/* Alias analysis for trees.
- Copyright (C) 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
+the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful,
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to
-the Free Software Foundation, 51 Franklin Street, Fifth Floor,
-Boston, MA 02110-1301, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "ipa-type-escape.h"
#include "vec.h"
#include "bitmap.h"
+#include "vecprim.h"
+#include "pointer-set.h"
+#include "alloc-pool.h"
-/* Obstack used to hold grouping bitmaps and other temporary bitmaps used by
- aliasing */
-static bitmap_obstack alias_obstack;
+/* Broad overview of how aliasing works:
+
+ First we compute points-to sets, which is done in
+ tree-ssa-structalias.c
+
+ During points-to set constraint finding, a bunch of little bits of
+ information is collected.
+ This is not done because it is necessary for points-to, but because
+ points-to has to walk every statement anyway. The function performing
+ this collecting is update_alias_info.
+
+ Bits update_alias_info collects include:
+ 1. Directly escaping variables and variables whose value escapes
+ (using is_escape_site). This is the set of variables and values that
+ escape prior to transitive closure of the clobbers.
+ 2. The set of variables dereferenced on the LHS (into
+ dereferenced_ptr_stores)
+ 3. The set of variables dereferenced on the RHS (into
+ dereferenced_ptr_loads)
+ 4. The set of all pointers we saw.
+ 5. The number of loads and stores for each variable
+ 6. The number of statements touching memory
+ 7. The set of address taken variables.
+
+
+ #1 is computed by a combination of is_escape_site, and counting the
+ number of uses/deref operators. This function properly accounts for
+ situations like &ptr->field, which is *not* a dereference.
+
+ After points-to sets are computed, the sets themselves still
+ contain points-to specific variables, such as a variable that says
+ the pointer points to anything, a variable that says the pointer
+ points to readonly memory, etc.
+
+ These are eliminated in a later phase, as we will see.
+
+ The rest of the phases are located in tree-ssa-alias.c
+
+ The next phase after points-to set computation is called
+ "setup_pointers_and_addressables"
+
+ This pass does 3 main things:
+
+ 1. All variables that can have TREE_ADDRESSABLE removed safely (IE
+ non-globals whose address is not taken), have TREE_ADDRESSABLE
+ removed.
+ 2. All variables that may be aliased (which is the set of addressable
+ variables and globals) at all, are marked for renaming, and have
+ symbol memory tags created for them.
+ 3. All variables which are stored into have their SMT's added to
+ written vars.
+
+
+ After this function is run, all variables that will ever have an
+ SMT, have one, though its aliases are not filled in.
+
+ The next phase is to compute flow-insensitive aliasing, which in
+ our case, is a misnomer. it is really computing aliasing that
+ requires no transitive closure to be correct. In particular, it
+ uses stack vs non-stack, TBAA, etc, to determine whether two
+ symbols could *ever* alias . This phase works by going through all
+ the pointers we collected during update_alias_info, and for every
+ addressable variable in the program, seeing if they alias. If so,
+ the addressable variable is added to the symbol memory tag for the
+ pointer.
+
+ As part of this, we handle symbol memory tags that conflict but
+ have no aliases in common, by forcing them to have a symbol in
+ common (through unioning alias sets or adding one as an alias of
+ the other), or by adding one as an alias of another. The case of
+ conflicts with no aliases in common occurs mainly due to aliasing
+ we cannot see. In particular, it generally means we have a load
+ through a pointer whose value came from outside the function.
+ Without an addressable symbol to point to, they would get the wrong
+ answer.
+
+ After flow insensitive aliasing is computed, we compute name tags
+ (called compute_flow_sensitive_info). We walk each pointer we
+ collected and see if it has a usable points-to set. If so, we
+ generate a name tag using that pointer, and make an alias bitmap for
+ it. Name tags are shared between all things with the same alias
+ bitmap. The alias bitmap will be translated from what points-to
+ computed. In particular, the "anything" variable in points-to will be
+ transformed into a pruned set of SMT's and their aliases that
+ compute_flow_insensitive_aliasing computed.
+ Note that since 4.3, every pointer that points-to computed a solution for
+ will get a name tag (whereas before 4.3, only those whose set did
+ *not* include the anything variable would). At the point where name
+ tags are all assigned, symbol memory tags are dead, and could be
+ deleted, *except* on global variables. Global variables still use
+ symbol memory tags as of right now.
+
+ After name tags are computed, the set of clobbered variables is
+ transitively closed. In particular, we compute the set of clobbered
+ variables based on the initial set of clobbers, plus the aliases of
+ pointers which either escape, or have their value escape.
+
+ After this, maybe_create_global_var is run, which handles a corner
+ case where we have no call clobbered variables, but have pure and
+ non-pure functions.
+
+ Staring at this function, I now remember it is a hack for the fact
+ that we do not mark all globals in the program as call clobbered for a
+ function unless they are actually used in that function. Instead, we
+ only mark the set that is actually clobbered. As a result, you can
+ end up with situations where you have no call clobbered vars set.
+
+ After maybe_create_global_var, we set pointers with the REF_ALL flag
+ to have alias sets that include all clobbered
+ memory tags and variables.
+
+ After this, memory partitioning is computed (by the function
+ compute_memory_partitions) and alias sets are reworked accordingly.
+
+ Lastly, we delete partitions with no symbols, and clean up after
+ ourselves. */
+
+/* Structure to map a variable to its alias set. */
+struct alias_map_d
+{
+ /* Variable and its alias set. */
+ tree var;
+ alias_set_type set;
+};
+
+
+/* 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, alias_set_type, tree, alias_set_type, bool);
+static tree create_memory_tag (tree type, bool is_type_tag);
+static tree get_smt_for (tree, struct alias_info *);
+static tree get_nmt_for (tree);
+static void 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 (void);
+static void set_pt_anything (tree);
+
+void debug_mp_info (VEC(mem_sym_stats_t,heap) *);
+
+static alloc_pool mem_sym_stats_pool;
+
+/* Return memory reference stats for symbol VAR. Create a new slot in
+ cfun->gimple_df->mem_sym_stats if needed. */
+
+static struct mem_sym_stats_d *
+get_mem_sym_stats_for (tree var)
+{
+ void **slot;
+ struct mem_sym_stats_d *stats;
+ struct pointer_map_t *map = gimple_mem_ref_stats (cfun)->mem_sym_stats;
+
+ gcc_assert (map);
+
+ slot = pointer_map_insert (map, var);
+ if (*slot == NULL)
+ {
+ stats = pool_alloc (mem_sym_stats_pool);
+ memset (stats, 0, sizeof (*stats));
+ stats->var = var;
+ *slot = (void *) stats;
+ }
+ else
+ stats = (struct mem_sym_stats_d *) *slot;
+
+ return stats;
+}
+
+
+/* Return memory reference statistics for variable VAR in function FN.
+ This is computed by alias analysis, but it is not kept
+ incrementally up-to-date. So, these stats are only accurate if
+ pass_may_alias has been run recently. If no alias information
+ exists, this function returns NULL. */
+
+static mem_sym_stats_t
+mem_sym_stats (struct function *fn, tree var)
+{
+ void **slot;
+ struct pointer_map_t *stats_map = gimple_mem_ref_stats (fn)->mem_sym_stats;
+
+ if (stats_map == NULL)
+ return NULL;
+
+ slot = pointer_map_contains (stats_map, var);
+ if (slot == NULL)
+ return NULL;
+
+ return (mem_sym_stats_t) *slot;
+}
+
+
+/* Set MPT to be the memory partition associated with symbol SYM. */
+
+static inline void
+set_memory_partition (tree sym, tree mpt)
+{
+#if defined ENABLE_CHECKING
+ if (mpt)
+ gcc_assert (TREE_CODE (mpt) == MEMORY_PARTITION_TAG
+ && !is_gimple_reg (sym));
+#endif
+
+ var_ann (sym)->mpt = mpt;
+ if (mpt)
+ {
+ if (MPT_SYMBOLS (mpt) == NULL)
+ MPT_SYMBOLS (mpt) = BITMAP_ALLOC (&alias_bitmap_obstack);
+
+ bitmap_set_bit (MPT_SYMBOLS (mpt), DECL_UID (sym));
+
+ /* MPT inherits the call-clobbering attributes from SYM. */
+ if (is_call_clobbered (sym))
+ {
+ MTAG_GLOBAL (mpt) = 1;
+ mark_call_clobbered (mpt, ESCAPE_IS_GLOBAL);
+ }
+ }
+}
+
+
+/* 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)
+ {
+ /* Note that it's possible for a symbol to have an associated
+ MPT and the MPT have a NULL empty set. During
+ init_alias_info, all MPTs get their sets cleared out, but the
+ symbols still point to the old MPTs that used to hold them.
+ This is done so that compute_memory_partitions can now which
+ symbols are losing or changing partitions and mark them for
+ renaming. */
+ if (MPT_SYMBOLS (mpt))
+ bitmap_clear_bit (MPT_SYMBOLS (mpt), DECL_UID (var));
+ set_memory_partition (var, NULL_TREE);
+ }
+}
+
+
+/* qsort comparison function to sort type/name tags by DECL_UID. */
+
+static int
+sort_tags_by_id (const void *pa, const void *pb)
+{
+ const_tree const a = *(const_tree const *)pa;
+ const_tree const b = *(const_tree const *)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,
+ bitmap on_worklist)
+{
+ 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);
+ bitmap_set_bit (on_worklist, DECL_UID (curr));
+ }
+ }
+}
+
+/* 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,
+ bitmap on_worklist)
+{
+ if (MTAG_P (alias) && !is_call_clobbered (alias)
+ && !bitmap_bit_p (on_worklist, DECL_UID (alias)))
+ {
+ VEC_safe_push (tree, heap, *worklist, alias);
+ VEC_safe_push (int, heap, *worklist2, reason);
+ bitmap_set_bit (on_worklist, DECL_UID (alias));
+ }
+}
+
+/* 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 on_worklist, bitmap queued)
+{
+ 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 you clobber one part of a structure, you
+ clobber the entire thing. While this does not make
+ the world a particularly nice place, it is necessary
+ in order to allow C/C++ tricks that involve
+ pointer arithmetic to work. */
+ if (TREE_CODE (entry) == STRUCT_FIELD_TAG)
+ bitmap_set_bit (queued, DECL_UID (SFT_PARENT_VAR (entry)));
+ else if (!unmodifiable_var_p (entry))
+ {
+ add_to_worklist (entry, worklist, worklist2, ta->escape_mask,
+ on_worklist);
+ mark_call_clobbered (entry, ta->escape_mask);
+ }
+ }
+ if (!bitmap_empty_p (queued))
+ {
+ EXECUTE_IF_SET_IN_BITMAP (queued, 0, i, bi)
+ {
+ subvar_t svars = get_subvars_for_var (referenced_var (i));
+ unsigned int i;
+ tree subvar;
+
+ for (i = 0; VEC_iterate (tree, svars, i, subvar); ++i)
+ if (!unmodifiable_var_p (subvar))
+ mark_call_clobbered (subvar, ta->escape_mask);
+ }
+ bitmap_clear (queued);
+ }
+}
+
+/* Tags containing global vars need to be marked as global.
+ 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;
+ bitmap queued;
+
+ /* Temporary bitmap to avoid quadratic behavior in marking
+ call clobbers. */
+ queued = BITMAP_ALLOC (&alias_bitmap_obstack);
+
+ 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)
+ {
+ tree alias = referenced_var (j);
+
+ /* If you clobber one part of a structure, you
+ clobber the entire thing. While this does not make
+ the world a particularly nice place, it is necessary
+ in order to allow C/C++ tricks that involve
+ pointer arithmetic to work. */
+ if (TREE_CODE (alias) == STRUCT_FIELD_TAG)
+ bitmap_set_bit (queued, DECL_UID (SFT_PARENT_VAR (alias)));
+ else if (!unmodifiable_var_p (alias))
+ mark_call_clobbered (alias, pi->escape_mask);
+ }
+ /* Process variables we need to clobber all parts of. */
+ if (!bitmap_empty_p (queued))
+ {
+ EXECUTE_IF_SET_IN_BITMAP (queued, 0, j, bi)
+ {
+ subvar_t svars = get_subvars_for_var (referenced_var (j));
+ unsigned int i;
+ tree subvar;
+
+ for (i = 0; VEC_iterate (tree, svars, i, subvar); ++i)
+ if (!unmodifiable_var_p (subvar))
+ mark_call_clobbered (subvar, pi->escape_mask);
+ }
+ bitmap_clear (queued);
+ }
+ }
+ }
+
+ /* 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;
+ }
+ }
+
+ BITMAP_FREE (queued);
+}
+
+/* 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;
+ bitmap on_worklist, queued;
+
+ timevar_push (TV_CALL_CLOBBER);
+ on_worklist = BITMAP_ALLOC (NULL);
+ queued = BITMAP_ALLOC (NULL);
+
+ set_initial_properties (ai);
+ init_transitive_clobber_worklist (&worklist, &worklist2, on_worklist);
+ while (VEC_length (tree, worklist) != 0)
+ {
+ tree curr = VEC_pop (tree, worklist);
+ int reason = VEC_pop (int, worklist2);
+
+ bitmap_clear_bit (on_worklist, DECL_UID (curr));
+ mark_call_clobbered (curr, reason);
+ mark_aliases_call_clobbered (curr, &worklist, &worklist2,
+ on_worklist, queued);
+ }
+ VEC_free (tree, heap, worklist);
+ VEC_free (int, heap, worklist2);
+ BITMAP_FREE (on_worklist);
+ BITMAP_FREE (queued);
+ compute_tag_properties ();
+ timevar_pop (TV_CALL_CLOBBER);
+}
+
+
+/* Dump memory partition information to FILE. */
+
+static void
+dump_memory_partitions (FILE *file)
+{
+ unsigned i, npart;
+ unsigned long nsyms;
+ tree mpt;
+
+ fprintf (file, "\nMemory partitions\n\n");
+ for (i = 0, npart = 0, nsyms = 0;
+ VEC_iterate (tree, gimple_ssa_operands (cfun)->mpt_table, i, mpt);
+ i++)
+ {
+ if (mpt)
+ {
+ bitmap syms = MPT_SYMBOLS (mpt);
+ unsigned long n = (syms) ? bitmap_count_bits (syms) : 0;
+
+ fprintf (file, "#%u: ", i);
+ print_generic_expr (file, mpt, 0);
+ fprintf (file, ": %lu elements: ", n);
+ dump_decl_set (file, syms);
+ npart++;
+ nsyms += n;
+ }
+ }
+
+ fprintf (file, "\n%u memory partitions holding %lu symbols\n", npart, nsyms);
+}
+
+
+/* Dump memory partition information to stderr. */
+
+void
+debug_memory_partitions (void)
+{
+ dump_memory_partitions (stderr);
+}
+
+
+/* Return true if memory partitioning is required given the memory
+ reference estimates in STATS. */
+
+static inline bool
+need_to_partition_p (struct mem_ref_stats_d *stats)
+{
+ long num_vops = stats->num_vuses + stats->num_vdefs;
+ long avg_vops = CEIL (num_vops, stats->num_mem_stmts);
+ return (num_vops > (long) MAX_ALIASED_VOPS
+ && avg_vops > (long) AVG_ALIASED_VOPS);
+}
+
+
+/* Count the actual number of virtual operators in CFUN. Note that
+ this is only meaningful after virtual operands have been populated,
+ so it should be invoked at the end of compute_may_aliases.
+
+ The number of virtual operators are stored in *NUM_VDEFS_P and
+ *NUM_VUSES_P, the number of partitioned symbols in
+ *NUM_PARTITIONED_P and the number of unpartitioned symbols in
+ *NUM_UNPARTITIONED_P.
