/* Alias analysis for trees.
- Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009
+ 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 "function.h"
#include "diagnostic.h"
#include "tree-dump.h"
-#include "tree-gimple.h"
+#include "gimple.h"
#include "tree-flow.h"
#include "tree-inline.h"
#include "tree-pass.h"
-#include "tree-ssa-structalias.h"
#include "convert.h"
#include "params.h"
#include "ipa-type-escape.h"
#include "bitmap.h"
#include "vecprim.h"
#include "pointer-set.h"
+#include "alloc-pool.h"
+#include "tree-ssa-alias.h"
-/* Structure to map a variable to its alias set. */
-struct alias_map_d
-{
- /* Variable and its alias set. */
- tree var;
- HOST_WIDE_INT 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
-{
- unsigned int alias_queries;
- unsigned int alias_mayalias;
- unsigned int alias_noalias;
- unsigned int simple_queries;
- unsigned int simple_resolved;
- unsigned int tbaa_queries;
- unsigned int tbaa_resolved;
- unsigned int structnoaddress_queries;
- unsigned int structnoaddress_resolved;
-};
-
-
-/* Local variables. */
-static struct alias_stats_d alias_stats;
-static bitmap_obstack alias_bitmap_obstack;
-
-/* Local functions. */
-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 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 add_may_alias (tree, tree);
-static struct alias_info *init_alias_info (void);
-static void delete_alias_info (struct alias_info *);
-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);
-
-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);
-
-/* Global declarations. */
-
-/* Mark variable VAR as being non-addressable. */
-
-static void
-mark_non_addressable (tree var)
-{
- tree mpt;
-
- if (!TREE_ADDRESSABLE (var))
- return;
-
- mpt = memory_partition (var);
-
- if (!MTAG_P (var))
- var_ann (var)->call_clobbered = false;
-
- bitmap_clear_bit (gimple_call_clobbered_vars (cfun), DECL_UID (var));
- TREE_ADDRESSABLE (var) = 0;
-
- if (mpt)
- {
- bitmap_clear_bit (MPT_SYMBOLS (mpt), DECL_UID (var));
- set_memory_partition (var, NULL_TREE);
- }
-}
-
-
-/* qsort comparison function to sort type/name tags by DECL_UID. */
-
-static int
-sort_tags_by_id (const void *pa, const void *pb)
-{
- tree a = *(tree *)pa;
- tree b = *(tree *)pb;
-
- return DECL_UID (a) - DECL_UID (b);
-}
-
-/* Initialize WORKLIST to contain those memory tags that are marked call
- clobbered. Initialized WORKLIST2 to contain the reasons these
- memory tags escaped. */
-
-static void
-init_transitive_clobber_worklist (VEC (tree, heap) **worklist,
- VEC (int, heap) **worklist2)
-{
- referenced_var_iterator rvi;
- tree curr;
-
- FOR_EACH_REFERENCED_VAR (curr, rvi)
- {
- 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);
- }
- }
-}
-
-/* Add ALIAS to WORKLIST (and the reason for escaping REASON to WORKLIST2) if
- ALIAS is not already marked call clobbered, and is a memory
- tag. */
-
-static void
-add_to_worklist (tree alias, VEC (tree, heap) **worklist,
- VEC (int, heap) **worklist2,
- int reason)
-{
- if (MTAG_P (alias) && !is_call_clobbered (alias))
- {
- VEC_safe_push (tree, heap, *worklist, alias);
- VEC_safe_push (int, heap, *worklist2, reason);
- }
-}
-
-/* Mark aliases of TAG as call clobbered, and place any tags on the
- alias list that were not already call clobbered on WORKLIST. */
-
-static void
-mark_aliases_call_clobbered (tree tag, VEC (tree, heap) **worklist,
- VEC (int, heap) **worklist2)
-{
- bitmap aliases;
- bitmap_iterator bi;
- unsigned int i;
- tree entry;
- var_ann_t ta = var_ann (tag);
-
- if (!MTAG_P (tag))
- return;
- aliases = may_aliases (tag);
- if (!aliases)
- return;
-
- EXECUTE_IF_SET_IN_BITMAP (aliases, 0, i, bi)
- {
- entry = referenced_var (i);
- if (!unmodifiable_var_p (entry))
- {
- add_to_worklist (entry, worklist, worklist2, ta->escape_mask);
- mark_call_clobbered (entry, ta->escape_mask);
- }
- }
-}
-
-/* Tags containing global vars need to be marked as global.
- Tags containing call clobbered vars need to be marked as call
- clobbered. */
-
-static void
-compute_tag_properties (void)
-{
- referenced_var_iterator rvi;
- tree tag;
- bool changed = true;
- VEC (tree, heap) *taglist = NULL;
-
- FOR_EACH_REFERENCED_VAR (tag, rvi)
- {
- if (!MTAG_P (tag) || TREE_CODE (tag) == STRUCT_FIELD_TAG)
- continue;
- VEC_safe_push (tree, heap, taglist, tag);
- }
-
- /* We sort the taglist by DECL_UID, for two reasons.
- 1. To get a sequential ordering to make the bitmap accesses
- faster.
- 2. Because of the way we compute aliases, it's more likely that
- an earlier tag is included in a later tag, and this will reduce
- the number of iterations.
-
- If we had a real tag graph, we would just topo-order it and be
- done with it. */
- qsort (VEC_address (tree, taglist),
- VEC_length (tree, taglist),
- sizeof (tree),
- sort_tags_by_id);
-
- /* Go through each tag not marked as global, and if it aliases
- global vars, mark it global.
-
- If the tag contains call clobbered vars, mark it call
- clobbered.
-
- This loop iterates because tags may appear in the may-aliases
- list of other tags when we group. */
-
- while (changed)
- {
- unsigned int k;
-
- changed = false;
- for (k = 0; VEC_iterate (tree, taglist, k, tag); k++)
- {
- bitmap ma;
- bitmap_iterator bi;
- unsigned int i;
- tree entry;
- bool tagcc = is_call_clobbered (tag);
- bool tagglobal = MTAG_GLOBAL (tag);
-
- if (tagcc && tagglobal)
- continue;
-
- ma = may_aliases (tag);
- if (!ma)
- continue;
-
- EXECUTE_IF_SET_IN_BITMAP (ma, 0, i, bi)
- {
- entry = referenced_var (i);
- /* Call clobbered entries cause the tag to be marked
- call clobbered. */
- if (!tagcc && is_call_clobbered (entry))
- {
- mark_call_clobbered (tag, var_ann (entry)->escape_mask);
- tagcc = true;
- changed = true;
- }
-
- /* Global vars cause the tag to be marked global. */
- if (!tagglobal && is_global_var (entry))
- {
- MTAG_GLOBAL (tag) = true;
- changed = true;
- tagglobal = true;
- }
-
- /* Early exit once both global and cc are set, since the
- loop can't do any more than that. */
- if (tagcc && tagglobal)
- break;
- }
- }
- }
- VEC_free (tree, heap, taglist);
-}
-
-/* Set up the initial variable clobbers and globalness.
- When this function completes, only tags whose aliases need to be
- clobbered will be set clobbered. Tags clobbered because they
- contain call clobbered vars are handled in compute_tag_properties. */
-
-static void
-set_initial_properties (struct alias_info *ai)
-{
- unsigned int i;
- referenced_var_iterator rvi;
- tree var;
- tree ptr;
-
- FOR_EACH_REFERENCED_VAR (var, rvi)
- {
- if (is_global_var (var)
- && (!var_can_have_subvars (var)
- || get_subvars_for_var (var) == NULL))
- {
- if (!unmodifiable_var_p (var))
- mark_call_clobbered (var, ESCAPE_IS_GLOBAL);
- }
- else if (TREE_CODE (var) == PARM_DECL
- && gimple_default_def (cfun, var)
- && POINTER_TYPE_P (TREE_TYPE (var)))
- {
- tree def = gimple_default_def (cfun, var);
- get_ptr_info (def)->value_escapes_p = 1;
- get_ptr_info (def)->escape_mask |= ESCAPE_IS_PARM;
- }
- }
-
- for (i = 0; VEC_iterate (tree, ai->processed_ptrs, i, ptr); i++)
- {
- struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
- tree tag = symbol_mem_tag (SSA_NAME_VAR (ptr));
-
- if (pi->value_escapes_p)
- {
- /* If PTR escapes then its associated memory tags and
- pointed-to variables are call-clobbered. */
- if (pi->name_mem_tag)
- mark_call_clobbered (pi->name_mem_tag, pi->escape_mask);
-
- if (tag)
- mark_call_clobbered (tag, pi->escape_mask);
-
- if (pi->pt_vars)
- {
- 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);
- }
- }
-
- /* If the name tag is call clobbered, so is the symbol tag
- associated with the base VAR_DECL. */
- if (pi->name_mem_tag
- && tag
- && is_call_clobbered (pi->name_mem_tag))
- mark_call_clobbered (tag, pi->escape_mask);
-
- /* Name tags and symbol tags that we don't know where they point
- to, might point to global memory, and thus, are clobbered.
-
- FIXME: This is not quite right. They should only be
- clobbered if value_escapes_p is true, regardless of whether
- they point to global memory or not.
- So removing this code and fixing all the bugs would be nice.
- It is the cause of a bunch of clobbering. */
- if ((pi->pt_global_mem || pi->pt_anything)
- && pi->is_dereferenced && pi->name_mem_tag)
- {
- mark_call_clobbered (pi->name_mem_tag, ESCAPE_IS_GLOBAL);
- MTAG_GLOBAL (pi->name_mem_tag) = true;
- }
-
- if ((pi->pt_global_mem || pi->pt_anything)
- && pi->is_dereferenced
- && tag)
- {
- mark_call_clobbered (tag, ESCAPE_IS_GLOBAL);
- MTAG_GLOBAL (tag) = true;
- }
- }
-}
-
-/* Compute which variables need to be marked call clobbered because
- their tag is call clobbered, and which tags need to be marked
- global because they contain global variables. */
-
-static void
-compute_call_clobbered (struct alias_info *ai)
-{
- VEC (tree, heap) *worklist = NULL;
- VEC(int,heap) *worklist2 = NULL;
-
- set_initial_properties (ai);
- init_transitive_clobber_worklist (&worklist, &worklist2);
- while (VEC_length (tree, worklist) != 0)
- {
- tree curr = VEC_pop (tree, worklist);
- int reason = VEC_pop (int, worklist2);
-
- mark_call_clobbered (curr, reason);
- mark_aliases_call_clobbered (curr, &worklist, &worklist2);
- }
- VEC_free (tree, heap, worklist);
- VEC_free (int, heap, worklist2);
- compute_tag_properties ();
-}
-
-/* Dump the MP_INFO array to FILE. */
-
-void
-dump_mp_info (FILE *file, VEC(mp_info_t,heap) *mp_info)
-{
- unsigned i;
- mp_info_t mp_p;
-
- for (i = 0; VEC_iterate (mp_info_t, mp_info, i, mp_p); i++)
- {
- fprintf (file, "%6lu\t", mp_p->num_vops);
- if (mp_p->var == NULL_TREE)
- {
- fprintf (file, "CALL-CLOBBERED SYMBOLS: ");
- dump_decl_set (file, gimple_call_clobbered_vars (cfun));
- }
- else
- dump_variable (file, mp_p->var);
- }
-}
-
-
-/* Dump the MP_INFO array to stderr. */
-
-void
-debug_mp_info (VEC(mp_info_t,heap) *mp_info)
-{
- dump_mp_info (stderr, mp_info);
-}
-
-
-/* Comparison function for qsort used in sort_mp_info. */
-
-static int
-mp_info_cmp (const void *p, const void *q)
-{
- mp_info_t e1 = *((const mp_info_t *) p);
- mp_info_t e2 = *((const mp_info_t *) q);
-
- /* We want to sort in decreasing order. */
- if (e1->num_vops < e2->num_vops)
- return 1;
- else if (e1->num_vops > e2->num_vops)
- return -1;
- else
- return 0;
-}
-
-
-/* Sort the array of reference counts used to compute memory partitions.
- Elements are sorted in descending order of virtual operators needed. */
-
-static inline void
-sort_mp_info (VEC(mp_info_t,heap) *list)
-{
- unsigned num = VEC_length (mp_info_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)
- {
- /* 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);
- }
-
- 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);
-}
-
-
-/* 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. */
-
-static void
-create_partition_for (mp_info_t mp_p)
-{
- bitmap_iterator bi;
- tree mpt, sym;
- bitmap aliases;
- unsigned i;
-
- if (mp_p->num_vops <= (long) MAX_ALIASED_VOPS)
- return;
-
- if (mp_p->var == NULL_TREE)
- {
- bitmap_iterator bi;
- bitmap tmp;
-
- /* 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));
-
- /* 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);
- }
-
- mp_p->num_vops--;
-
- /* If we have already grouped enough, stop. */
- if (mp_p->num_vops <= (long) MAX_ALIASED_VOPS)
- break;
- }
-
- BITMAP_FREE (tmp);
- }
- else
- {
- aliases = may_aliases (mp_p->var);
- gcc_assert (!bitmap_empty_p (aliases));
-
- 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++;
- }
-
- mark_sym_for_renaming (mpt);
- mark_sym_for_renaming (sym);
- set_memory_partition (sym, mpt);
- }
-
- mp_p->num_vops--;
-
- /* If we have already grouped enough, stop. */
- if (mp_p->num_vops <= (long) MAX_ALIASED_VOPS)
- break;
- }
-
- if (mpt)
- mark_call_clobbered (mpt, ESCAPE_UNKNOWN);
- }
-}
-
-
-/* Rewrite the alias set for TAG to use the newly created partitions.
- If TAG is NULL, rewrite the set of call-clobbered variables.
- NEW_ALIASES is a scratch bitmap to build the new set of aliases for
- TAG. */
-
-static void
-rewrite_alias_set_for (tree tag, bitmap new_aliases)
-{
- bitmap_iterator bi;
- unsigned i;
- tree mpt, sym;
-
- if (tag == NULL_TREE)
- {
- /* 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;
- }
- else
- {
- /* Create a new alias set for TAG with the new partitions. */
-
- EXECUTE_IF_SET_IN_BITMAP (MTAG_ALIASES (tag), 0, i, bi)
- {
- 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));
- }
-
- /* Rebuild the may-alias array for TAG. */
- bitmap_copy (MTAG_ALIASES (tag), new_aliases);
- }
-}
-
-
-/* Compute memory partitions.
-
- The partitioning is straightforward:
-
- 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. */
-
-static void
-compute_memory_partitions (void)
-{
- referenced_var_iterator rvi;
- tree var;
- unsigned i;
- struct mp_info_def mp;
- mp_info_t mp_p;
- VEC(mp_info_t,heap) *mp_info;
- long max_num_vops = 0;
- bitmap new_aliases;
-
- timevar_push (TV_MEMORY_PARTITIONING);
-
- mp_info = NULL;
- max_num_vops = 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);
- }
-
- /* 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;
-
- /* 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));
-
- /* No point grouping singleton alias sets. */
- if (mp.num_vops <= 1)
- continue;
-
- mp_p = xcalloc (1, sizeof (*mp_p));
- *mp_p = mp;
- VEC_safe_push (mp_info_t, heap, mp_info, mp_p);
-
- if (mp.num_vops > max_num_vops)
- max_num_vops = mp.num_vops;
- }
-
- if (dump_file)
- {
- fprintf (dump_file, "\n%s: Maximum number of VOPS needed per statement: "
- "%ld\n", get_name (current_function_decl), max_num_vops);
- }
-
- /* 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_mp_info (mp_info);
-
- if (dump_file)
- {
- fprintf (dump_file, "\nVOPS generated by pointer dereferences "
- "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++)
- {
- /* Stop processing if we are already below the threshold. */
- if (mp_p->num_vops <= (long) MAX_ALIASED_VOPS)
- break;
-
- create_partition_for (mp_p);
- }
-
- /* 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++)
- {
- rewrite_alias_set_for (mp_p->var, new_aliases);
- bitmap_clear (new_aliases);
- }
-
- BITMAP_FREE (new_aliases);
-
- if (dump_file)
- {
- fprintf (dump_file, "\nVOPS generated by pointer dereferences "
- "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);
-}
-
-/* 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. */
-
-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);
-}
-
-
-/* Compute may-alias information for every variable referenced in function
- FNDECL.
-
- Alias analysis proceeds in 3 main phases:
-
- 1- Points-to and escape analysis.
-
- This phase walks the use-def chains in the SSA web looking for three
- things:
-
- * Assignments of the form P_i = &VAR
- * Assignments of the form P_i = malloc()
- * Pointers and ADDR_EXPR that escape the current function.
