/* Alias analysis for trees.
- Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007 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, 51 Franklin Street, Fifth Floor,
-Boston, MA 02110-1301, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "bitmap.h"
#include "vecprim.h"
#include "pointer-set.h"
+#include "alloc-pool.h"
+
+/* Broad overview of how aliasing works:
+
+ First we compute points-to sets, which is done in
+ tree-ssa-structalias.c
+
+ During points-to set constraint finding, a bunch of little bits of
+ information is collected.
+ This is not done because it is necessary for points-to, but because
+ points-to has to walk every statement anyway. The function performing
+ this collecting is update_alias_info.
+
+ Bits update_alias_info collects include:
+ 1. Directly escaping variables and variables whose value escapes
+ (using is_escape_site). This is the set of variables and values that
+ escape prior to transitive closure of the clobbers.
+ 2. The set of variables dereferenced on the LHS (into
+ dereferenced_ptr_stores)
+ 3. The set of variables dereferenced on the RHS (into
+ dereferenced_ptr_loads)
+ 4. The set of all pointers we saw.
+ 5. The number of loads and stores for each variable
+ 6. The number of statements touching memory
+ 7. The set of address taken variables.
+
+
+ #1 is computed by a combination of is_escape_site, and counting the
+ number of uses/deref operators. This function properly accounts for
+ situations like &ptr->field, which is *not* a dereference.
+
+ After points-to sets are computed, the sets themselves still
+ contain points-to specific variables, such as a variable that says
+ the pointer points to anything, a variable that says the pointer
+ points to readonly memory, etc.
+
+ These are eliminated in a later phase, as we will see.
+
+ The rest of the phases are located in tree-ssa-alias.c
+
+ The next phase after points-to set computation is called
+ "setup_pointers_and_addressables"
+
+ This pass does 3 main things:
+
+ 1. All variables that can have TREE_ADDRESSABLE removed safely (IE
+ non-globals whose address is not taken), have TREE_ADDRESSABLE
+ removed.
+ 2. All variables that may be aliased (which is the set of addressable
+ variables and globals) at all, are marked for renaming, and have
+ symbol memory tags created for them.
+ 3. All variables which are stored into have their SMT's added to
+ written vars.
+
+
+ After this function is run, all variables that will ever have an
+ SMT, have one, though its aliases are not filled in.
+
+ The next phase is to compute flow-insensitive aliasing, which in
+ our case, is a misnomer. it is really computing aliasing that
+ requires no transitive closure to be correct. In particular, it
+ uses stack vs non-stack, TBAA, etc, to determine whether two
+ symbols could *ever* alias . This phase works by going through all
+ the pointers we collected during update_alias_info, and for every
+ addressable variable in the program, seeing if they alias. If so,
+ the addressable variable is added to the symbol memory tag for the
+ pointer.
+
+ As part of this, we handle symbol memory tags that conflict but
+ have no aliases in common, by forcing them to have a symbol in
+ common (through unioning alias sets or adding one as an alias of
+ the other), or by adding one as an alias of another. The case of
+ conflicts with no aliases in common occurs mainly due to aliasing
+ we cannot see. In particular, it generally means we have a load
+ through a pointer whose value came from outside the function.
+ Without an addressable symbol to point to, they would get the wrong
+ answer.
+
+ After flow insensitive aliasing is computed, we compute name tags
+ (called compute_flow_sensitive_info). We walk each pointer we
+ collected and see if it has a usable points-to set. If so, we
+ generate a name tag using that pointer, and make an alias bitmap for
+ it. Name tags are shared between all things with the same alias
+ bitmap. The alias bitmap will be translated from what points-to
+ computed. In particular, the "anything" variable in points-to will be
+ transformed into a pruned set of SMT's and their aliases that
+ compute_flow_insensitive_aliasing computed.
+ Note that since 4.3, every pointer that points-to computed a solution for
+ will get a name tag (whereas before 4.3, only those whose set did
+ *not* include the anything variable would). At the point where name
+ tags are all assigned, symbol memory tags are dead, and could be
+ deleted, *except* on global variables. Global variables still use
+ symbol memory tags as of right now.
+
+ After name tags are computed, the set of clobbered variables is
+ transitively closed. In particular, we compute the set of clobbered
+ variables based on the initial set of clobbers, plus the aliases of
+ pointers which either escape, or have their value escape.
+
+ After this, maybe_create_global_var is run, which handles a corner
+ case where we have no call clobbered variables, but have pure and
+ non-pure functions.
+
+ Staring at this function, I now remember it is a hack for the fact
+ that we do not mark all globals in the program as call clobbered for a
+ function unless they are actually used in that function. Instead, we
+ only mark the set that is actually clobbered. As a result, you can
+ end up with situations where you have no call clobbered vars set.
+
+ After maybe_create_global_var, we set pointers with the REF_ALL flag
+ to have alias sets that include all clobbered
+ memory tags and variables.
+
+ After this, memory partitioning is computed (by the function
+ compute_memory_partitions) and alias sets are reworked accordingly.
+
+ Lastly, we delete partitions with no symbols, and clean up after
+ ourselves. */
/* Structure to map a variable to its alias set. */
struct alias_map_d
{
/* Variable and its alias set. */
tree var;
- HOST_WIDE_INT set;
+ alias_set_type set;
};
-/* Data structures used for computing memory partitions. */
-
-struct mp_info_def
-{
- /* Symbol or memory tag. */
- tree var;
-
- /* Number of virtual operators needed to represent references to VAR. */
- long num_vops;
-};
-
-typedef struct mp_info_def *mp_info_t;
-DEF_VEC_P(mp_info_t);
-DEF_VEC_ALLOC_P(mp_info_t, heap);
-
/* Counters used to display statistics on alias analysis. */
struct alias_stats_d
{
static void compute_flow_insensitive_aliasing (struct alias_info *);
static void finalize_ref_all_pointers (struct alias_info *);
static void dump_alias_stats (FILE *);
-static bool may_alias_p (tree, HOST_WIDE_INT, tree, HOST_WIDE_INT, bool);
+static bool may_alias_p (tree, alias_set_type, tree, alias_set_type, bool);
static tree create_memory_tag (tree type, bool is_type_tag);
static tree get_smt_for (tree, struct alias_info *);
static tree get_nmt_for (tree);
static void compute_flow_sensitive_aliasing (struct alias_info *);
static void setup_pointers_and_addressables (struct alias_info *);
static void create_global_var (void);
-static void maybe_create_global_var (struct alias_info *ai);
-static void set_pt_anything (tree ptr);
+static void maybe_create_global_var (void);
+static void set_pt_anything (tree);
+
+void debug_mp_info (VEC(mem_sym_stats_t,heap) *);
+
+static alloc_pool mem_sym_stats_pool;
+
+/* Return memory reference stats for symbol VAR. Create a new slot in
+ cfun->gimple_df->mem_sym_stats if needed. */
+
+static struct mem_sym_stats_d *
+get_mem_sym_stats_for (tree var)
+{
+ void **slot;
+ struct mem_sym_stats_d *stats;
+ struct pointer_map_t *map = gimple_mem_ref_stats (cfun)->mem_sym_stats;
+
+ gcc_assert (map);
+
+ slot = pointer_map_insert (map, var);
+ if (*slot == NULL)
+ {
+ stats = pool_alloc (mem_sym_stats_pool);
+ memset (stats, 0, sizeof (*stats));
+ stats->var = var;
+ *slot = (void *) stats;
+ }
+ else
+ stats = (struct mem_sym_stats_d *) *slot;
+
+ return stats;
+}
+
+
+/* Return memory reference statistics for variable VAR in function FN.
+ This is computed by alias analysis, but it is not kept
+ incrementally up-to-date. So, these stats are only accurate if
+ pass_may_alias has been run recently. If no alias information
+ exists, this function returns NULL. */
-void dump_mp_info (FILE *, VEC(mp_info_t,heap) *mp_info_t);
-void debug_mp_info (VEC(mp_info_t,heap) *mp_info_t);
+static mem_sym_stats_t
+mem_sym_stats (struct function *fn, tree var)
+{
+ void **slot;
+ struct pointer_map_t *stats_map = gimple_mem_ref_stats (fn)->mem_sym_stats;
+
+ if (stats_map == NULL)
+ return NULL;
+
+ slot = pointer_map_contains (stats_map, var);
+ if (slot == NULL)
+ return NULL;
+
+ return (mem_sym_stats_t) *slot;
+}
+
+
+/* Set MPT to be the memory partition associated with symbol SYM. */
+
+static inline void
+set_memory_partition (tree sym, tree mpt)
+{
+#if defined ENABLE_CHECKING
+ if (mpt)
+ gcc_assert (TREE_CODE (mpt) == MEMORY_PARTITION_TAG
+ && !is_gimple_reg (sym));
+#endif
+
+ var_ann (sym)->mpt = mpt;
+ if (mpt)
+ {
+ if (MPT_SYMBOLS (mpt) == NULL)
+ MPT_SYMBOLS (mpt) = BITMAP_ALLOC (&alias_bitmap_obstack);
+
+ bitmap_set_bit (MPT_SYMBOLS (mpt), DECL_UID (sym));
+
+ /* MPT inherits the call-clobbering attributes from SYM. */
+ if (is_call_clobbered (sym))
+ {
+ MTAG_GLOBAL (mpt) = 1;
+ mark_call_clobbered (mpt, ESCAPE_IS_GLOBAL);
+ }
+ }
+}
-/* Global declarations. */
/* Mark variable VAR as being non-addressable. */
if (mpt)
{
- bitmap_clear_bit (MPT_SYMBOLS (mpt), DECL_UID (var));
+ /* Note that it's possible for a symbol to have an associated
+ MPT and the MPT have a NULL empty set. During
+ init_alias_info, all MPTs get their sets cleared out, but the
+ symbols still point to the old MPTs that used to hold them.
+ This is done so that compute_memory_partitions can now which
+ symbols are losing or changing partitions and mark them for
+ renaming. */
+ if (MPT_SYMBOLS (mpt))
+ bitmap_clear_bit (MPT_SYMBOLS (mpt), DECL_UID (var));
set_memory_partition (var, NULL_TREE);
}
}
static int
sort_tags_by_id (const void *pa, const void *pb)
{
- tree a = *(tree *)pa;
- tree b = *(tree *)pb;
+ const_tree const a = *(const_tree const *)pa;
+ const_tree const b = *(const_tree const *)pb;
return DECL_UID (a) - DECL_UID (b);
}
static void
init_transitive_clobber_worklist (VEC (tree, heap) **worklist,
- VEC (int, heap) **worklist2)
+ VEC (int, heap) **worklist2,
+ bitmap on_worklist)
{
referenced_var_iterator rvi;
tree curr;
if (MTAG_P (curr) && is_call_clobbered (curr))
{
VEC_safe_push (tree, heap, *worklist, curr);
- VEC_safe_push (int, heap, *worklist2, var_ann (curr)->escape_mask);
+ VEC_safe_push (int, heap, *worklist2,
+ var_ann (curr)->escape_mask);
+ bitmap_set_bit (on_worklist, DECL_UID (curr));
}
}
}
static void
add_to_worklist (tree alias, VEC (tree, heap) **worklist,
- VEC (int, heap) **worklist2,
- int reason)
+ VEC (int, heap) **worklist2, int reason,
+ bitmap on_worklist)
{
- if (MTAG_P (alias) && !is_call_clobbered (alias))
+ if (MTAG_P (alias) && !is_call_clobbered (alias)
+ && !bitmap_bit_p (on_worklist, DECL_UID (alias)))
{
VEC_safe_push (tree, heap, *worklist, alias);
VEC_safe_push (int, heap, *worklist2, reason);
+ bitmap_set_bit (on_worklist, DECL_UID (alias));
}
}
static void
mark_aliases_call_clobbered (tree tag, VEC (tree, heap) **worklist,
- VEC (int, heap) **worklist2)
+ VEC (int, heap) **worklist2,
+ bitmap on_worklist, bitmap queued)
{
bitmap aliases;
bitmap_iterator bi;
EXECUTE_IF_SET_IN_BITMAP (aliases, 0, i, bi)
{
entry = referenced_var (i);
- if (!unmodifiable_var_p (entry))
+ /* If you clobber one part of a structure, you
+ clobber the entire thing. While this does not make
+ the world a particularly nice place, it is necessary
+ in order to allow C/C++ tricks that involve
+ pointer arithmetic to work. */
+ if (TREE_CODE (entry) == STRUCT_FIELD_TAG)
+ bitmap_set_bit (queued, DECL_UID (SFT_PARENT_VAR (entry)));
+ else if (!unmodifiable_var_p (entry))
{
- add_to_worklist (entry, worklist, worklist2, ta->escape_mask);
+ add_to_worklist (entry, worklist, worklist2, ta->escape_mask,
+ on_worklist);
mark_call_clobbered (entry, ta->escape_mask);
}
}
+ if (!bitmap_empty_p (queued))
+ {
+ EXECUTE_IF_SET_IN_BITMAP (queued, 0, i, bi)
+ {
+ subvar_t svars = get_subvars_for_var (referenced_var (i));
+ unsigned int i;
+ tree subvar;
+
+ for (i = 0; VEC_iterate (tree, svars, i, subvar); ++i)
+ if (!unmodifiable_var_p (subvar))
+ mark_call_clobbered (subvar, ta->escape_mask);
+ }
+ bitmap_clear (queued);
+ }
}
/* Tags containing global vars need to be marked as global.