+
+ If any of these pointers is NULL the corresponding count is not
+ computed. */
+
+static void
+count_mem_refs (long *num_vuses_p, long *num_vdefs_p,
+ long *num_partitioned_p, long *num_unpartitioned_p)
+{
+ block_stmt_iterator bsi;
+ basic_block bb;
+ long num_vdefs, num_vuses, num_partitioned, num_unpartitioned;
+ referenced_var_iterator rvi;
+ tree sym;
+
+ num_vuses = num_vdefs = num_partitioned = num_unpartitioned = 0;
+
+ if (num_vuses_p || num_vdefs_p)
+ FOR_EACH_BB (bb)
+ for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ {
+ tree stmt = bsi_stmt (bsi);
+ if (stmt_references_memory_p (stmt))
+ {
+ num_vuses += NUM_SSA_OPERANDS (stmt, SSA_OP_VUSE);
+ num_vdefs += NUM_SSA_OPERANDS (stmt, SSA_OP_VDEF);
+ }
+ }
+
+ if (num_partitioned_p || num_unpartitioned_p)
+ FOR_EACH_REFERENCED_VAR (sym, rvi)
+ {
+ if (is_gimple_reg (sym))
+ continue;
+
+ if (memory_partition (sym))
+ num_partitioned++;
+ else
+ num_unpartitioned++;
+ }
+
+ if (num_vdefs_p)
+ *num_vdefs_p = num_vdefs;
+
+ if (num_vuses_p)
+ *num_vuses_p = num_vuses;
+
+ if (num_partitioned_p)
+ *num_partitioned_p = num_partitioned;
+
+ if (num_unpartitioned_p)
+ *num_unpartitioned_p = num_unpartitioned;
+}
+
+
+/* The list is sorted by increasing partitioning score (PSCORE).
+ This score is computed such that symbols with high scores are
+ those that are least likely to be partitioned. Given a symbol
+ MP->VAR, PSCORE(S) is the result of the following weighted sum
+
+ PSCORE(S) = FW * 64 + FR * 32
+ + DW * 16 + DR * 8
+ + IW * 4 + IR * 2
+ + NO_ALIAS
+
+ where
+
+ FW Execution frequency of writes to S
+ FR Execution frequency of reads from S
+ DW Number of direct writes to S
+ DR Number of direct reads from S
+ IW Number of indirect writes to S
+ IR Number of indirect reads from S
+ NO_ALIAS State of the NO_ALIAS* flags
+
+ The basic idea here is that symbols that are frequently
+ written-to in hot paths of the code are the last to be considered
+ for partitioning. */
+
+static inline long
+mem_sym_score (mem_sym_stats_t mp)
+{
+ /* Unpartitionable SFTs are automatically thrown to the bottom of
+ the list. They are not stored in partitions, but they are used
+ for computing overall statistics. */
+ if (TREE_CODE (mp->var) == STRUCT_FIELD_TAG
+ && SFT_UNPARTITIONABLE_P (mp->var))
+ return LONG_MAX;
+
+ return mp->frequency_writes * 64 + mp->frequency_reads * 32
+ + mp->num_direct_writes * 16 + mp->num_direct_reads * 8
+ + mp->num_indirect_writes * 4 + mp->num_indirect_reads * 2
+ + var_ann (mp->var)->noalias_state;
+}
+
+
+/* Dump memory reference stats for function CFUN to FILE. */
+
+void
+dump_mem_ref_stats (FILE *file)
+{
+ long actual_num_vuses, actual_num_vdefs;
+ long num_partitioned, num_unpartitioned;
+ struct mem_ref_stats_d *stats;
+
+ stats = gimple_mem_ref_stats (cfun);
+
+ count_mem_refs (&actual_num_vuses, &actual_num_vdefs, &num_partitioned,
+ &num_unpartitioned);
+
+ fprintf (file, "\nMemory reference statistics for %s\n\n",
+ lang_hooks.decl_printable_name (current_function_decl, 2));
+
+ fprintf (file, "Number of memory statements: %ld\n",
+ stats->num_mem_stmts);
+ fprintf (file, "Number of call sites: %ld\n",
+ stats->num_call_sites);
+ fprintf (file, "Number of pure/const call sites: %ld\n",
+ stats->num_pure_const_call_sites);
+ fprintf (file, "Number of asm sites: %ld\n",
+ stats->num_asm_sites);
+ fprintf (file, "Estimated number of loads: %ld (%ld/stmt)\n",
+ stats->num_vuses,
+ (stats->num_mem_stmts)
+ ? CEIL (stats->num_vuses, stats->num_mem_stmts)
+ : 0);
+ fprintf (file, "Actual number of loads: %ld (%ld/stmt)\n",
+ actual_num_vuses,
+ (stats->num_mem_stmts)
+ ? CEIL (actual_num_vuses, stats->num_mem_stmts)
+ : 0);
+
+ if (actual_num_vuses > stats->num_vuses + (stats->num_vuses / 25))
+ fprintf (file, "\t(warning: estimation is lower by more than 25%%)\n");
+
+ fprintf (file, "Estimated number of stores: %ld (%ld/stmt)\n",
+ stats->num_vdefs,
+ (stats->num_mem_stmts)
+ ? CEIL (stats->num_vdefs, stats->num_mem_stmts)
+ : 0);
+ fprintf (file, "Actual number of stores: %ld (%ld/stmt)\n",
+ actual_num_vdefs,
+ (stats->num_mem_stmts)
+ ? CEIL (actual_num_vdefs, stats->num_mem_stmts)
+ : 0);
+
+ if (actual_num_vdefs > stats->num_vdefs + (stats->num_vdefs / 25))
+ fprintf (file, "\t(warning: estimation is lower by more than 25%%)\n");
+
+ fprintf (file, "Partitioning thresholds: MAX = %d AVG = %d "
+ "(%sNEED TO PARTITION)\n", MAX_ALIASED_VOPS, AVG_ALIASED_VOPS,
+ stats->num_mem_stmts && need_to_partition_p (stats) ? "" : "NO ");
+ fprintf (file, "Number of partitioned symbols: %ld\n", num_partitioned);
+ fprintf (file, "Number of unpartitioned symbols: %ld\n", num_unpartitioned);
+}
+
+
+/* Dump memory reference stats for function FN to stderr. */
+
+void
+debug_mem_ref_stats (void)
+{
+ dump_mem_ref_stats (stderr);
+}
+
+
+/* Dump memory reference stats for variable VAR to FILE. */
+
+static void
+dump_mem_sym_stats (FILE *file, tree var)
+{
+ mem_sym_stats_t stats = mem_sym_stats (cfun, var);
+
+ if (stats == NULL)
+ return;
+
+ fprintf (file, "read frequency: %6ld, write frequency: %6ld, "
+ "direct reads: %3ld, direct writes: %3ld, "
+ "indirect reads: %4ld, indirect writes: %4ld, symbol: ",
+ stats->frequency_reads, stats->frequency_writes,
+ stats->num_direct_reads, stats->num_direct_writes,
+ stats->num_indirect_reads, stats->num_indirect_writes);
+ print_generic_expr (file, stats->var, 0);
+ fprintf (file, ", tags: ");
+ dump_decl_set (file, stats->parent_tags);
+}
+
+
+/* Dump memory reference stats for variable VAR to stderr. */
+
+void
+debug_mem_sym_stats (tree var)
+{
+ dump_mem_sym_stats (stderr, var);
+}
+
+/* Dump memory reference stats for variable VAR to FILE. For use
+ of tree-dfa.c:dump_variable. */
+
+void
+dump_mem_sym_stats_for_var (FILE *file, tree var)
+{
+ mem_sym_stats_t stats = mem_sym_stats (cfun, var);
+
+ if (stats == NULL)
+ return;
+
+ fprintf (file, ", score: %ld", mem_sym_score (stats));
+ fprintf (file, ", direct reads: %ld", stats->num_direct_reads);
+ fprintf (file, ", direct writes: %ld", stats->num_direct_writes);
+ fprintf (file, ", indirect reads: %ld", stats->num_indirect_reads);
+ fprintf (file, ", indirect writes: %ld", stats->num_indirect_writes);
+}
+
+/* Dump memory reference stats for all memory symbols to FILE. */
+
+static void
+dump_all_mem_sym_stats (FILE *file)
+{
+ referenced_var_iterator rvi;
+ tree sym;
+
+ FOR_EACH_REFERENCED_VAR (sym, rvi)
+ {
+ if (is_gimple_reg (sym))
+ continue;
+
+ dump_mem_sym_stats (file, sym);
+ }
+}
-/* 'true' after aliases have been computed (see compute_may_aliases). */
-bool aliases_computed_p;
-/* Structure to map a variable to its alias set and keep track of the
- virtual operands that will be needed to represent it. */
-struct alias_map_d
+/* Dump memory reference stats for all memory symbols to stderr. */
+
+void
+debug_all_mem_sym_stats (void)
+{
+ dump_all_mem_sym_stats (stderr);
+}
+
+
+/* Dump the MP_INFO array to FILE. */
+
+static void
+dump_mp_info (FILE *file, VEC(mem_sym_stats_t,heap) *mp_info)
+{
+ unsigned i;
+ mem_sym_stats_t mp_p;
+
+ for (i = 0; VEC_iterate (mem_sym_stats_t, mp_info, i, mp_p); i++)
+ if (!mp_p->partitioned_p)
+ dump_mem_sym_stats (file, mp_p->var);
+}
+
+
+/* Dump the MP_INFO array to stderr. */
+
+void
+debug_mp_info (VEC(mem_sym_stats_t,heap) *mp_info)
+{
+ dump_mp_info (stderr, mp_info);
+}
+
+
+/* Update memory reference stats for symbol VAR in statement STMT.
+ NUM_DIRECT_READS and NUM_DIRECT_WRITES specify the number of times
+ that VAR is read/written in STMT (indirect reads/writes are not
+ recorded by this function, see compute_memory_partitions). */
+
+void
+update_mem_sym_stats_from_stmt (tree var, tree stmt, long num_direct_reads,
+ long num_direct_writes)
+{
+ mem_sym_stats_t stats;
+
+ gcc_assert (num_direct_reads >= 0 && num_direct_writes >= 0);
+
+ stats = get_mem_sym_stats_for (var);
+
+ stats->num_direct_reads += num_direct_reads;
+ stats->frequency_reads += ((long) bb_for_stmt (stmt)->frequency
+ * num_direct_reads);
+
+ stats->num_direct_writes += num_direct_writes;
+ stats->frequency_writes += ((long) bb_for_stmt (stmt)->frequency
+ * num_direct_writes);
+}
+
+
+/* Given two MP_INFO entries MP1 and MP2, return -1 if MP1->VAR should
+ be partitioned before MP2->VAR, 0 if they are the same or 1 if
+ MP1->VAR should be partitioned after MP2->VAR. */
+
+static inline int
+compare_mp_info_entries (mem_sym_stats_t mp1, mem_sym_stats_t mp2)
+{
+ long pscore1 = mem_sym_score (mp1);
+ long pscore2 = mem_sym_score (mp2);
+
+ if (pscore1 < pscore2)
+ return -1;
+ else if (pscore1 > pscore2)
+ return 1;
+ else
+ return DECL_UID (mp1->var) - DECL_UID (mp2->var);
+}
+
+
+/* Comparison routine for qsort. The list is sorted by increasing
+ partitioning score (PSCORE). This score is computed such that
+ symbols with high scores are those that are least likely to be
+ partitioned. */
+
+static int
+mp_info_cmp (const void *p, const void *q)
+{
+ mem_sym_stats_t e1 = *((const mem_sym_stats_t *) p);
+ mem_sym_stats_t e2 = *((const mem_sym_stats_t *) q);
+ return compare_mp_info_entries (e1, e2);
+}
+
+
+/* Sort the array of reference counts used to compute memory partitions.
+ Elements are sorted in ascending order of execution frequency and
+ descending order of virtual operators needed. */
+
+static inline void
+sort_mp_info (VEC(mem_sym_stats_t,heap) *list)
+{
+ unsigned num = VEC_length (mem_sym_stats_t, list);
+
+ if (num < 2)
+ return;
+
+ if (num == 2)
+ {
+ if (compare_mp_info_entries (VEC_index (mem_sym_stats_t, list, 0),
+ VEC_index (mem_sym_stats_t, list, 1)) > 0)
+ {
+ /* Swap elements if they are in the wrong order. */
+ mem_sym_stats_t tmp = VEC_index (mem_sym_stats_t, list, 0);
+ VEC_replace (mem_sym_stats_t, list, 0,
+ VEC_index (mem_sym_stats_t, list, 1));
+ VEC_replace (mem_sym_stats_t, list, 1, tmp);
+ }
+
+ return;
+ }
+
+ /* There are 3 or more elements, call qsort. */
+ qsort (VEC_address (mem_sym_stats_t, list),
+ VEC_length (mem_sym_stats_t, list),
+ sizeof (mem_sym_stats_t),
+ mp_info_cmp);
+}
+
+
+/* Return the memory partition tag (MPT) associated with memory
+ symbol SYM. */
+
+static tree
+get_mpt_for (tree sym)
+{
+ tree mpt;
+
+ /* Don't create a new tag unnecessarily. */
+ mpt = memory_partition (sym);
+ if (mpt == NULL_TREE)
+ {
+ mpt = create_tag_raw (MEMORY_PARTITION_TAG, TREE_TYPE (sym), "MPT");
+ TREE_ADDRESSABLE (mpt) = 0;
+ add_referenced_var (mpt);
+ VEC_safe_push (tree, heap, gimple_ssa_operands (cfun)->mpt_table, mpt);
+ gcc_assert (MPT_SYMBOLS (mpt) == NULL);
+ set_memory_partition (sym, mpt);
+ }
+
+ return mpt;
+}
+
+
+/* Add MP_P->VAR to a memory partition and return the partition. */
+
+static tree
+find_partition_for (mem_sym_stats_t mp_p)
+{
+ unsigned i;
+ VEC(tree,heap) *mpt_table;
+ tree mpt;
+
+ mpt_table = gimple_ssa_operands (cfun)->mpt_table;
+ mpt = NULL_TREE;
+
+ /* Find an existing partition for MP_P->VAR. */
+ for (i = 0; VEC_iterate (tree, mpt_table, i, mpt); i++)
+ {
+ mem_sym_stats_t mpt_stats;
+
+ /* If MPT does not have any symbols yet, use it. */
+ if (MPT_SYMBOLS (mpt) == NULL)
+ break;
+
+ /* Otherwise, see if MPT has common parent tags with MP_P->VAR,
+ but avoid grouping clobbered variables with non-clobbered
+ variables (otherwise, this tends to creates a single memory
+ partition because other call-clobbered variables may have
+ common parent tags with non-clobbered ones). */
+ mpt_stats = get_mem_sym_stats_for (mpt);
+ if (mp_p->parent_tags
+ && mpt_stats->parent_tags
+ && is_call_clobbered (mpt) == is_call_clobbered (mp_p->var)
+ && bitmap_intersect_p (mpt_stats->parent_tags, mp_p->parent_tags))
+ break;
+
+ /* If no common parent tags are found, see if both MPT and
+ MP_P->VAR are call-clobbered. */
+ if (is_call_clobbered (mpt) && is_call_clobbered (mp_p->var))
+ break;
+ }
+
+ if (mpt == NULL_TREE)
+ mpt = get_mpt_for (mp_p->var);
+ else
+ set_memory_partition (mp_p->var, mpt);
+
+ mp_p->partitioned_p = true;
+
+ mark_sym_for_renaming (mp_p->var);
+ mark_sym_for_renaming (mpt);
+
+ return mpt;
+}
+
+
+/* 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;
+
+ 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);
+}
+
+
+/* Determine how many virtual operands can be saved by partitioning
+ MP_P->VAR into MPT. When a symbol S is thrown inside a partition
+ P, every virtual operand that used to reference S will now
+ reference P. Whether it reduces the number of virtual operands
+ depends on:
+
+ 1- Direct references to S are never saved. Instead of the virtual
+ operand to S, we will now have a virtual operand to P.
+
+ 2- Indirect references to S are reduced only for those memory tags
+ holding S that already had other symbols partitioned into P.
+ For instance, if a memory tag T has the alias set { a b S c },
+ the first time we partition S into P, the alias set will become
+ { a b P c }, so no virtual operands will be saved. However, if
+ we now partition symbol 'c' into P, then the alias set for T
+ will become { a b P }, so we will be saving one virtual operand
+ for every indirect reference to 'c'.
+
+ 3- Is S is call-clobbered, we save as many virtual operands as
+ call/asm sites exist in the code, but only if other
+ call-clobbered symbols have been grouped into P. The first
+ call-clobbered symbol that we group does not produce any
+ savings.
