Optimize A < B ? A : B to MIN_EXPR.

Similar for A < B ? B : A to MAX_EXPR.
There're codes in the frontend to optimize such pattern but failed to
handle testcase in the PR since it's exposed at gimple level when
folding backend builtins.

pr95906 now can be optimized to MAX_EXPR as it's commented in the
testcase.

// FIXME: this should further optimize to a MAX_EXPR
 typedef signed char v16i8 __attribute__((vector_size(16)));
 v16i8 f(v16i8 a, v16i8 b)


Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
Ok for trunk? (or maybe wait for GCC 15).

gcc/ChangeLog:

	PR target/104401
	* match.pd (A < B ? A : B -> MIN_EXPR): New patten match.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr104401.c: New test.
	* gcc.dg/tree-ssa/pr95906.c: Adjust testcase.
---
 gcc/match.pd                             | 20 ++++++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr95906.c  |  3 +--
 gcc/testsuite/gcc.target/i386/pr104401.c | 27 ++++++++++++++++++++++++
 3 files changed, 48 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr104401.c

On Tue, Dec 19, 2023 at 6:39 AM liuhongt <hongtao.liu@intel.com> wrote:
>
> Similar for A < B ? B : A to MAX_EXPR.
> There're codes in the frontend to optimize such pattern but failed to
> handle testcase in the PR since it's exposed at gimple level when
> folding backend builtins.
>
> pr95906 now can be optimized to MAX_EXPR as it's commented in the
> testcase.
>
> // FIXME: this should further optimize to a MAX_EXPR
>  typedef signed char v16i8 __attribute__((vector_size(16)));
>  v16i8 f(v16i8 a, v16i8 b)
>
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for trunk? (or maybe wait for GCC 15).

I wonder if you can amend the existing patterns instead by iterating
over cond/vec_cond.  There are quite some (look for uses of
minmax_from_comparison) that could be adapted to vectors.

The ones matching the simple form you match are

#if GIMPLE
/* A >= B ? A : B -> max (A, B) and friends.  The code is still
   in fold_cond_expr_with_comparison for GENERIC folding with
   some extra constraints.  */
(for cmp (eq ne le lt unle unlt ge gt unge ungt uneq ltgt)
 (simplify
  (cond (cmp:c (nop_convert1?@c0 @0) (nop_convert2?@c1 @1))
        (convert3? @0) (convert4? @1))
  (if (!HONOR_SIGNED_ZEROS (type)
...

I think.  Consider at least placing the new patterns next to that.

> gcc/ChangeLog:
>
>         PR target/104401
>         * match.pd (A < B ? A : B -> MIN_EXPR): New patten match.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/i386/pr104401.c: New test.
>         * gcc.dg/tree-ssa/pr95906.c: Adjust testcase.
> ---
>  gcc/match.pd                             | 20 ++++++++++++++++++
>  gcc/testsuite/gcc.dg/tree-ssa/pr95906.c  |  3 +--
>  gcc/testsuite/gcc.target/i386/pr104401.c | 27 ++++++++++++++++++++++++
>  3 files changed, 48 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr104401.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index d57e29bfe1d..9584a70aa3d 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -5263,6 +5263,26 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>       (view_convert:type
>         (vec_cond @4 (view_convert:vtype @2) (view_convert:vtype @3)))))))
>
> +/* Optimize A < B ? A : B to MIN (A, B)
> +           A > B ? A : B to MAX (A, B).  */
> +(for cmp (lt le gt ge)
> +     minmax (min min max max)
> +     MINMAX (MIN_EXPR MIN_EXPR MAX_EXPR MAX_EXPR)
> + (simplify
> +  (vec_cond (cmp @0 @1) @0 @1)
> +   (if (VECTOR_INTEGER_TYPE_P (type)
> +       && target_supports_op_p (type, MINMAX, optab_vector))
> +    (minmax @0 @1))))
> +
> +(for cmp (lt le gt ge)
> +     minmax (max max min min)
> +     MINMAX (MAX_EXPR MAX_EXPR MIN_EXPR MIN_EXPR)
> + (simplify
> +  (vec_cond (cmp @0 @1) @1 @0)
> +   (if (VECTOR_INTEGER_TYPE_P (type)
> +       && target_supports_op_p (type, MINMAX, optab_vector))
> +    (minmax @0 @1))))
> +
>  /* c1 ? c2 ? a : b : b  -->  (c1 & c2) ? a : b  */
>  (simplify
>   (vec_cond @0 (vec_cond:s @1 @2 @3) @3)
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr95906.c b/gcc/testsuite/gcc.dg/tree-ssa/pr95906.c
> index 3d820a58e93..d15670f3e9e 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/pr95906.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr95906.c
> @@ -1,7 +1,6 @@
>  /* { dg-do compile } */
>  /* { dg-options "-O2 -fdump-tree-forwprop3-raw -w -Wno-psabi" } */
>
> -// FIXME: this should further optimize to a MAX_EXPR
>  typedef signed char v16i8 __attribute__((vector_size(16)));
>  v16i8 f(v16i8 a, v16i8 b)
>  {
> @@ -10,4 +9,4 @@ v16i8 f(v16i8 a, v16i8 b)
>  }
>
>  /* { dg-final { scan-tree-dump-not "bit_(and|ior)_expr" "forwprop3" } } */
> -/* { dg-final { scan-tree-dump-times "vec_cond_expr" 1 "forwprop3" } } */
> +/* { dg-final { scan-tree-dump-times "max_expr" 1 "forwprop3" } } */
> diff --git a/gcc/testsuite/gcc.target/i386/pr104401.c b/gcc/testsuite/gcc.target/i386/pr104401.c
> new file mode 100644
> index 00000000000..8ce7ff88d9e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr104401.c
> @@ -0,0 +1,27 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -msse4.1" } */
> +/* { dg-final { scan-assembler-times "pminsd" 2 } } */
> +/* { dg-final { scan-assembler-times "pmaxsd" 2 } } */
> +
> +#include <smmintrin.h>
> +
> +__m128i min32(__m128i value, __m128i input)
> +{
> +  return _mm_blendv_epi8(input, value, _mm_cmplt_epi32(value, input));
> +}
> +
> +__m128i max32(__m128i value, __m128i input)
> +{
> +  return _mm_blendv_epi8(input, value, _mm_cmpgt_epi32(value, input));
> +}
> +
> +__m128i min32_1(__m128i value, __m128i input)
> +{
> +  return _mm_blendv_epi8(input, value, _mm_cmpgt_epi32(input, value));
> +}
> +
> +__m128i max32_1(__m128i value, __m128i input)
> +{
> +  return _mm_blendv_epi8(input, value, _mm_cmplt_epi32(input, value));
> +}
> +
> --
> 2.31.1
>