/* Alias analysis for trees.
- Copyright (C) 2004-2018 Free Software Foundation, Inc.
+ Copyright (C) 2004-2020 Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>
This file is part of GCC.
#include "tree-dfa.h"
#include "ipa-reference.h"
#include "varasm.h"
+#include "ipa-modref-tree.h"
+#include "ipa-modref.h"
/* Broad overview of how alias analysis on gimple works:
this file. Low-level disambiguators dealing with points-to
information are in tree-ssa-structalias.c. */
+static int nonoverlapping_refs_since_match_p (tree, tree, tree, tree, bool);
+static bool nonoverlapping_component_refs_p (const_tree, const_tree);
/* Query statistics for the different low-level disambiguators.
A high-level query may trigger multiple of them. */
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;
+ unsigned HOST_WIDE_INT aliasing_component_refs_p_may_alias;
+ unsigned HOST_WIDE_INT aliasing_component_refs_p_no_alias;
+ unsigned HOST_WIDE_INT nonoverlapping_component_refs_p_may_alias;
+ unsigned HOST_WIDE_INT nonoverlapping_component_refs_p_no_alias;
+ unsigned HOST_WIDE_INT nonoverlapping_refs_since_match_p_may_alias;
+ unsigned HOST_WIDE_INT nonoverlapping_refs_since_match_p_must_overlap;
+ unsigned HOST_WIDE_INT nonoverlapping_refs_since_match_p_no_alias;
+ unsigned HOST_WIDE_INT modref_use_may_alias;
+ unsigned HOST_WIDE_INT modref_use_no_alias;
+ unsigned HOST_WIDE_INT modref_clobber_may_alias;
+ unsigned HOST_WIDE_INT modref_clobber_no_alias;
+ unsigned HOST_WIDE_INT modref_tests;
} alias_stats;
void
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);
+ fprintf (s, " nonoverlapping_component_refs_p: "
+ HOST_WIDE_INT_PRINT_DEC" disambiguations, "
+ HOST_WIDE_INT_PRINT_DEC" queries\n",
+ alias_stats.nonoverlapping_component_refs_p_no_alias,
+ alias_stats.nonoverlapping_component_refs_p_no_alias
+ + alias_stats.nonoverlapping_component_refs_p_may_alias);
+ fprintf (s, " nonoverlapping_refs_since_match_p: "
+ HOST_WIDE_INT_PRINT_DEC" disambiguations, "
+ HOST_WIDE_INT_PRINT_DEC" must overlaps, "
+ HOST_WIDE_INT_PRINT_DEC" queries\n",
+ alias_stats.nonoverlapping_refs_since_match_p_no_alias,
+ alias_stats.nonoverlapping_refs_since_match_p_must_overlap,
+ alias_stats.nonoverlapping_refs_since_match_p_no_alias
+ + alias_stats.nonoverlapping_refs_since_match_p_may_alias
+ + alias_stats.nonoverlapping_refs_since_match_p_must_overlap);
+ fprintf (s, " aliasing_component_refs_p: "
+ HOST_WIDE_INT_PRINT_DEC" disambiguations, "
+ HOST_WIDE_INT_PRINT_DEC" queries\n",
+ alias_stats.aliasing_component_refs_p_no_alias,
+ alias_stats.aliasing_component_refs_p_no_alias
+ + alias_stats.aliasing_component_refs_p_may_alias);
dump_alias_stats_in_alias_c (s);
+ fprintf (s, "\nModref stats:\n");
+ fprintf (s, " modref use: "
+ HOST_WIDE_INT_PRINT_DEC" disambiguations, "
+ HOST_WIDE_INT_PRINT_DEC" queries\n",
+ alias_stats.modref_use_no_alias,
+ alias_stats.modref_use_no_alias
+ + alias_stats.modref_use_may_alias);
+ fprintf (s, " modref clobber: "
+ HOST_WIDE_INT_PRINT_DEC" disambiguations, "
+ HOST_WIDE_INT_PRINT_DEC" queries\n "
+ HOST_WIDE_INT_PRINT_DEC" tbaa querries (%f per modref querry)\n",
+ alias_stats.modref_clobber_no_alias,
+ alias_stats.modref_clobber_no_alias
+ + alias_stats.modref_clobber_may_alias,
+ alias_stats.modref_tests,
+ ((double)alias_stats.modref_tests)
+ / (alias_stats.modref_clobber_no_alias
+ + alias_stats.modref_clobber_may_alias));
}
return true;
}
- /* Non-aliased variables can not be pointed to. */
+ /* Non-aliased variables cannot be pointed to. */
if (!may_be_aliased (decl))
return false;
{
if (ref->ref_alias_set != -1)
return ref->ref_alias_set;
+ if (!ref->ref)
+ return 0;
ref->ref_alias_set = get_alias_set (ref->ref);
return ref->ref_alias_set;
}
ref->volatile_p = false;
}
+/* S1 and S2 are TYPE_SIZE or DECL_SIZE. Compare them:
+ Return -1 if S1 < S2
+ Return 1 if S1 > S2
+ Return 0 if equal or incomparable. */
+
+static int
+compare_sizes (tree s1, tree s2)
+{
+ if (!s1 || !s2)
+ return 0;
+
+ poly_uint64 size1;
+ poly_uint64 size2;
+
+ if (!poly_int_tree_p (s1, &size1) || !poly_int_tree_p (s2, &size2))
+ return 0;
+ if (known_lt (size1, size2))
+ return -1;
+ if (known_lt (size2, size1))
+ return 1;
+ return 0;
+}
+
+/* Compare TYPE1 and TYPE2 by its size.
+ Return -1 if size of TYPE1 < size of TYPE2
+ Return 1 if size of TYPE1 > size of TYPE2
+ Return 0 if types are of equal sizes or we can not compare them. */
+
+static int
+compare_type_sizes (tree type1, tree type2)
+{
+ /* Be conservative for arrays and vectors. We want to support partial
+ overlap on int[3] and int[3] as tested in gcc.dg/torture/alias-2.c. */
+ while (TREE_CODE (type1) == ARRAY_TYPE
+ || TREE_CODE (type1) == VECTOR_TYPE)
+ type1 = TREE_TYPE (type1);
+ while (TREE_CODE (type2) == ARRAY_TYPE
+ || TREE_CODE (type2) == VECTOR_TYPE)
+ type2 = TREE_TYPE (type2);
+ return compare_sizes (TYPE_SIZE (type1), TYPE_SIZE (type2));
+}
+
/* 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. */
type1 = TYPE_MAIN_VARIANT (type1);
type2 = TYPE_MAIN_VARIANT (type2);
+ /* Handle the most common case first. */
+ if (type1 == type2)
+ return 1;
+
/* If we would have to do structural comparison bail out. */
if (TYPE_STRUCTURAL_EQUALITY_P (type1)
|| TYPE_STRUCTURAL_EQUALITY_P (type2))
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))
+ alias_set_type set1 = get_alias_set (type1);
+ alias_set_type set2 = get_alias_set (type2);
+ if (set1 == set2)
+ return -1;
+
+ /* Pointers to void are considered compatible with all other pointers,
+ so for two pointers see what the alias set resolution thinks. */
+ if (POINTER_TYPE_P (type1)
+ && POINTER_TYPE_P (type2)
+ && alias_sets_conflict_p (set1, set2))
return -1;
/* The types are known to be not equal. */
return 0;
}
+/* Return true if TYPE is a composite type (i.e. we may apply one of handled
+ components on it). */
+
+static bool
+type_has_components_p (tree type)
+{
+ return AGGREGATE_TYPE_P (type) || VECTOR_TYPE_P (type)
+ || TREE_CODE (type) == COMPLEX_TYPE;
+}
+
+/* MATCH1 and MATCH2 which are part of access path of REF1 and REF2
+ respectively are either pointing to same address or are completely
+ disjoint. If PARTIAL_OVERLAP is true, assume that outermost arrays may
+ just partly overlap.
+
+ Try to disambiguate using the access path starting from the match
+ and return false if there is no conflict.
