_total_mappings);
+
+ fprintf (file, "\nNumber of virtual symbols: %u\n",
+ update_ssa_stats.num_virtual_symbols);
+ }
+
+ if (syms_to_rename && !bitmap_empty_p (syms_to_rename))
+ {
+ fprintf (file, "\n\nSymbols to be put in SSA form\n\n");
+ dump_decl_set (file, syms_to_rename);
+ }
+
+ if (names_to_release && !bitmap_empty_p (names_to_release))
+ {
+ fprintf (file, "\n\nSSA names to release after updating the SSA web\n\n");
+ EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi)
+ {
+ print_generic_expr (file, ssa_name (i), 0);
+ fprintf (file, " ");
+ }
+ }
+
+ fprintf (file, "\n\n");
+}
+
+
+/* Dump SSA update information to stderr. */
+
+void
+debug_update_ssa (void)
+{
+ dump_update_ssa (stderr);
+}
+
+
+/* Initialize data structures used for incremental SSA updates. */
+
+static void
+init_update_ssa (void)
+{
+ /* Reserve more space than the current number of names. The calls to
+ add_new_name_mapping are typically done after creating new SSA
+ names, so we'll need to reallocate these arrays. */
+ old_ssa_names = sbitmap_alloc (num_ssa_names + NAME_SETS_GROWTH_FACTOR);
+ sbitmap_zero (old_ssa_names);
+
+ new_ssa_names = sbitmap_alloc (num_ssa_names + NAME_SETS_GROWTH_FACTOR);
+ sbitmap_zero (new_ssa_names);
+
+ repl_tbl = htab_create (20, repl_map_hash, repl_map_eq, repl_map_free);
+ need_to_initialize_update_ssa_p = false;
+ need_to_update_vops_p = false;
+ syms_to_rename = BITMAP_ALLOC (NULL);
+ regs_to_rename = BITMAP_ALLOC (NULL);
+ mem_syms_to_rename = BITMAP_ALLOC (NULL);
+ names_to_release = NULL;
+ memset (&update_ssa_stats, 0, sizeof (update_ssa_stats));
+ update_ssa_stats.virtual_symbols = BITMAP_ALLOC (NULL);
+}
+
+
+/* Deallocate data structures used for incremental SSA updates. */
+
+void
+delete_update_ssa (void)
+{
+ unsigned i;
+ bitmap_iterator bi;
+
+ sbitmap_free (old_ssa_names);
+ old_ssa_names = NULL;
+
+ sbitmap_free (new_ssa_names);
+ new_ssa_names = NULL;
+
+ htab_delete (repl_tbl);
+ repl_tbl = NULL;
+
+ need_to_initialize_update_ssa_p = true;
+ need_to_update_vops_p = false;
+ BITMAP_FREE (syms_to_rename);
+ BITMAP_FREE (regs_to_rename);
+ BITMAP_FREE (mem_syms_to_rename);
+ BITMAP_FREE (update_ssa_stats.virtual_symbols);
+
+ if (names_to_release)
+ {
+ EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi)
+ release_ssa_name (ssa_name (i));
+ BITMAP_FREE (names_to_release);
+ }
+
+ clear_ssa_name_info ();
+
+ fini_ssa_renamer ();
+
+ if (blocks_with_phis_to_rewrite)
+ EXECUTE_IF_SET_IN_BITMAP (blocks_with_phis_to_rewrite, 0, i, bi)
+ {
+ tree_vec phis = VEC_index (tree_vec, phis_to_rewrite, i);
+
+ VEC_free (tree, heap, phis);
+ VEC_replace (tree_vec, phis_to_rewrite, i, NULL);
+ }
+
+ BITMAP_FREE (blocks_with_phis_to_rewrite);
+ BITMAP_FREE (blocks_to_update);
+}
+
+
+/* Create a new name for OLD_NAME in statement STMT and replace the
+ operand pointed to by DEF_P with the newly created name. Return
+ the new name and register the replacement mapping <NEW, OLD> in
+ update_ssa's tables. */
+
+tree
+create_new_def_for (tree old_name, tree stmt, def_operand_p def)
+{
+ tree new_name = duplicate_ssa_name (old_name, stmt);
+
+ SET_DEF (def, new_name);
+
+ if (TREE_CODE (stmt) == PHI_NODE)
+ {
+ edge e;
+ edge_iterator ei;
+ basic_block bb = bb_for_stmt (stmt);
+
+ /* If needed, mark NEW_NAME as occurring in an abnormal PHI node. */
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (e->flags & EDGE_ABNORMAL)
+ {
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (new_name) = 1;
+ break;
+ }
+ }
+
+ register_new_name_mapping (new_name, old_name);
+
+ /* For the benefit of passes that will be updating the SSA form on
+ their own, set the current reaching definition of OLD_NAME to be
+ NEW_NAME. */
+ set_current_def (old_name, new_name);
+
+ return new_name;
+}
+
+
+/* Register name NEW to be a replacement for name OLD. This function