+
+ MEM_REF_STATS points to CFUN's memory reference information. */
+
+static void
+estimate_vop_reduction (struct mem_ref_stats_d *mem_ref_stats,
+ mem_sym_stats_t mp_p, tree mpt)
+{
+ unsigned i;
+ bitmap_iterator bi;
+ mem_sym_stats_t mpt_stats;
+
+ /* We should only get symbols with indirect references here. */
+ gcc_assert (mp_p->num_indirect_reads > 0 || mp_p->num_indirect_writes > 0);
+
+ /* Note that the only statistics we keep for MPT is the set of
+ parent tags to know which memory tags have had alias members
+ partitioned, and the indicator has_call_clobbered_vars.
+ Reference counts are not important for MPT. */
+ mpt_stats = get_mem_sym_stats_for (mpt);
+
+ /* Traverse all the parent tags for MP_P->VAR. For every tag T, if
+ partition P is already grouping aliases of T, then reduce the
+ number of virtual operands by the number of direct references
+ to T. */
+ if (mp_p->parent_tags)
+ {
+ if (mpt_stats->parent_tags == NULL)
+ mpt_stats->parent_tags = BITMAP_ALLOC (&alias_bitmap_obstack);
+
+ EXECUTE_IF_SET_IN_BITMAP (mp_p->parent_tags, 0, i, bi)
+ {
+ if (bitmap_bit_p (mpt_stats->parent_tags, i))
+ {
+ /* Partition MPT is already partitioning symbols in the
+ alias set for TAG. This means that we are now saving
+ 1 virtual operand for every direct reference to TAG. */
+ tree tag = referenced_var (i);
+ mem_sym_stats_t tag_stats = mem_sym_stats (cfun, tag);
+ mem_ref_stats->num_vuses -= tag_stats->num_direct_reads;
+ mem_ref_stats->num_vdefs -= tag_stats->num_direct_writes;
+ }
+ else
+ {
+ /* This is the first symbol in tag I's alias set that is
+ being grouped under MPT. We will not save any
+ virtual operands this time, but record that MPT is
+ grouping a symbol from TAG's alias set so that the
+ next time we get the savings. */
+ bitmap_set_bit (mpt_stats->parent_tags, i);
+ }
+ }
+ }
+
+ /* If MP_P->VAR is call-clobbered, and MPT is already grouping
+ call-clobbered symbols, then we will save as many virtual
+ operands as asm/call sites there are. */
+ if (is_call_clobbered (mp_p->var))
+ {
+ if (mpt_stats->has_call_clobbered_vars)
+ mem_ref_stats->num_vdefs -= mem_ref_stats->num_call_sites
+ + mem_ref_stats->num_asm_sites;
+ else
+ mpt_stats->has_call_clobbered_vars = true;
+ }
+}
+
+
+/* Helper for compute_memory_partitions. Transfer reference counts
+ from pointers to their pointed-to sets. Counters for pointers were
+ computed by update_alias_info. MEM_REF_STATS points to CFUN's
+ memory reference information. */
+
+static void
+update_reference_counts (struct mem_ref_stats_d *mem_ref_stats)
+{
+ unsigned i;
+ bitmap_iterator bi;
+ mem_sym_stats_t sym_stats;
+
+ for (i = 1; i < num_ssa_names; i++)
+ {
+ tree ptr;
+ struct ptr_info_def *pi;
+
+ ptr = ssa_name (i);
+ if (ptr
+ && POINTER_TYPE_P (TREE_TYPE (ptr))
+ && (pi = SSA_NAME_PTR_INFO (ptr)) != NULL
+ && pi->is_dereferenced)
+ {
+ unsigned j;
+ bitmap_iterator bj;
+ tree tag;
+ mem_sym_stats_t ptr_stats, tag_stats;
+
+ /* If PTR has flow-sensitive points-to information, use
+ PTR's name tag, otherwise use the symbol tag associated
+ with PTR's symbol. */
+ if (pi->name_mem_tag)
+ tag = pi->name_mem_tag;
+ else
+ tag = symbol_mem_tag (SSA_NAME_VAR (ptr));
+
+ ptr_stats = get_mem_sym_stats_for (ptr);
+ tag_stats = get_mem_sym_stats_for (tag);
+
+ /* TAG has as many direct references as dereferences we
+ found for its parent pointer. */
+ tag_stats->num_direct_reads += ptr_stats->num_direct_reads;
+ tag_stats->num_direct_writes += ptr_stats->num_direct_writes;
+
+ /* All the dereferences of pointer PTR are considered direct
+ references to PTR's memory tag (TAG). In turn,
+ references to TAG will become virtual operands for every
+ symbol in TAG's alias set. So, for every symbol ALIAS in
+ TAG's alias set, add as many indirect references to ALIAS
+ as direct references there are for TAG. */
+ if (MTAG_ALIASES (tag))
+ EXECUTE_IF_SET_IN_BITMAP (MTAG_ALIASES (tag), 0, j, bj)
+ {
+ tree alias = referenced_var (j);
+ sym_stats = get_mem_sym_stats_for (alias);
+
+ /* All the direct references to TAG are indirect references
+ to ALIAS. */
+ sym_stats->num_indirect_reads += ptr_stats->num_direct_reads;
+ sym_stats->num_indirect_writes += ptr_stats->num_direct_writes;
+ sym_stats->frequency_reads += ptr_stats->frequency_reads;
+ sym_stats->frequency_writes += ptr_stats->frequency_writes;
+
+ /* Indicate that TAG is one of ALIAS's parent tags. */
+ if (sym_stats->parent_tags == NULL)
+ sym_stats->parent_tags = BITMAP_ALLOC (&alias_bitmap_obstack);
+ bitmap_set_bit (sym_stats->parent_tags, DECL_UID (tag));
+ }
+ }
+ }
+
+ /* Call-clobbered symbols are indirectly written at every
+ call/asm site. */
+ EXECUTE_IF_SET_IN_BITMAP (gimple_call_clobbered_vars (cfun), 0, i, bi)
+ {
+ tree sym = referenced_var (i);
+ sym_stats = get_mem_sym_stats_for (sym);
+ sym_stats->num_indirect_writes += mem_ref_stats->num_call_sites
+ + mem_ref_stats->num_asm_sites;
+ }
+
+ /* Addressable symbols are indirectly written at some ASM sites.
+ Since only ASM sites that clobber memory actually affect
+ addressable symbols, this is an over-estimation. */
+ EXECUTE_IF_SET_IN_BITMAP (gimple_addressable_vars (cfun), 0, i, bi)
+ {
+ tree sym = referenced_var (i);
+ sym_stats = get_mem_sym_stats_for (sym);
+ sym_stats->num_indirect_writes += mem_ref_stats->num_asm_sites;
+ }
+}
+
+
+/* Helper for compute_memory_partitions. Add all memory symbols to
+ *MP_INFO_P and compute the initial estimate for the total number of
+ virtual operands needed. MEM_REF_STATS points to CFUN's memory
+ reference information. On exit, *TAGS_P will contain the list of
+ memory tags whose alias set need to be rewritten after
+ partitioning. */
+
+static void
+build_mp_info (struct mem_ref_stats_d *mem_ref_stats,
+ VEC(mem_sym_stats_t,heap) **mp_info_p,
+ VEC(tree,heap) **tags_p)
{
- /* Variable and its alias set. */
tree var;
- HOST_WIDE_INT set;
+ referenced_var_iterator rvi;
- /* Total number of virtual operands that will be needed to represent
- all the aliases of VAR. */
- long total_alias_vops;
+ FOR_EACH_REFERENCED_VAR (var, rvi)
+ {
+ mem_sym_stats_t sym_stats;
+ tree old_mpt;
- /* Nonzero if the aliases for this memory tag have been grouped
- already. Used in group_aliases. */
- unsigned int grouped_p : 1;
+ /* We are only interested in memory symbols other than MPTs. */
+ if (is_gimple_reg (var) || TREE_CODE (var) == MEMORY_PARTITION_TAG)
+ continue;
- /* Set of variables aliased with VAR. This is the exact same
- information contained in VAR_ANN (VAR)->MAY_ALIASES, but in
- bitmap form to speed up alias grouping. */
- bitmap may_aliases;
-};
+ /* Collect memory tags into the TAGS array so that we can
+ rewrite their alias sets after partitioning. */
+ if (MTAG_P (var) && MTAG_ALIASES (var))
+ VEC_safe_push (tree, heap, *tags_p, var);
+ /* Since we are going to re-compute partitions, any symbols that
+ used to belong to a partition must be detached from it and
+ marked for renaming. */
+ if ((old_mpt = memory_partition (var)) != NULL)
+ {
+ mark_sym_for_renaming (old_mpt);
+ set_memory_partition (var, NULL_TREE);
+ mark_sym_for_renaming (var);
+ }
-/* Counters used to display statistics on alias analysis. */
-struct alias_stats_d
+ sym_stats = get_mem_sym_stats_for (var);
+
+ /* Add VAR's reference info to MP_INFO. Note that the only
+ symbols that make sense to partition are those that have
+ indirect references. If a symbol S is always directly
+ referenced, partitioning it will not reduce the number of
+ virtual operators. The only symbols that are profitable to
+ partition are those that belong to alias sets and/or are
+ call-clobbered. */
+ if (sym_stats->num_indirect_reads > 0
+ || sym_stats->num_indirect_writes > 0)
+ VEC_safe_push (mem_sym_stats_t, heap, *mp_info_p, sym_stats);
+
+ /* Update the number of estimated VOPS. Note that direct
+ references to memory tags are always counted as indirect
+ references to their alias set members, so if a memory tag has
+ aliases, do not count its direct references to avoid double
+ accounting. */
+ if (!MTAG_P (var) || !MTAG_ALIASES (var))
+ {
+ mem_ref_stats->num_vuses += sym_stats->num_direct_reads;
+ mem_ref_stats->num_vdefs += sym_stats->num_direct_writes;
+ }
+
+ mem_ref_stats->num_vuses += sym_stats->num_indirect_reads;
+ mem_ref_stats->num_vdefs += sym_stats->num_indirect_writes;
+ }
+}
+
+
+/* Compute memory partitions. A memory partition (MPT) is an
+ arbitrary grouping of memory symbols, such that references to one
+ member of the group is considered a reference to all the members of
+ the group.
+
+ As opposed to alias sets in memory tags, the grouping into
+ partitions is completely arbitrary and only done to reduce the
+ number of virtual operands. The only rule that needs to be
+ observed when creating memory partitions is that given two memory
+ partitions MPT.i and MPT.j, they must not contain symbols in
+ common.
+
+ Memory partitions are used when putting the program into Memory-SSA
+ form. In particular, in Memory-SSA PHI nodes are not computed for
+ individual memory symbols. They are computed for memory
+ partitions. This reduces the amount of PHI nodes in the SSA graph
+ at the expense of precision (i.e., it makes unrelated stores affect
+ each other).
+
+ However, it is possible to increase precision by changing this
+ partitioning scheme. For instance, if the partitioning scheme is
+ such that get_mpt_for is the identity function (that is,
+ get_mpt_for (s) = s), this will result in ultimate precision at the
+ expense of huge SSA webs.
+
+ At the other extreme, a partitioning scheme that groups all the
+ symbols in the same set results in minimal SSA webs and almost
+ total loss of precision.
+
+ There partitioning heuristic uses three parameters to decide the
+ order in which symbols are processed. The list of symbols is
+ sorted so that symbols that are more likely to be partitioned are
+ near the top of the list:
+
+ - Execution frequency. If a memory references is in a frequently
+ executed code path, grouping it into a partition may block useful
+ transformations and cause sub-optimal code generation. So, the
+ partition heuristic tries to avoid grouping symbols with high
+ execution frequency scores. Execution frequency is taken
+ directly from the basic blocks where every reference is made (see
+ update_mem_sym_stats_from_stmt), which in turn uses the
+ profile guided machinery, so if the program is compiled with PGO
+ enabled, more accurate partitioning decisions will be made.
+
+ - Number of references. Symbols with few references in the code,
+ are partitioned before symbols with many references.
+
+ - NO_ALIAS attributes. Symbols with any of the NO_ALIAS*
+ attributes are partitioned after symbols marked MAY_ALIAS.
+
+ Once the list is sorted, the partitioning proceeds as follows:
+
+ 1- For every symbol S in MP_INFO, create a new memory partition MP,
+ if necessary. To avoid memory partitions that contain symbols
+ from non-conflicting alias sets, memory partitions are
+ associated to the memory tag that holds S in its alias set. So,
+ when looking for a memory partition for S, the memory partition
+ associated with one of the memory tags holding S is chosen. If
+ none exists, a new one is created.
+
+ 2- Add S to memory partition MP.
+
+ 3- Reduce by 1 the number of VOPS for every memory tag holding S.
+
+ 4- If the total number of VOPS is less than MAX_ALIASED_VOPS or the
+ average number of VOPS per statement is less than
+ AVG_ALIASED_VOPS, stop. Otherwise, go to the next symbol in the
+ list. */
+
+static void
+compute_memory_partitions (void)
{
- 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;
-};
+ tree tag;
+ unsigned i;
+ mem_sym_stats_t mp_p;
+ VEC(mem_sym_stats_t,heap) *mp_info;
+ bitmap new_aliases;
+ VEC(tree,heap) *tags;
+ struct mem_ref_stats_d *mem_ref_stats;
+ int prev_max_aliased_vops;
+
+ mem_ref_stats = gimple_mem_ref_stats (cfun);
+ gcc_assert (mem_ref_stats->num_vuses == 0 && mem_ref_stats->num_vdefs == 0);
+
+ if (mem_ref_stats->num_mem_stmts == 0)
+ return;
+ timevar_push (TV_MEMORY_PARTITIONING);
-/* Local variables. */
-static struct alias_stats_d alias_stats;
+ mp_info = NULL;
+ tags = NULL;
+ prev_max_aliased_vops = MAX_ALIASED_VOPS;
-/* Local functions. */
-static void compute_flow_insensitive_aliasing (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_tmt_for (tree, struct alias_info *);
-static tree get_nmt_for (tree);
-static void add_may_alias (tree, tree);
-static void replace_may_alias (tree, size_t, 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 group_aliases (struct alias_info *);
-static void set_pt_anything (tree ptr);
+ /* Since we clearly cannot lower the number of virtual operators
+ below the total number of memory statements in the function, we
+ may need to adjust MAX_ALIASED_VOPS beforehand. */
+ if (MAX_ALIASED_VOPS < mem_ref_stats->num_mem_stmts)
+ MAX_ALIASED_VOPS = mem_ref_stats->num_mem_stmts;
+
+ /* Update reference stats for all the pointed-to variables and
+ memory tags. */
+ update_reference_counts (mem_ref_stats);
+
+ /* Add all the memory symbols to MP_INFO. */
+ build_mp_info (mem_ref_stats, &mp_info, &tags);
+
+ /* No partitions required if we are below the threshold. */
+ if (!need_to_partition_p (mem_ref_stats))
+ {
+ if (dump_file)
+ fprintf (dump_file, "\nMemory partitioning NOT NEEDED for %s\n",
+ get_name (current_function_decl));
+ goto done;
+ }
+
+ /* Sort the MP_INFO array so that symbols that should be partitioned
+ first are near the top of the list. */
+ sort_mp_info (mp_info);
+
+ if (dump_file)
+ {
+ fprintf (dump_file, "\nMemory partitioning NEEDED for %s\n\n",
+ get_name (current_function_decl));
+ fprintf (dump_file, "Memory symbol references before partitioning:\n");
+ dump_mp_info (dump_file, mp_info);
+ }
+
+ /* Create partitions for variables in MP_INFO until we have enough
+ to lower the total number of VOPS below MAX_ALIASED_VOPS or if
+ the average number of VOPS per statement is below
+ AVG_ALIASED_VOPS. */
+ for (i = 0; VEC_iterate (mem_sym_stats_t, mp_info, i, mp_p); i++)
+ {
+ tree mpt;
+
+ /* If we are below the threshold, stop. */
+ if (!need_to_partition_p (mem_ref_stats))
+ break;
+
+ /* SFTs that are marked unpartitionable should not be added to
+ partitions. These SFTs are special because they mark the
+ first SFT into a structure where a pointer is pointing to.
