Re: [PATCH][Backport][GCC10] Fix SSA corruption due to widening_mul opt on conflict across an abnormal edge [PR111407]

[Richard Biener <richard.guenther@gmail.com>]

On Mon, Apr 1, 2024 at 3:36 PM Qing Zhao <qing.zhao@oracle.com> wrote:
>
> This is a bug in tree-ssa-math-opts.c, when applying the widening mul
> optimization, the compiler needs to check whether the operand is in a
> ABNORMAL PHI, if YES, we should avoid the transformation.
>
>         PR tree-optimization/111407
>
> gcc/ChangeLog:
>
>         * tree-ssa-math-opts.c (convert_mult_to_widen): Avoid the transform
>         when one of the operands is subject to abnormal coalescing.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.dg/pr111407.c: New test.
>
> (cherry picked from commit 4aca1cfd6235090e48a53dab734437740671bbf3)
>
> bootstraped and regression tested on both aarch64 and x86.
>
> Okay for commit to GCC10?

Note the GCC 10 branch is closed.  If the patch boostraps/tests on the
11, 12 and 13
branches it is OK there.  You do not need approval to backport fixes
for _regressions_
if the patch cherry-picks without major edits and boostraps/tests OK.

Thanks,
Richard.

> thanks.
>
> Qing
> ---
>  gcc/testsuite/gcc.dg/pr111407.c | 21 +++++++++++++++++++++
>  gcc/tree-ssa-math-opts.c        |  8 ++++++++
>  2 files changed, 29 insertions(+)
>  create mode 100644 gcc/testsuite/gcc.dg/pr111407.c
>
> diff --git a/gcc/testsuite/gcc.dg/pr111407.c b/gcc/testsuite/gcc.dg/pr111407.c
> new file mode 100644
> index 000000000000..a171074753f9
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr111407.c
> @@ -0,0 +1,21 @@
> +/* PR tree-optimization/111407*/
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +enum { SEND_TOFILE } __sigsetjmp();
> +void fclose();
> +void foldergets();
> +void sendpart_stats(int *p1, int a1, int b1) {
> + int *a = p1;
> + fclose();
> + p1 = 0;
> + long t = b1;
> + if (__sigsetjmp()) {
> +   {
> +     long t1 = a1;
> +     a1+=1;
> +     fclose(a1*(long)t1);
> +   }
> + }
> + if (p1)
> +   fclose();
> +}
> diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
> index dd0b8c6f0577..47981da20e05 100644
> --- a/gcc/tree-ssa-math-opts.c
> +++ b/gcc/tree-ssa-math-opts.c
> @@ -2543,6 +2543,14 @@ convert_mult_to_widen (gimple *stmt, gimple_stmt_iterator *gsi)
>    if (!is_widening_mult_p (stmt, &type1, &rhs1, &type2, &rhs2))
>      return false;
>
> +  /* if any one of rhs1 and rhs2 is subject to abnormal coalescing,
> +     avoid the tranform. */
> +  if ((TREE_CODE (rhs1) == SSA_NAME
> +       && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs1))
> +      || (TREE_CODE (rhs2) == SSA_NAME
> +         && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs2)))
> +    return false;
> +
>    to_mode = SCALAR_INT_TYPE_MODE (type);
>    from_mode = SCALAR_INT_TYPE_MODE (type1);
>    if (to_mode == from_mode)
> --
> 2.31.1
>