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Date: Tue, 25 Apr 2023 11:52:42 +0200
From: Jan Hubicka <hubicka@ucw.cz>
To: Richard Biener <rguenther@suse.de>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] rtl-optimization/109585 - alias analysis typo
Message-ID: <ZEei6mwjCPdmS+eA@kam.mff.cuni.cz>
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> 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.
> 
> Bootstrapped and tested on x86_64-unknown-linux-gnu.
> 
> Honza, does this look OK?
Yes, sorry for that - that is a nasty pasto :(

Honza
> 
> Thanks,
> Richard.
> 
> 	PR rtl-optimization/109585
> 	* tree-ssa-alias.cc (aliasing_component_refs_p): Fix typo.
> 
> 	* gcc.dg/torture/pr109585.c: New testcase.
> ---
>  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
> 
> diff --git a/gcc/testsuite/gcc.dg/torture/pr109585.c b/gcc/testsuite/gcc.dg/torture/pr109585.c
> new file mode 100644
> index 00000000000..f92de7c1f2e
> --- /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;
> +}
> diff --git a/gcc/tree-ssa-alias.cc b/gcc/tree-ssa-alias.cc
> index 81bc51ed4ad..8a1ec9091fa 100644
> --- 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,
> -- 
> 2.35.3