referenced_var_iterator rvi;
tree var;
tree ptr;
+ bitmap queued;
+
+ /* Temporary bitmap to avoid quadratic behavior in marking
+ call clobbers. */
+ queued = BITMAP_ALLOC (&alias_bitmap_obstack);
FOR_EACH_REFERENCED_VAR (var, rvi)
{
bitmap_iterator bi;
unsigned int j;
EXECUTE_IF_SET_IN_BITMAP (pi->pt_vars, 0, j, bi)
- if (!unmodifiable_var_p (referenced_var (j)))
- mark_call_clobbered (referenced_var (j), pi->escape_mask);
+ {
+ tree alias = referenced_var (j);
+
+ /* If you clobber one part of a structure, you
+ clobber the entire thing. While this does not make
+ the world a particularly nice place, it is necessary
+ in order to allow C/C++ tricks that involve
+ pointer arithmetic to work. */
+ if (TREE_CODE (alias) == STRUCT_FIELD_TAG)
+ bitmap_set_bit (queued, DECL_UID (SFT_PARENT_VAR (alias)));
+ else if (!unmodifiable_var_p (alias))
+ mark_call_clobbered (alias, pi->escape_mask);
+ }
+ /* Process variables we need to clobber all parts of. */
+ if (!bitmap_empty_p (queued))
+ {
+ EXECUTE_IF_SET_IN_BITMAP (queued, 0, j, bi)
+ {
+ subvar_t svars = get_subvars_for_var (referenced_var (j));
+ unsigned int i;
+ tree subvar;
+
+ for (i = 0; VEC_iterate (tree, svars, i, subvar); ++i)
+ if (!unmodifiable_var_p (subvar))
+ mark_call_clobbered (subvar, pi->escape_mask);
+ }
+ bitmap_clear (queued);
+ }
}
}
MTAG_GLOBAL (tag) = true;
}
}
+
+ BITMAP_FREE (queued);
}
/* Compute which variables need to be marked call clobbered because
compute_call_clobbered (struct alias_info *ai)
{
VEC (tree, heap) *worklist = NULL;
- VEC(int,heap) *worklist2 = NULL;
-
+ VEC (int,heap) *worklist2 = NULL;
+ bitmap on_worklist, queued;
+
+ timevar_push (TV_CALL_CLOBBER);
+ on_worklist = BITMAP_ALLOC (NULL);
+ queued = BITMAP_ALLOC (NULL);
+
set_initial_properties (ai);
- init_transitive_clobber_worklist (&worklist, &worklist2);
+ init_transitive_clobber_worklist (&worklist, &worklist2, on_worklist);
while (VEC_length (tree, worklist) != 0)
{
tree curr = VEC_pop (tree, worklist);
int reason = VEC_pop (int, worklist2);
-
+
+ bitmap_clear_bit (on_worklist, DECL_UID (curr));
mark_call_clobbered (curr, reason);
- mark_aliases_call_clobbered (curr, &worklist, &worklist2);
+ mark_aliases_call_clobbered (curr, &worklist, &worklist2,
+ on_worklist, queued);
}
VEC_free (tree, heap, worklist);
VEC_free (int, heap, worklist2);
+ BITMAP_FREE (on_worklist);
+ BITMAP_FREE (queued);
compute_tag_properties ();
+ timevar_pop (TV_CALL_CLOBBER);
}
-/* Dump the MP_INFO array to FILE. */
-void
-dump_mp_info (FILE *file, VEC(mp_info_t,heap) *mp_info)
+/* Dump memory partition information to FILE. */
+
+static void
+dump_memory_partitions (FILE *file)
{
- unsigned i;
- mp_info_t mp_p;
+ unsigned i, npart;
+ unsigned long nsyms;
+ tree mpt;
- for (i = 0; VEC_iterate (mp_info_t, mp_info, i, mp_p); i++)
+ fprintf (file, "\nMemory partitions\n\n");
+ for (i = 0, npart = 0, nsyms = 0;
+ VEC_iterate (tree, gimple_ssa_operands (cfun)->mpt_table, i, mpt);
+ i++)
{
- fprintf (file, "%6lu\t", mp_p->num_vops);
- if (mp_p->var == NULL_TREE)
+ if (mpt)
{
- fprintf (file, "CALL-CLOBBERED SYMBOLS: ");
- dump_decl_set (file, gimple_call_clobbered_vars (cfun));
+ bitmap syms = MPT_SYMBOLS (mpt);
+ unsigned long n = (syms) ? bitmap_count_bits (syms) : 0;
+
+ fprintf (file, "#%u: ", i);
+ print_generic_expr (file, mpt, 0);
+ fprintf (file, ": %lu elements: ", n);
+ dump_decl_set (file, syms);
+ npart++;
+ nsyms += n;
}
- else
- dump_variable (file, mp_p->var);
+ }
+
+ fprintf (file, "\n%u memory partitions holding %lu symbols\n", npart, nsyms);
+}
+
+
+/* Dump memory partition information to stderr. */
+
+void
+debug_memory_partitions (void)
+{
+ dump_memory_partitions (stderr);
+}
+
+
+/* Return true if memory partitioning is required given the memory
+ reference estimates in STATS. */
+
+static inline bool
+need_to_partition_p (struct mem_ref_stats_d *stats)
+{
+ long num_vops = stats->num_vuses + stats->num_vdefs;
+ long avg_vops = CEIL (num_vops, stats->num_mem_stmts);
+ return (num_vops > (long) MAX_ALIASED_VOPS
+ && avg_vops > (long) AVG_ALIASED_VOPS);
+}
+
+
+/* Count the actual number of virtual operators in CFUN. Note that
+ this is only meaningful after virtual operands have been populated,
+ so it should be invoked at the end of compute_may_aliases.
+
+ The number of virtual operators are stored in *NUM_VDEFS_P and
+ *NUM_VUSES_P, the number of partitioned symbols in
+ *NUM_PARTITIONED_P and the number of unpartitioned symbols in
+ *NUM_UNPARTITIONED_P.
+
+ If any of these pointers is NULL the corresponding count is not
+ computed. */
+
+static void
+count_mem_refs (long *num_vuses_p, long *num_vdefs_p,
+ long *num_partitioned_p, long *num_unpartitioned_p)
+{
+ block_stmt_iterator bsi;
+ basic_block bb;
+ long num_vdefs, num_vuses, num_partitioned, num_unpartitioned;
+ referenced_var_iterator rvi;
+ tree sym;
+
+ num_vuses = num_vdefs = num_partitioned = num_unpartitioned = 0;
+
+ if (num_vuses_p || num_vdefs_p)
+ FOR_EACH_BB (bb)
+ for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ {
+ tree stmt = bsi_stmt (bsi);
+ if (stmt_references_memory_p (stmt))
+ {
+ num_vuses += NUM_SSA_OPERANDS (stmt, SSA_OP_VUSE);
+ num_vdefs += NUM_SSA_OPERANDS (stmt, SSA_OP_VDEF);
+ }
+ }
+
+ if (num_partitioned_p || num_unpartitioned_p)
+ FOR_EACH_REFERENCED_VAR (sym, rvi)
+ {
+ if (is_gimple_reg (sym))
+ continue;
+
+ if (memory_partition (sym))
+ num_partitioned++;
+ else
+ num_unpartitioned++;
+ }
+
+ if (num_vdefs_p)
+ *num_vdefs_p = num_vdefs;
+
+ if (num_vuses_p)
+ *num_vuses_p = num_vuses;
+
+ if (num_partitioned_p)
+ *num_partitioned_p = num_partitioned;
+
+ if (num_unpartitioned_p)
+ *num_unpartitioned_p = num_unpartitioned;
+}
+
+
+/* The list is sorted by increasing partitioning score (PSCORE).