-
- The concept of 'escaping' is the same one used in the Java world. When
- a pointer or an ADDR_EXPR escapes, it means that it has been exposed
- outside of the current function. So, assignment to global variables,
- function arguments and returning a pointer are all escape sites, as are
- conversions between pointers and integers.
-
- This is where we are currently limited. Since not everything is renamed
- into SSA, we lose track of escape properties when a pointer is stashed
- inside a field in a structure, for instance. In those cases, we are
- assuming that the pointer does escape.
-
- We use escape analysis to determine whether a variable is
- call-clobbered. Simply put, if an ADDR_EXPR escapes, then the variable
- is call-clobbered. If a pointer P_i escapes, then all the variables
- pointed-to by P_i (and its memory tag) also escape.
-
- 2- Compute flow-sensitive aliases
-
- We have two classes of memory tags. Memory tags associated with the
- pointed-to data type of the pointers in the program. These tags are
- called "symbol memory tag" (SMT). The other class are those associated
- with SSA_NAMEs, called "name memory tag" (NMT). The basic idea is that
- when adding operands for an INDIRECT_REF *P_i, we will first check
- whether P_i has a name tag, if it does we use it, because that will have
- more precise aliasing information. Otherwise, we use the standard symbol
- tag.
-
- In this phase, we go through all the pointers we found in points-to
- analysis and create alias sets for the name memory tags associated with
- each pointer P_i. If P_i escapes, we mark call-clobbered the variables
- it points to and its tag.
-
-
- 3- Compute flow-insensitive aliases
-
- This pass will compare the alias set of every symbol memory tag and
- every addressable variable found in the program. Given a symbol
- memory tag SMT and an addressable variable V. If the alias sets of
- SMT and V conflict (as computed by may_alias_p), then V is marked
- as an alias tag and added to the alias set of SMT.
-
- For instance, consider the following function:
-
- foo (int i)
- {
- int *p, a, b;
-
- if (i > 10)
- p = &a;
- else
- p = &b;
-
- *p = 3;
- a = b + 2;
- return *p;
- }
-
- After aliasing analysis has finished, the symbol memory tag for pointer
- 'p' will have two aliases, namely variables 'a' and 'b'. Every time
- pointer 'p' is dereferenced, we want to mark the operation as a
- potential reference to 'a' and 'b'.
-
- foo (int i)
- {
- int *p, a, b;
-
- if (i_2 > 10)
- p_4 = &a;
- else
- p_6 = &b;
- # p_1 = PHI <p_4(1), p_6(2)>;
-
- # a_7 = VDEF <a_3>;
- # b_8 = VDEF <b_5>;
- *p_1 = 3;
-
- # a_9 = VDEF <a_7>
- # VUSE <b_8>
- a_9 = b_8 + 2;
-
- # VUSE <a_9>;
- # VUSE <b_8>;
- return *p_1;
- }
-
- In certain cases, the list of may aliases for a pointer may grow too
- large. This may cause an explosion in the number of virtual operands
- inserted in the code. Resulting in increased memory consumption and
- 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. */
-
-static unsigned int
-compute_may_aliases (void)
-{
- struct alias_info *ai;
-
- memset (&alias_stats, 0, sizeof (alias_stats));
-
- /* Initialize aliasing information. */
- ai = init_alias_info ();
-
- /* For each pointer P_i, determine the sets of variables that P_i may
- point-to. For every addressable variable V, determine whether the
- address of V escapes the current function, making V call-clobbered
- (i.e., whether &V is stored in a global variable or if its passed as a
- function call argument). */
- compute_points_to_sets (ai);
-
- /* Collect all pointers and addressable variables, compute alias sets,
- create memory tags for pointers and promote variables whose address is
- not needed anymore. */
- setup_pointers_and_addressables (ai);
-
- /* Compute type-based flow-insensitive aliasing for all the type
- memory tags. */
- compute_flow_insensitive_aliasing (ai);
-
- /* Compute flow-sensitive, points-to based aliasing for all the name
- memory tags. */
- compute_flow_sensitive_aliasing (ai);
-
- /* Compute call clobbering information. */
- compute_call_clobbered (ai);
-
- /* If the program makes no reference to global variables, but it
- 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);
-
- /* If the program contains ref-all pointers, finalize may-alias information
- for them. This pass needs to be run after call-clobbering information
- has been computed. */
- if (ai->ref_all_symbol_mem_tag)
- finalize_ref_all_pointers (ai);
-
- /* Compute memory partitions for every memory variable. */
- compute_memory_partitions ();
-
- /* Debugging dumps. */
- if (dump_file)
- {
- dump_referenced_vars (dump_file);
- if (dump_flags & TDF_STATS)
- dump_alias_stats (dump_file);
- dump_points_to_info (dump_file);
- dump_alias_info (dump_file);
- }
-
- /* Set up is_aliased flags. */
- compute_is_aliased ();
-
- /* 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));
- }
- }
- }
- 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
-{
- tree ptr;
- unsigned count;
-};
-
-
-/* Helper for count_uses_and_derefs. Called by walk_tree to look for
- (ALIGN/MISALIGNED_)INDIRECT_REF nodes for the pointer passed in DATA. */
-
-static tree
-count_ptr_derefs (tree *tp, int *walk_subtrees, void *data)
-{
- struct count_ptr_d *count_p = (struct count_ptr_d *) data;
-
- /* Do not walk inside ADDR_EXPR nodes. In the expression &ptr->fld,
- pointer 'ptr' is *not* dereferenced, it is simply used to compute
- the address of 'fld' as 'ptr + offsetof(fld)'. */
- if (TREE_CODE (*tp) == ADDR_EXPR)
- {
- *walk_subtrees = 0;
- return NULL_TREE;
- }
-
- if (INDIRECT_REF_P (*tp) && TREE_OPERAND (*tp, 0) == count_p->ptr)
- count_p->count++;
-
- return NULL_TREE;
-}
-
-
-/* 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. */
-
-void
-count_uses_and_derefs (tree ptr, tree stmt, unsigned *num_uses_p,
- unsigned *num_derefs_p, bool *is_store)
-{
- ssa_op_iter i;
- tree use;
-
- *num_uses_p = 0;
- *num_derefs_p = 0;
- *is_store = false;
-
- /* Find out the total number of uses of PTR in STMT. */
- FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
- if (use == ptr)
- (*num_uses_p)++;
-
- /* Now count the number of indirect references to PTR. This is
- truly awful, but we don't have much choice. There are no parent
- pointers inside INDIRECT_REFs, so an expression like
- '*x_1 = foo (x_1, *x_1)' needs to be traversed piece by piece to
- find all the indirect and direct uses of x_1 inside. The only
- shortcut we can take is the fact that GIMPLE only allows
- INDIRECT_REFs inside the expressions below. */
- if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
- || (TREE_CODE (stmt) == RETURN_EXPR
- && TREE_CODE (TREE_OPERAND (stmt, 0)) == GIMPLE_MODIFY_STMT)
- || TREE_CODE (stmt) == ASM_EXPR
- || TREE_CODE (stmt) == CALL_EXPR)
- {
- tree lhs, rhs;
-
- if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
- {
- lhs = GIMPLE_STMT_OPERAND (stmt, 0);
- rhs = GIMPLE_STMT_OPERAND (stmt, 1);
- }
- else if (TREE_CODE (stmt) == RETURN_EXPR)
- {
- tree e = TREE_OPERAND (stmt, 0);
- lhs = GIMPLE_STMT_OPERAND (e, 0);
- rhs = GIMPLE_STMT_OPERAND (e, 1);
- }
- else if (TREE_CODE (stmt) == ASM_EXPR)
- {
- lhs = ASM_OUTPUTS (stmt);
- rhs = ASM_INPUTS (stmt);
- }
- else
- {
- lhs = NULL_TREE;
- rhs = stmt;
- }
-
- 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;
- }
-
- 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;
- }
- }
-
- gcc_assert (*num_uses_p >= *num_derefs_p);
-}
-
-/* Initialize the data structures used for alias analysis. */
-
-static struct alias_info *
-init_alias_info (void)
-{
- struct alias_info *ai;
- referenced_var_iterator rvi;
- tree var;
-
- ai = XCNEW (struct alias_info);
- ai->ssa_names_visited = sbitmap_alloc (num_ssa_names);
- sbitmap_zero (ai->ssa_names_visited);
- ai->processed_ptrs = VEC_alloc (tree, heap, 50);
- ai->written_vars = pointer_set_create ();
- ai->dereferenced_ptrs_store = pointer_set_create ();
- ai->dereferenced_ptrs_load = pointer_set_create ();
-
- /* 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);
- }
- }
- }
- else
- {
- /* If this is the first time we compute aliasing information,
- every non-register symbol will need to be put into SSA form
- (the initial SSA form only operates on GIMPLE registers). */
- FOR_EACH_REFERENCED_VAR (var, rvi)
- if (!is_gimple_reg (var))
- mark_sym_for_renaming (var);
- }
-
- /* Next time, we will need to reset alias information. */
- cfun->gimple_df->aliases_computed_p = true;
- bitmap_obstack_initialize (&alias_bitmap_obstack);
-
- return ai;
-}
-
-
-/* Deallocate memory used by alias analysis. */
-
-static void
-delete_alias_info (struct alias_info *ai)
-{
- size_t i;
-
- sbitmap_free (ai->ssa_names_visited);
-
- VEC_free (tree, heap, ai->processed_ptrs);
-
- for (i = 0; i < ai->num_addressable_vars; i++)
- free (ai->addressable_vars[i]);
- free (ai->addressable_vars);
-
- for (i = 0; i < ai->num_pointers; i++)
- free (ai->pointers[i]);
- free (ai->pointers);
-
- pointer_set_destroy (ai->written_vars);
- pointer_set_destroy (ai->dereferenced_ptrs_store);
- pointer_set_destroy (ai->dereferenced_ptrs_load);
- free (ai);
-
- 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)
-{
- const struct ptr_info_def *n1 = (const struct ptr_info_def *) p1;
- const struct ptr_info_def *n2 = (const struct ptr_info_def *) p2;
- return bitmap_equal_p (n1->pt_vars, n2->pt_vars);
-}
-
-static hashval_t
-ptr_info_hash (const void *p)
-{
- const struct ptr_info_def *n = (const struct ptr_info_def *) p;
- 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
- the result of a call to malloc (which means that P cannot point to
- anything else nor alias any other variable).
-
- If two pointers P and Q point to the same set of variables, they
- are assigned the same name tag. */
-
-static void
-create_name_tags (void)
-{
- size_t i;
- VEC (tree, heap) *with_ptvars = NULL;
- tree ptr;
- htab_t ptr_hash;
-
- /* Collect the list of pointers with a non-empty points to set. */
- for (i = 1; i < num_ssa_names; i++)
- {
- tree ptr = ssa_name (i);
- struct ptr_info_def *pi;
-
- if (!ptr
- || !POINTER_TYPE_P (TREE_TYPE (ptr))
- || !SSA_NAME_PTR_INFO (ptr))
- continue;
-
- pi = SSA_NAME_PTR_INFO (ptr);
-
- if (pi->pt_anything || !pi->is_dereferenced)
- {
- /* No name tags for pointers that have not been
- dereferenced or point to an arbitrary location. */
- pi->name_mem_tag = NULL_TREE;
- continue;
- }
-
- /* Set pt_anything on the pointers without pt_vars filled in so
- that they are assigned a symbol tag. */
- if (pi->pt_vars && !bitmap_empty_p (pi->pt_vars))
- VEC_safe_push (tree, heap, with_ptvars, ptr);
- else
- set_pt_anything (ptr);
- }
-
- /* If we didn't find any pointers with pt_vars set, we're done. */
- if (!with_ptvars)
- 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. */
- for (i = 0; VEC_iterate (tree, with_ptvars, i, ptr); i++)
- {
- struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
- tree old_name_tag = pi->name_mem_tag;
- struct ptr_info_def **slot;
-
- /* If PTR points to a set of variables, check if we don't
- have another pointer Q with the same points-to set before
- creating a tag. If so, use Q's tag instead of creating a
- new one.
-
- This is important for not creating unnecessary symbols
- and also for copy propagation. If we ever need to
- propagate PTR into Q or vice-versa, we would run into
- 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)
- pi->name_mem_tag = get_nmt_for (ptr);
- }
-
- /* If the new name tag computed for PTR is different than
- the old name tag that it used to have, then the old tag
- needs to be removed from the IL, so we mark it for
- renaming. */
- if (old_name_tag && old_name_tag != pi->name_mem_tag)
- mark_sym_for_renaming (old_name_tag);
-
- TREE_THIS_VOLATILE (pi->name_mem_tag)
- |= TREE_THIS_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 */
-
-static void
-union_alias_set_into (tree tag, bitmap set)
-{
- bitmap ma = MTAG_ALIASES (tag);
-
- if (bitmap_empty_p (set))
- return;
-
- if (!ma)
- ma = MTAG_ALIASES (tag) = BITMAP_ALLOC (&alias_bitmap_obstack);
- bitmap_ior_into (ma, set);
-}
-
-
-/* For every pointer P_i in AI->PROCESSED_PTRS, create may-alias sets for
- the name memory tag (NMT) associated with P_i. If P_i escapes, then its
- name tag and the variables it points-to are call-clobbered. Finally, if
- P_i escapes and we could not determine where it points to, then all the
- variables in the same alias set as *P_i are marked call-clobbered. This
- is necessary because we must assume that P_i may take the address of any
- variable in the same alias set. */
-
-static void
-compute_flow_sensitive_aliasing (struct alias_info *ai)
-{
- size_t i;
- tree ptr;
-
- set_used_smts ();
-
- for (i = 0; VEC_iterate (tree, ai->processed_ptrs, i, ptr); i++)
- {
- if (!find_what_p_points_to (ptr))
- set_pt_anything (ptr);
- }
-
- create_name_tags ();
-
- for (i = 0; VEC_iterate (tree, ai->processed_ptrs, i, ptr); i++)
- {
- struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
- tree tag = symbol_mem_tag (SSA_NAME_VAR (ptr));
-
- /* Set up aliasing information for PTR's name memory tag (if it has
- one). Note that only pointers that have been dereferenced will
- have a name memory tag. */
- if (pi->name_mem_tag && pi->pt_vars)
- {
- if (!bitmap_empty_p (pi->pt_vars))
- {
- union_alias_set_into (pi->name_mem_tag, pi->pt_vars);
- union_alias_set_into (tag, pi->pt_vars);
- bitmap_clear_bit (MTAG_ALIASES (tag), DECL_UID (tag));
-
- /* It may be the case that this the tag uid was the only
- bit we had set in the aliases list, and in this case,
- we don't want to keep an empty bitmap, as this
- asserts in tree-ssa-operands.c . */
- if (bitmap_empty_p (MTAG_ALIASES (tag)))
- BITMAP_FREE (MTAG_ALIASES (tag));
- }
- }
- }
-}
-
-
-/* Return TRUE if at least one symbol in TAG2's alias set is also
- present in TAG1's alias set. */
-
-static bool
-have_common_aliases_p (bitmap tag1aliases, bitmap tag2aliases)
-{
-
- /* This is the old behavior of have_common_aliases_p, which is to
- return false if both sets are empty, or one set is and the other
- isn't. */
- if ((tag1aliases == NULL && tag2aliases != NULL)
- || (tag2aliases == NULL && tag1aliases != NULL)
- || (tag1aliases == NULL && tag2aliases == NULL))
- return false;
-
- return bitmap_intersect_p (tag1aliases, tag2aliases);
-}
-
-/* Compute type-based alias sets. Traverse all the pointers and
- addressable variables found in setup_pointers_and_addressables.
