On Thu, Jun 20, 2019 at 4:16 PM Jan Hubicka <hubi...@ucw.cz> wrote:
>
> Hi,
> as discussed earlier this patch drops ref2_is_decl from
> aliasing_component_refs. This parameter makes it to assume that all
> access path may not continue by reference to DECL which is not true
> because in gimple memory model we allow to store value of completely
> unrealted type to it. I have also constructed an (invalid C IMO)
> testcase (which fails on GCC for ages, but works for ICC)
>
> Bootstrapped/regtested x86_64-linux, will commit it shortly.
OK.
Richard.
> * tree-ssa-alias.c (aliasing_component_refs_p): Remove ref2_is_decl
> parameter; it has no use in gimple memory model.
> (indirect_ref_may_alias_decl_p): Update.
> * gcc.c-torture/execute/alias-access-path-1.c: New testcase.
> Index: tree-ssa-alias.c
> ===================================================================
> --- tree-ssa-alias.c (revision 272507)
> +++ tree-ssa-alias.c (working copy)
> @@ -850,8 +850,7 @@ type_has_components_p (tree type)
>
> /* 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. */
>
> @@ -863,8 +862,7 @@ aliasing_component_refs_p (tree ref1,
> 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
> @@ -982,7 +980,7 @@ aliasing_component_refs_p (tree ref1,
> if (TREE_CODE (TREE_TYPE (base1)) == ARRAY_TYPE
> && (!TYPE_SIZE (TREE_TYPE (base1))
> || TREE_CODE (TYPE_SIZE (TREE_TYPE (base1))) != INTEGER_CST
> - || (ref == base2 && !ref2_is_decl)))
> + || ref == base2))
> {
> ++alias_stats.aliasing_component_refs_p_may_alias;
> return true;
> @@ -1041,7 +1039,7 @@ aliasing_component_refs_p (tree ref1,
> if (TREE_CODE (TREE_TYPE (base2)) == ARRAY_TYPE
> && (!TYPE_SIZE (TREE_TYPE (base2))
> || TREE_CODE (TYPE_SIZE (TREE_TYPE (base2))) != INTEGER_CST
> - || (ref == base1 && !ref2_is_decl)))
> + || ref == base1))
> {
> ++alias_stats.aliasing_component_refs_p_may_alias;
> return true;
> @@ -1089,8 +1087,7 @@ aliasing_component_refs_p (tree ref1,
> return true;
> }
> /* If this is ptr vs. decl then we know there is no ptr ... decl path. */
> - if (!ref2_is_decl
> - && compare_type_sizes (TREE_TYPE (ref1), type2) >= 0
> + if (compare_type_sizes (TREE_TYPE (ref1), type2) >= 0
> && (!end_struct_ref2
> || compare_type_sizes (TREE_TYPE (ref1),
> TREE_TYPE (end_struct_ref2)) >= 0)
> @@ -1554,13 +1551,7 @@ indirect_ref_may_alias_decl_p (tree ref1
> offset1, max_size1,
> ref2,
> ref2_alias_set, base2_alias_set,
> - offset2, max_size2,
> - /* Only if the other reference is actual
> - decl we can safely check only
> toplevel
> - part of access path 1. */
> - same_type_for_tbaa (TREE_TYPE (dbase2),
> - TREE_TYPE (base2))
> - == 1);
> + offset2, max_size2);
>
> return true;
> }
> @@ -1675,7 +1666,7 @@ indirect_refs_may_alias_p (tree ref1 ATT
> offset1, max_size1,
> ref2,
> ref2_alias_set, base2_alias_set,
> - offset2, max_size2, false);
> + offset2, max_size2);
>
> return true;
> }
> Index: testsuite/gcc.c-torture/execute/alias-access-path-1.c
> ===================================================================
> --- testsuite/gcc.c-torture/execute/alias-access-path-1.c (nonexistent)
> +++ testsuite/gcc.c-torture/execute/alias-access-path-1.c (working copy)
> @@ -0,0 +1,19 @@
> +/* Test that variable
> + int val;
> + may hold value of tyope "struct c" which has same size.
> + This is valid in GIMPLE memory model. */
> +
> +struct a {int val;} a={1},a2;
> +struct b {struct a a;};
> +int val;
> +struct c {struct b b;} *cptr=(void *)&val;
> +
> +int
> +main(void)
> +{
> + cptr->b.a=a;
> + val = 2;
> + a2=cptr->b.a;
> + if (a2.val == a.val)
> + __builtin_abort ();
> +}