+ This score is computed such that symbols with high scores are
+ those that are least likely to be partitioned. Given a symbol
+ MP->VAR, PSCORE(S) is the result of the following weighted sum
+
+ PSCORE(S) = FW * 64 + FR * 32
+ + DW * 16 + DR * 8
+ + IW * 4 + IR * 2
+ + NO_ALIAS
+
+ where
+
+ FW Execution frequency of writes to S
+ FR Execution frequency of reads from S
+ DW Number of direct writes to S
+ DR Number of direct reads from S
+ IW Number of indirect writes to S
+ IR Number of indirect reads from S
+ NO_ALIAS State of the NO_ALIAS* flags
+
+ The basic idea here is that symbols that are frequently
+ written-to in hot paths of the code are the last to be considered
+ for partitioning. */
+
+static inline long
+mem_sym_score (mem_sym_stats_t mp)
+{
+ /* Unpartitionable SFTs are automatically thrown to the bottom of
+ the list. They are not stored in partitions, but they are used
+ for computing overall statistics. */
+ if (TREE_CODE (mp->var) == STRUCT_FIELD_TAG
+ && SFT_UNPARTITIONABLE_P (mp->var))
+ return LONG_MAX;
+
+ return mp->frequency_writes * 64 + mp->frequency_reads * 32
+ + mp->num_direct_writes * 16 + mp->num_direct_reads * 8
+ + mp->num_indirect_writes * 4 + mp->num_indirect_reads * 2
+ + var_ann (mp->var)->noalias_state;
+}
+
+
+/* Dump memory reference stats for function CFUN to FILE. */
+
+void
+dump_mem_ref_stats (FILE *file)
+{
+ long actual_num_vuses, actual_num_vdefs;
+ long num_partitioned, num_unpartitioned;
+ struct mem_ref_stats_d *stats;
+
+ stats = gimple_mem_ref_stats (cfun);
+
+ count_mem_refs (&actual_num_vuses, &actual_num_vdefs, &num_partitioned,
+ &num_unpartitioned);
+
+ fprintf (file, "\nMemory reference statistics for %s\n\n",
+ lang_hooks.decl_printable_name (current_function_decl, 2));
+
+ fprintf (file, "Number of memory statements: %ld\n",
+ stats->num_mem_stmts);
+ fprintf (file, "Number of call sites: %ld\n",
+ stats->num_call_sites);
+ fprintf (file, "Number of pure/const call sites: %ld\n",
+ stats->num_pure_const_call_sites);
+ fprintf (file, "Number of asm sites: %ld\n",
+ stats->num_asm_sites);
+ fprintf (file, "Estimated number of loads: %ld (%ld/stmt)\n",
+ stats->num_vuses,
+ (stats->num_mem_stmts)
+ ? CEIL (stats->num_vuses, stats->num_mem_stmts)
+ : 0);
+ fprintf (file, "Actual number of loads: %ld (%ld/stmt)\n",
+ actual_num_vuses,
+ (stats->num_mem_stmts)
+ ? CEIL (actual_num_vuses, stats->num_mem_stmts)
+ : 0);
+
+ if (actual_num_vuses > stats->num_vuses + (stats->num_vuses / 25))
+ fprintf (file, "\t(warning: estimation is lower by more than 25%%)\n");
+
+ fprintf (file, "Estimated number of stores: %ld (%ld/stmt)\n",
+ stats->num_vdefs,
+ (stats->num_mem_stmts)
+ ? CEIL (stats->num_vdefs, stats->num_mem_stmts)
+ : 0);
+ fprintf (file, "Actual number of stores: %ld (%ld/stmt)\n",
+ actual_num_vdefs,
+ (stats->num_mem_stmts)
+ ? CEIL (actual_num_vdefs, stats->num_mem_stmts)
+ : 0);
+
+ if (actual_num_vdefs > stats->num_vdefs + (stats->num_vdefs / 25))
+ fprintf (file, "\t(warning: estimation is lower by more than 25%%)\n");
+
+ fprintf (file, "Partitioning thresholds: MAX = %d AVG = %d "
+ "(%sNEED TO PARTITION)\n", MAX_ALIASED_VOPS, AVG_ALIASED_VOPS,
+ stats->num_mem_stmts && need_to_partition_p (stats) ? "" : "NO ");
+ fprintf (file, "Number of partitioned symbols: %ld\n", num_partitioned);
+ fprintf (file, "Number of unpartitioned symbols: %ld\n", num_unpartitioned);
+}
+
+
+/* Dump memory reference stats for function FN to stderr. */
+
+void
+debug_mem_ref_stats (void)
+{
+ dump_mem_ref_stats (stderr);
+}
+
+
+/* Dump memory reference stats for variable VAR to FILE. */
+
+static void
+dump_mem_sym_stats (FILE *file, tree var)
+{
+ mem_sym_stats_t stats = mem_sym_stats (cfun, var);
+
+ if (stats == NULL)
+ return;
+
+ fprintf (file, "read frequency: %6ld, write frequency: %6ld, "
+ "direct reads: %3ld, direct writes: %3ld, "
+ "indirect reads: %4ld, indirect writes: %4ld, symbol: ",
+ stats->frequency_reads, stats->frequency_writes,
+ stats->num_direct_reads, stats->num_direct_writes,
+ stats->num_indirect_reads, stats->num_indirect_writes);
+ print_generic_expr (file, stats->var, 0);
+ fprintf (file, ", tags: ");
+ dump_decl_set (file, stats->parent_tags);
+}
+
+
+/* Dump memory reference stats for variable VAR to stderr. */
+
+void
+debug_mem_sym_stats (tree var)
+{
+ dump_mem_sym_stats (stderr, var);
+}
+
+/* Dump memory reference stats for variable VAR to FILE. For use
+ of tree-dfa.c:dump_variable. */
+
+void
+dump_mem_sym_stats_for_var (FILE *file, tree var)
+{
+ mem_sym_stats_t stats = mem_sym_stats (cfun, var);
+
+ if (stats == NULL)
+ return;
+
+ fprintf (file, ", score: %ld", mem_sym_score (stats));
+ fprintf (file, ", direct reads: %ld", stats->num_direct_reads);
+ fprintf (file, ", direct writes: %ld", stats->num_direct_writes);
+ fprintf (file, ", indirect reads: %ld", stats->num_indirect_reads);
+ fprintf (file, ", indirect writes: %ld", stats->num_indirect_writes);
+}
+
+/* Dump memory reference stats for all memory symbols to FILE. */
+
+static void
+dump_all_mem_sym_stats (FILE *file)
+{
+ referenced_var_iterator rvi;
+ tree sym;
+
+ FOR_EACH_REFERENCED_VAR (sym, rvi)
+ {
+ if (is_gimple_reg (sym))
+ continue;
+
+ dump_mem_sym_stats (file, sym);
}
}
+/* Dump memory reference stats for all memory symbols to stderr. */
+
+void
+debug_all_mem_sym_stats (void)
+{
+ dump_all_mem_sym_stats (stderr);
+}
+
+
+/* Dump the MP_INFO array to FILE. */
+
+static void
+dump_mp_info (FILE *file, VEC(mem_sym_stats_t,heap) *mp_info)
+{
+ unsigned i;
+ mem_sym_stats_t mp_p;
+
+ for (i = 0; VEC_iterate (mem_sym_stats_t, mp_info, i, mp_p); i++)
+ if (!mp_p->partitioned_p)
+ dump_mem_sym_stats (file, mp_p->var);
+}
+
+
/* Dump the MP_INFO array to stderr. */
void
-debug_mp_info (VEC(mp_info_t,heap) *mp_info)
+debug_mp_info (VEC(mem_sym_stats_t,heap) *mp_info)
{
dump_mp_info (stderr, mp_info);
}
-/* Comparison function for qsort used in sort_mp_info. */
+/* Update memory reference stats for symbol VAR in statement STMT.
+ NUM_DIRECT_READS and NUM_DIRECT_WRITES specify the number of times
+ that VAR is read/written in STMT (indirect reads/writes are not
+ recorded by this function, see compute_memory_partitions). */
-static int
-mp_info_cmp (const void *p, const void *q)
+void
+update_mem_sym_stats_from_stmt (tree var, tree stmt, long num_direct_reads,
+ long num_direct_writes)
{
- mp_info_t e1 = *((const mp_info_t *) p);
- mp_info_t e2 = *((const mp_info_t *) q);
+ mem_sym_stats_t stats;
- /* We want to sort in decreasing order. */
- if (e1->num_vops < e2->num_vops)
- return 1;
- else if (e1->num_vops > e2->num_vops)
+ gcc_assert (num_direct_reads >= 0 && num_direct_writes >= 0);
+
+ stats = get_mem_sym_stats_for (var);
+
+ stats->num_direct_reads += num_direct_reads;
+ stats->frequency_reads += ((long) bb_for_stmt (stmt)->frequency
+ * num_direct_reads);
+
+ stats->num_direct_writes += num_direct_writes;
+ stats->frequency_writes += ((long) bb_for_stmt (stmt)->frequency
+ * num_direct_writes);
+}
+
+
+/* Given two MP_INFO entries MP1 and MP2, return -1 if MP1->VAR should
+ be partitioned before MP2->VAR, 0 if they are the same or 1 if
+ MP1->VAR should be partitioned after MP2->VAR. */
+
+static inline int
+compare_mp_info_entries (mem_sym_stats_t mp1, mem_sym_stats_t mp2)
+{
+ long pscore1 = mem_sym_score (mp1);
+ long pscore2 = mem_sym_score (mp2);
+
+ if (pscore1 < pscore2)
return -1;
+ else if (pscore1 > pscore2)
+ return 1;
else
- return 0;
+ return DECL_UID (mp1->var) - DECL_UID (mp2->var);
+}
+
+
+/* Comparison routine for qsort. The list is sorted by increasing
+ partitioning score (PSCORE). This score is computed such that
+ symbols with high scores are those that are least likely to be
+ partitioned. */
+
+static int
+mp_info_cmp (const void *p, const void *q)
+{
+ mem_sym_stats_t e1 = *((const mem_sym_stats_t *) p);
+ mem_sym_stats_t e2 = *((const mem_sym_stats_t *) q);
+ return compare_mp_info_entries (e1, e2);
}
/* Sort the array of reference counts used to compute memory partitions.
- Elements are sorted in descending order of virtual operators needed. */
+ Elements are sorted in ascending order of execution frequency and
+ descending order of virtual operators needed. */
static inline void
-sort_mp_info (VEC(mp_info_t,heap) *list)
+sort_mp_info (VEC(mem_sym_stats_t,heap) *list)
{
- unsigned num = VEC_length (mp_info_t, list);
+ unsigned num = VEC_length (mem_sym_stats_t, list);
if (num < 2)
return;
if (num == 2)
{
- if (VEC_index (mp_info_t, list, 0)->num_vops
- < VEC_index (mp_info_t, list, 1)->num_vops)
+ if (compare_mp_info_entries (VEC_index (mem_sym_stats_t, list, 0),
+ VEC_index (mem_sym_stats_t, list, 1)) > 0)
{
/* Swap elements if they are in the wrong order. */
- mp_info_t tmp = VEC_index (mp_info_t, list, 0);
- VEC_replace (mp_info_t, list, 0, VEC_index (mp_info_t, list, 1));
- VEC_replace (mp_info_t, list, 1, tmp);
+ mem_sym_stats_t tmp = VEC_index (mem_sym_stats_t, list, 0);
+ VEC_replace (mem_sym_stats_t, list, 0,
+ VEC_index (mem_sym_stats_t, list, 1));
+ VEC_replace (mem_sym_stats_t, list, 1, tmp);
}
return;
}
/* There are 3 or more elements, call qsort. */
- qsort (VEC_address (mp_info_t, list), VEC_length (mp_info_t, list),
- sizeof (mp_info_t), mp_info_cmp);
+ qsort (VEC_address (mem_sym_stats_t, list),
+ VEC_length (mem_sym_stats_t, list),
+ sizeof (mem_sym_stats_t),
+ mp_info_cmp);
}
-/* Create a new partition to hold all the symbols aliased with
- MP_P->VAR. If MP_P->VAR is NULL, it partitions the call-clobbered
- variables. Only symbols that are not already in another partition
- are added to the new partition created for MP_P->VAR. */
+/* Return the memory partition tag (MPT) associated with memory
+ symbol SYM. */
-static void
-create_partition_for (mp_info_t mp_p)
+static tree
+get_mpt_for (tree sym)
{
- bitmap_iterator bi;
- tree mpt, sym;
- bitmap aliases;
- unsigned i;
-
- if (mp_p->num_vops <= (long) MAX_ALIASED_VOPS)
- return;
+ tree mpt;
- if (mp_p->var == NULL_TREE)
+ /* Don't create a new tag unnecessarily. */
+ mpt = memory_partition (sym);
+ if (mpt == NULL_TREE)
{
- bitmap_iterator bi;
- bitmap tmp;
