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

David Edelsohn dje.gcc@gmail.com
Tue Nov 2 00:21:45 GMT 2021


Hi, Hao

Neither the inlined patch nor the attached patch seem to contain the
change to rs6000-call.c.  I only see the new testcases.

Please resend the complete patch.

Thanks David

On Mon, Nov 1, 2021 at 2:48 AM HAO CHEN GUI <guihaoc@linux.ibm.com> wrote:
>
> Hi,
>
>   This patch disables gimple folding for VSX_BUILTIN_XVMINDP, VSX_BUILTIN_XVMAXDP, ALTIVEC_BUILTIN_VMINFP and  ALTIVEC_BUILTIN_VMAXFP when fast-math is not set.  With the gimple folding is enabled, the four built-ins will be implemented by c-type instructions - xs[min|max]cdp on P9 and P10 if they can be converted to scalar comparisons.  While they are implemented by xv[min|max][s|d]p on P8 and P7 as P8 and P7 don't have corresponding scalar comparison instructions.  The patch binds these four built-ins to xv[min|max][s|d]p when fast-math is not set. The two new test cases illustrate it.
>
>   ALTIVEC_BUILTIN_VMINFP and  ALTIVEC_BUILTIN_VMAXFP are not implemented by vminfp or vmaxfp.
>
> rs6000-builtin.def:BU_ALTIVEC_2 (VMAXFP,              "vmaxfp",         CONST, smaxv4sf3)
>
> rs6000-builtin.def:BU_ALTIVEC_2 (VMINFP,              "vminfp",         CONST, sminv4sf3)
>
> Bootstrapped and tested on powerpc64le-linux with no regressions. Is this okay for trunk? Any recommendations? Thanks a lot.
>
>
> ChangeLog
>
> 2021-11-01 Haochen Gui <guihaoc@linux.ibm.com>
>
> gcc/
>         * config/rs6000/rs6000-call.c (rs6000_gimple_fold_builtin): Disable
>         gimple fold for VSX_BUILTIN_XVMINDP, ALTIVEC_BUILTIN_VMINFP,
>         VSX_BUILTIN_XVMAXDP, ALTIVEC_BUILTIN_VMAXFP when fast-math is not
>         set.
>
> gcc/testsuite/
>         * gcc.target/powerpc/vec-minmax-1.c: New test.
>         * gcc.target/powerpc/vec-minmax-2.c: Likewise.
>
>
> patch.diff
>
> 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..e238659c9be
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/vec-minmax-1.c
> @@ -0,0 +1,52 @@
> +/* { 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..149275d8709
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/vec-minmax-2.c
> @@ -0,0 +1,50 @@
> +/* { 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);
> +}


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