+ This is needed by the operand scanner to find adjacent
+ fields. See add_vars_for_offset for details. */
+ if (TREE_CODE (mp_p->var) == STRUCT_FIELD_TAG
+ && SFT_UNPARTITIONABLE_P (mp_p->var))
+ continue;
+
+ mpt = find_partition_for (mp_p);
+ estimate_vop_reduction (mem_ref_stats, mp_p, mpt);
+ }
+
+ /* After partitions have been created, rewrite alias sets to use
+ them instead of the original symbols. This way, if the alias set
+ was computed as { a b c d e f }, and the subset { b e f } was
+ grouped into partition MPT.3, then the new alias set for the tag
+ will be { a c d MPT.3 }.
+
+ Note that this is not strictly necessary. The operand scanner
+ will always check if a symbol belongs to a partition when adding
+ virtual operands. However, by reducing the size of the alias
+ sets to be scanned, the work needed inside the operand scanner is
+ significantly reduced. */
+ new_aliases = BITMAP_ALLOC (&alias_bitmap_obstack);
+
+ for (i = 0; VEC_iterate (tree, tags, i, tag); i++)
+ {
+ rewrite_alias_set_for (tag, new_aliases);
+ bitmap_clear (new_aliases);
+ }
-/* Global declarations. */
+ BITMAP_FREE (new_aliases);
-/* Call clobbered variables in the function. If bit I is set, then
- REFERENCED_VARS (I) is call-clobbered. */
-bitmap call_clobbered_vars;
+ if (dump_file)
+ {
+ fprintf (dump_file, "\nMemory symbol references after partitioning:\n");
+ dump_mp_info (dump_file, mp_info);
+ }
+
+done:
+ /* Free allocated memory. */
+ VEC_free (mem_sym_stats_t, heap, mp_info);
+ VEC_free (tree, heap, tags);
-/* Addressable variables in the function. If bit I is set, then
- REFERENCED_VARS (I) has had its address taken. Note that
- CALL_CLOBBERED_VARS and ADDRESSABLE_VARS are not related. An
- addressable variable is not necessarily call-clobbered (e.g., a
- local addressable whose address does not escape) and not all
- call-clobbered variables are addressable (e.g., a local static
- variable). */
-bitmap addressable_vars;
+ MAX_ALIASED_VOPS = prev_max_aliased_vops;
-/* When the program has too many call-clobbered variables and call-sites,
- this variable is used to represent the clobbering effects of function
- calls. In these cases, all the call clobbered variables in the program
- are forced to alias this variable. This reduces compile times by not
- having to keep track of too many V_MAY_DEF expressions at call sites. */
-tree global_var;
+ timevar_pop (TV_MEMORY_PARTITIONING);
+}
/* Compute may-alias information for every variable referenced in function
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 "type memory tag" (TMT). The other class are those associated
+ 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 type
+ 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
3- Compute flow-insensitive aliases
- This pass will compare the alias set of every type memory tag and every
- addressable variable found in the program. Given a type memory tag TMT
- and an addressable variable V. If the alias sets of TMT and V conflict
- (as computed by may_alias_p), then V is marked as an alias tag and added
- to the alias set of TMT.
+ 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:
return *p;
}
- After aliasing analysis has finished, the type memory tag for pointer
+ 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'.
p_6 = &b;
# p_1 = PHI <p_4(1), p_6(2)>;
- # a_7 = V
_MAY_DEF <a_3>;
- # b_8 = V_MAY_DEF <b_5>;
+ # a_7 = VDEF <a_3>;
+ # b_8 = VDEF <b_5>;
*p_1 = 3;
- # a_9 = V
_MAY_DEF <a_7>
+ # a_9 = VDEF <a_7>
# VUSE <b_8>
a_9 = b_8 + 2;
compilation time.
When the number of virtual operands needed to represent aliased
- loads and stores grows too large (configurable with @option{--param
- max-aliased-vops}), alias sets are grouped to avoid severe
- compile-time slow downs and memory consumption. See group_aliases. */
+ loads and stores grows too large (configurable with option --param
+ max-aliased-vops and --param avg-aliased-vops), alias sets are
+ grouped to avoid severe compile-time slow downs and memory
+ consumption. See compute_memory_partitions. */
-static void
+unsigned int
compute_may_aliases (void)
{
struct alias_info *ai;
+
+ timevar_push (TV_TREE_MAY_ALIAS);
memset (&alias_stats, 0, sizeof (alias_stats));
not needed anymore. */
setup_pointers_and_addressables (ai);
- /* Compute flow-sensitive, points-to based aliasing for all the name
- memory tags. Note that this pass needs to be done before flow
- insensitive analysis because it uses the points-to information
- gathered before to mark call-clobbered type tags. */
- compute_flow_sensitive_aliasing (ai);
-
/* Compute type-based flow-insensitive aliasing for all the type
memory tags. */
compute_flow_insensitive_aliasing (ai);
- /* If the program has too many call-clobbered variables and/or function
- calls, create .GLOBAL_VAR and use it to model call-clobbering
- semantics at call sites. This reduces the number of virtual operands
- considerably, improving compile times at the expense of lost
- aliasing precision. */
- maybe_create_global_var (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 ();
+
+ /* 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 ();
+
+ /* Remove partitions with no symbols. Partitions may end up with an
+ empty MPT_SYMBOLS set if a previous round of alias analysis
+ needed to partition more symbols. Since we don't need those
+ partitions anymore, remove them to free up the space. */
+ {
+ tree mpt;
+ unsigned i;
+ VEC(tree,heap) *mpt_table;
+
+ mpt_table = gimple_ssa_operands (cfun)->mpt_table;
+ i = 0;
+ while (i < VEC_length (tree, mpt_table))
+ {
+ mpt = VEC_index (tree, mpt_table, i);
+ if (MPT_SYMBOLS (mpt) == NULL)
+ VEC_unordered_remove (tree, mpt_table, i);
+ else
+ i++;
+ }
+ }
+
+ /* Populate all virtual operands and newly promoted register operands. */
+ {
+ block_stmt_iterator bsi;
+ basic_block bb;
+ FOR_EACH_BB (bb)
+ for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ update_stmt_if_modified (bsi_stmt (bsi));
+ }
/* Debugging dumps. */
if (dump_file)
{
- dump_referenced_vars (dump_file);
- if (dump_flags & TDF_STATS)
- dump_alias_stats (dump_file);
- dump_points_to_info (dump_file);
+ dump_mem_ref_stats (dump_file);
dump_alias_info (dump_file);
+ dump_points_to_info (dump_file);
+
+ if (dump_flags & TDF_STATS)
+ dump_alias_stats (dump_file);
+
+ if (dump_flags & TDF_DETAILS)
+ dump_referenced_vars (dump_file);
}
+ /* Report strict aliasing violations. */
+ strict_aliasing_warning_backend ();
+
/* Deallocate memory used by aliasing data structures. */
delete_alias_info (ai);
- {
- block_stmt_iterator bsi;
- basic_block bb;
- FOR_EACH_BB (bb)
- {
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
- {
- update_stmt_if_modified (bsi_stmt (bsi));
- }
- }
- }
+ if (need_ssa_update_p ())
+ update_ssa (TODO_update_ssa);
+ timevar_pop (TV_TREE_MAY_ALIAS);
+
+ return 0;
}
-struct tree_opt_pass pass_may_alias =
-{
- "alias", /* name */
- NULL, /* gate */
- compute_may_aliases, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_TREE_MAY_ALIAS, /* tv_id */
- PROP_cfg | PROP_ssa, /* properties_required */
- PROP_alias, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func | TODO_update_ssa
- | TODO_ggc_collect | TODO_verify_ssa
- | TODO_verify_stmts, /* todo_flags_finish */
- 0 /* letter */
-};
-
-
/* Data structure used to count the number of dereferences to PTR
inside an expression. */
struct count_ptr_d
/* Count the number of direct and indirect uses for pointer PTR in
- statement STMT. The two counts are stored in *NUM_USES_P and
- *NUM_DEREFS_P respectively. *IS_STORE_P is set to 'true' if at
- least one of those dereferences is a store operation. */
+ statement STMT. The number of direct uses is stored in
+ *NUM_USES_P. Indirect references are counted separately depending
+ on whether they are store or load operations. The counts are
+ stored in *NUM_STORES_P and *NUM_LOADS_P. */
void
count_uses_and_derefs (tree ptr, tree stmt, unsigned *num_uses_p,
- unsigned *num_derefs_p, bool *is_store)
+ unsigned *num_loads_p, unsigned *num_stores_p)
{
ssa_op_iter i;
tree use;
*num_uses_p = 0;
- *num_derefs_p = 0;
- *is_store = false;
+ *num_loads_p = 0;
+ *num_stores_p = 0;
/* Find out the total number of uses of PTR in STMT. */
FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE)
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) == MODIFY_EXPR
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
|| (TREE_CODE (stmt) == RETURN_EXPR
- && TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_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) == MODIFY_EXPR)
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
{
- lhs = TREE_OPERAND (stmt, 0);
- rhs = TREE_OPERAND (stmt, 1);
+ 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 = TREE_OPERAND (e, 0);
- rhs = TREE_OPERAND (e, 1);
+ lhs = GIMPLE_STMT_OPERAND (e, 0);
+ rhs = GIMPLE_STMT_OPERAND (e, 1);
}
else if (TREE_CODE (stmt) == ASM_EXPR)
{
rhs = stmt;
}
- if (lhs && (TREE_CODE (lhs) == TREE_LIST || EXPR_P (lhs)))
+ if (lhs
+ && (TREE_CODE (lhs) == TREE_LIST
+ || EXPR_P (lhs)
+ || GIMPLE_STMT_P (lhs)))
{
struct count_ptr_d count;
count.ptr = ptr;
count.count = 0;
walk_tree (&lhs, count_ptr_derefs, &count, NULL);
- *is_store = true;
- *num_derefs_p = count.count;
+ *num_stores_p = count.count;
}
- if (rhs && (TREE_CODE (rhs) == TREE_LIST || EXPR_P (rhs)))
+ if (rhs
+ && (TREE_CODE (rhs) == TREE_LIST
+ || EXPR_P (rhs)
+ || GIMPLE_STMT_P (rhs)))
{
struct count_ptr_d count;
count.ptr = ptr;
count.count = 0;
walk_tree (&rhs, count_ptr_derefs, &count, NULL);
- *num_derefs_p += count.count;
+ *num_loads_p = count.count;
+ }
+ }
+
+ gcc_assert (*num_uses_p >= *num_loads_p + *num_stores_p);
+}
+
+/* Remove memory references stats for function FN. */
+
+void
+delete_mem_ref_stats (struct function *fn)
+{
+ if (gimple_mem_ref_stats (fn)->mem_sym_stats)
+ {
+ free_alloc_pool (mem_sym_stats_pool);
+ pointer_map_destroy (gimple_mem_ref_stats (fn)->mem_sym_stats);
+ }
+ gimple_mem_ref_stats (fn)->mem_sym_stats = NULL;
+}
+
+
+/* Initialize memory reference stats. */
+
+static void
+init_mem_ref_stats (void)
+{
+ struct mem_ref_stats_d *mem_ref_stats = gimple_mem_ref_stats (cfun);
+
+ mem_sym_stats_pool = create_alloc_pool ("Mem sym stats",
+ sizeof (struct mem_sym_stats_d),
+ 100);
+ memset (mem_ref_stats, 0, sizeof (struct mem_ref_stats_d));
+ mem_ref_stats->mem_sym_stats = pointer_map_create ();
+}
+
+
+/* Helper for init_alias_info. Reset existing aliasing information. */
+
+static void
+reset_alias_info (void)
+{
+ referenced_var_iterator rvi;
+ tree var;
+ unsigned i;
+ bitmap active_nmts, all_nmts;
+
+ /* Clear the set of addressable variables. We do not need to clear
+ the TREE_ADDRESSABLE bit on every symbol because we are going to
+ re-compute addressability here. */
+ bitmap_clear (gimple_addressable_vars (cfun));
+
+ active_nmts = BITMAP_ALLOC (&alias_bitmap_obstack);
+ all_nmts = BITMAP_ALLOC (&alias_bitmap_obstack);
+
+ /* Clear flow-insensitive alias information from each symbol. */
+ FOR_EACH_REFERENCED_VAR (var, rvi)
+ {
+ if (is_gimple_reg (var))
+ continue;
+
+ if (MTAG_P (var))
+ MTAG_ALIASES (var) = NULL;
+
+ /* Memory partition information will be computed from scratch. */
+ if (TREE_CODE (var) == MEMORY_PARTITION_TAG)
+ MPT_SYMBOLS (var) = NULL;
+
+ /* Collect all the name tags to determine if we have any
+ orphaned that need to be removed from the IL. A name tag
+ will be orphaned if it is not associated with any active SSA
+ name. */
+ if (TREE_CODE (var) == NAME_MEMORY_TAG)
+ bitmap_set_bit (all_nmts, DECL_UID (var));
+
+ /* Since we are about to re-discover call-clobbered
+ variables, clear the call-clobbered flag. Variables that
+ are intrinsically call-clobbered (globals, local statics,
+ etc) will not be marked by the aliasing code, so we can't
+ remove them from CALL_CLOBBERED_VARS.