+ mpt = create_tag_raw (MEMORY_PARTITION_TAG, TREE_TYPE (sym), "MPT");
+ TREE_ADDRESSABLE (mpt) = 0;
+ add_referenced_var (mpt);
+ VEC_safe_push (tree, heap, gimple_ssa_operands (cfun)->mpt_table, mpt);
+ gcc_assert (MPT_SYMBOLS (mpt) == NULL);
+ set_memory_partition (sym, mpt);
+ }
- /* Since the partitions we create for call-clobbered variables
- will also be marked call-clobbered, make a copy of the
- original set to avoid confusing the iterator. */
- tmp = BITMAP_ALLOC (NULL);
- bitmap_copy (tmp, gimple_call_clobbered_vars (cfun));
+ return mpt;
+}
- /* Process call-clobbered symbols when no MP_P->VAR is given. */
- mpt = NULL_TREE;
- EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi)
- {
- tree sym = referenced_var (i);
- if (memory_partition (sym) == NULL_TREE)
- {
- if (mpt == NULL_TREE)
- {
- mpt = get_mpt_for (sym);
- mp_p->num_vops++;
- }
- mark_sym_for_renaming (mpt);
- mark_sym_for_renaming (sym);
- set_memory_partition (sym, mpt);
- }
+/* Add MP_P->VAR to a memory partition and return the partition. */
- mp_p->num_vops--;
+static tree
+find_partition_for (mem_sym_stats_t mp_p)
+{
+ unsigned i;
+ VEC(tree,heap) *mpt_table;
+ tree mpt;
- /* If we have already grouped enough, stop. */
- if (mp_p->num_vops <= (long) MAX_ALIASED_VOPS)
- break;
- }
+ mpt_table = gimple_ssa_operands (cfun)->mpt_table;
+ mpt = NULL_TREE;
- BITMAP_FREE (tmp);
- }
- else
+ /* Find an existing partition for MP_P->VAR. */
+ for (i = 0; VEC_iterate (tree, mpt_table, i, mpt); i++)
{
- aliases = may_aliases (mp_p->var);
- gcc_assert (!bitmap_empty_p (aliases));
+ mem_sym_stats_t mpt_stats;
- mpt = NULL_TREE;
- EXECUTE_IF_SET_IN_BITMAP (aliases, 0, i, bi)
- {
- sym = referenced_var (i);
- /* Only set the memory partition for aliased symbol SYM if
- SYM does not belong to another partition. */
- if (memory_partition (sym) == NULL_TREE)
- {
- if (mpt == NULL_TREE)
- {
- mpt = get_mpt_for (mp_p->var);
- mp_p->num_vops++;
- }
+ /* If MPT does not have any symbols yet, use it. */
+ if (MPT_SYMBOLS (mpt) == NULL)
+ break;
- mark_sym_for_renaming (mpt);
- mark_sym_for_renaming (sym);
- set_memory_partition (sym, mpt);
- }
+ /* Otherwise, see if MPT has common parent tags with MP_P->VAR,
+ but avoid grouping clobbered variables with non-clobbered
+ variables (otherwise, this tends to creates a single memory
+ partition because other call-clobbered variables may have
+ common parent tags with non-clobbered ones). */
+ mpt_stats = get_mem_sym_stats_for (mpt);
+ if (mp_p->parent_tags
+ && mpt_stats->parent_tags
+ && is_call_clobbered (mpt) == is_call_clobbered (mp_p->var)
+ && bitmap_intersect_p (mpt_stats->parent_tags, mp_p->parent_tags))
+ break;
+
+ /* If no common parent tags are found, see if both MPT and
+ MP_P->VAR are call-clobbered. */
+ if (is_call_clobbered (mpt) && is_call_clobbered (mp_p->var))
+ break;
+ }
- mp_p->num_vops--;
+ if (mpt == NULL_TREE)
+ mpt = get_mpt_for (mp_p->var);
+ else
+ set_memory_partition (mp_p->var, mpt);
- /* If we have already grouped enough, stop. */
- if (mp_p->num_vops <= (long) MAX_ALIASED_VOPS)
- break;
- }
+ mp_p->partitioned_p = true;
- if (mpt)
- mark_call_clobbered (mpt, ESCAPE_UNKNOWN);
- }
+ mark_sym_for_renaming (mp_p->var);
+ mark_sym_for_renaming (mpt);
+
+ return mpt;
}
unsigned i;
tree mpt, sym;
- if (tag == NULL_TREE)
+ EXECUTE_IF_SET_IN_BITMAP (MTAG_ALIASES (tag), 0, i, bi)
{
- /* Do not rewrite CALL_CLOBBERED_VARS. If a symbol S is taken
- out of this set, the optimizers will no longer consider S as
- call-clobbered, and that may lead to wrong transformations
- (e.g., pass_tail_calls explicitly examines all the symbols in
- the function to determine if it should enable tail-call
- marking). */
- return;
+ sym = referenced_var (i);
+ mpt = memory_partition (sym);
+ if (mpt)
+ bitmap_set_bit (new_aliases, DECL_UID (mpt));
+ else
+ bitmap_set_bit (new_aliases, DECL_UID (sym));
}
- else
+
+ /* Rebuild the may-alias array for TAG. */
+ bitmap_copy (MTAG_ALIASES (tag), new_aliases);
+}
+
+
+/* Determine how many virtual operands can be saved by partitioning
+ MP_P->VAR into MPT. When a symbol S is thrown inside a partition
+ P, every virtual operand that used to reference S will now
+ reference P. Whether it reduces the number of virtual operands
+ depends on:
+
+ 1- Direct references to S are never saved. Instead of the virtual
+ operand to S, we will now have a virtual operand to P.
+
+ 2- Indirect references to S are reduced only for those memory tags
+ holding S that already had other symbols partitioned into P.
+ For instance, if a memory tag T has the alias set { a b S c },
+ the first time we partition S into P, the alias set will become
+ { a b P c }, so no virtual operands will be saved. However, if
+ we now partition symbol 'c' into P, then the alias set for T
+ will become { a b P }, so we will be saving one virtual operand
+ for every indirect reference to 'c'.
+
+ 3- Is S is call-clobbered, we save as many virtual operands as
+ call/asm sites exist in the code, but only if other
+ call-clobbered symbols have been grouped into P. The first
+ call-clobbered symbol that we group does not produce any
+ savings.
+
+ MEM_REF_STATS points to CFUN's memory reference information. */
+
+static void
+estimate_vop_reduction (struct mem_ref_stats_d *mem_ref_stats,
+ mem_sym_stats_t mp_p, tree mpt)
+{
+ unsigned i;
+ bitmap_iterator bi;
+ mem_sym_stats_t mpt_stats;
+
+ /* We should only get symbols with indirect references here. */
+ gcc_assert (mp_p->num_indirect_reads > 0 || mp_p->num_indirect_writes > 0);
+
+ /* Note that the only statistics we keep for MPT is the set of
+ parent tags to know which memory tags have had alias members
+ partitioned, and the indicator has_call_clobbered_vars.
+ Reference counts are not important for MPT. */
+ mpt_stats = get_mem_sym_stats_for (mpt);
+
+ /* Traverse all the parent tags for MP_P->VAR. For every tag T, if
+ partition P is already grouping aliases of T, then reduce the
+ number of virtual operands by the number of direct references
+ to T. */
+ if (mp_p->parent_tags)
+ {
+ if (mpt_stats->parent_tags == NULL)
+ mpt_stats->parent_tags = BITMAP_ALLOC (&alias_bitmap_obstack);
+
+ EXECUTE_IF_SET_IN_BITMAP (mp_p->parent_tags, 0, i, bi)
+ {
+ if (bitmap_bit_p (mpt_stats->parent_tags, i))
+ {
+ /* Partition MPT is already partitioning symbols in the
+ alias set for TAG. This means that we are now saving
+ 1 virtual operand for every direct reference to TAG. */
+ tree tag = referenced_var (i);
+ mem_sym_stats_t tag_stats = mem_sym_stats (cfun, tag);
+ mem_ref_stats->num_vuses -= tag_stats->num_direct_reads;
+ mem_ref_stats->num_vdefs -= tag_stats->num_direct_writes;
+ }
+ else
+ {
+ /* This is the first symbol in tag I's alias set that is
+ being grouped under MPT. We will not save any
+ virtual operands this time, but record that MPT is
+ grouping a symbol from TAG's alias set so that the
+ next time we get the savings. */
+ bitmap_set_bit (mpt_stats->parent_tags, i);
+ }
+ }
+ }
+
+ /* If MP_P->VAR is call-clobbered, and MPT is already grouping
+ call-clobbered symbols, then we will save as many virtual
+ operands as asm/call sites there are. */
+ if (is_call_clobbered (mp_p->var))
+ {
+ if (mpt_stats->has_call_clobbered_vars)
+ mem_ref_stats->num_vdefs -= mem_ref_stats->num_call_sites
+ + mem_ref_stats->num_asm_sites;
+ else
+ mpt_stats->has_call_clobbered_vars = true;
+ }
+}
+
+
+/* Helper for compute_memory_partitions. Transfer reference counts
+ from pointers to their pointed-to sets. Counters for pointers were
+ computed by update_alias_info. MEM_REF_STATS points to CFUN's
+ memory reference information. */
+
+static void
+update_reference_counts (struct mem_ref_stats_d *mem_ref_stats)
+{
+ unsigned i;
+ bitmap_iterator bi;
+ mem_sym_stats_t sym_stats;
+
+ for (i = 1; i < num_ssa_names; i++)
+ {
+ tree ptr;
+ struct ptr_info_def *pi;
+
+ ptr = ssa_name (i);
+ if (ptr
+ && POINTER_TYPE_P (TREE_TYPE (ptr))
+ && (pi = SSA_NAME_PTR_INFO (ptr)) != NULL
+ && pi->is_dereferenced)
+ {
+ unsigned j;
+ bitmap_iterator bj;
+ tree tag;
+ mem_sym_stats_t ptr_stats, tag_stats;
+
+ /* If PTR has flow-sensitive points-to information, use
+ PTR's name tag, otherwise use the symbol tag associated
+ with PTR's symbol. */
+ if (pi->name_mem_tag)
+ tag = pi->name_mem_tag;
+ else
+ tag = symbol_mem_tag (SSA_NAME_VAR (ptr));
+
+ ptr_stats = get_mem_sym_stats_for (ptr);
+ tag_stats = get_mem_sym_stats_for (tag);
+
+ /* TAG has as many direct references as dereferences we
+ found for its parent pointer. */
+ tag_stats->num_direct_reads += ptr_stats->num_direct_reads;
+ tag_stats->num_direct_writes += ptr_stats->num_direct_writes;
+
+ /* All the dereferences of pointer PTR are considered direct
+ references to PTR's memory tag (TAG). In turn,
+ references to TAG will become virtual operands for every
+ symbol in TAG's alias set. So, for every symbol ALIAS in
+ TAG's alias set, add as many indirect references to ALIAS
+ as direct references there are for TAG. */
+ if (MTAG_ALIASES (tag))
+ EXECUTE_IF_SET_IN_BITMAP (MTAG_ALIASES (tag), 0, j, bj)
+ {
+ tree alias = referenced_var (j);
+ sym_stats = get_mem_sym_stats_for (alias);
+
+ /* All the direct references to TAG are indirect references
+ to ALIAS. */
+ sym_stats->num_indirect_reads += ptr_stats->num_direct_reads;
+ sym_stats->num_indirect_writes += ptr_stats->num_direct_writes;
+ sym_stats->frequency_reads += ptr_stats->frequency_reads;
+ sym_stats->frequency_writes += ptr_stats->frequency_writes;
+
+ /* Indicate that TAG is one of ALIAS's parent tags. */
+ if (sym_stats->parent_tags == NULL)
+ sym_stats->parent_tags = BITMAP_ALLOC (&alias_bitmap_obstack);
+ bitmap_set_bit (sym_stats->parent_tags, DECL_UID (tag));
+ }
+ }
+ }
+
+ /* Call-clobbered symbols are indirectly written at every
+ call/asm site. */
+ EXECUTE_IF_SET_IN_BITMAP (gimple_call_clobbered_vars (cfun), 0, i, bi)
+ {
+ tree sym = referenced_var (i);
+ sym_stats = get_mem_sym_stats_for (sym);
+ sym_stats->num_indirect_writes += mem_ref_stats->num_call_sites
+ + mem_ref_stats->num_asm_sites;
+ }
+
+ /* Addressable symbols are indirectly written at some ASM sites.