-
- For every pointer P in AI->POINTERS and addressable variable V in
- AI->ADDRESSABLE_VARS, add V to the may-alias sets of P's symbol
- memory tag (SMT) if their alias sets conflict. V is then marked as
- an aliased symbol so that the operand scanner knows that statements
- containing V have aliased operands. */
-
-static void
-compute_flow_insensitive_aliasing (struct alias_info *ai)
-{
- size_t i;
-
- /* For every pointer P, determine which addressable variables may alias
- with P's symbol memory tag. */
- for (i = 0; i < ai->num_pointers; i++)
- {
- size_t j;
- struct alias_map_d *p_map = ai->pointers[i];
- tree tag = symbol_mem_tag (p_map->var);
- tree var;
-
- /* Call-clobbering information is not finalized yet at this point. */
- if (PTR_IS_REF_ALL (p_map->var))
- continue;
-
- for (j = 0; j < ai->num_addressable_vars; j++)
- {
- struct alias_map_d *v_map;
- var_ann_t v_ann;
- bool tag_stored_p, var_stored_p;
-
- v_map = ai->addressable_vars[j];
- var = v_map->var;
- v_ann = var_ann (var);
-
- /* Skip memory tags and variables that have never been
- written to. We also need to check if the variables are
- call-clobbered because they may be overwritten by
- function calls. */
- tag_stored_p = pointer_set_contains (ai->written_vars, tag)
- || is_call_clobbered (tag);
- var_stored_p = pointer_set_contains (ai->written_vars, var)
- || is_call_clobbered (var);
- if (!tag_stored_p && !var_stored_p)
- continue;
-
- if (may_alias_p (p_map->var, p_map->set, var, v_map->set, false))
- {
- /* We should never have a var with subvars here, because
- they shouldn't get into the set of addressable vars */
- gcc_assert (!var_can_have_subvars (var)
- || get_subvars_for_var (var) == NULL);
-
- /* Add VAR to TAG's may-aliases set. */
- add_may_alias (tag, var);
- }
- }
- }
-
- /* Since this analysis is based exclusively on symbols, it fails to
- handle cases where two pointers P and Q have different memory
- tags with conflicting alias set numbers but no aliased symbols in
- common.
-
- For example, suppose that we have two memory tags SMT.1 and SMT.2
- such that
-
- may-aliases (SMT.1) = { a }
- may-aliases (SMT.2) = { b }
-
- and the alias set number of SMT.1 conflicts with that of SMT.2.
- Since they don't have symbols in common, loads and stores from
- SMT.1 and SMT.2 will seem independent of each other, which will
- lead to the optimizers making invalid transformations (see
- testsuite/gcc.c-torture/execute/pr15262-[12].c).
-
- To avoid this problem, we do a final traversal of AI->POINTERS
- looking for pairs of pointers that have no aliased symbols in
- common and yet have conflicting alias set numbers. */
- for (i = 0; i < ai->num_pointers; i++)
- {
- size_t j;
- struct alias_map_d *p_map1 = ai->pointers[i];
- tree tag1 = symbol_mem_tag (p_map1->var);
- bitmap may_aliases1 = MTAG_ALIASES (tag1);
-
- if (PTR_IS_REF_ALL (p_map1->var))
- continue;
-
- for (j = i + 1; j < ai->num_pointers; j++)
- {
- struct alias_map_d *p_map2 = ai->pointers[j];
- tree tag2 = symbol_mem_tag (p_map2->var);
- bitmap may_aliases2 = may_aliases (tag2);
-
- if (PTR_IS_REF_ALL (p_map2->var))
- continue;
-
- /* If the pointers may not point to each other, do nothing. */
- if (!may_alias_p (p_map1->var, p_map1->set, tag2, p_map2->set, true))
- continue;
-
- /* The two pointers may alias each other. If they already have
- symbols in common, do nothing. */
- if (have_common_aliases_p (may_aliases1, may_aliases2))
- continue;
+/* Broad overview of how alias analysis on gimple works:
- if (may_aliases2 && !bitmap_empty_p (may_aliases2))
- {
- union_alias_set_into (tag1, may_aliases2);
- }
- else
- {
- /* Since TAG2 does not have any aliases of its own, add
- TAG2 itself to the alias set of TAG1. */
- add_may_alias (tag1, tag2);
- }
- }
-
- }
-}
-
-
-/* Finalize may-alias information for ref-all pointers. Traverse all
- the addressable variables found in setup_pointers_and_addressables.
-
- If flow-sensitive alias analysis has attached a name memory tag to
- a ref-all pointer, we will use it for the dereferences because that
- will have more precise aliasing information. But if there is no
- name tag, we will use a special symbol tag that aliases all the
- call-clobbered addressable variables. */
-
-static void
-finalize_ref_all_pointers (struct alias_info *ai)
-{
- size_t i;
-
- /* First add the real call-clobbered variables. */
- for (i = 0; i < ai->num_addressable_vars; i++)
- {
- tree var = ai->addressable_vars[i]->var;
- if (is_call_clobbered (var))
- add_may_alias (ai->ref_all_symbol_mem_tag, var);
- }
-
- /* Then add the call-clobbered pointer memory tags. See
- compute_flow_insensitive_aliasing for the rationale. */
- for (i = 0; i < ai->num_pointers; i++)
- {
- tree ptr = ai->pointers[i]->var, tag;
- if (PTR_IS_REF_ALL (ptr))
- continue;
- tag = symbol_mem_tag (ptr);
- if (is_call_clobbered (tag))
- add_may_alias (ai->ref_all_symbol_mem_tag, tag);
- }
-
-}
+ Statements clobbering or using memory are linked through the
+ virtual operand factored use-def chain. The virtual operand
+ is unique per function, its symbol is accessible via gimple_vop (cfun).
+ Virtual operands are used for efficiently walking memory statements
+ in the gimple IL and are useful for things like value-numbering as
+ a generation count for memory references.
+ SSA_NAME pointers may have associated points-to information
+ accessible via the SSA_NAME_PTR_INFO macro. Flow-insensitive
+ points-to information is (re-)computed by the TODO_rebuild_alias
+ pass manager todo. Points-to information is also used for more
+ precise tracking of call-clobbered and call-used variables and
+ related disambiguations.
-/* Create a new alias set entry for VAR in AI->ADDRESSABLE_VARS. */
+ This file contains functions for disambiguating memory references,
+ the so called alias-oracle and tools for walking of the gimple IL.
-static void
-create_alias_map_for (tree var, struct alias_info *ai)
-{
- struct alias_map_d *alias_map;
- alias_map = XCNEW (struct alias_map_d);
- alias_map->var = var;
- alias_map->set = get_alias_set (var);
- ai->addressable_vars[ai->num_addressable_vars++] = alias_map;
-}
+ The main alias-oracle entry-points are
+ bool stmt_may_clobber_ref_p (gimple, tree)
-/* Create memory tags for all the dereferenced pointers and build the
- ADDRESSABLE_VARS and POINTERS arrays used for building the may-alias
- sets. Based on the address escape and points-to information collected
- earlier, this pass will also clear the TREE_ADDRESSABLE flag from those
- variables whose address is not needed anymore. */
+ This function queries if a statement may invalidate (parts of)
+ the memory designated by the reference tree argument.
-static void
-setup_pointers_and_addressables (struct alias_info *ai)
-{
- size_t num_addressable_vars, num_pointers;
- referenced_var_iterator rvi;
- tree var;
- VEC (tree, heap) *varvec = NULL;
- safe_referenced_var_iterator srvi;
+ bool ref_maybe_used_by_stmt_p (gimple, tree)
- /* Size up the arrays ADDRESSABLE_VARS and POINTERS. */
- num_addressable_vars = num_pointers = 0;
-
- FOR_EACH_REFERENCED_VAR (var, rvi)
- {
- if (may_be_aliased (var))
- num_addressable_vars++;
+ This function queries if a statement may need (parts of) the
+ memory designated by the reference tree argument.
- if (POINTER_TYPE_P (TREE_TYPE (var)))
- {
- /* Since we don't keep track of volatile variables, assume that
- these pointers are used in indirect store operations. */
- if (TREE_THIS_VOLATILE (var))
- pointer_set_insert (ai->dereferenced_ptrs_store, var);
+ There are variants of these functions that only handle the call
+ part of a statement, call_may_clobber_ref_p and ref_maybe_used_by_call_p.
+ Note that these do not disambiguate against a possible call lhs.
- num_pointers++;
- }
- }
+ bool refs_may_alias_p (tree, tree)
- /* Create ADDRESSABLE_VARS and POINTERS. Note that these arrays are
- always going to be slightly bigger than we actually need them
- because some TREE_ADDRESSABLE variables will be marked
- non-addressable below and only pointers with unique symbol tags are
- going to be added to POINTERS. */
- ai->addressable_vars = XCNEWVEC (struct alias_map_d *, num_addressable_vars);
- ai->pointers = XCNEWVEC (struct alias_map_d *, num_pointers);
- ai->num_addressable_vars = 0;
- ai->num_pointers = 0;
-
- FOR_EACH_REFERENCED_VAR_SAFE (var, varvec, srvi)
- {
- subvar_t svars;
-
- /* Name memory tags already have flow-sensitive aliasing
- information, so they need not be processed by
- compute_flow_insensitive_aliasing. Similarly, symbol memory
- tags are already accounted for when we process their
- associated pointer.
-
- Structure fields, on the other hand, have to have some of this
- information processed for them, but it's pointless to mark them
- non-addressable (since they are fake variables anyway). */
- if (MTAG_P (var) && TREE_CODE (var) != STRUCT_FIELD_TAG)
- continue;
+ This function tries to disambiguate two reference trees.
- /* Remove the ADDRESSABLE flag from every addressable variable whose
- address is not needed anymore. This is caused by the propagation
- of ADDR_EXPR constants into INDIRECT_REF expressions and the
- removal of dead pointer assignments done by the early scalar
- cleanup passes. */
- if (TREE_ADDRESSABLE (var))
- {
- if (!bitmap_bit_p (gimple_addressable_vars (cfun), DECL_UID (var))
- && TREE_CODE (var) != RESULT_DECL
- && !is_global_var (var))
- {
- bool okay_to_mark = true;
+ bool ptr_deref_may_alias_global_p (tree)
- /* Since VAR is now a regular GIMPLE register, we will need
- to rename VAR into SSA afterwards. */
- mark_sym_for_renaming (var);
+ This function queries if dereferencing a pointer variable may
+ alias global memory.
- /* If VAR can have sub-variables, and any of its
- sub-variables has its address taken, then we cannot
- remove the addressable flag from VAR. */
- if (var_can_have_subvars (var)
- && (svars = get_subvars_for_var (var)))
- {
- subvar_t sv;
-
- for (sv = svars; sv; sv = sv->next)
- {
- if (bitmap_bit_p (gimple_addressable_vars (cfun),
- DECL_UID (sv->var)))
- okay_to_mark = false;
- mark_sym_for_renaming (sv->var);
- }
- }
+ More low-level disambiguators are available and documented in
+ this file. Low-level disambiguators dealing with points-to
+ information are in tree-ssa-structalias.c. */
- /* The address of VAR is not needed, remove the
- addressable bit, so that it can be optimized as a
- regular variable. */
- if (okay_to_mark)
- {
- /* The memory partition holding VAR will no longer
- contain VAR, and statements referencing it will need
- to be updated. */
- if (memory_partition (var))
- mark_sym_for_renaming (memory_partition (var));
- mark_non_addressable (var);
- }
- }
- }
+/* Query statistics for the different low-level disambiguators.
+ A high-level query may trigger multiple of them. */
- /* Global variables and addressable locals may be aliased. Create an
- entry in ADDRESSABLE_VARS for VAR. */
- if (may_be_aliased (var))
- {
- if (!var_can_have_subvars (var)
- || get_subvars_for_var (var) == NULL)
- create_alias_map_for (var, ai);
+static struct {
+ unsigned HOST_WIDE_INT refs_may_alias_p_may_alias;
+ unsigned HOST_WIDE_INT refs_may_alias_p_no_alias;
+ unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_may_alias;
+ unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_no_alias;
+ unsigned HOST_WIDE_INT call_may_clobber_ref_p_may_alias;
+ unsigned HOST_WIDE_INT call_may_clobber_ref_p_no_alias;
+} alias_stats;
- mark_sym_for_renaming (var);
- }
+void
+dump_alias_stats (FILE *s)
+{
+ fprintf (s, "\nAlias oracle query stats:\n");
+ fprintf (s, " refs_may_alias_p: "
+ HOST_WIDE_INT_PRINT_DEC" disambiguations, "
+ HOST_WIDE_INT_PRINT_DEC" queries\n",
+ alias_stats.refs_may_alias_p_no_alias,
+ alias_stats.refs_may_alias_p_no_alias
+ + alias_stats.refs_may_alias_p_may_alias);
+ fprintf (s, " ref_maybe_used_by_call_p: "
+ HOST_WIDE_INT_PRINT_DEC" disambiguations, "
+ HOST_WIDE_INT_PRINT_DEC" queries\n",
+ alias_stats.ref_maybe_used_by_call_p_no_alias,
+ alias_stats.refs_may_alias_p_no_alias
+ + alias_stats.ref_maybe_used_by_call_p_may_alias);
+ fprintf (s, " call_may_clobber_ref_p: "
+ HOST_WIDE_INT_PRINT_DEC" disambiguations, "
+ HOST_WIDE_INT_PRINT_DEC" queries\n",
+ alias_stats.call_may_clobber_ref_p_no_alias,
+ alias_stats.call_may_clobber_ref_p_no_alias
+ + alias_stats.call_may_clobber_ref_p_may_alias);
+}
+
+
+/* Return true, if dereferencing PTR may alias with a global variable. */
- /* Add pointer variables that have been dereferenced to the POINTERS
- array and create a symbol memory tag for them. */
- if (POINTER_TYPE_P (TREE_TYPE (var)))
- {
- if ((pointer_set_contains (ai->dereferenced_ptrs_store, var)
- || pointer_set_contains (ai->dereferenced_ptrs_load, var)))
- {
- tree tag, old_tag;
- var_ann_t t_ann;
-
- /* If pointer VAR still doesn't have a memory tag
- associated with it, create it now or re-use an
- existing one. */
- tag = get_smt_for (var, ai);
- t_ann = var_ann (tag);
-
- /* The symbol tag will need to be renamed into SSA
- afterwards. Note that we cannot do this inside
- get_smt_for because aliasing may run multiple times
- and we only create symbol tags the first time. */
- mark_sym_for_renaming (tag);
-
- /* Similarly, if pointer VAR used to have another type
- tag, we will need to process it in the renamer to
- remove the stale virtual operands. */
- old_tag = symbol_mem_tag (var);
- if (old_tag)
- mark_sym_for_renaming (old_tag);
-
- /* Associate the tag with pointer VAR. */
- set_symbol_mem_tag (var, tag);
-
- /* If pointer VAR has been used in a store operation,
- then its memory tag must be marked as written-to. */
- if (pointer_set_contains (ai->dereferenced_ptrs_store, var))
- pointer_set_insert (ai->written_vars, tag);
- }
- else
- {
- /* The pointer has not been dereferenced. If it had a
- symbol memory tag, remove it and mark the old tag for
- renaming to remove it out of the IL. */
- tree tag = symbol_mem_tag (var);
- if (tag)
- {
- mark_sym_for_renaming (tag);
- set_symbol_mem_tag (var, NULL_TREE);
- }
- }
- }
- }
+bool
+ptr_deref_may_alias_global_p (tree ptr)
+{
+ struct ptr_info_def *pi;
- VEC_free (tree, heap, varvec);
-}
+ /* If we end up with a pointer constant here that may point
+ to global memory. */
+ if (TREE_CODE (ptr) != SSA_NAME)
+ return true;
+ pi = SSA_NAME_PTR_INFO (ptr);
-/* Determine whether to use .GLOBAL_VAR to model call clobbering
- semantics. If the function makes no references to global
- variables and contains at least one call to a non-pure function,
- then we need to mark the side-effects of the call using .GLOBAL_VAR
- to represent all possible global memory referenced by the callee. */
+ /* If we do not have points-to information for this variable,
+ we have to punt. */
+ if (!pi)
+ return true;
-static void
-maybe_create_global_var (struct alias_info *ai)
-{
- /* No need to create it, if we have one already. */
- if (gimple_global_var (cfun) == NULL_TREE)
- {
- /* 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
- described in PR 20115:
-
- int X;
- int func_pure (void) { return X; }
- int func_non_pure (int a) { X += a; }
- int foo ()
- {
- int a = func_pure ();
- func_non_pure (a);
- a = func_pure ();
- return a;
- }
-
- Since foo() has no call-clobbered variables, there is
- no relationship between the calls to func_pure and
- func_non_pure. Since func_pure has no side-effects, value
- numbering optimizations elide the second call to func_pure.
- 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)
- create_global_var ();
- }
+ /* ??? This does not use TBAA to prune globals ptr may not access. */
+ return pt_solution_includes_global (&pi->pt);
}
-
-/* Return TRUE if pointer PTR may point to variable VAR.
-
- MEM_ALIAS_SET is the alias set for the memory location pointed-to by PTR
- This is needed because when checking for type conflicts we are
- interested in the alias set of the memory location pointed-to by
- PTR. The alias set of PTR itself is irrelevant.
-
- VAR_ALIAS_SET is the alias set for VAR. */
+/* Return true if dereferencing PTR may alias DECL.