+
+ NB: STRUCT_FIELDS are still call clobbered if they are for a
+ global variable, so we *don't* clear their call clobberedness
+ just because they are tags, though we will clear it if they
+ aren't for global variables. */
+ if (TREE_CODE (var) == NAME_MEMORY_TAG
+ || TREE_CODE (var) == SYMBOL_MEMORY_TAG
+ || TREE_CODE (var) == MEMORY_PARTITION_TAG
+ || !is_global_var (var))
+ clear_call_clobbered (var);
+ }
+
+ /* Clear flow-sensitive points-to information from each SSA name. */
+ for (i = 1; i < num_ssa_names; i++)
+ {
+ tree name = ssa_name (i);
+
+ if (!name || !POINTER_TYPE_P (TREE_TYPE (name)))
+ continue;
+
+ if (SSA_NAME_PTR_INFO (name))
+ {
+ struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
+
+ /* Clear all the flags but keep the name tag to
+ avoid creating new temporaries unnecessarily. If
+ this pointer is found to point to a subset or
+ superset of its former points-to set, then a new
+ tag will need to be created in create_name_tags. */
+ pi->pt_anything = 0;
+ pi->pt_null = 0;
+ pi->value_escapes_p = 0;
+ pi->is_dereferenced = 0;
+ if (pi->pt_vars)
+ bitmap_clear (pi->pt_vars);
+
+ /* Add NAME's name tag to the set of active tags. */
+ if (pi->name_mem_tag)
+ bitmap_set_bit (active_nmts, DECL_UID (pi->name_mem_tag));
}
}
- gcc_assert (*num_uses_p >= *num_derefs_p);
+ /* Name memory tags that are no longer associated with an SSA name
+ are considered stale and should be removed from the IL. All the
+ name tags that are in the set ALL_NMTS but not in ACTIVE_NMTS are
+ considered stale and marked for renaming. */
+ bitmap_and_compl_into (all_nmts, active_nmts);
+ mark_set_for_renaming (all_nmts);
+
+ BITMAP_FREE (all_nmts);
+ BITMAP_FREE (active_nmts);
}
+
/* Initialize the data structures used for alias analysis. */
static struct alias_info *
referenced_var_iterator rvi;
tree var;
- bitmap_obstack_initialize (&alias_obstack);
- ai = xcalloc (1, sizeof (struct alias_info));
+ ai = XCNEW (struct alias_info);
ai->ssa_names_visited = sbitmap_alloc (num_ssa_names);
sbitmap_zero (ai->ssa_names_visited);
- VARRAY_TREE_INIT (ai->processed_ptrs, 50, "processed_ptrs");
- ai->written_vars = BITMAP_ALLOC (&alias_obstack);
- ai->dereferenced_ptrs_store = BITMAP_ALLOC (&alias_obstack);
- ai->dereferenced_ptrs_load = BITMAP_ALLOC (&alias_obstack);
+ 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 ();
+
+ /* Clear out all memory reference stats. */
+ init_mem_ref_stats ();
/* If aliases have been computed before, clear existing information. */
- if (aliases_computed_p)
+ if (gimple_aliases_computed_p (cfun))
+ reset_alias_info ();
+ else
{
- unsigned i;
-
- /* Similarly, clear the set of addressable variables. In this
- case, we can just clear the set because addressability is
- only computed here. */
- bitmap_clear (addressable_vars);
-
- /* Clear flow-insensitive alias information from each symbol. */
+ /* 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)
- {
- var_ann_t ann = var_ann (var);
-
- ann->is_alias_tag = 0;
- ann->may_aliases = NULL;
- NUM_REFERENCES_CLEAR (ann);
-
- /* 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 (ann->mem_tag_kind == NAME_TAG
- || ann->mem_tag_kind == TYPE_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);
- }
- }
+ if (!is_gimple_reg (var))
+ mark_sym_for_renaming (var);
}
/* Next time, we will need to reset alias information. */
- aliases_computed_p = true;
+ cfun->gimple_df->aliases_computed_p = true;
+ if (alias_bitmap_obstack.elements != NULL)
+ bitmap_obstack_release (&alias_bitmap_obstack);
+ bitmap_obstack_initialize (&alias_bitmap_obstack);
return ai;
}
delete_alias_info (struct alias_info *ai)
{
size_t i;
- referenced_var_iterator rvi;
- tree var;
sbitmap_free (ai->ssa_names_visited);
- ai->processed_ptrs = NULL;
+
+ VEC_free (tree, heap, ai->processed_ptrs);
for (i = 0; i < ai->num_addressable_vars; i++)
free (ai->addressable_vars[i]);
-
- FOR_EACH_REFERENCED_VAR(var, rvi)
- {
- var_ann_t ann = var_ann (var);
- NUM_REFERENCES_CLEAR (ann);
- }
-
free (ai->addressable_vars);
-
+
for (i = 0; i < ai->num_pointers; i++)
free (ai->pointers[i]);
free (ai->pointers);
- BITMAP_FREE (ai->written_vars);
- BITMAP_FREE (ai->dereferenced_ptrs_store);
- BITMAP_FREE (ai->dereferenced_ptrs_load);
- bitmap_obstack_release (&alias_obstack);
+ pointer_set_destroy (ai->written_vars);
+ pointer_set_destroy (ai->dereferenced_ptrs_store);
+ pointer_set_destroy (ai->dereferenced_ptrs_load);
free (ai);
+ delete_mem_ref_stats (cfun);
delete_points_to_sets ();
}
+/* Used for hashing to identify pointer infos with identical
+ pt_vars bitmaps. */
+
+static int
+eq_ptr_info (const void *p1, const void *p2)
+{
+ 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
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);
continue;
}
- if (pi->pt_vars && !bitmap_empty_p (pi->pt_vars))
- {
- size_t j;
- tree old_name_tag = pi->name_mem_tag;
-
- /* 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). */
- for (j = 1; j < i; j++)
- {
- tree q = ssa_name (j);
- struct ptr_info_def *qi;
-
- if (!q || !POINTER_TYPE_P (TREE_TYPE (q)))
- 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;
- qi = SSA_NAME_PTR_INFO (q);
+ ptr_hash = htab_create (10, ptr_info_hash, eq_ptr_info, NULL);
- if (qi
- && qi->pt_vars
- && qi->name_mem_tag
- && bitmap_equal_p (pi->pt_vars, qi->pt_vars))
- {
- pi->name_mem_tag = qi->name_mem_tag;
- break;
- }
- }
+ /* 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);
- }
- else
- {
- /* If the pointer does not point to a known spot, we should
- use type tags. */
- set_pt_anything (ptr);
- continue;
}
-
+
+ /* 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);
+
+ /* Inherit volatility from the pointed-to type. */
TREE_THIS_VOLATILE (pi->name_mem_tag)
- |= TREE_THIS_VOLATILE (TREE_TYPE (TREE_TYPE (ptr)));
-
+ |= TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (ptr)));
+
/* Mark the new name tag for renaming. */
mark_sym_for_renaming (pi->name_mem_tag);
}
+
+ htab_delete (ptr_hash);
+
+ VEC_free (tree, heap, with_ptvars);
+}
+
+
+/* Union the alias set SET into the may-aliases for TAG. */
+
+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);
}
compute_flow_sensitive_aliasing (struct alias_info *ai)
{
size_t i;
+ tree ptr;
+
+ timevar_push (TV_FLOW_SENSITIVE);
+ set_used_smts ();
- for (i = 0; i < VARRAY_ACTIVE_SIZE (ai->processed_ptrs); i++)
+ for (i = 0; VEC_iterate (tree, ai->processed_ptrs, i, ptr); i++)
{
- tree ptr = VARRAY_TREE (ai->processed_ptrs, i);
if (!find_what_p_points_to (ptr))
set_pt_anything (ptr);
}
create_name_tags ();
- for (i = 0; i < VARRAY_ACTIVE_SIZE (ai->processed_ptrs); i++)
+ for (i = 0; VEC_iterate (tree, ai->processed_ptrs, i, ptr); i++)
{
- unsigned j;
- tree ptr = VARRAY_TREE (ai->processed_ptrs, i);
struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
- var_ann_t v_ann = var_ann (SSA_NAME_VAR (ptr));
- bitmap_iterator bi;
-
- if (pi->value_escapes_p || pi->pt_anything)
- {
- /* If PTR escapes or may point to anything, then its associated
- memory tags and pointed-to variables are call-clobbered. */
- if (pi->name_mem_tag)
- mark_call_clobbered (pi->name_mem_tag);
-
- if (v_ann->type_mem_tag)
- mark_call_clobbered (v_ann->type_mem_tag);
-
- if (pi->pt_vars)
- EXECUTE_IF_SET_IN_BITMAP (pi->pt_vars, 0, j, bi)
- mark_call_clobbered (referenced_var (j));
- }
+ 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)
- EXECUTE_IF_SET_IN_BITMAP (pi->pt_vars, 0, j, bi)
- {
- add_may_alias (pi->name_mem_tag, referenced_var (j));
- add_may_alias (v_ann->type_mem_tag, referenced_var (j));
- }
-
- /* If the name tag is call clobbered, so is the type tag
- associated with the base VAR_DECL. */
- if (pi->name_mem_tag
- && v_ann->type_mem_tag
- && is_call_clobbered (pi->name_mem_tag))
- mark_call_clobbered (v_ann->type_mem_tag);
+ {
+ 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));
+ }
+ }
}
+ timevar_pop (TV_FLOW_SENSITIVE);
}
+/* 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 type
- memory tag (TMT) if their alias sets conflict. V is then marked as
- an alias tag so that the operand scanner knows that statements
+ 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
{
size_t i;
- /* Initialize counter for the total number of virtual operands that
- aliasing will introduce. When AI->TOTAL_ALIAS_VOPS goes beyond the
- threshold set by --params max-alias-vops, we enable alias
- grouping. */
- ai->total_alias_vops = 0;
-
+ timevar_push (TV_FLOW_INSENSITIVE);
/* For every pointer P, determine which addressable variables may alias
- with P's type memory tag. */
+ 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 = var_ann (p_map->var)->type_mem_tag;
- var_ann_t tag_ann = var_ann (tag);
+ tree tag = symbol_mem_tag (p_map->var);
+ tree var;
- p_map->total_alias_vops = 0;
- p_map->may_aliases = BITMAP_ALLOC (&alias_obstack);
+ /* 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;
- tree var;
bool tag_stored_p, var_stored_p;
v_map = ai->addressable_vars[j];
/* 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.
-
- Note this is effectively random accessing elements in
- the sparse bitset, which can be highly inefficient.
- So we first check the call_clobbered status of the
- tag and variable before querying the bitmap. */
- tag_stored_p = is_call_clobbered (tag)
- || bitmap_bit_p (ai->written_vars, DECL_UID (tag));
- var_stored_p = is_call_clobbered (var)
- || bitmap_bit_p (ai->written_vars, DECL_UID (var));
+ 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))
{
- subvar_t svars;
- size_t num_tag_refs, num_var_refs;
-
- num_tag_refs = NUM_REFERENCES (tag_ann);
- num_var_refs = NUM_REFERENCES (v_ann);
+ /* 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. */
-
- /* If this is an aggregate, we may have subvariables for it
- that need to be pointed to. */
- if (var_can_have_subvars (var)
- && (svars = get_subvars_for_var (var)))
- {
- subvar_t sv;
-
- for (sv = svars; sv; sv = sv->next)
- {
- add_may_alias (tag, sv->var);
- /* Update the bitmap used to represent TAG's alias set
- in case we need to group aliases. */
- bitmap_set_bit (p_map->may_aliases, DECL_UID (sv->var));
- }
- }
- else
- {
- add_may_alias (tag, var);
- /* Update the bitmap used to represent TAG's alias set
- in case we need to group aliases. */
- bitmap_set_bit (p_map->may_aliases, DECL_UID (var));
- }
-
- /* Update the total number of virtual operands due to
- aliasing. Since we are adding one more alias to TAG's
- may-aliases set, the total number of virtual operands due
- to aliasing will be increased by the number of references
- made to VAR and TAG (every reference to TAG will also
- count as a reference to VAR). */
- ai->total_alias_vops += (num_var_refs + num_tag_refs);
- p_map->total_alias_vops += (num_var_refs + num_tag_refs);
-
-
+ add_may_alias (tag, var);
}
}
}
tags with conflicting alias set numbers but no aliased symbols in
common.
- For example, suppose that we have two memory tags TMT.1 and TMT.2
+ For example, suppose that we have two memory tags SMT.1 and SMT.2
such that
- may-aliases (TMT.1) = { a }
- may-aliases (TMT.2) = { b }
+ may-aliases (SMT.1) = { a }
+ may-aliases (SMT.2) = { b }
- and the alias set number of TMT.1 conflicts with that of TMT.2.
+ 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
- TMT.1 and TMT.2 will seem independent of each other, which will
+ 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).
{
size_t j;
struct alias_map_d *p_map1 = ai->pointers[i];
- tree tag1 = var_ann (p_map1->var)->type_mem_tag;
- bitmap may_aliases1 = p_map1->may_aliases;
+ 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 = var_ann (p_map2->var)->type_mem_tag;
- bitmap may_aliases2 = p_map2->may_aliases;
+ 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))
/* The two pointers may alias each other. If they already have
symbols in common, do nothing. */
- if (bitmap_intersect_p (may_aliases1, may_aliases2))
+ if (have_common_aliases_p (may_aliases1, may_aliases2))
continue;
- if (!bitmap_empty_p (may_aliases2))
+ if (may_aliases2 && !bitmap_empty_p (may_aliases2))
{
- unsigned int k;
- bitmap_iterator bi;
-
- /* Add all the aliases for TAG2 into TAG1's alias set.
- FIXME, update grouping heuristic counters. */
- EXECUTE_IF_SET_IN_BITMAP (may_aliases2, 0, k, bi)
- add_may_alias (tag1, referenced_var (k));
- bitmap_ior_into (may_aliases1, 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);
- bitmap_set_bit (may_aliases1, DECL_UID (tag2));
}
}
- }
-
- if (dump_file)
- fprintf (dump_file, "\n%s: Total number of aliased vops: %ld\n",
- get_name (current_function_decl),
- ai->total_alias_vops);
-
- /* Determine if we need to enable alias grouping. */
- if (ai->total_alias_vops >= MAX_ALIASED_VOPS)
- group_aliases (ai);
-}
-
-
-/* Comparison function for qsort used in group_aliases. */
-
-static int
-total_alias_vops_cmp (const void *p, const void *q)
-{
- const struct alias_map_d **p1 = (const struct alias_map_d **)p;
- const struct alias_map_d **p2 = (const struct alias_map_d **)q;
- long n1 = (*p1)->total_alias_vops;
- long n2 = (*p2)->total_alias_vops;
- /* We want to sort in descending order. */
- return (n1 > n2 ? -1 : (n1 == n2) ? 0 : 1);
-}
-
-/* Group all the aliases for TAG to make TAG represent all the
- variables in its alias set. Update the total number
- of virtual operands due to aliasing (AI->TOTAL_ALIAS_VOPS). This
- function will make TAG be the unique alias tag for all the
- variables in its may-aliases. So, given:
-
- may-aliases(TAG) = { V1, V2, V3 }
-
- This function will group the variables into:
-
- may-aliases(V1) = { TAG }
- may-aliases(V2) = { TAG }
- may-aliases(V2) = { TAG } */
-
-static void
-group_aliases_into (tree tag, bitmap tag_aliases, struct alias_info *ai)
-{
- unsigned int i;
- var_ann_t tag_ann = var_ann (tag);
- size_t num_tag_refs = NUM_REFERENCES (tag_ann);
- bitmap_iterator bi;
-
- EXECUTE_IF_SET_IN_BITMAP (tag_aliases, 0, i, bi)
- {
- tree var = referenced_var (i);
- var_ann_t ann = var_ann (var);
-
- /* Make TAG the unique alias of VAR. */
- ann->is_alias_tag = 0;
- ann->may_aliases = NULL;
-
- /* Note that VAR and TAG may be the same if the function has no
- addressable variables (see the discussion at the end of
- setup_pointers_and_addressables). */
- if (var != tag)
- add_may_alias (var, tag);
-
- /* Reduce total number of virtual operands contributed
- by TAG on behalf of VAR. Notice that the references to VAR
- itself won't be removed. We will merely replace them with
- references to TAG. */
- ai->total_alias_vops -= num_tag_refs;
}
-
- /* We have reduced the number of virtual operands that TAG makes on
- behalf of all the variables formerly aliased with it. However,
- we have also "removed" all the virtual operands for TAG itself,
- so we add them back. */
- ai->total_alias_vops += num_tag_refs;
-
- /* TAG no longer has any aliases. */
- tag_ann->may_aliases = NULL;
+ timevar_pop (TV_FLOW_INSENSITIVE);
}
-/* Group may-aliases sets to reduce the number of virtual operands due
- to aliasing.
-
- 1- Sort the list of pointers in decreasing number of contributed
- virtual operands.
-
- 2- Take the first entry in AI->POINTERS and revert the role of
- the memory tag and its aliases. Usually, whenever an aliased
- variable Vi is found to alias with a memory tag T, we add Vi
- to the may-aliases set for T. Meaning that after alias
- analysis, we will have:
-
- may-aliases(T) = { V1, V2, V3, ..., Vn }
-
- This means that every statement that references T, will get 'n'
- virtual operands for each of the Vi tags. But, when alias
- grouping is enabled, we make T an alias tag and add it to the
- alias set of all the Vi variables:
-
- may-aliases(V1) = { T }
- may-aliases(V2) = { T }
- ...
- may-aliases(Vn) = { T }
-
- This has two effects: (a) statements referencing T will only get
- a single virtual operand, and, (b) all the variables Vi will now
- appear to alias each other. So, we lose alias precision to
- improve compile time. But, in theory, a program with such a high
- level of aliasing should not be very optimizable in the first
- place.
-
- 3- Since variables may be in the alias set of more than one
- memory tag, the grouping done in step (2) needs to be extended
- to all the memory tags that have a non-empty intersection with
- the may-aliases set of tag T. For instance, if we originally
- had these may-aliases sets:
+/* Finalize may-alias information for ref-all pointers. Traverse all
+ the addressable variables found in setup_pointers_and_addressables.
- may-aliases(T) = { V1, V2, V3 }
- may-aliases(R) = { V2, V4 }
-
- In step (2) we would have reverted the aliases for T as:
-
- may-aliases(V1) = { T }
- may-aliases(V2) = { T }
- may-aliases(V3) = { T }
-
- But note that now V2 is no longer aliased with R. We could
- add R to may-aliases(V2), but we are in the process of
- grouping aliases to reduce virtual operands so what we do is
- add V4 to the grouping to obtain:
-
- may-aliases(V1) = { T }
- may-aliases(V2) = { T }
- may-aliases(V3) = { T }
- may-aliases(V4) = { T }
-
- 4- If the total number of virtual operands due to aliasing is
- still above the threshold set by max-alias-vops, go back to (2). */
+ 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
-group_aliases (struct alias_info *ai)
-{
- size_t i;
-
- /* Sort the POINTERS array in descending order of contributed
- virtual operands. */
- qsort (ai->pointers, ai->num_pointers, sizeof (struct alias_map_d *),
- total_alias_vops_cmp);
-
- /* For every pointer in AI->POINTERS, reverse the roles of its tag
- and the tag's may-aliases set. */
- for (i = 0; i < ai->num_pointers; i++)
- {
- size_t j;
- tree tag1 = var_ann (ai->pointers[i]->var)->type_mem_tag;
- bitmap tag1_aliases = ai->pointers[i]->may_aliases;
-
- /* Skip tags that have been grouped already. */
- if (ai->pointers[i]->grouped_p)
- continue;
-
- /* See if TAG1 had any aliases in common with other type tags.
