[PATCH] i386: Auto vectorize sdot_prod, usdot_prod with VNNI instruction.

Hongtao Liu crazylht@gmail.com
Thu Nov 4 06:34:15 GMT 2021


On Thu, Nov 4, 2021 at 9:50 AM Hongyu Wang via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Hi,
>
> AVX512VNNI/AVXVNNI has vpdpwssd for HImode, vpdpbusd for QImode, so
> Adjust HImode sdot_prod expander and add QImode usdot_prod expander
> to enhance vectorization for dotprod.
>
> Bootstraped/regtested on x86_64-pc-linux-gnu{-m32,} and sde.
> Ok for master?
LGTM.
>
> gcc/ChangeLog:
>
>         * config/i386/sse.md (VI2_AVX512VNNIBW): New mode iterator.
>         (VI1_AVX512VNNI): Likewise.
>         (SDOT_VPDP_SUF): New mode_attr.
>         (VI1SI): Likewise.
>         (vi1si): Likewise.
>         (sdot_prod<mode>): Use VI2_AVX512F iterator, expand to
>         vpdpwssd when VNNI targets available.
>         (usdot_prod<mode>): New expander for vector QImode.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/i386/vnni-auto-vectorize-1.c: New test.
>         * gcc.target/i386/vnni-auto-vectorize-2.c: Ditto.
> ---
>
> diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
> index 2764a250229..22435e5d036 100644
> --- a/gcc/config/i386/sse.md
> +++ b/gcc/config/i386/sse.md
> @@ -500,6 +500,9 @@
>  (define_mode_iterator VI1_AVX512F
>    [(V64QI "TARGET_AVX512F") (V32QI "TARGET_AVX") V16QI])
>
> +(define_mode_iterator VI1_AVX512VNNI
> +  [(V64QI "TARGET_AVX512VNNI") (V32QI "TARGET_AVX2") V16QI])
> +
>  (define_mode_iterator VI12_256_512_AVX512VL
>    [V64QI (V32QI "TARGET_AVX512VL")
>     V32HI (V16HI "TARGET_AVX512VL")])
> @@ -510,6 +513,10 @@
>  (define_mode_iterator VI2_AVX512F
>    [(V32HI "TARGET_AVX512F") (V16HI "TARGET_AVX2") V8HI])
>
> +(define_mode_iterator VI2_AVX512VNNIBW
> +  [(V32HI "TARGET_AVX512BW || TARGET_AVX512VNNI")
> +   (V16HI "TARGET_AVX2") V8HI])
> +
>  (define_mode_iterator VI4_AVX
>    [(V8SI "TARGET_AVX") V4SI])
>
> @@ -14798,19 +14805,37 @@
>  (define_mode_attr SDOT_PMADD_SUF
>    [(V32HI "512v32hi") (V16HI "") (V8HI "")])
>
> +(define_mode_attr SDOT_VPDP_SUF
> +  [(V32HI "v16si") (V16HI "v8si") (V8HI "v4si")])
> +
>  (define_expand "sdot_prod<mode>"
>    [(match_operand:<sseunpackmode> 0 "register_operand")
> -   (match_operand:VI2_AVX2 1 "register_operand")
> -   (match_operand:VI2_AVX2 2 "register_operand")
> +   (match_operand:VI2_AVX512VNNIBW 1 "register_operand")
> +   (match_operand:VI2_AVX512VNNIBW 2 "register_operand")
>     (match_operand:<sseunpackmode> 3 "register_operand")]
>    "TARGET_SSE2"
>  {
> -  rtx t = gen_reg_rtx (<sseunpackmode>mode);
> -  emit_insn (gen_<sse2_avx2>_pmaddwd<SDOT_PMADD_SUF> (t, operands[1], operands[2]));
> -  emit_insn (gen_rtx_SET (operands[0],
> -                         gen_rtx_PLUS (<sseunpackmode>mode,
> -                                       operands[3], t)));
> -  DONE;
> +  /* Try with vnni instructions.  */
> +  if ((<MODE_SIZE> == 64 && TARGET_AVX512VNNI)
> +      || (<MODE_SIZE> < 64
> +         && ((TARGET_AVX512VNNI && TARGET_AVX512VL) || TARGET_AVXVNNI)))
> +    {
> +      operands[1] = lowpart_subreg (<sseunpackmode>mode, operands[1], <MODE>mode);
> +      operands[2] = lowpart_subreg (<sseunpackmode>mode, operands[2], <MODE>mode);
> +      emit_insn (gen_rtx_SET (operands[0], operands[3]));
> +      emit_insn (gen_vpdpwssd_<SDOT_VPDP_SUF> (operands[0], operands[3],
> +                                              operands[1], operands[2]));
> +    }
> +    /* Otherwise use pmaddwd + paddd.  */
> +    else
> +    {
> +      rtx t = gen_reg_rtx (<sseunpackmode>mode);
> +      emit_insn (gen_<sse2_avx2>_pmaddwd<SDOT_PMADD_SUF> (t, operands[1], operands[2]));
> +      emit_insn (gen_rtx_SET (operands[0],
> +                             gen_rtx_PLUS (<sseunpackmode>mode,
> +                                           operands[3], t)));
> +    }
> +    DONE;
>  })
>
>  ;; Normally we use widen_mul_even/odd, but combine can't quite get it all
> @@ -27065,6 +27090,29 @@
>     [(set_attr ("prefix") ("evex"))
>     (set_attr "mode" "<sseinsnmode>")])
>
> +(define_mode_attr VI1SI
> + [(V64QI "V16SI") (V32QI "V8SI") (V16QI "V4SI")])
> +
> +(define_mode_attr vi1si