+ Since only ASM sites that clobber memory actually affect
+ addressable symbols, this is an over-estimation. */
+ EXECUTE_IF_SET_IN_BITMAP (gimple_addressable_vars (cfun), 0, i, bi)
+ {
+ tree sym = referenced_var (i);
+ sym_stats = get_mem_sym_stats_for (sym);
+ sym_stats->num_indirect_writes += mem_ref_stats->num_asm_sites;
+ }
+}
+
+
+/* Helper for compute_memory_partitions. Add all memory symbols to
+ *MP_INFO_P and compute the initial estimate for the total number of
+ virtual operands needed. MEM_REF_STATS points to CFUN's memory
+ reference information. On exit, *TAGS_P will contain the list of
+ memory tags whose alias set need to be rewritten after
+ partitioning. */
+
+static void
+build_mp_info (struct mem_ref_stats_d *mem_ref_stats,
+ VEC(mem_sym_stats_t,heap) **mp_info_p,
+ VEC(tree,heap) **tags_p)
+{
+ tree var;
+ referenced_var_iterator rvi;
+
+ FOR_EACH_REFERENCED_VAR (var, rvi)
{
- /* Create a new alias set for TAG with the new partitions. */
+ mem_sym_stats_t sym_stats;
+ tree old_mpt;
- EXECUTE_IF_SET_IN_BITMAP (MTAG_ALIASES (tag), 0, i, bi)
+ /* We are only interested in memory symbols other than MPTs. */
+ if (is_gimple_reg (var) || TREE_CODE (var) == MEMORY_PARTITION_TAG)
+ continue;
+
+ /* Collect memory tags into the TAGS array so that we can
+ rewrite their alias sets after partitioning. */
+ if (MTAG_P (var) && MTAG_ALIASES (var))
+ VEC_safe_push (tree, heap, *tags_p, var);
+
+ /* Since we are going to re-compute partitions, any symbols that
+ used to belong to a partition must be detached from it and
+ marked for renaming. */
+ if ((old_mpt = memory_partition (var)) != NULL)
{
- sym = referenced_var (i);
- mpt = memory_partition (sym);
- if (mpt)
- bitmap_set_bit (new_aliases, DECL_UID (mpt));
- else
- bitmap_set_bit (new_aliases, DECL_UID (sym));
+ mark_sym_for_renaming (old_mpt);
+ set_memory_partition (var, NULL_TREE);
+ mark_sym_for_renaming (var);
+ }
+
+ sym_stats = get_mem_sym_stats_for (var);
+
+ /* Add VAR's reference info to MP_INFO. Note that the only
+ symbols that make sense to partition are those that have
+ indirect references. If a symbol S is always directly
+ referenced, partitioning it will not reduce the number of
+ virtual operators. The only symbols that are profitable to
+ partition are those that belong to alias sets and/or are
+ call-clobbered. */
+ if (sym_stats->num_indirect_reads > 0
+ || sym_stats->num_indirect_writes > 0)
+ VEC_safe_push (mem_sym_stats_t, heap, *mp_info_p, sym_stats);
+
+ /* Update the number of estimated VOPS. Note that direct
+ references to memory tags are always counted as indirect
+ references to their alias set members, so if a memory tag has
+ aliases, do not count its direct references to avoid double
+ accounting. */
+ if (!MTAG_P (var) || !MTAG_ALIASES (var))
+ {
+ mem_ref_stats->num_vuses += sym_stats->num_direct_reads;
+ mem_ref_stats->num_vdefs += sym_stats->num_direct_writes;
}
- /* Rebuild the may-alias array for TAG. */
- bitmap_copy (MTAG_ALIASES (tag), new_aliases);
+ mem_ref_stats->num_vuses += sym_stats->num_indirect_reads;
+ mem_ref_stats->num_vdefs += sym_stats->num_indirect_writes;
}
}
-/* Compute memory partitions.
-
- The partitioning is straightforward:
+/* Compute memory partitions. A memory partition (MPT) is an
+ arbitrary grouping of memory symbols, such that references to one
+ member of the group is considered a reference to all the members of
+ the group.
- 1- All the memory tags and call-clobbered that cause virtual
- operators are collected into the MP_INFO table together with the
- number of virtual operands that would be needed to represent all
- the members in the alias set.
-
- 2- MP_INFO is sorted in decreasing order of virtual operators.
-
- 3- For every memory tag T in MP_INFO, a new partition MP is created.
-
- 4- All the symbols S in T's alias set are examined. If S is not
- already in another partition then S is added to partition MP.
-
- 6- The estimate of VOPS is updated, if it falls below
- MAX_ALIASED_VOPS, we stop. */
+ As opposed to alias sets in memory tags, the grouping into
+ partitions is completely arbitrary and only done to reduce the
+ number of virtual operands. The only rule that needs to be
+ observed when creating memory partitions is that given two memory
+ partitions MPT.i and MPT.j, they must not contain symbols in
+ common.
+
+ Memory partitions are used when putting the program into Memory-SSA
+ form. In particular, in Memory-SSA PHI nodes are not computed for
+ individual memory symbols. They are computed for memory
+ partitions. This reduces the amount of PHI nodes in the SSA graph
+ at the expense of precision (i.e., it makes unrelated stores affect
+ each other).
+
+ However, it is possible to increase precision by changing this
+ partitioning scheme. For instance, if the partitioning scheme is
+ such that get_mpt_for is the identity function (that is,
+ get_mpt_for (s) = s), this will result in ultimate precision at the
+ expense of huge SSA webs.
+
+ At the other extreme, a partitioning scheme that groups all the
+ symbols in the same set results in minimal SSA webs and almost
+ total loss of precision.
+
+ There partitioning heuristic uses three parameters to decide the
+ order in which symbols are processed. The list of symbols is
+ sorted so that symbols that are more likely to be partitioned are
+ near the top of the list:
+
+ - Execution frequency. If a memory references is in a frequently
+ executed code path, grouping it into a partition may block useful
+ transformations and cause sub-optimal code generation. So, the
+ partition heuristic tries to avoid grouping symbols with high
+ execution frequency scores. Execution frequency is taken
+ directly from the basic blocks where every reference is made (see
+ update_mem_sym_stats_from_stmt), which in turn uses the
+ profile guided machinery, so if the program is compiled with PGO
+ enabled, more accurate partitioning decisions will be made.
+
+ - Number of references. Symbols with few references in the code,
+ are partitioned before symbols with many references.
+
+ - NO_ALIAS attributes. Symbols with any of the NO_ALIAS*
+ attributes are partitioned after symbols marked MAY_ALIAS.
+
+ Once the list is sorted, the partitioning proceeds as follows:
+
+ 1- For every symbol S in MP_INFO, create a new memory partition MP,
+ if necessary. To avoid memory partitions that contain symbols
+ from non-conflicting alias sets, memory partitions are
+ associated to the memory tag that holds S in its alias set. So,
+ when looking for a memory partition for S, the memory partition
+ associated with one of the memory tags holding S is chosen. If
+ none exists, a new one is created.
+
+ 2- Add S to memory partition MP.
+
+ 3- Reduce by 1 the number of VOPS for every memory tag holding S.
+
+ 4- If the total number of VOPS is less than MAX_ALIASED_VOPS or the
+ average number of VOPS per statement is less than
+ AVG_ALIASED_VOPS, stop. Otherwise, go to the next symbol in the
+ list. */
static void
compute_memory_partitions (void)
{
- referenced_var_iterator rvi;
- tree var;
+ tree tag;
unsigned i;
- struct mp_info_def mp;
- mp_info_t mp_p;
- VEC(mp_info_t,heap) *mp_info;
- long max_num_vops = 0;
+ mem_sym_stats_t mp_p;
+ VEC(mem_sym_stats_t,heap) *mp_info;
bitmap new_aliases;
+ VEC(tree,heap) *tags;
+ struct mem_ref_stats_d *mem_ref_stats;
+ int prev_max_aliased_vops;
- timevar_push (TV_MEMORY_PARTITIONING);
-
- mp_info = NULL;
- max_num_vops = 0;
+ mem_ref_stats = gimple_mem_ref_stats (cfun);
+ gcc_assert (mem_ref_stats->num_vuses == 0 && mem_ref_stats->num_vdefs == 0);
- /* Add reference counts for all the call-clobbered variables. */
- if (!bitmap_empty_p (gimple_call_clobbered_vars (cfun)))
- {
- mp.var = NULL_TREE;
- mp.num_vops = bitmap_count_bits (gimple_call_clobbered_vars (cfun));
- max_num_vops = mp.num_vops;
- mp_p = xcalloc (1, sizeof (*mp_p));
- *mp_p = mp;
- VEC_safe_push (mp_info_t, heap, mp_info, mp_p);
- }
+ if (mem_ref_stats->num_mem_stmts == 0)
+ return;
- /* Add reference counts for all the symbol tags. */
- FOR_EACH_REFERENCED_VAR (var, rvi)
- {
- if (TREE_CODE (var) != SYMBOL_MEMORY_TAG
- && TREE_CODE (var) != NAME_MEMORY_TAG)
- continue;
+ timevar_push (TV_MEMORY_PARTITIONING);
- /* Each reference to VAR will produce as many VOPs as elements
- exist in its alias set. */
- mp.var = var;
- if (!may_aliases (var))
- mp.num_vops = 0;
- else
- mp.num_vops = bitmap_count_bits (may_aliases (var));
+ mp_info = NULL;
+ tags = NULL;
+ prev_max_aliased_vops = MAX_ALIASED_VOPS;
- /* No point grouping singleton alias sets. */
- if (mp.num_vops <= 1)
- continue;
+ /* Since we clearly cannot lower the number of virtual operators
+ below the total number of memory statements in the function, we
+ may need to adjust MAX_ALIASED_VOPS beforehand. */
+ if (MAX_ALIASED_VOPS < mem_ref_stats->num_mem_stmts)
+ MAX_ALIASED_VOPS = mem_ref_stats->num_mem_stmts;
- mp_p = xcalloc (1, sizeof (*mp_p));
- *mp_p = mp;
- VEC_safe_push (mp_info_t, heap, mp_info, mp_p);
+ /* Update reference stats for all the pointed-to variables and
+ memory tags. */
+ update_reference_counts (mem_ref_stats);
- if (mp.num_vops > max_num_vops)
- max_num_vops = mp.num_vops;
- }
+ /* Add all the memory symbols to MP_INFO. */
+ build_mp_info (mem_ref_stats, &mp_info, &tags);
- if (dump_file)
+ /* No partitions required if we are below the threshold. */
+ if (!need_to_partition_p (mem_ref_stats))
{
- fprintf (dump_file, "\n%s: Maximum number of VOPS needed per statement: "
- "%ld\n", get_name (current_function_decl), max_num_vops);
+ if (dump_file)
+ fprintf (dump_file, "\nMemory partitioning NOT NEEDED for %s\n",
+ get_name (current_function_decl));
+ goto done;
}
- /* No partitions required if we are below the threshold. */
- if (max_num_vops <= (long) MAX_ALIASED_VOPS)
- goto done;
-
- /* Sort the MP_INFO array in order of decreasing number of
- virtual operands. */
+ /* Sort the MP_INFO array so that symbols that should be partitioned
+ first are near the top of the list. */
sort_mp_info (mp_info);
if (dump_file)
{
- fprintf (dump_file, "\nVOPS generated by pointer dereferences "
- "before partitioning:\n");
+ fprintf (dump_file, "\nMemory partitioning NEEDED for %s\n\n",
+ get_name (current_function_decl));
+ fprintf (dump_file, "Memory symbol references before partitioning:\n");
dump_mp_info (dump_file, mp_info);
}
- /* Now that we have all the VOP generating tags in the MP_INFO array
- sorted by decreasing number of VOPS, create memory partitions and
- group aliased symbols into those partitions. */
- for (i = 0; VEC_iterate (mp_info_t, mp_info, i, mp_p); i++)
+ /* Create partitions for variables in MP_INFO until we have enough
+ to lower the total number of VOPS below MAX_ALIASED_VOPS or if
+ the average number of VOPS per statement is below
+ AVG_ALIASED_VOPS. */
+ for (i = 0; VEC_iterate (mem_sym_stats_t, mp_info, i, mp_p); i++)
{
- /* Stop processing if we are already below the threshold. */
- if (mp_p->num_vops <= (long) MAX_ALIASED_VOPS)
+ tree mpt;
+
+ /* If we are below the threshold, stop. */
+ if (!need_to_partition_p (mem_ref_stats))
break;
- create_partition_for (mp_p);
+ /* SFTs that are marked unpartitionable should not be added to
+ partitions. These SFTs are special because they mark the
+ first SFT into a structure where a pointer is pointing to.
+ This is needed by the operand scanner to find adjacent
+ fields. See add_vars_for_offset for details. */
+ if (TREE_CODE (mp_p->var) == STRUCT_FIELD_TAG
+ && SFT_UNPARTITIONABLE_P (mp_p->var))
+ continue;
+
+ mpt = find_partition_for (mp_p);
+ estimate_vop_reduction (mem_ref_stats, mp_p, mpt);
}
/* After partitions have been created, rewrite alias sets to use
them instead of the original symbols. This way, if the alias set
was computed as { a b c d e f }, and the subset { b e f } was
grouped into partition MPT.3, then the new alias set for the tag
- will be { a c d MPT.3 }. */
- new_aliases = BITMAP_ALLOC (NULL);
-
- for (i = 0; VEC_iterate (mp_info_t, mp_info, i, mp_p); i++)
+ will be { a c d MPT.3 }.
