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When trying to skip a virtual PHI during an alias walk we have to direct a possible VN translation hook to not use valueization when walking a backedge. But this backedge detection was overly optimistic, not honoring irreducible regions. The following hookizes the backedge detection so VN can properly flag edges that are back with respect to its particular CFG traversal. PR tree-optimization/123298 * tree-ssa-alias.h (get_continuation_for_phi): Take a gphi *, add is_backedge hook argument. (walk_non_aliased_vuses): Add is_backedge hook argument. * tree-ssa-alias.cc (maybe_skip_until): Adjust. (get_continuation_for_phi): Use new hook to classify an edge into the PHI as backedge. (walk_non_aliased_vuses): Adjust. * gimple-lower-bitint.cc (bitint_dom_walker::before_dom_children): Likewise. * ipa-prop.cc (determine_known_aggregate_parts): Likewise. * tree-ssa-scopedtables.cc (avail_exprs_stack::lookup_avail_expr): Likewise. * tree-ssa-pre.cc (translate_vuse_through_block): Likewise. * tree-ssa-sccvn.cc (vn_bb_to_rpo): Make BB to RPO order mapping accessible from new hook. (do_rpo_vn_1): Likewise. (vn_is_backedge): New hook to classify edge. (vn_reference_lookup_pieces): Adjust. (vn_reference_lookup): Likewise. * gcc.dg/torture/pr123298.c: New testcase.
223 lines
8.1 KiB
C++
223 lines
8.1 KiB
C++
/* Tree based alias analysis and alias oracle.
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Copyright (C) 2008-2026 Free Software Foundation, Inc.
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Contributed by Richard Guenther <rguenther@suse.de>
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#ifndef TREE_SSA_ALIAS_H
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#define TREE_SSA_ALIAS_H
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/* The points-to solution.
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The points-to solution is a union of pt_vars and the abstract
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sets specified by the flags. */
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struct GTY(()) pt_solution
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{
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/* Nonzero if points-to analysis couldn't determine where this pointer
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is pointing to. */
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unsigned int anything : 1;
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/* Nonzero if the points-to set includes any global memory. Note that
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even if this is zero pt_vars can still include global variables. */
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unsigned int nonlocal : 1;
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/* Nonzero if the points-to set includes the local escaped solution by
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reference. */
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unsigned int escaped : 1;
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/* Nonzero if the points-to set includes the IPA escaped solution by
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reference. */
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unsigned int ipa_escaped : 1;
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/* Nonzero if the points-to set includes 'nothing', the points-to set
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includes memory at address NULL. */
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unsigned int null : 1;
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/* Nonzero if the points-to set includes a readonly object like a
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STRING_CST that does not have an underlying declaration but will
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end up in the constant pool. */
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unsigned int const_pool : 1;
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/* Nonzero if the vars bitmap includes a variable included in 'nonlocal'. */
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unsigned int vars_contains_nonlocal : 1;
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/* Nonzero if the vars bitmap includes a variable included in 'escaped'. */
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unsigned int vars_contains_escaped : 1;
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/* Nonzero if the vars bitmap includes a anonymous heap variable that
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escaped the function and thus became global. */
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unsigned int vars_contains_escaped_heap : 1;
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/* Nonzero if the vars bitmap includes a anonymous variable used to
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represent storage pointed to by a restrict qualified pointer. */
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unsigned int vars_contains_restrict : 1;
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/* Nonzero if the vars bitmap includes an interposable variable. */
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unsigned int vars_contains_interposable : 1;
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/* Set of variables that this pointer may point to. */
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bitmap vars;
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};
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/* Simplified and cached information about a memory reference tree.