> + [(V64QI "v16si") (V32QI "v8si") (V16QI "v4si")])
> +
> +(define_expand "usdot_prod<mode>"
> +  [(match_operand:<VI1SI> 0 "register_operand")
> +   (match_operand:VI1_AVX512VNNI 1 "register_operand")
> +   (match_operand:VI1_AVX512VNNI 2 "register_operand")
> +   (match_operand:<VI1SI> 3 "register_operand")]
> +  "(<MODE_SIZE> == 64
> +    ||((TARGET_AVX512VNNI && TARGET_AVX512VL)
> +           || TARGET_AVXVNNI))"
> +{
> +  operands[1] = lowpart_subreg (<VI1SI>mode, operands[1], <MODE>mode);
> +  operands[2] = lowpart_subreg (<VI1SI>mode, operands[2], <MODE>mode);
> +  emit_insn (gen_rtx_SET (operands[0], operands[3]));
> +  emit_insn (gen_vpdpbusd_<vi1si> (operands[0], operands[3],
> +                                 operands[1], operands[2]));
> +  DONE;
> +})
> +
>  (define_insn "vpdpbusd_v16si"
>    [(set (match_operand:V16SI 0 "register_operand" "=v")
>         (unspec:V16SI
> diff --git a/gcc/testsuite/gcc.target/i386/vnni-auto-vectorize-1.c b/gcc/testsuite/gcc.target/i386/vnni-auto-vectorize-1.c
> new file mode 100644
> index 00000000000..844f37ddfc1
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/vnni-auto-vectorize-1.c
> @@ -0,0 +1,30 @@
> +/* { dg-do compile } */
> +/* { dg-options "-mavx512f -mavx512vnni -mavx512vl -O2" } */
> +
> +/* { dg-final { scan-assembler "vpdpwssd\t" } } */
> +/* { dg-final { scan-assembler "vpdpbusd\t" } } */
> +/* { dg-final { scan-assembler-not "vpmaddwd\t" } } */
> +
> +int __attribute__((noinline, noclone, optimize("tree-vectorize")))
> +sdot_prod_hi (short * restrict a, short * restrict b,
> +             int c, int n)
> +{
> +  int i;
> +  for (i = 0; i < n; i++)
> +    {
> +      c += ((int) a[i] * (int) b[i]);
> +    }
> +  return c;
> +}
> +
> +int __attribute__((noinline, noclone, optimize("tree-vectorize")))
> +usdot_prod_qi (unsigned char * restrict a, char *restrict b,
> +              int c, int n)
> +{
> +  int i;
> +  for (i = 0; i < n; i++)
> +    {
> +      c += ((int) a[i] * (int) b[i]);
> +    }
> +  return c;
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/vnni-auto-vectorize-2.c b/gcc/testsuite/gcc.target/i386/vnni-auto-vectorize-2.c
> new file mode 100644
> index 00000000000..dc8047d5644
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/vnni-auto-vectorize-2.c
> @@ -0,0 +1,72 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -mavx512vnni -mavx512vl" } */
> +/* { dg-require-effective-target avx512vnni } */
> +/* { dg-require-effective-target avx512vl } */
> +
> +static void vnni_test (void);
> +#define DO_TEST vnni_test
> +#define AVX512VNNI
> +#define AVX512VL
> +#include "avx512f-check.h"
> +#include "vnni-auto-vectorize-1.c"
> +
> +#define N 256
> +unsigned char a_u8[N];
> +char b_i8[N];
> +short a_i16[N], b_i16[N];
> +int i8_exp, i8_ref, i16_exp, i16_ref;
> +
> +int __attribute__((noinline, noclone, optimize("no-tree-vectorize")))
> +sdot_prod_hi_scalar (short * restrict a, short * restrict b,
> +                    int c, int n)
> +{
> +  int i;
> +  for (i = 0; i < n; i++)
> +    {
> +      c += ((int) a[i] * (int) b[i]);
> +    }
> +  return c;
> +}
> +
> +int __attribute__((noinline, noclone, optimize("no-tree-vectorize")))
> +usdot_prod_qi_scalar (unsigned char * restrict a, char *restrict b,
> +              int c, int n)
> +{
> +  int i;
> +  for (i = 0; i < n; i++)
> +    {
> +      c += ((int) a[i] * (int) b[i]);
> +    }
> +  return c;
> +}
> +
> +void init()
> +{
> +  int i;
> +
> +  i8_exp = i8_ref = 127;
> +  i16_exp = i16_ref = 65535;
> +
> +  for (i = 0; i < N; i++)
> +    {
> +      a_u8[i] = (i + 3) % 256;
> +      b_i8[i] = (i + 1) % 128;
> +      a_i16[i] = i * 2;
> +      b_i16[i] = -i + 2;
> +    }
> +}
> +
> +static void vnni_test()
> +{
> +  init ();
> +  i16_exp = sdot_prod_hi (a_i16, b_i16, i16_exp, N);
> +  i16_ref = sdot_prod_hi_scalar (a_i16, b_i16, i16_ref, N);
> +  if (i16_exp != i16_ref)
> +    abort ();
> +
> +  init ();
> +  i8_exp = usdot_prod_qi (a_u8, b_i8, i8_exp, N);
> +  i8_ref = usdot_prod_qi_scalar (a_u8, b_i8, i8_ref, N);
> +  if (i8_exp != i8_ref)
> +    abort ();
> +}
> --
> 2.18.1
>


-- 
BR,
Hongtao


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