+ must be called for every replacement that should be performed by
+ update_ssa. */
+
+void
+register_new_name_mapping (tree new, tree old)
+{
+ if (need_to_initialize_update_ssa_p)
+ init_update_ssa ();
+
+ add_new_name_mapping (new, old);
+}
+
+
+/* Register symbol SYM to be renamed by update_ssa. */
+
+void
+mark_sym_for_renaming (tree sym)
+{
+ if (need_to_initialize_update_ssa_p)
+ init_update_ssa ();
+
+ bitmap_set_bit (syms_to_rename, DECL_UID (sym));
+
+ if (!is_gimple_reg (sym))
+ {
+ need_to_update_vops_p = true;
+ if (memory_partition (sym))
+ bitmap_set_bit (syms_to_rename, DECL_UID (memory_partition (sym)));
+ }
+}
+
+
+/* Register all the symbols in SET to be renamed by update_ssa. */
void
-debug_def_blocks (void)
+mark_set_for_renaming (bitmap set)
{
- htab_traverse (def_blocks, debug_def_blocks_r, NULL);
-}
+ bitmap_iterator bi;
+ unsigned i;
-/* Callback for htab_traverse to dump the DEF_BLOCKS hash table. */
+ if (set == NULL || bitmap_empty_p (set))
+ return;
-static int
-debug_def_blocks_r (void **slot, void *data ATTRIBUTE_UNUSED)
-{
- unsigned long i;
- struct def_blocks_d *db_p = (struct def_blocks_d *) *slot;
-
- fprintf (stderr, "VAR: ");
- print_generic_expr (stderr, db_p->var, dump_flags);
- fprintf (stderr, ", DEF_BLOCKS: { ");
- EXECUTE_IF_SET_IN_BITMAP (db_p->def_blocks, 0, i,
- fprintf (stderr, "%ld ", i));
- fprintf (stderr, "}");
- fprintf (stderr, ", LIVEIN_BLOCKS: { ");
- EXECUTE_IF_SET_IN_BITMAP (db_p->livein_blocks, 0, i,
- fprintf (stderr, "%ld ", i));
- fprintf (stderr, "}\n");
+ if (need_to_initialize_update_ssa_p)
+ init_update_ssa ();
- return 1;
+ EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi)
+ mark_sym_for_renaming (referenced_var (i));
}
-/* Return the set of blocks where variable VAR is defined and the blocks
- where VAR is live on entry (livein). Return NULL, if no entry is
- found in DEF_BLOCKS. */
+/* Return true if there is any work to be done by update_ssa. */
-static inline struct def_blocks_d *
-find_def_blocks_for (tree var)
+bool
+need_ssa_update_p (void)
{
- struct def_blocks_d dm;
- dm.var = var;
- return (struct def_blocks_d *) htab_find (def_blocks, &dm);
+ return syms_to_rename || old_ssa_names || new_ssa_names;
}
+/* Return true if SSA name mappings have been registered for SSA updating. */
-/* Return the set of blocks where variable VAR is defined and the blocks
- where VAR is live on entry (livein). If no entry is found in
- DEF_BLOCKS, a new one is created and returned. */
-
-static inline struct def_blocks_d *
-get_def_blocks_for (tree var)
+bool
+name_mappings_registered_p (void)
{
- struct def_blocks_d db, *db_p;
- void **slot;
+ return repl_tbl && htab_elements (repl_tbl) > 0;
+}
- db.var = var;
- slot = htab_find_slot (def_blocks, (void *) &db, INSERT);
- if (*slot == NULL)
- {
- db_p = xmalloc (sizeof (*db_p));
- db_p->var = var;
- db_p->def_blocks = BITMAP_XMALLOC ();
- db_p->phi_blocks = BITMAP_XMALLOC ();
- db_p->livein_blocks = BITMAP_XMALLOC ();
- *slot = (void *) db_p;
- }
- else
- db_p = (struct def_blocks_d *) *slot;
+/* Return true if name N has been registered in the replacement table. */
- return db_p;
-}
+bool
+name_registered_for_update_p (tree n)
+{
+ if (!need_ssa_update_p ())
+ return false;
-/* If a variable V in VARS_TO_RENAME is a pointer, the renaming
- process will cause us to lose the name memory tags that may have
- been associated with the various SSA_NAMEs of V. This means that
- the variables aliased to those name tags also need to be renamed
- again.
+ return is_new_name (n)
+ || is_old_name (n)
+ || symbol_marked_for_renaming (SSA_NAME_VAR (n));
+}
- FIXME 1- We should either have a better scheme for renaming
- pointers that doesn't lose name tags or re-run alias
- analysis to recover points-to information.
