[PATCH, rs6000] Disable gimple fold for float or double vec_minmax when fast-math is not set

Bill Schmidt wschmidt@linux.ibm.com
Wed Aug 25 12:34:44 GMT 2021


Hi Haochen,

Thanks for the updates!  This looks good to me; please await Segher's 
response.

Bill

On 8/25/21 2:06 AM, HAO CHEN GUI wrote:
> Hi,
>
>       I refined the patch according to Bill's advice. I pasted the
> ChangeLog and diff file here. If it doesn't work, please let me know.
> Thanks.
>
> 2021-08-25 Haochen Gui <guihaoc@linux.ibm.com>
>
> gcc/
>       * config/rs6000/rs6000-call.c (rs6000_gimple_fold_builtin):
>       Modify the VSX_BUILTIN_XVMINDP, ALTIVEC_BUILTIN_VMINFP,
>       VSX_BUILTIN_XVMAXDP, ALTIVEC_BUILTIN_VMAXFP expansions.
>
> gcc/testsuite/
>       * gcc.target/powerpc/vec-minmax-1.c: New test.
>       * gcc.target/powerpc/vec-minmax-2.c: Likewise.
>
> diff --git a/gcc/config/rs6000/rs6000-call.c
> b/gcc/config/rs6000/rs6000-call.c
> index b4e13af4dc6..90527734ceb 100644
> --- a/gcc/config/rs6000/rs6000-call.c
> +++ b/gcc/config/rs6000/rs6000-call.c
> @@ -12159,6 +12159,11 @@ rs6000_gimple_fold_builtin
> (gimple_stmt_iterator *gsi)
>          return true;
>        /* flavors of vec_min.  */
>        case VSX_BUILTIN_XVMINDP:
> +    case ALTIVEC_BUILTIN_VMINFP:
> +      if (!flag_finite_math_only || flag_signed_zeros)
> +    return false;
> +      /* Fall through to MIN_EXPR.  */
> +      gcc_fallthrough ();
>        case P8V_BUILTIN_VMINSD:
>        case P8V_BUILTIN_VMINUD:
>        case ALTIVEC_BUILTIN_VMINSB:
> @@ -12167,7 +12172,6 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator
> *gsi)
>        case ALTIVEC_BUILTIN_VMINUB:
>        case ALTIVEC_BUILTIN_VMINUH:
>        case ALTIVEC_BUILTIN_VMINUW:
> -    case ALTIVEC_BUILTIN_VMINFP:
>          arg0 = gimple_call_arg (stmt, 0);
>          arg1 = gimple_call_arg (stmt, 1);
>          lhs = gimple_call_lhs (stmt);
> @@ -12177,6 +12181,11 @@ rs6000_gimple_fold_builtin
> (gimple_stmt_iterator *gsi)
>          return true;
>        /* flavors of vec_max.  */
>        case VSX_BUILTIN_XVMAXDP:
> +    case ALTIVEC_BUILTIN_VMAXFP:
> +      if (!flag_finite_math_only || flag_signed_zeros)
> +    return false;
> +      /* Fall through to MAX_EXPR.  */
> +      gcc_fallthrough ();
>        case P8V_BUILTIN_VMAXSD:
>        case P8V_BUILTIN_VMAXUD:
>        case ALTIVEC_BUILTIN_VMAXSB:
> @@ -12185,7 +12194,6 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator
> *gsi)
>        case ALTIVEC_BUILTIN_VMAXUB:
>        case ALTIVEC_BUILTIN_VMAXUH:
>        case ALTIVEC_BUILTIN_VMAXUW:
> -    case ALTIVEC_BUILTIN_VMAXFP:
>          arg0 = gimple_call_arg (stmt, 0);
>          arg1 = gimple_call_arg (stmt, 1);
>          lhs = gimple_call_lhs (stmt);
> diff --git a/gcc/testsuite/gcc.target/powerpc/vec-minmax-1.c
> b/gcc/testsuite/gcc.target/powerpc/vec-minmax-1.c
> new file mode 100644
> index 00000000000..da92f059aea
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/vec-minmax-1.c
> @@ -0,0 +1,53 @@
> +/* { dg-do compile { target { powerpc64le-*-* } } } */
> +/* { dg-require-effective-target powerpc_p9vector_ok } */
> +/* { dg-options "-O2 -mdejagnu-cpu=power9" } */
> +/* { dg-final { scan-assembler-times {\mxvmaxdp\M} 1 } } */
> +/* { dg-final { scan-assembler-times {\mxvmaxsp\M} 1 } } */
> +/* { dg-final { scan-assembler-times {\mxvmindp\M} 1 } } */
> +/* { dg-final { scan-assembler-times {\mxvminsp\M} 1 } } */
> +
> +/* This test verifies that float or double vec_min/max are bound to
> +   xv[min|max][d|s]p instructions when fast-math is not set.  */
> +
> +
> +#include <altivec.h>
> +
> +#ifdef _BIG_ENDIAN
> +   const int PREF_D = 0;