+
+ Helper for aliasing_component_refs_p. */
+
+static bool
+aliasing_matching_component_refs_p (tree match1, tree ref1,
+ poly_int64 offset1, poly_int64 max_size1,
+ tree match2, tree ref2,
+ poly_int64 offset2, poly_int64 max_size2,
+ bool partial_overlap)
+{
+ poly_int64 offadj, sztmp, msztmp;
+ bool reverse;
+
+ if (!partial_overlap)
+ {
+ get_ref_base_and_extent (match2, &offadj, &sztmp, &msztmp, &reverse);
+ offset2 -= offadj;
+ get_ref_base_and_extent (match1, &offadj, &sztmp, &msztmp, &reverse);
+ offset1 -= offadj;
+ if (!ranges_maybe_overlap_p (offset1, max_size1, offset2, max_size2))
+ {
+ ++alias_stats.aliasing_component_refs_p_no_alias;
+ return false;
+ }
+ }
+
+ int cmp = nonoverlapping_refs_since_match_p (match1, ref1, match2, ref2,
+ partial_overlap);
+ if (cmp == 1
+ || (cmp == -1 && nonoverlapping_component_refs_p (ref1, ref2)))
+ {
+ ++alias_stats.aliasing_component_refs_p_no_alias;
+ return false;
+ }
+ ++alias_stats.aliasing_component_refs_p_may_alias;
+ return true;
+}
+
+/* Return true if REF is reference to zero sized trailing array. I.e.
+ struct foo {int bar; int array[0];} *fooptr;
+ fooptr->array. */
+
+static bool
+component_ref_to_zero_sized_trailing_array_p (tree ref)
+{
+ return (TREE_CODE (ref) == COMPONENT_REF
+ && TREE_CODE (TREE_TYPE (TREE_OPERAND (ref, 1))) == ARRAY_TYPE
+ && (!TYPE_SIZE (TREE_TYPE (TREE_OPERAND (ref, 1)))
+ || integer_zerop (TYPE_SIZE (TREE_TYPE (TREE_OPERAND (ref, 1)))))
+ && array_at_struct_end_p (ref));
+}
+
+/* Worker for aliasing_component_refs_p. Most parameters match parameters of
+ aliasing_component_refs_p.
+
+ Walk access path REF2 and try to find type matching TYPE1
+ (which is a start of possibly aliasing access path REF1).
+ If match is found, try to disambiguate.
+
+ Return 0 for sucessful disambiguation.
+ Return 1 if match was found but disambiguation failed
+ Return -1 if there is no match.
+ In this case MAYBE_MATCH is set to 0 if there is no type matching TYPE1
+ in access patch REF2 and -1 if we are not sure. */
+
+static int
+aliasing_component_refs_walk (tree ref1, tree type1, tree base1,
+ poly_int64 offset1, poly_int64 max_size1,
+ tree end_struct_ref1,
+ tree ref2, tree base2,
+ poly_int64 offset2, poly_int64 max_size2,
+ bool *maybe_match)
+{
+ tree ref = ref2;
+ int same_p = 0;
+
+ while (true)
+ {
+ /* We walk from inner type to the outer types. If type we see is
+ already too large to be part of type1, terminate the search. */
+ int cmp = compare_type_sizes (type1, TREE_TYPE (ref));
+
+ if (cmp < 0
+ && (!end_struct_ref1
+ || compare_type_sizes (TREE_TYPE (end_struct_ref1),
+ TREE_TYPE (ref)) < 0))
+ break;
+ /* If types may be of same size, see if we can decide about their
+ equality. */
+ if (cmp == 0)
+ {
+ same_p = same_type_for_tbaa (TREE_TYPE (ref), type1);
+ if (same_p == 1)
+ break;
+ /* In case we can't decide whether types are same try to
+ continue looking for the exact match.
+ Remember however that we possibly saw a match
+ to bypass the access path continuations tests we do later. */
+ if (same_p == -1)
+ *maybe_match = true;
+ }
+ if (!handled_component_p (ref))
+ break;
+ ref = TREE_OPERAND (ref, 0);
+ }
+ if (same_p == 1)
+ {
+ bool partial_overlap = false;
+
+ /* We assume that arrays can overlap by multiple of their elements
+ size as tested in gcc.dg/torture/alias-2.c.
+ This partial overlap happen only when both arrays are bases of
+ the access and not contained within another component ref.
+ To be safe we also assume partial overlap for VLAs. */
+ if (TREE_CODE (TREE_TYPE (base1)) == ARRAY_TYPE
+ && (!TYPE_SIZE (TREE_TYPE (base1))
+ || TREE_CODE (TYPE_SIZE (TREE_TYPE (base1))) != INTEGER_CST
+ || ref == base2))
+ {
+ /* Setting maybe_match to true triggers
+ nonoverlapping_component_refs_p test later that still may do
+ useful disambiguation. */
+ *maybe_match = true;
+ partial_overlap = true;
+ }
+ return aliasing_matching_component_refs_p (base1, ref1,
+ offset1, max_size1,
+ ref, ref2,
+ offset2, max_size2,
+ partial_overlap);
+ }
+ return -1;
+}
+
+/* Consider access path1 base1....ref1 and access path2 base2...ref2.
+ Return true if they can be composed to single access path
+ base1...ref1...base2...ref2.
+
+ REF_TYPE1 if type of REF1. END_STRUCT_PAST_END1 is true if there is
+ a trailing array access after REF1 in the non-TBAA part of the access.
+ REF1_ALIAS_SET is the alias set of REF1.
+
+ BASE_TYPE2 is type of base2. END_STRUCT_REF2 is non-NULL if there is
+ a traling array access in the TBAA part of access path2.
+ BASE2_ALIAS_SET is the alias set of base2. */
+
+bool
+access_path_may_continue_p (tree ref_type1, bool end_struct_past_end1,
+ alias_set_type ref1_alias_set,
+ tree base_type2, tree end_struct_ref2,
+ alias_set_type base2_alias_set)
+{
+ /* Access path can not continue past types with no components. */
+ if (!type_has_components_p (ref_type1))
+ return false;
+
+ /* If first access path ends by too small type to hold base of
+ the second access path, typically paths can not continue.
+
+ Punt if end_struct_past_end1 is true. We want to support arbitrary
+ type puning past first COMPONENT_REF to union because redundant store
+ elimination depends on this, see PR92152. For this reason we can not
+ check size of the reference because types may partially overlap. */
+ if (!end_struct_past_end1)
+ {
+ if (compare_type_sizes (ref_type1, base_type2) < 0)
+ return false;
+ /* If the path2 contains trailing array access we can strenghten the check
+ to verify that also the size of element of the trailing array fits.
+ In fact we could check for offset + type_size, but we do not track
+ offsets and this is quite side case. */
+ if (end_struct_ref2
+ && compare_type_sizes (ref_type1, TREE_TYPE (end_struct_ref2)) < 0)
+ return false;
+ }
+ return (base2_alias_set == ref1_alias_set
+ || alias_set_subset_of (base2_alias_set, ref1_alias_set));
+}
+
/* 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.
+ on an indirect reference may alias.
REF1_ALIAS_SET, BASE1_ALIAS_SET, REF2_ALIAS_SET and BASE2_ALIAS_SET
are the respective alias sets. */
tree ref2,
alias_set_type ref2_alias_set,
alias_set_type base2_alias_set,
- poly_int64 offset2, poly_int64 max_size2,
- bool ref2_is_decl)
+ poly_int64 offset2, poly_int64 max_size2)
{
/* If one reference is a component references through pointers try to find a
common base and apply offset based disambiguation. This handles
disambiguating q->i and p->a.j. */
tree base1, base2;
tree type1, type2;
- tree *refp;
- int same_p;
+ bool maybe_match = false;
+ tree end_struct_ref1 = NULL, end_struct_ref2 = NULL;
+ bool end_struct_past_end1 = false;
+ bool end_struct_past_end2 = false;
- /* Choose bases and base types to search for. */
+ /* Choose bases and base types to search for.
+ The access path is as follows:
+ base....end_of_tbaa_ref...actual_ref
+ At one place in the access path may be a reference to zero sized or
+ trailing array.
+
+ We generally discard the segment after end_of_tbaa_ref however
+ we need to be careful in case it contains zero sized or traling array.
+ These may happen after refernce to union and in this case we need to
+ not disambiguate type puning scenarios.