- If we find a TAG2 with common aliases with TAG1, add TAG2's
- aliases into TAG1. */
- for (j = i + 1; j < ai->num_pointers; j++)
- {
- bitmap tag2_aliases = ai->pointers[j]->may_aliases;
-
- if (bitmap_intersect_p (tag1_aliases, tag2_aliases))
- {
- tree tag2 = var_ann (ai->pointers[j]->var)->type_mem_tag;
-
- bitmap_ior_into (tag1_aliases, tag2_aliases);
-
- /* TAG2 does not need its aliases anymore. */
- bitmap_clear (tag2_aliases);
- var_ann (tag2)->may_aliases = NULL;
-
- /* TAG1 is the unique alias of TAG2. */
- add_may_alias (tag2, tag1);
-
- ai->pointers[j]->grouped_p = true;
- }
- }
-
- /* Now group all the aliases we collected into TAG1. */
- group_aliases_into (tag1, tag1_aliases, ai);
-
- /* If we've reduced total number of virtual operands below the
- threshold, stop. */
- if (ai->total_alias_vops < MAX_ALIASED_VOPS)
- break;
- }
-
- /* Finally, all the variables that have been grouped cannot be in
- the may-alias set of name memory tags. Suppose that we have
- grouped the aliases in this code so that may-aliases(a) = TMT.20
-
- p_5 = &a;
- ...
- # a_9 = V_MAY_DEF <a_8>
- p_5->field = 0
- ... Several modifications to TMT.20 ...
- # VUSE <a_9>
- x_30 = p_5->field
-
- Since p_5 points to 'a', the optimizers will try to propagate 0
- into p_5->field, but that is wrong because there have been
- modifications to 'TMT.20' in between. To prevent this we have to
- replace 'a' with 'TMT.20' in the name tag of p_5. */
- for (i = 0; i < VARRAY_ACTIVE_SIZE (ai->processed_ptrs); i++)
- {
- size_t j;
- tree ptr = VARRAY_TREE (ai->processed_ptrs, i);
- tree name_tag = SSA_NAME_PTR_INFO (ptr)->name_mem_tag;
- varray_type aliases;
-
- if (name_tag == NULL_TREE)
- continue;
-
- aliases = var_ann (name_tag)->may_aliases;
- for (j = 0; aliases && j < VARRAY_ACTIVE_SIZE (aliases); j++)
- {
- tree alias = VARRAY_TREE (aliases, j);
- var_ann_t ann = var_ann (alias);
-
- if ((ann->mem_tag_kind == NOT_A_TAG
- || ann->mem_tag_kind == STRUCT_FIELD)
- && ann->may_aliases)
- {
- tree new_alias;
+finalize_ref_all_pointers (struct alias_info *ai)
+{
+ size_t i;
- gcc_assert (VARRAY_ACTIVE_SIZE (ann->may_aliases) == 1);
+ /* 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);
+ }
- new_alias = VARRAY_TREE (ann->may_aliases, 0);
- replace_may_alias (name_tag, j, new_alias);
- }
+ /* 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;
+ /* Avoid adding to self and clean up. */
+ if (PTR_IS_REF_ALL (ptr))
+ {
+ struct ptr_info_def *pi = get_ptr_info (ptr);
+ if (pi->is_dereferenced)
+ pi->pt_anything = 0;
+ continue;
}
+ tag = symbol_mem_tag (ptr);
+ if (is_call_clobbered (tag))
+ add_may_alias (ai->ref_all_symbol_mem_tag, tag);
}
- if (dump_file)
- fprintf (dump_file,
- "%s: Total number of aliased vops after grouping: %ld%s\n",
- get_name (current_function_decl),
- ai->total_alias_vops,
- (ai->total_alias_vops < 0) ? " (negative values are OK)" : "");
}
create_alias_map_for (tree var, struct alias_info *ai)
{
struct alias_map_d *alias_map;
- alias_map = xcalloc (1, sizeof (*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;
static void
setup_pointers_and_addressables (struct alias_info *ai)
{
- size_t n_vars, num_addressable_vars, num_pointers;
+ size_t num_addressable_vars, num_pointers;
referenced_var_iterator rvi;
tree var;
VEC (tree, heap) *varvec = NULL;
/* Since we don't keep track of volatile variables, assume that
these pointers are used in indirect store operations. */
if (TREE_THIS_VOLATILE (var))
- bitmap_set_bit (ai->dereferenced_ptrs_store, DECL_UID (var));
+ pointer_set_insert (ai->dereferenced_ptrs_store, var);
num_pointers++;
}
/* 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 type tags are
+ non-addressable below and only pointers with unique symbol tags are
going to be added to POINTERS. */
- ai->addressable_vars = xcalloc (num_addressable_vars,
- sizeof (struct alias_map_d *));
- ai->pointers = xcalloc (num_pointers, sizeof (struct alias_map_d *));
+ 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;
- /* Since we will be creating type memory tags within this loop, cache the
- value of NUM_REFERENCED_VARS to avoid processing the additional tags
- unnecessarily. */
- n_vars = num_referenced_vars;
-
FOR_EACH_REFERENCED_VAR_SAFE (var, varvec, srvi)
{
- var_ann_t v_ann = var_ann (var);
subvar_t svars;
/* Name memory tags already have flow-sensitive aliasing
information, so they need not be processed by
- compute_flow_insensitive_aliasing. Similarly, type memory
+ 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 (v_ann->mem_tag_kind != NOT_A_TAG
- && v_ann->mem_tag_kind != STRUCT_FIELD)
+ if (MTAG_P (var) && TREE_CODE (var) != STRUCT_FIELD_TAG)
continue;
/* Remove the ADDRESSABLE flag from every addressable variable whose
cleanup passes. */
if (TREE_ADDRESSABLE (var))
{
- if (!bitmap_bit_p (addressable_vars, DECL_UID (var))
+ if (!bitmap_bit_p (gimple_addressable_vars (cfun), DECL_UID (var))
&& TREE_CODE (var) != RESULT_DECL
&& !is_global_var (var))
{
if (var_can_have_subvars (var)
&& (svars = get_subvars_for_var (var)))
{
- subvar_t sv;
+ unsigned int i;
+ tree subvar;
- for (sv = svars; sv; sv = sv->next)
+ for (i = 0; VEC_iterate (tree, svars, i, subvar); ++i)
{
- if (bitmap_bit_p (addressable_vars, DECL_UID (sv->var)))
+ if (bitmap_bit_p (gimple_addressable_vars (cfun),
+ DECL_UID (subvar)))
okay_to_mark = false;
- mark_sym_for_renaming (sv->var);
+ mark_sym_for_renaming (subvar);
}
}
addressable bit, so that it can be optimized as a
regular variable. */
if (okay_to_mark)
- mark_non_addressable (var);
+ {
+ /* 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);
+ }
}
}
entry in ADDRESSABLE_VARS for VAR. */
if (may_be_aliased (var))
{
- create_alias_map_for (var, ai);
+ if (!var_can_have_subvars (var)
+ || get_subvars_for_var (var) == NULL)
+ create_alias_map_for (var, ai);
+
mark_sym_for_renaming (var);
}
/* Add pointer variables that have been dereferenced to the POINTERS
- array and create a type memory tag for them. */
+ array and create a symbol memory tag for them. */
if (POINTER_TYPE_P (TREE_TYPE (var)))
{
- if ((bitmap_bit_p (ai->dereferenced_ptrs_store, DECL_UID (var))
- || bitmap_bit_p (ai->dereferenced_ptrs_load, DECL_UID (var))))
+ if ((pointer_set_contains (ai->dereferenced_ptrs_store, var)
+ || pointer_set_contains (ai->dereferenced_ptrs_load, var)))
{
- tree tag;
+ 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_tmt_for (var, ai);
+ tag = get_smt_for (var, ai);
t_ann = var_ann (tag);
- /* The type tag will need to be renamed into SSA
+ /* The symbol tag will need to be renamed into SSA
afterwards. Note that we cannot do this inside
- get_tmt_for because aliasing may run multiple times
- and we only create type tags the first time. */
+ 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. */
- if (v_ann->type_mem_tag)
- mark_sym_for_renaming (v_ann->type_mem_tag);
+ old_tag = symbol_mem_tag (var);
+ if (old_tag)
+ mark_sym_for_renaming (old_tag);
/* Associate the tag with pointer VAR. */
- v_ann->type_mem_tag = tag;
+ 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 (bitmap_bit_p (ai->dereferenced_ptrs_store, DECL_UID (var)))
- bitmap_set_bit (ai->written_vars, DECL_UID (tag));
-
- /* If pointer VAR is a global variable or a PARM_DECL,
- then its memory tag should be considered a global
- variable. */
- if (TREE_CODE (var) == PARM_DECL || is_global_var (var))
- mark_call_clobbered (tag);
-
- /* All the dereferences of pointer VAR count as
- references of TAG. Since TAG can be associated with
- several pointers, add the dereferences of VAR to the
- TAG. */
- NUM_REFERENCES_SET (t_ann,
- NUM_REFERENCES (t_ann)
- + NUM_REFERENCES (v_ann));
+ 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
- type memory tag, remove it and mark the old tag for
+ symbol memory tag, remove it and mark the old tag for
renaming to remove it out of the IL. */
- var_ann_t ann = var_ann (var);
- tree tag = ann->type_mem_tag;
+ tree tag = symbol_mem_tag (var);
if (tag)
{
mark_sym_for_renaming (tag);
- ann->type_mem_tag = NULL_TREE;
+ set_symbol_mem_tag (var, NULL_TREE);
}
}
}
}
+
VEC_free (tree, heap, varvec);
}
-/* Determine whether to use .GLOBAL_VAR to model call clobbering semantics. At
- every call site, we need to emit V_MAY_DEF expressions to represent the
- clobbering effects of the call for variables whose address escapes the
- current function.
-
- One approach is to group all call-clobbered variables into a single
- representative that is used as an alias of every call-clobbered variable
- (.GLOBAL_VAR). This works well, but it ties the optimizer hands because
- references to any call clobbered variable is a reference to .GLOBAL_VAR.
-
- The second approach is to emit a clobbering V_MAY_DEF for every
- call-clobbered variable at call sites. This is the preferred way in terms
- of optimization opportunities but it may create too many V_MAY_DEF operands
- if there are many call clobbered variables and function calls in the
- function.
-
- To decide whether or not to use .GLOBAL_VAR we multiply the number of
- function calls found by the number of call-clobbered variables. If that
- product is beyond a certain threshold, as determined by the parameterized
- values shown below, we use .GLOBAL_VAR.
-
- FIXME. This heuristic should be improved. One idea is to use several
- .GLOBAL_VARs of different types instead of a single one. The thresholds
- have been derived from a typical bootstrap cycle, including all target
- libraries. Compile times were found increase by ~1% compared to using
- .GLOBAL_VAR. */
+/* 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. */
static void
-maybe_create_global_var (struct alias_info *ai)
+maybe_create_global_var (void)
{
- unsigned i, n_clobbered;
- bitmap_iterator bi;
-
/* No need to create it, if we have one already. */
- if (global_var == NULL_TREE)
+ if (gimple_global_var (cfun) == NULL_TREE)
{
- /* Count all the call-clobbered variables. */
- n_clobbered = 0;
- EXECUTE_IF_SET_IN_BITMAP (call_clobbered_vars, 0, i, bi)
- {
- n_clobbered++;
- }
-
- /* If the number of virtual operands that would be needed to
- model all the call-clobbered variables is larger than
- GLOBAL_VAR_THRESHOLD, create .GLOBAL_VAR.
+ struct mem_ref_stats_d *stats = gimple_mem_ref_stats (cfun);
- Also create .GLOBAL_VAR if there are no call-clobbered
+ /* 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:
So, if we have some pure/const and some regular calls in the
program we create .GLOBAL_VAR to avoid missing these
relations. */
- if (ai->num_calls_found * n_clobbered >= (size_t) GLOBAL_VAR_THRESHOLD
- || (n_clobbered == 0
- && ai->num_calls_found > 0
- && ai->num_pure_const_calls_found > 0
- && ai->num_calls_found > ai->num_pure_const_calls_found))
+ if (bitmap_empty_p (gimple_call_clobbered_vars (cfun))
+ && stats->num_call_sites > 0
+ && stats->num_pure_const_call_sites > 0
+ && stats->num_call_sites > stats->num_pure_const_call_sites)
create_global_var ();
}
-
- /* Mark all call-clobbered symbols for renaming. Since the initial
- rewrite into SSA ignored all call sites, we may need to rename
- .GLOBAL_VAR and the call-clobbered variables. */
- EXECUTE_IF_SET_IN_BITMAP (call_clobbered_vars, 0, i, bi)
- {
- tree var = referenced_var (i);
-
- /* If the function has calls to clobbering functions and
- .GLOBAL_VAR has been created, make it an alias for all
- call-clobbered variables. */
- if (global_var && var != global_var)
- {
- subvar_t svars;
- add_may_alias (var, global_var);
- if (var_can_have_subvars (var)
- && (svars = get_subvars_for_var (var)))
- {
- subvar_t sv;
- for (sv = svars; sv; sv = sv->next)
- mark_sym_for_renaming (sv->var);
- }
- }
-
- mark_sym_for_renaming (var);
- }
}
VAR_ALIAS_SET is the alias set for VAR. */
static bool
-may_alias_p (tree ptr, HOST_WIDE_INT mem_alias_set,
- tree var, HOST_WIDE_INT var_alias_set,
+may_alias_p (tree ptr, alias_set_type mem_alias_set,
+ tree var, alias_set_type var_alias_set,
bool alias_set_only)
{
tree mem;
- var_ann_t m_ann;
alias_stats.alias_queries++;
alias_stats.simple_queries++;
/* By convention, a variable cannot alias itself. */
- mem = var_ann (ptr)->type_mem_tag;
+ mem = symbol_mem_tag (ptr);
if (mem == var)
{
alias_stats.alias_noalias++;
alias_stats.simple_resolved++;
return false;
}
-
- /* If -fargument-noalias-global is >1, pointer arguments may
+
+ /* 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)
return false;
}
- m_ann = var_ann (mem);
-
- gcc_assert (m_ann->mem_tag_kind == TYPE_TAG);
+ gcc_assert (TREE_CODE (mem) == SYMBOL_MEMORY_TAG);
- alias_stats.tbaa_queries++;
-
- /* If the alias sets don't conflict then MEM cannot alias VAR. */
- if (!alias_sets_conflict_p (mem_alias_set, var_alias_set))
+ if (!DECL_NO_TBAA_P (ptr))
{
- alias_stats.alias_noalias++;
- alias_stats.tbaa_resolved++;
- return false;
- }
+ alias_stats.tbaa_queries++;
- /* If var is a record or union type, ptr cannot point into var
- unless there is some operation explicit address operation in the
- program that can reference a field of the ptr's dereferenced
- type. 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 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;
+ }
- if ((mem_alias_set != 0) && (var_alias_set != 0))
- {
- tree ptr_type = TREE_TYPE (ptr);
- tree var_type = TREE_TYPE (var);
-
- /* The star count is -1 if the type at the end of the pointer_to
- chain is not a record or union type. */
- if ((!alias_set_only) &&
- ipa_type_escape_star_count_of_interesting_type (var_type) >= 0)
+ /* If 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)
{
- int ptr_star_count = 0;
-
- /* Ipa_type_escape_star_count_of_interesting_type is a little to
- 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. */
+ 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)
{
- ptr_type = TREE_TYPE (ptr_type);
- ptr_star_count++;
- }
+ int ptr_star_count = 0;
- /* There does not appear to be a better test to see if the
- pointer type was one of the pointer to everything
- types. */
+ /* 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++;
+ }
- if (ptr_star_count > 0)
- {
- alias_stats.structnoaddress_queries++;
- if (ipa_type_escape_field_does_not_clobber_p (var_type,
- TREE_TYPE (ptr)))
+ /* There does not appear to be a better test to see if
+ the pointer type was one of the pointer to everything
+ types. */
+ if (ptr_star_count > 0)
+ {
+ alias_stats.structnoaddress_queries++;
+ if (ipa_type_escape_field_does_not_clobber_p (var_type,
+ TREE_TYPE (ptr)))
+ {
+ alias_stats.structnoaddress_resolved++;
+ alias_stats.alias_noalias++;
+ return false;
+ }
+ }
+ else if (ptr_star_count == 0)
{
+ /* If PTR_TYPE was not really a pointer to type, it cannot
+ alias. */
+ alias_stats.structnoaddress_queries++;
alias_stats.structnoaddress_resolved++;
alias_stats.alias_noalias++;
return false;
}
}
- else if (ptr_star_count == 0)
- {
- /* If ptr_type was not really a pointer to type, it cannot
- alias. */
- alias_stats.structnoaddress_queries++;
- alias_stats.structnoaddress_resolved++;
- alias_stats.alias_noalias++;
- return false;
- }
}
}
static void
add_may_alias (tree var, tree alias)
{
- size_t i;
- var_ann_t v_ann = get_var_ann (var);
- var_ann_t a_ann = get_var_ann (alias);
-
/* Don't allow self-referential aliases. */
gcc_assert (var != alias);
gcc_assert (may_be_aliased (alias));
#endif
- if (v_ann->may_aliases == NULL)
- VARRAY_TREE_INIT (v_ann->may_aliases, 2, "aliases");
-
- /* Avoid adding duplicates. */
- for (i = 0; i < VARRAY_ACTIVE_SIZE (v_ann->may_aliases); i++)
- if (alias == VARRAY_TREE (v_ann->may_aliases, i))
- return;
-
- /* If VAR is a call-clobbered variable, so is its new ALIAS.