+ The caller is responsible for applying TBAA to see if PTR
+ may access DECL at all. */
static bool
-may_alias_p (tree ptr, HOST_WIDE_INT mem_alias_set,
- tree var, HOST_WIDE_INT var_alias_set,
- bool alias_set_only)
+ptr_deref_may_alias_decl_p (tree ptr, tree decl)
{
- tree mem;
-
- alias_stats.alias_queries++;
- alias_stats.simple_queries++;
-
- /* By convention, a variable cannot alias itself. */
- mem = symbol_mem_tag (ptr);
- if (mem == var)
- {
- alias_stats.alias_noalias++;
- alias_stats.simple_resolved++;
- return false;
- }
-
- /* If -fargument-noalias-global is > 2, pointer arguments may
- not point to anything else. */
- if (flag_argument_noalias > 2 && TREE_CODE (ptr) == PARM_DECL)
- {
- alias_stats.alias_noalias++;
- alias_stats.simple_resolved++;
- return false;
- }
-
- /* If -fargument-noalias-global is > 1, pointer arguments may
- not point to global variables. */
- if (flag_argument_noalias > 1 && is_global_var (var)
- && TREE_CODE (ptr) == PARM_DECL)
- {
- alias_stats.alias_noalias++;
- alias_stats.simple_resolved++;
- return false;
- }
-
- /* If either MEM or VAR is a read-only global and the other one
- isn't, then PTR cannot point to VAR. */
- if ((unmodifiable_var_p (mem) && !unmodifiable_var_p (var))
- || (unmodifiable_var_p (var) && !unmodifiable_var_p (mem)))
- {
- alias_stats.alias_noalias++;
- alias_stats.simple_resolved++;
- return false;
- }
-
- gcc_assert (TREE_CODE (mem) == SYMBOL_MEMORY_TAG);
+ struct ptr_info_def *pi;
- alias_stats.tbaa_queries++;
+ gcc_assert ((TREE_CODE (ptr) == SSA_NAME
+ || TREE_CODE (ptr) == ADDR_EXPR
+ || TREE_CODE (ptr) == INTEGER_CST)
+ && (TREE_CODE (decl) == VAR_DECL
+ || TREE_CODE (decl) == PARM_DECL
+ || TREE_CODE (decl) == RESULT_DECL));
- /* If the alias sets don't conflict then MEM cannot alias VAR. */
- if (!alias_sets_conflict_p (mem_alias_set, var_alias_set))
- {
- alias_stats.alias_noalias++;
- alias_stats.tbaa_resolved++;
- return false;
- }
+ /* Non-aliased variables can not be pointed to. */
+ if (!may_be_aliased (decl))
+ 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)
- {
- 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))
- {
- /* 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;
- }
- }
+ /* ADDR_EXPR pointers either just offset another pointer or directly
+ specify the pointed-to set. */
+ if (TREE_CODE (ptr) == ADDR_EXPR)
+ {
+ tree base = get_base_address (TREE_OPERAND (ptr, 0));
+ if (base
+ && INDIRECT_REF_P (base))
+ ptr = TREE_OPERAND (base, 0);
+ else if (base
+ && SSA_VAR_P (base))
+ return operand_equal_p (base, decl, 0);
+ else if (base
+ && CONSTANT_CLASS_P (base))
+ return false;
+ else
+ return true;
}
- alias_stats.alias_mayalias++;
- return true;
-}
-
-
-/* Add ALIAS to the set of variables that may alias VAR. */
-
-static void
-add_may_alias (tree var, tree alias)
-{
-
- /* Don't allow self-referential aliases. */
- gcc_assert (var != alias);
-
- /* ALIAS must be addressable if it's being added to an alias set. */
-#if 1
- TREE_ADDRESSABLE (alias) = 1;
-#else
- gcc_assert (may_be_aliased (alias));
-#endif
-
- /* VAR must be a symbol or a name tag. */
- gcc_assert (TREE_CODE (var) == SYMBOL_MEMORY_TAG
- || TREE_CODE (var) == NAME_MEMORY_TAG);
-
- if (MTAG_ALIASES (var) == NULL)
- MTAG_ALIASES (var) = BITMAP_ALLOC (&alias_bitmap_obstack);
-
- bitmap_set_bit (MTAG_ALIASES (var), DECL_UID (alias));
-}
-
-
-/* Mark pointer PTR as pointing to an arbitrary memory location. */
+ /* We can end up with dereferencing constant pointers.
+ Just bail out in this case. */
+ if (TREE_CODE (ptr) == INTEGER_CST)
+ return true;
-static void
-set_pt_anything (tree ptr)
-{
- struct ptr_info_def *pi = get_ptr_info (ptr);
+ /* If we do not have useful points-to information for this pointer
+ we cannot disambiguate anything else. */
+ pi = SSA_NAME_PTR_INFO (ptr);
+ if (!pi)
+ return true;
- pi->pt_anything = 1;
- pi->pt_vars = NULL;
+ /* If the decl can be used as a restrict tag and we have a restrict
+ pointer and that pointers points-to set doesn't contain this decl
+ then they can't alias. */
+ if (DECL_RESTRICTED_P (decl)
+ && TYPE_RESTRICT (TREE_TYPE (ptr))
+ && pi->pt.vars_contains_restrict)
+ return bitmap_bit_p (pi->pt.vars, DECL_UID (decl));
- /* The pointer used to have a name tag, but we now found it pointing
- to an arbitrary location. The name tag needs to be renamed and
- disassociated from PTR. */
- if (pi->name_mem_tag)
- {
- mark_sym_for_renaming (pi->name_mem_tag);
- pi->name_mem_tag = NULL_TREE;
- }
+ return pt_solution_includes (&pi->pt, decl);
}
+/* Return true if dereferenced PTR1 and PTR2 may alias.
+ The caller is responsible for applying TBAA to see if accesses
+ through PTR1 and PTR2 may conflict at all. */
-/* Return true if STMT is an "escape" site from the current function. Escape
- sites those statements which might expose the address of a variable
- outside the current function. STMT is an escape site iff:
-
- 1- STMT is a function call, or
- 2- STMT is an __asm__ expression, or
- 3- STMT is an assignment to a non-local variable, or
- 4- STMT is a return statement.
-
- Return the type of escape site found, if we found one, or NO_ESCAPE
- if none. */
-
-enum escape_type
-is_escape_site (tree stmt)
-{
- tree call = get_call_expr_in (stmt);
- if (call != NULL_TREE)
- {
- if (!TREE_SIDE_EFFECTS (call))
- return ESCAPE_TO_PURE_CONST;
-
- return ESCAPE_TO_CALL;
+static bool
+ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
+{
+ struct ptr_info_def *pi1, *pi2;
+
+ gcc_assert ((TREE_CODE (ptr1) == SSA_NAME
+ || TREE_CODE (ptr1) == ADDR_EXPR
+ || TREE_CODE (ptr1) == INTEGER_CST)
+ && (TREE_CODE (ptr2) == SSA_NAME
+ || TREE_CODE (ptr2) == ADDR_EXPR
+ || TREE_CODE (ptr2) == INTEGER_CST));
+
+ /* ADDR_EXPR pointers either just offset another pointer or directly
+ specify the pointed-to set. */
+ if (TREE_CODE (ptr1) == ADDR_EXPR)
+ {
+ tree base = get_base_address (TREE_OPERAND (ptr1, 0));
+ if (base
+ && INDIRECT_REF_P (base))
+ ptr1 = TREE_OPERAND (base, 0);
+ else if (base
+ && SSA_VAR_P (base))
+ return ptr_deref_may_alias_decl_p (ptr2, base);
+ else
+ return true;
}
- else if (TREE_CODE (stmt) == ASM_EXPR)
- return ESCAPE_TO_ASM;
- else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
+ if (TREE_CODE (ptr2) == ADDR_EXPR)
{
- tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
-
- /* Get to the base of _REF nodes. */
- if (TREE_CODE (lhs) != SSA_NAME)
- lhs = get_base_address (lhs);
-
- /* If we couldn't recognize the LHS of the assignment, assume that it
- is a non-local store. */
- if (lhs == NULL_TREE)
- return ESCAPE_UNKNOWN;
-
- if (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == NOP_EXPR
- || TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == CONVERT_EXPR
- || TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == VIEW_CONVERT_EXPR)
- {
- tree from
- = TREE_TYPE (TREE_OPERAND (GIMPLE_STMT_OPERAND (stmt, 1), 0));
- tree to = TREE_TYPE (GIMPLE_STMT_OPERAND (stmt, 1));
-
- /* If the RHS is a conversion between a pointer and an integer, the
- pointer escapes since we can't track the integer. */
- if (POINTER_TYPE_P (from) && !POINTER_TYPE_P (to))
- return ESCAPE_BAD_CAST;
-
- /* Same if the RHS is a conversion between a regular pointer and a
- ref-all pointer since we can't track the SMT of the former. */
- if (POINTER_TYPE_P (from) && !TYPE_REF_CAN_ALIAS_ALL (from)
- && POINTER_TYPE_P (to) && TYPE_REF_CAN_ALIAS_ALL (to))
- return ESCAPE_BAD_CAST;
- }
-
- /* If the LHS is an SSA name, it can't possibly represent a non-local
- memory store. */
- if (TREE_CODE (lhs) == SSA_NAME)
- return NO_ESCAPE;
-
- /* FIXME: LHS is not an SSA_NAME. Even if it's an assignment to a
- local variables we cannot be sure if it will escape, because we
- don't have information about objects not in SSA form. Need to
- implement something along the lines of
-
- J.-D. Choi, M. Gupta, M. J. Serrano, V. C. Sreedhar, and S. P.
- Midkiff, ``Escape analysis for java,'' in Proceedings of the
- Conference on Object-Oriented Programming Systems, Languages, and
- Applications (OOPSLA), pp. 1-19, 1999. */
- return ESCAPE_STORED_IN_GLOBAL;
+ tree base = get_base_address (TREE_OPERAND (ptr2, 0));
+ if (base
+ && INDIRECT_REF_P (base))
+ ptr2 = TREE_OPERAND (base, 0);
+ else if (base
+ && SSA_VAR_P (base))
+ return ptr_deref_may_alias_decl_p (ptr1, base);
+ else
+ return true;
}
- else if (TREE_CODE (stmt) == RETURN_EXPR)
- return ESCAPE_TO_RETURN;
-
- return NO_ESCAPE;
-}
-
-/* Create a new memory tag of type TYPE.
- Does NOT push it into the current binding. */
-
-tree
-create_tag_raw (enum tree_code code, tree type, const char *prefix)
-{
- tree tmp_var;
-
- tmp_var = build_decl (code, create_tmp_var_name (prefix), type);
-
- /* Make the variable writable. */
- TREE_READONLY (tmp_var) = 0;
-
- /* It doesn't start out global. */
- MTAG_GLOBAL (tmp_var) = 0;
- TREE_STATIC (tmp_var) = 0;
- TREE_USED (tmp_var) = 1;
-
- return tmp_var;
-}
-
-/* Create a new memory tag of type TYPE. If IS_TYPE_TAG is true, the tag
- is considered to represent all the pointers whose pointed-to types are
- in the same alias set class. Otherwise, the tag represents a single
- SSA_NAME pointer variable. */
-
-static tree
-create_memory_tag (tree type, bool is_type_tag)
-{
- tree tag = create_tag_raw (is_type_tag ? SYMBOL_MEMORY_TAG : NAME_MEMORY_TAG,
- type, (is_type_tag) ? "SMT" : "NMT");
-
- /* By default, memory tags are local variables. Alias analysis will
- determine whether they should be considered globals. */
- DECL_CONTEXT (tag) = current_function_decl;
-
- /* Memory tags are by definition addressable. */
- TREE_ADDRESSABLE (tag) = 1;
-
- set_symbol_mem_tag (tag, NULL_TREE);
- /* Add the tag to the symbol table. */
- add_referenced_var (tag);
-
- return tag;
-}
+ /* We can end up with dereferencing constant pointers.
+ Just bail out in this case. */
+ if (TREE_CODE (ptr1) == INTEGER_CST
+ || TREE_CODE (ptr2) == INTEGER_CST)
+ return true;
+ /* We may end up with two empty points-to solutions for two same pointers.
+ In this case we still want to say both pointers alias, so shortcut
+ that here. */
+ if (ptr1 == ptr2)
+ return true;
-/* Create a name memory tag to represent a specific SSA_NAME pointer P_i.
- This is used if P_i has been found to point to a specific set of
- variables or to a non-aliased memory location like the address returned
- by malloc functions. */
+ /* If we do not have useful points-to information for either pointer
+ we cannot disambiguate anything else. */
+ pi1 = SSA_NAME_PTR_INFO (ptr1);
+ pi2 = SSA_NAME_PTR_INFO (ptr2);
+ if (!pi1 || !pi2)
+ return true;
-static tree
-get_nmt_for (tree ptr)
-{
- struct ptr_info_def *pi = get_ptr_info (ptr);
- tree tag = pi->name_mem_tag;
+ /* If both pointers are restrict-qualified try to disambiguate
+ with restrict information. */
+ if (TYPE_RESTRICT (TREE_TYPE (ptr1))
+ && TYPE_RESTRICT (TREE_TYPE (ptr2))
+ && !pt_solutions_same_restrict_base (&pi1->pt, &pi2->pt))
+ return false;
- if (tag == NULL_TREE)
- tag = create_memory_tag (TREE_TYPE (TREE_TYPE (ptr)), false);
- return tag;
+ /* ??? This does not use TBAA to prune decls from the intersection
+ that not both pointers may access. */
+ return pt_solutions_intersect (&pi1->pt, &pi2->pt);
}
+/* Return true if dereferencing PTR may alias *REF.
+ The caller is responsible for applying TBAA to see if PTR
+ may access *REF at all. */
-/* Return the symbol memory tag associated to pointer PTR. A memory
- tag is an artificial variable that represents the memory location
- pointed-to by PTR. It is used to model the effects of pointer
- de-references on addressable variables.