- 2- Currently we just invalidate *all* the name tags. This
- should be more selective. */
+/* Return the set of all the SSA names marked to be replaced. */
-static void
-invalidate_name_tags (bitmap vars_to_rename)
+bitmap
+ssa_names_to_replace (void)
{
- size_t i;
- bool rename_name_tags_p;
+ unsigned i = 0;
+ bitmap ret;
+ sbitmap_iterator sbi;
+
+ ret = BITMAP_ALLOC (NULL);
+ EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi)
+ bitmap_set_bit (ret, i);
- rename_name_tags_p = false;
- EXECUTE_IF_SET_IN_BITMAP (vars_to_rename, 0, i,
- if (POINTER_TYPE_P (TREE_TYPE (referenced_var (i))))
- {
- rename_name_tags_p = true;
- break;
- });
+ return ret;
+}
- if (rename_name_tags_p)
- for (i = 0; i < num_referenced_vars; i++)
- {
- var_ann_t ann = var_ann (referenced_var (i));
- if (ann->mem_tag_kind == NAME_TAG)
- {
- size_t j;
- varray_type may_aliases = ann->may_aliases;
-
- bitmap_set_bit (vars_to_rename, ann->uid);
- if (ann->may_aliases)
- for (j = 0; j < VARRAY_ACTIVE_SIZE (may_aliases); j++)
- {
- tree var = VARRAY_TREE (may_aliases, j);
- bitmap_set_bit (vars_to_rename, var_ann (var)->uid);
- }
- }
- }
-}
+/* Mark NAME to be released after update_ssa has finished. */
+void
+release_ssa_name_after_update_ssa (tree name)
+{
+ gcc_assert (!need_to_initialize_update_ssa_p);
-/* Main entry point into the SSA builder. The renaming process
- proceeds in five main phases:
+ if (names_to_release == NULL)
+ names_to_release = BITMAP_ALLOC (NULL);
- 1- If VARS_TO_RENAME has any entries, any existing PHI nodes for
- those variables are removed from the flow graph so that they can
- be computed again.
+ bitmap_set_bit (names_to_release, SSA_NAME_VERSION (name));
+}
- 2- Compute dominance frontier and immediate dominators, needed to
- insert PHI nodes and rename the function in dominator tree
- order.
- 3- Find and mark all the blocks that define variables
- (mark_def_sites).
+/* Insert new PHI nodes to replace VAR. DFS contains dominance
+ frontier information. BLOCKS is the set of blocks to be updated.
- 4- Insert PHI nodes at dominance frontiers (insert_phi_nodes).
+ This is slightly different than the regular PHI insertion
+ algorithm. The value of UPDATE_FLAGS controls how PHI nodes for
+ real names (i.e., GIMPLE registers) are inserted:
+
+ - If UPDATE_FLAGS == TODO_update_ssa, we are only interested in PHI
+ nodes inside the region affected by the block that defines VAR
+ and the blocks that define all its replacements. All these
+ definition blocks are stored in DEF_BLOCKS[VAR]->DEF_BLOCKS.
- 5- Rename all the blocks (rewrite_initialize_block,
- rewrite_add_phi_arguments) and statements in the program
- (rewrite_stmt).
+ First, we compute the entry point to the region (ENTRY). This is
+ given by the nearest common dominator to all the definition
+ blocks. When computing the iterated dominance frontier (IDF), any
+ block not strictly dominated by ENTRY is ignored.
- Steps 3 and 5 are done using the dominator tree walker
- (walk_dominator_tree).
+ We then call the standard PHI insertion algorithm with the pruned
+ IDF.
- ALL is true if all variables should be renamed (otherwise just those
- mentioned in vars_to_rename are taken into account). */
+ - If UPDATE_FLAGS == TODO_update_ssa_full_phi, the IDF for real
+ names is not pruned. PHI nodes are inserted at every IDF block. */
-void
-rewrite_into_ssa (bool all)
+static void
+insert_updated_phi_nodes_for (tree var, bitmap *dfs, bitmap blocks,
+ unsigned update_flags)
{
- bitmap *dfs;
- basic_block bb;
- struct dom_walk_data walk_data;
- struct mark_def_sites_global_data mark_def_sites_global_data;
- bitmap old_vars_to_rename = vars_to_rename;
+ basic_block entry;
+ struct def_blocks_d *db;
+ bitmap idf, pruned_idf;
+ bitmap_iterator bi;
unsigned i;
-
- timevar_push (TV_TREE_SSA_OTHER);
- if (all)
- vars_to_rename = NULL;
+#if defined ENABLE_CHECKING
+ if (TREE_CODE (var) == SSA_NAME)
+ gcc_assert (is_old_name (var));
else
- {
- /* Initialize the array of variables to rename. */
- gcc_assert (vars_to_rename);
+ gcc_assert (symbol_marked_for_renaming (var));
+#endif
- if (bitmap_first_set_bit (vars_to_rename) < 0)
- {
- timevar_pop (TV_TREE_SSA_OTHER);
- return;
- }
-
- invalidate_name_tags (vars_to_rename);
+ /* Get all the definition sites for VAR. */
+ db = find_def_blocks_for (var);
- /* Now remove all the existing PHI nodes (if any) for the variables
- that we are about to rename into SSA. */
- remove_all_phi_nodes_for (vars_to_rename);
- }
+ /* No need to do anything if there were no definitions to VAR. */
+ if (db == NULL || bitmap_empty_p (db->def_blocks))
+ return;
- /* Allocate memory for the DEF_BLOCKS hash table. */
- def_blocks = htab_create (VARRAY_ACTIVE_SIZE (referenced_vars),
- def_blocks_hash, def_blocks_eq, def_blocks_free);
+ /* Compute the initial iterated dominance frontier. */
+ idf = compute_idf (db->def_blocks, dfs);
+ pruned_idf = BITMAP_ALLOC (NULL);
- /* Initialize dominance frontier and immediate dominator bitmaps.
