a6d689632c
While improving access path analysis a typo happened. Now it can happen that gcc misscompiles. The patch is fixing the issue. However, also other gcc versions 10.2+ are affected. They also should be bumped or the fix should be backported. For more bug information have a look at: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109585 Signed-off-by: Nick Hainke <vincent@systemli.org>
70 lines
1.8 KiB
Diff
70 lines
1.8 KiB
Diff
From bb406a6aea336966681927a27f54ee89c4fd4ea1 Mon Sep 17 00:00:00 2001
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From: Richard Biener <rguenther@suse.de>
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Date: Mon, 24 Apr 2023 13:31:07 +0200
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Subject: [PATCH] rtl-optimization/109585 - alias analysis typo
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When r10-514-gc6b84edb6110dd2b4fb improved access path analysis
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it introduced a typo that triggers when there's an access to a
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trailing array in the first access path leading to false
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disambiguation.
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PR rtl-optimization/109585
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* tree-ssa-alias.cc (aliasing_component_refs_p): Fix typo.
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* gcc.dg/torture/pr109585.c: New testcase.
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(cherry picked from commit 6d4bd27a60447c7505cb4783e675e98a191a8904)
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---
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gcc/testsuite/gcc.dg/torture/pr109585.c | 33 +++++++++++++++++++++++++
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gcc/tree-ssa-alias.cc | 2 +-
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2 files changed, 34 insertions(+), 1 deletion(-)
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create mode 100644 gcc/testsuite/gcc.dg/torture/pr109585.c
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--- /dev/null
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+++ b/gcc/testsuite/gcc.dg/torture/pr109585.c
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@@ -0,0 +1,33 @@
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+/* { dg-do run } */
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+
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+#include <stdlib.h>
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+
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+struct P {
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+ long v;
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+ struct P *n;
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+};
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+
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+struct F {
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+ long x;
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+ struct P fam[];
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+};
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+
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+int __attribute__((noipa))
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+f(struct F *f, int i)
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+{
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+ struct P *p = f->fam;
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+ asm("" : "+r"(f): "r"(p));
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+ p->v = 0;
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+ p->n = 0;
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+ return f->fam->n != 0;
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+}
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+
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+int
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+main()
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+{
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+ struct F *m = malloc (sizeof (long) + 2 * sizeof (struct P));
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+ m->fam[0].n = &m->fam[1];
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+ if (f (m, 0))
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+ abort ();
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+ return 0;
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+}
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--- a/gcc/tree-ssa-alias.cc
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+++ b/gcc/tree-ssa-alias.cc
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@@ -1330,7 +1330,7 @@ aliasing_component_refs_p (tree ref1,
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/* If we didn't find a common base, try the other way around. */
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if (cmp_outer <= 0
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|| (end_struct_ref1
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- && compare_type_sizes (TREE_TYPE (end_struct_ref1), type1) <= 0))
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+ && compare_type_sizes (TREE_TYPE (end_struct_ref1), type2) <= 0))
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{
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int res = aliasing_component_refs_walk (ref2, type2, base2,
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offset2, max_size2,
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