-
- AI points to the data gathered during alias analysis. This
- function populates the array AI->POINTERS. */
-
-static tree
-get_smt_for (tree ptr, struct alias_info *ai)
+static bool
+ptr_deref_may_alias_ref_p_1 (tree ptr, ao_ref *ref)
{
- size_t i;
- tree tag;
- tree tag_type = TREE_TYPE (TREE_TYPE (ptr));
- HOST_WIDE_INT 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))
- {
- if (!ai->ref_all_symbol_mem_tag)
- ai->ref_all_symbol_mem_tag = create_memory_tag (void_type_node, true);
- return ai->ref_all_symbol_mem_tag;
- }
-
- /* To avoid creating unnecessary memory tags, only create one memory tag
- per alias set class. Note that it may be tempting to group
- memory tags based on conflicting alias sets instead of
- equivalence. That would be wrong because alias sets are not
- necessarily transitive (as demonstrated by the libstdc++ test
- 23_containers/vector/cons/4.cc). Given three alias sets A, B, C
- such that conflicts (A, B) == true and conflicts (A, C) == true,
- it does not necessarily follow that conflicts (B, C) == true. */
- for (i = 0, tag = NULL_TREE; i < ai->num_pointers; i++)
- {
- struct alias_map_d *curr = ai->pointers[i];
- tree curr_tag = symbol_mem_tag (curr->var);
- if (tag_set == curr->set)
- {
- tag = curr_tag;
- break;
- }
- }
-
- /* If VAR cannot alias with any of the existing memory tags, create a new
- tag for PTR and add it to the POINTERS array. */
- if (tag == NULL_TREE)
- {
- struct alias_map_d *alias_map;
-
- /* If PTR did not have a symbol tag already, create a new SMT.*
- artificial variable representing the memory location
- pointed-to by PTR. */
- tag = symbol_mem_tag (ptr);
- if (tag == NULL_TREE)
- tag = create_memory_tag (tag_type, true);
-
- /* Add PTR to the POINTERS array. Note that we are not interested in
- PTR's alias set. Instead, we cache the alias set for the memory that
- PTR points to. */
- alias_map = XCNEW (struct alias_map_d);
- alias_map->var = ptr;
- alias_map->set = tag_set;
- ai->pointers[ai->num_pointers++] = alias_map;
- }
-
- /* If the pointed-to type is volatile, so is the tag. */
- TREE_THIS_VOLATILE (tag) |= TREE_THIS_VOLATILE (tag_type);
-
- /* Make sure that the symbol tag has the same alias set as the
- pointed-to type. */
- gcc_assert (tag_set == get_alias_set (tag));
-
- return tag;
-}
-
+ tree base = ao_ref_base (ref);
-/* Create GLOBAL_VAR, an artificial global variable to act as a
- representative of all the variables that may be clobbered by function
- calls. */
+ if (INDIRECT_REF_P (base))
+ return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0));
+ else if (SSA_VAR_P (base))
+ return ptr_deref_may_alias_decl_p (ptr, base);
-static void
-create_global_var (void)
-{
- tree global_var = build_decl (VAR_DECL, get_identifier (".GLOBAL_VAR"),
- void_type_node);
- DECL_ARTIFICIAL (global_var) = 1;
- TREE_READONLY (global_var) = 0;
- DECL_EXTERNAL (global_var) = 1;
- TREE_STATIC (global_var) = 1;
- TREE_USED (global_var) = 1;
- DECL_CONTEXT (global_var) = NULL_TREE;
- TREE_THIS_VOLATILE (global_var) = 0;
- TREE_ADDRESSABLE (global_var) = 0;
-
- create_var_ann (global_var);
- mark_call_clobbered (global_var, ESCAPE_UNKNOWN);
- add_referenced_var (global_var);
- mark_sym_for_renaming (global_var);
- cfun->gimple_df->global_var = global_var;
+ return true;
}
-/* Dump alias statistics on FILE. */
-
-static void
-dump_alias_stats (FILE *file)
-{
- const char *funcname
- = lang_hooks.decl_printable_name (current_function_decl, 2);
- fprintf (file, "\nAlias statistics for %s\n\n", funcname);
- fprintf (file, "Total alias queries:\t%u\n", alias_stats.alias_queries);
- fprintf (file, "Total alias mayalias results:\t%u\n",
- alias_stats.alias_mayalias);
- fprintf (file, "Total alias noalias results:\t%u\n",
- alias_stats.alias_noalias);
- fprintf (file, "Total simple queries:\t%u\n",
- alias_stats.simple_queries);
- fprintf (file, "Total simple resolved:\t%u\n",
- alias_stats.simple_resolved);
- fprintf (file, "Total TBAA queries:\t%u\n",
- alias_stats.tbaa_queries);
- fprintf (file, "Total TBAA resolved:\t%u\n",
- alias_stats.tbaa_resolved);
- fprintf (file, "Total non-addressable structure type queries:\t%u\n",
- alias_stats.structnoaddress_queries);
- fprintf (file, "Total non-addressable structure type resolved:\t%u\n",
- alias_stats.structnoaddress_resolved);
-}
-
-
/* Dump alias information on FILE. */
void
referenced_var_iterator rvi;
tree var;
- fprintf (file, "\nFlow-insensitive alias information for %s\n\n", funcname);
+ fprintf (file, "\n\nAlias information for %s\n\n", funcname);
fprintf (file, "Aliased symbols\n\n");
-
+
FOR_EACH_REFERENCED_VAR (var, rvi)
{
if (may_be_aliased (var))
dump_variable (file, var);
}
- fprintf (file, "\nDereferenced pointers\n\n");
-
- FOR_EACH_REFERENCED_VAR (var, rvi)
- if (symbol_mem_tag (var))
- dump_variable (file, var);
+ fprintf (file, "\nCall clobber information\n");
- fprintf (file, "\nSymbol memory tags\n\n");
-
- FOR_EACH_REFERENCED_VAR (var, rvi)
- {
- if (TREE_CODE (var) == SYMBOL_MEMORY_TAG)
- dump_variable (file, var);
- }
+ fprintf (file, "\nESCAPED");
+ dump_points_to_solution (file, &cfun->gimple_df->escaped);
+ fprintf (file, "\nCALLUSED");
+ dump_points_to_solution (file, &cfun->gimple_df->callused);
- fprintf (file, "\n\nFlow-sensitive alias information for %s\n\n", funcname);
+ fprintf (file, "\n\nFlow-insensitive points-to information\n\n");
- fprintf (file, "SSA_NAME pointers\n\n");
for (i = 1; i < num_ssa_names; i++)
{
tree ptr = ssa_name (i);
struct ptr_info_def *pi;
-
- if (ptr == NULL_TREE)
+
+ if (ptr == NULL_TREE
+ || SSA_NAME_IN_FREE_LIST (ptr))
continue;
pi = SSA_NAME_PTR_INFO (ptr);
- if (!SSA_NAME_IN_FREE_LIST (ptr)
- && pi
- && pi->name_mem_tag)
+ if (pi)
dump_points_to_info_for (file, ptr);
}
- fprintf (file, "\nName memory tags\n\n");
-
- FOR_EACH_REFERENCED_VAR (var, rvi)
- {
- if (TREE_CODE (var) == NAME_MEMORY_TAG)
- dump_variable (file, var);
- }
-
- dump_memory_partitions (file);
-
fprintf (file, "\n");
}
if (pi == NULL)
{
pi = GGC_CNEW (struct ptr_info_def);
+ pt_solution_reset (&pi->pt);
SSA_NAME_PTR_INFO (t) = pi;
}
return pi;
}
+/* Dump the points-to set *PT into FILE. */
+
+void
+dump_points_to_solution (FILE *file, struct pt_solution *pt)
+{
+ if (pt->anything)
+ fprintf (file, ", points-to anything");
+
+ if (pt->nonlocal)
+ fprintf (file, ", points-to non-local");
+
+ if (pt->escaped)
+ fprintf (file, ", points-to escaped");
+
+ if (pt->null)
+ fprintf (file, ", points-to NULL");
+
+ if (pt->vars)
+ {
+ fprintf (file, ", points-to vars: ");
+ dump_decl_set (file, pt->vars);
+ if (pt->vars_contains_global)
+ fprintf (file, " (includes global vars)");
+ }
+}
/* Dump points-to information for SSA_NAME PTR into FILE. */
print_generic_expr (file, ptr, dump_flags);
if (pi)
- {
- if (pi->name_mem_tag)
- {
- fprintf (file, ", name memory tag: ");
- print_generic_expr (file, pi->name_mem_tag, dump_flags);
- }
-
- if (pi->is_dereferenced)
- fprintf (file, ", is dereferenced");
-
- if (pi->value_escapes_p)
- fprintf (file, ", its value escapes");
-
- if (pi->pt_anything)
- fprintf (file, ", points-to anything");
-
- if (pi->pt_null)
- fprintf (file, ", points-to NULL");
-
- if (pi->pt_vars)
- {
- fprintf (file, ", points-to vars: ");
- dump_decl_set (file, pi->pt_vars);
- }
- }
+ dump_points_to_solution (file, &pi->pt);
+ else
+ fprintf (file, ", points-to anything");
fprintf (file, "\n");
}
}
-/* Dump points-to information into FILE. NOTE: This function is slow, as
- it needs to traverse the whole CFG looking for pointer SSA_NAMEs. */
+/* Initializes the alias-oracle reference representation *R from REF. */
void
-dump_points_to_info (FILE *file)
+ao_ref_init (ao_ref *r, tree ref)
{
- basic_block bb;
- block_stmt_iterator si;
- ssa_op_iter iter;
- const char *fname =
- lang_hooks.decl_printable_name (current_function_decl, 2);
- referenced_var_iterator rvi;
- tree var;
+ r->ref = ref;
+ r->base = NULL_TREE;
+ r->offset = 0;
+ r->size = -1;
+ r->max_size = -1;
+ r->ref_alias_set = -1;
+ r->base_alias_set = -1;
+}
- fprintf (file, "\n\nPointed-to sets for pointers in %s\n\n", fname);
+/* Returns the base object of the memory reference *REF. */
- /* First dump points-to information for the default definitions of
- pointer variables. This is necessary because default definitions are
- not part of the code. */
- FOR_EACH_REFERENCED_VAR (var, rvi)
+tree
+ao_ref_base (ao_ref *ref)
+{
+ if (ref->base)
+ return ref->base;
+ ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size,
+ &ref->max_size);
+ return ref->base;
+}
+
+/* Returns the base object alias set of the memory reference *REF. */
+
+static alias_set_type ATTRIBUTE_UNUSED
+ao_ref_base_alias_set (ao_ref *ref)
+{
+ if (ref->base_alias_set != -1)
+ return ref->base_alias_set;
+ ref->base_alias_set = get_alias_set (ao_ref_base (ref));
+ return ref->base_alias_set;
+}
+
+/* Returns the reference alias set of the memory reference *REF. */
+
+alias_set_type
+ao_ref_alias_set (ao_ref *ref)
+{
+ if (ref->ref_alias_set != -1)
+ return ref->ref_alias_set;
+ ref->ref_alias_set = get_alias_set (ref->ref);
+ return ref->ref_alias_set;
+}
+
+/* Init an alias-oracle reference representation from a gimple pointer
+ PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE the the
+ size is assumed to be unknown. The access is assumed to be only
+ to or after of the pointer target, not before it. */
+
+void
+ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size)
+{
+ HOST_WIDE_INT t1, t2;
+ ref->ref = NULL_TREE;
+ if (TREE_CODE (ptr) == ADDR_EXPR)
+ ref->base = get_ref_base_and_extent (TREE_OPERAND (ptr, 0),
+ &ref->offset, &t1, &t2);
+ else
{
- if (POINTER_TYPE_P (TREE_TYPE (var)))
- {
- tree def = gimple_default_def (cfun, var);
- if (def)
- dump_points_to_info_for (file, def);
- }
+ ref->base = build1 (INDIRECT_REF, char_type_node, ptr);
+ ref->offset = 0;
}
+ if (size
+ && host_integerp (size, 0)
+ && TREE_INT_CST_LOW (size) * 8 / 8 == TREE_INT_CST_LOW (size))
+ ref->max_size = ref->size = TREE_INT_CST_LOW (size) * 8;
+ else
+ ref->max_size = ref->size = -1;
+ ref->ref_alias_set = 0;
+ ref->base_alias_set = 0;
+}
- /* Dump points-to information for every pointer defined in the program. */
- FOR_EACH_BB (bb)
- {
- tree phi;
+/* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
+ purpose of TBAA. Return 0 if they are distinct and -1 if we cannot
+ decide. */
- for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
- {
- tree ptr = PHI_RESULT (phi);
- if (POINTER_TYPE_P (TREE_TYPE (ptr)))
- dump_points_to_info_for (file, ptr);
- }
+static inline int
+same_type_for_tbaa (tree type1, tree type2)
+{
+ type1 = TYPE_MAIN_VARIANT (type1);
+ type2 = TYPE_MAIN_VARIANT (type2);
- for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
- {
- 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)))
- dump_points_to_info_for (file, def);
- }
- }
+ /* If we would have to do structural comparison bail out. */
+ if (TYPE_STRUCTURAL_EQUALITY_P (type1)
+ || TYPE_STRUCTURAL_EQUALITY_P (type2))
+ return -1;
- fprintf (file, "\n");
+ /* Compare the canonical types. */
+ if (TYPE_CANONICAL (type1) == TYPE_CANONICAL (type2))
+ return 1;
+
+ /* ??? Array types are not properly unified in all cases as we have
+ spurious changes in the index types for example. Removing this
+ causes all sorts of problems with the Fortran frontend. */
+ if (TREE_CODE (type1) == ARRAY_TYPE
+ && TREE_CODE (type2) == ARRAY_TYPE)
+ return -1;
+
+ /* The types are known to be not equal. */
+ return 0;
}
+/* Determine if the two component references REF1 and REF2 which are
+ based on access types TYPE1 and TYPE2 and of which at least one is based
+ on an indirect reference may alias. */
-/* Dump points-to info pointed to by PTO into STDERR. */
+static bool
+aliasing_component_refs_p (tree ref1, tree type1,
+ HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
+ tree ref2, tree type2,
+ HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
+{
+ /* If one reference is a component references through pointers try to find a
+ common base and apply offset based disambiguation. This handles
+ for example
+ struct A { int i; int j; } *q;
+ struct B { struct A a; int k; } *p;
+ disambiguating q->i and p->a.j. */
+ tree *refp;
+ int same_p;
+
+ /* Now search for the type1 in the access path of ref2. This
+ would be a common base for doing offset based disambiguation on. */
+ refp = &ref2;
+ while (handled_component_p (*refp)
+ && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0)
+ refp = &TREE_OPERAND (*refp, 0);
+ same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1);
+ /* If we couldn't compare types we have to bail out. */
+ if (same_p == -1)
+ return true;
+ else if (same_p == 1)
+ {
+ HOST_WIDE_INT offadj, sztmp, msztmp;
+ get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
+ offset2 -= offadj;
+ return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
+ }
+ /* If we didn't find a common base, try the other way around. */
+ refp = &ref1;
+ while (handled_component_p (*refp)
+ && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0)
+ refp = &TREE_OPERAND (*refp, 0);
+ same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2);
+ /* If we couldn't compare types we have to bail out. */
+ if (same_p == -1)
+ return true;
+ else if (same_p == 1)
+ {
+ HOST_WIDE_INT offadj, sztmp, msztmp;
+ get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp);
+ offset1 -= offadj;
+ return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
+ }
-void
-debug_points_to_info (void)
-{
- dump_points_to_info (stderr);
+ /* We haven't found any common base to apply offset-based disambiguation.
+ There are two cases:
+ 1. The base access types have the same alias set. This can happen
+ in Ada when a function with an unconstrained parameter passed by
+ reference is called on a constrained object and inlined: the types
+ have the same alias set but aren't equivalent. The references may
+ alias in this case.
+ 2. The base access types don't have the same alias set, i.e. one set
+ is a subset of the other. We have proved that B1 is not in the
+ access path B2.path and that B2 is not in the access path B1.path
+ so the references may not alias. */
+ return get_alias_set (type1) == get_alias_set (type2);
}
-/* Dump to FILE the list of variables that may be aliasing VAR. */
+/* Return true if two memory references based on the variables BASE1
+ and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
+ [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */
-void
-dump_may_aliases_for (FILE *file, tree var)
+static bool
+decl_refs_may_alias_p (tree base1,
+ HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
+ tree base2,
+ HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
{
- bitmap aliases;
-
- aliases = MTAG_ALIASES (var);
- if (aliases)
- {
- bitmap_iterator bi;
- unsigned int i;
- tree al;
+ gcc_assert (SSA_VAR_P (base1) && SSA_VAR_P (base2));
- fprintf (file, "{ ");
- EXECUTE_IF_SET_IN_BITMAP (aliases, 0, i, bi)
- {
- al = referenced_var (i);
- print_generic_expr (file, al, dump_flags);
- fprintf (file, " ");
- }
- fprintf (file, "}");
- }
+ /* If both references are based on different variables, they cannot alias. */
+ if (!operand_equal_p (base1, base2, 0))
+ return false;
+
+ /* If both references are based on the same variable, they cannot alias if
+ the accesses do not overlap. */
+ return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
}
+/* Return true if an indirect reference based on *PTR1 constrained
+ to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
+ constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
+ the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
+ in which case they are computed on-demand. REF1 and REF2
+ if non-NULL are the complete memory reference trees. */
+
+static bool
+indirect_ref_may_alias_decl_p (tree ref1, tree ptr1,
+ HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
+ alias_set_type base1_alias_set,
+ tree ref2, tree base2,
+ HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
+ alias_set_type base2_alias_set)
+{
+ /* If only one reference is based on a variable, they cannot alias if
+ the pointer access is beyond the extent of the variable access.
+ (the pointer base cannot validly point to an offset less than zero
+ of the variable).
