Re: [v3 PATCH] Simplify vector ((VCE (a cmp b ? -1 : 0)) < 0) ? c : d to just (VCE ((a cmp b) ? (VCE c) : (VCE d))).

[Hongtao Liu <crazylht@gmail.com>]

On Mon, Dec 11, 2023 at 4:14 PM Richard Biener
<richard.guenther@gmail.com> wrote:
>
> On Mon, Dec 11, 2023 at 7:51 AM liuhongt <hongtao.liu@intel.com> wrote:
> >
> > > since you are looking at TYPE_PRECISION below you want
> > > VECTOR_INTIEGER_TYPE_P here as well?  The alternative
> > > would be to compare TYPE_SIZE.
> > >
> > > Some of the checks feel redundant but are probably good for
> > > documentation purposes.
> > >
> > > OK with using VECTOR_INTIEGER_TYPE_P
> > Actually, the data type doens't need to integer, .i.e x86 support vblendvps
> > so I'm using TYPE_SIZE here, the code is adjusted to
> >
> > && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (type)))
> > && (tree_to_uhwi (TYPE_SIZE (TREE_TYPE (type)))
> >    <= TYPE_PRECISION (TREE_TYPE (TREE_TYPE (@6))))
> >
> > Here's the updated patch.
> > Ok for trunk?
> >
> > When I'm working on PR112443, I notice there's some misoptimizations:
> > after we fold _mm{,256}_blendv_epi8/pd/ps into gimple, the backend
> > fails to combine it back to v{,p}blendv{v,ps,pd} since the pattern is
> > too complicated, so I think maybe we should hanlde it in the gimple
> > level.
> >
> > The dump is like
> >
> >   _1 = c_3(D) >= { 0, 0, 0, 0 };
> >   _2 = VEC_COND_EXPR <_1, { -1, -1, -1, -1 }, { 0, 0, 0, 0 }>;
> >   _7 = VIEW_CONVERT_EXPR<vector(32) char>(_2);
> >   _8 = VIEW_CONVERT_EXPR<vector(32) char>(b_6(D));
> >   _9 = VIEW_CONVERT_EXPR<vector(32) char>(a_5(D));
> >   _10 = _7 < { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
> >   _11 = VEC_COND_EXPR <_10, _8, _9>;
> >
> > It can be optimized to
> >
> >   _1 = c_2(D) >= { 0, 0, 0, 0 };
> >   _6 = VEC_COND_EXPR <_1, b_5(D), a_4(D)>;
> >
> > since _7 is either -1 or 0, the selection of _7 < 0 ? _8 : _9 should
> > be euqal to _1 ? b : a as long as TYPE_PRECISION of the component type
> > of the second VEC_COND_EXPR is less equal to the first one.
> > The patch add a gimple pattern to handle that.
> >
> > gcc/ChangeLog:
> >
> >         * match.pd (VCE (a cmp b ? -1 : 0) < 0) ? c : d ---> (VCE ((a
> >         cmp b) ? (VCE:c) : (VCE:d))): New gimple simplication.
> >
> > gcc/testsuite/ChangeLog:
> >
> >         * gcc.target/i386/avx512vl-blendv-3.c: New test.
> >         * gcc.target/i386/blendv-3.c: New test.
> > ---
> >  gcc/match.pd                                  | 23 ++++++++++
> >  .../gcc.target/i386/avx512vl-blendv-3.c       |  6 +++
> >  gcc/testsuite/gcc.target/i386/blendv-3.c      | 46 +++++++++++++++++++
> >  3 files changed, 75 insertions(+)
> >  create mode 100644 gcc/testsuite/gcc.target/i386/avx512vl-blendv-3.c
> >  create mode 100644 gcc/testsuite/gcc.target/i386/blendv-3.c
> >
> > diff --git a/gcc/match.pd b/gcc/match.pd
> > index 4d554ba4721..359c7b07dc3 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -5190,6 +5190,29 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> >   (if (optimize_vectors_before_lowering_p () && types_match (@0, @3))
> >    (vec_cond (bit_and @0 (bit_not @3)) @2 @1)))
> >
> > +/*  ((VCE (a cmp b ? -1 : 0)) < 0) ? c : d is just
> > +    (VCE ((a cmp b) ? (VCE c) : (VCE d))) when TYPE_PRECISION of the
