Re: [PATCH] tree-optimization/103456 - Record only successes from object_sizes_set

[Jakub Jelinek <jakub@redhat.com>]

On Wed, Dec 01, 2021 at 09:47:21AM +0530, Siddhesh Poyarekar wrote:
> Avoid overwriting osi->changed if object_sizes_set does not update the
> size, so that a previous success in the same pass is not overwritten.
> This fixes the bootstrap-ubsan build config, which was failing due to
> incorrect object size.
> 
> Also completed a bootstrap on x86_64 which didn't show any new failures.
> 
> gcc/ChangeLog:
> 
> 	PR tree-optimization/103456
> 	* tree-object-size.c (merge_object_sizes): Update osi->changed
> 	only if object_sizes_set succeeded.
> 
> gcc/testsuite/ChangeLog:
> 
> 	PR tree-optimization/103456
> 	* gcc.dg/pr103456.c: New test.
> 
> Co-authored-by: Martin Liška <mliska@suse.cz>
> Signed-off-by: Siddhesh Poyarekar <siddhesh@gotplt.org>
> ---
>  gcc/testsuite/gcc.dg/pr103456.c | 21 +++++++++++++++++++++
>  gcc/tree-object-size.c          |  3 ++-
>  2 files changed, 23 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.dg/pr103456.c
> 
> diff --git a/gcc/testsuite/gcc.dg/pr103456.c b/gcc/testsuite/gcc.dg/pr103456.c
> new file mode 100644
> index 00000000000..20322fbaab1
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr103456.c

With -fsanitize=undefined that testcase belongs to
gcc/testsuite/gcc.dg/ubsan/pr103456.c, please move it there.

> @@ -0,0 +1,21 @@
> +/* PR tree-optimization/103456 */
> +/* { dg-do compile } */
> +/* { dg-options "-fsanitize=undefined -O -fdump-tree-objsz" } */
> +
> +static char *multilib_options = "m64/m32";
> +
> +void
> +used_arg_t (void)
> +{
> +  char *q = multilib_options;
> +  for (;;)
> +    {
> +      while (*q)
> +	q++;
> +      while (__builtin_strchr (q, '_') == 0)
> +	while (*q)
> +	  q++;
> +    }
> +}
> +
> +/* { dg-final { scan-tree-dump-not "maximum object size 0" "objsz1" } } */
> diff --git a/gcc/tree-object-size.c b/gcc/tree-object-size.c
> index 3780437ff91..b4881ef198f 100644
> --- a/gcc/tree-object-size.c
> +++ b/gcc/tree-object-size.c
> @@ -854,7 +854,8 @@ merge_object_sizes (struct object_size_info *osi, tree dest, tree orig,
>      orig_bytes = (offset > orig_bytes)
>  		 ? HOST_WIDE_INT_0U : orig_bytes - offset;
>  
> -  osi->changed = object_sizes_set (osi, varno, orig_bytes);
> +  if (object_sizes_set (osi, varno, orig_bytes))
> +    osi->changed = true;
>  
>    return bitmap_bit_p (osi->reexamine, SSA_NAME_VERSION (orig));
>  }

Otherwise LGTM.

	Jakub