+ They also cannot alias if the pointer may not point to the decl. */
+ if (max_size2 != -1
+ && !ranges_overlap_p (offset1, max_size1, 0, offset2 + max_size2))
+ return false;
+ if (!ptr_deref_may_alias_decl_p (ptr1, base2))
+ return false;
-/* Dump to stderr the list of variables that may be aliasing VAR. */
+ /* Disambiguations that rely on strict aliasing rules follow. */
+ if (!flag_strict_aliasing)
+ return true;
-void
-debug_may_aliases_for (tree var)
-{
- dump_may_aliases_for (stderr, var);
+ /* If the alias set for a pointer access is zero all bets are off. */
+ if (base1_alias_set == -1)
+ base1_alias_set = get_deref_alias_set (ptr1);
+ if (base1_alias_set == 0)
+ return true;
+ if (base2_alias_set == -1)
+ base2_alias_set = get_alias_set (base2);
+
+ /* If both references are through the same type, they do not alias
+ if the accesses do not overlap. This does extra disambiguation
+ for mixed/pointer accesses but requires strict aliasing. */
+ if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1)),
+ TREE_TYPE (base2)) == 1)
+ return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
+
+ /* The only way to access a variable is through a pointer dereference
+ of the same alias set or a subset of it. */
+ if (base1_alias_set != base2_alias_set
+ && !alias_set_subset_of (base1_alias_set, base2_alias_set))
+ return false;
+
+ /* Do access-path based disambiguation. */
+ if (ref1 && ref2
+ && handled_component_p (ref1)
+ && handled_component_p (ref2))
+ return aliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
+ offset1, max_size1,
+ ref2, TREE_TYPE (base2),
+ offset2, max_size2);
+
+ return true;
}
+/* Return true if two indirect references based on *PTR1
+ and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and
+ [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have
+ the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1
+ in which case they are computed on-demand. REF1 and REF2
+ if non-NULL are the complete memory reference trees. */
-/* Return true if VAR may be aliased. */
+static bool
+indirect_refs_may_alias_p (tree ref1, tree ptr1,
+ HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
+ alias_set_type base1_alias_set,
+ tree ref2, tree ptr2,
+ HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2,
+ alias_set_type base2_alias_set)
+{
+ /* If both bases are based on pointers they cannot alias if they may not
+ point to the same memory object or if they point to the same object
+ and the accesses do not overlap. */
+ if (operand_equal_p (ptr1, ptr2, 0))
+ return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
+ if (!ptr_derefs_may_alias_p (ptr1, ptr2))
+ return false;
-bool
-may_be_aliased (tree var)
-{
- /* Obviously. */
- if (TREE_ADDRESSABLE (var))
+ /* Disambiguations that rely on strict aliasing rules follow. */
+ if (!flag_strict_aliasing)
return true;
- /* Globally visible variables can have their addresses taken by other
- translation units. */
- if (MTAG_P (var)
- && (MTAG_GLOBAL (var) || TREE_PUBLIC (var)))
+ /* If the alias set for a pointer access is zero all bets are off. */
+ if (base1_alias_set == -1)
+ base1_alias_set = get_deref_alias_set (ptr1);
+ if (base1_alias_set == 0)
return true;
- else if (!MTAG_P (var)
- && (DECL_EXTERNAL (var) || TREE_PUBLIC (var)))
+ if (base2_alias_set == -1)
+ base2_alias_set = get_deref_alias_set (ptr2);
+ if (base2_alias_set == 0)
return true;
- /* Automatic variables can't have their addresses escape any other
- way. This must be after the check for global variables, as
- extern declarations do not have TREE_STATIC set. */
- if (!TREE_STATIC (var))
- return false;
+ /* If both references are through the same type, they do not alias
+ if the accesses do not overlap. This does extra disambiguation
+ for mixed/pointer accesses but requires strict aliasing. */
+ if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1)),
+ TREE_TYPE (TREE_TYPE (ptr2))) == 1)
+ return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
- /* If we're in unit-at-a-time mode, then we must have seen all
- occurrences of address-of operators, and so we can trust
- TREE_ADDRESSABLE. Otherwise we can only be sure the variable
- isn't addressable if it's local to the current function. */
- if (flag_unit_at_a_time)
+ /* Do type-based disambiguation. */
+ if (base1_alias_set != base2_alias_set
+ && !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
return false;
- if (decl_function_context (var) == current_function_decl)
- return false;
+ /* Do access-path based disambiguation. */
+ if (ref1 && ref2
+ && handled_component_p (ref1)
+ && handled_component_p (ref2))
+ return aliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
+ offset1, max_size1,
+ ref2, TREE_TYPE (TREE_TYPE (ptr2)),
+ offset2, max_size2);
return true;
}
-
-/* Given two symbols return TRUE if one is in the alias set of the
- other. */
+/* Return true, if the two memory references REF1 and REF2 may alias. */
bool
-is_aliased_with (tree tag, tree sym)
-{
- bitmap aliases;
+refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
+{
+ tree base1, base2;
+ HOST_WIDE_INT offset1 = 0, offset2 = 0;
+ HOST_WIDE_INT max_size1 = -1, max_size2 = -1;
+ bool var1_p, var2_p, ind1_p, ind2_p;
+ alias_set_type set;
+
+ gcc_assert ((!ref1->ref
+ || SSA_VAR_P (ref1->ref)
+ || handled_component_p (ref1->ref)
+ || INDIRECT_REF_P (ref1->ref)
+ || TREE_CODE (ref1->ref) == TARGET_MEM_REF
+ || TREE_CODE (ref1->ref) == CONST_DECL)
+ && (!ref2->ref
+ || SSA_VAR_P (ref2->ref)
+ || handled_component_p (ref2->ref)
+ || INDIRECT_REF_P (ref2->ref)
+ || TREE_CODE (ref2->ref) == TARGET_MEM_REF
+ || TREE_CODE (ref2->ref) == CONST_DECL));
+
+ /* Decompose the references into their base objects and the access. */
+ base1 = ao_ref_base (ref1);
+ offset1 = ref1->offset;
+ max_size1 = ref1->max_size;
+ base2 = ao_ref_base (ref2);
+ offset2 = ref2->offset;
+ max_size2 = ref2->max_size;
+
+ /* We can end up with registers or constants as bases for example from
+ *D.1663_44 = VIEW_CONVERT_EXPR<struct DB_LSN>(__tmp$B0F64_59);
+ which is seen as a struct copy. */
+ if (TREE_CODE (base1) == SSA_NAME
+ || TREE_CODE (base2) == SSA_NAME
+ || TREE_CODE (base1) == CONST_DECL
+ || TREE_CODE (base2) == CONST_DECL
+ || is_gimple_min_invariant (base1)
+ || is_gimple_min_invariant (base2))
+ return false;
- if (MTAG_P (tag))
- {
- aliases = MTAG_ALIASES (tag);
+ /* We can end up refering to code via function decls. As we likely
+ do not properly track code aliases conservatively bail out. */
+ if (TREE_CODE (base1) == FUNCTION_DECL
+ || TREE_CODE (base2) == FUNCTION_DECL)
+ return true;
- if (aliases == NULL)
- return false;
+ /* Defer to simple offset based disambiguation if we have
+ references based on two decls. Do this before defering to
+ TBAA to handle must-alias cases in conformance with the
+ GCC extension of allowing type-punning through unions. */
+ var1_p = SSA_VAR_P (base1);
+ var2_p = SSA_VAR_P (base2);
+ if (var1_p && var2_p)
+ return decl_refs_may_alias_p (base1, offset1, max_size1,
+ base2, offset2, max_size2);
+
+ /* First defer to TBAA if possible. */
+ if (tbaa_p
+ && flag_strict_aliasing
+ && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
+ ao_ref_alias_set (ref2)))
+ return false;
- return bitmap_bit_p (aliases, DECL_UID (sym));
- }
+ /* If one reference is a TARGET_MEM_REF weird things are allowed. Still
+ TBAA disambiguation based on the access type is possible, so bail
+ out only after that check. */
+ if ((ref1->ref && TREE_CODE (ref1->ref) == TARGET_MEM_REF)
+ || (ref2->ref && TREE_CODE (ref2->ref) == TARGET_MEM_REF))
+ return true;
+
+ /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */
+ ind1_p = INDIRECT_REF_P (base1);
+ ind2_p = INDIRECT_REF_P (base2);
+ set = tbaa_p ? -1 : 0;
+ if (var1_p && ind2_p)
+ return indirect_ref_may_alias_decl_p (ref2->ref, TREE_OPERAND (base2, 0),
+ offset2, max_size2, set,
+ ref1->ref, base1,
+ offset1, max_size1, set);
+ else if (ind1_p && var2_p)
+ return indirect_ref_may_alias_decl_p (ref1->ref, TREE_OPERAND (base1, 0),
+ offset1, max_size1, set,
+ ref2->ref, base2,
+ offset2, max_size2, set);
+ else if (ind1_p && ind2_p)
+ return indirect_refs_may_alias_p (ref1->ref, TREE_OPERAND (base1, 0),
+ offset1, max_size1, set,
+ ref2->ref, TREE_OPERAND (base2, 0),
+ offset2, max_size2, set);
+
+ gcc_unreachable ();
+}
+
+bool
+refs_may_alias_p (tree ref1, tree ref2)
+{
+ ao_ref r1, r2;
+ bool res;
+ ao_ref_init (&r1, ref1);
+ ao_ref_init (&r2, ref2);
+ res = refs_may_alias_p_1 (&r1, &r2, true);
+ if (res)
+ ++alias_stats.refs_may_alias_p_may_alias;
else
- {
- gcc_assert (MTAG_P (sym));
- aliases = MTAG_ALIASES (sym);
+ ++alias_stats.refs_may_alias_p_no_alias;
+ return res;
+}
- if (aliases == NULL)
- return false;
+/* Returns true if there is a anti-dependence for the STORE that
+ executes after the LOAD. */
- return bitmap_bit_p (aliases, DECL_UID (tag));
- }
+bool
+refs_anti_dependent_p (tree load, tree store)
+{
+ ao_ref r1, r2;
+ ao_ref_init (&r1, load);
+ ao_ref_init (&r2, store);
+ return refs_may_alias_p_1 (&r1, &r2, false);
+}
- return false;
+/* Returns true if there is a output dependence for the stores
+ STORE1 and STORE2. */
+
+bool
+refs_output_dependent_p (tree store1, tree store2)
+{
+ ao_ref r1, r2;
+ ao_ref_init (&r1, store1);
+ ao_ref_init (&r2, store2);
+ return refs_may_alias_p_1 (&r1, &r2, 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
- is the address of var. Return a memtag for the ptr, after adding the
- proper may_aliases to it (which are the aliases of var, if it has any,
- or var itself). */
+/* If the call CALL may use the memory reference REF return true,
+ otherwise return false. */
-static tree
-add_may_alias_for_new_tag (tree tag, tree var)
+static bool
+ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
{
- bitmap aliases = NULL;
-
- if (MTAG_P (var))
- aliases = may_aliases (var);
+ tree base, callee;
+ unsigned i;
+ int flags = gimple_call_flags (call);
+
+ /* Const functions without a static chain do not implicitly use memory. */
+ if (!gimple_call_chain (call)
+ && (flags & (ECF_CONST|ECF_NOVOPS)))
+ goto process_args;
+
+ base = ao_ref_base (ref);
+ if (!base)
+ return true;
+
+ /* If the reference is based on a decl that is not aliased the call
+ cannot possibly use it. */
+ if (DECL_P (base)
+ && !may_be_aliased (base)
+ /* But local statics can be used through recursion. */
+ && !is_global_var (base))
+ goto process_args;
+
+ callee = gimple_call_fndecl (call);
+
+ /* Handle those builtin functions explicitly that do not act as
+ escape points. See tree-ssa-structalias.c:find_func_aliases
+ for the list of builtins we might need to handle here. */
+ if (callee != NULL_TREE
+ && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
+ switch (DECL_FUNCTION_CODE (callee))
+ {
+ /* All the following functions clobber memory pointed to by
+ their first argument. */
+ case BUILT_IN_STRCPY:
+ case BUILT_IN_STRNCPY:
+ case BUILT_IN_MEMCPY:
+ case BUILT_IN_MEMMOVE:
+ case BUILT_IN_MEMPCPY:
+ case BUILT_IN_STPCPY:
+ case BUILT_IN_STPNCPY:
+ case BUILT_IN_STRCAT:
+ case BUILT_IN_STRNCAT:
+ {
+ ao_ref dref;
+ tree size = NULL_TREE;
+ if (gimple_call_num_args (call) == 3)
+ size = gimple_call_arg (call, 2);
+ ao_ref_init_from_ptr_and_size (&dref,
+ gimple_call_arg (call, 1),
+ size);
+ return refs_may_alias_p_1 (&dref, ref, false);
+ }
+ case BUILT_IN_BCOPY:
+ {
+ ao_ref dref;
+ tree size = gimple_call_arg (call, 2);
+ ao_ref_init_from_ptr_and_size (&dref,
+ gimple_call_arg (call, 0),
+ size);
+ return refs_may_alias_p_1 (&dref, ref, false);
+ }
+ /* The following builtins do not read from memory. */
+ case BUILT_IN_FREE:
+ case BUILT_IN_MALLOC:
+ case BUILT_IN_MEMSET:
+ case BUILT_IN_FREXP:
+ case BUILT_IN_FREXPF:
+ case BUILT_IN_FREXPL:
+ case BUILT_IN_GAMMA_R:
+ case BUILT_IN_GAMMAF_R:
+ case BUILT_IN_GAMMAL_R:
+ case BUILT_IN_LGAMMA_R:
+ case BUILT_IN_LGAMMAF_R:
+ case BUILT_IN_LGAMMAL_R:
+ case BUILT_IN_MODF:
+ case BUILT_IN_MODFF:
+ case BUILT_IN_MODFL:
+ case BUILT_IN_REMQUO:
+ case BUILT_IN_REMQUOF:
+ case BUILT_IN_REMQUOL:
+ case BUILT_IN_SINCOS:
+ case BUILT_IN_SINCOSF:
+ case BUILT_IN_SINCOSL:
+ return false;
+
+ default:
+ /* Fallthru to general call handling. */;
+ }
- /* Case 1: |aliases| == 1 */
- if (aliases && bitmap_count_bits (aliases) == 1)
+ /* Check if base is a global static variable that is not read
+ by the function. */
+ if (TREE_CODE (base) == VAR_DECL
+ && TREE_STATIC (base)
+ && !TREE_PUBLIC (base))
{
- tree ali = referenced_var (bitmap_first_set_bit (aliases));
- if (TREE_CODE (ali) == SYMBOL_MEMORY_TAG)
- return ali;
+ bitmap not_read;
+
+ if (callee != NULL_TREE
+ && (not_read
+ = ipa_reference_get_not_read_global (cgraph_node (callee)))
+ && bitmap_bit_p (not_read, DECL_UID (base)))
+ goto process_args;
}
- /* Case 2: |aliases| == 0 */
- if (aliases == NULL)
- add_may_alias (tag, var);
- else
+ /* If the base variable is call-used or call-clobbered then
+ it may be used. */
+ if (flags & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
{
- /* Case 3: |aliases| > 1 */
- union_alias_set_into (tag, aliases);
+ if (DECL_P (base))
+ {
+ if (is_call_used (base))
+ return true;
+ }
+ else if (INDIRECT_REF_P (base)
+ && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
+ {
+ struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
+ if (!pi)
+ return true;
+
+ if (pt_solution_includes_global (&pi->pt)
+ || pt_solutions_intersect (&cfun->gimple_df->callused, &pi->pt)
+ || pt_solutions_intersect (&cfun->gimple_df->escaped, &pi->pt))
+ return true;
+ }
+ else
+ return true;
}
- return tag;
-}
-
-/* Create a new symbol tag for PTR. Construct the may-alias list of this type
- tag so that it has the aliasing of VAR, or of the relevant subvars of VAR
- according to the location accessed by EXPR.
-
- Note, the set of aliases represented by the new symbol tag are not marked
- for renaming. */
-
-void
-new_type_alias (tree ptr, tree var, tree expr)
-{
- tree tag_type = TREE_TYPE (TREE_TYPE (ptr));
- tree tag;
- subvar_t svars;
- tree ali = NULL_TREE;
- HOST_WIDE_INT offset, size, maxsize;
- tree ref;
- VEC (tree, heap) *overlaps = NULL;
- subvar_t sv;
- unsigned int len;
-
- gcc_assert (symbol_mem_tag (ptr) == NULL_TREE);
- gcc_assert (!MTAG_P (var));
-
- ref = get_ref_base_and_extent (expr, &offset, &size, &maxsize);
- gcc_assert (ref);
-
- tag = create_memory_tag (tag_type, true);
- set_symbol_mem_tag (ptr, tag);
-
- /* Add VAR to the may-alias set of PTR's new symbol tag. If VAR has
- subvars, add the subvars to the tag instead of the actual var. */
- if (var_can_have_subvars (ref)
- && (svars = get_subvars_for_var (ref)))
+ else
{
- for (sv = svars; sv; sv = sv->next)
+ if (DECL_P (base))
+ {
+ if (is_call_clobbered (base))
+ return true;
+ }
+ else if (INDIRECT_REF_P (base)
+ && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
{
- bool exact;
+ struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
+ if (!pi)
+ return true;
- if (overlap_subvar (offset, maxsize, sv->var, &exact))
- VEC_safe_push (tree, heap, overlaps, sv->var);
- }
- gcc_assert (overlaps != NULL);
+ if (pt_solution_includes_global (&pi->pt)
+ || pt_solutions_intersect (&cfun->gimple_df->escaped, &pi->pt))
+ return true;
+ }
+ else
+ return true;
}
- else if (var_can_have_subvars (var)
- && (svars = get_subvars_for_var (var)))
+
+ /* Inspect call arguments for passed-by-value aliases. */
+process_args:
+ for (i = 0; i < gimple_call_num_args (call); ++i)
{
- /* If the REF is not a direct access to VAR (e.g., it is a dereference
- of a pointer), we should scan the virtual operands of REF the same
- way as tree-ssa-operands do. At the moment, this is somewhat
- difficult, so we just give up and add all the subvars of VAR.