- Also count the number of predecessors for each block. Doing so
- can save significant time during PHI insertion for large graphs. */
- dfs = (bitmap *) xmalloc (last_basic_block * sizeof (bitmap *));
- FOR_EACH_BB (bb)
+ if (TREE_CODE (var) == SSA_NAME)
{
- edge e;
- int count = 0;
-
- for (e = bb->pred; e; e = e->pred_next)
- count++;
-
- bb_ann (bb)->num_preds = count;
- dfs[bb->index] = BITMAP_XMALLOC ();
+ if (update_flags == TODO_update_ssa)
+ {
+ /* If doing regular SSA updates for GIMPLE registers, we are
+ only interested in IDF blocks dominated by the nearest
+ common dominator of all the definition blocks. */
+ entry = nearest_common_dominator_for_set (CDI_DOMINATORS,
+ db->def_blocks);
+ if (entry != ENTRY_BLOCK_PTR)
+ EXECUTE_IF_SET_IN_BITMAP (idf, 0, i, bi)
+ if (BASIC_BLOCK (i) != entry
+ && dominated_by_p (CDI_DOMINATORS, BASIC_BLOCK (i), entry))
+ bitmap_set_bit (pruned_idf, i);
+ }
+ else
+ {
+ /* Otherwise, do not prune the IDF for VAR. */
+ gcc_assert (update_flags == TODO_update_ssa_full_phi);
+ bitmap_copy (pruned_idf, idf);
+ }
+ }
+ else
+ {
+ /* Otherwise, VAR is a symbol that needs to be put into SSA form
+ for the first time, so we need to compute the full IDF for
+ it. */
+ bitmap_copy (pruned_idf, idf);
}
- for (i = 0; i < num_referenced_vars; i++)
- set_current_def (referenced_var (i), NULL_TREE);
-
- /* Ensure that the dominance information is OK. */
- calculate_dominance_info (CDI_DOMINATORS);
-
- /* Compute dominance frontiers. */
- compute_dominance_frontiers (dfs);
+ if (!bitmap_empty_p (pruned_idf))
+ {
+ /* Make sure that PRUNED_IDF blocks and all their feeding blocks
+ are included in the region to be updated. The feeding blocks
+ are important to guarantee that the PHI arguments are renamed
+ properly. */
+
+ /* FIXME, this is not needed if we are updating symbols. We are
+ already starting at the ENTRY block anyway. */
+ bitmap_ior_into (blocks, pruned_idf);
+ EXECUTE_IF_SET_IN_BITMAP (pruned_idf, 0, i, bi)
+ {
+ edge e;
+ edge_iterator ei;
+ basic_block bb = BASIC_BLOCK (i);
- /* Setup callbacks for the generic dominator tree walker to find and
- mark definition sites. */
- walk_data.walk_stmts_backward = false;
- walk_data.dom_direction = CDI_DOMINATORS;
- walk_data.initialize_block_local_data = NULL;
- walk_data.before_dom_children_before_stmts = mark_def_sites_initialize_block;
- walk_data.before_dom_children_walk_stmts = mark_def_sites;
- walk_data.before_dom_children_after_stmts = NULL;
- walk_data.after_dom_children_before_stmts = NULL;
- walk_data.after_dom_children_walk_stmts = NULL;
- walk_data.after_dom_children_after_stmts = NULL;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (e->src->index >= 0)
+ bitmap_set_bit (blocks, e->src->index);
+ }
- /* Notice that this bitmap is indexed using variable UIDs, so it must be
- large enough to accommodate all the variables referenced in the
- function, not just the ones we are renaming. */
- mark_def_sites_global_data.kills = sbitmap_alloc (num_referenced_vars);
- walk_data.global_data = &mark_def_sites_global_data;
+ insert_phi_nodes_for (var, pruned_idf, true);
+ }
- /* We do not have any local data. */
- walk_data.block_local_data_size = 0;
+ BITMAP_FREE (pruned_idf);
+ BITMAP_FREE (idf);
+}
- /* Initialize the dominator walker. */
- init_walk_dominator_tree (&walk_data);
- /* Recursively walk the dominator tree. */
- walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
+/* Heuristic to determine whether SSA name mappings for virtual names
+ should be discarded and their symbols rewritten from scratch. When
+ there is a large number of mappings for virtual names, the
+ insertion of PHI nodes for the old names in the mappings takes
+ considerable more time than if we inserted PHI nodes for the
+ symbols instead.
- /* Finalize the dominator walker. */
- fini_walk_dominator_tree (&walk_data);
+ Currently the heuristic takes these stats into account:
- /* We no longer need this bitmap, clear and free it. */
- sbitmap_free (mark_def_sites_global_data.kills);
+ - Number of mappings for virtual SSA names.
+ - Number of distinct virtual symbols involved in those mappings.
