/* Alias analysis for trees. Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. Contributed by Diego Novillo 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 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 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 COPYING3. If not see . */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "tree.h" #include "tm_p.h" #include "basic-block.h" #include "timevar.h" #include "expr.h" #include "ggc.h" #include "langhooks.h" #include "flags.h" #include "function.h" #include "diagnostic.h" #include "tree-pretty-print.h" #include "tree-dump.h" #include "gimple.h" #include "tree-flow.h" #include "tree-inline.h" #include "tree-pass.h" #include "convert.h" #include "params.h" #include "ipa-type-escape.h" #include "vec.h" #include "bitmap.h" #include "vecprim.h" #include "pointer-set.h" #include "alloc-pool.h" #include "tree-ssa-alias.h" /* Broad overview of how alias analysis on gimple works: Statements clobbering or using memory are linked through the virtual operand factored use-def chain. The virtual operand is unique per function, its symbol is accessible via gimple_vop (cfun). Virtual operands are used for efficiently walking memory statements in the gimple IL and are useful for things like value-numbering as a generation count for memory references. SSA_NAME pointers may have associated points-to information accessible via the SSA_NAME_PTR_INFO macro. Flow-insensitive points-to information is (re-)computed by the TODO_rebuild_alias pass manager todo. Points-to information is also used for more precise tracking of call-clobbered and call-used variables and related disambiguations. This file contains functions for disambiguating memory references, the so called alias-oracle and tools for walking of the gimple IL. The main alias-oracle entry-points are bool stmt_may_clobber_ref_p (gimple, tree) This function queries if a statement may invalidate (parts of) the memory designated by the reference tree argument. bool ref_maybe_used_by_stmt_p (gimple, tree) This function queries if a statement may need (parts of) the memory designated by the reference tree argument. There are variants of these functions that only handle the call part of a statement, call_may_clobber_ref_p and ref_maybe_used_by_call_p. Note that these do not disambiguate against a possible call lhs. bool refs_may_alias_p (tree, tree) This function tries to disambiguate two reference trees. bool ptr_deref_may_alias_global_p (tree) This function queries if dereferencing a pointer variable may alias global memory. More low-level disambiguators are available and documented in this file. Low-level disambiguators dealing with points-to information are in tree-ssa-structalias.c. */ /* Query statistics for the different low-level disambiguators. A high-level query may trigger multiple of them. */ static struct { unsigned HOST_WIDE_INT refs_may_alias_p_may_alias; unsigned HOST_WIDE_INT refs_may_alias_p_no_alias; unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_may_alias; unsigned HOST_WIDE_INT ref_maybe_used_by_call_p_no_alias; unsigned HOST_WIDE_INT call_may_clobber_ref_p_may_alias; unsigned HOST_WIDE_INT call_may_clobber_ref_p_no_alias; } alias_stats; void dump_alias_stats (FILE *s) { fprintf (s, "\nAlias oracle query stats:\n"); fprintf (s, " refs_may_alias_p: " HOST_WIDE_INT_PRINT_DEC" disambiguations, " HOST_WIDE_INT_PRINT_DEC" queries\n", alias_stats.refs_may_alias_p_no_alias, alias_stats.refs_may_alias_p_no_alias + alias_stats.refs_may_alias_p_may_alias); fprintf (s, " ref_maybe_used_by_call_p: " HOST_WIDE_INT_PRINT_DEC" disambiguations, " HOST_WIDE_INT_PRINT_DEC" queries\n", alias_stats.ref_maybe_used_by_call_p_no_alias, alias_stats.refs_may_alias_p_no_alias + alias_stats.ref_maybe_used_by_call_p_may_alias); fprintf (s, " call_may_clobber_ref_p: " HOST_WIDE_INT_PRINT_DEC" disambiguations, " HOST_WIDE_INT_PRINT_DEC" queries\n", alias_stats.call_may_clobber_ref_p_no_alias, alias_stats.call_may_clobber_ref_p_no_alias + alias_stats.call_may_clobber_ref_p_may_alias); } /* Return true, if dereferencing PTR may alias with a global variable. */ bool ptr_deref_may_alias_global_p (tree ptr) { struct ptr_info_def *pi; /* If we end up with a pointer constant here that may point to global memory. */ if (TREE_CODE (ptr) != SSA_NAME) return true; pi = SSA_NAME_PTR_INFO (ptr); /* If we do not have points-to information for this variable, we have to punt. */ if (!pi) return true; /* ??? This does not use TBAA to prune globals ptr may not access. */ return pt_solution_includes_global (&pi->pt); } /* Return true if dereferencing PTR may alias DECL. The caller is responsible for applying TBAA to see if PTR may access DECL at all. */ static bool ptr_deref_may_alias_decl_p (tree ptr, tree decl) { struct ptr_info_def *pi; gcc_assert ((TREE_CODE (ptr) == SSA_NAME || TREE_CODE (ptr) == ADDR_EXPR || TREE_CODE (ptr) == INTEGER_CST) && (TREE_CODE (decl) == VAR_DECL || TREE_CODE (decl) == PARM_DECL || TREE_CODE (decl) == RESULT_DECL)); /* Non-aliased variables can not be pointed to. */ if (!may_be_aliased (decl)) return false; /* ADDR_EXPR pointers either just offset another pointer or directly specify the pointed-to set. */ if (TREE_CODE (ptr) == ADDR_EXPR) { tree base = get_base_address (TREE_OPERAND (ptr, 0)); if (base && INDIRECT_REF_P (base)) ptr = TREE_OPERAND (base, 0); else if (base && SSA_VAR_P (base)) return base == decl; else if (base && CONSTANT_CLASS_P (base)) return false; else return true; } /* We can end up with dereferencing constant pointers. Just bail out in this case. */ if (TREE_CODE (ptr) == INTEGER_CST) return true; /* If we do not have useful points-to information for this pointer we cannot disambiguate anything else. */ pi = SSA_NAME_PTR_INFO (ptr); if (!pi) return true; /* If the decl can be used as a restrict tag and we have a restrict pointer and that pointers points-to set doesn't contain this decl then they can't alias. */ if (DECL_RESTRICTED_P (decl) && TYPE_RESTRICT (TREE_TYPE (ptr)) && pi->pt.vars_contains_restrict) return bitmap_bit_p (pi->pt.vars, DECL_PT_UID (decl)); return pt_solution_includes (&pi->pt, decl); } /* Return true if dereferenced PTR1 and PTR2 may alias. The caller is responsible for applying TBAA to see if accesses through PTR1 and PTR2 may conflict at all. */ static bool ptr_derefs_may_alias_p (tree ptr1, tree ptr2) { struct ptr_info_def *pi1, *pi2; gcc_assert ((TREE_CODE (ptr1) == SSA_NAME || TREE_CODE (ptr1) == ADDR_EXPR || TREE_CODE (ptr1) == INTEGER_CST) && (TREE_CODE (ptr2) == SSA_NAME || TREE_CODE (ptr2) == ADDR_EXPR || TREE_CODE (ptr2) == INTEGER_CST)); /* ADDR_EXPR pointers either just offset another pointer or directly specify the pointed-to set. */ if (TREE_CODE (ptr1) == ADDR_EXPR) { tree base = get_base_address (TREE_OPERAND (ptr1, 0)); if (base && INDIRECT_REF_P (base)) ptr1 = TREE_OPERAND (base, 0); else if (base && SSA_VAR_P (base)) return ptr_deref_may_alias_decl_p (ptr2, base); else return true; } if (TREE_CODE (ptr2) == ADDR_EXPR) { tree base = get_base_address (TREE_OPERAND (ptr2, 0)); if (base && INDIRECT_REF_P (base)) ptr2 = TREE_OPERAND (base, 0); else if (base && SSA_VAR_P (base)) return ptr_deref_may_alias_decl_p (ptr1, base); else return true; } /* We can end up with dereferencing constant pointers. Just bail out in this case. */ if (TREE_CODE (ptr1) == INTEGER_CST || TREE_CODE (ptr2) == INTEGER_CST) return true; /* We may end up with two empty points-to solutions for two same pointers. In this case we still want to say both pointers alias, so shortcut that here. */ if (ptr1 == ptr2) return true; /* If we do not have useful points-to information for either pointer we cannot disambiguate anything else. */ pi1 = SSA_NAME_PTR_INFO (ptr1); pi2 = SSA_NAME_PTR_INFO (ptr2); if (!pi1 || !pi2) return true; /* If both pointers are restrict-qualified try to disambiguate with restrict information. */ if (TYPE_RESTRICT (TREE_TYPE (ptr1)) && TYPE_RESTRICT (TREE_TYPE (ptr2)) && !pt_solutions_same_restrict_base (&pi1->pt, &pi2->pt)) return false; /* ??? This does not use TBAA to prune decls from the intersection that not both pointers may access. */ return pt_solutions_intersect (&pi1->pt, &pi2->pt); } /* Return true if dereferencing PTR may alias *REF. The caller is responsible for applying TBAA to see if PTR may access *REF at all. */ static bool ptr_deref_may_alias_ref_p_1 (tree ptr, ao_ref *ref) { tree base = ao_ref_base (ref); if (INDIRECT_REF_P (base)) return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0)); else if (SSA_VAR_P (base)) return ptr_deref_may_alias_decl_p (ptr, base); return true; } /* Dump alias information on FILE. */ void dump_alias_info (FILE *file) { size_t i; const char *funcname = lang_hooks.decl_printable_name (current_function_decl, 2); referenced_var_iterator rvi; tree var; fprintf (file, "\n\nAlias information for %s\n\n", funcname); fprintf (file, "Aliased symbols\n\n"); FOR_EACH_REFERENCED_VAR (var, rvi) { if (may_be_aliased (var)) dump_variable (file, var); } fprintf (file, "\nCall clobber information\n"); fprintf (file, "\nESCAPED"); dump_points_to_solution (file, &cfun->gimple_df->escaped); fprintf (file, "\n\nFlow-insensitive points-to information\n\n"); for (i = 1; i < num_ssa_names; i++) { tree ptr = ssa_name (i); struct ptr_info_def *pi; if (ptr == NULL_TREE || SSA_NAME_IN_FREE_LIST (ptr)) continue; pi = SSA_NAME_PTR_INFO (ptr); if (pi) dump_points_to_info_for (file, ptr); } fprintf (file, "\n"); } /* Dump alias information on stderr. */ DEBUG_FUNCTION void debug_alias_info (void) { dump_alias_info (stderr); } /* Return the alias information associated with pointer T. It creates a new instance if none existed. */ struct ptr_info_def * get_ptr_info (tree t) { struct ptr_info_def *pi; gcc_assert (POINTER_TYPE_P (TREE_TYPE (t))); pi = SSA_NAME_PTR_INFO (t); if (pi == NULL) { pi = GGC_CNEW (struct ptr_info_def); pt_solution_reset (&pi->pt); SSA_NAME_PTR_INFO (t) = pi; } return pi; } /* Dump the points-to set *PT into FILE. */ void dump_points_to_solution (FILE *file, struct pt_solution *pt) { if (pt->anything) fprintf (file, ", points-to anything"); if (pt->nonlocal) fprintf (file, ", points-to non-local"); if (pt->escaped) fprintf (file, ", points-to escaped"); if (pt->ipa_escaped) fprintf (file, ", points-to unit escaped"); if (pt->null) fprintf (file, ", points-to NULL"); if (pt->vars) { fprintf (file, ", points-to vars: "); dump_decl_set (file, pt->vars); if (pt->vars_contains_global) fprintf (file, " (includes global vars)"); if (pt->vars_contains_restrict) fprintf (file, " (includes restrict tags)"); } } /* Dump points-to information for SSA_NAME PTR into FILE. */ void dump_points_to_info_for (FILE *file, tree ptr) { struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr); print_generic_expr (file, ptr, dump_flags); if (pi) dump_points_to_solution (file, &pi->pt); else fprintf (file, ", points-to anything"); fprintf (file, "\n"); } /* Dump points-to information for VAR into stderr. */ DEBUG_FUNCTION void debug_points_to_info_for (tree var) { dump_points_to_info_for (stderr, var); } /* Initializes the alias-oracle reference representation *R from REF. */ void ao_ref_init (ao_ref *r, tree ref) { r->ref = ref; r->base = NULL_TREE; r->offset = 0; r->size = -1; r->max_size = -1; r->ref_alias_set = -1; r->base_alias_set = -1; } /* Returns the base object of the memory reference *REF. */ tree ao_ref_base (ao_ref *ref) { if (ref->base) return ref->base; ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size, &ref->max_size); return ref->base; } /* Returns the base object alias set of the memory reference *REF. */ static alias_set_type ATTRIBUTE_UNUSED ao_ref_base_alias_set (ao_ref *ref) { if (ref->base_alias_set != -1) return ref->base_alias_set; ref->base_alias_set = get_alias_set (ao_ref_base (ref)); return ref->base_alias_set; } /* Returns the reference alias set of the memory reference *REF. */ alias_set_type ao_ref_alias_set (ao_ref *ref) { if (ref->ref_alias_set != -1) return ref->ref_alias_set; ref->ref_alias_set = get_alias_set (ref->ref); return ref->ref_alias_set; } /* Init an alias-oracle reference representation from a gimple pointer PTR and a gimple size SIZE in bytes. If SIZE is NULL_TREE the the size is assumed to be unknown. The access is assumed to be only to or after of the pointer target, not before it. */ void ao_ref_init_from_ptr_and_size (ao_ref *ref, tree ptr, tree size) { HOST_WIDE_INT t1, t2; ref->ref = NULL_TREE; if (TREE_CODE (ptr) == ADDR_EXPR) ref->base = get_ref_base_and_extent (TREE_OPERAND (ptr, 0), &ref->offset, &t1, &t2); else { ref->base = build1 (INDIRECT_REF, char_type_node, ptr); ref->offset = 0; } if (size && host_integerp (size, 0) && TREE_INT_CST_LOW (size) * 8 / 8 == TREE_INT_CST_LOW (size)) ref->max_size = ref->size = TREE_INT_CST_LOW (size) * 8; else ref->max_size = ref->size = -1; ref->ref_alias_set = 0; ref->base_alias_set = 0; } /* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the purpose of TBAA. Return 0 if they are distinct and -1 if we cannot decide. */ static inline int same_type_for_tbaa (tree type1, tree type2) { type1 = TYPE_MAIN_VARIANT (type1); type2 = TYPE_MAIN_VARIANT (type2); /* If we would have to do structural comparison bail out. */ if (TYPE_STRUCTURAL_EQUALITY_P (type1) || TYPE_STRUCTURAL_EQUALITY_P (type2)) return -1; /* Compare the canonical types. */ if (TYPE_CANONICAL (type1) == TYPE_CANONICAL (type2)) return 1; /* ??? Array types are not properly unified in all cases as we have spurious changes in the index types for example. Removing this causes all sorts of problems with the Fortran frontend. */ if (TREE_CODE (type1) == ARRAY_TYPE && TREE_CODE (type2) == ARRAY_TYPE) return -1; /* ??? In Ada, an lvalue of an unconstrained type can be used to access an object of one of its constrained subtypes, e.g. when a function with an unconstrained parameter passed by reference is called on an object and inlined. But, even in the case of a fixed size, type and subtypes are not equivalent enough as to share the same TYPE_CANONICAL, since this would mean that conversions between them are useless, whereas they are not (e.g. type and subtypes can have different modes). So, in the end, they are only guaranteed to have the same alias set. */ if (get_alias_set (type1) == get_alias_set (type2)) return -1; /* The types are known to be not equal. */ return 0; } /* Determine if the two component references REF1 and REF2 which are based on access types TYPE1 and TYPE2 and of which at least one is based on an indirect reference may alias. REF2 is the only one that can be a decl in which case REF2_IS_DECL is true. REF1_ALIAS_SET, BASE1_ALIAS_SET, REF2_ALIAS_SET and BASE2_ALIAS_SET are the respective alias sets. */ static bool aliasing_component_refs_p (tree ref1, tree type1, alias_set_type ref1_alias_set, alias_set_type base1_alias_set, HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1, tree ref2, tree type2, alias_set_type ref2_alias_set, alias_set_type base2_alias_set, HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2, bool ref2_is_decl) { /* If one reference is a component references through pointers try to find a common base and apply offset based disambiguation. This handles for example struct A { int i; int j; } *q; struct B { struct A a; int k; } *p; disambiguating q->i and p->a.j. */ tree *refp; int same_p; /* Now search for the type1 in the access path of ref2. This would be a common base for doing offset based disambiguation on. */ refp = &ref2; while (handled_component_p (*refp) && same_type_for_tbaa (TREE_TYPE (*refp), type1) == 0) refp = &TREE_OPERAND (*refp, 0); same_p = same_type_for_tbaa (TREE_TYPE (*refp), type1); /* If we couldn't compare types we have to bail out. */ if (same_p == -1) return true; else if (same_p == 1) { HOST_WIDE_INT offadj, sztmp, msztmp; get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp); offset2 -= offadj; return ranges_overlap_p (offset1, max_size1, offset2, max_size2); } /* If we didn't find a common base, try the other way around. */ refp = &ref1; while (handled_component_p (*refp) && same_type_for_tbaa (TREE_TYPE (*refp), type2) == 0) refp = &TREE_OPERAND (*refp, 0); same_p = same_type_for_tbaa (TREE_TYPE (*refp), type2); /* If we couldn't compare types we have to bail out. */ if (same_p == -1) return true; else if (same_p == 1) { HOST_WIDE_INT offadj, sztmp, msztmp; get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp); offset1 -= offadj; return ranges_overlap_p (offset1, max_size1, offset2, max_size2); } /* If we have two type access paths B1.path1 and B2.path2 they may only alias if either B1 is in B2.path2 or B2 is in B1.path1. But we can still have a path that goes B1.path1...B2.path2 with a part that we do not see. So we can only disambiguate now if