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- From bb406a6aea336966681927a27f54ee89c4fd4ea1 Mon Sep 17 00:00:00 2001
- From: Richard Biener <rguenther@suse.de>
- Date: Mon, 24 Apr 2023 13:31:07 +0200
- Subject: [PATCH] rtl-optimization/109585 - alias analysis typo
- When r10-514-gc6b84edb6110dd2b4fb improved access path analysis
- it introduced a typo that triggers when there's an access to a
- trailing array in the first access path leading to false
- disambiguation.
- PR rtl-optimization/109585
- * tree-ssa-alias.cc (aliasing_component_refs_p): Fix typo.
- * gcc.dg/torture/pr109585.c: New testcase.
- (cherry picked from commit 6d4bd27a60447c7505cb4783e675e98a191a8904)
- ---
- gcc/testsuite/gcc.dg/torture/pr109585.c | 33 +++++++++++++++++++++++++
- gcc/tree-ssa-alias.cc | 2 +-
- 2 files changed, 34 insertions(+), 1 deletion(-)
- create mode 100644 gcc/testsuite/gcc.dg/torture/pr109585.c
- --- /dev/null
- +++ b/gcc/testsuite/gcc.dg/torture/pr109585.c
- @@ -0,0 +1,33 @@
- +/* { dg-do run } */
- +
- +#include <stdlib.h>
- +
- +struct P {
- + long v;
- + struct P *n;
- +};
- +
- +struct F {
- + long x;
- + struct P fam[];
- +};
- +
- +int __attribute__((noipa))
- +f(struct F *f, int i)
- +{
- + struct P *p = f->fam;
- + asm("" : "+r"(f): "r"(p));
- + p->v = 0;
- + p->n = 0;
- + return f->fam->n != 0;
- +}
- +
- +int
- +main()
- +{
- + struct F *m = malloc (sizeof (long) + 2 * sizeof (struct P));
- + m->fam[0].n = &m->fam[1];
- + if (f (m, 0))
- + abort ();
- + return 0;
- +}
- --- a/gcc/tree-ssa-alias.cc
- +++ b/gcc/tree-ssa-alias.cc
- @@ -1330,7 +1330,7 @@ aliasing_component_refs_p (tree ref1,
- /* If we didn't find a common base, try the other way around. */
- if (cmp_outer <= 0
- || (end_struct_ref1
- - && compare_type_sizes (TREE_TYPE (end_struct_ref1), type1) <= 0))
- + && compare_type_sizes (TREE_TYPE (end_struct_ref1), type2) <= 0))
- {
- int res = aliasing_component_refs_walk (ref2, type2, base2,
- offset2, max_size2,
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