+
+ Note that this is not strictly necessary. The operand scanner
+ will always check if a symbol belongs to a partition when adding
+ virtual operands. However, by reducing the size of the alias
+ sets to be scanned, the work needed inside the operand scanner is
+ significantly reduced. */
+ new_aliases = BITMAP_ALLOC (&alias_bitmap_obstack);
+
+ for (i = 0; VEC_iterate (tree, tags, i, tag); i++)
{
- rewrite_alias_set_for (mp_p->var, new_aliases);
+ rewrite_alias_set_for (tag, new_aliases);
bitmap_clear (new_aliases);
}
if (dump_file)
{
- fprintf (dump_file, "\nVOPS generated by pointer dereferences "
- "after partitioning:\n");
+ fprintf (dump_file, "\nMemory symbol references after partitioning:\n");
dump_mp_info (dump_file, mp_info);
}
done:
/* Free allocated memory. */
- for (i = 0; VEC_iterate (mp_info_t, mp_info, i, mp_p); i++)
- free (mp_p);
- VEC_free (mp_info_t, heap, mp_info);
-
- timevar_pop (TV_MEMORY_PARTITIONING);
-}
+ VEC_free (mem_sym_stats_t, heap, mp_info);
+ VEC_free (tree, heap, tags);
-/* This function computes the value of the is_aliased bit for
- variables. is_aliased is true for any variable that is in an
- alias bitmap. */
+ MAX_ALIASED_VOPS = prev_max_aliased_vops;
-static void
-compute_is_aliased (void)
-{
- referenced_var_iterator rvi;
- tree tag;
- bitmap aliased_vars = BITMAP_ALLOC (NULL);
- bitmap_iterator bi;
- unsigned int i;
-
- /* Add is_aliased for all vars pointed to by the symbol tags. */
- FOR_EACH_REFERENCED_VAR (tag, rvi)
- {
- bitmap aliases;
- if (TREE_CODE (tag) != SYMBOL_MEMORY_TAG
- && TREE_CODE (tag) != NAME_MEMORY_TAG)
- continue;
- aliases = MTAG_ALIASES (tag);
- if (!aliases)
- continue;
-
- bitmap_ior_into (aliased_vars, aliases);
- }
-
- EXECUTE_IF_SET_IN_BITMAP (aliased_vars, 0, i, bi)
- {
- tree var = referenced_var (i);
-
- var_ann (var)->is_aliased = true;
- }
-
- BITMAP_FREE (aliased_vars);
+ timevar_pop (TV_MEMORY_PARTITIONING);
}
compilation time.
When the number of virtual operands needed to represent aliased
- loads and stores grows too large (configurable with @option{--param
- max-aliased-vops}), alias sets are grouped to avoid severe
- compile-time slow downs and memory consumption. See group_aliases. */
+ loads and stores grows too large (configurable with option --param
+ max-aliased-vops and --param avg-aliased-vops), alias sets are
+ grouped to avoid severe compile-time slow downs and memory
+ consumption. See compute_memory_partitions. */
-static unsigned int
+unsigned int
compute_may_aliases (void)
{
struct alias_info *ai;
+
+ timevar_push (TV_TREE_MAY_ALIAS);
memset (&alias_stats, 0, sizeof (alias_stats));
contains a mixture of pure and non-pure functions, then we need
to create use-def and def-def links between these functions to
avoid invalid transformations on them. */
- maybe_create_global_var (ai);
+ maybe_create_global_var ();
/* If the program contains ref-all pointers, finalize may-alias information
for them. This pass needs to be run after call-clobbering information
/* Compute memory partitions for every memory variable. */
compute_memory_partitions ();
+ /* Remove partitions with no symbols. Partitions may end up with an
+ empty MPT_SYMBOLS set if a previous round of alias analysis
+ needed to partition more symbols. Since we don't need those
+ partitions anymore, remove them to free up the space. */
+ {
+ tree mpt;
+ unsigned i;
+ VEC(tree,heap) *mpt_table;
+
+ mpt_table = gimple_ssa_operands (cfun)->mpt_table;
+ i = 0;
+ while (i < VEC_length (tree, mpt_table))
+ {
+ mpt = VEC_index (tree, mpt_table, i);
+ if (MPT_SYMBOLS (mpt) == NULL)
+ VEC_unordered_remove (tree, mpt_table, i);
+ else
+ i++;
+ }
+ }
+
+ /* Populate all virtual operands and newly promoted register operands. */
+ {
+ block_stmt_iterator bsi;
+ basic_block bb;
+ FOR_EACH_BB (bb)
+ for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ update_stmt_if_modified (bsi_stmt (bsi));
+ }
+
/* Debugging dumps. */
if (dump_file)
{
- dump_referenced_vars (dump_file);
+ dump_mem_ref_stats (dump_file);
+ dump_alias_info (dump_file);
+ dump_points_to_info (dump_file);
+
if (dump_flags & TDF_STATS)
dump_alias_stats (dump_file);
- dump_points_to_info (dump_file);
- dump_alias_info (dump_file);
+
+ if (dump_flags & TDF_DETAILS)
+ dump_referenced_vars (dump_file);
}
- /* Set up is_aliased flags. */
- compute_is_aliased ();
-
+ /* Report strict aliasing violations. */
+ strict_aliasing_warning_backend ();
+
/* Deallocate memory used by aliasing data structures. */
delete_alias_info (ai);
- {
- block_stmt_iterator bsi;
- basic_block bb;
- FOR_EACH_BB (bb)
- {
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
- {
- update_stmt_if_modified (bsi_stmt (bsi));
- }
- }
- }
+ if (need_ssa_update_p ())
+ update_ssa (TODO_update_ssa);
+
+ timevar_pop (TV_TREE_MAY_ALIAS);
+
return 0;
}
-
-struct tree_opt_pass pass_may_alias =
-{
- "alias", /* name */
- NULL, /* gate */
- compute_may_aliases, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_TREE_MAY_ALIAS, /* tv_id */
- PROP_cfg | PROP_ssa, /* properties_required */
- PROP_alias, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func | TODO_update_ssa
- | TODO_ggc_collect | TODO_verify_ssa
- | TODO_verify_stmts, /* todo_flags_finish */
- 0 /* letter */
-};
-
-
/* Data structure used to count the number of dereferences to PTR
inside an expression. */
struct count_ptr_d
/* Count the number of direct and indirect uses for pointer PTR in
- statement STMT. The two counts are stored in *NUM_USES_P and
- *NUM_DEREFS_P respectively. *IS_STORE_P is set to 'true' if at
- least one of those dereferences is a store operation. */
+ statement STMT. The number of direct uses is stored in
+ *NUM_USES_P. Indirect references are counted separately depending
+ on whether they are store or load operations. The counts are
+ stored in *NUM_STORES_P and *NUM_LOADS_P. */
void
count_uses_and_derefs (tree ptr, tree stmt, unsigned *num_uses_p,
- unsigned *num_derefs_p, bool *is_store)
+ unsigned *num_loads_p, unsigned *num_stores_p)
{
ssa_op_iter i;
tree use;
*num_uses_p = 0;
- *num_derefs_p = 0;
- *is_store = false;
+ *num_loads_p = 0;
+ *num_stores_p = 0;
/* Find out the total number of uses of PTR in STMT. */
FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
rhs = stmt;
}
- if (lhs && (TREE_CODE (lhs) == TREE_LIST
- || EXPR_P (lhs) || GIMPLE_STMT_P (lhs)))
+ if (lhs
+ && (TREE_CODE (lhs) == TREE_LIST
+ || EXPR_P (lhs)
+ || GIMPLE_STMT_P (lhs)))
{
struct count_ptr_d count;
count.ptr = ptr;
count.count = 0;
walk_tree (&lhs, count_ptr_derefs, &count, NULL);
- *is_store = true;
- *num_derefs_p = count.count;
+ *num_stores_p = count.count;
}
- if (rhs && (TREE_CODE (rhs) == TREE_LIST
- || EXPR_P (rhs) || GIMPLE_STMT_P (rhs)))
+ if (rhs
+ && (TREE_CODE (rhs) == TREE_LIST
+ || EXPR_P (rhs)
+ || GIMPLE_STMT_P (rhs)))
{
struct count_ptr_d count;
count.ptr = ptr;
count.count = 0;
walk_tree (&rhs, count_ptr_derefs, &count, NULL);
- *num_derefs_p += count.count;
+ *num_loads_p = count.count;
+ }
+ }
+
+ gcc_assert (*num_uses_p >= *num_loads_p + *num_stores_p);
+}
+
+/* Remove memory references stats for function FN. */
+
+void
+delete_mem_ref_stats (struct function *fn)
+{
+ if (gimple_mem_ref_stats (fn)->mem_sym_stats)
+ {
+ free_alloc_pool (mem_sym_stats_pool);
+ pointer_map_destroy (gimple_mem_ref_stats (fn)->mem_sym_stats);
+ }
+ gimple_mem_ref_stats (fn)->mem_sym_stats = NULL;
+}
+
+
+/* Initialize memory reference stats. */
+
+static void
+init_mem_ref_stats (void)
+{
+ struct mem_ref_stats_d *mem_ref_stats = gimple_mem_ref_stats (cfun);
+
+ mem_sym_stats_pool = create_alloc_pool ("Mem sym stats",
+ sizeof (struct mem_sym_stats_d),
+ 100);
+ memset (mem_ref_stats, 0, sizeof (struct mem_ref_stats_d));
+ mem_ref_stats->mem_sym_stats = pointer_map_create ();
+}
+
+
+/* Helper for init_alias_info. Reset existing aliasing information. */
+
+static void
+reset_alias_info (void)
+{
+ referenced_var_iterator rvi;
+ tree var;
+ unsigned i;
+ bitmap active_nmts, all_nmts;
+
+ /* Clear the set of addressable variables. We do not need to clear
+ the TREE_ADDRESSABLE bit on every symbol because we are going to
+ re-compute addressability here. */
+ bitmap_clear (gimple_addressable_vars (cfun));
+
+ active_nmts = BITMAP_ALLOC (&alias_bitmap_obstack);
+ all_nmts = BITMAP_ALLOC (&alias_bitmap_obstack);
+
+ /* Clear flow-insensitive alias information from each symbol. */
+ FOR_EACH_REFERENCED_VAR (var, rvi)
+ {
+ if (is_gimple_reg (var))
+ continue;
+
+ if (MTAG_P (var))
+ MTAG_ALIASES (var) = NULL;
+
+ /* Memory partition information will be computed from scratch. */
+ if (TREE_CODE (var) == MEMORY_PARTITION_TAG)
+ MPT_SYMBOLS (var) = NULL;
+
+ /* Collect all the name tags to determine if we have any
+ orphaned that need to be removed from the IL. A name tag
+ will be orphaned if it is not associated with any active SSA
+ name. */
+ if (TREE_CODE (var) == NAME_MEMORY_TAG)
+ bitmap_set_bit (all_nmts, DECL_UID (var));
+
+ /* Since we are about to re-discover call-clobbered
+ variables, clear the call-clobbered flag. Variables that
+ are intrinsically call-clobbered (globals, local statics,
+ etc) will not be marked by the aliasing code, so we can't
+ remove them from CALL_CLOBBERED_VARS.