there is no B2 in the tail of path1 and no B1 on the tail of path2. */ if (base1_alias_set == ref2_alias_set || alias_set_subset_of (base1_alias_set, ref2_alias_set)) return true; /* If this is ptr vs. decl then we know there is no ptr ... decl path. */ if (!ref2_is_decl) return (base2_alias_set == ref1_alias_set || alias_set_subset_of (base2_alias_set, ref1_alias_set)); return false; } /* Return true if two memory references based on the variables BASE1 and BASE2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. */ static bool decl_refs_may_alias_p (tree base1, HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1, tree base2, HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2) { gcc_assert (SSA_VAR_P (base1) && SSA_VAR_P (base2)); /* If both references are based on different variables, they cannot alias. */ if (base1 != base2) return false; /* If both references are based on the same variable, they cannot alias if the accesses do not overlap. */ return ranges_overlap_p (offset1, max_size1, offset2, max_size2); } /* Return true if an indirect reference based on *PTR1 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2 constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1 in which case they are computed on-demand. REF1 and REF2 if non-NULL are the complete memory reference trees. */ static bool indirect_ref_may_alias_decl_p (tree ref1, tree ptr1, HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1, alias_set_type ref1_alias_set, alias_set_type base1_alias_set, tree ref2, tree base2, HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2, alias_set_type ref2_alias_set, alias_set_type base2_alias_set) { /* If only one reference is based on a variable, they cannot alias if the pointer access is beyond the extent of the variable access. (the pointer base cannot validly point to an offset less than zero of the variable). They also cannot alias if the pointer may not point to the decl. */ if (max_size2 != -1 && !ranges_overlap_p (offset1, max_size1, 0, offset2 + max_size2)) return false; if (!ptr_deref_may_alias_decl_p (ptr1, base2)) return false; /* Disambiguations that rely on strict aliasing rules follow. */ if (!flag_strict_aliasing) return true; /* If the alias set for a pointer access is zero all bets are off. */ if (base1_alias_set == -1) base1_alias_set = get_deref_alias_set (ptr1); if (base1_alias_set == 0) return true; if (base2_alias_set == -1) base2_alias_set = get_alias_set (base2); /* If both references are through the same type, they do not alias if the accesses do not overlap. This does extra disambiguation for mixed/pointer accesses but requires strict aliasing. */ if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1)), TREE_TYPE (base2)) == 1) return ranges_overlap_p (offset1, max_size1, offset2, max_size2); /* The only way to access a variable is through a pointer dereference of the same alias set or a subset of it. */ if (base1_alias_set != base2_alias_set && !alias_set_subset_of (base1_alias_set, base2_alias_set)) return false; /* Do access-path based disambiguation. */ if (ref1 && ref2 && handled_component_p (ref1) && handled_component_p (ref2)) return aliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)), ref1_alias_set, base1_alias_set, offset1, max_size1, ref2, TREE_TYPE (base2), ref2_alias_set, base2_alias_set, offset2, max_size2, true); return true; } /* Return true if two indirect references based on *PTR1 and *PTR2 constrained to [OFFSET1, OFFSET1 + MAX_SIZE1) and [OFFSET2, OFFSET2 + MAX_SIZE2) may alias. *PTR1 and *PTR2 have the alias sets BASE1_ALIAS_SET and BASE2_ALIAS_SET which can be -1 in which case they are computed on-demand. REF1 and REF2 if non-NULL are the complete memory reference trees. */ static bool indirect_refs_may_alias_p (tree ref1, tree ptr1, HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1, alias_set_type ref1_alias_set, alias_set_type base1_alias_set, tree ref2, tree ptr2, HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2, alias_set_type ref2_alias_set, alias_set_type base2_alias_set) { /* If both bases are based on pointers they cannot alias if they may not point to the same memory object or if they point to the same object and the accesses do not overlap. */ if (operand_equal_p (ptr1, ptr2, 0)) return ranges_overlap_p (offset1, max_size1, offset2, max_size2); if (!ptr_derefs_may_alias_p (ptr1, ptr2)) return false; /* Disambiguations that rely on strict aliasing rules follow. */ if (!flag_strict_aliasing) return true; /* If the alias set for a pointer access is zero all bets are off. */ if (base1_alias_set == -1) base1_alias_set = get_deref_alias_set (ptr1); if (base1_alias_set == 0) return true; if (base2_alias_set == -1) base2_alias_set = get_deref_alias_set (ptr2); if (base2_alias_set == 0) return true; /* If both references are through the same type, they do not alias if the accesses do not overlap. This does extra disambiguation for mixed/pointer accesses but requires strict aliasing. */ if (same_type_for_tbaa (TREE_TYPE (TREE_TYPE (ptr1)), TREE_TYPE (TREE_TYPE (ptr2))) == 1) return ranges_overlap_p (offset1, max_size1, offset2, max_size2); /* Do type-based disambiguation. */ if (base1_alias_set != base2_alias_set && !alias_sets_conflict_p (base1_alias_set, base2_alias_set)) return false; /* Do access-path based disambiguation. */ if (ref1 && ref2 && handled_component_p (ref1) && handled_component_p (ref2)) return aliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)), ref1_alias_set, base1_alias_set, offset1, max_size1, ref2, TREE_TYPE (TREE_TYPE (ptr2)), ref2_alias_set, base2_alias_set, offset2, max_size2, false); return