Re: [PATCH] i386: Fix a pasto in ix86_expand_int_sse_cmp [PR114339]

[Uros Bizjak <ubizjak@gmail.com>]

On Fri, Mar 15, 2024 at 9:50 AM Jakub Jelinek <jakub@redhat.com> wrote:
>
> Hi!
>
> In r13-3803-gfa271afb58 I've added an optimization for LE/LEU/GE/GEU
> comparison against CONST_VECTOR.  As the comments say:
>          /* x <= cst can be handled as x < cst + 1 unless there is
>             wrap around in cst + 1.  */
> ...
>                      /* For LE punt if some element is signed maximum.  */
> ...
>                  /* For LEU punt if some element is unsigned maximum.  */
> and
>          /* x >= cst can be handled as x > cst - 1 unless there is
>             wrap around in cst - 1.  */
> ...
>                      /* For GE punt if some element is signed minimum.  */
> ...
>                  /* For GEU punt if some element is zero.  */
> Apparently I wrote the GE/GEU (second case) first and then
> copied/adjusted it for LE/LEU, most of the adjustments look correct, but
> I've left if (code == GE) comparison when testing if it should punt for
> signed maximum.  That condition is never true, because this is in
> switch (code) { ... case LE: case LEU: block and we really meant to
> be what the comment says, for LE punt if some element is signed maximum,
> as then cst + 1 wraps around.
>
> The following patch fixes the pasto.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2024-03-15  Jakub Jelinek  <jakub@redhat.com>
>
>         PR target/114339
>         * config/i386/i386-expand.cc (ix86_expand_int_sse_cmp) <case LE>: Fix
>         a pasto, compare code against LE rather than GE.
>
>         * gcc.target/i386/pr114339.c: New test.

OK.

Thanks,
Uros.

>
> --- gcc/config/i386/i386-expand.cc.jj   2024-03-07 08:34:21.043802912 +0100
> +++ gcc/config/i386/i386-expand.cc      2024-03-14 22:55:57.321842686 +0100
> @@ -4690,7 +4690,7 @@ ix86_expand_int_sse_cmp (rtx dest, enum
>                   rtx elt = CONST_VECTOR_ELT (cop1, i);
>                   if (!CONST_INT_P (elt))
>                     break;
> -                 if (code == GE)
> +                 if (code == LE)
>                     {
>                       /* For LE punt if some element is signed maximum.  */
>                       if ((INTVAL (elt) & (GET_MODE_MASK (eltmode) >> 1))
> --- gcc/testsuite/gcc.target/i386/pr114339.c.jj 2024-03-14 22:58:04.739076025 +0100
> +++ gcc/testsuite/gcc.target/i386/pr114339.c    2024-03-14 22:38:59.736972124 +0100
> @@ -0,0 +1,20 @@
> +/* PR target/114339 */
> +/* { dg-do run } */
> +/* { dg-options "-O2 -Wno-psabi" } */
> +/* { dg-additional-options "-mavx" { target avx_runtime } } */
> +
> +typedef long long V __attribute__((vector_size (16)));
> +
> +__attribute__((noipa)) V
> +foo (V a)
> +{
> +  return a <= (V) {0, __LONG_LONG_MAX__ };
> +}
> +
> +int
> +main ()
> +{
> +  V t = foo ((V) { 0, 0 });
> +  if (t[0] != -1LL || t[1] != -1LL)
> +    __builtin_abort ();
> +}
>
>         Jakub
>