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Used by the alias-oracle internally and externally in alternate
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interfaces. */
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class ao_ref
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{
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public:
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/* The original full memory reference tree or NULL_TREE if that is
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not available. */
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tree ref;
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/* The following fields are the decomposed reference as returned
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by get_ref_base_and_extent. */
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/* The base object of the memory reference or NULL_TREE if all of
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the following fields are not yet computed. */
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tree base;
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/* The offset relative to the base. */
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poly_int64 offset;
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/* The size of the access. */
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poly_int64 size;
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/* The maximum possible extent of the access or -1 if unconstrained. */
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poly_int64 max_size;
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/* The alias set of the access or -1 if not yet computed. */
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alias_set_type ref_alias_set;
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/* The alias set of the base object or -1 if not yet computed. */
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alias_set_type base_alias_set;
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/* Whether the memory is considered a volatile access. */
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bool volatile_p;
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bool max_size_known_p () const;
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};
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/* Return true if the maximum size is known, rather than the special -1
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marker. */
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inline bool
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ao_ref::max_size_known_p () const
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{
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return known_size_p (max_size);
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}
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/* In tree-ssa-alias.cc */
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extern void ao_ref_init (ao_ref *, tree);
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extern void ao_ref_init_from_ptr_and_size (ao_ref *, tree, tree);
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extern void ao_ref_init_from_ptr_and_range (ao_ref *, tree, bool,
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poly_int64, poly_int64,
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poly_int64);
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extern tree ao_ref_base (ao_ref *);
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extern alias_set_type ao_ref_alias_set (ao_ref *);
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extern alias_set_type ao_ref_base_alias_set (ao_ref *);
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extern tree ao_ref_alias_ptr_type (ao_ref *);
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extern tree ao_ref_base_alias_ptr_type (ao_ref *);
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extern bool ao_ref_alignment (ao_ref *, unsigned int *,
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unsigned HOST_WIDE_INT *);
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extern bool ptr_deref_may_alias_global_p (tree, bool);
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extern bool ptr_derefs_may_alias_p (tree, tree);
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extern bool ptrs_compare_unequal (tree, tree);
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extern bool ref_may_alias_global_p (tree, bool);
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extern bool ref_may_alias_global_p (ao_ref *, bool);
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extern bool refs_may_alias_p (tree, tree, bool = true);
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extern bool refs_may_alias_p_1 (ao_ref *, ao_ref *, bool);
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extern bool refs_anti_dependent_p (tree, tree);
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extern bool refs_output_dependent_p (tree, tree);
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extern bool ref_maybe_used_by_stmt_p (gimple *, tree, bool = true);
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extern bool ref_maybe_used_by_stmt_p (gimple *, ao_ref *, bool = true);
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extern bool stmt_may_clobber_global_p (gimple *, bool);
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extern bool stmt_may_clobber_ref_p (gimple *, tree, bool = true);
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extern bool stmt_may_clobber_ref_p_1 (gimple *, ao_ref *, bool = true);
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extern bool call_may_clobber_ref_p (gcall *, tree, bool = true);
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extern bool call_may_clobber_ref_p_1 (gcall *, ao_ref *, bool = true);
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extern bool stmt_kills_ref_p (gimple *, tree);
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extern bool stmt_kills_ref_p (gimple *, ao_ref *);
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extern bool ref_can_have_store_data_races (tree);
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enum translate_flags
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{ TR_TRANSLATE, TR_VALUEIZE_AND_DISAMBIGUATE, TR_DISAMBIGUATE };
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extern tree get_continuation_for_phi (gphi *, ao_ref *, bool,
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unsigned int &, bitmap *, bool,
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void *(*)(ao_ref *, tree, void *,
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translate_flags *),
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void *,
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bool (*)(edge, void *) = nullptr,
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translate_flags
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= TR_VALUEIZE_AND_DISAMBIGUATE);
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extern void *walk_non_aliased_vuses (ao_ref *, tree, bool,
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void *(*)(ao_ref *, tree, void *),
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void *(*)(ao_ref *, tree, void *,
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translate_flags *),
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bool (*)(edge, void *),
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tree (*)(tree), unsigned &, void *);
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extern int walk_aliased_vdefs (ao_ref *, tree,
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bool (*)(ao_ref *, tree, void *),
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void *, bitmap *,
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bool *function_entry_reached = NULL,
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unsigned int limit = 0);
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extern void dump_alias_info (FILE *);
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extern void debug_alias_info (void);
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extern void dump_points_to_solution (FILE *, struct pt_solution *);
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extern void debug (pt_solution &ref);
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extern void debug (pt_solution *ptr);
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extern void dump_points_to_info_for (FILE *, tree);
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extern void debug_points_to_info_for (tree);
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extern void dump_alias_stats (FILE *);
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/* In tree-ssa-structalias.cc */
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extern unsigned int compute_may_aliases (void);
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extern bool pt_solution_empty_p (const pt_solution *);
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extern bool pt_solution_singleton_or_null_p (struct pt_solution *, unsigned *);
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extern bool pt_solution_includes_global (struct pt_solution *, bool);
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extern bool pt_solution_includes (struct pt_solution *, const_tree);
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extern bool pt_solution_includes_const_pool (struct pt_solution *);
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extern bool pt_solutions_intersect (struct pt_solution *, struct pt_solution *);
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extern void pt_solution_reset (struct pt_solution *);
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extern void pt_solution_set (struct pt_solution *, bitmap, bool);
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extern void pt_solution_set_var (struct pt_solution *, tree);
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extern void dump_pta_stats (FILE *);
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extern GTY(()) struct pt_solution ipa_escaped_pt;
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/* Return true, if the two ranges [POS1, SIZE1] and [POS2, SIZE2]
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overlap. SIZE1 and/or SIZE2 can be (unsigned)-1 in which case the
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range is open-ended. Otherwise return false. */
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inline bool
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ranges_overlap_p (HOST_WIDE_INT pos1,
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unsigned HOST_WIDE_INT size1,
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HOST_WIDE_INT pos2,
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unsigned HOST_WIDE_INT size2)
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{
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if (size1 == 0 || size2 == 0)
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return false;
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if (pos1 >= pos2
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&& (size2 == (unsigned HOST_WIDE_INT)-1
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|| pos1 < (pos2 + (HOST_WIDE_INT) size2)))
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return true;
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if (pos2 >= pos1
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&& (size1 == (unsigned HOST_WIDE_INT)-1
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|| pos2 < (pos1 + (HOST_WIDE_INT) size1)))
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return true;
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return false;
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}
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#endif /* TREE_SSA_ALIAS_H */
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