/* Alias analysis for trees. Copyright (C) 2004-2017 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 "backend.h" #include "target.h" #include "rtl.h" #include "tree.h" #include "gimple.h" #include "timevar.h" /* for TV_ALIAS_STMT_WALK */ #include "ssa.h" #include "cgraph.h" #include "tree-pretty-print.h" #include "alias.h" #include "fold-const.h" #include "langhooks.h" #include "dumpfile.h" #include "tree-eh.h" #include "tree-dfa.h" #include "ipa-reference.h" #include "varasm.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); dump_alias_stats_in_alias_c (s); } /* 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; /* Conversions are irrelevant for points-to information and data-dependence analysis can feed us those. */ STRIP_NOPS (ptr); /* Anything we do not explicilty handle aliases. */ if ((TREE_CODE (ptr) != SSA_NAME && TREE_CODE (ptr) != ADDR_EXPR && TREE_CODE (ptr) != POINTER_PLUS_EXPR) || !POINTER_TYPE_P (TREE_TYPE (ptr)) || (!VAR_P (decl) && TREE_CODE (decl) != PARM_DECL && TREE_CODE (decl) != RESULT_DECL)) return true; /* Disregard pointer offsetting. */ if (TREE_CODE (ptr) == POINTER_PLUS_EXPR) { do { ptr = TREE_OPERAND (ptr, 0); } while (TREE_CODE (ptr) == POINTER_PLUS_EXPR); return ptr_deref_may_alias_decl_p (ptr, decl); } /* 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 && (TREE_CODE (base) == MEM_REF || TREE_CODE (base) == TARGET_MEM_REF)) ptr = TREE_OPERAND (base, 0); else if (base && DECL_P (base)) return compare_base_decls (base, decl) != 0; else if (base && CONSTANT_CLASS_P (base)) return false; else return true; } /* Non-aliased variables can not be pointed to. */ if (!may_be_aliased (decl)) return false; /* 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; 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. */ bool ptr_derefs_may_alias_p (tree ptr1, tree ptr2) { struct ptr_info_def *pi1, *pi2; /* Conversions are irrelevant for points-to information and data-dependence analysis can feed us those. */ STRIP_NOPS (ptr1); STRIP_NOPS (ptr2); /* Disregard pointer offsetting. */ if (TREE_CODE (ptr1) == POINTER_PLUS_EXPR) { do { ptr1 = TREE_OPERAND (ptr1, 0); } while (TREE_CODE (ptr1) == POINTER_PLUS_EXPR); return ptr_derefs_may_alias_p (ptr1, ptr2); } if (TREE_CODE (ptr2) == POINTER_PLUS_EXPR) { do { ptr2 = TREE_OPERAND (ptr2, 0); } while (TREE_CODE (ptr2) == POINTER_PLUS_EXPR); return ptr_derefs_may_alias_p (ptr1, ptr2); } /* 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 && (TREE_CODE (base) == MEM_REF || TREE_CODE (base) == TARGET_MEM_REF)) return ptr_derefs_may_alias_p (TREE_OPERAND (base, 0), ptr2); else if (base && DECL_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 && (TREE_CODE (base) == MEM_REF || TREE_CODE (base) == TARGET_MEM_REF)) return ptr_derefs_may_alias_p (ptr1, TREE_OPERAND (base, 0)); else if (base && DECL_P (base)) return ptr_deref_may_alias_decl_p (ptr1, base); else return true; } /* From here we require SSA name pointers. Anything else aliases. */ if (TREE_CODE (ptr1) != SSA_NAME || TREE_CODE (ptr2) != SSA_NAME || !POINTER_TYPE_P (TREE_TYPE (ptr1)) || !POINTER_TYPE_P (TREE_TYPE (ptr2))) 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; /* ??? 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 (TREE_CODE (base) == MEM_REF || TREE_CODE (base) == TARGET_MEM_REF) return ptr_derefs_may_alias_p (ptr, TREE_OPERAND (base, 0)); else if (DECL_P (base)) return ptr_deref_may_alias_decl_p (ptr, base); return true; } /* Returns true if PTR1 and PTR2 compare unequal because of points-to. */ bool ptrs_compare_unequal (tree ptr1, tree ptr2) { /* First resolve the pointers down to a SSA name pointer base or a VAR_DECL, PARM_DECL or RESULT_DECL. This explicitely does not yet try to handle LABEL_DECLs, FUNCTION_DECLs, CONST_DECLs or STRING_CSTs which needs points-to adjustments to track them in the points-to sets. */ tree obj1 = NULL_TREE; tree obj2 = NULL_TREE; if (TREE_CODE (ptr1) == ADDR_EXPR) { tree tem = get_base_address (TREE_OPERAND (ptr1, 0)); if (! tem) return false; if (VAR_P (tem) || TREE_CODE (tem) == PARM_DECL || TREE_CODE (tem) == RESULT_DECL) obj1 = tem; else if (TREE_CODE (tem) == MEM_REF) ptr1 = TREE_OPERAND (tem, 0); } if (TREE_CODE (ptr2) == ADDR_EXPR) { tree tem = get_base_address (TREE_OPERAND (ptr2, 0)); if (! tem) return false; if (VAR_P (tem) || TREE_CODE (tem) == PARM_DECL || TREE_CODE (tem) == RESULT_DECL) obj2 = tem; else if (TREE_CODE (tem) == MEM_REF) ptr2 = TREE_OPERAND (tem, 0); } /* Canonicalize ptr vs. object. */ if (TREE_CODE (ptr1) == SSA_NAME && obj2) { std::swap (ptr1, ptr2); std::swap (obj1, obj2); } if (obj1 && obj2) /* Other code handles this correctly, no need to duplicate it here. */; else if (obj1 && TREE_CODE (ptr2) == SSA_NAME) { struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr2); /* We may not use restrict to optimize pointer comparisons. See PR71062. So we have to assume that restrict-pointed-to may be in fact obj1. */ if (!pi || pi->pt.vars_contains_restrict || pi->pt.vars_contains_interposable) return false; if (VAR_P (obj1) && (TREE_STATIC (obj1) || DECL_EXTERNAL (obj1))) { varpool_node *node = varpool_node::get (obj1); /* If obj1 may bind to NULL give up (see below). */ if (! node || ! node->nonzero_address () || ! decl_binds_to_current_def_p (obj1)) return false; } return !pt_solution_includes (&pi->pt, obj1); } /* ??? We'd like to handle ptr1 != NULL and ptr1 != ptr2 but those require pt.null to be conservatively correct. */ return false; } /* Returns whether reference REF to BASE may refer to global memory. */ static bool ref_may_alias_global_p_1 (tree base) { if (DECL_P (base)) return is_global_var (base); else if (TREE_CODE (base) == MEM_REF || TREE_CODE (base) == TARGET_MEM_REF) return ptr_deref_may_alias_global_p (TREE_OPERAND (base, 0)); return true; } bool ref_may_alias_global_p (ao_ref *ref) { tree base = ao_ref_base (ref); return ref_may_alias_global_p_1 (base); } bool ref_may_alias_global_p (tree ref) { tree base = get_base_address (ref); return ref_may_alias_global_p_1 (base); } /* Return true whether STMT may clobber global memory. */ bool stmt_may_clobber_global_p (gimple *stmt) { tree lhs; if (!gimple_vdef (stmt)) return false; /* ??? We can ask the oracle whether an artificial pointer dereference with a pointer with points-to information covering all global memory (what about non-address taken memory?) maybe clobbered by this call. As there is at the moment no convenient way of doing that without generating garbage do some manual checking instead. ??? We could make a NULL ao_ref argument to the various predicates special, meaning any global memory. */ switch (gimple_code (stmt)) { case GIMPLE_ASSIGN: lhs = gimple_assign_lhs (stmt); return (TREE_CODE (lhs) != SSA_NAME && ref_may_alias_global_p (lhs)); case GIMPLE_CALL: return true; default: return true; } } /* Dump alias information on FILE. */ void dump_alias_info (FILE *file) { unsigned i; tree ptr; const char *funcname = lang_hooks.decl_printable_name (current_function_decl, 2); tree var; fprintf (file, "\n\nAlias information for %s\n\n", funcname); fprintf (file, "Aliased symbols\n\n"); FOR_EACH_LOCAL_DECL (cfun, i, var) { 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_EACH_SSA_NAME (i, ptr, cfun) { struct ptr_info_def *pi; if (!POINTER_TYPE_P (TREE_TYPE (ptr)) || 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); } /* 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_nonlocal || pt->vars_contains_escaped || pt->vars_contains_escaped_heap || pt->vars_contains_restrict) { const char *comma = ""; fprintf (file, " ("); if (pt->vars_contains_nonlocal) { fprintf (file, "nonlocal"); comma = ", "; } if (pt->vars_contains_escaped) { fprintf (file, "%sescaped", comma); comma = ", "; } if (pt->vars_contains_escaped_heap) { fprintf (file, "%sescaped heap", comma); comma = ", "; } if (pt->vars_contains_restrict) { fprintf (file, "%srestrict", comma); comma = ", "; } if (pt->vars_contains_interposable) fprintf (file, "%sinterposable", comma); fprintf (file, ")"); } } } /* Unified dump function for pt_solution. */ DEBUG_FUNCTION void debug (pt_solution &ref) { dump_points_to_solution (stderr, &ref); } DEBUG_FUNCTION void debug (pt_solution *ptr) { if (ptr) debug (*ptr); else fprintf (stderr, "\n"); } /* 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; r->volatile_p = ref ? TREE_THIS_VOLATILE (ref) : false; } /* Returns the base object of the memory reference *REF. */ tree ao_ref_base (ao_ref *ref) { bool reverse; if (ref->base) return ref->base; ref->base = get_ref_base_and_extent (ref->ref, &ref->offset, &ref->size, &ref->max_size, &reverse); return ref->base; } /* Returns the base object alias set of the memory reference *REF. */ alias_set_type ao_ref_base_alias_set (ao_ref *ref) { tree base_ref; if (ref->base_alias_set != -1) return ref->base_alias_set; if (!ref->ref) return 0; base_ref = ref->ref; while (handled_component_p (base_ref)) base_ref = TREE_OPERAND (base_ref, 0); ref->base_alias_set = get_alias_set (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 then 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 t, size_hwi, extra_offset = 0; ref->ref = NULL_TREE; if (TREE_CODE (ptr) == SSA_NAME) { gimple *stmt = SSA_NAME_DEF_STMT (ptr); if (gimple_assign_single_p (stmt) && gimple_assign_rhs_code (stmt) == ADDR_EXPR) ptr = gimple_assign_rhs1 (stmt); else if (is_gimple_assign (stmt) && gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR && TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST) { ptr = gimple_assign_rhs1 (stmt); extra_offset = BITS_PER_UNIT * int_cst_value (gimple_assign_rhs2 (stmt)); } } if (TREE_CODE (ptr) == ADDR_EXPR) { ref->base = get_addr_base_and_unit_offset (TREE_OPERAND (ptr, 0), &t); if (ref->base) ref->offset = BITS_PER_UNIT * t; else { size = NULL_TREE; ref->offset = 0; ref->base = get_base_address (TREE_OPERAND (ptr, 0)); } } else { ref->base = build2 (MEM_REF, char_type_node, ptr, null_pointer_node); ref->offset = 0; } ref->offset += extra_offset; if (size && tree_fits_shwi_p (size) && (size_hwi = tree_to_shwi (size)) <= HOST_WIDE_INT_MAX / BITS_PER_UNIT) ref->max_size = ref->size = size_hwi * BITS_PER_UNIT; else ref->max_size = ref->size = -1; ref->ref_alias_set = 0; ref->base_alias_set = 0; ref->volatile_p = false; } /* 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, alias_set_type ref1_alias_set, alias_set_type base1_alias_set, HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1, tree ref2, 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 base1, base2; tree type1, type2; tree *refp; int same_p; /* Choose bases and base types to search for. */ base1 = ref1; while (handled_component_p (base1)) base1 = TREE_OPERAND (base1, 0); type1 = TREE_TYPE (base1); base2 = ref2; while (handled_component_p (base2)) base2 = TREE_OPERAND (base2, 0); type2 = TREE_TYPE (base2); /* 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; bool reverse; get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp, &reverse); offset2 -= offadj; get_ref_base_and_extent (base1, &offadj, &sztmp, &msztmp, &reverse); offset1 -= 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; bool reverse; get_ref_base_and_extent (*refp, &offadj, &sztmp, &msztmp, &reverse); offset1 -= offadj; get_ref_base_and_extent (base2, &offadj, &sztmp, &msztmp, &reverse); offset2 -= 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 we can determine that component references REF1 and REF2, that are within a common DECL, cannot overlap. */ static bool nonoverlapping_component_refs_of_decl_p (tree ref1, tree ref2) { auto_vec component_refs1; auto_vec component_refs2; /* Create the stack of handled components for REF1. */ while (handled_component_p (ref1)) { component_refs1.safe_push (ref1); ref1 = TREE_OPERAND (ref1, 0); } if (TREE_CODE (ref1) == MEM_REF) { if (!integer_zerop (TREE_OPERAND (ref1, 1))) return false; ref1 = TREE_OPERAND (TREE_OPERAND (ref1, 0), 0); } /* Create the stack of handled components for REF2. */ while (handled_component_p (ref2)) { component_refs2.safe_push (ref2); ref2 = TREE_OPERAND (ref2, 0); } if (TREE_CODE (ref2) == MEM_REF) { if (!integer_zerop (TREE_OPERAND (ref2, 1))) return false; ref2 = TREE_OPERAND (TREE_OPERAND (ref2, 0), 0); } /* Bases must be either same or uncomparable. */ gcc_checking_assert (ref1 == ref2 || (DECL_P (ref1) && DECL_P (ref2) && compare_base_decls (ref1, ref2) != 0)); /* Pop the stacks in parallel and examine the COMPONENT_REFs of the same rank. This is sufficient because we start from the same DECL and you cannot reference several fields at a time with COMPONENT_REFs (unlike with ARRAY_RANGE_REFs for arrays) so you always need the same number of them to access a sub-component, unless you're in a union, in which case the return value will precisely be false. */ while (true) { do { if (component_refs1.is_empty ()) return false; ref1 = component_refs1.pop (); } while (!RECORD_OR_UNION_TYPE_P (TREE_TYPE (TREE_OPERAND (ref1, 0)))); do { if (component_refs2.is_empty ()) return false; ref2 = component_refs2.pop (); } while (!RECORD_OR_UNION_TYPE_P (TREE_TYPE (TREE_OPERAND (ref2, 0)))); /* Beware of BIT_FIELD_REF. */ if (TREE_CODE (ref1) != COMPONENT_REF || TREE_CODE (ref2) != COMPONENT_REF) return false; tree field1 = TREE_OPERAND (ref1, 1); tree field2 = TREE_OPERAND (ref2, 1); /* ??? We cannot simply use the type of operand #0 of the refs here as the Fortran compiler smuggles type punning into COMPONENT_REFs for common blocks instead of using unions like everyone else. */ tree type1 = DECL_CONTEXT (field1); tree type2 = DECL_CONTEXT (field2); /* We cannot