+
+ We set:
+ base1 to point to base
+
+ ref1 to point to end_of_tbaa_ref
+
+ end_struct_ref1 to point the trailing reference (if it exists
+ in range base....end_of_tbaa_ref
+
+ end_struct_past_end1 is true if this traling refernece occurs in
+ end_of_tbaa_ref...actual_ref. */
base1 = ref1;
while (handled_component_p (base1))
- base1 = TREE_OPERAND (base1, 0);
+ {
+ /* Generally access paths are monotous in the size of object. The
+ exception are trailing arrays of structures. I.e.
+ struct a {int array[0];};
+ or
+ struct a {int array1[0]; int array[];};
+ Such struct has size 0 but accesses to a.array may have non-zero size.
+ In this case the size of TREE_TYPE (base1) is smaller than
+ size of TREE_TYPE (TREE_OPERNAD (base1, 0)).
+
+ Because we compare sizes of arrays just by sizes of their elements,
+ we only need to care about zero sized array fields here. */
+ if (component_ref_to_zero_sized_trailing_array_p (base1))
+ {
+ gcc_checking_assert (!end_struct_ref1);
+ end_struct_ref1 = base1;
+ }
+ if (ends_tbaa_access_path_p (base1))
+ {
+ ref1 = TREE_OPERAND (base1, 0);
+ if (end_struct_ref1)
+ {
+ end_struct_past_end1 = true;
+ end_struct_ref1 = NULL;
+ }
+ }
+ base1 = TREE_OPERAND (base1, 0);
+ }
type1 = TREE_TYPE (base1);
base2 = ref2;
while (handled_component_p (base2))
- base2 = TREE_OPERAND (base2, 0);
+ {
+ if (component_ref_to_zero_sized_trailing_array_p (base2))
+ {
+ gcc_checking_assert (!end_struct_ref2);
+ end_struct_ref2 = base2;
+ }
+ if (ends_tbaa_access_path_p (base2))
+ {
+ ref2 = TREE_OPERAND (base2, 0);
+ if (end_struct_ref2)
+ {
+ end_struct_past_end2 = true;
+ end_struct_ref2 = NULL;
+ }
+ }
+ 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)
+ would be a common base for doing offset based disambiguation on.
+ This however only makes sense if type2 is big enough to hold type1. */
+ int cmp_outer = compare_type_sizes (type2, type1);
+
+ /* If type2 is big enough to contain type1 walk its access path.
+ We also need to care of arrays at the end of structs that may extend
+ beyond the end of structure. If this occurs in the TBAA part of the
+ access path, we need to consider the increased type as well. */
+ if (cmp_outer >= 0
+ || (end_struct_ref2
+ && compare_type_sizes (TREE_TYPE (end_struct_ref2), type1) >= 0))
{
- poly_int64 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_maybe_overlap_p (offset1, max_size1, offset2, max_size2);
+ int res = aliasing_component_refs_walk (ref1, type1, base1,
+ offset1, max_size1,
+ end_struct_ref1,
+ ref2, base2, offset2, max_size2,
+ &maybe_match);
+ if (res != -1)
+ return res;
}
+
/* 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)
+ if (cmp_outer <= 0
+ || (end_struct_ref1
+ && compare_type_sizes (TREE_TYPE (end_struct_ref1), type1) <= 0))
{
- poly_int64 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_maybe_overlap_p (offset1, max_size1, offset2, max_size2);
+ int res = aliasing_component_refs_walk (ref2, type2, base2,
+ offset2, max_size2,
+ end_struct_ref2,
+ ref1, base1, offset1, max_size1,
+ &maybe_match);
+ if (res != -1)
+ return res;
}
- /* 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));
+ /* In the following code we make an assumption that the types in access
+ paths do not overlap and thus accesses alias only if one path can be
+ continuation of another. If we was not able to decide about equivalence,
+ we need to give up. */
+ if (maybe_match)
+ {
+ if (!nonoverlapping_component_refs_p (ref1, ref2))
+ {
+ ++alias_stats.aliasing_component_refs_p_may_alias;
+ return true;
+ }
+ ++alias_stats.aliasing_component_refs_p_no_alias;
+ return false;
+ }
+
+ if (access_path_may_continue_p (TREE_TYPE (ref1), end_struct_past_end1,
+ ref1_alias_set,
+ type2, end_struct_ref2,
+ base2_alias_set)
+ || access_path_may_continue_p (TREE_TYPE (ref2), end_struct_past_end2,
+ ref2_alias_set,
+ type1, end_struct_ref1,
+ base1_alias_set))
+ {
+ ++alias_stats.aliasing_component_refs_p_may_alias;
+ return true;
+ }
+ ++alias_stats.aliasing_component_refs_p_no_alias;
return false;
}
-/* Return true if we can determine that component references REF1 and REF2,
- that are within a common DECL, cannot overlap. */
+/* FIELD1 and FIELD2 are two fields of component refs. We assume
+ that bases of both component refs are either equivalent or nonoverlapping.
+ We do not assume that the containers of FIELD1 and FIELD2 are of the
+ same type or size.
-static bool
-nonoverlapping_component_refs_of_decl_p (tree ref1, tree ref2)
+ Return 0 in case the base address of component_refs are same then
+ FIELD1 and FIELD2 have same address. Note that FIELD1 and FIELD2
+ may not be of same type or size.
+
+ Return 1 if FIELD1 and FIELD2 are non-overlapping.
+
+ Return -1 otherwise.
+
+ Main difference between 0 and -1 is to let
+ nonoverlapping_component_refs_since_match_p discover the semantically
+ equivalent part of the access path.
+
+ Note that this function is used even with -fno-strict-aliasing
+ and makes use of no TBAA assumptions. */
+
+static int
+nonoverlapping_component_refs_p_1 (const_tree field1, const_tree field2)
+{
+ /* If both fields are of the same type, we could save hard work of
+ comparing offsets. */
+ tree type1 = DECL_CONTEXT (field1);
+ tree type2 = DECL_CONTEXT (field2);
+
+ if (TREE_CODE (type1) == RECORD_TYPE
+ && DECL_BIT_FIELD_REPRESENTATIVE (field1))
+ field1 = DECL_BIT_FIELD_REPRESENTATIVE (field1);
+ if (TREE_CODE (type2) == RECORD_TYPE
+ && DECL_BIT_FIELD_REPRESENTATIVE (field2))
+ field2 = DECL_BIT_FIELD_REPRESENTATIVE (field2);
+
+ /* ??? Bitfields can overlap at RTL level so punt on them.
+ FIXME: RTL expansion should be fixed by adjusting the access path
+ when producing MEM_ATTRs for MEMs which are wider than
+ the bitfields similarly as done in set_mem_attrs_minus_bitpos. */
+ if (DECL_BIT_FIELD (field1) && DECL_BIT_FIELD (field2))
+ return -1;
+
+ /* Assume that different FIELD_DECLs never overlap within a RECORD_TYPE. */
+ if (type1 == type2 && TREE_CODE (type1) == RECORD_TYPE)
+ return field1 != field2;
+
+ /* In common case the offsets and bit offsets will be the same.
+ However if frontends do not agree on the alignment, they may be
+ different even if they actually represent same address.
+ Try the common case first and if that fails calcualte the
+ actual bit offset. */
+ if (tree_int_cst_equal (DECL_FIELD_OFFSET (field1),
+ DECL_FIELD_OFFSET (field2))
+ && tree_int_cst_equal (DECL_FIELD_BIT_OFFSET (field1),
+ DECL_FIELD_BIT_OFFSET (field2)))
+ return 0;
+
+ /* Note that it may be possible to use component_ref_field_offset
+ which would provide offsets as trees. However constructing and folding
+ trees is expensive and does not seem to be worth the compile time
+ cost. */
+
+ poly_uint64 offset1, offset2;
+ poly_uint64 bit_offset1, bit_offset2;
+
+ if (poly_int_tree_p (DECL_FIELD_OFFSET (field1), &offset1)
+ && poly_int_tree_p (DECL_FIELD_OFFSET (field2), &offset2)
+ && poly_int_tree_p (DECL_FIELD_BIT_OFFSET (field1), &bit_offset1)
+ && poly_int_tree_p (DECL_FIELD_BIT_OFFSET (field2), &bit_offset2))
+ {
+ offset1 = (offset1 << LOG2_BITS_PER_UNIT) + bit_offset1;
+ offset2 = (offset2 << LOG2_BITS_PER_UNIT) + bit_offset2;
+
+ if (known_eq (offset1, offset2))
+ return 0;
+
+ poly_uint64 size1, size2;
+
+ if (poly_int_tree_p (DECL_SIZE (field1), &size1)
+ && poly_int_tree_p (DECL_SIZE (field2), &size2)
+ && !ranges_maybe_overlap_p (offset1, size1, offset2, size2))
+ return 1;
+ }
+ /* Resort to slower overlap checking by looking for matching types in
+ the middle of access path. */
+ return -1;
+}
+
+/* Return low bound of array. Do not produce new trees
+ and thus do not care about particular type of integer constant
+ and placeholder exprs. */
+
+static tree
+cheap_array_ref_low_bound (tree ref)
{
+ tree domain_type = TYPE_DOMAIN (TREE_TYPE (TREE_OPERAND (ref, 0)));
+
+ /* Avoid expensive array_ref_low_bound.