- 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);
-
- gcc_assert (overlaps != NULL);
+ tree op = gimple_call_arg (call, i);
+
+ if (TREE_CODE (op) == WITH_SIZE_EXPR)
+ op = TREE_OPERAND (op, 0);
+
+ if (TREE_CODE (op) != SSA_NAME
+ && !is_gimple_min_invariant (op))
+ {
+ ao_ref r;
+ ao_ref_init (&r, op);
+ if (refs_may_alias_p_1 (&r, ref, true))
+ return true;
+ }
}
+
+ return false;
+}
+
+static bool
+ref_maybe_used_by_call_p (gimple call, tree ref)
+{
+ ao_ref r;
+ bool res;
+ ao_ref_init (&r, ref);
+ res = ref_maybe_used_by_call_p_1 (call, &r);
+ if (res)
+ ++alias_stats.ref_maybe_used_by_call_p_may_alias;
else
- ali = add_may_alias_for_new_tag (tag, var);
+ ++alias_stats.ref_maybe_used_by_call_p_no_alias;
+ return res;
+}
+
+
+/* If the statement STMT may use the memory reference REF return
+ true, otherwise return false. */
- len = VEC_length (tree, overlaps);
- if (len > 0)
+bool
+ref_maybe_used_by_stmt_p (gimple stmt, tree ref)
+{
+ if (is_gimple_assign (stmt))
{
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "\nnumber of overlapping subvars = %u\n", len);
+ tree rhs;
- if (len == 1)
- ali = add_may_alias_for_new_tag (tag, VEC_index (tree, overlaps, 0));
- else if (len > 1)
- {
- unsigned int k;
- tree sv_var;
+ /* All memory assign statements are single. */
+ if (!gimple_assign_single_p (stmt))
+ return false;
- for (k = 0; VEC_iterate (tree, overlaps, k, sv_var); k++)
- {
- ali = add_may_alias_for_new_tag (tag, sv_var);
+ rhs = gimple_assign_rhs1 (stmt);
+ if (is_gimple_reg (rhs)
+ || is_gimple_min_invariant (rhs)
+ || gimple_assign_rhs_code (stmt) == CONSTRUCTOR)
+ return false;
- if (ali != tag)
- {
- /* Can happen only if 'Case 1' of add_may_alias_for_new_tag
- took place. Since more than one svar was found, we add
- 'ali' as one of the may_aliases of the new tag. */
- add_may_alias (tag, ali);
- ali = tag;
- }
- }
- }
- VEC_free (tree, heap, overlaps);
+ return refs_may_alias_p (rhs, ref);
}
+ else if (is_gimple_call (stmt))
+ return ref_maybe_used_by_call_p (stmt, ref);
- set_symbol_mem_tag (ptr, ali);
- TREE_READONLY (tag) = TREE_READONLY (var);
- MTAG_GLOBAL (tag) = is_global_var (var);
+ return true;
}
-/* This represents the used range of a variable. */
+/* If the call in statement CALL may clobber the memory reference REF
+ return true, otherwise return false. */
-typedef struct used_part
-{
- HOST_WIDE_INT minused;
- HOST_WIDE_INT maxused;
- /* True if we have an explicit use/def of some portion of this variable,
- even if it is all of it. i.e. a.b = 5 or temp = a.b. */
- bool explicit_uses;
- /* True if we have an implicit use/def of some portion of this
- variable. Implicit uses occur when we can't tell what part we
- are referencing, and have to make conservative assumptions. */
- bool implicit_uses;
- /* True if the structure is only written to or taken its address. */
- bool write_only;
-} *used_part_t;
-
-/* An array of used_part structures, indexed by variable uid. */
-
-static htab_t used_portions;
-
-struct used_part_map
+static bool
+call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
{
- unsigned int uid;
- used_part_t to;
-};
+ tree base;
+ tree callee;
-/* Return true if the uid in the two used part maps are equal. */
+ /* If the call is pure or const it cannot clobber anything. */
+ if (gimple_call_flags (call)
+ & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS))
+ return false;
-static int
-used_part_map_eq (const void *va, const void *vb)
-{
- const struct used_part_map *a = (const struct used_part_map *) va;
- const struct used_part_map *b = (const struct used_part_map *) vb;
- return (a->uid == b->uid);
-}
+ base = ao_ref_base (ref);
+ if (!base)
+ return true;
-/* Hash a from uid in a used_part_map. */
+ if (TREE_CODE (base) == SSA_NAME
+ || CONSTANT_CLASS_P (base))
+ return false;
-static unsigned int
-used_part_map_hash (const void *item)
-{
- return ((const struct used_part_map *)item)->uid;
-}
+ /* If the reference is based on a decl that is not aliased the call
+ cannot possibly clobber it. */
+ if (DECL_P (base)
+ && !may_be_aliased (base)
+ /* But local non-readonly statics can be modified through recursion
+ or the call may implement a threading barrier which we must
+ treat as may-def. */
+ && (TREE_READONLY (base)
+ || !is_global_var (base)))
+ return false;
-/* Free a used part map element. */
+ callee = gimple_call_fndecl (call);
-static void
-free_used_part_map (void *item)
-{
- free (((struct used_part_map *)item)->to);
- free (item);
-}
+ /* Handle those builtin functions explicitly that do not act as
+ escape points. See tree-ssa-structalias.c:find_func_aliases
+ for the list of builtins we might need to handle here. */
+ if (callee != NULL_TREE
+ && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
+ switch (DECL_FUNCTION_CODE (callee))
+ {
+ /* All the following functions clobber memory pointed to by
+ their first argument. */
+ case BUILT_IN_STRCPY:
+ case BUILT_IN_STRNCPY:
+ case BUILT_IN_MEMCPY:
+ case BUILT_IN_MEMMOVE:
+ case BUILT_IN_MEMPCPY:
+ case BUILT_IN_STPCPY:
+ case BUILT_IN_STPNCPY:
+ case BUILT_IN_STRCAT:
+ case BUILT_IN_STRNCAT:
+ case BUILT_IN_MEMSET:
+ {
+ ao_ref dref;
+ tree size = NULL_TREE;
+ if (gimple_call_num_args (call) == 3)
+ size = gimple_call_arg (call, 2);
+ ao_ref_init_from_ptr_and_size (&dref,
+ gimple_call_arg (call, 0),
+ size);
+ return refs_may_alias_p_1 (&dref, ref, false);
+ }
+ case BUILT_IN_BCOPY:
+ {
+ ao_ref dref;
+ tree size = gimple_call_arg (call, 2);
+ ao_ref_init_from_ptr_and_size (&dref,
+ gimple_call_arg (call, 1),
+ size);
+ return refs_may_alias_p_1 (&dref, ref, false);
+ }
+ /* Allocating memory does not have any side-effects apart from
+ being the definition point for the pointer. */
+ case BUILT_IN_MALLOC:
+ return false;
+ /* Freeing memory kills the pointed-to memory. More importantly
+ the call has to serve as a barrier for moving loads and stores
+ across it. */
+ case BUILT_IN_FREE:
+ {
+ tree ptr = gimple_call_arg (call, 0);
+ return ptr_deref_may_alias_ref_p_1 (ptr, ref);
+ }
+ case BUILT_IN_GAMMA_R:
+ case BUILT_IN_GAMMAF_R:
+ case BUILT_IN_GAMMAL_R:
+ case BUILT_IN_LGAMMA_R:
+ case BUILT_IN_LGAMMAF_R:
+ case BUILT_IN_LGAMMAL_R:
+ {
+ tree out = gimple_call_arg (call, 1);
+ if (ptr_deref_may_alias_ref_p_1 (out, ref))
+ return true;
+ if (flag_errno_math)
+ break;
+ return false;
+ }
+ case BUILT_IN_FREXP:
+ case BUILT_IN_FREXPF:
+ case BUILT_IN_FREXPL:
+ case BUILT_IN_MODF:
+ case BUILT_IN_MODFF:
+ case BUILT_IN_MODFL:
+ {
+ tree out = gimple_call_arg (call, 1);
+ return ptr_deref_may_alias_ref_p_1 (out, ref);
+ }
+ case BUILT_IN_REMQUO:
+ case BUILT_IN_REMQUOF:
+ case BUILT_IN_REMQUOL:
+ {
+ tree out = gimple_call_arg (call, 2);
+ if (ptr_deref_may_alias_ref_p_1 (out, ref))
+ return true;
+ if (flag_errno_math)
+ break;
+ return false;
+ }
+ case BUILT_IN_SINCOS:
+ case BUILT_IN_SINCOSF:
+ case BUILT_IN_SINCOSL:
+ {
+ tree sin = gimple_call_arg (call, 1);
+ tree cos = gimple_call_arg (call, 2);
+ return (ptr_deref_may_alias_ref_p_1 (sin, ref)
+ || ptr_deref_may_alias_ref_p_1 (cos, ref));
+ }
+ default:
+ /* Fallthru to general call handling. */;
+ }
-/* Lookup a used_part structure for a UID. */
+ /* Check if base is a global static variable that is not written
+ by the function. */
+ if (callee != NULL_TREE
+ && TREE_CODE (base) == VAR_DECL
+ && TREE_STATIC (base)
+ && !TREE_PUBLIC (base))
+ {
+ bitmap not_written;
-static used_part_t
-up_lookup (unsigned int uid)
-{
- struct used_part_map *h, in;
- in.uid = uid;
- h = (struct used_part_map *) htab_find_with_hash (used_portions, &in, uid);
- if (!h)
- return NULL;
- return h->to;
+ if ((not_written
+ = ipa_reference_get_not_written_global (cgraph_node (callee)))
+ && bitmap_bit_p (not_written, DECL_UID (base)))
+ return false;
+ }
+
+ if (DECL_P (base))
+ return is_call_clobbered (base);
+ else if (INDIRECT_REF_P (base)
+ && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
+ {
+ struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
+ if (!pi)
+ return true;
+
+ return (pt_solution_includes_global (&pi->pt)
+ || pt_solutions_intersect (&cfun->gimple_df->escaped, &pi->pt));
+ }
+
+ return true;
}
-/* Insert the pair UID, TO into the used part hashtable. */
-
-static void
-up_insert (unsigned int uid, used_part_t to)
-{
- struct used_part_map *h;
- void **loc;
-
- h = XNEW (struct used_part_map);
- h->uid = uid;
- h->to = to;
- loc = htab_find_slot_with_hash (used_portions, h,
- uid, INSERT);
- if (*loc != NULL)
- free (*loc);
- *(struct used_part_map **) loc = h;
+static bool ATTRIBUTE_UNUSED
+call_may_clobber_ref_p (gimple call, tree ref)
+{
+ bool res;
+ ao_ref r;
+ ao_ref_init (&r, ref);
+ res = call_may_clobber_ref_p_1 (call, &r);
+ if (res)
+ ++alias_stats.call_may_clobber_ref_p_may_alias;
+ else
+ ++alias_stats.call_may_clobber_ref_p_no_alias;
+ return res;
}
-/* Given a variable uid, UID, get or create the entry in the used portions
- table for the variable. */
+/* If the statement STMT may clobber the memory reference REF return true,
+ otherwise return false. */
-static used_part_t
-get_or_create_used_part_for (size_t uid)
+bool
+stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref)
{
- used_part_t up;
- if ((up = up_lookup (uid)) == NULL)
+ if (is_gimple_call (stmt))
+ {
+ tree lhs = gimple_call_lhs (stmt);
+ if (lhs
+ && !is_gimple_reg (lhs))
+ {
+ ao_ref r;
+ ao_ref_init (&r, lhs);
+ if (refs_may_alias_p_1 (ref, &r, true))
+ return true;
+ }
+
+ return call_may_clobber_ref_p_1 (stmt, ref);
+ }
+ else if (is_gimple_assign (stmt))
{
- up = XCNEW (struct used_part);
- up->minused = INT_MAX;
- up->maxused = 0;
- up->explicit_uses = false;
- up->implicit_uses = false;
- up->write_only = true;
+ ao_ref r;
+ ao_ref_init (&r, gimple_assign_lhs (stmt));
+ return refs_may_alias_p_1 (ref, &r, true);
}
+ else if (gimple_code (stmt) == GIMPLE_ASM)
+ return true;
- return up;
+ return false;
}
-
-/* Create and return a structure sub-variable for field type FIELD at
- offset OFFSET, with size SIZE, of variable VAR. */
-
-static tree
-create_sft (tree var, tree field, unsigned HOST_WIDE_INT offset,
- unsigned HOST_WIDE_INT size)
+bool
+stmt_may_clobber_ref_p (gimple stmt, tree ref)
{
- tree subvar = create_tag_raw (STRUCT_FIELD_TAG, field, "SFT");
-
- /* We need to copy the various flags from VAR to SUBVAR, so that
- they are is_global_var iff the original variable was. */
- DECL_CONTEXT (subvar) = DECL_CONTEXT (var);
- MTAG_GLOBAL (subvar) = DECL_EXTERNAL (var);
- TREE_PUBLIC (subvar) = TREE_PUBLIC (var);
- TREE_STATIC (subvar) = TREE_STATIC (var);
- TREE_READONLY (subvar) = TREE_READONLY (var);
- TREE_ADDRESSABLE (subvar) = TREE_ADDRESSABLE (var);
-
- /* Add the new variable to REFERENCED_VARS. */
- set_symbol_mem_tag (subvar, NULL);
- add_referenced_var (subvar);
- SFT_PARENT_VAR (subvar) = var;
- SFT_OFFSET (subvar) = offset;
- SFT_SIZE (subvar) = size;
- return subvar;
+ ao_ref r;
+ ao_ref_init (&r, ref);
+ return stmt_may_clobber_ref_p_1 (stmt, &r);
}
-/* Given an aggregate VAR, create the subvariables that represent its
- fields. */
+/* Walk the virtual use-def chain of VUSE until hitting the virtual operand
+ TARGET or a statement clobbering the memory reference REF in which
+ case false is returned. The walk starts with VUSE, one argument of PHI. */
-static void
-create_overlap_variables_for (tree var)
+static bool
+maybe_skip_until (gimple phi, tree target, ao_ref *ref,
+ tree vuse, bitmap *visited)
{
- VEC(fieldoff_s,heap) *fieldstack = NULL;
- used_part_t up;
- size_t uid = DECL_UID (var);
+ if (!*visited)
+ *visited = BITMAP_ALLOC (NULL);
- up = up_lookup (uid);
- if (!up
- || up->write_only)
- return;
+ bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi)));
- push_fields_onto_fieldstack (TREE_TYPE (var), &fieldstack, 0, NULL);
- if (VEC_length (fieldoff_s, fieldstack) != 0)
+ /* Walk until we hit the target. */
+ while (vuse != target)
{
- subvar_t *subvars;
- fieldoff_s *fo;
- bool notokay = false;
- int fieldcount = 0;
- int i;
- HOST_WIDE_INT lastfooffset = -1;
- HOST_WIDE_INT lastfosize = -1;
- tree lastfotype = NULL_TREE;
-
- /* Not all fields have DECL_SIZE set, and those that don't, we don't
- know their size, and thus, can't handle.
- The same is true of fields with DECL_SIZE that is not an integer
- constant (such as variable sized fields).
- Fields with offsets which are not constant will have an offset < 0
- We *could* handle fields that are constant sized arrays, but
- currently don't. Doing so would require some extra changes to
- tree-ssa-operands.c. */
-
- for (i = 0; VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
+ gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
+ /* Recurse for PHI nodes. */
+ if (gimple_code (def_stmt) == GIMPLE_PHI)
{
- if (!fo->size
- || TREE_CODE (fo->size) != INTEGER_CST
- || fo->offset < 0)
- {
- notokay = true;
- break;
- }
- fieldcount++;
+ /* An already visited PHI node ends the walk successfully. */
+ if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt))))
+ return true;
+ vuse = get_continuation_for_phi (def_stmt, ref, visited);
+ if (!vuse)
+ return false;
+ continue;
}
+ /* A clobbering statement or the end of the IL ends it failing. */
+ else if (gimple_nop_p (def_stmt)
+ || stmt_may_clobber_ref_p_1 (def_stmt, ref))
+ return false;
+ vuse = gimple_vuse (def_stmt);
+ }
+ return true;
+}
- /* The current heuristic we use is as follows:
- If the variable has no used portions in this function, no
- structure vars are created for it.