true; } /* Return true, if the two memory references REF1 and REF2 may alias. */ bool refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p) { tree base1, base2; HOST_WIDE_INT offset1 = 0, offset2 = 0; HOST_WIDE_INT max_size1 = -1, max_size2 = -1; bool var1_p, var2_p, ind1_p, ind2_p; alias_set_type set; gcc_assert ((!ref1->ref || SSA_VAR_P (ref1->ref) || handled_component_p (ref1->ref) || INDIRECT_REF_P (ref1->ref) || TREE_CODE (ref1->ref) == TARGET_MEM_REF || TREE_CODE (ref1->ref) == CONST_DECL) && (!ref2->ref || SSA_VAR_P (ref2->ref) || handled_component_p (ref2->ref) || INDIRECT_REF_P (ref2->ref) || TREE_CODE (ref2->ref) == TARGET_MEM_REF || TREE_CODE (ref2->ref) == CONST_DECL)); /* Decompose the references into their base objects and the access. */ base1 = ao_ref_base (ref1); offset1 = ref1->offset; max_size1 = ref1->max_size; base2 = ao_ref_base (ref2); offset2 = ref2->offset; max_size2 = ref2->max_size; /* We can end up with registers or constants as bases for example from *D.1663_44 = VIEW_CONVERT_EXPR(__tmp$B0F64_59); which is seen as a struct copy. */ if (TREE_CODE (base1) == SSA_NAME || TREE_CODE (base2) == SSA_NAME || TREE_CODE (base1) == CONST_DECL || TREE_CODE (base2) == CONST_DECL || is_gimple_min_invariant (base1) || is_gimple_min_invariant (base2)) return false; /* We can end up refering to code via function decls. As we likely do not properly track code aliases conservatively bail out. */ if (TREE_CODE (base1) == FUNCTION_DECL || TREE_CODE (base2) == FUNCTION_DECL) return true; /* Defer to simple offset based disambiguation if we have references based on two decls. Do this before defering to TBAA to handle must-alias cases in conformance with the GCC extension of allowing type-punning through unions. */ var1_p = SSA_VAR_P (base1); var2_p = SSA_VAR_P (base2); if (var1_p && var2_p) return decl_refs_may_alias_p (base1, offset1, max_size1, base2, offset2, max_size2); ind1_p = INDIRECT_REF_P (base1); ind2_p = INDIRECT_REF_P (base2); /* Canonicalize the pointer-vs-decl case. */ if (ind1_p && var2_p) { HOST_WIDE_INT tmp1; tree tmp2; ao_ref *tmp3; tmp1 = offset1; offset1 = offset2; offset2 = tmp1; tmp1 = max_size1; max_size1 = max_size2; max_size2 = tmp1; tmp2 = base1; base1 = base2; base2 = tmp2; tmp3 = ref1; ref1 = ref2; ref2 = tmp3; var1_p = true; ind1_p = false; var2_p = false; ind2_p = true; } /* If we are about to disambiguate pointer-vs-decl try harder to see must-aliases and give leeway to some invalid cases. This covers a pretty minimal set of cases only and does not when called from the RTL oracle. It handles cases like int i = 1; return *(float *)&i; and also fixes gfortran.dg/lto/pr40725. */ if (var1_p && ind2_p && cfun && gimple_in_ssa_p (cfun) && TREE_CODE (TREE_OPERAND (base2, 0)) == SSA_NAME) { gimple def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (base2, 0)); while (is_gimple_assign (def_stmt) && (gimple_assign_rhs_code (def_stmt) == SSA_NAME || CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt)))) { tree rhs = gimple_assign_rhs1 (def_stmt); HOST_WIDE_INT offset, size, max_size; /* Look through SSA name copies and pointer conversions. */ if (TREE_CODE (rhs) == SSA_NAME && POINTER_TYPE_P (TREE_TYPE (rhs))) { def_stmt = SSA_NAME_DEF_STMT (rhs); continue; } if (TREE_CODE (rhs) != ADDR_EXPR) break; /* If the pointer is defined as an address based on a decl use plain offset disambiguation and ignore TBAA. */ rhs = TREE_OPERAND (rhs, 0); rhs = get_ref_base_and_extent (rhs, &offset, &size, &max_size); if (SSA_VAR_P (rhs)) { base2 = rhs; offset2 += offset; if (size != max_size || max_size == -1) max_size2 = -1; return decl_refs_may_alias_p (base1, offset1, max_size1, base2, offset2, max_size2); } /* Do not continue looking through &p->x to limit time complexity. */ break; } } /* First defer to TBAA if possible. */ if (tbaa_p && flag_strict_aliasing && !alias_sets_conflict_p (ao_ref_alias_set (ref1), ao_ref_alias_set (ref2))) return false; /* If one reference is a TARGET_MEM_REF weird things are allowed. Still TBAA disambiguation based on the access type is possible, so bail out only after that check. */ if ((ref1->ref && TREE_CODE (ref1->ref) == TARGET_MEM_REF) || (ref2->ref && TREE_CODE (ref2->ref) == TARGET_MEM_REF)) return true; /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */ set = tbaa_p ? -1 : 0; if (var1_p && ind2_p) return indirect_ref_may_alias_decl_p (ref2->ref, TREE_OPERAND (base2, 0), offset2, max_size2, ao_ref_alias_set (ref2), set, ref1->ref, base1, offset1, max_size1, ao_ref_alias_set (ref1), set); else if (ind1_p && ind2_p) return indirect_refs_may_alias_p (ref1->ref, TREE_OPERAND (base1, 0), offset1, max_size1, ao_ref_alias_set (ref1), set, ref2->ref, TREE_OPERAND (base2, 0), offset2, max_size2, ao_ref_alias_set (ref2), set); gcc_unreachable (); } bool refs_may_alias_p (tree ref1, tree ref2) { ao_ref r1, r2; bool res; ao_ref_init (&r1, ref1); ao_ref_init (&r2, ref2); res = refs_may_alias_p_1 (&r1, &r2, true); if (res) ++alias_stats.refs_may_alias_p_may_alias; else ++alias_stats.refs_may_alias_p_no_alias; return res; } /* Returns true if there is a anti-dependence for the STORE that executes after the LOAD. */ bool refs_anti_dependent_p (tree load, tree store) { ao_ref r1, r2; ao_ref_init (&r1, load); ao_ref_init (&r2, store); return refs_may_alias_p_1 (&r1, &r2, false); } /* Returns true if there is a output dependence for the stores STORE1 and STORE2. */ bool refs_output_dependent_p (tree store1, tree store2) { ao_ref r1, r2; ao_ref_init (&r1, store1); ao_ref_init (&r2, store2); return refs_may_alias_p_1 (&r1, &r2, false); } /* If the call CALL may use the memory reference REF return true, otherwise return false. */ static bool ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref) { tree base, callee; unsigned i; int flags = gimple_call_flags (call); /* Const functions without a static chain do not implicitly use memory. */ if (!gimple_call_chain (call) && (flags & (ECF_CONST|ECF_NOVOPS))) goto process_args; base = ao_ref_base (ref); if (!base) return true; /* If the reference is based on a decl that is not aliased the call cannot possibly use it. */ if (DECL_P (base) && !may_be_aliased (base) /* But local statics can be used through recursion. */ && !is_global_var (base)) goto process_args; callee = gimple_call_fndecl (call); /* Handle those builtin functions explicitly that do not act as escape points. See tree-ssa-structalias.c:find_func_aliases for the list of builtins we might need to handle here. */ if (callee != NULL_TREE && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL) switch (DECL_FUNCTION_CODE (callee)) { /* All the following functions clobber memory pointed to by their first argument. */ case BUILT_IN_STRCPY: case BUILT_IN_STRNCPY: case BUILT_IN_MEMCPY: case BUILT_IN_MEMMOVE: case BUILT_IN_MEMPCPY: case BUILT_IN_STPCPY: case BUILT_IN_STPNCPY: case BUILT_IN_STRCAT: case BUILT_IN_STRNCAT: { ao_ref dref; tree size = NULL_TREE; if (gimple_call_num_args (call) == 3) size = gimple_call_arg (call, 2); ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 1), size); return refs_may_alias_p_1 (&dref, ref, false); } case BUILT_IN_BCOPY: { ao_ref dref; tree size = gimple_call_arg (call, 2); ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 0), size); return refs_may_alias_p_1 (&dref, ref, false); } /* The following builtins do not read from memory. */ case BUILT_IN_FREE: case BUILT_IN_MALLOC: case BUILT_IN_CALLOC: case BUILT_IN_MEMSET: case BUILT_IN_FREXP: case BUILT_IN_FREXPF: case BUILT_IN_FREXPL: case BUILT_IN_GAMMA_R: case BUILT_IN_GAMMAF_R: case BUILT_IN_GAMMAL_R: case BUILT_IN_LGAMMA_R: case BUILT_IN_LGAMMAF_R: case BUILT_IN_LGAMMAL_R: case BUILT_IN_MODF: case BUILT_IN_MODFF: case BUILT_IN_MODFL: case BUILT_IN_REMQUO: case BUILT_IN_REMQUOF: case BUILT_IN_REMQUOL: case BUILT_IN_SINCOS: case BUILT_IN_SINCOSF: case BUILT_IN_SINCOSL: return false; default: /* Fallthru to general call handling. */; } /* Check if base is a global static variable that is not read by the function. */ if (TREE_CODE (base) == VAR_DECL && TREE_STATIC (base)) { bitmap not_read; if (callee != NULL_TREE && (not_read = ipa_reference_get_not_read_global (cgraph_node (callee))) && bitmap_bit_p (not_read, DECL_UID (base))) goto process_args; } /* Check if the base variable is call-used. */ if (DECL_P (base)) { if (pt_solution_includes (gimple_call_use_set (call), base)) return true; } else if (INDIRECT_REF_P (base) && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) { struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0)); if (!pi) return true; if (pt_solutions_intersect (gimple_call_use_set (call), &pi->pt)) return true; } else return true; /* Inspect call arguments for passed-by-value aliases. */ process_args: for (i = 0; i < gimple_call_num_args (call); ++i) { tree op = gimple_call_arg (call, i); int flags = gimple_call_arg_flags (call, i); if (flags & EAF_UNUSED) continue; if (TREE_CODE (op) == WITH_SIZE_EXPR) op = TREE_OPERAND (op, 0); if (TREE_CODE (op) != SSA_NAME && !is_gimple_min_invariant (op)) { ao_ref r; ao_ref_init (&r, op); if (refs_may_alias_p_1 (&r, ref, true)) return true; } } return false; } static bool ref_maybe_used_by_call_p (gimple call, tree ref) { ao_ref r; bool res; ao_ref_init (&r, ref); res = ref_maybe_used_by_call_p_1 (call, &r); if (res) ++alias_stats.ref_maybe_used_by_call_p_may_alias; else ++alias_stats.ref_maybe_used_by_call_p_no_alias; return res; } /* If the statement STMT may use the memory reference REF return true, otherwise return false. */ bool ref_maybe_used_by_stmt_p (gimple stmt, tree ref) { if (is_gimple_assign (stmt)) { tree rhs; /* All memory assign statements are single. */ if (!gimple_assign_single_p (stmt)) return false; rhs = gimple_assign_rhs1 (stmt); if (is_gimple_reg (rhs) || is_gimple_min_invariant (rhs) || gimple_assign_rhs_code (stmt) == CONSTRUCTOR) return false; return refs_may_alias_p (rhs, ref); } else if (is_gimple_call (stmt)) return ref_maybe_used_by_call_p (stmt, ref); return true; } /* If the call in statement CALL may clobber the memory reference REF return true, otherwise return false. */ static bool call_may_clobber_ref_p_1 (gimple call, ao_ref *ref) { tree base; tree callee; /* If the call is pure or const it cannot clobber anything. */ if (gimple_call_flags (call) & (ECF_PURE|ECF_CONST|ECF_LOOPING_CONST_OR_PURE|ECF_NOVOPS)) return false; base = ao_ref_base (ref); if (!base) return true; if (TREE_CODE (base) == SSA_NAME || CONSTANT_CLASS_P (base)) return false; /* If the reference is based on a decl that is not aliased the call cannot possibly clobber it. */ if (DECL_P (base) && !may_be_aliased (base) /* But local non-readonly statics can be modified through recursion or the call may implement a threading barrier which we must treat as may-def. */ && (TREE_READONLY (base) || !is_global_var (base))) return false; callee = gimple_call_fndecl (call); /* Handle those builtin functions explicitly that do not act as escape points. See tree-ssa-structalias.c:find_func_aliases for the list of builtins we might need to handle here. */ if (callee != NULL_TREE && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL) switch (DECL_FUNCTION_CODE (callee)) { /* All the following functions clobber memory pointed to by their first argument. */ case BUILT_IN_STRCPY: case BUILT_IN_STRNCPY: case BUILT_IN_MEMCPY: case BUILT_IN_MEMMOVE: case BUILT_IN_MEMPCPY: case BUILT_IN_STPCPY: case BUILT_IN_STPNCPY: case BUILT_IN_STRCAT: case BUILT_IN_STRNCAT: case BUILT_IN_MEMSET: { ao_ref dref; tree size = NULL_TREE; if (gimple_call_num_args (call) == 3) size = gimple_call_arg (call, 2); ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 0), size); return refs_may_alias_p_1 (&dref, ref, false); } case BUILT_IN_BCOPY: { ao_ref dref; tree size = gimple_call_arg (call, 2); ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 1), size); return refs_may_alias_p_1 (&dref, ref, false); } /* Allocating memory does not have any side-effects apart from being the definition point for the pointer. */ case BUILT_IN_MALLOC: case BUILT_IN_CALLOC: /* Unix98 specifies that errno is set on allocation failure. Until we properly can track the errno location assume it is not a local decl but external or anonymous storage in a different translation unit. Also assume it is of type int as required by the standard. */ if (flag_errno_math && TREE_TYPE (base) == integer_type_node) { struct ptr_info_def *pi; if (DECL_P (base) && !TREE_STATIC (base)) return true; else if (INDIRECT_REF_P (base) && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME && (pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0)))) return pi->pt.anything || pi->pt.nonlocal; } return false; /* Freeing memory kills the pointed-to memory. More importantly the call has to serve as a barrier for moving loads and stores across it. */ case BUILT_IN_FREE: { tree ptr = gimple_call_arg (call, 0); return ptr_deref_may_alias_ref_p_1 (ptr, ref); } case BUILT_IN_GAMMA_R: case BUILT_IN_GAMMAF_R: case BUILT_IN_GAMMAL_R: case BUILT_IN_LGAMMA_R: case BUILT_IN_LGAMMAF_R: case BUILT_IN_LGAMMAL_R: { tree out = gimple_call_arg (call, 1); if (ptr_deref_may_alias_ref_p_1 (out, ref)) return true; if (flag_errno_math) break; return false; } case BUILT_IN_FREXP: case BUILT_IN_FREXPF: case BUILT_IN_FREXPL: case BUILT_IN_MODF: case BUILT_IN_MODFF: case BUILT_IN_MODFL: { tree out = gimple_call_arg (call, 1); return ptr_deref_may_alias_ref_p_1 (out, ref); } case BUILT_IN_REMQUO: case BUILT_IN_REMQUOF: case BUILT_IN_REMQUOL: { tree out = gimple_call_arg (call, 2); if (ptr_deref_may_alias_ref_p_1 (out, ref)) return true; if (flag_errno_math) break; return false; } case BUILT_IN_SINCOS: case BUILT_IN_SINCOSF: case BUILT_IN_SINCOSL: { tree sin = gimple_call_arg (call, 1); tree cos = gimple_call_arg (call, 2); return (ptr_deref_may_alias_ref_p_1 (sin, ref) || ptr_deref_may_alias_ref_p_1 (cos, ref)); } default: /* Fallthru to general call handling. */; } /* Check if base is a global static variable that is not written by the function. */ if (callee != NULL_TREE && TREE_CODE (base) == VAR_DECL && TREE_STATIC (base)) { bitmap not_written; if ((not_written = ipa_reference_get_not_written_global (cgraph_node (callee))) && bitmap_bit_p (not_written, DECL_UID (base))) return false; } /* Check if the base variable is call-clobbered. */ if (DECL_P (base)) return pt_solution_includes (gimple_call_clobber_set (call), base); else if (INDIRECT_REF_P (base) && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) { struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0)); if (!pi) return true; return pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt); } return true; } /* If the call in statement CALL may clobber the memory reference REF return true, otherwise return false. */ bool call_may_clobber_ref_p (gimple call, tree ref) { bool res; ao_ref r; ao_ref_init (&r, ref); res = call_may_clobber_ref_p_1 (call, &r); if (res) ++alias_stats.call_may_clobber_ref_p_may_alias; else ++alias_stats.call_may_clobber_ref_p_no_alias; return res; } /* If the statement STMT may clobber the memory reference REF return true, otherwise return false. */ bool stmt_may_clobber_ref_p_1 (gimple stmt, ao_ref *ref) { if (is_gimple_call (stmt)) { tree lhs = gimple_call_lhs (stmt); if (lhs && !is_gimple_reg (lhs)) { ao_ref r; ao_ref_init (&r, lhs); if (refs_may_alias_p_1 (ref, &r, true)) return true; } return call_may_clobber_ref_p_1 (stmt, ref); } else if (is_gimple_assign (stmt)) { ao_ref r; ao_ref_init (&r, gimple_assign_lhs (stmt)); return refs_may_alias_p_1 (ref, &r, true); } else if (gimple_code (stmt) == GIMPLE_ASM) return true; return false; } bool stmt_may_clobber_ref_p (gimple stmt, tree ref) { ao_ref r; ao_ref_init (&r, ref); return stmt_may_clobber_ref_p_1 (stmt, &r); } /* Walk the virtual use-def chain of VUSE until hitting the virtual operand TARGET or a statement clobbering the memory reference REF in which case false is returned. The walk starts with VUSE, one argument of PHI. */ static bool maybe_skip_until (gimple phi, tree target, ao_ref *ref, tree vuse, bitmap *visited) { if (!