+
+ NB: STRUCT_FIELDS are still call clobbered if they are for a
+ global variable, so we *don't* clear their call clobberedness
+ just because they are tags, though we will clear it if they
+ aren't for global variables. */
+ if (TREE_CODE (var) == NAME_MEMORY_TAG
+ || TREE_CODE (var) == SYMBOL_MEMORY_TAG
+ || TREE_CODE (var) == MEMORY_PARTITION_TAG
+ || !is_global_var (var))
+ clear_call_clobbered (var);
+ }
+
+ /* Clear flow-sensitive points-to information from each SSA name. */
+ for (i = 1; i < num_ssa_names; i++)
+ {
+ tree name = ssa_name (i);
+
+ if (!name || !POINTER_TYPE_P (TREE_TYPE (name)))
+ continue;
+
+ if (SSA_NAME_PTR_INFO (name))
+ {
+ struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
+
+ /* Clear all the flags but keep the name tag to
+ avoid creating new temporaries unnecessarily. If
+ this pointer is found to point to a subset or
+ superset of its former points-to set, then a new
+ tag will need to be created in create_name_tags. */
+ pi->pt_anything = 0;
+ pi->pt_null = 0;
+ pi->value_escapes_p = 0;
+ pi->is_dereferenced = 0;
+ if (pi->pt_vars)
+ bitmap_clear (pi->pt_vars);
+
+ /* Add NAME's name tag to the set of active tags. */
+ if (pi->name_mem_tag)
+ bitmap_set_bit (active_nmts, DECL_UID (pi->name_mem_tag));
}
}
- gcc_assert (*num_uses_p >= *num_derefs_p);
+ /* Name memory tags that are no longer associated with an SSA name
+ are considered stale and should be removed from the IL. All the
+ name tags that are in the set ALL_NMTS but not in ACTIVE_NMTS are
+ considered stale and marked for renaming. */
+ bitmap_and_compl_into (all_nmts, active_nmts);
+ mark_set_for_renaming (all_nmts);
+
+ BITMAP_FREE (all_nmts);
+ BITMAP_FREE (active_nmts);
}
+
/* Initialize the data structures used for alias analysis. */
static struct alias_info *
ai->dereferenced_ptrs_store = pointer_set_create ();
ai->dereferenced_ptrs_load = pointer_set_create ();
+ /* Clear out all memory reference stats. */
+ init_mem_ref_stats ();
+
/* If aliases have been computed before, clear existing information. */
if (gimple_aliases_computed_p (cfun))
- {
- unsigned i;
-
- bitmap_obstack_release (&alias_bitmap_obstack);
-
- /* Similarly, clear the set of addressable variables. In this
- case, we can just clear the set because addressability is
- only computed here. */
- bitmap_clear (gimple_addressable_vars (cfun));
-
- /* Clear flow-insensitive alias information from each symbol. */
- FOR_EACH_REFERENCED_VAR (var, rvi)
- {
- var_ann_t ann = var_ann (var);
-
- ann->is_aliased = 0;
-
- if (MTAG_P (var))
- MTAG_ALIASES (var) = NULL;
-
- /* Since we are about to re-discover call-clobbered
- variables, clear the call-clobbered flag. Variables that
- are intrinsically call-clobbered (globals, local statics,
- etc) will not be marked by the aliasing code, so we can't
- remove them from CALL_CLOBBERED_VARS.
-
- NB: STRUCT_FIELDS are still call clobbered if they are for
- a global variable, so we *don't* clear their call clobberedness
- just because they are tags, though we will clear it if they
- aren't for global variables. */
- if (TREE_CODE (var) == NAME_MEMORY_TAG
- || TREE_CODE (var) == SYMBOL_MEMORY_TAG
- || !is_global_var (var))
- clear_call_clobbered (var);
- }
-
- /* Clear flow-sensitive points-to information from each SSA name. */
- for (i = 1; i < num_ssa_names; i++)
- {
- tree name = ssa_name (i);
-
- if (!name || !POINTER_TYPE_P (TREE_TYPE (name)))
- continue;
-
- if (SSA_NAME_PTR_INFO (name))
- {
- struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
-
- /* Clear all the flags but keep the name tag to
- avoid creating new temporaries unnecessarily. If
- this pointer is found to point to a subset or
- superset of its former points-to set, then a new
- tag will need to be created in create_name_tags. */
- pi->pt_anything = 0;
- pi->pt_null = 0;
- pi->value_escapes_p = 0;
- pi->is_dereferenced = 0;
- if (pi->pt_vars)
- bitmap_clear (pi->pt_vars);
- }
- }
- }
+ reset_alias_info ();
else
{
/* If this is the first time we compute aliasing information,
/* Next time, we will need to reset alias information. */
cfun->gimple_df->aliases_computed_p = true;
+ if (alias_bitmap_obstack.elements != NULL)
+ bitmap_obstack_release (&alias_bitmap_obstack);
bitmap_obstack_initialize (&alias_bitmap_obstack);
return ai;
pointer_set_destroy (ai->dereferenced_ptrs_load);
free (ai);
+ delete_mem_ref_stats (cfun);
delete_points_to_sets ();
}
+
/* Used for hashing to identify pointer infos with identical
pt_vars bitmaps. */
+
static int
eq_ptr_info (const void *p1, const void *p2)
{
return bitmap_hash (n->pt_vars);
}
+
/* Create name tags for all the pointers that have been dereferenced.
We only create a name tag for a pointer P if P is found to point to
a set of variables (so that we can alias them to *P) or if it is
return;
ptr_hash = htab_create (10, ptr_info_hash, eq_ptr_info, NULL);
+
/* Now go through the pointers with pt_vars, and find a name tag
with the same pt_vars as this pointer, or create one if one
doesn't exist. */
problems if they both had different name tags because
they would have different SSA version numbers (which
would force us to take the name tags in and out of SSA). */
-
slot = (struct ptr_info_def **) htab_find_slot (ptr_hash, pi, INSERT);
if (*slot)
pi->name_mem_tag = (*slot)->name_mem_tag;
else
{
*slot = pi;
+
/* If we didn't find a pointer with the same points-to set
as PTR, create a new name tag if needed. */
if (pi->name_mem_tag == NULL_TREE)
renaming. */
if (old_name_tag && old_name_tag != pi->name_mem_tag)
mark_sym_for_renaming (old_name_tag);
-
+
+ /* Inherit volatility from the pointed-to type. */
TREE_THIS_VOLATILE (pi->name_mem_tag)
- |= TREE_THIS_VOLATILE (TREE_TYPE (TREE_TYPE (ptr)));
+ |= TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (ptr)));
/* Mark the new name tag for renaming. */
mark_sym_for_renaming (pi->name_mem_tag);
}
+
htab_delete (ptr_hash);
VEC_free (tree, heap, with_ptvars);
}
-/* Union the alias set SET into the may-aliases for TAG */
+
+/* Union the alias set SET into the may-aliases for TAG. */
static void
union_alias_set_into (tree tag, bitmap set)
size_t i;
tree ptr;
+ timevar_push (TV_FLOW_SENSITIVE);
set_used_smts ();
for (i = 0; VEC_iterate (tree, ai->processed_ptrs, i, ptr); i++)
}
}
}
+ timevar_pop (TV_FLOW_SENSITIVE);
}
{
size_t i;
+ timevar_push (TV_FLOW_INSENSITIVE);
/* For every pointer P, determine which addressable variables may alias
with P's symbol memory tag. */
for (i = 0; i < ai->num_pointers; i++)
}
}
+ timevar_pop (TV_FLOW_INSENSITIVE);
}
for (i = 0; i < ai->num_pointers; i++)
{
tree ptr = ai->pointers[i]->var, tag;
+ /* Avoid adding to self and clean up. */
if (PTR_IS_REF_ALL (ptr))
- continue;
+ {
+ struct ptr_info_def *pi = get_ptr_info (ptr);
+ if (pi->is_dereferenced)
+ pi->pt_anything = 0;
+ continue;
+ }
tag = symbol_mem_tag (ptr);
if (is_call_clobbered (tag))
add_may_alias (ai->ref_all_symbol_mem_tag, tag);
if (var_can_have_subvars (var)
&& (svars = get_subvars_for_var (var)))
{
- subvar_t sv;
+ unsigned int i;
+ tree subvar;
- for (sv = svars; sv; sv = sv->next)
+ for (i = 0; VEC_iterate (tree, svars, i, subvar); ++i)
{
if (bitmap_bit_p (gimple_addressable_vars (cfun),
- DECL_UID (sv->var)))
+ DECL_UID (subvar)))
okay_to_mark = false;
- mark_sym_for_renaming (sv->var);
+ mark_sym_for_renaming (subvar);
}
}
to represent all possible global memory referenced by the callee. */
static void
-maybe_create_global_var (struct alias_info *ai)
+maybe_create_global_var (void)
{
/* No need to create it, if we have one already. */
if (gimple_global_var (cfun) == NULL_TREE)
{
+ struct mem_ref_stats_d *stats = gimple_mem_ref_stats (cfun);
+
/* Create .GLOBAL_VAR if there are no call-clobbered
variables and the program contains a mixture of pure/const
and regular function calls. This is to avoid the problem
So, if we have some pure/const and some regular calls in the
program we create .GLOBAL_VAR to avoid missing these
relations. */
- if (bitmap_count_bits (gimple_call_clobbered_vars (cfun)) == 0
- && ai->num_calls_found > 0
- && ai->num_pure_const_calls_found > 0
- && ai->num_calls_found > ai->num_pure_const_calls_found)
+ if (bitmap_empty_p (gimple_call_clobbered_vars (cfun))
+ && stats->num_call_sites > 0
+ && stats->num_pure_const_call_sites > 0
+ && stats->num_call_sites > stats->num_pure_const_call_sites)
create_global_var ();
}
}
VAR_ALIAS_SET is the alias set for VAR. */
static bool
-may_alias_p (tree ptr, HOST_WIDE_INT mem_alias_set,
- tree var, HOST_WIDE_INT var_alias_set,
+may_alias_p (tree ptr, alias_set_type mem_alias_set,
+ tree var, alias_set_type var_alias_set,
bool alias_set_only)
{
tree mem;
gcc_assert (TREE_CODE (mem) == SYMBOL_MEMORY_TAG);
- alias_stats.tbaa_queries++;
-
- /* If the alias sets don't conflict then MEM cannot alias VAR. */
- if (!alias_sets_conflict_p (mem_alias_set, var_alias_set))
+ if (!DECL_NO_TBAA_P (ptr))
{
- alias_stats.alias_noalias++;
- alias_stats.tbaa_resolved++;
- return false;
- }
+ alias_stats.tbaa_queries++;
- /* If VAR is a record or union type, PTR cannot point into VAR
- unless there is some explicit address operation in the
- program that can reference a field of the type pointed-to by PTR.
