RE: [PATCH] Optimize vpermtiw/b to vpunpcklqdq for certain cases.

[Liu, Hongtao via Gcc-patches]

> -----Original Message-----
> From: Uros Bizjak <ubiz...@gmail.com>
> Sent: Friday, May 13, 2022 4:15 PM
> To: Liu, Hongtao <hongtao....@intel.com>
> Cc: gcc-patches@gcc.gnu.org
> Subject: Re: [PATCH] Optimize vpermtiw/b to vpunpcklqdq for certain cases.
> 
> On Fri, May 13, 2022 at 9:16 AM liuhongt <hongtao....@intel.com> wrote:
> >
> > Assembly Optimization like:
> > -       vmovq   %xmm0, %xmm2
> > -       vmovdqa .LC0(%rip), %xmm0
> >         vmovq   %xmm1, %xmm1
> > -       vpermi2w        %xmm1, %xmm2, %xmm0
> > +       vmovq   %xmm0, %xmm0
> > +       vpunpcklqdq     %xmm1, %xmm0, %xmm0
> >
> > ...
> >
> > -.LC0:
> > -       .value  0
> > -       .value  1
> > -       .value  2
> > -       .value  3
> > -       .value  8
> > -       .value  9
> > -       .value  10
> > -       .value  11
> >
> >
> > Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> > Ok for trunk?
> >
> > gcc/ChangeLog:
> >
> >         PR target/105033
> >         * config/i386/sse.md (*vec_concatv4si): Extend to ..
> >         (*vec_concat<mode>): .. V16QI and V8HImode.
> >         (*vec_concatv16qi_permt2): New pre_reload define_insn_and_split.
> >         (*vec_concatv8hi_permt2): Ditto.
> >
> > gcc/testsuite/ChangeLog:
> >
> >         * gcc.target/i386/pr105033.c: New test.
> > ---
> >  gcc/config/i386/sse.md                   | 62 ++++++++++++++++++++++--
> >  gcc/testsuite/gcc.target/i386/pr105033.c | 27 +++++++++++
> >  2 files changed, 84 insertions(+), 5 deletions(-)  create mode 100644
> > gcc/testsuite/gcc.target/i386/pr105033.c
> >
> > diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md index
> > a63df0d0b1f..2e417e47d20 100644
> > --- a/gcc/config/i386/sse.md
> > +++ b/gcc/config/i386/sse.md
> > @@ -19600,11 +19600,11 @@ (define_insn "*vec_concatv2si"
> >     (set_attr "type" "sselog,ssemov,sselog,ssemov,mmxcvt,mmxmov")
> >     (set_attr "mode" "TI,TI,V4SF,SF,DI,DI")])
> >
> > -(define_insn "*vec_concatv4si"
> > -  [(set (match_operand:V4SI 0 "register_operand"       "=x,v,x,x,v")
> > -       (vec_concat:V4SI
> > -         (match_operand:V2SI 1 "register_operand"     " 0,v,0,0,v")
> > -         (match_operand:V2SI 2 "nonimmediate_operand" " x,v,x,m,m")))]
> > +(define_insn "*vec_concat<mode>"
> > +  [(set (match_operand:VI124_128 0 "register_operand"       "=x,v,x,x,v")
> > +       (vec_concat:VI124_128
> > +         (match_operand:<ssehalfvecmode> 1 "register_operand"     " 
> > 0,v,0,0,v")
> > +         (match_operand:<ssehalfvecmode> 2 "nonimmediate_operand" "
> > +x,v,x,m,m")))]
> >    "TARGET_SSE"
> >    "@
> >     punpcklqdq\t{%2, %0|%0, %2}
> > @@ -19617,6 +19617,58 @@ (define_insn "*vec_concatv4si"
> >     (set_attr "prefix" "orig,maybe_evex,orig,orig,maybe_evex")
> >     (set_attr "mode" "TI,TI,V4SF,V2SF,V2SF")])
> >
> > +(define_insn_and_split "*vec_concatv16qi_permt2"
> > +  [(set (match_operand:V16QI 0 "register_operand")
> > +       (unspec:V16QI
> > +         [(const_vector:V16QI [(const_int 0) (const_int 1)
> > +                               (const_int 2) (const_int 3)
> > +                               (const_int 4) (const_int 5)
> > +                               (const_int 6) (const_int 7)
> > +                               (const_int 16) (const_int 17)
> > +                               (const_int 18) (const_int 19)
> > +                               (const_int 20) (const_int 21)
> > +                               (const_int 22) (const_int 23)])
> > +          (match_operand:V16QI 1 "register_operand")
> > +          (match_operand:V16QI 2 "nonimmediate_operand")]
> > +         UNSPEC_VPERMT2))]
> > +  "TARGET_AVX512VL && TARGET_AVX512VBMI"
> 
> You need "&& ix86_pre_reload_split ()" here, because a pseudo can be
> generated via force_reg.