+ low bound is either stored in operand2, or it is TYPE_MIN_VALUE of domain
+ type or it is zero. */
+ if (TREE_OPERAND (ref, 2))
+ return TREE_OPERAND (ref, 2);
+ else if (domain_type && TYPE_MIN_VALUE (domain_type))
+ return TYPE_MIN_VALUE (domain_type);
+ else
+ return integer_zero_node;
+}
+
+/* REF1 and REF2 are ARRAY_REFs with either same base address or which are
+ completely disjoint.
+
+ Return 1 if the refs are non-overlapping.
+ Return 0 if they are possibly overlapping but if so the overlap again
+ starts on the same address.
+ Return -1 otherwise. */
+
+int
+nonoverlapping_array_refs_p (tree ref1, tree ref2)
+{
+ tree index1 = TREE_OPERAND (ref1, 1);
+ tree index2 = TREE_OPERAND (ref2, 1);
+ tree low_bound1 = cheap_array_ref_low_bound (ref1);
+ tree low_bound2 = cheap_array_ref_low_bound (ref2);
+
+ /* Handle zero offsets first: we do not need to match type size in this
+ case. */
+ if (operand_equal_p (index1, low_bound1, 0)
+ && operand_equal_p (index2, low_bound2, 0))
+ return 0;
+
+ /* If type sizes are different, give up.
+
+ Avoid expensive array_ref_element_size.
+ If operand 3 is present it denotes size in the alignmnet units.
+ Otherwise size is TYPE_SIZE of the element type.
+ Handle only common cases where types are of the same "kind". */
+ if ((TREE_OPERAND (ref1, 3) == NULL) != (TREE_OPERAND (ref2, 3) == NULL))
+ return -1;
+
+ tree elmt_type1 = TREE_TYPE (TREE_TYPE (TREE_OPERAND (ref1, 0)));
+ tree elmt_type2 = TREE_TYPE (TREE_TYPE (TREE_OPERAND (ref2, 0)));
+
+ if (TREE_OPERAND (ref1, 3))
+ {
+ if (TYPE_ALIGN (elmt_type1) != TYPE_ALIGN (elmt_type2)
+ || !operand_equal_p (TREE_OPERAND (ref1, 3),
+ TREE_OPERAND (ref2, 3), 0))
+ return -1;
+ }
+ else
+ {
+ if (!operand_equal_p (TYPE_SIZE_UNIT (elmt_type1),
+ TYPE_SIZE_UNIT (elmt_type2), 0))
+ return -1;
+ }
+
+ /* Since we know that type sizes are the same, there is no need to return
+ -1 after this point. Partial overlap can not be introduced. */
+
+ /* We may need to fold trees in this case.
+ TODO: Handle integer constant case at least. */
+ if (!operand_equal_p (low_bound1, low_bound2, 0))
+ return 0;
+
+ if (TREE_CODE (index1) == INTEGER_CST && TREE_CODE (index2) == INTEGER_CST)
+ {
+ if (tree_int_cst_equal (index1, index2))
+ return 0;
+ return 1;
+ }
+ /* TODO: We can use VRP to further disambiguate here. */
+ return 0;
+}
+
+/* Try to disambiguate REF1 and REF2 under the assumption that MATCH1 and
+ MATCH2 either point to the same address or are disjoint.
+ MATCH1 and MATCH2 are assumed to be ref in the access path of REF1 and REF2
+ respectively or NULL in the case we established equivalence of bases.
+ If PARTIAL_OVERLAP is true assume that the toplevel arrays may actually
+ overlap by exact multiply of their element size.
+
+ This test works by matching the initial segment of the access path
+ and does not rely on TBAA thus is safe for !flag_strict_aliasing if
+ match was determined without use of TBAA oracle.
+
+ Return 1 if we can determine that component references REF1 and REF2,
+ that are within a common DECL, cannot overlap.
+
+ Return 0 if paths are same and thus there is nothing to disambiguate more
+ (i.e. there is must alias assuming there is must alias between MATCH1 and
+ MATCH2)
+
+ Return -1 if we can not determine 0 or 1 - this happens when we met
+ non-matching types was met in the path.
+ In this case it may make sense to continue by other disambiguation
+ oracles. */
+
+static int
+nonoverlapping_refs_since_match_p (tree match1, tree ref1,
+ tree match2, tree ref2,
+ bool partial_overlap)
+{
+ int ntbaa1 = 0, ntbaa2 = 0;
+ /* Early return if there are no references to match, we do not need
+ to walk the access paths.
+
+ Do not consider this as may-alias for stats - it is more useful
+ to have information how many disambiguations happened provided that
+ the query was meaningful. */
+
+ if (match1 == ref1 || !handled_component_p (ref1)
+ || match2 == ref2 || !handled_component_p (ref2))
+ return -1;
+
auto_vec<tree, 16> component_refs1;
auto_vec<tree, 16> component_refs2;
/* Create the stack of handled components for REF1. */
- while (handled_component_p (ref1))
+ while (handled_component_p (ref1) && ref1 != match1)
{
+ /* We use TBAA only to re-synchronize after mismatched refs. So we
+ do not need to truncate access path after TBAA part ends. */
+ if (ends_tbaa_access_path_p (ref1))
+ ntbaa1 = 0;
+ else
+ ntbaa1++;
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))
+ while (handled_component_p (ref2) && ref2 != match2)
{
+ if (ends_tbaa_access_path_p (ref2))
+ ntbaa2 = 0;
+ else
+ ntbaa2++;
component_refs2.safe_push (ref2);
ref2 = TREE_OPERAND (ref2, 0);
}
- if (TREE_CODE (ref2) == MEM_REF)
+
+ if (!flag_strict_aliasing)
{
- if (!integer_zerop (TREE_OPERAND (ref2, 1)))
- return false;
- ref2 = TREE_OPERAND (TREE_OPERAND (ref2, 0), 0);
+ ntbaa1 = 0;
+ ntbaa2 = 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));
+ bool mem_ref1 = TREE_CODE (ref1) == MEM_REF && ref1 != match1;
+ bool mem_ref2 = TREE_CODE (ref2) == MEM_REF && ref2 != match2;
+
+ /* If only one of access path starts with MEM_REF check that offset is 0
+ so the addresses stays the same after stripping it.
+ TODO: In this case we may walk the other access path until we get same
+ offset.