- FIXME, call-clobbering should only depend on whether an address
- escapes. It should be independent of aliasing. */
- if (is_call_clobbered (var))
- mark_call_clobbered (alias);
-
- /* Likewise. If ALIAS is call-clobbered, so is VAR. */
- else if (is_call_clobbered (alias))
- mark_call_clobbered (var);
-
- VARRAY_PUSH_TREE (v_ann->may_aliases, alias);
- a_ann->is_alias_tag = 1;
-}
-
-
-/* Replace alias I in the alias sets of VAR with NEW_ALIAS. */
-
-static void
-replace_may_alias (tree var, size_t i, tree new_alias)
-{
- var_ann_t v_ann = var_ann (var);
- VARRAY_TREE (v_ann->may_aliases, i) = new_alias;
-
- /* If VAR is a call-clobbered variable, so is NEW_ALIAS.
- FIXME, call-clobbering should only depend on whether an address
- escapes. It should be independent of aliasing. */
- if (is_call_clobbered (var))
- mark_call_clobbered (new_alias);
+ /* VAR must be a symbol or a name tag. */
+ gcc_assert (TREE_CODE (var) == SYMBOL_MEMORY_TAG
+ || TREE_CODE (var) == NAME_MEMORY_TAG);
- /* Likewise. If NEW_ALIAS is call-clobbered, so is VAR. */
- else if (is_call_clobbered (new_alias))
- mark_call_clobbered (var);
+ if (MTAG_ALIASES (var) == NULL)
+ MTAG_ALIASES (var) = BITMAP_ALLOC (&alias_bitmap_obstack);
+
+ bitmap_set_bit (MTAG_ALIASES (var), DECL_UID (alias));
}
3- STMT is an assignment to a non-local variable, or
4- STMT is a return statement.
- AI points to the alias information collected so far. */
+ Return the type of escape site found, if we found one, or NO_ESCAPE
+ if none. */
-bool
-is_escape_site (tree stmt, struct alias_info *ai)
+enum escape_type
+is_escape_site (tree stmt)
{
tree call = get_call_expr_in (stmt);
if (call != NULL_TREE)
{
- ai->num_calls_found++;
-
if (!TREE_SIDE_EFFECTS (call))
- ai->num_pure_const_calls_found++;
+ return ESCAPE_TO_PURE_CONST;
- return true;
+ return ESCAPE_TO_CALL;
}
else if (TREE_CODE (stmt) == ASM_EXPR)
- return true;
- else if (TREE_CODE (stmt) == MODIFY_EXPR)
+ return ESCAPE_TO_ASM;
+ else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
{
- tree lhs = TREE_OPERAND (stmt, 0);
+ tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
/* Get to the base of _REF nodes. */
if (TREE_CODE (lhs) != SSA_NAME)
/* If we couldn't recognize the LHS of the assignment, assume that it
is a non-local store. */
if (lhs == NULL_TREE)
- return true;
-
- /* If the RHS is a conversion between a pointer and an integer, the
- pointer escapes since we can't track the integer. */
- if ((TREE_CODE (TREE_OPERAND (stmt, 1)) == NOP_EXPR
- || TREE_CODE (TREE_OPERAND (stmt, 1)) == CONVERT_EXPR
- || TREE_CODE (TREE_OPERAND (stmt, 1)) == VIEW_CONVERT_EXPR)
- && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND
- (TREE_OPERAND (stmt, 1), 0)))
- && !POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (stmt, 1))))
- return true;
+ 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 false;
+ 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
Midkiff, ``Escape analysis for java,'' in Proceedings of the
Conference on Object-Oriented Programming Systems, Languages, and
Applications (OOPSLA), pp. 1-19, 1999. */
- return true;
+ return ESCAPE_STORED_IN_GLOBAL;
}
else if (TREE_CODE (stmt) == RETURN_EXPR)
- return true;
+ return ESCAPE_TO_RETURN;
- return false;
+ 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
static tree
create_memory_tag (tree type, bool is_type_tag)
{
- var_ann_t ann;
- tree tag = create_tmp_var_raw (type, (is_type_tag) ? "TMT" : "NMT");
+ 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. */
/* Memory tags are by definition addressable. */
TREE_ADDRESSABLE (tag) = 1;
- ann = get_var_ann (tag);
- ann->mem_tag_kind = (is_type_tag) ? TYPE_TAG : NAME_TAG;
- ann->type_mem_tag = NULL_TREE;
+ set_symbol_mem_tag (tag, NULL_TREE);
/* Add the tag to the symbol table. */
- add_referenced_tmp_var (tag);
+ add_referenced_var (tag);
return tag;
}
if (tag == NULL_TREE)
tag = create_memory_tag (TREE_TYPE (TREE_TYPE (ptr)), false);
-
- /* If PTR is a PARM_DECL, it points to a global variable or malloc,
- then its name tag should be considered a global variable. */
- if (TREE_CODE (SSA_NAME_VAR (ptr)) == PARM_DECL
- || pi->pt_global_mem)
- mark_call_clobbered (tag);
-
return tag;
}
-/* Return the type 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.
+/* 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. */
+ AI points to the data gathered during alias analysis. This
+ function populates the array AI->POINTERS. */
static tree
-get_tmt_for (tree ptr, struct alias_info *ai)
+get_smt_for (tree ptr, struct alias_info *ai)
{
size_t i;
tree tag;
tree tag_type = TREE_TYPE (TREE_TYPE (ptr));
- HOST_WIDE_INT tag_set = get_alias_set (tag_type);
+ alias_set_type tag_set = get_alias_set (tag_type);
+
+ /* We use a unique memory tag for all the ref-all pointers. */
+ if (PTR_IS_REF_ALL (ptr))
+ {
+ 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
for (i = 0, tag = NULL_TREE; i < ai->num_pointers; i++)
{
struct alias_map_d *curr = ai->pointers[i];
- tree curr_tag = var_ann (curr->var)->type_mem_tag;
- if (tag_set == curr->set
- && TYPE_READONLY (tag_type) == TYPE_READONLY (TREE_TYPE (curr_tag)))
+ tree curr_tag = symbol_mem_tag (curr->var);
+ if (tag_set == curr->set)
{
tag = curr_tag;
break;
{
struct alias_map_d *alias_map;
- /* If PTR did not have a type tag already, create a new TMT.*
+ /* If PTR did not have a symbol tag already, create a new SMT.*
artificial variable representing the memory location
pointed-to by PTR. */
- if (var_ann (ptr)->type_mem_tag == NULL_TREE)
+ tag = symbol_mem_tag (ptr);
+ if (tag == NULL_TREE)
tag = create_memory_tag (tag_type, true);
- else
- tag = var_ann (ptr)->type_mem_tag;
/* 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 = xcalloc (1, sizeof (*alias_map));
+ 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 type tag has the same alias set as the
+ /* Make sure that the symbol tag has the same alias set as the
pointed-to type. */
gcc_assert (tag_set == get_alias_set (tag));
- /* If PTR's pointed-to type is read-only, then TAG's type must also
- be read-only. */
- gcc_assert (TYPE_READONLY (tag_type) == TYPE_READONLY (TREE_TYPE (tag)));
-
return tag;
}
static void
create_global_var (void)
{
- global_var = build_decl (VAR_DECL, get_identifier (".GLOBAL_VAR"),
- void_type_node);
+ 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_THIS_VOLATILE (global_var) = 0;
TREE_ADDRESSABLE (global_var) = 0;
- add_referenced_tmp_var (global_var);
+ 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;
}
referenced_var_iterator rvi;
tree var;
+ fprintf (file, "\nAlias information for %s\n\n", funcname);
+
+ dump_memory_partitions (file);
+
fprintf (file, "\nFlow-insensitive alias information for %s\n\n", funcname);
fprintf (file, "Aliased symbols\n\n");
fprintf (file, "\nDereferenced pointers\n\n");
FOR_EACH_REFERENCED_VAR (var, rvi)
- {
- var_ann_t ann = var_ann (var);
- if (ann->type_mem_tag)
- dump_variable (file, var);
- }
+ if (symbol_mem_tag (var))
+ dump_variable (file, var);
- fprintf (file, "\nType memory tags\n\n");
+ fprintf (file, "\nSymbol memory tags\n\n");
FOR_EACH_REFERENCED_VAR (var, rvi)
{
- var_ann_t ann = var_ann (var);
- if (ann->mem_tag_kind == TYPE_TAG)
+ if (TREE_CODE (var) == SYMBOL_MEMORY_TAG)
dump_variable (file, var);
}
FOR_EACH_REFERENCED_VAR (var, rvi)
{
- var_ann_t ann = var_ann (var);
- if (ann->mem_tag_kind == NAME_TAG)
+ if (TREE_CODE (var) == NAME_MEMORY_TAG)
dump_variable (file, var);
}
pi = SSA_NAME_PTR_INFO (t);
if (pi == NULL)
{
- pi = ggc_alloc (sizeof (*pi));
- memset ((void *)pi, 0, sizeof (*pi));
+ pi = GGC_CNEW (struct ptr_info_def);
SSA_NAME_PTR_INFO (t) = pi;
}
if (pi->pt_vars)
{
- unsigned ix;
- bitmap_iterator bi;
-
- fprintf (file, ", points-to vars: { ");
- EXECUTE_IF_SET_IN_BITMAP (pi->pt_vars, 0, ix, bi)
- {
- print_generic_expr (file, referenced_var (ix), dump_flags);
- fprintf (file, " ");
- }
- fprintf (file, "}");
+ fprintf (file, ", points-to vars: ");
+ dump_decl_set (file, pi->pt_vars);
}
}
{
if (POINTER_TYPE_P (TREE_TYPE (var)))
{
- tree def = default_def (var);
+ tree def = gimple_default_def (cfun, var);
if (def)
dump_points_to_info_for (file, def);
}
tree stmt = bsi_stmt (si);
tree def;
FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
- if (POINTER_TYPE_P (TREE_TYPE (def)))
+ if (TREE_CODE (def) == SSA_NAME
+ && POINTER_TYPE_P (TREE_TYPE (def)))
dump_points_to_info_for (file, def);
}
}
void
dump_may_aliases_for (FILE *file, tree var)
{
- varray_type aliases;
+ bitmap aliases;
- if (TREE_CODE (var) == SSA_NAME)
- var = SSA_NAME_VAR (var);
-
- aliases = var_ann (var)->may_aliases;
+ aliases = MTAG_ALIASES (var);
if (aliases)
{
- size_t i;
+ bitmap_iterator bi;
+ unsigned int i;
+ tree al;
+
fprintf (file, "{ ");
- for (i = 0; i < VARRAY_ACTIVE_SIZE (aliases); i++)
+ EXECUTE_IF_SET_IN_BITMAP (aliases, 0, i, bi)
{
- print_generic_expr (file, VARRAY_TREE (aliases, i), dump_flags);
+ al = referenced_var (i);
+ print_generic_expr (file, al, dump_flags);
fprintf (file, " ");
}
fprintf (file, "}");
dump_may_aliases_for (stderr, var);
}
+
/* Return true if VAR may be aliased. */
bool
/* Globally visible variables can have their addresses taken by other
translation units. */
- if (DECL_EXTERNAL (var) || TREE_PUBLIC (var))
+ if (MTAG_P (var)
+ && (MTAG_GLOBAL (var) || TREE_PUBLIC (var)))
+ return true;
+ else if (!MTAG_P (var)
+ && (DECL_EXTERNAL (var) || TREE_PUBLIC (var)))
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. */
+ /* 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 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 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)
return false;
+
if (decl_function_context (var) == current_function_decl)
return false;
return true;
}
+/* 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). */
-/* Given two symbols return TRUE if one is in the alias set of the other. */
-bool
-is_aliased_with (tree tag, tree sym)
+static tree
+add_may_alias_for_new_tag (tree tag, tree var)
{
- size_t i;
- varray_type aliases;
+ bitmap aliases = NULL;
+
+ if (MTAG_P (var))
+ aliases = may_aliases (var);
- if (var_ann (sym)->is_alias_tag)
+ /* Case 1: |aliases| == 1 */
+ if (aliases
+ && bitmap_single_bit_set_p (aliases))
{
- aliases = var_ann (tag)->may_aliases;
-
- if (aliases == NULL)
- return false;
-
- for (i = 0; i < VARRAY_ACTIVE_SIZE (aliases); i++)
- if (VARRAY_TREE (aliases, i) == sym)
- return true;
+ tree ali = referenced_var (bitmap_first_set_bit (aliases));
+ if (TREE_CODE (ali) == SYMBOL_MEMORY_TAG)
+ return ali;
}
+
+ /* Case 2: |aliases| == 0 */
+ if (aliases == NULL)
+ add_may_alias (tag, var);
else
{
- aliases = var_ann (sym)->may_aliases;
-
- if (aliases == NULL)
- return false;
-
- for (i = 0; i < VARRAY_ACTIVE_SIZE (aliases); i++)
- if (VARRAY_TREE (aliases, i) == tag)
- return true;
+ /* Case 3: |aliases| > 1 */
+ union_alias_set_into (tag, aliases);
}
-
- return false;
+ 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.
-/* Add VAR to the list of may-aliases of PTR's type tag. If PTR
- doesn't already have a type tag, create one. */
+ Note, the set of aliases represented by the new symbol tag are not marked
+ for renaming. */
void
-add_type_alias (tree ptr, tree var)
+new_type_alias (tree ptr, tree var, tree expr)
{
- varray_type aliases;
+ tree tag_type = TREE_TYPE (TREE_TYPE (ptr));
tree tag;
- var_ann_t ann = var_ann (ptr);
subvar_t svars;
- VEC (tree, heap) *varvec = NULL;
-
- if (ann->type_mem_tag == NULL_TREE)
- {
- tree q = NULL_TREE;
- tree tag_type = TREE_TYPE (TREE_TYPE (ptr));
- HOST_WIDE_INT tag_set = get_alias_set (tag_type);
- safe_referenced_var_iterator rvi;
-
- /* PTR doesn't have a type tag, create a new one and add VAR to
- the new tag's alias set.