- /* Insert PHI nodes at dominance frontiers of definition blocks. */
- insert_phi_nodes (dfs, NULL);
+ If the number of virtual mappings is much larger than the number of
+ virtual symbols, then it will be faster to compute PHI insertion
+ spots for the symbols. Even if this involves traversing the whole
+ CFG, which is what happens when symbols are renamed from scratch. */
- /* Rewrite all the basic blocks in the program. */
- timevar_push (TV_TREE_SSA_REWRITE_BLOCKS);
+static bool
+switch_virtuals_to_full_rewrite_p (void)
+{
+ if (update_ssa_stats.num_virtual_mappings < (unsigned) MIN_VIRTUAL_MAPPINGS)
+ return false;
- /* Setup callbacks for the generic dominator tree walker. */
- walk_data.walk_stmts_backward = false;
- walk_data.dom_direction = CDI_DOMINATORS;
- walk_data.initialize_block_local_data = rewrite_initialize_block_local_data;
- walk_data.before_dom_children_before_stmts = rewrite_initialize_block;
- walk_data.before_dom_children_walk_stmts = rewrite_stmt;
- walk_data.before_dom_children_after_stmts = rewrite_add_phi_arguments;
- walk_data.after_dom_children_before_stmts = NULL;
- walk_data.after_dom_children_walk_stmts = NULL;
- walk_data.after_dom_children_after_stmts = rewrite_finalize_block;
- walk_data.global_data = NULL;
- walk_data.block_local_data_size = sizeof (struct rewrite_block_data);
+ if (update_ssa_stats.num_virtual_mappings
+ > (unsigned) VIRTUAL_MAPPINGS_TO_SYMS_RATIO
+ * update_ssa_stats.num_virtual_symbols)
+ return true;
- /* Initialize the dominator walker. */
- init_walk_dominator_tree (&walk_data);
+ return false;
+}
- /* Recursively walk the dominator tree rewriting each statement in
- each basic block. */
- walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
- /* Finalize the dominator walker. */
- fini_walk_dominator_tree (&walk_data);
+/* Remove every virtual mapping and mark all the affected virtual
+ symbols for renaming. */
- timevar_pop (TV_TREE_SSA_REWRITE_BLOCKS);
+static void
+switch_virtuals_to_full_rewrite (void)
+{
+ unsigned i = 0;
+ sbitmap_iterator sbi;
- /* Debugging dumps. */
- if (dump_file && (dump_flags & TDF_STATS))
+ if (dump_file)
{
- dump_dfa_stats (dump_file);
- dump_tree_ssa_stats (dump_file);
+ fprintf (dump_file, "\nEnabled virtual name mapping heuristic.\n");
+ fprintf (dump_file, "\tNumber of virtual mappings: %7u\n",
+ update_ssa_stats.num_virtual_mappings);
+ fprintf (dump_file, "\tNumber of unique virtual symbols: %7u\n",
+ update_ssa_stats.num_virtual_symbols);
+ fprintf (dump_file, "Updating FUD-chains from top of CFG will be "
+ "faster than processing\nthe name mappings.\n\n");
}
- /* Free allocated memory. */
- FOR_EACH_BB (bb)
- BITMAP_XFREE (dfs[bb->index]);
- free (dfs);
+ /* Remove all virtual names from NEW_SSA_NAMES and OLD_SSA_NAMES.
+ Note that it is not really necessary to remove the mappings from
+ REPL_TBL, that would only waste time. */
+ EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi)
+ if (!is_gimple_reg (ssa_name (i)))
+ RESET_BIT (new_ssa_names, i);
- htab_delete (def_blocks);
+ EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi)
+ if (!is_gimple_reg (ssa_name (i)))
+ RESET_BIT (old_ssa_names, i);
- vars_to_rename = old_vars_to_rename;
- timevar_pop (TV_TREE_SSA_OTHER);
+ mark_set_for_renaming (update_ssa_stats.virtual_symbols);
}
-/* The marked ssa names may have more than one definition;
- add phi nodes and rewrite them to fix this. */
+
+/* Given a set of newly created SSA names (NEW_SSA_NAMES) and a set of
+ existing SSA names (OLD_SSA_NAMES), update the SSA form so that:
+
+ 1- The names in OLD_SSA_NAMES dominated by the definitions of
+ NEW_SSA_NAMES are all re-written to be reached by the
+ appropriate definition from NEW_SSA_NAMES.
+
+ 2- If needed, new PHI nodes are added to the iterated dominance
+ frontier of the blocks where each of NEW_SSA_NAMES are defined.
+
+ The mapping between OLD_SSA_NAMES and NEW_SSA_NAMES is setup by
+ calling register_new_name_mapping for every pair of names that the
+ caller wants to replace.
+
+ The caller identifies the new names that have been inserted and the
+ names that need to be replaced by calling register_new_name_mapping
+ for every pair <NEW, OLD>. Note that the function assumes that the
+ new names have already been inserted in the IL.
+
+ For instance, given the following code:
+
+ 1 L0:
+ 2 x_1 = PHI (0, x_5)
+ 3 if (x_1 < 10)
+ 4 if (x_1 > 7)
+ 5 y_2 = 0
+ 6 else
+ 7 y_3 = x_1 + x_7
+ 8 endif
+ 9 x_5 = x_1 + 1
+ 10 goto L0;
+ 11 endif
+
+ Suppose that we insert new names x_10 and x_11 (lines 4 and 8).
+
+ 1 L0:
+ 2 x_1 = PHI (0, x_5)
+ 3 if (x_1 < 10)
+ 4 x_10 = ...
