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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,
|