+
+ If both starts with MEM_REF, offset has to be same. */
+ if ((mem_ref1 && !mem_ref2 && !integer_zerop (TREE_OPERAND (ref1, 1)))
+ || (mem_ref2 && !mem_ref1 && !integer_zerop (TREE_OPERAND (ref2, 1)))
+ || (mem_ref1 && mem_ref2
+ && !tree_int_cst_equal (TREE_OPERAND (ref1, 1),
+ TREE_OPERAND (ref2, 1))))
+ {
+ ++alias_stats.nonoverlapping_refs_since_match_p_may_alias;
+ return -1;
+ }
+
+ /* TARGET_MEM_REF are never wrapped in handled components, so we do not need
+ to handle them here at all. */
+ gcc_checking_assert (TREE_CODE (ref1) != TARGET_MEM_REF
+ && TREE_CODE (ref2) != TARGET_MEM_REF);
/* 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
case the return value will precisely be false. */
while (true)
{
+ /* Track if we seen unmatched ref with non-zero offset. In this case
+ we must look for partial overlaps. */
+ bool seen_unmatched_ref_p = false;
+
+ /* First match ARRAY_REFs an try to disambiguate. */
+ if (!component_refs1.is_empty ()
+ && !component_refs2.is_empty ())
+ {
+ unsigned int narray_refs1=0, narray_refs2=0;
+
+ /* We generally assume that both access paths starts by same sequence
+ of refs. However if number of array refs is not in sync, try
+ to recover and pop elts until number match. This helps the case
+ where one access path starts by array and other by element. */
+ for (narray_refs1 = 0; narray_refs1 < component_refs1.length ();
+ narray_refs1++)
+ if (TREE_CODE (component_refs1 [component_refs1.length()
+ - 1 - narray_refs1]) != ARRAY_REF)
+ break;
+
+ for (narray_refs2 = 0; narray_refs2 < component_refs2.length ();
+ narray_refs2++)
+ if (TREE_CODE (component_refs2 [component_refs2.length()
+ - 1 - narray_refs2]) != ARRAY_REF)
+ break;
+ for (; narray_refs1 > narray_refs2; narray_refs1--)
+ {
+ ref1 = component_refs1.pop ();
+ ntbaa1--;
+
+ /* If index is non-zero we need to check whether the reference
+ does not break the main invariant that bases are either
+ disjoint or equal. Consider the example:
+
+ unsigned char out[][1];
+ out[1]="a";
+ out[i][0];
+
+ Here bases out and out are same, but after removing the
+ [i] index, this invariant no longer holds, because
+ out[i] points to the middle of array out.
+
+ TODO: If size of type of the skipped reference is an integer
+ multiply of the size of type of the other reference this
+ invariant can be verified, but even then it is not completely
+ safe with !flag_strict_aliasing if the other reference contains
+ unbounded array accesses.
+ See */
+
+ if (!operand_equal_p (TREE_OPERAND (ref1, 1),
+ cheap_array_ref_low_bound (ref1), 0))
+ return 0;
+ }
+ for (; narray_refs2 > narray_refs1; narray_refs2--)
+ {
+ ref2 = component_refs2.pop ();
+ ntbaa2--;
+ if (!operand_equal_p (TREE_OPERAND (ref2, 1),
+ cheap_array_ref_low_bound (ref2), 0))
+ return 0;
+ }
+ /* Try to disambiguate matched arrays. */
+ for (unsigned int i = 0; i < narray_refs1; i++)
+ {
+ int cmp = nonoverlapping_array_refs_p (component_refs1.pop (),
+ component_refs2.pop ());
+ ntbaa1--;
+ ntbaa2--;
+ if (cmp == 1 && !partial_overlap)
+ {
+ ++alias_stats
+ .nonoverlapping_refs_since_match_p_no_alias;
+ return 1;
+ }
+ if (cmp == -1)
+ {
+ seen_unmatched_ref_p = true;
+ /* We can not maintain the invariant that bases are either
+ same or completely disjoint. However we can still recover
+ from type based alias analysis if we reach referneces to
+ same sizes. We do not attempt to match array sizes, so
+ just finish array walking and look for component refs. */
+ if (ntbaa1 < 0 || ntbaa2 < 0)
+ {
+ ++alias_stats.nonoverlapping_refs_since_match_p_may_alias;
+ return -1;
+ }
+ for (i++; i < narray_refs1; i++)
+ {
+ component_refs1.pop ();
+ component_refs2.pop ();
+ ntbaa1--;
+ ntbaa2--;
+ }
+ break;
+ }
+ partial_overlap = false;
+ }
+ }
+
+ /* Next look for component_refs. */
do
{
if (component_refs1.is_empty ())
- return false;
+ {
+ ++alias_stats
+ .nonoverlapping_refs_since_match_p_must_overlap;
+ return 0;
+ }
ref1 = component_refs1.pop ();
+ ntbaa1--;
+ if (TREE_CODE (ref1) != COMPONENT_REF)
+ {
+ seen_unmatched_ref_p = true;
+ if (ntbaa1 < 0 || ntbaa2 < 0)
+ {
+ ++alias_stats.nonoverlapping_refs_since_match_p_may_alias;
+ return -1;
+ }
+ }
}
while (!RECORD_OR_UNION_TYPE_P (TREE_TYPE (TREE_OPERAND (ref1, 0))));
do
{
if (component_refs2.is_empty ())
- return false;
+ {
+ ++alias_stats
+ .nonoverlapping_refs_since_match_p_must_overlap;
+ return 0;
+ }
ref2 = component_refs2.pop ();
+ ntbaa2--;
+ if (TREE_CODE (ref2) != COMPONENT_REF)
+ {
+ if (ntbaa1 < 0 || ntbaa2 < 0)
+ {
+ ++alias_stats.nonoverlapping_refs_since_match_p_may_alias;
+ return -1;
+ }
+ seen_unmatched_ref_p = true;
+ }
}
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;
+ /* BIT_FIELD_REF and VIEW_CONVERT_EXPR are taken off the vectors
+ earlier. */
+ gcc_checking_assert (TREE_CODE (ref1) == COMPONENT_REF
+ && TREE_CODE (ref2) == COMPONENT_REF);
tree field1 = TREE_OPERAND (ref1, 1);
tree field2 = TREE_OPERAND (ref2, 1);
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;
+ partial_overlap = false;
- if (field1 != field2)
+ /* If we skipped array refs on type of different sizes, we can
+ no longer be sure that there are not partial overlaps. */
+ if (seen_unmatched_ref_p && ntbaa1 >= 0 && ntbaa2 >= 0
+ && !operand_equal_p (TYPE_SIZE (type1), TYPE_SIZE (type2), 0))
{
- /* 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;
+ ++alias_stats
+ .nonoverlapping_refs_since_match_p_may_alias;
+ return -1;
+ }
+
+ int cmp = nonoverlapping_component_refs_p_1 (field1, field2);
+ if (cmp == -1)
+ {
+ ++alias_stats
+ .nonoverlapping_refs_since_match_p_may_alias;
+ return -1;
+ }
+ else if (cmp == 1)
+ {
+ ++alias_stats
+ .nonoverlapping_refs_since_match_p_no_alias;
+ return 1;
}
}
- return false;
+ ++alias_stats.nonoverlapping_refs_since_match_p_must_overlap;
+ return 0;
+}
+
+/* Return TYPE_UID which can be used to match record types we consider
+ same for TBAA purposes. */
+
+static inline int
+ncr_type_uid (const_tree field)
+{
+ /* ??? 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 type = DECL_FIELD_CONTEXT (field);
+ /* With LTO types considered same_type_for_tbaa_p
+ from different translation unit may not have same
+ main variant. They however have same TYPE_CANONICAL. */
+ if (TYPE_CANONICAL (type))
+ return TYPE_UID (TYPE_CANONICAL (type));
+ return TYPE_UID (type);
}
/* qsort compare function to sort FIELD_DECLs after their
{
const_tree field1 = *(const_tree *) const_cast <void *>(field1_);
const_tree field2 = *(const_tree *) const_cast <void *>(field2_);
- unsigned int uid1 = TYPE_UID (DECL_FIELD_CONTEXT (field1));
- unsigned int uid2 = TYPE_UID (DECL_FIELD_CONTEXT (field2));
+ unsigned int uid1 = ncr_type_uid (field1);
+ unsigned int uid2 = ncr_type_uid (field2);
+
if (uid1 < uid2)
return -1;
else if (uid1 > uid2)
}
/* Return true if we can determine that the fields referenced cannot
- overlap for any pair of objects. */
+ overlap for any pair of objects. This relies on TBAA. */
static bool
nonoverlapping_component_refs_p (const_tree x, const_tree y)
{
+ /* Early return if we have nothing to do.