+ 5 if (x_1 > 7)
+ 6 y_2 = 0
+ 7 else
+ 8 x_11 = ...
+ 9 y_3 = x_1 + x_7
+ 10 endif
+ 11 x_5 = x_1 + 1
+ 12 goto L0;
+ 13 endif
+
+ We want to replace all the uses of x_1 with the new definitions of
+ x_10 and x_11. Note that the only uses that should be replaced are
+ those at lines 5, 9 and 11. Also, the use of x_7 at line 9 should
+ *not* be replaced (this is why we cannot just mark symbol 'x' for
+ renaming).
+
+ Additionally, we may need to insert a PHI node at line 11 because
+ that is a merge point for x_10 and x_11. So the use of x_1 at line
+ 11 will be replaced with the new PHI node. The insertion of PHI
+ nodes is optional. They are not strictly necessary to preserve the
+ SSA form, and depending on what the caller inserted, they may not
+ even be useful for the optimizers. UPDATE_FLAGS controls various
+ aspects of how update_ssa operates, see the documentation for
+ TODO_update_ssa*. */
void
-rewrite_ssa_into_ssa (void)
+update_ssa (unsigned update_flags)
{
- bitmap *dfs;
- basic_block bb;
- struct dom_walk_data walk_data;
- struct mark_def_sites_global_data mark_def_sites_global_data;
- unsigned i;
- sbitmap snames_to_rename;
- tree name;
- bitmap to_rename;
-
- if (!any_marked_for_rewrite_p ())
+ basic_block bb, start_bb;
+ bitmap_iterator bi;
+ unsigned i = 0;
+ sbitmap tmp;
+ bool insert_phi_p;
+ sbitmap_iterator sbi;
+
+ if (!need_ssa_update_p ())
return;
- to_rename = marked_ssa_names ();
- timevar_push (TV_TREE_SSA_OTHER);
+ timevar_push (TV_TREE_SSA_INCREMENTAL);
- /* Allocate memory for the DEF_BLOCKS hash table. */
- def_blocks = htab_create (num_ssa_names,
- def_blocks_hash, def_blocks_eq, def_blocks_free);
+ blocks_with_phis_to_rewrite = BITMAP_ALLOC (NULL);
+ if (!phis_to_rewrite)
+ phis_to_rewrite = VEC_alloc (tree_vec, heap, last_basic_block);
+ blocks_to_update = BITMAP_ALLOC (NULL);
- /* Initialize dominance frontier and immediate dominator bitmaps.
- Also count the number of predecessors for each block. Doing so
- can save significant time during PHI insertion for large graphs. */
- dfs = (bitmap *) xmalloc (last_basic_block * sizeof (bitmap *));
- FOR_EACH_BB (bb)
- {
- edge e;
- int count = 0;
+ /* Ensure that the dominance information is up-to-date. */
+ calculate_dominance_info (CDI_DOMINATORS);
- for (e = bb->pred; e; e = e->pred_next)
- count++;
+ /* Only one update flag should be set. */
+ gcc_assert (update_flags == TODO_update_ssa
+ || update_flags == TODO_update_ssa_no_phi
+ || update_flags == TODO_update_ssa_full_phi
+ || update_flags == TODO_update_ssa_only_virtuals);
- bb_ann (bb)->num_preds = count;
- dfs[bb->index] = BITMAP_XMALLOC ();
+ /* If we only need to update virtuals, remove all the mappings for
+ real names before proceeding. The caller is responsible for
+ having dealt with the name mappings before calling update_ssa. */
+ if (update_flags == TODO_update_ssa_only_virtuals)
+ {
+ sbitmap_zero (old_ssa_names);
+ sbitmap_zero (new_ssa_names);
+ htab_empty (repl_tbl);
}
- /* Ensure that the dominance information is OK. */
- calculate_dominance_info (CDI_DOMINATORS);
-
- /* Compute dominance frontiers. */
- compute_dominance_frontiers (dfs);
-
- /* Setup callbacks for the generic dominator tree walker to find and
- mark definition sites. */
- walk_data.walk_stmts_backward = false;
- walk_data.dom_direction = CDI_DOMINATORS;
- walk_data.initialize_block_local_data = NULL;
- walk_data.before_dom_children_before_stmts
- = ssa_mark_def_sites_initialize_block;
- walk_data.before_dom_children_walk_stmts = ssa_mark_def_sites;
- walk_data.before_dom_children_after_stmts = ssa_mark_phi_uses;
- walk_data.after_dom_children_before_stmts = NULL;
- walk_data.after_dom_children_walk_stmts = NULL;
- walk_data.after_dom_children_after_stmts = NULL;
+ insert_phi_p = (update_flags != TODO_update_ssa_no_phi);
- snames_to_rename = sbitmap_alloc (num_ssa_names);
- sbitmap_zero (snames_to_rename);
- EXECUTE_IF_SET_IN_BITMAP (to_rename, 0, i,
- SET_BIT (snames_to_rename, i));
+ if (insert_phi_p)
+ {
+ /* If the caller requested PHI nodes to be added, initialize
+ live-in information data structures (DEF_BLOCKS). */
+
+ /* For each SSA name N, the DEF_BLOCKS table describes where the
+ name is defined, which blocks have PHI nodes for N, and which
+ blocks have uses of N (i.e., N is live-on-entry in those
+ blocks). */