> +#else
> +   const int PREF_D = 1;
> +#endif
> +
> +double vmaxd (double a, double b)
> +{
> +  vector double va = vec_promote (a, PREF_D);
> +  vector double vb = vec_promote (b, PREF_D);
> +  return vec_extract (vec_max (va, vb), PREF_D);
> +}
> +
> +double vmind (double a, double b)
> +{
> +  vector double va = vec_promote (a, PREF_D);
> +  vector double vb = vec_promote (b, PREF_D);
> +  return vec_extract (vec_min (va, vb), PREF_D);
> +}
> +
> +#ifdef _BIG_ENDIAN
> +   const int PREF_F = 0;
> +#else
> +   const int PREF_F = 3;
> +#endif
> +
> +float vmaxf (float a, float b)
> +{
> +  vector float va = vec_promote (a, PREF_F);
> +  vector float vb = vec_promote (b, PREF_F);
> +  return vec_extract (vec_max (va, vb), PREF_F);
> +}
> +
> +float vminf (float a, float b)
> +{
> +  vector float va = vec_promote (a, PREF_F);
> +  vector float vb = vec_promote (b, PREF_F);
> +  return vec_extract (vec_min (va, vb), PREF_F);
> +}
> diff --git a/gcc/testsuite/gcc.target/powerpc/vec-minmax-2.c
> b/gcc/testsuite/gcc.target/powerpc/vec-minmax-2.c
> new file mode 100644
> index 00000000000..d318b933181
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/vec-minmax-2.c
> @@ -0,0 +1,51 @@
> +/* { dg-do compile { target { powerpc64le-*-* } } } */
> +/* { dg-require-effective-target powerpc_p9vector_ok } */
> +/* { dg-options "-O2 -mdejagnu-cpu=power9 -ffast-math" } */
> +/* { dg-final { scan-assembler-times {\mxsmaxcdp\M} 2 } } */
> +/* { dg-final { scan-assembler-times {\mxsmincdp\M} 2 } } */
> +
> +/* This test verifies that float or double vec_min/max can be converted
> +   to scalar comparison when fast-math is set.  */
> +
> +
> +#include <altivec.h>
> +
> +#ifdef _BIG_ENDIAN
> +   const int PREF_D = 0;
> +#else
> +   const int PREF_D = 1;
> +#endif
> +
> +double vmaxd (double a, double b)
> +{
> +  vector double va = vec_promote (a, PREF_D);
> +  vector double vb = vec_promote (b, PREF_D);
> +  return vec_extract (vec_max (va, vb), PREF_D);
> +}
> +
> +double vmind (double a, double b)
> +{
> +  vector double va = vec_promote (a, PREF_D);
> +  vector double vb = vec_promote (b, PREF_D);
> +  return vec_extract (vec_min (va, vb), PREF_D);
> +}
> +
> +#ifdef _BIG_ENDIAN
> +   const int PREF_F = 0;
> +#else
> +   const int PREF_F = 3;
> +#endif
> +
> +float vmaxf (float a, float b)
> +{
> +  vector float va = vec_promote (a, PREF_F);
> +  vector float vb = vec_promote (b, PREF_F);
> +  return vec_extract (vec_max (va, vb), PREF_F);
> +}
> +
> +float vminf (float a, float b)
> +{
> +  vector float va = vec_promote (a, PREF_F);
> +  vector float vb = vec_promote (b, PREF_F);
> +  return vec_extract (vec_min (va, vb), PREF_F);
> +}
>
> On 25/8/2021 上午 6:40, Segher Boessenkool wrote:
>> Hi!
>>
>> On Tue, Aug 24, 2021 at 03:04:26PM -0500, Bill Schmidt wrote:
>>> On 8/24/21 3:52 AM, HAO CHEN GUI wrote:
>>> Thanks for this patch!  In the future, if you can put your ChangeLog and
>>> patch inline in your post, it makes it easier to review.  (Otherwise we
>>> have to manually copy it into our response and manipulate it to look
>>> quoted, etc.)
>> It is encoded even, making it impossible to easily apply the patch, etc.
>>
>>>> diff --git a/gcc/config/rs6000/rs6000-call.c
>>>> b/gcc/config/rs6000/rs6000-call.c index b4e13af4dc6..90527734ceb
>>>> 100644 --- a/gcc/config/rs6000/rs6000-call.c +++
>>>> b/gcc/config/rs6000/rs6000-call.c @@ -12159,6 +12159,11 @@
>>>> rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi) return true; /*
>>>> flavors of vec_min. */ case VSX_BUILTIN_XVMINDP: + case
>> format=flawed :-(
>>
>>
>> Segher


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