+
+ Do not consider this as may-alias for stats - it is more useful
+ to have information how many disambiguations happened provided that
+ the query was meaningful. */
if (!flag_strict_aliasing
|| !x || !y
- || TREE_CODE (x) != COMPONENT_REF
- || TREE_CODE (y) != COMPONENT_REF)
+ || !handled_component_p (x)
+ || !handled_component_p (y))
return false;
auto_vec<const_tree, 16> fieldsx;
- while (TREE_CODE (x) == COMPONENT_REF)
+ while (handled_component_p (x))
{
- tree field = TREE_OPERAND (x, 1);
- tree type = DECL_FIELD_CONTEXT (field);
- if (TREE_CODE (type) == RECORD_TYPE)
- fieldsx.safe_push (field);
+ if (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);
+ }
+ else if (ends_tbaa_access_path_p (x))
+ fieldsx.truncate (0);
x = TREE_OPERAND (x, 0);
}
if (fieldsx.length () == 0)
return false;
auto_vec<const_tree, 16> fieldsy;
- while (TREE_CODE (y) == COMPONENT_REF)
+ while (handled_component_p (y))
{
- 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));
+ if (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));
+ }
+ else if (ends_tbaa_access_path_p (y))
+ fieldsy.truncate (0);
y = TREE_OPERAND (y, 0);
}
if (fieldsy.length () == 0)
- return false;
+ {
+ ++alias_stats.nonoverlapping_component_refs_p_may_alias;
+ 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 (same_type_for_tbaa (DECL_FIELD_CONTEXT (fieldsx[0]),
+ DECL_FIELD_CONTEXT (fieldsy[0])) == 1
+ && nonoverlapping_component_refs_p_1 (fieldsx[0], fieldsy[0]) == 1)
+ {
+ ++alias_stats.nonoverlapping_component_refs_p_no_alias;
+ return true;
+ }
+ else
+ {
+ ++alias_stats.nonoverlapping_component_refs_p_may_alias;
+ return false;
+ }
+ }
if (fieldsx.length () == 2)
{
{
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 (same_type_for_tbaa (DECL_FIELD_CONTEXT (fieldx),
+ DECL_FIELD_CONTEXT (fieldy)) == 1
+ && nonoverlapping_component_refs_p_1 (fieldx, fieldy) == 1)
{
- /* 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;
- }
+ ++alias_stats.nonoverlapping_component_refs_p_no_alias;
+ return true;
}
- if (TYPE_UID (typex) < TYPE_UID (typey))
+
+ if (ncr_type_uid (fieldx) < ncr_type_uid (fieldy))
{
i++;
if (i == fieldsx.length ())
}
while (1);
+ ++alias_stats.nonoverlapping_component_refs_p_may_alias;
return false;
}
static bool
decl_refs_may_alias_p (tree ref1, tree base1,
poly_int64 offset1, poly_int64 max_size1,
+ poly_int64 size1,
tree ref2, tree base2,
- poly_int64 offset2, poly_int64 max_size2)
+ poly_int64 offset2, poly_int64 max_size2,
+ poly_int64 size2)
{
gcc_checking_assert (DECL_P (base1) && DECL_P (base2));
if (!ranges_maybe_overlap_p (offset1, max_size1, offset2, max_size2))
return false;
+ /* If there is must alias, there is no use disambiguating further. */
+ if (known_eq (size1, max_size1) && known_eq (size2, max_size2))
+ return true;
+
/* 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))
+ && nonoverlapping_refs_since_match_p (NULL, ref1, NULL, ref2, false) == 1)
return false;
return true;
static bool
indirect_ref_may_alias_decl_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
poly_int64 offset1, poly_int64 max_size1,
+ poly_int64 size1,
alias_set_type ref1_alias_set,
alias_set_type base1_alias_set,
tree ref2 ATTRIBUTE_UNUSED, tree base2,
poly_int64 offset2, poly_int64 max_size2,
+ poly_int64 size2,
alias_set_type ref2_alias_set,
alias_set_type base2_alias_set, bool tbaa_p)
{
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)
+ if (base1_alias_set == 0 || base2_alias_set == 0)
return true;
/* When we are trying to disambiguate an access with a pointer dereference
if (base1_alias_set != base2_alias_set
&& !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
return false;
+
+ ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
+
/* 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))
- && poly_int_tree_p (DECL_SIZE (base2))
- && poly_int_tree_p (TYPE_SIZE (TREE_TYPE (ptrtype1)))
- /* ??? This in turn may run afoul when a decl of type T which is
+ if (/* ??? 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)) != UNION_TYPE
&& TREE_CODE (TREE_TYPE (ptrtype1)) != QUAL_UNION_TYPE
- && known_lt (wi::to_poly_widest (DECL_SIZE (base2)),
- wi::to_poly_widest (TYPE_SIZE (TREE_TYPE (ptrtype1)))))
+ && compare_sizes (DECL_SIZE (base2),
+ TYPE_SIZE (TREE_TYPE (ptrtype1))) < 0)
return false;
if (!ref2)
poly_offset_int doffset2 = offset2;
if (TREE_CODE (dbase2) == MEM_REF
|| TREE_CODE (dbase2) == TARGET_MEM_REF)
- doffset2 -= mem_ref_offset (dbase2) << LOG2_BITS_PER_UNIT;
+ {
+ doffset2 -= mem_ref_offset (dbase2) << LOG2_BITS_PER_UNIT;
+ tree ptrtype2 = TREE_TYPE (TREE_OPERAND (dbase2, 1));
+ /* If second reference is view-converted, give up now. */
+ if (same_type_for_tbaa (TREE_TYPE (dbase2), TREE_TYPE (ptrtype2)) != 1)
+ return true;
+ }
- /* 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)
+ /* If first reference is view-converted, give up now. */
+ if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1)
return true;
/* If both references are through the same type, they do not alias
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
+ pointer offset.
+
+ But avoid treating variable length arrays as "objects", instead assume they
+ can overlap by an exact multiple of their element size.
+ See gcc.dg/torture/alias-2.c. */
+ if (((TREE_CODE (base1) != TARGET_MEM_REF
|| (!TMR_INDEX (base1) && !TMR_INDEX2 (base1)))
+ && (TREE_CODE (dbase2) != TARGET_MEM_REF
+ || (!TMR_INDEX (dbase2) && !TMR_INDEX2 (dbase2))))
&& same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (dbase2)) == 1)
- return ranges_maybe_overlap_p (doffset1, max_size1, doffset2, max_size2);
-
- if (ref1 && ref2
- && nonoverlapping_component_refs_p (ref1, ref2))
- return false;
+ {
+ bool partial_overlap = (TREE_CODE (TREE_TYPE (base1)) == ARRAY_TYPE
+ && (TYPE_SIZE (TREE_TYPE (base1))
+ && TREE_CODE (TYPE_SIZE (TREE_TYPE (base1)))
+ != INTEGER_CST));
+ if (!partial_overlap
+ && !ranges_maybe_overlap_p (doffset1, max_size1, doffset2, max_size2))
+ return false;
+ if (!ref1 || !ref2
+ /* If there is must alias, there is no use disambiguating further. */
+ || (!partial_overlap
+ && known_eq (size1, max_size1) && known_eq (size2, max_size2)))
+ return true;
+ int res = nonoverlapping_refs_since_match_p (base1, ref1, base2, ref2,
+ partial_overlap);
+ if (res == -1)
+ return !nonoverlapping_component_refs_p (ref1, ref2);
+ return !res;
+ }
/* Do access-path based disambiguation. */
if (ref1 && ref2
offset1, max_size1,
ref2,
ref2_alias_set, base2_alias_set,
- offset2, max_size2, true);
+ offset2, max_size2);
return true;
}
static bool
indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED, tree base1,
poly_int64 offset1, poly_int64 max_size1,
+ poly_int64 size1,
alias_set_type ref1_alias_set,
alias_set_type base1_alias_set,
tree ref2 ATTRIBUTE_UNUSED, tree base2,
poly_int64 offset2, poly_int64 max_size2,
+ poly_int64 size2,
alias_set_type ref2_alias_set,
alias_set_type base2_alias_set, bool tbaa_p)
{
{
poly_offset_int moff1 = mem_ref_offset (base1) << LOG2_BITS_PER_UNIT;
poly_offset_int moff2 = mem_ref_offset (base2) << LOG2_BITS_PER_UNIT;
- return ranges_maybe_overlap_p (offset1 + moff1, max_size1,
- offset2 + moff2, max_size2);
+ if (!ranges_maybe_overlap_p (offset1 + moff1, max_size1,
+ offset2 + moff2, max_size2))
+ return false;
+ /* If there is must alias, there is no use disambiguating further. */
+ if (known_eq (size1, max_size1) && known_eq (size2, max_size2))
+ return true;
+ if (ref1 && ref2)
+ {
+ int res = nonoverlapping_refs_since_match_p (NULL, ref1, NULL, ref2,
+ false);
+ if (res != -1)
+ return !res;
+ }
}
if (!ptr_derefs_may_alias_p (ptr1, ptr2))
return false;
|| 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_maybe_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))
|| same_type_for_tbaa (TREE_TYPE (base2), TREE_TYPE (ptrtype2)) != 1)
return true;
- if (ref1 && ref2
- && nonoverlapping_component_refs_p (ref1, ref2))
- return false;
+ /* If both references are through the same type, they do not alias
+ if the accesses do not overlap. This does extra disambiguation
+ for mixed/pointer accesses but requires strict aliasing. */
+ if ((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 (ptrtype1),
+ TREE_TYPE (ptrtype2)) == 1)
+ {
+ /* But avoid treating arrays as "objects", instead assume they
+ can overlap by an exact multiple of their element size.