+ def_blocks = htab_create (num_ssa_names, def_blocks_hash,
+ def_blocks_eq, def_blocks_free);
+ }
+ else
+ {
+ def_blocks = NULL;
+ }
- mark_def_sites_global_data.kills = sbitmap_alloc (num_ssa_names);
- mark_def_sites_global_data.names_to_rename = snames_to_rename;
- walk_data.global_data = &mark_def_sites_global_data;
+ /* Heuristic to avoid massive slow downs when the replacement
+ mappings include lots of virtual names. */
+ if (insert_phi_p && switch_virtuals_to_full_rewrite_p ())
+ switch_virtuals_to_full_rewrite ();
- /* We do not have any local data. */
- walk_data.block_local_data_size = 0;
+ /* If there are symbols to rename, identify those symbols that are
+ GIMPLE registers into the set REGS_TO_RENAME and those that are
+ memory symbols into the set MEM_SYMS_TO_RENAME. */
+ if (!bitmap_empty_p (syms_to_rename))
+ {
+ unsigned i;
+ bitmap_iterator bi;
- /* Initialize the dominator walker. */
- init_walk_dominator_tree (&walk_data);
+ EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi)
+ {
+ tree sym = referenced_var (i);
+ if (is_gimple_reg (sym))
+ bitmap_set_bit (regs_to_rename, i);
+ else
+ {
+ /* Memory partitioning information may have been
+ computed after the symbol was marked for renaming,
+ if SYM is inside a partition also mark the partition
+ for renaming. */
+ tree mpt = memory_partition (sym);
+ if (mpt)
+ bitmap_set_bit (syms_to_rename, DECL_UID (mpt));
+ }
+ }
- /* Recursively walk the dominator tree. */
- walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
+ /* Memory symbols are those not in REGS_TO_RENAME. */
+ bitmap_and_compl (mem_syms_to_rename, syms_to_rename, regs_to_rename);
+ }
- /* Finalize the dominator walker. */
- fini_walk_dominator_tree (&walk_data);
+ /* If there are names defined in the replacement table, prepare
+ definition and use sites for all the names in NEW_SSA_NAMES and
+ OLD_SSA_NAMES. */
+ if (sbitmap_first_set_bit (new_ssa_names) >= 0)
+ {
+ prepare_names_to_update (insert_phi_p);
+
+ /* If all the names in NEW_SSA_NAMES had been marked for
+ removal, and there are no symbols to rename, then there's
+ nothing else to do. */
+ if (sbitmap_first_set_bit (new_ssa_names) < 0
+ && bitmap_empty_p (syms_to_rename))
+ goto done;
+ }
- /* We no longer need this bitmap, clear and free it. */
- sbitmap_free (mark_def_sites_global_data.kills);
+ /* Next, determine the block at which to start the renaming process. */
+ if (!bitmap_empty_p (syms_to_rename))
+ {
+ /* If we have to rename some symbols from scratch, we need to
+ start the process at the root of the CFG. FIXME, it should
+ be possible to determine the nearest block that had a
+ definition for each of the symbols that are marked for
+ updating. For now this seems more work than it's worth. */
+ start_bb = ENTRY_BLOCK_PTR;
+
+ /* Traverse the CFG looking for existing definitions and uses of
+ symbols in SYMS_TO_RENAME. Mark interesting blocks and
+ statements and set local live-in information for the PHI
+ placement heuristics. */
+ prepare_block_for_update (start_bb, insert_phi_p);
+ }
+ else
+ {
+ /* Otherwise, the entry block to the region is the nearest
+ common dominator for the blocks in BLOCKS. */
+ start_bb = nearest_common_dominator_for_set (CDI_DOMINATORS,
+ blocks_to_update);
+ }
- for (i = 1; i < num_ssa_names; i++)
- set_current_def (ssa_name (i), NULL_TREE);
+ /* If requested, insert PHI nodes at the iterated dominance frontier
+ of every block, creating new definitions for names in OLD_SSA_NAMES
+ and for symbols in SYMS_TO_RENAME. */
+ if (insert_phi_p)
+ {
+ bitmap *dfs;
- /* Insert PHI nodes at dominance frontiers of definition blocks. */
- insert_phi_nodes (dfs, to_rename);
+ /* If the caller requested PHI nodes to be added, compute
+ dominance frontiers. */
+ dfs = XNEWVEC (bitmap, last_basic_block);
+ FOR_EACH_BB (bb)
+ dfs[bb->index] = BITMAP_ALLOC (NULL);
+ compute_dominance_frontiers (dfs);
- /* Rewrite all the basic blocks in the program. */
- timevar_push (TV_TREE_SSA_REWRITE_BLOCKS);
+ if (sbitmap_first_set_bit (old_ssa_names) >= 0)
+ {
+ sbitmap_iterator sbi;
+
+ /* insert_update_phi_nodes_for will call add_new_name_mapping
+ when inserting new PHI nodes, so the set OLD_SSA_NAMES
+ will grow while we are traversing it (but it will not
+ gain any new members). Copy OLD_SSA_NAMES to a temporary
+ for traversal. */