*visited) *visited = BITMAP_ALLOC (NULL); bitmap_set_bit (*visited, SSA_NAME_VERSION (PHI_RESULT (phi))); /* Walk until we hit the target. */ while (vuse != target) { gimple def_stmt = SSA_NAME_DEF_STMT (vuse); /* Recurse for PHI nodes. */ if (gimple_code (def_stmt) == GIMPLE_PHI) { /* An already visited PHI node ends the walk successfully. */ if (bitmap_bit_p (*visited, SSA_NAME_VERSION (PHI_RESULT (def_stmt)))) return true; vuse = get_continuation_for_phi (def_stmt, ref, visited); if (!vuse) return false; continue; } /* A clobbering statement or the end of the IL ends it failing. */ else if (gimple_nop_p (def_stmt) || stmt_may_clobber_ref_p_1 (def_stmt, ref)) return false; vuse = gimple_vuse (def_stmt); } return true; } /* Starting from a PHI node for the virtual operand of the memory reference REF find a continuation virtual operand that allows to continue walking statements dominating PHI skipping only statements that cannot possibly clobber REF. Returns NULL_TREE if no suitable virtual operand can be found. */ tree get_continuation_for_phi (gimple phi, ao_ref *ref, bitmap *visited) { unsigned nargs = gimple_phi_num_args (phi); /* Through a single-argument PHI we can simply look through. */ if (nargs == 1) return PHI_ARG_DEF (phi, 0); /* For two arguments try to skip non-aliasing code until we hit the phi argument definition that dominates the other one. */ if (nargs == 2) { tree arg0 = PHI_ARG_DEF (phi, 0); tree arg1 = PHI_ARG_DEF (phi, 1); gimple def0 = SSA_NAME_DEF_STMT (arg0); gimple def1 = SSA_NAME_DEF_STMT (arg1); tree common_vuse; if (arg0 == arg1) return arg0; else if (gimple_nop_p (def0) || (!gimple_nop_p (def1) && dominated_by_p (CDI_DOMINATORS, gimple_bb (def1), gimple_bb (def0)))) { if (maybe_skip_until (phi, arg0, ref, arg1, visited)) return arg0; } else if (gimple_nop_p (def1) || dominated_by_p (CDI_DOMINATORS, gimple_bb (def0), gimple_bb (def1))) { if (maybe_skip_until (phi, arg1, ref, arg0, visited)) return arg1; } /* Special case of a diamond: MEM_1 = ... goto (cond) ? L1 : L2 L1: store1 = ... #MEM_2 = vuse(MEM_1) goto L3 L2: store2 = ... #MEM_3 = vuse(MEM_1) L3: MEM_4 = PHI We were called with the PHI at L3, MEM_2 and MEM_3 don't dominate each other, but still we can easily skip this PHI node if we recognize that the vuse MEM operand is the same for both, and that we can skip both statements (they don't clobber us). This is still linear. Don't use maybe_skip_until, that might potentially be slow. */ else if ((common_vuse = gimple_vuse (def0)) && common_vuse == gimple_vuse (def1)) { if (!stmt_may_clobber_ref_p_1 (def0, ref) && !stmt_may_clobber_ref_p_1 (def1, ref)) return common_vuse; } } return NULL_TREE; } /* Based on the memory reference REF and its virtual use VUSE call WALKER for each virtual use that is equivalent to VUSE, including VUSE itself. That is, for each virtual use for which its defining statement does not clobber REF. WALKER is called with REF, the current virtual use and DATA. If WALKER returns non-NULL the walk stops and its result is returned. At the end of a non-successful walk NULL is returned. TRANSLATE if non-NULL is called with a pointer to REF, the virtual use which definition is a statement that may clobber REF and DATA. If TRANSLATE returns (void *)-1 the walk stops and NULL is returned. If TRANSLATE returns non-NULL the walk stops and its result is returned. If TRANSLATE returns NULL the walk continues and TRANSLATE is supposed to adjust REF and *DATA to make that valid. TODO: Cache the vector of equivalent vuses per ref, vuse pair. */ void * walk_non_aliased_vuses (ao_ref *ref, tree vuse, void *(*walker)(ao_ref *, tree, void *), void *(*translate)(ao_ref *, tree, void *), void *data) { bitmap visited = NULL; void *res; timevar_push (TV_ALIAS_STMT_WALK); do { gimple def_stmt; /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */ res = (*walker) (ref, vuse, data); if (res) break; def_stmt = SSA_NAME_DEF_STMT (vuse); if (gimple_nop_p (def_stmt)) break; else if (gimple_code (def_stmt) == GIMPLE_PHI) vuse = get_continuation_for_phi (def_stmt, ref, &visited); else { if (stmt_may_clobber_ref_p_1 (def_stmt, ref)) { if (!translate) break; res = (*translate) (ref, vuse, data); /* Failed lookup and translation. */ if (res == (void *)-1) { res = NULL; break; } /* Lookup succeeded. */ else if (res != NULL) break; /* Translation succeeded, continue walking. */ } vuse = gimple_vuse (def_stmt); } } while (vuse); if (visited) BITMAP_FREE (visited); timevar_pop (TV_ALIAS_STMT_WALK); return res; } /* Based on the memory reference REF call WALKER for each vdef which defining statement may clobber REF, starting with VDEF. If REF is NULL_TREE, each defining statement is visited. WALKER is called with REF, the current vdef and DATA. If WALKER returns true the walk is stopped, otherwise it continues. At PHI nodes walk_aliased_vdefs forks into one walk for reach PHI argument (but only one walk continues on merge points), the return value is true if any of the walks was successful. The function returns the number of statements walked. */ static unsigned int walk_aliased_vdefs_1 (ao_ref *ref, tree vdef, bool (*walker)(ao_ref *, tree, void *), void *data, bitmap *visited, unsigned int cnt) { do { gimple def_stmt = SSA_NAME_DEF_STMT (vdef); if (*visited && !bitmap_set_bit (*visited, SSA_NAME_VERSION (vdef))) return cnt; if (gimple_nop_p (def_stmt)) return cnt; else if (gimple_code (def_stmt) == GIMPLE_PHI) { unsigned i; if (!*visited) *visited = BITMAP_ALLOC (NULL); for (i = 0; i < gimple_phi_num_args (def_stmt); ++i) cnt += walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i), walker, data, visited, 0); return cnt; } /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */ cnt++; if ((!ref || stmt_may_clobber_ref_p_1 (def_stmt, ref)) && (*walker) (ref, vdef, data)) return cnt; vdef = gimple_vuse (def_stmt); } while (1); } unsigned int walk_aliased_vdefs (ao_ref *ref, tree vdef, bool (*walker)(ao_ref *, tree, void *), void *data, bitmap *visited) { bitmap local_visited = NULL; unsigned int ret; timevar_push (TV_ALIAS_STMT_WALK); ret = walk_aliased_vdefs_1 (ref, vdef, walker, data, visited ? visited : &local_visited, 0); if (local_visited) BITMAP_FREE (local_visited); timevar_pop (TV_ALIAS_STMT_WALK); return ret; }