+ See gcc.dg/torture/alias-2.c. */
+ bool partial_overlap = TREE_CODE (TREE_TYPE (ptrtype1)) == ARRAY_TYPE;
+
+ if (!partial_overlap
+ && !ranges_maybe_overlap_p (offset1, max_size1, offset2, max_size2))
+ return false;
+ if (!ref1 || !ref2
+ || (!partial_overlap
+ && known_eq (size1, max_size1) && known_eq (size2, max_size2)))
+ return true;
+ int res = nonoverlapping_refs_since_match_p (base1, ref1, base2, ref2,
+ partial_overlap);
+ if (res == -1)
+ return !nonoverlapping_component_refs_p (ref1, ref2);
+ return !res;
+ }
/* Do access-path based disambiguation. */
if (ref1 && ref2
offset1, max_size1,
ref2,
ref2_alias_set, base2_alias_set,
- offset2, max_size2, false);
+ offset2, max_size2);
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)
+static bool
+refs_may_alias_p_2 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
{
tree base1, base2;
poly_int64 offset1 = 0, offset2 = 0;
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);
+ ref1->size,
+ ref2->ref, base2, offset2, max_size2,
+ ref2->size);
/* Handle restrict based accesses.
??? ao_ref_base strips inner MEM_REF [&decl], recover from that
/* 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,
+ offset2, max_size2, ref2->size,
ao_ref_alias_set (ref2),
ao_ref_base_alias_set (ref2),
ref1->ref, base1,
- offset1, max_size1,
+ offset1, max_size1, ref1->size,
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,
+ offset1, max_size1, ref1->size,
ao_ref_alias_set (ref1),
ao_ref_base_alias_set (ref1),
ref2->ref, base2,
- offset2, max_size2,
+ offset2, max_size2, ref2->size,
ao_ref_alias_set (ref2),
ao_ref_base_alias_set (ref2),
tbaa_p);
gcc_unreachable ();
}
+/* Return true, if the two memory references REF1 and REF2 may alias
+ and update statistics. */
+
+bool
+refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
+{
+ bool res = refs_may_alias_p_2 (ref1, ref2, tbaa_p);
+ if (res)
+ ++alias_stats.refs_may_alias_p_may_alias;
+ else
+ ++alias_stats.refs_may_alias_p_no_alias;
+ return res;
+}
+
static bool
refs_may_alias_p (tree ref1, ao_ref *ref2, bool tbaa_p)
{
refs_may_alias_p (tree ref1, tree ref2, bool tbaa_p)
{
ao_ref r1, r2;
- bool res;
ao_ref_init (&r1, ref1);
ao_ref_init (&r2, ref2);
- res = refs_may_alias_p_1 (&r1, &r2, tbaa_p);
- if (res)
- ++alias_stats.refs_may_alias_p_may_alias;
- else
- ++alias_stats.refs_may_alias_p_no_alias;
- return res;
+ return refs_may_alias_p_1 (&r1, &r2, tbaa_p);
}
/* Returns true if there is a anti-dependence for the STORE that
return refs_may_alias_p_1 (&r1, &r2, false);
}
+/* Returns true if and only if REF may alias any access stored in TT.
+ IF TBAA_P is true, use TBAA oracle. */
+
+static bool
+modref_may_conflict (modref_tree <alias_set_type> *tt, ao_ref *ref, bool tbaa_p)
+{
+ alias_set_type base_set, ref_set;
+ modref_base_node <alias_set_type> *base_node;
+ modref_ref_node <alias_set_type> *ref_node;
+ size_t i, j;
+
+ if (tt->every_base)
+ return true;
+
+ base_set = ao_ref_base_alias_set (ref);
+
+ ref_set = ao_ref_alias_set (ref);
+
+ int num_tests = 0, max_tests = param_modref_max_tests;
+ FOR_EACH_VEC_SAFE_ELT (tt->bases, i, base_node)
+ {
+ if (base_node->every_ref)
+ return true;
+
+ if (!base_node->base)
+ return true;
+
+ if (tbaa_p && flag_strict_aliasing)
+ {
+ if (!alias_sets_conflict_p (base_set, base_node->base))
+ continue;
+ alias_stats.modref_tests++;
+ num_tests++;
+ }
+ else
+ return true;
+ if (num_tests >= max_tests)
+ return true;
+
+ FOR_EACH_VEC_SAFE_ELT (base_node->refs, j, ref_node)
+ {
+ /* Do not repeat same test as before. */
+ if (ref_set == base_set && base_node->base == ref_node->ref)
+ return true;
+ if (!flag_strict_aliasing)
+ return true;
+ if (alias_sets_conflict_p (ref_set, ref_node->ref))
+ return true;
+ alias_stats.modref_tests++;
+ num_tests++;
+ if (num_tests >= max_tests)
+ return true;
+ }
+ }
+ return false;
+}
+
/* If the call CALL may use the memory reference REF return true,
otherwise return false. */
&& (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;
+ callee = gimple_call_fndecl (call);
+
+ if (!gimple_call_chain (call) && callee != NULL_TREE)
+ {
+ struct cgraph_node *node = cgraph_node::get (callee);
+ /* We can not safely optimize based on summary of calle if it does
+ not always bind to current def: it is possible that memory load
+ was optimized out earlier and the interposed variant may not be
+ optimized this way. */
+ if (node && node->binds_to_current_def_p ())
+ {
+ modref_summary *summary = get_modref_function_summary (node);
+ if (summary)
+ {
+ if (!modref_may_conflict (summary->loads, ref, tbaa_p))
+ {
+ alias_stats.modref_use_no_alias++;
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "ipa-modref: in %s,"
+ " call to %s does not use ",
+ cgraph_node::get
+ (current_function_decl)->dump_name (),
+ node->dump_name ());
+ print_generic_expr (dump_file, ref->ref);
+ fprintf (dump_file, " %i->%i\n",
+ ao_ref_base_alias_set (ref),
+ ao_ref_alias_set (ref));
+ }
+ goto process_args;
+ }
+ alias_stats.modref_use_may_alias++;
+ }
+ }
+ }
+
+ 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)
&& !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 && VAR_P (base) && TREE_STATIC (base))
{
struct cgraph_node *node = cgraph_node::get (callee);
- bitmap not_read;
+ bitmap read;
+ int id;
/* 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)))
+ && (id = ipa_reference_var_uid (base)) != -1
+ && (read = ipa_reference_get_read_global (node))
+ && !bitmap_bit_p (read, id))
goto process_args;
}
return true, otherwise return false. */
bool
-call_may_clobber_ref_p_1 (gcall *call, ao_ref *ref)
+call_may_clobber_ref_p_1 (gcall *call, ao_ref *ref, bool tbaa_p)
{
tree base;
tree callee;
break;
}
+ callee = gimple_call_fndecl (call);
+
+ if (callee != NULL_TREE && !ref->volatile_p)
+ {
+ struct cgraph_node *node = cgraph_node::get (callee);
+ if (node)
+ {
+ modref_summary *summary = get_modref_function_summary (node);
+ if (summary)
+ {
+ if (!modref_may_conflict (summary->stores, ref, tbaa_p))
+ {
+ alias_stats.modref_clobber_no_alias++;
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file,
+ "ipa-modref: in %s, "
+ "call to %s does not clobber ",
+ cgraph_node::get
+ (current_function_decl)->dump_name (),
+ node->dump_name ());
+ print_generic_expr (dump_file, ref->ref);
+ fprintf (dump_file, " %i->%i\n",
+ ao_ref_base_alias_set (ref),
+ ao_ref_alias_set (ref));
+ }
+ return false;
+ }
+ alias_stats.modref_clobber_may_alias++;
+ }
+ }
+ }
+
base = ao_ref_base (ref);
if (!base)
return true;
&& SSA_NAME_POINTS_TO_READONLY_MEMORY (TREE_OPERAND (base, 0)))
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 && VAR_P (base) && TREE_STATIC (base))
{
struct cgraph_node *node = cgraph_node::get (callee);
- bitmap not_written;
+ bitmap written;
+ int id;
if (node