disambiguate fields in a union or qualified union. */ if (type1 != type2 || TREE_CODE (type1) != RECORD_TYPE) return false; if (field1 != field2) { /* A field and its representative need to be considered the same. */ if (DECL_BIT_FIELD_REPRESENTATIVE (field1) == field2 || DECL_BIT_FIELD_REPRESENTATIVE (field2) == field1) return false; /* Different fields of the same record type cannot overlap. ??? Bitfields can overlap at RTL level so punt on them. */ if (DECL_BIT_FIELD (field1) && DECL_BIT_FIELD (field2)) return false; return true; } } return false; } /* qsort compare function to sort FIELD_DECLs after their DECL_FIELD_CONTEXT TYPE_UID. */ static inline int ncr_compar (const void *field1_, const void *field2_) { const_tree field1 = *(const_tree *) const_cast (field1_); const_tree field2 = *(const_tree *) const_cast (field2_); unsigned int uid1 = TYPE_UID (DECL_FIELD_CONTEXT (field1)); unsigned int uid2 = TYPE_UID (DECL_FIELD_CONTEXT (field2)); if (uid1 < uid2) return -1; else if (uid1 > uid2) return 1; return 0; } /* Return true if we can determine that the fields referenced cannot overlap for any pair of objects. */ static bool nonoverlapping_component_refs_p (const_tree x, const_tree y) { if (!flag_strict_aliasing || !x || !y || TREE_CODE (x) != COMPONENT_REF || TREE_CODE (y) != COMPONENT_REF) return false; auto_vec fieldsx; while (TREE_CODE (x) == COMPONENT_REF) { tree field = TREE_OPERAND (x, 1); tree type = DECL_FIELD_CONTEXT (field); if (TREE_CODE (type) == RECORD_TYPE) fieldsx.safe_push (field); x = TREE_OPERAND (x, 0); } if (fieldsx.length () == 0) return false; auto_vec fieldsy; while (TREE_CODE (y) == COMPONENT_REF) { tree field = TREE_OPERAND (y, 1); tree type = DECL_FIELD_CONTEXT (field); if (TREE_CODE (type) == RECORD_TYPE) fieldsy.safe_push (TREE_OPERAND (y, 1)); y = TREE_OPERAND (y, 0); } if (fieldsy.length () == 0) return false; /* Most common case first. */ if (fieldsx.length () == 1 && fieldsy.length () == 1) return ((DECL_FIELD_CONTEXT (fieldsx[0]) == DECL_FIELD_CONTEXT (fieldsy[0])) && fieldsx[0] != fieldsy[0] && !(DECL_BIT_FIELD (fieldsx[0]) && DECL_BIT_FIELD (fieldsy[0]))); if (fieldsx.length () == 2) { if (ncr_compar (&fieldsx[0], &fieldsx[1]) == 1) std::swap (fieldsx[0], fieldsx[1]); } else fieldsx.qsort (ncr_compar); if (fieldsy.length () == 2) { if (ncr_compar (&fieldsy[0], &fieldsy[1]) == 1) std::swap (fieldsy[0], fieldsy[1]); } else fieldsy.qsort (ncr_compar); unsigned i = 0, j = 0; do { const_tree fieldx = fieldsx[i]; const_tree fieldy = fieldsy[j]; tree typex = DECL_FIELD_CONTEXT (fieldx); tree typey = DECL_FIELD_CONTEXT (fieldy); if (typex == typey) { /* We're left with accessing different fields of a structure, no possible overlap. */ if (fieldx != fieldy) { /* A field and its representative need to be considered the same. */ if (DECL_BIT_FIELD_REPRESENTATIVE (fieldx) == fieldy || DECL_BIT_FIELD_REPRESENTATIVE (fieldy) == fieldx) return false; /* Different fields of the same record type cannot overlap. ??? Bitfields can overlap at RTL level so punt on them. */ if (DECL_BIT_FIELD (fieldx) && DECL_BIT_FIELD (fieldy)) return false; return true; } } if (TYPE_UID (typex) < TYPE_UID (typey)) { i++; if (i == fieldsx.length ()) break; } else { j++; if (j == fieldsy.length ()) break; } } while (1); 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. REF1 and REF2 if non-NULL are the complete memory reference trees. */ static bool decl_refs_may_alias_p (tree ref1, tree base1, HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1, tree ref2, tree base2, HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2) { gcc_checking_assert (DECL_P (base1) && DECL_P (base2)); /* If both references are based on different variables, they cannot alias. */ if (compare_base_decls (base1, base2) == 0) return false; /* If both references are based on the same variable, they cannot alias if the accesses do not overlap. */ if (!ranges_overlap_p (offset1, max_size1, offset2, max_size2)) return false; /* For components with variable position, the above test isn't sufficient, so we disambiguate component references manually. */ if (ref1 && ref2 && handled_component_p (ref1) && handled_component_p (ref2) && nonoverlapping_component_refs_of_decl_p (ref1, ref2)) return false; return true; } /* 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 ATTRIBUTE_UNUSED, tree base1, HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1 ATTRIBUTE_UNUSED, alias_set_type ref1_alias_set, alias_set_type base1_alias_set, tree ref2 ATTRIBUTE_UNUSED, tree base2, HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2, alias_set_type ref2_alias_set, alias_set_type base2_alias_set, bool tbaa_p) { tree ptr1; tree ptrtype1, dbase2; HOST_WIDE_INT offset1p = offset1, offset2p = offset2; HOST_WIDE_INT doffset1, doffset2; gcc_checking_assert ((TREE_CODE (base1) == MEM_REF || TREE_CODE (base1) == TARGET_MEM_REF) && DECL_P (base2)); ptr1 = TREE_OPERAND (base1, 0); /* The offset embedded in MEM_REFs can be negative. Bias them so that the resulting offset adjustment is positive. */ offset_int moff = mem_ref_offset (base1); moff <<= LOG2_BITS_PER_UNIT; if (wi::neg_p (moff)) offset2p += (-moff).to_short_addr (); else offset1p += moff.to_short_addr (); /* 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). ??? IVOPTs creates bases that do not honor this restriction, so do not apply this optimization for TARGET_MEM_REFs. */ if (TREE_CODE (base1) != TARGET_MEM_REF && !ranges_overlap_p (MAX (0, offset1p), -1, offset2p, max_size2)) return false; /* They also cannot alias if the pointer may not point to the decl. */ if (!ptr_deref_may_alias_decl_p (ptr1, base2)) return false; /* Disambiguations that rely on strict aliasing rules follow. */ if (!flag_strict_aliasing || !tbaa_p) return true; ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1)); /* If the alias set for a pointer access is zero all bets are off. */ if (base1_alias_set == 0) return true; /* When we are trying to disambiguate an access with a pointer dereference as base versus one with a decl as base we can use both the size of the decl and its dynamic type for extra disambiguation. ??? We do not know anything about the dynamic type of the decl other than that its alias-set contains base2_alias_set as a subset which does not help us here. */ /* As we know nothing useful about the dynamic type of the decl just use the usual conflict check rather than a subset test. ??? We could introduce -fvery-strict-aliasing when the language does not allow decls to have a dynamic type that differs from their static type. Then we can check !alias_set_subset_of (base1_alias_set, base2_alias_set) instead. */ if (base1_alias_set != base2_alias_set && !alias_sets_conflict_p (base1_alias_set, base2_alias_set)) return false; /* If the size of