- Otherwise,
- If the variable has less than SALIAS_MAX_IMPLICIT_FIELDS,
- we always create structure vars for them.
- If the variable has more than SALIAS_MAX_IMPLICIT_FIELDS, and
- some explicit uses, we create structure vars for them.
- If the variable has more than SALIAS_MAX_IMPLICIT_FIELDS, and
- no explicit uses, we do not create structure vars for them.
- */
-
- if (fieldcount >= SALIAS_MAX_IMPLICIT_FIELDS
- && !up->explicit_uses)
+/* Starting from a PHI node for the virtual operand of the memory reference
+ REF find a continuation virtual operand that allows to continue walking
+ statements dominating PHI skipping only statements that cannot possibly
+ clobber REF. Returns NULL_TREE if no suitable virtual operand can
+ be found. */
+
+tree
+get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited)
+{
+ unsigned nargs = gimple_phi_num_args (phi);
+
+ /* Through a single-argument PHI we can simply look through. */
+ if (nargs == 1)
+ return PHI_ARG_DEF (phi, 0);
+
+ /* For two arguments try to skip non-aliasing code until we hit
+ the phi argument definition that dominates the other one. */
+ if (nargs == 2)
+ {
+ tree arg0 = PHI_ARG_DEF (phi, 0);
+ tree arg1 = PHI_ARG_DEF (phi, 1);
+ gimple def0 = SSA_NAME_DEF_STMT (arg0);
+ gimple def1 = SSA_NAME_DEF_STMT (arg1);
+ tree common_vuse;
+
+ if (arg0 == arg1)
+ return arg0;
+ else if (gimple_nop_p (def0)
+ || (!gimple_nop_p (def1)
+ && dominated_by_p (CDI_DOMINATORS,
+ gimple_bb (def1), gimple_bb (def0))))
{
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "Variable ");
- print_generic_expr (dump_file, var, 0);
- fprintf (dump_file, " has no explicit uses in this function, and is > SALIAS_MAX_IMPLICIT_FIELDS, so skipping\n");
- }
- notokay = true;
+ if (maybe_skip_until (phi, arg0, ref, arg1, visited))
+ return arg0;
}
-
- /* Bail out, if we can't create overlap variables. */
- if (notokay)
+ else if (gimple_nop_p (def1)
+ || dominated_by_p (CDI_DOMINATORS,
+ gimple_bb (def0), gimple_bb (def1)))
{
- VEC_free (fieldoff_s, heap, fieldstack);
- return;
+ if (maybe_skip_until (phi, arg1, ref, arg0, visited))
+ return arg1;
}
-
- /* Otherwise, create the variables. */
- subvars = lookup_subvars_for_var (var);
-
- sort_fieldstack (fieldstack);
-
- for (i = VEC_length (fieldoff_s, fieldstack);
- VEC_iterate (fieldoff_s, fieldstack, --i, fo);)
+ /* Special case of a diamond:
+ MEM_1 = ...
+ goto (cond) ? L1 : L2
+ L1: store1 = ... #MEM_2 = vuse(MEM_1)
+ goto L3
+ L2: store2 = ... #MEM_3 = vuse(MEM_1)
+ L3: MEM_4 = PHI<MEM_2, MEM_3>
+ We were called with the PHI at L3, MEM_2 and MEM_3 don't
+ dominate each other, but still we can easily skip this PHI node
+ if we recognize that the vuse MEM operand is the same for both,
+ and that we can skip both statements (they don't clobber us).
+ This is still linear. Don't use maybe_skip_until, that might
+ potentially be slow. */
+ else if ((common_vuse = gimple_vuse (def0))
+ && common_vuse == gimple_vuse (def1))
{
- subvar_t sv;
- HOST_WIDE_INT fosize;
- tree currfotype;
-
- 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)
- || (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);
-
- if (dump_file)
- {
- fprintf (dump_file, "structure field tag %s created for var %s",
- get_name (sv->var), get_name (var));
- fprintf (dump_file, " offset " HOST_WIDE_INT_PRINT_DEC,
- SFT_OFFSET (sv->var));
- fprintf (dump_file, " size " HOST_WIDE_INT_PRINT_DEC,
- SFT_SIZE (sv->var));
- fprintf (dump_file, "\n");
- }
-
- lastfotype = currfotype;
- lastfooffset = fo->offset;
- lastfosize = fosize;
- *subvars = sv;
+ if (!stmt_may_clobber_ref_p_1 (def0, ref)
+ && !stmt_may_clobber_ref_p_1 (def1, ref))
+ return common_vuse;
}
-
- /* Once we have created subvars, the original is no longer call
- clobbered on its own. Its call clobbered status depends
- completely on the call clobbered status of the subvars.
-
- add_referenced_var in the above loop will take care of
- marking subvars of global variables as call clobbered for us
- to start, since they are global as well. */
- clear_call_clobbered (var);
}
- VEC_free (fieldoff_s, heap, fieldstack);
+ return NULL_TREE;
}
+/* Based on the memory reference REF and its virtual use VUSE call
+ WALKER for each virtual use that is equivalent to VUSE, including VUSE
+ itself. That is, for each virtual use for which its defining statement
+ does not clobber REF.
-/* Find the conservative answer to the question of what portions of what
- structures are used by this statement. We assume that if we have a
- component ref with a known size + offset, that we only need that part
- of the structure. For unknown cases, or cases where we do something
- to the whole structure, we assume we need to create fields for the
- entire structure. */
-
-static tree
-find_used_portions (tree *tp, int *walk_subtrees, void *lhs_p)
-{
- switch (TREE_CODE (*tp))
- {
- case GIMPLE_MODIFY_STMT:
- /* Recurse manually here to track whether the use is in the
- LHS of an assignment. */
- find_used_portions (&GIMPLE_STMT_OPERAND (*tp, 0), walk_subtrees, tp);
- return find_used_portions (&GIMPLE_STMT_OPERAND (*tp, 1),
- walk_subtrees, NULL);
- case REALPART_EXPR:
- case IMAGPART_EXPR:
- case COMPONENT_REF:
- case ARRAY_REF:
- {
- HOST_WIDE_INT bitsize;
- HOST_WIDE_INT bitmaxsize;
- HOST_WIDE_INT bitpos;
- tree ref;
- ref = get_ref_base_and_extent (*tp, &bitpos, &bitsize, &bitmaxsize);
- if (DECL_P (ref)
- && var_can_have_subvars (ref)
- && bitmaxsize != -1)
- {
- size_t uid = DECL_UID (ref);
- used_part_t up;
-
- up = get_or_create_used_part_for (uid);
-
- if (bitpos <= up->minused)
- up->minused = bitpos;
- if ((bitpos + bitmaxsize >= up->maxused))
- up->maxused = bitpos + bitmaxsize;
-
- if (bitsize == bitmaxsize)
- up->explicit_uses = true;
- else
- up->implicit_uses = true;
- if (!lhs_p)
- up->write_only = false;
- up_insert (uid, up);
-
- *walk_subtrees = 0;
- return NULL_TREE;
- }
- }
- break;
- /* This is here to make sure we mark the entire base variable as used
- when you take its address. Because our used portion analysis is
- simple, we aren't looking at casts or pointer arithmetic to see what
- happens when you take the address. */
- case ADDR_EXPR:
- {
- tree var = get_base_address (TREE_OPERAND (*tp, 0));
+ WALKER is called with REF, the current virtual use and DATA. If
+ WALKER returns non-NULL the walk stops and its result is returned.
+ At the end of a non-successful walk NULL is returned.
- if (var
- && DECL_P (var)
- && DECL_SIZE (var)
- && var_can_have_subvars (var)
- && TREE_CODE (DECL_SIZE (var)) == INTEGER_CST)
- {
- used_part_t up;
- size_t uid = DECL_UID (var);
-
- up = get_or_create_used_part_for (uid);
-
- up->minused = 0;
- up->maxused = TREE_INT_CST_LOW (DECL_SIZE (var));
- up->implicit_uses = true;
- if (!lhs_p)
- up->write_only = false;
-
- up_insert (uid, up);
- *walk_subtrees = 0;
- return NULL_TREE;
- }
- }
- break;
- case CALL_EXPR:
- {
- tree *arg;
- for (arg = &TREE_OPERAND (*tp, 1); *arg; arg = &TREE_CHAIN (*arg))
- {
- if (TREE_CODE (TREE_VALUE (*arg)) != ADDR_EXPR)
- find_used_portions (&TREE_VALUE (*arg), walk_subtrees, NULL);
- }
- *walk_subtrees = 0;
- return NULL_TREE;
- }
- case VAR_DECL:
- case PARM_DECL:
- case RESULT_DECL:
- {
- tree var = *tp;
- if (DECL_SIZE (var)
- && var_can_have_subvars (var)
- && TREE_CODE (DECL_SIZE (var)) == INTEGER_CST)
- {
- used_part_t up;
- size_t uid = DECL_UID (var);
-
- up = get_or_create_used_part_for (uid);
-
- up->minused = 0;
- up->maxused = TREE_INT_CST_LOW (DECL_SIZE (var));
- up->implicit_uses = true;
-
- up_insert (uid, up);
- *walk_subtrees = 0;
- return NULL_TREE;
- }
- }
- break;
-
- default:
- break;
-
- }
- return NULL_TREE;
-}
+ TRANSLATE if non-NULL is called with a pointer to REF, the virtual
+ use which definition is a statement that may clobber REF and DATA.
+ If TRANSLATE returns (void *)-1 the walk stops and NULL is returned.
+ If TRANSLATE returns non-NULL the walk stops and its result is returned.
+ If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed
+ to adjust REF and *DATA to make that valid.
-/* Create structure field variables for structures used in this function. */
+ TODO: Cache the vector of equivalent vuses per ref, vuse pair. */
-static unsigned int
-create_structure_vars (void)
+void *
+walk_non_aliased_vuses (ao_ref *ref, tree vuse,
+ void *(*walker)(ao_ref *, tree, void *),
+ void *(*translate)(ao_ref *, tree, void *), void *data)
{
- basic_block bb;
- safe_referenced_var_iterator rvi;
- VEC (tree, heap) *varvec = NULL;
- tree var;
+ bitmap visited = NULL;
+ void *res;
- used_portions = htab_create (10, used_part_map_hash, used_part_map_eq,
- free_used_part_map);
-
- FOR_EACH_BB (bb)
- {
- block_stmt_iterator bsi;
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
- {
- walk_tree_without_duplicates (bsi_stmt_ptr (bsi),
- find_used_portions,
- NULL);
- }
- }
- FOR_EACH_REFERENCED_VAR_SAFE (var, varvec, rvi)
+ timevar_push (TV_ALIAS_STMT_WALK);
+
+ do
{
- /* The C++ FE creates vars without DECL_SIZE set, for some reason. */
- if (var
- && DECL_SIZE (var)
- && var_can_have_subvars (var)
- && !MTAG_P (var)
- && TREE_CODE (DECL_SIZE (var)) == INTEGER_CST)
- create_overlap_variables_for (var);
- }
- htab_delete (used_portions);
- VEC_free (tree, heap, varvec);
+ gimple def_stmt;
- /* Update SSA operands of statements mentioning variables we split. */
- if (gimple_in_ssa_p (cfun))
- FOR_EACH_BB (bb)
- {
- block_stmt_iterator bsi;
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
- {
- tree stmt = bsi_stmt (bsi);
- bool update = false;
- unsigned int i;
- bitmap_iterator bi;
+ /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
+ res = (*walker) (ref, vuse, data);
+ if (res)
+ break;
- if (STORED_SYMS (stmt))
- EXECUTE_IF_SET_IN_BITMAP (STORED_SYMS (stmt), 0, i, bi)
+ def_stmt = SSA_NAME_DEF_STMT (vuse);
+ if (gimple_nop_p (def_stmt))
+ break;
+ else if (gimple_code (def_stmt) == GIMPLE_PHI)
+ vuse = get_continuation_for_phi (def_stmt, ref, &visited);
+ else
+ {
+ if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
+ {
+ if (!translate)
+ break;
+ res = (*translate) (ref, vuse, data);
+ /* Failed lookup and translation. */
+ if (res == (void *)-1)
{
- tree sym = referenced_var_lookup (i);
- if (get_subvars_for_var (sym))
- {
- update=true;
- break;
- }
+ res = NULL;
+ break;
}
+ /* Lookup succeeded. */
+ else if (res != NULL)
+ break;
+ /* Translation succeeded, continue walking. */
+ }
+ vuse = gimple_vuse (def_stmt);
+ }
+ }
+ while (vuse);
- if (LOADED_SYMS (stmt) && !update)
- EXECUTE_IF_SET_IN_BITMAP (LOADED_SYMS (stmt), 0, i, bi)
- {
- tree sym = referenced_var_lookup (i);
- if (get_subvars_for_var (sym))
- {
- update=true;
- break;
- }
- }
+ if (visited)
+ BITMAP_FREE (visited);
- if (stmt_ann (stmt)->addresses_taken && !update)
- EXECUTE_IF_SET_IN_BITMAP (stmt_ann (stmt)->addresses_taken,
- 0, i, bi)
- {
- tree sym = referenced_var_lookup (i);
- if (get_subvars_for_var (sym))
- {
- update=true;
- break;
- }
- }
+ timevar_pop (TV_ALIAS_STMT_WALK);
- if (update)
- update_stmt (stmt);
- }
- }
-
- return 0;
+ return res;
}
-static bool
-gate_structure_vars (void)
-{
- return flag_tree_salias != 0;
-}
-struct tree_opt_pass pass_create_structure_vars =
-{
- "salias", /* name */
- gate_structure_vars, /* gate */
- create_structure_vars, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- 0, /* tv_id */
- PROP_cfg, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func, /* todo_flags_finish */
- 0 /* letter */
-};
-
-/* Reset the call_clobbered flags on our referenced vars. In
- theory, this only needs to be done for globals. */
+/* Based on the memory reference REF call WALKER for each vdef which
+ defining statement may clobber REF, starting with VDEF. If REF
+ is NULL_TREE, each defining statement is visited.
+
+ WALKER is called with REF, the current vdef and DATA. If WALKER
+ returns true the walk is stopped, otherwise it continues.
+
+ At PHI nodes walk_aliased_vdefs forks into one walk for reach
+ PHI argument (but only one walk continues on merge points), the
+ return value is true if any of the walks was successful.
+
+ The function returns the number of statements walked. */
static unsigned int
-reset_cc_flags (void)
+walk_aliased_vdefs_1 (ao_ref *ref, tree vdef,
+ bool (*walker)(ao_ref *, tree, void *), void *data,
+ bitmap *visited, unsigned int cnt)
{
- tree var;
- referenced_var_iterator rvi;
+ do
+ {
+ gimple def_stmt = SSA_NAME_DEF_STMT (vdef);
- FOR_EACH_REFERENCED_VAR (var, rvi)
- var_ann (var)->call_clobbered = false;
- return 0;
+ if (*visited
+ && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef)))
+ return cnt;
+
+ if (gimple_nop_p (def_stmt))
+ return cnt;
+ else if (gimple_code (def_stmt) == GIMPLE_PHI)
+ {
+ unsigned i;
+ if (!*visited)
+ *visited = BITMAP_ALLOC (NULL);
+ for (i = 0; i < gimple_phi_num_args (def_stmt); ++i)
+ cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i),
+ walker, data, visited, 0);
+ return cnt;
+ }
+
+ /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
+ cnt++;
+ if ((!ref
+ || stmt_may_clobber_ref_p_1 (def_stmt, ref))
+ && (*walker) (ref, vdef, data))
+ return cnt;
+
+ vdef = gimple_vuse (def_stmt);
+ }
+ while (1);
}
-struct tree_opt_pass pass_reset_cc_flags =
+unsigned int
+walk_aliased_vdefs (ao_ref *ref, tree vdef,
+ bool (*walker)(ao_ref *, tree, void *), void *data,
+ bitmap *visited)
{
- NULL, /* name */
- NULL, /* gate */
- reset_cc_flags, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- 0, /* tv_id */
- PROP_referenced_vars |PROP_cfg, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- 0, /* todo_flags_finish */
- 0 /* letter */
-};
+ bitmap local_visited = NULL;
+ unsigned int ret;
+
+ timevar_push (TV_ALIAS_STMT_WALK);
+
+ ret = walk_aliased_vdefs_1 (ref, vdef, walker, data,
+ visited ? visited : &local_visited, 0);
+ if (local_visited)
+ BITMAP_FREE (local_visited);
+
+ timevar_pop (TV_ALIAS_STMT_WALK);
+
+ return ret;
+}
+
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