- && (not_written = ipa_reference_get_not_written_global (node))
- && bitmap_bit_p (not_written, ipa_reference_var_uid (base)))
+ && (id = ipa_reference_var_uid (base)) != -1
+ && (written = ipa_reference_get_written_global (node))
+ && !bitmap_bit_p (written, id))
return false;
}
bool res;
ao_ref r;
ao_ref_init (&r, ref);
- res = call_may_clobber_ref_p_1 (call, &r);
+ res = call_may_clobber_ref_p_1 (call, &r, true);
if (res)
++alias_stats.call_may_clobber_ref_p_may_alias;
else
return true;
}
- return call_may_clobber_ref_p_1 (as_a <gcall *> (stmt), ref);
+ return call_may_clobber_ref_p_1 (as_a <gcall *> (stmt), ref, tbaa_p);
}
else if (gimple_assign_single_p (stmt))
{
/* Be conservative with non-call exceptions when the address might
be NULL. */
- if (flag_non_call_exceptions && pi->pt.null)
+ if (cfun->can_throw_non_call_exceptions && pi->pt.null)
return false;
/* Check that ptr points relative to obj. */
case BUILT_IN_MEMSET_CHK:
case BUILT_IN_STRNCPY:
case BUILT_IN_STPNCPY:
+ case BUILT_IN_CALLOC:
{
/* For a must-alias check we need to be able to constrain
the access properly. */
if (!ref->max_size_known_p ())
return false;
- tree dest = gimple_call_arg (stmt, 0);
- tree len = gimple_call_arg (stmt, 2);
+ tree dest;
+ tree len;
+
+ /* In execution order a calloc call will never kill
+ anything. However, DSE will (ab)use this interface
+ to ask if a calloc call writes the same memory locations
+ as a later assignment, memset, etc. So handle calloc
+ in the expected way. */
+ if (DECL_FUNCTION_CODE (callee) == BUILT_IN_CALLOC)
+ {
+ tree arg0 = gimple_call_arg (stmt, 0);
+ tree arg1 = gimple_call_arg (stmt, 1);
+ if (TREE_CODE (arg0) != INTEGER_CST
+ || TREE_CODE (arg1) != INTEGER_CST)
+ return false;
+
+ dest = gimple_call_lhs (stmt);
+ if (!dest)
+ return false;
+ len = fold_build2 (MULT_EXPR, TREE_TYPE (arg0), arg0, arg1);
+ }
+ else
+ {
+ dest = gimple_call_arg (stmt, 0);
+ len = gimple_call_arg (stmt, 2);
+ }
if (!poly_int_tree_p (len))
return false;
tree rbase = ref->base;
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 *),
+maybe_skip_until (gimple *phi, tree &target, basic_block target_bb,
+ ao_ref *ref, tree vuse, bool tbaa_p, unsigned int &limit,
+ bitmap *visited, bool abort_on_visited,
+ void *(*translate)(ao_ref *, tree, void *, translate_flags *),
+ translate_flags disambiguate_only,
void *data)
{
basic_block bb = gimple_bb (phi);
while (vuse != target)
{
gimple *def_stmt = SSA_NAME_DEF_STMT (vuse);
+ /* If we are searching for the target VUSE by walking up to
+ TARGET_BB dominating the original PHI we are finished once
+ we reach a default def or a definition in a block dominating
+ that block. Update TARGET and return. */
+ if (!target
+ && (gimple_nop_p (def_stmt)
+ || dominated_by_p (CDI_DOMINATORS,
+ target_bb, gimple_bb (def_stmt))))
+ {
+ target = vuse;
+ return true;
+ }
+
/* 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,
+ vuse = get_continuation_for_phi (def_stmt, ref, tbaa_p, limit,
visited, abort_on_visited,
- translate, data);
+ translate, data, disambiguate_only);
if (!vuse)
return false;
continue;
else
{
/* A clobbering statement or the end of the IL ends it failing. */
- ++*cnt;
- if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
+ if ((int)limit <= 0)
+ return false;
+ --limit;
+ if (stmt_may_clobber_ref_p_1 (def_stmt, ref, tbaa_p))
{
- bool disambiguate_only = true;
+ translate_flags tf = disambiguate_only;
if (translate
- && (*translate) (ref, vuse, data, &disambiguate_only) == NULL)
+ && (*translate) (ref, vuse, data, &tf) == NULL)
;
else
return false;
/* 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.
+ clobber REF. Decrements LIMIT for each alias disambiguation done
+ and aborts the walk, returning NULL_TREE if it reaches zero.
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,
+get_continuation_for_phi (gimple *phi, ao_ref *ref, bool tbaa_p,
+ unsigned int &limit, bitmap *visited,
bool abort_on_visited,
- void *(*translate)(ao_ref *, tree, void *, bool *),
- void *data)
+ void *(*translate)(ao_ref *, tree, void *,
+ translate_flags *),
+ void *data,
+ translate_flags disambiguate_only)
{
unsigned nargs = gimple_phi_num_args (phi);
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;
+ until we hit the immediate dominator. maybe_skip_until will
+ do that for us. */
+ basic_block dom = get_immediate_dominator (CDI_DOMINATORS, phi_bb);
- /* Then check against the found candidate. */
+ /* Then check against the (to be) 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,
+ else if (! maybe_skip_until (phi, arg0, dom, ref, arg1, tbaa_p,
+ limit, visited,
abort_on_visited,
- /* Do not translate when walking over
+ translate,
+ /* Do not valueize when walking over
backedges. */
dominated_by_p
(CDI_DOMINATORS,
gimple_bb (SSA_NAME_DEF_STMT (arg1)),
phi_bb)
- ? NULL : translate, data))
+ ? TR_DISAMBIGUATE
+ : disambiguate_only, data))
return NULL_TREE;
}
implement optimistic value-numbering for example. Note that the
VUSE argument is assumed to be valueized already.
+ LIMIT specifies the number of alias queries we are allowed to do,
+ the walk stops when it reaches zero and NULL is returned. LIMIT
+ is decremented by the number of alias queries (plus adjustments
+ done by the callbacks) upon return.
+
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 *),
+walk_non_aliased_vuses (ao_ref *ref, tree vuse, bool tbaa_p,
+ void *(*walker)(ao_ref *, tree, void *),
+ void *(*translate)(ao_ref *, tree, void *,
+ translate_flags *),
tree (*valueize)(tree),
- void *data)
+ unsigned &limit, void *data)
{
bitmap visited = NULL;
void *res;
- unsigned int cnt = 0;
bool translated = false;
timevar_push (TV_ALIAS_STMT_WALK);
gimple *def_stmt;
/* ??? Do we want to account this to TV_ALIAS_STMT_WALK? */
- res = (*walker) (ref, vuse, cnt, data);
+ res = (*walker) (ref, vuse, data);
/* Abort walk. */
if (res == (void *)-1)
{
if (gimple_nop_p (def_stmt))
break;
else if (gimple_code (def_stmt) == GIMPLE_PHI)
- vuse = get_continuation_for_phi (def_stmt, ref, &cnt,
+ vuse = get_continuation_for_phi (def_stmt, ref, tbaa_p, limit,
&visited, translated, translate, data);
else
{
- cnt++;
- if (stmt_may_clobber_ref_p_1 (def_stmt, ref))
+ if ((int)limit <= 0)
+ {
+ res = NULL;
+ break;
+ }
+ --limit;
+ if (stmt_may_clobber_ref_p_1 (def_stmt, ref, tbaa_p))
{
if (!translate)
break;
- bool disambiguate_only = false;
+ translate_flags disambiguate_only = TR_TRANSLATE;
res = (*translate) (ref, vuse, data, &disambiguate_only);
/* Failed lookup and translation. */
if (res == (void *)-1)
else if (res != NULL)
break;
/* Translation succeeded, continue walking. */
- translated = translated || !disambiguate_only;
+ translated = translated || disambiguate_only == TR_TRANSLATE;
}
vuse = gimple_vuse (def_stmt);
}
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