testsuite: Add -fno-ivopts to gcc.dg/Wuse-after-free-2.c, PR108828

  Ok to commit?

I suggest that when committed I'll also set the bugzilla
entry in SUSPENDED mode, as opposed to RESOLVED.  I mean,
the issue isn't really solved; that'd be a patch improving
pointer tracking across ivopts.

-- >8 --
For cris-elf before this patch, ever since it was added,
this test gets:

Running /x/gcc/testsuite/gcc.dg/dg.exp ...
FAIL: gcc.dg/Wuse-after-free-2.c  (test for warnings, line 115)
FAIL: gcc.dg/Wuse-after-free-2.c  (test for warnings, line 116)

and comparing tree dumps with a native x86_64-pc-linux-gnu
run shows a suspicious difference in the "180t.ivopts" dump.
Indeed -fno-ivopts makes the warning appear for cris-elf
too.  It was suggested to simply add -fno-ivopts to the
test-flags, like before -fno-tree-loop-distribute-patterns
was added; thus.

	PR tree-optimization/108828
	* gcc.dg/Wuse-after-free-2.c: Add -fno-ivopts.
---
 gcc/testsuite/gcc.dg/Wuse-after-free-2.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
  

On Fri, Feb 24, 2023 at 5:38 PM Hans-Peter Nilsson via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Ok to commit?
>
> I suggest that when committed I'll also set the bugzilla
> entry in SUSPENDED mode, as opposed to RESOLVED.  I mean,
> the issue isn't really solved; that'd be a patch improving
> pointer tracking across ivopts.

OK.

Thanks,
Richard.

> -- >8 --
> For cris-elf before this patch, ever since it was added,
> this test gets:
>
> Running /x/gcc/testsuite/gcc.dg/dg.exp ...
> FAIL: gcc.dg/Wuse-after-free-2.c  (test for warnings, line 115)
> FAIL: gcc.dg/Wuse-after-free-2.c  (test for warnings, line 116)
>
> and comparing tree dumps with a native x86_64-pc-linux-gnu
> run shows a suspicious difference in the "180t.ivopts" dump.
> Indeed -fno-ivopts makes the warning appear for cris-elf
> too.  It was suggested to simply add -fno-ivopts to the
> test-flags, like before -fno-tree-loop-distribute-patterns
> was added; thus.
>
>         PR tree-optimization/108828
>         * gcc.dg/Wuse-after-free-2.c: Add -fno-ivopts.
> ---
>  gcc/testsuite/gcc.dg/Wuse-after-free-2.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/testsuite/gcc.dg/Wuse-after-free-2.c b/gcc/testsuite/gcc.dg/Wuse-after-free-2.c
> index 68ec75845cec..ebc051690db5 100644
> --- a/gcc/testsuite/gcc.dg/Wuse-after-free-2.c
> +++ b/gcc/testsuite/gcc.dg/Wuse-after-free-2.c
> @@ -1,6 +1,6 @@
>  /* PR middle-end/104232 - spurious -Wuse-after-free after conditional free
>     { dg-do compile }
> -   { dg-options "-O2 -Wall -fno-tree-loop-distribute-patterns" }  */
> +   { dg-options "-O2 -Wall -fno-tree-loop-distribute-patterns -fno-ivopts" }  */
>
>  void free (void*);
>
> @@ -108,7 +108,8 @@ int warn_cond_loop (char *p)
>    char *q = p;
>
>    /*  -fno-tree-loop-distribute-patterns ensures this does not get converted
> -      into rawmemchr (making q and p unrelated).  */
> +      into rawmemchr (making q and p unrelated).  Also, -fno-ivopts is required
> +      for some targets, to not lose track of the pointer.  */
>    while (*q)
>      ++q;
>
> --
> 2.30.2
>