> > +    component type of the outer vec_cond is greater equal the inner one.  */
> > +(for cmp (simple_comparison)
> > + (simplify
> > +  (vec_cond
> > +    (lt (view_convert@5 (vec_cond@6 (cmp@4 @0 @1)
> > +                                   integer_all_onesp
> > +                                   integer_zerop))
> > +         integer_zerop) @2 @3)
> > +  (if (VECTOR_INTEGER_TYPE_P (TREE_TYPE (@0))
> > +       && VECTOR_INTEGER_TYPE_P (TREE_TYPE (@5))
> > +       && !TYPE_UNSIGNED (TREE_TYPE (@5))
> > +       && VECTOR_TYPE_P (TREE_TYPE (@6))
> > +       && VECTOR_TYPE_P (type)
> > +       && tree_fits_uhwi_p (TYPE_SIZE (TREE_TYPE (type)))
> > +       && (tree_to_uhwi (TYPE_SIZE (TREE_TYPE (type)))
> > +         <= TYPE_PRECISION (TREE_TYPE (TREE_TYPE (@6))))
>
> sorry for nitpicking, but can you please use
>
>             && tree_int_cst_le (TYPE_SIZE (TREE_TYPE (type)),
>                                          TREE_TYPE (TREE_TYPE (@6)))
>
> thus not use precision on one and size on the other type?
>
> OK with that change.
Thanks, committed.
>
> Richard.
>
> > +       && TYPE_SIZE (type) == TYPE_SIZE (TREE_TYPE (@6)))
> > +   (with { tree vtype = TREE_TYPE (@6);}
> > +     (view_convert:type
> > +       (vec_cond @4 (view_convert:vtype @2) (view_convert:vtype @3)))))))
> > +
> >  /* 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.target/i386/avx512vl-blendv-3.c b/gcc/testsuite/gcc.target/i386/avx512vl-blendv-3.c
> > new file mode 100644
> > index 00000000000..2777e72ab5f
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/i386/avx512vl-blendv-3.c
> > @@ -0,0 +1,6 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-mavx512vl -mavx512bw -O2" } */
> > +/* { dg-final { scan-assembler-times {vp?blendv(?:b|p[sd])[ \t]*} 6 } } */
> > +/* { dg-final { scan-assembler-not {vpcmp} } } */
> > +
> > +#include "blendv-3.c"
> > diff --git a/gcc/testsuite/gcc.target/i386/blendv-3.c b/gcc/testsuite/gcc.target/i386/blendv-3.c
> > new file mode 100644
> > index 00000000000..fa0fb067a73
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/i386/blendv-3.c
> > @@ -0,0 +1,46 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-mavx2 -O2" } */
> > +/* { dg-final { scan-assembler-times {vp?blendv(?:b|p[sd])[ \t]*} 6 } } */
> > +/* { dg-final { scan-assembler-not {vpcmp} } } */
> > +
> > +#include <immintrin.h>
> > +
> > +__m256i
> > +foo (__m256i a, __m256i b, __m256i c)
> > +{
> > +  return _mm256_blendv_epi8 (a, b, ~c < 0);
> > +}
> > +
> > +__m256d
> > +foo1 (__m256d a, __m256d b, __m256i c)
> > +{
> > +  __m256i d = ~c < 0;
> > +  return _mm256_blendv_pd (a, b, (__m256d)d);
> > +}
> > +
> > +__m256
> > +foo2 (__m256 a, __m256 b, __m256i c)
> > +{
> > +  __m256i d = ~c < 0;
> > +  return _mm256_blendv_ps (a, b, (__m256)d);
> > +}
> > +
> > +__m128i
> > +foo4 (__m128i a, __m128i b, __m128i c)
> > +{
> > +  return _mm_blendv_epi8 (a, b, ~c < 0);
> > +}
> > +
> > +__m128d
> > +foo5 (__m128d a, __m128d b, __m128i c)
> > +{
> > +  __m128i d = ~c < 0;
> > +  return _mm_blendv_pd (a, b, (__m128d)d);
> > +}
> > +
> > +__m128
> > +foo6 (__m128 a, __m128 b, __m128i c)
> > +{
> > +  __m128i d = ~c < 0;
> > +  return _mm_blendv_ps (a, b, (__m128)d);
> > +}
> > --
> > 2.31.1
> >



-- 
BR,
Hongtao