> 
will change.
> > +  "#"
> > +  "&& 1"
> > +  [(set (match_dup 0)
> > +       (vec_concat:V16QI (match_dup 1) (match_dup 2)))] {
> > +  operands[1] = lowpart_subreg (V8QImode,
> > +                               force_reg (V16QImode, operands[1]),
> > +                               V16QImode);
> > +  if (!MEM_P (operands[2]))
> > +    operands[2] = force_reg (V16QImode, operands[2]);
> 
> Are you sure there are no subregs possible in operand[2]? To stay on the safe
> side, use force_reg unconditionally, it will also force subregs to reg, 
> avoiding
> failure with the following lowpart_subreg.
When it's MEM, not need to force_reg.
> 
> Uros.
> 
> > +  operands[2] = lowpart_subreg (V8QImode, operands[2], V16QImode);
> > +})
> > +
> > +(define_insn_and_split "*vec_concatv8hi_permt2"
> > +  [(set (match_operand:V8HI 0 "register_operand")
> > +       (unspec:V8HI
> > +         [(const_vector:V8HI [(const_int 0) (const_int 1)
> > +                               (const_int 2) (const_int 3)
> > +                               (const_int 8) (const_int 9)
> > +                               (const_int 10) (const_int 11)])
> > +          (match_operand:V8HI 1 "register_operand")
> > +          (match_operand:V8HI 2 "nonimmediate_operand")]
> > +         UNSPEC_VPERMT2))]
> > +  "TARGET_AVX512VL && TARGET_AVX512BW"
> > +  "#"
> > +  "&& 1"
> > +  [(set (match_dup 0)
> > +       (vec_concat:V8HI (match_dup 1) (match_dup 2)))] {
> > +  operands[1] = lowpart_subreg (V4HImode,
> > +                               force_reg (V8HImode, operands[1]),
> > +                               V8HImode);
> > +  if (!MEM_P (operands[2]))
> > +    operands[2] = force_reg (V8HImode, operands[2]);
> > +  operands[2] = lowpart_subreg (V4HImode, operands[2], V8HImode);
> > +})
> > +
> >  (define_insn "*vec_concat<mode>_0"
> >    [(set (match_operand:VI124_128 0 "register_operand"       "=v,x")
> >         (vec_concat:VI124_128
> > diff --git a/gcc/testsuite/gcc.target/i386/pr105033.c
> > b/gcc/testsuite/gcc.target/i386/pr105033.c
> > new file mode 100644
> > index 00000000000..ab05e3b3bc8
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/i386/pr105033.c
> > @@ -0,0 +1,27 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-march=sapphirerapids -O2" } */
> > +/* { dg-final { scan-assembler-times {vpunpcklqdq[ \t]+} 3 } } */
> > +/* { dg-final { scan-assembler-not {vpermi2[wb][ \t]+} } } */
> > +
> > +typedef _Float16 v8hf __attribute__((vector_size (16))); typedef
> > +_Float16 v4hf __attribute__((vector_size (8))); typedef short v8hi
> > +__attribute__((vector_size (16))); typedef short v4hi
> > +__attribute__((vector_size (8))); typedef char v16qi
> > +__attribute__((vector_size (16))); typedef char v8qi
> > +__attribute__((vector_size (8)));
> > +
> > +v8hf foo (v4hf a, v4hf b)
> > +{
> > +  return __builtin_shufflevector (a, b, 0, 1, 2, 3, 4, 5, 6, 7); }
> > +
> > +v8hi foo2 (v4hi a, v4hi b)
> > +{
> > +  return __builtin_shufflevector (a, b, 0, 1, 2, 3, 4, 5, 6, 7); }
> > +
> > +v16qi foo3 (v8qi a, v8qi b)
> > +{
> > +  return __builtin_shufflevector (a, b, 0, 1, 2, 3, 4, 5, 6, 7,
> > +                                 8, 9, 10, 11, 12, 13, 14, 15); }
> > --
> > 2.18.1
> >