+ sbitmap tmp = sbitmap_alloc (old_ssa_names->n_bits);
+ sbitmap_copy (tmp, old_ssa_names);
+ EXECUTE_IF_SET_IN_SBITMAP (tmp, 0, i, sbi)
+ insert_updated_phi_nodes_for (ssa_name (i), dfs, blocks_to_update,
+ update_flags);
+ sbitmap_free (tmp);
+ }
- /* Setup callbacks for the generic dominator tree walker. */
- walk_data.walk_stmts_backward = false;
- walk_data.dom_direction = CDI_DOMINATORS;
- walk_data.initialize_block_local_data
- = rewrite_initialize_block_local_data;
- walk_data.before_dom_children_before_stmts = ssa_rewrite_initialize_block;
- walk_data.before_dom_children_walk_stmts = ssa_rewrite_stmt;
- walk_data.before_dom_children_after_stmts = ssa_rewrite_phi_arguments;
- walk_data.after_dom_children_before_stmts = NULL;
- walk_data.after_dom_children_walk_stmts = NULL;
- walk_data.after_dom_children_after_stmts = ssa_rewrite_finalize_block;
- walk_data.global_data = snames_to_rename;
- walk_data.block_local_data_size = sizeof (struct rewrite_block_data);
+ EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi)
+ insert_updated_phi_nodes_for (referenced_var (i), dfs, blocks_to_update,
+ update_flags);
- /* Initialize the dominator walker. */
- init_walk_dominator_tree (&walk_data);
+ FOR_EACH_BB (bb)
+ BITMAP_FREE (dfs[bb->index]);
+ free (dfs);
- /* Recursively walk the dominator tree rewriting each statement in
- each basic block. */
- walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
+ /* Insertion of PHI nodes may have added blocks to the region.
+ We need to re-compute START_BB to include the newly added
+ blocks. */
+ if (start_bb != ENTRY_BLOCK_PTR)
+ start_bb = nearest_common_dominator_for_set (CDI_DOMINATORS,
+ blocks_to_update);
+ }
- /* Finalize the dominator walker. */
- fini_walk_dominator_tree (&walk_data);
+ /* Reset the current definition for name and symbol before renaming
+ the sub-graph. */
+ EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi)
+ set_current_def (ssa_name (i), NULL_TREE);
- unmark_all_for_rewrite ();
+ EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi)
+ set_current_def (referenced_var (i), NULL_TREE);
- EXECUTE_IF_SET_IN_BITMAP (to_rename, 0, i, release_ssa_name (ssa_name (i)));
+ /* Now start the renaming process at START_BB. */
+ tmp = sbitmap_alloc (last_basic_block);
+ sbitmap_zero (tmp);
+ EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi)
+ SET_BIT (tmp, i);
- sbitmap_free (snames_to_rename);
+ rewrite_blocks (start_bb, REWRITE_UPDATE, tmp);
- timevar_pop (TV_TREE_SSA_REWRITE_BLOCKS);
+ sbitmap_free (tmp);
/* Debugging dumps. */
- if (dump_file && (dump_flags & TDF_STATS))
+ if (dump_file)
{
- dump_dfa_stats (dump_file);
- dump_tree_ssa_stats (dump_file);
- }
+ int c;
+ unsigned i;
- /* Free allocated memory. */
- FOR_EACH_BB (bb)
- BITMAP_XFREE (dfs[bb->index]);
- free (dfs);
+ dump_update_ssa (dump_file);
- htab_delete (def_blocks);
+ fprintf (dump_file, "Incremental SSA update started at block: %d\n\n",
+ start_bb->index);
- for (i = 1; i < num_ssa_names; i++)
- {
- name = ssa_name (i);
- if (!SSA_NAME_AUX (name))
- continue;
+ c = 0;
+ EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi)
+ c++;
+ fprintf (dump_file, "Number of blocks in CFG: %d\n", last_basic_block);
+ fprintf (dump_file, "Number of blocks to update: %d (%3.0f%%)\n\n",
+ c, PERCENT (c, last_basic_block));
- free (SSA_NAME_AUX (name));
- SSA_NAME_AUX (name) = NULL;
- }
+ if (dump_flags & TDF_DETAILS)
+ {
+ fprintf (dump_file, "Affected blocks: ");
+ EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi)
+ fprintf (dump_file, "%u ", i);
+ fprintf (dump_file, "\n");
+ }
- BITMAP_XFREE (to_rename);
- timevar_pop (TV_TREE_SSA_OTHER);
-}
+ fprintf (dump_file, "\n\n");
+ }
-/* Rewrites all variables into ssa. */
+ /* Free allocated memory. */
+done:
+ delete_update_ssa ();
-static void
-rewrite_all_into_ssa (void)
-{
- rewrite_into_ssa (true);
+ timevar_pop (TV_TREE_SSA_INCREMENTAL);
}
-
-struct tree_opt_pass pass_build_ssa =
-{
- "ssa", /* name */
- NULL, /* gate */
- rewrite_all_into_ssa, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- 0, /* tv_id */
- PROP_cfg | PROP_referenced_vars, /* properties_required */
- PROP_ssa, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func | TODO_verify_ssa, /* todo_flags_finish */
- 0 /* letter */
-};
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