- This also assumes that the types of both VAR and PTR are
- contained within the compilation unit, and that there is no fancy
- addressing arithmetic associated with any of the types
- involved. */
- if (mem_alias_set != 0 && var_alias_set != 0)
- {
- tree ptr_type = TREE_TYPE (ptr);
- tree var_type = TREE_TYPE (var);
-
- /* The star count is -1 if the type at the end of the pointer_to
- chain is not a record or union type. */
- if ((!alias_set_only) &&
- ipa_type_escape_star_count_of_interesting_type (var_type) >= 0)
+ /* If the alias sets don't conflict then MEM cannot alias VAR. */
+ if (!alias_sets_conflict_p (mem_alias_set, var_alias_set))
{
- int ptr_star_count = 0;
-
- /* ipa_type_escape_star_count_of_interesting_type is a
- little too restrictive for the pointer type, need to
- allow pointers to primitive types as long as those types
- cannot be pointers to everything. */
- while (POINTER_TYPE_P (ptr_type))
+ alias_stats.alias_noalias++;
+ alias_stats.tbaa_resolved++;
+ return false;
+ }
+
+ /* If VAR is a record or union type, PTR cannot point into VAR
+ unless there is some explicit address operation in the
+ program that can reference a field of the type pointed-to by
+ PTR. This also assumes that the types of both VAR and PTR
+ are contained within the compilation unit, and that there is
+ no fancy addressing arithmetic associated with any of the
+ types involved. */
+ if (mem_alias_set != 0 && var_alias_set != 0)
+ {
+ tree ptr_type = TREE_TYPE (ptr);
+ tree var_type = TREE_TYPE (var);
+
+ /* The star count is -1 if the type at the end of the
+ pointer_to chain is not a record or union type. */
+ if ((!alias_set_only) &&
+ ipa_type_escape_star_count_of_interesting_type (var_type) >= 0)
{
- /* Strip the *s off. */
- ptr_type = TREE_TYPE (ptr_type);
- ptr_star_count++;
- }
+ int ptr_star_count = 0;
- /* There does not appear to be a better test to see if the
- pointer type was one of the pointer to everything
- types. */
- if (ptr_star_count > 0)
- {
- alias_stats.structnoaddress_queries++;
- if (ipa_type_escape_field_does_not_clobber_p (var_type,
- TREE_TYPE (ptr)))
+ /* ipa_type_escape_star_count_of_interesting_type is a
+ little too restrictive for the pointer type, need to
+ allow pointers to primitive types as long as those
+ types cannot be pointers to everything. */
+ while (POINTER_TYPE_P (ptr_type))
+ {
+ /* Strip the *s off. */
+ ptr_type = TREE_TYPE (ptr_type);
+ ptr_star_count++;
+ }
+
+ /* There does not appear to be a better test to see if
+ the pointer type was one of the pointer to everything
+ types. */
+ if (ptr_star_count > 0)
+ {
+ alias_stats.structnoaddress_queries++;
+ if (ipa_type_escape_field_does_not_clobber_p (var_type,
+ TREE_TYPE (ptr)))
+ {
+ alias_stats.structnoaddress_resolved++;
+ alias_stats.alias_noalias++;
+ return false;
+ }
+ }
+ else if (ptr_star_count == 0)
{
+ /* If PTR_TYPE was not really a pointer to type, it cannot
+ alias. */
+ alias_stats.structnoaddress_queries++;
alias_stats.structnoaddress_resolved++;
alias_stats.alias_noalias++;
return false;
}
}
- else if (ptr_star_count == 0)
- {
- /* If PTR_TYPE was not really a pointer to type, it cannot
- alias. */
- alias_stats.structnoaddress_queries++;
- alias_stats.structnoaddress_resolved++;
- alias_stats.alias_noalias++;
- return false;
- }
}
}
static void
add_may_alias (tree var, tree alias)
{
-
/* Don't allow self-referential aliases. */
gcc_assert (var != alias);
size_t i;
tree tag;
tree tag_type = TREE_TYPE (TREE_TYPE (ptr));
- HOST_WIDE_INT tag_set = get_alias_set (tag_type);
+ alias_set_type tag_set = get_alias_set (tag_type);
/* We use a unique memory tag for all the ref-all pointers. */
if (PTR_IS_REF_ALL (ptr))
referenced_var_iterator rvi;
tree var;
+ fprintf (file, "\nAlias information for %s\n\n", funcname);
+
+ dump_memory_partitions (file);
+
fprintf (file, "\nFlow-insensitive alias information for %s\n\n", funcname);
fprintf (file, "Aliased symbols\n\n");
dump_variable (file, var);
}
- dump_memory_partitions (file);
-
fprintf (file, "\n");
}
tree stmt = bsi_stmt (si);
tree def;
FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
- if (POINTER_TYPE_P (TREE_TYPE (def)))
+ if (TREE_CODE (def) == SSA_NAME
+ && POINTER_TYPE_P (TREE_TYPE (def)))
dump_points_to_info_for (file, def);
}
}
return true;
}
-
-/* Given two symbols return TRUE if one is in the alias set of the
- other. */
-
-bool
-is_aliased_with (tree tag, tree sym)
-{
- bitmap aliases;
-
- if (MTAG_P (tag))
- {
- aliases = MTAG_ALIASES (tag);
-
- if (aliases == NULL)
- return false;
-
- return bitmap_bit_p (aliases, DECL_UID (sym));
- }
- else
- {
- gcc_assert (MTAG_P (sym));
- aliases = MTAG_ALIASES (sym);
-
- if (aliases == NULL)
- return false;
-
- return bitmap_bit_p (aliases, DECL_UID (tag));
- }
-
- return false;
-}
-
/* The following is based on code in add_stmt_operand to ensure that the
same defs/uses/vdefs/vuses will be found after replacing a reference
to var (or ARRAY_REF to var) with an INDIRECT_REF to ptr whose value
aliases = may_aliases (var);
/* Case 1: |aliases| == 1 */
- if (aliases && bitmap_count_bits (aliases) == 1)
+ if (aliases
+ && bitmap_single_bit_set_p (aliases))
{
tree ali = referenced_var (bitmap_first_set_bit (aliases));
if (TREE_CODE (ali) == SYMBOL_MEMORY_TAG)
HOST_WIDE_INT offset, size, maxsize;
tree ref;
VEC (tree, heap) *overlaps = NULL;
- subvar_t sv;
- unsigned int len;
+ unsigned int len, i;
+ tree subvar;
+
gcc_assert (symbol_mem_tag (ptr) == NULL_TREE);
gcc_assert (!MTAG_P (var));
if (var_can_have_subvars (ref)
&& (svars = get_subvars_for_var (ref)))
{
- for (sv = svars; sv; sv = sv->next)
+ for (i = 0; VEC_iterate (tree, svars, i, subvar); ++i)
{
bool exact;
- if (overlap_subvar (offset, maxsize, sv->var, &exact))
- VEC_safe_push (tree, heap, overlaps, sv->var);
+ if (overlap_subvar (offset, maxsize, subvar, &exact))
+ VEC_safe_push (tree, heap, overlaps, subvar);
}
gcc_assert (overlaps != NULL);
}
On mem-ssa branch, the scanning for virtual operands have been
split from the rest of tree-ssa-operands, so it should be much
easier to fix this problem correctly once mem-ssa is merged. */
- for (sv = svars; sv; sv = sv->next)
- VEC_safe_push (tree, heap, overlaps, sv->var);
+ for (i = 0; VEC_iterate (tree, svars, i, subvar); ++i)
+ VEC_safe_push (tree, heap, overlaps, subvar);
gcc_assert (overlaps != NULL);
}
/* Create and return a structure sub-variable for field type FIELD at
- offset OFFSET, with size SIZE, of variable VAR. */
+ offset OFFSET, with size SIZE, of variable VAR. If ALIAS_SET not
+ -1 this field is non-addressable and we should use this alias set
+ with this field. */
static tree
create_sft (tree var, tree field, unsigned HOST_WIDE_INT offset,
- unsigned HOST_WIDE_INT size)
+ unsigned HOST_WIDE_INT size, alias_set_type alias_set,
+ bool base_for_components)
{
tree subvar = create_tag_raw (STRUCT_FIELD_TAG, field, "SFT");
SFT_PARENT_VAR (subvar) = var;
SFT_OFFSET (subvar) = offset;
SFT_SIZE (subvar) = size;
+ SFT_ALIAS_SET (subvar) = alias_set;
+ SFT_BASE_FOR_COMPONENTS_P (subvar) = base_for_components;
+ SFT_UNPARTITIONABLE_P (subvar) = false;
+
return subvar;
}
|| up->write_only)
return;
- push_fields_onto_fieldstack (TREE_TYPE (var), &fieldstack, 0, NULL);
- if (VEC_length (fieldoff_s, fieldstack) != 0)
+ push_fields_onto_fieldstack (TREE_TYPE (var), &fieldstack, 0, NULL,
+ TREE_TYPE (var));
+ /* Make sure to not create SFTs for structs we won't generate variable
+ infos for. See tree-ssa-structalias.c:create_variable_info_for (). */
+ if (VEC_length (fieldoff_s, fieldstack) > 1
+ && VEC_length (fieldoff_s, fieldstack) <= MAX_FIELDS_FOR_FIELD_SENSITIVE)
{
subvar_t *subvars;
fieldoff_s *fo;
/* Otherwise, create the variables. */
subvars = lookup_subvars_for_var (var);
-
+ *subvars = VEC_alloc (tree, gc, VEC_length (fieldoff_s, fieldstack));
+
sort_fieldstack (fieldstack);
- for (i = VEC_length (fieldoff_s, fieldstack);
- VEC_iterate (fieldoff_s, fieldstack, --i, fo);)
+ for (i = 0; VEC_iterate (fieldoff_s, fieldstack, i, fo); ++i)
{
- subvar_t sv;
HOST_WIDE_INT fosize;
- tree currfotype;
+ tree currfotype, subvar;
fosize = TREE_INT_CST_LOW (fo->size);
currfotype = fo->type;
/* If this field isn't in the used portion,
or it has the exact same offset and size as the last
- field, skip it. */
-
- if (((fo->offset <= up->minused
- && fo->offset + fosize <= up->minused)
- || fo->offset >= up->maxused)
+ field, skip it. Note that we always need the field at
+ offset 0 so we can properly handle pointers to the
+ structure. */
+
+ if ((fo->offset != 0
+ && ((fo->offset <= up->minused
+ && fo->offset + fosize <= up->minused)
+ || fo->offset >= up->maxused))
|| (fo->offset == lastfooffset
&& fosize == lastfosize
&& currfotype == lastfotype))
continue;
- sv = GGC_NEW (struct subvar);
- sv->next = *subvars;
- sv->var = create_sft (var, fo->type, fo->offset, fosize);
+ subvar = create_sft (var, fo->type, fo->offset,
+ fosize, fo->alias_set, fo->base_for_components);
+ VEC_quick_push (tree, *subvars, subvar);
if (dump_file)
{
fprintf (dump_file, "structure field tag %s created for var %s",
- get_name (sv->var), get_name (var));
+ get_name (subvar), get_name (var));
fprintf (dump_file, " offset " HOST_WIDE_INT_PRINT_DEC,
- SFT_OFFSET (sv->var));
+ SFT_OFFSET (subvar));
fprintf (dump_file, " size " HOST_WIDE_INT_PRINT_DEC,
- SFT_SIZE (sv->var));
+ SFT_SIZE (subvar));
fprintf (dump_file, "\n");
}
lastfotype = currfotype;
lastfooffset = fo->offset;
lastfosize = fosize;
- *subvars = sv;
}
/* Once we have created subvars, the original is no longer call
break;
case CALL_EXPR:
{
- tree *arg;
- for (arg = &TREE_OPERAND (*tp, 1); *arg; arg = &TREE_CHAIN (*arg))
+ int i;
+ int nargs = call_expr_nargs (*tp);
+ for (i = 0; i < nargs; i++)
{
- if (TREE_CODE (TREE_VALUE (*arg)) != ADDR_EXPR)
- find_used_portions (&TREE_VALUE (*arg), walk_subtrees, NULL);
+ tree *arg = &CALL_EXPR_ARG (*tp, i);
+ if (TREE_CODE (*arg) == ADDR_EXPR)
+ find_used_portions (arg, walk_subtrees, NULL);
}
*walk_subtrees = 0;
return NULL_TREE;
FOR_EACH_BB (bb)
{
block_stmt_iterator bsi;
+ tree phi;
+
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ {
+ use_operand_p use;
+ ssa_op_iter iter;
+
+ FOR_EACH_PHI_ARG (use, phi, iter, SSA_OP_USE)
+ {
+ tree op = USE_FROM_PTR (use);
+ walk_tree_without_duplicates (&op, find_used_portions,
+ NULL);
+ }
+ }
+
for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
{
walk_tree_without_duplicates (bsi_stmt_ptr (bsi),
tree sym = referenced_var_lookup (i);
if (get_subvars_for_var (sym))
{
- update=true;
+ update = true;
break;
}
}
tree sym = referenced_var_lookup (i);
if (get_subvars_for_var (sym))
{
- update=true;
+ update = true;
break;
}
}
tree sym = referenced_var_lookup (i);
if (get_subvars_for_var (sym))
{
- update=true;
+ update = true;
break;
}
}
update_stmt (stmt);
}
}
-
- return 0;
+
+ return TODO_rebuild_alias;
}
static bool
0, /* todo_flags_finish */
0 /* letter */
};
+
+static bool
+gate_build_alias (void)
+{
+ return !gate_structure_vars();
+}
+
+
+struct tree_opt_pass pass_build_alias =
+{
+ "build_alias", /* name */
+ gate_build_alias, /* gate */
+ NULL, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ 0, /* tv_id */
+ PROP_cfg | PROP_ssa, /* properties_required */
+ PROP_alias, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_rebuild_alias, /* todo_flags_finish */
+ 0 /* letter */
+};
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