+ tree ali = NULL_TREE;
+ HOST_WIDE_INT offset, size, maxsize;
+ tree ref;
+ VEC (tree, heap) *overlaps = NULL;
+ unsigned int len, i;
+ tree subvar;
- FIXME, This is slower than necessary. We need to determine
- whether there is another pointer Q with the same alias set as
- PTR. This could be sped up by having type tags associated
- with types. */
- FOR_EACH_REFERENCED_VAR_SAFE (q, varvec, rvi)
- {
- if (POINTER_TYPE_P (TREE_TYPE (q))
- && tag_set == get_alias_set (TREE_TYPE (TREE_TYPE (q))))
- {
- /* Found another pointer Q with the same alias set as
- the PTR's pointed-to type. If Q has a type tag, use
- it. Otherwise, create a new memory tag for PTR. */
- var_ann_t ann1 = var_ann (q);
- if (ann1->type_mem_tag)
- ann->type_mem_tag = ann1->type_mem_tag;
- else
- ann->type_mem_tag = create_memory_tag (tag_type, true);
- goto found_tag;
- }
- }
- /* Couldn't find any other pointer with a type tag we could use.
- Create a new memory tag for PTR. */
- ann->type_mem_tag = create_memory_tag (tag_type, true);
- }
+ gcc_assert (symbol_mem_tag (ptr) == NULL_TREE);
+ gcc_assert (!MTAG_P (var));
-found_tag:
- /* If VAR is not already PTR's type tag, add it to the may-alias set
- for PTR's type tag. */
- gcc_assert (var_ann (var)->type_mem_tag == NOT_A_TAG);
- tag = ann->type_mem_tag;
+ ref = get_ref_base_and_extent (expr, &offset, &size, &maxsize);
+ gcc_assert (ref);
- /* If VAR has subvars, add the subvars to the tag instead of the
- actual var. */
- if (var_can_have_subvars (var)
- && (svars = get_subvars_for_var (var)))
- {
- subvar_t sv;
- for (sv = svars; sv; sv = sv->next)
- add_may_alias (tag, sv->var);
- }
- else
- add_may_alias (tag, var);
+ tag = create_memory_tag (tag_type, true);
+ set_symbol_mem_tag (ptr, tag);
- /* TAG and its set of aliases need to be marked for renaming. */
- mark_sym_for_renaming (tag);
- if ((aliases = var_ann (tag)->may_aliases) != NULL)
+ /* 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)))
{
- size_t i;
- for (i = 0; i < VARRAY_ACTIVE_SIZE (aliases); i++)
- mark_sym_for_renaming (VARRAY_TREE (aliases, i));
- }
+ for (i = 0; VEC_iterate (tree, svars, i, subvar); ++i)
+ {
+ bool exact;
- /* If we had grouped aliases, VAR may have aliases of its own. Mark
- them for renaming as well. Other statements referencing the
- aliases of VAR will need to be updated. */
- if ((aliases = var_ann (var)->may_aliases) != NULL)
- {
- size_t i;
- for (i = 0; i < VARRAY_ACTIVE_SIZE (aliases); i++)
- mark_sym_for_renaming (VARRAY_TREE (aliases, i));
+ if (overlap_subvar (offset, maxsize, subvar, &exact))
+ VEC_safe_push (tree, heap, overlaps, subvar);
+ }
+ gcc_assert (overlaps != NULL);
}
- VEC_free (tree, heap, varvec);
-}
-
-
-/* Create a new type tag for PTR. Construct the may-alias list of this type
- tag so that it has the aliasing of VAR.
-
- Note, the set of aliases represented by the new type tag are not marked
- for renaming. */
-
-void
-new_type_alias (tree ptr, tree var)
-{
- var_ann_t p_ann = var_ann (ptr);
- tree tag_type = TREE_TYPE (TREE_TYPE (ptr));
- var_ann_t v_ann = var_ann (var);
- tree tag;
- subvar_t svars;
-
- gcc_assert (p_ann->type_mem_tag == NULL_TREE);
- gcc_assert (v_ann->mem_tag_kind == NOT_A_TAG);
-
- /* Add VAR to the may-alias set of PTR's new type tag. If VAR has
- subvars, add the subvars to the tag instead of the actual var. */
- if (var_can_have_subvars (var)
- && (svars = get_subvars_for_var (var)))
+ else if (var_can_have_subvars (var)
+ && (svars = get_subvars_for_var (var)))
{
- subvar_t sv;
-
- tag = create_memory_tag (tag_type, true);
- p_ann->type_mem_tag = tag;
-
- for (sv = svars; sv; sv = sv->next)
- add_may_alias (tag, sv->var);
+ /* 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 (i = 0; VEC_iterate (tree, svars, i, subvar); ++i)
+ VEC_safe_push (tree, heap, overlaps, subvar);
+
+ gcc_assert (overlaps != NULL);
}
else
+ ali = add_may_alias_for_new_tag (tag, var);
+
+ len = VEC_length (tree, overlaps);
+ if (len > 0)
{
- /* 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. */
- varray_type aliases = v_ann->may_aliases;
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "\nnumber of overlapping subvars = %u\n", len);
- if ((aliases != NULL)
- && (VARRAY_ACTIVE_SIZE (aliases) == 1))
+ if (len == 1)
+ ali = add_may_alias_for_new_tag (tag, VEC_index (tree, overlaps, 0));
+ else if (len > 1)
{
- tree ali = VARRAY_TREE (aliases, 0);
+ unsigned int k;
+ tree sv_var;
- if (get_var_ann (ali)->mem_tag_kind == TYPE_TAG)
+ for (k = 0; VEC_iterate (tree, overlaps, k, sv_var); k++)
{
- p_ann->type_mem_tag = ali;
- return;
+ ali = add_may_alias_for_new_tag (tag, sv_var);
+
+ 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);
+ }
- tag = create_memory_tag (tag_type, true);
- p_ann->type_mem_tag = tag;
-
- if (aliases == NULL)
- add_may_alias (tag, var);
- else
- {
- size_t i;
-
- for (i = 0; i < VARRAY_ACTIVE_SIZE (aliases); i++)
- add_may_alias (tag, VARRAY_TREE (aliases, i));
- }
- }
+ set_symbol_mem_tag (ptr, ali);
+ TREE_READONLY (tag) = TREE_READONLY (var);
+ MTAG_GLOBAL (tag) = is_global_var (var);
}
-
-
/* This represents the used range of a variable. */
typedef struct used_part
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 int
used_part_map_eq (const void *va, const void *vb)
{
- const struct used_part_map *a = va, *b = 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);
}
{
struct used_part_map *h, in;
in.uid = uid;
- h = htab_find_with_hash (used_portions, &in, uid);
+ h = (struct used_part_map *) htab_find_with_hash (used_portions, &in, uid);
if (!h)
return NULL;
return h->to;
struct used_part_map *h;
void **loc;
- h = xmalloc (sizeof (struct used_part_map));
+ h = XNEW (struct used_part_map);
h->uid = uid;
h->to = to;
loc = htab_find_slot_with_hash (used_portions, h,
used_part_t up;
if ((up = up_lookup (uid)) == NULL)
{
- up = xcalloc (1, sizeof (struct used_part));
+ up = XCNEW (struct used_part);
up->minused = INT_MAX;
up->maxused = 0;
up->explicit_uses = false;
up->implicit_uses = false;
+ up->write_only = true;
}
return up;
}
-/* Create and return a structure sub-variable for field FIELD of
- variable VAR. */
+/* Create and return a structure sub-variable for field type FIELD at
+ offset OFFSET, with size SIZE, of variable VAR. If ALIAS_SET not
+ -1 this field is non-addressable and we should use this alias set
+ with this field. */
static tree
-create_sft (tree var, tree field)
+create_sft (tree var, tree field, unsigned HOST_WIDE_INT offset,
+ unsigned HOST_WIDE_INT size, alias_set_type alias_set,
+ bool base_for_components)
{
- var_ann_t ann;
- tree subvar = create_tmp_var_raw (TREE_TYPE (field), "SFT");
+ 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);
- DECL_EXTERNAL (subvar) = DECL_EXTERNAL (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. */
- ann = get_var_ann (subvar);
- ann->mem_tag_kind = STRUCT_FIELD;
- ann->type_mem_tag = NULL;
- add_referenced_tmp_var (subvar);
+ set_symbol_mem_tag (subvar, NULL);
+ add_referenced_var (subvar);
+ SFT_PARENT_VAR (subvar) = var;
+ SFT_OFFSET (subvar) = offset;
+ SFT_SIZE (subvar) = size;
+ SFT_ALIAS_SET (subvar) = alias_set;
+ SFT_BASE_FOR_COMPONENTS_P (subvar) = base_for_components;
+ SFT_UNPARTITIONABLE_P (subvar) = false;
return subvar;
}
used_part_t up;
size_t uid = DECL_UID (var);
- if (!up_lookup (uid))
+ up = up_lookup (uid);
+ if (!up
+ || up->write_only)
return;
- up = up_lookup (uid);
- push_fields_onto_fieldstack (TREE_TYPE (var), &fieldstack, 0, NULL);
- if (VEC_length (fieldoff_s, fieldstack) != 0)
+ push_fields_onto_fieldstack (TREE_TYPE (var), &fieldstack, 0, NULL,
+ TREE_TYPE (var));
+ /* Make sure to not create SFTs for structs we won't generate variable
+ infos for. See tree-ssa-structalias.c:create_variable_info_for (). */
+ if (VEC_length (fieldoff_s, fieldstack) > 1
+ && VEC_length (fieldoff_s, fieldstack) <= MAX_FIELDS_FOR_FIELD_SENSITIVE)
{
subvar_t *subvars;
fieldoff_s *fo;
for (i = 0; VEC_iterate (fieldoff_s, fieldstack, i, fo); i++)
{
- if (!DECL_SIZE (fo->field)
- || TREE_CODE (DECL_SIZE (fo->field)) != INTEGER_CST
- || TREE_CODE (TREE_TYPE (fo->field)) == ARRAY_TYPE
+ if (!fo->size
+ || TREE_CODE (fo->size) != INTEGER_CST
|| fo->offset < 0)
{
notokay = true;
/* Otherwise, create the variables. */
subvars = lookup_subvars_for_var (var);
-
+ *subvars = VEC_alloc (tree, gc, VEC_length (fieldoff_s, fieldstack));
+
sort_fieldstack (fieldstack);
- for (i = VEC_length (fieldoff_s, fieldstack);
- VEC_iterate (fieldoff_s, fieldstack, --i, fo);)
+ for (i = 0; VEC_iterate (fieldoff_s, fieldstack, i, fo); ++i)
{
- subvar_t sv;
HOST_WIDE_INT fosize;
- tree currfotype;
+ tree currfotype, subvar;
- fosize = TREE_INT_CST_LOW (DECL_SIZE (fo->field));
- currfotype = TREE_TYPE (fo->field);
+ fosize = TREE_INT_CST_LOW (fo->size);
+ currfotype = fo->type;
/* If this field isn't in the used portion,
or it has the exact same offset and size as the last
- field, skip it. */
-
- if (((fo->offset <= up->minused
- && fo->offset + fosize <= up->minused)
- || fo->offset >= up->maxused)
+ field, skip it. Note that we always need the field at
+ offset 0 so we can properly handle pointers to the
+ structure. */
+
+ if ((fo->offset != 0
+ && ((fo->offset <= up->minused
+ && fo->offset + fosize <= up->minused)
+ || fo->offset >= up->maxused))
|| (fo->offset == lastfooffset
&& fosize == lastfosize
&& currfotype == lastfotype))
continue;
- sv = ggc_alloc (sizeof (struct subvar));
- sv->offset = fo->offset;
- sv->size = fosize;
- sv->next = *subvars;
- sv->var = create_sft (var, fo->field);
+ subvar = create_sft (var, fo->type, fo->offset,
+ fosize, fo->alias_set, fo->base_for_components);
+ VEC_quick_push (tree, *subvars, subvar);
if (dump_file)
{
fprintf (dump_file, "structure field tag %s created for var %s",
- get_name (sv->var), get_name (var));
+ get_name (subvar), get_name (var));
fprintf (dump_file, " offset " HOST_WIDE_INT_PRINT_DEC,
- sv->offset);
+ SFT_OFFSET (subvar));
fprintf (dump_file, " size " HOST_WIDE_INT_PRINT_DEC,
- sv->size);
+ SFT_SIZE (subvar));
fprintf (dump_file, "\n");
}
lastfotype = currfotype;
lastfooffset = fo->offset;
lastfosize = fosize;
- *subvars = sv;
}
/* Once we have created subvars, the original is no longer call
entire structure. */
static tree
-find_used_portions (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
+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 offset;
- enum machine_mode mode;
- int unsignedp;
- int volatilep;
tree ref;
- ref = get_inner_reference (*tp, &bitsize, &bitpos, &offset, &mode,
- &unsignedp, &volatilep, false);
- if (DECL_P (ref) && offset == NULL && bitsize != -1)
- {
+ 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;
if (bitpos <= up->minused)
up->minused = bitpos;
- if ((bitpos + bitsize >= up->maxused))
- up->maxused = bitpos + bitsize;
-
- up->explicit_uses = true;
+ 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;
}
- else if (DECL_P (ref))
- {
- if (DECL_SIZE (ref)
- && var_can_have_subvars (ref)
- && TREE_CODE (DECL_SIZE (ref)) == INTEGER_CST)
- {
- used_part_t up;
- size_t uid = DECL_UID (ref);
-
- up = get_or_create_used_part_for (uid);
-
- up->minused = 0;
- up->maxused = TREE_INT_CST_LOW (DECL_SIZE (ref));
-
- up->implicit_uses = true;
-
- 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
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;
}
}
break;
+ case CALL_EXPR:
+ {
+ int i;
+ int nargs = call_expr_nargs (*tp);
+ for (i = 0; i < nargs; i++)
+ {
+ tree *arg = &CALL_EXPR_ARG (*tp, i);
+ if (TREE_CODE (*arg) == ADDR_EXPR)
+ find_used_portions (arg, walk_subtrees, NULL);
+ }
+ *walk_subtrees = 0;
+ return NULL_TREE;
+ }
case VAR_DECL:
case PARM_DECL:
+ case RESULT_DECL:
{
tree var = *tp;
if (DECL_SIZE (var)
/* Create structure field variables for structures used in this function. */
-static void
+static unsigned int
create_structure_vars (void)
{
basic_block bb;
FOR_EACH_BB (bb)
{
block_stmt_iterator bsi;
+ tree phi;
+
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ {
+ use_operand_p use;
+ ssa_op_iter iter;
+
+ FOR_EACH_PHI_ARG (use, phi, iter, SSA_OP_USE)
+ {
+ tree op = USE_FROM_PTR (use);
+ walk_tree_without_duplicates (&op, find_used_portions,
+ NULL);
+ }
+ }
+
for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
{
walk_tree_without_duplicates (bsi_stmt_ptr (bsi),
if (var
&& DECL_SIZE (var)
&& var_can_have_subvars (var)
- && var_ann (var)->mem_tag_kind == NOT_A_TAG
+ && !MTAG_P (var)
&& TREE_CODE (DECL_SIZE (var)) == INTEGER_CST)
create_overlap_variables_for (var);
}
htab_delete (used_portions);
VEC_free (tree, heap, varvec);
+ /* 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;
+
+ if (STORED_SYMS (stmt))
+ EXECUTE_IF_SET_IN_BITMAP (STORED_SYMS (stmt), 0, i, bi)
+ {
+ tree sym = referenced_var_lookup (i);
+ if (get_subvars_for_var (sym))
+ {
+ update = true;
+ break;
+ }
+ }
+
+ 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 (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;
+ }
+ }
+
+ if (update)
+ update_stmt (stmt);
+ }
+ }
+
+ return TODO_rebuild_alias;
}
static bool
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. */
+
+static unsigned int
+reset_cc_flags (void)
+{
+ tree var;
+ referenced_var_iterator rvi;
+
+ FOR_EACH_REFERENCED_VAR (var, rvi)
+ var_ann (var)->call_clobbered = false;
+ return 0;
+}
+
+struct tree_opt_pass pass_reset_cc_flags =
+{
+ 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 */
+};
+
+static bool
+gate_build_alias (void)
+{
+ return !gate_structure_vars();
+}
+
+
+struct tree_opt_pass pass_build_alias =
+{
+ "build_alias", /* name */
+ gate_build_alias, /* gate */
+ NULL, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ 0, /* tv_id */
+ PROP_cfg | PROP_ssa, /* properties_required */
+ PROP_alias, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_rebuild_alias, /* todo_flags_finish */
+ 0 /* letter */
+};
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