the access relevant for TBAA through the pointer is bigger than the size of the decl we can't possibly access the decl via that pointer. */ if (DECL_SIZE (base2) && COMPLETE_TYPE_P (TREE_TYPE (ptrtype1)) && TREE_CODE (DECL_SIZE (base2)) == INTEGER_CST && TREE_CODE (TYPE_SIZE (TREE_TYPE (ptrtype1))) == INTEGER_CST /* ??? This in turn may run afoul when a decl of type T which is a member of union type U is accessed through a pointer to type U and sizeof T is smaller than sizeof U. */ && TREE_CODE (TREE_TYPE (ptrtype1)) != UNION_TYPE && TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE && tree_int_cst_lt (DECL_SIZE (base2), TYPE_SIZE (TREE_TYPE (ptrtype1)))) return false; if (!ref2) return true; /* If the decl is accessed via a MEM_REF, reconstruct the base we can use for TBAA and an appropriately adjusted offset. */ dbase2 = ref2; while (handled_component_p (dbase2)) dbase2 = TREE_OPERAND (dbase2, 0); doffset1 = offset1; doffset2 = offset2; if (TREE_CODE (dbase2) == MEM_REF || TREE_CODE (dbase2) == TARGET_MEM_REF) { offset_int moff = mem_ref_offset (dbase2); moff <<= LOG2_BITS_PER_UNIT; if (wi::neg_p (moff)) doffset1 -= (-moff).to_short_addr (); else doffset2 -= moff.to_short_addr (); } /* If either reference is view-converted, give up now. */ if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1 || same_type_for_tbaa (TREE_TYPE (dbase2), TREE_TYPE (base2)) != 1) 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. For MEM_REFs we require that the component-ref offset we computed is relative to the start of the type which we ensure by comparing rvalue and access type and disregarding the constant pointer offset. */ if ((TREE_CODE (base1) != TARGET_MEM_REF || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1))) && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (dbase2)) == 1) return ranges_overlap_p (doffset1, max_size1, doffset2, max_size2); if (ref1 && ref2 && nonoverlapping_component_refs_p (ref1, ref2)) return false; /* Do access-path based disambiguation. */ if (ref1 && ref2 && (handled_component_p (ref1) || handled_component_p (ref2))) return aliasing_component_refs_p (ref1, ref1_alias_set, base1_alias_set, offset1, max_size1, ref2, 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 ATTRIBUTE_UNUSED, tree base1, HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1, alias_set_type ref1_alias_set, alias_set_type base1_alias_set, tree ref2 ATTRIBUTE_UNUSED, tree base2, HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2, alias_set_type ref2_alias_set, alias_set_type base2_alias_set, bool tbaa_p) { tree ptr1; tree ptr2; tree ptrtype1, ptrtype2; gcc_checking_assert ((TREE_CODE (base1) == MEM_REF || TREE_CODE (base1) == TARGET_MEM_REF) && (TREE_CODE (base2) == MEM_REF || TREE_CODE (base2) == TARGET_MEM_REF)); ptr1 = TREE_OPERAND (base1, 0); ptr2 = TREE_OPERAND (base2, 0); /* 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 ((!cfun || gimple_in_ssa_p (cfun)) && operand_equal_p (ptr1, ptr2, 0) && (((TREE_CODE (base1) != TARGET_MEM_REF || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1))) && (TREE_CODE (base2) != TARGET_MEM_REF || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2)))) || (TREE_CODE (base1) == TARGET_MEM_REF && TREE_CODE (base2) == TARGET_MEM_REF && (TMR_STEP (base1) == TMR_STEP (base2) || (TMR_STEP (base1) && TMR_STEP (base2) && operand_equal_p (TMR_STEP (base1), TMR_STEP (base2), 0))) && (TMR_INDEX (base1) == TMR_INDEX (base2) || (TMR_INDEX (base1) && TMR_INDEX (base2) && operand_equal_p (TMR_INDEX (base1), TMR_INDEX (base2), 0))) && (TMR_INDEX2 (base1) == TMR_INDEX2 (base2) || (TMR_INDEX2 (base1) && TMR_INDEX2 (base2) && operand_equal_p (TMR_INDEX2 (base1), TMR_INDEX2 (base2), 0)))))) { offset_int moff; /* The offset embedded in MEM_REFs can be negative. Bias them so that the resulting offset adjustment is positive. */ moff = mem_ref_offset (base1); moff <<= LOG2_BITS_PER_UNIT; if (wi::neg_p (moff)) offset2 += (-moff).to_short_addr (); else offset1 += moff.to_shwi (); moff = mem_ref_offset (base2); moff <<= LOG2_BITS_PER_UNIT; if (wi::neg_p (moff)) offset1 += (-moff).to_short_addr (); else offset2 += moff.to_short_addr (); 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 || !tbaa_p) return true; ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1)); ptrtype2 = TREE_TYPE (TREE_OPERAND (base2, 1)); /* If the alias set for a pointer access is zero all bets are off. */ if (base1_alias_set == 0 || 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 ((TREE_CODE (base1) != TARGET_MEM_REF || (!TMR_INDEX (base1) && !TMR_INDEX2 (base1))) && (TREE_CODE (base2) != TARGET_MEM_REF || (!TMR_INDEX (base2) && !TMR_INDEX2 (base2))) && same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) == 1 && same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) == 1 && same_type_for_tbaa (TREE_TYPE (ptrtype1), TREE_TYPE (ptrtype2)) == 1 /* But avoid treating arrays as "objects", instead assume they can overlap by an exact multiple of their element size. */ && TREE_CODE (TREE_TYPE (ptrtype1)) != ARRAY_TYPE) 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; /* If either reference is view-converted, give up now. */ if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1 || same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) != 1) return true; if (ref1 && ref2 && nonoverlapping_component_refs_p (ref1, ref2)) return false; /* Do access-path based disambiguation. */ if (ref1 && ref2 && (handled_component_p (ref1) || handled_component_p (ref2))) return aliasing_component_refs_p (ref1, ref1_alias_set, base1_alias_set, offset1, max_size1, ref2, 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; gcc_checking_assert ((!ref1->ref || TREE_CODE (ref1->ref) == SSA_NAME || DECL_P (ref1->ref) || TREE_CODE (ref1->ref) == STRING_CST || handled_component_p (ref1->ref) || TREE_CODE (ref1->ref) == MEM_REF || TREE_CODE (ref1->ref) == TARGET_MEM_REF) && (!ref2->ref || TREE_CODE (ref2->ref) == SSA_NAME || DECL_P (ref2->ref) || TREE_CODE (ref2->ref) == STRING_CST || handled_component_p (ref2->ref) || TREE_CODE (ref2->ref) == MEM_REF || TREE_CODE (ref2->ref) == TARGET_MEM_REF)); /* 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 (base1) == CONST_DECL || TREE_CODE (base1) == CONSTRUCTOR || TREE_CODE (base1) == ADDR_EXPR || CONSTANT_CLASS_P (base1) || TREE_CODE (base2) == SSA_NAME || TREE_CODE (base2) == CONST_DECL || TREE_CODE (base2) == CONSTRUCTOR || TREE_CODE (base2) == ADDR_EXPR || CONSTANT_CLASS_P (base2)) return false; /* We can end up referring to code via function and label decls. As we likely do not properly track code aliases conservatively bail out. */ if (TREE_CODE (base1) == FUNCTION_DECL || TREE_CODE (base1) == LABEL_DECL || TREE_CODE (base2) == FUNCTION_DECL || TREE_CODE (base2) == LABEL_DECL) return true; /* Two volatile accesses always conflict. */ if (ref1->volatile_p && ref2->volatile_p) 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 = DECL_P (base1); var2_p = DECL_P (base2); if (var1_p && var2_p) return decl_refs_may_alias_p (ref1->ref, base1, offset1, max_size1, ref2->ref, base2, offset2, max_size2); /* Handle restrict based accesses. ??? ao_ref_base strips inner MEM_REF [&decl], recover from that here. */ tree rbase1 = base1; tree rbase2 = base2; if (var1_p) { rbase1 = ref1->ref; if (rbase1) while (handled_component_p (rbase1)) rbase1 = TREE_OPERAND (rbase1, 0); } if (var2_p) { rbase2 = ref2->ref; if (rbase2) while (handled_component_p (rbase2)) rbase2 = TREE_OPERAND (rbase2, 0); } if (rbase1 && rbase2 && (TREE_CODE (base1) == MEM_REF || TREE_CODE (base1) == TARGET_MEM_REF) && (TREE_CODE (base2) == MEM_REF || TREE_CODE (base2) == TARGET_MEM_REF) /* If the accesses are in the same restrict clique... */ && MR_DEPENDENCE_CLIQUE (base1) == MR_DEPENDENCE_CLIQUE (base2) /* But based on different pointers they do not alias. */ && MR_DEPENDENCE_BASE (base1) != MR_DEPENDENCE_BASE (base2)) return false; ind1_p = (TREE_CODE (base1) == MEM_REF || TREE_CODE (base1) == TARGET_MEM_REF); ind2_p = (TREE_CODE (base2) == MEM_REF || TREE_CODE (base2) == TARGET_MEM_REF); /* Canonicalize the pointer-vs-decl case. */ if (ind1_p && var2_p) { std::swap (offset1, offset2); std::swap (max_size1, max_size2); std::swap (base1, base2); std::swap (ref1, ref2); var1_p = true; ind1_p = false; var2_p = false; ind2_p = true; } /* 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; /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */ if (var1_p && ind2_p) return indirect_ref_may_alias_decl_p (ref2->ref, base2, offset2, max_size2, ao_ref_alias_set (ref2), ao_ref_base_alias_set (ref2), ref1->ref, base1, offset1, max_size1, ao_ref_alias_set (ref1), ao_ref_base_alias_set (ref1), tbaa_p); else if (ind1_p && ind2_p) return indirect_refs_may_alias_p (ref1->ref, base1, offset1, max_size1, ao_ref_alias_set (ref1), ao_ref_base_alias_set (ref1), ref2->ref, base2, offset2, max_size2, ao_ref_alias_set (ref2), ao_ref_base_alias_set (ref2), tbaa_p); gcc_unreachable (); } static bool refs_may_alias_p (tree ref1, ao_ref *ref2) { ao_ref r1; ao_ref_init (&r1, ref1); return refs_may_alias_p_1 (&r1, ref2, true); } 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 (gcall *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; /* A call that is not without side-effects might involve volatile accesses and thus conflicts with all other volatile accesses. */ if (ref->volatile_p) 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 && gimple_call_builtin_p (call, BUILT_IN_NORMAL)) switch (DECL_FUNCTION_CODE (callee)) { /* All the following functions read memory pointed to by their second argument. strcat/strncat additionally reads memory pointed to by the first argument. */ case BUILT_IN_STRCAT: case BUILT_IN_STRNCAT: { ao_ref dref; ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 0), NULL_TREE); if (refs_may_alias_p_1 (&dref, ref, false)) return true; } /* FALLTHRU */ 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_TM_MEMCPY: case BUILT_IN_TM_MEMMOVE: { 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_STRCAT_CHK: case BUILT_IN_STRNCAT_CHK: { ao_ref dref; ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 0), NULL_TREE); if (refs_may_alias_p_1 (&dref, ref, false)) return true; } /* FALLTHRU */ case BUILT_IN_STRCPY_CHK: case BUILT_IN_STRNCPY_CHK: case BUILT_IN_MEMCPY_CHK: case BUILT_IN_MEMMOVE_CHK: case BUILT_IN_MEMPCPY_CHK: case BUILT_IN_STPCPY_CHK: case BUILT_IN_STPNCPY_CHK: { ao_ref dref; tree size = NULL_TREE; if (gimple_call_num_args (call) == 4) 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 functions read memory pointed to by their first argument. */ CASE_BUILT_IN_TM_LOAD (1): CASE_BUILT_IN_TM_LOAD (2): CASE_BUILT_IN_TM_LOAD (4): CASE_BUILT_IN_TM_LOAD (8): CASE_BUILT_IN_TM_LOAD (FLOAT): CASE_BUILT_IN_TM_LOAD (DOUBLE): CASE_BUILT_IN_TM_LOAD (LDOUBLE): CASE_BUILT_IN_TM_LOAD (M64): CASE_BUILT_IN_TM_LOAD (M128): CASE_BUILT_IN_TM_LOAD (M256): case BUILT_IN_TM_LOG: case BUILT_IN_TM_LOG_1: case BUILT_IN_TM_LOG_2: case BUILT_IN_TM_LOG_4: case BUILT_IN_TM_LOG_8: case BUILT_IN_TM_LOG_FLOAT: case BUILT_IN_TM_LOG_DOUBLE: case BUILT_IN_TM_LOG_LDOUBLE: case BUILT_IN_TM_LOG_M64: case BUILT_IN_TM_LOG_M128: case BUILT_IN_TM_LOG_M256: return ptr_deref_may_alias_ref_p_1 (gimple_call_arg (call, 0), ref); /* These read memory pointed to by the first argument. */ case BUILT_IN_STRDUP: case BUILT_IN_STRNDUP: case BUILT_IN_REALLOC: { ao_ref dref; tree size = NULL_TREE; if (gimple_call_num_args (call) == 2) size = gimple_call_arg (call, 1); ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 0), size); return refs_may_alias_p_1 (&dref, ref, false); } /* These read memory pointed to by the first argument. */ case BUILT_IN_INDEX: case BUILT_IN_STRCHR: case BUILT_IN_STRRCHR: { ao_ref dref; ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 0), NULL_TREE); return refs_may_alias_p_1 (&dref, ref, false); } /* These read memory pointed to by the first argument with size in the third argument. */ case BUILT_IN_MEMCHR: { ao_ref dref; ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 0), gimple_call_arg (call, 2)); return refs_may_alias_p_1 (&dref, ref, false); } /* These read memory pointed to by the first and second arguments. */ case BUILT_IN_STRSTR: case BUILT_IN_STRPBRK: { ao_ref dref; ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 0), NULL_TREE); if (refs_may_alias_p_1 (&dref, ref, false)) return true; ao_ref_init_from_ptr_and_size (&dref, gimple_call_arg (call, 1), NULL_TREE); 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_POSIX_MEMALIGN: case BUILT_IN_ALIGNED_ALLOC: case BUILT_IN_CALLOC: case BUILT_IN_ALLOCA: case BUILT_IN_ALLOCA_WITH_ALIGN: case BUILT_IN_STACK_SAVE: case BUILT_IN_STACK_RESTORE: case BUILT_IN_MEMSET: case BUILT_IN_TM_MEMSET: case BUILT_IN_MEMSET_CHK: 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: case BUILT_IN_ASSUME_ALIGNED: case BUILT_IN_VA_END: return false; /* __sync_* builtins and some OpenMP builtins act as threading barriers. */ #undef DEF_SYNC_BUILTIN #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM: #include "sync-builtins.def" #undef DEF_SYNC_BUILTIN case BUILT_IN_GOMP_ATOMIC_START: case BUILT_IN_GOMP_ATOMIC_END: case BUILT_IN_GOMP_BARRIER: case BUILT_IN_GOMP_BARRIER_CANCEL: case BUILT_IN_GOMP_TASKWAIT: case BUILT_IN_GOMP_TASKGROUP_END: case BUILT_IN_GOMP_CRITICAL_START: case BUILT_IN_GOMP_CRITICAL_END: case BUILT_IN_GOMP_CRITICAL_NAME_START: case BUILT_IN_GOMP_CRITICAL_NAME_END: case BUILT_IN_GOMP_LOOP_END: case BUILT_IN_GOMP_LOOP_END_CANCEL: case BUILT_IN_GOMP_ORDERED_START: case BUILT_IN_GOMP_ORDERED_END: case BUILT_IN_GOMP_SECTIONS_END: case BUILT_IN_GOMP_SECTIONS_END_CANCEL: case BUILT_IN_GOMP_SINGLE_COPY_START: case BUILT_IN_GOMP_SINGLE_COPY_END: return true; default: /* Fallthru to general call handling. */; } /* Check if base is a global static variable that is not read by the function. */ if (callee != NULL_TREE && VAR_P (base) && TREE_STATIC (base)) { struct cgraph_node *node = cgraph_node::get (callee); bitmap not_read; /* FIXME: Callee can be an OMP builtin that does not have a call graph node yet. We should enforce that there are nodes for all decls in the IL and remove this check instead. */ if (node && (not_read = ipa_reference_get_not_read_global (node)) && bitmap_bit_p (not_read, ipa_reference_var_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 ((TREE_CODE (base) == MEM_REF || TREE_CODE (base) == TARGET_MEM_REF) && 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 (gcall *call, ao_ref *ref) { bool res; res = ref_maybe_used_by_call_p_1 (call, ref); 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, ao_ref *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 (as_a (stmt), ref); else if (greturn *return_stmt = dyn_cast (stmt)) { tree retval = gimple_return_retval (return_stmt); if (retval && TREE_CODE (retval) != SSA_NAME && !is_gimple_min_invariant (retval) && refs_may_alias_p (retval, ref)) return true; /* If ref escapes the function then the return acts as a use. */ tree base = ao_ref_base (ref); if (!base) ; else if (DECL_P (base)) return is_global_var (base); else if (TREE_CODE (base) == MEM_REF || TREE_CODE (base) == TARGET_MEM_REF) return ptr_deref_may_alias_global_p (TREE_OPERAND (base, 0)); return false; } return true; } bool ref_maybe_used_by_stmt_p (gimple *stmt, tree ref) { ao_ref r; ao_ref_init (&r, ref); return ref_maybe_used_by_stmt_p (stmt, &r); } /* If the call in statement CALL may clobber the memory reference REF return true, otherwise return false. */ bool call_may_clobber_ref_p_1 (gcall *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; if (gimple_call_internal_p (call)) switch (gimple_call_internal_fn (call)) { /* Treat these internal calls like ECF_PURE for aliasing, they don't write to any memory the program should care about. They have important other side-effects, and read memory, so can't be ECF_NOVOPS. */ case IFN_UBSAN_NULL: case IFN_UBSAN_BOUNDS: case IFN_UBSAN_VPTR: case IFN_UBSAN_OBJECT_SIZE: case IFN_ASAN_CHECK: return false; default: break; } base = ao_ref_base (ref); if (!base) return true; if (TREE_CODE (base) == SSA_NAME || CONSTANT_CLASS_P (base)) return false; /* A call that is not without side-effects might involve volatile accesses and thus conflicts with all other volatile accesses. */ if (ref->volatile_p) return true; /* 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 && gimple_call_builtin_p (call, 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: case BUILT_IN_TM_MEMSET: CASE_BUILT_IN_TM_STORE (1): CASE_BUILT_IN_TM_STORE (2): CASE_BUILT_IN_TM_STORE (4): CASE_BUILT_IN_TM_STORE (8): CASE_BUILT_IN_TM_STORE (FLOAT): CASE_BUILT_IN_TM_STORE (DOUBLE): CASE_BUILT_IN_TM_STORE (LDOUBLE): CASE_BUILT_IN_TM_STORE (M64): CASE_BUILT_IN_TM_STORE (M128): CASE_BUILT_IN_TM_STORE (M256): case BUILT_IN_TM_MEMCPY: case BUILT_IN_TM_MEMMOVE: { ao_ref dref; tree size = NULL_TREE; /* Don't pass in size for strncat, as the maximum size is strlen (dest) + n + 1 instead of n, resp. n + 1 at dest + strlen (dest), but strlen (dest) isn't known. */ if (gimple_call_num_args (call) == 3 && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT) 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_STRCPY_CHK: case BUILT_IN_STRNCPY_CHK: case BUILT_IN_MEMCPY_CHK: case BUILT_IN_MEMMOVE_CHK: case BUILT_IN_MEMPCPY_CHK: case BUILT_IN_STPCPY_CHK: case BUILT_IN_STPNCPY_CHK: case BUILT_IN_STRCAT_CHK: case BUILT_IN_STRNCAT_CHK: case BUILT_IN_MEMSET_CHK: { ao_ref dref; tree size = NULL_TREE; /* Don't pass in size for __strncat_chk, as the maximum size is strlen (dest) + n + 1 instead of n, resp. n + 1 at dest + strlen (dest), but strlen (dest) isn't known. */ if (gimple_call_num_args (call) == 4 && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT_CHK) 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_ALIGNED_ALLOC: case BUILT_IN_CALLOC: case BUILT_IN_STRDUP: case BUILT_IN_STRNDUP: /* Unix98 specifies that errno is set on allocation failure. */ if (flag_errno_math && targetm.ref_may_alias_errno (ref)) return true; return false; case BUILT_IN_STACK_SAVE: case BUILT_IN_ALLOCA: case BUILT_IN_ALLOCA_WITH_ALIGN: case BUILT_IN_ASSUME_ALIGNED: return false; /* But posix_memalign stores a pointer into the memory pointed to by its first argument. */ case BUILT_IN_POSIX_MEMALIGN: { tree ptrptr = gimple_call_arg (call, 0); ao_ref dref; ao_ref_init_from_ptr_and_size (&dref, ptrptr, TYPE_SIZE_UNIT (ptr_type_node)); return (refs_may_alias_p_1 (&dref, ref, false) || (flag_errno_math && targetm.ref_may_alias_errno (ref))); } /* 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: case BUILT_IN_VA_END: { tree ptr = gimple_call_arg (call, 0); return ptr_deref_may_alias_ref_p_1 (ptr, ref); } /* Realloc serves both as allocation point and deallocation point. */ case BUILT_IN_REALLOC: { tree ptr = gimple_call_arg (call, 0); /* Unix98 specifies that errno is set on allocation failure. */ return ((flag_errno_math && targetm.ref_may_alias_errno (ref)) || 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)); } /* __sync_* builtins and some OpenMP builtins act as threading barriers. */ #undef DEF_SYNC_BUILTIN #define DEF_SYNC_BUILTIN(ENUM, NAME, TYPE, ATTRS) case ENUM: #include "sync-builtins.def" #undef DEF_SYNC_BUILTIN case BUILT_IN_GOMP_ATOMIC_START: case BUILT_IN_GOMP_ATOMIC_END: case BUILT_IN_GOMP_BARRIER: case BUILT_IN_GOMP_BARRIER_CANCEL: case BUILT_IN_GOMP_TASKWAIT: case BUILT_IN_GOMP_TASKGROUP_END: case BUILT_IN_GOMP_CRITICAL_START: case BUILT_IN_GOMP_CRITICAL_END: case BUILT_IN_GOMP_CRITICAL_NAME_START: case BUILT_IN_GOMP_CRITICAL_NAME_END: case BUILT_IN_GOMP_LOOP_END: case BUILT_IN_GOMP_LOOP_END_CANCEL: case BUILT_IN_GOMP_ORDERED_START: case BUILT_IN_GOMP_ORDERED_END: case BUILT_IN_GOMP_SECTIONS_END: case BUILT_IN_GOMP_SECTIONS_END_CANCEL: case BUILT_IN_GOMP_SINGLE_COPY_START: case BUILT_IN_GOMP_SINGLE_COPY_END: return true; 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 && VAR_P (base) && TREE_STATIC (base)) { struct cgraph_node *node = cgraph_node::get (callee); bitmap not_written; if (node && (not_written = ipa_reference_get_not_written_global (node)) && bitmap_bit_p (not_written, ipa_reference_var_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 ((TREE_CODE (base) == MEM_REF || TREE_CODE (base) == TARGET_MEM_REF) && 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 (gcall *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 && TREE_CODE (lhs) != SSA_NAME) { 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 (as_a (stmt), ref); } else if (gimple_assign_single_p (stmt)) { tree lhs = gimple_assign_lhs (stmt); if (TREE_CODE (lhs) != SSA_NAME) { ao_ref r; ao_ref_init (&r, lhs); 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); } /* Return true if store1 and store2 described by corresponding tuples have the same size and store to the same address. */ static bool same_addr_size_stores_p (tree base1, HOST_WIDE_INT offset1, HOST_WIDE_INT size1, HOST_WIDE_INT max_size1, tree base2, HOST_WIDE_INT offset2, HOST_WIDE_INT size2, HOST_WIDE_INT max_size2) { /* Offsets need to be 0. */ if (offset1 != 0 || offset2 != 0) return false; bool base1_obj_p = SSA_VAR_P (base1); bool base2_obj_p = SSA_VAR_P (base2); /* We need one object. */ if (base1_obj_p == base2_obj_p) return false; tree obj = base1_obj_p ? base1 : base2; /* And we need one MEM_REF. */ bool base1_memref_p = TREE_CODE (base1) == MEM_REF; bool base2_memref_p = TREE_CODE (base2) == MEM_REF; if (base1_memref_p == base2_memref_p) return false; tree memref = base1_memref_p ? base1 : base2; /* Sizes need to be valid. */ if (max_size1 == -1 || max_size2 == -1 || size1 == -1 || size2 == -1) return false; /* Max_size needs to match size. */ if (max_size1 != size1 || max_size2 != size2) return false; /* Sizes need to match. */ if (size1 != size2) return false; /* Check that memref is a store to pointer with singleton points-to info. */ if (!integer_zerop (TREE_OPERAND (memref, 1))) return false; tree ptr = TREE_OPERAND (memref, 0); if (TREE_CODE (ptr) != SSA_NAME) return false; struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr); unsigned int pt_uid; if (pi == NULL || !pt_solution_singleton_or_null_p (&pi->pt, &pt_uid)) return false; /* Be conservative with non-call exceptions when the address might be NULL. */ if (flag_non_call_exceptions && pi->pt.null) return false; /* Check that ptr points relative to obj. */ unsigned int obj_uid = DECL_PT_UID (obj); if (obj_uid != pt_uid) return false; /* Check that the object size is the same as the store size. That ensures us that ptr points to the start of obj. */ if (!tree_fits_shwi_p (DECL_SIZE (obj))) return false; HOST_WIDE_INT obj_size = tree_to_shwi (DECL_SIZE (obj)); return obj_size == size1; } /* If STMT kills the memory reference REF return true, otherwise return false. */ bool stmt_kills_ref_p (gimple *stmt, ao_ref *ref) { if (!ao_ref_base (ref)) return false; if (gimple_has_lhs (stmt) && TREE_CODE (gimple_get_lhs (stmt)) != SSA_NAME /* The assignment is not necessarily carried out if it can throw and we can catch it in the current function where we could inspect the previous value. ??? We only need to care about the RHS throwing. For aggregate assignments or similar calls and non-call exceptions the LHS might throw as well. */ && !stmt_can_throw_internal (stmt)) { tree lhs = gimple_get_lhs (stmt); /* If LHS is literally a base of the access we are done. */ if (ref->ref) { tree base = ref->ref; if (handled_component_p (base)) { tree saved_lhs0 = NULL_TREE; if (handled_component_p (lhs)) { saved_lhs0 = TREE_OPERAND (lhs, 0); TREE_OPERAND (lhs, 0) = integer_zero_node; } do { /* Just compare the outermost handled component, if they are equal we have found a possible common base. */ tree saved_base0 = TREE_OPERAND (base, 0); TREE_OPERAND (base, 0) = integer_zero_node; bool res = operand_equal_p (lhs, base, 0); TREE_OPERAND (base, 0) = saved_base0; if (res) break; /* Otherwise drop handled components of the access. */ base = saved_base0; } while (handled_component_p (base)); if (saved_lhs0) TREE_OPERAND (lhs, 0) = saved_lhs0; } /* Finally check if the lhs has the same address and size as the base candidate of the access. */ if (lhs == base || (((TYPE_SIZE (TREE_TYPE (lhs)) == TYPE_SIZE (TREE_TYPE (base))) || (TYPE_SIZE (TREE_TYPE (lhs)) && TYPE_SIZE (TREE_TYPE (base)) && operand_equal_p (TYPE_SIZE (TREE_TYPE (lhs)), TYPE_SIZE (TREE_TYPE (base)), 0))) && operand_equal_p (lhs, base, OEP_ADDRESS_OF))) return true; } /* Now look for non-literal equal bases with the restriction of handling constant offset and size. */ /* For a must-alias check we need to be able to constrain the access properly. */ if (ref->max_size == -1) return false; HOST_WIDE_INT size, offset, max_size, ref_offset = ref->offset; bool reverse; tree base = get_ref_base_and_extent (lhs, &offset, &size, &max_size, &reverse); /* We can get MEM[symbol: sZ, index: D.8862_1] here, so base == ref->base does not always hold. */ if (base != ref->base) { /* Try using points-to info. */ if (same_addr_size_stores_p (base, offset, size, max_size, ref->base, ref->offset, ref->size, ref->max_size)) return true; /* If both base and ref->base are MEM_REFs, only compare the first operand, and if the second operand isn't equal constant, try to add the offsets into offset and ref_offset. */ if (TREE_CODE (base) == MEM_REF && TREE_CODE (ref->base) == MEM_REF && TREE_OPERAND (base, 0) == TREE_OPERAND (ref->base, 0)) { if (!tree_int_cst_equal (TREE_OPERAND (base, 1), TREE_OPERAND (ref->base, 1))) { offset_int off1 = mem_ref_offset (base); off1 <<= LOG2_BITS_PER_UNIT; off1 += offset; offset_int off2 = mem_ref_offset (ref->base); off2 <<= LOG2_BITS_PER_UNIT; off2 += ref_offset; if (wi::fits_shwi_p (off1) && wi::fits_shwi_p (off2)) { offset = off1.to_shwi (); ref_offset = off2.to_shwi (); } else size = -1; } } else size = -1; } /* For a must-alias check we need to be able to constrain the access properly. */ if (size != -1 && size == max_size) { if (offset <= ref_offset && offset + size >= ref_offset + ref->max_size) return true; } } if (is_gimple_call (stmt)) { tree callee = gimple_call_fndecl (stmt); if (callee != NULL_TREE && gimple_call_builtin_p (stmt, BUILT_IN_NORMAL)) switch (DECL_FUNCTION_CODE (callee)) { case BUILT_IN_FREE: { tree ptr = gimple_call_arg (stmt, 0); tree base = ao_ref_base (ref); if (base && TREE_CODE (base) == MEM_REF && TREE_OPERAND (base, 0) == ptr) return true; break; } case BUILT_IN_MEMCPY: case BUILT_IN_MEMPCPY: case BUILT_IN_MEMMOVE: case BUILT_IN_MEMSET: case BUILT_IN_MEMCPY_CHK: case BUILT_IN_MEMPCPY_CHK: case BUILT_IN_MEMMOVE_CHK: case BUILT_IN_MEMSET_CHK: case BUILT_IN_STRNCPY: case BUILT_IN_STPNCPY: { /* For a must-alias check we need to be able to constrain the access properly. */ if (ref->max_size == -1) return false; tree dest = gimple_call_arg (stmt, 0); tree len = gimple_call_arg (stmt, 2); if (!tree_fits_shwi_p (len)) return false; tree rbase = ref->base; offset_int roffset = ref->offset; ao_ref dref; ao_ref_init_from_ptr_and_size (&dref, dest, len); tree base = ao_ref_base (&dref); offset_int offset = dref.offset; if (!base || dref.size == -1) return false; if (TREE_CODE (base) == MEM_REF) { if (TREE_CODE (rbase) != MEM_REF) return false; // Compare pointers. offset += mem_ref_offset (base) << LOG2_BITS_PER_UNIT; roffset += mem_ref_offset (rbase) << LOG2_BITS_PER_UNIT; base = TREE_OPERAND (base, 0); rbase = TREE_OPERAND (rbase, 0); } if (base == rbase && offset <= roffset && (roffset + ref->max_size <= offset + (wi::to_offset (len) << LOG2_BITS_PER_UNIT))) return true; break; } case BUILT_IN_VA_END: { tree ptr = gimple_call_arg (stmt, 0); if (TREE_CODE (ptr) == ADDR_EXPR) { tree base = ao_ref_base (ref); if (TREE_OPERAND (ptr, 0) == base) return true; } break; } default:; } } return false; } bool stmt_kills_ref_p (gimple *stmt, tree ref) { ao_ref r; ao_ref_init (&r, ref); return stmt_kills_ref_p (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, unsigned int *cnt, bitmap *visited, bool abort_on_visited, void *(*translate)(ao_ref *, tree, void *, bool *), void *data) { basic_block bb = gimple_bb (phi); 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 !abort_on_visited; vuse = get_continuation_for_phi (def_stmt, ref, cnt, visited, abort_on_visited, translate, data); if (!vuse) return false; continue; } else if (gimple_nop_p (def_stmt)) return false; else { /* A clobbering statement or the end of the IL ends it failing. */ ++*cnt; if (stmt_may_clobber_ref_p_1 (def_stmt, ref)) { bool disambiguate_only = true; if (translate && (*translate) (ref, vuse, data, &disambiguate_only) == NULL) ; else return false; } } /* If we reach a new basic-block see if we already skipped it in a previous walk that ended successfully. */ if (gimple_bb (def_stmt) != bb) { if (!bitmap_set_bit (*visited, SSA_NAME_VERSION (vuse))) return !abort_on_visited; bb = gimple_bb (def_stmt); } 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. Increments *CNT for each alias disambiguation done. Returns NULL_TREE if no suitable virtual operand can be found. */ tree get_continuation_for_phi (gimple *phi, ao_ref *ref, unsigned int *cnt, bitmap *visited, bool abort_on_visited, void *(*translate)(ao_ref *, tree, void *, bool *), void *data) { 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 or more arguments try to pairwise skip non-aliasing code until we hit the phi argument definition that dominates the other one. */ basic_block phi_bb = gimple_bb (phi); tree arg0, arg1; unsigned i; /* Find a candidate for the virtual operand which definition dominates those of all others. */ /* First look if any of the args themselves satisfy this. */ for (i = 0; i < nargs; ++i) { arg0 = PHI_ARG_DEF (phi, i); if (SSA_NAME_IS_DEFAULT_DEF (arg0)) break; basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (arg0)); if (def_bb != phi_bb && dominated_by_p (CDI_DOMINATORS, phi_bb, def_bb)) break; arg0 = NULL_TREE; } /* If not, look if we can reach such candidate by walking defs of a PHI arg without crossing other PHIs. */ if (! arg0) for (i = 0; i < nargs; ++i) { arg0 = PHI_ARG_DEF (phi, i); gimple *def = SSA_NAME_DEF_STMT (arg0); /* Backedges can't work. */ if (dominated_by_p (CDI_DOMINATORS, gimple_bb (def), phi_bb)) continue; /* See below. */ if (gimple_code (def) == GIMPLE_PHI) continue; while (! dominated_by_p (CDI_DOMINATORS, phi_bb, gimple_bb (def))) { arg0 = gimple_vuse (def); if (SSA_NAME_IS_DEFAULT_DEF (arg0)) break; def = SSA_NAME_DEF_STMT (arg0); if (gimple_code (def) == GIMPLE_PHI) { /* Do not try to look through arbitrarily complicated CFGs. For those looking for the first VUSE starting from the end of the immediate dominator of phi_bb is likely faster. */ arg0 = NULL_TREE; goto next; } } break; next:; } if (! arg0) return NULL_TREE; /* Then check against the found candidate. */ for (i = 0; i < nargs; ++i) { arg1 = PHI_ARG_DEF (phi, i); if (arg1 == arg0) ; else if (! maybe_skip_until (phi, arg0, ref, arg1, cnt, visited, abort_on_visited, translate, data)) return NULL_TREE; } return arg0; } /* 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. VALUEIZE if non-NULL is called with the next VUSE that is considered and return value is substituted for that. This can be used to implement optimistic value-numbering for example. Note that the VUSE argument is assumed to be valueized already. 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, unsigned int, void *), void *(*translate)(ao_ref *, tree, void *, bool *), tree (*valueize)(tree), void *data) { bitmap visited = NULL; void *res; unsigned int cnt = 0; bool translated = false; 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, cnt, data); /* Abort walk. */ if (res == (void *)-1) { res = NULL; break; } /* Lookup succeeded. */ else if (res != NULL) break; if (valueize) vuse = valueize (vuse); 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, &cnt, &visited, translated, translate, data); else { cnt++; if (stmt_may_clobber_ref_p_1 (def_stmt, ref)) { if (!translate) break; bool disambiguate_only = false; res = (*translate) (ref, vuse, data, &disambiguate_only); /* Failed lookup and translation. */ if (res == (void *)-1) { res = NULL; break; } /* Lookup succeeded. */ else if (res != NULL) break; /* Translation succeeded, continue walking. */ translated = translated || !disambiguate_only; } 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. If function entry is reached, FUNCTION_ENTRY_REACHED is set to true. The pointer may be NULL and then we do not track this information. 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 or -1 if LIMIT stmts were walked and the walk was aborted at this point. If LIMIT is zero the walk is not aborted. */ static int walk_aliased_vdefs_1 (ao_ref *ref, tree vdef, bool (*walker)(ao_ref *, tree, void *), void *data, bitmap *visited, unsigned int cnt, bool *function_entry_reached, unsigned limit) { 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)) { if (function_entry_reached) *function_entry_reached = true; 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) { int res = walk_aliased_vdefs_1 (ref, gimple_phi_arg_def (def_stmt, i), walker, data, visited, cnt, function_entry_reached, limit); if (res == -1) return -1; cnt = res; } return cnt; } /* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */ cnt++; if (cnt == limit) return -1; if ((!ref || stmt_may_clobber_ref_p_1 (def_stmt, ref)) && (*walker) (ref, vdef, data)) return cnt; vdef = gimple_vuse (def_stmt); } while (1); } int walk_aliased_vdefs (ao_ref *ref, tree vdef, bool (*walker)(ao_ref *, tree, void *), void *data, bitmap *visited, bool *function_entry_reached, unsigned int limit) { bitmap local_visited = NULL; int ret; timevar_push (TV_ALIAS_STMT_WALK); if (function_entry_reached) *function_entry_reached = false; ret = walk_aliased_vdefs_1 (ref, vdef, walker, data, visited ? visited : &local_visited, 0, function_entry_reached, limit); if (local_visited) BITMAP_FREE (local_visited); timevar_pop (TV_ALIAS_STMT_WALK); return ret; }