On Fri, Jun 14, 2024 at 9:35 AM Levy Hsu <ad...@levyhsu.com> wrote:
>
> This patch updates the GCC x86 backend to efficiently handle
> odd, incrementally increasing permutations of BF16 vectors
> using the cvtne2ps2bf16 instruction.
> It modifies ix86_vectorize_vec_perm_const to support these operations
> and adds a specific predicate to ensure proper sequence handling.
>
> Bootstrapped and tested on x86_64-linux-gnu, OK for trunk?
Ok.
>
> gcc/ChangeLog:
>
> * config/i386/i386-expand.cc
> (ix86_vectorize_vec_perm_const): Convert BF to HI using subreg.
> * config/i386/predicates.md
> (vcvtne2ps2bf_parallel): New define_insn_and_split.
> * config/i386/sse.md
> (vpermt2_sepcial_bf16_shuffle_<mode>): New predicates matches odd
> increasing perm.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/vpermt2-special-bf16-shufflue.c: New test.
> ---
> gcc/config/i386/i386-expand.cc | 4 +--
> gcc/config/i386/predicates.md | 11 ++++++
> gcc/config/i386/sse.md | 35 +++++++++++++++++++
> .../i386/vpermt2-special-bf16-shufflue.c | 27 ++++++++++++++
> 4 files changed, 75 insertions(+), 2 deletions(-)
> create mode 100755
> gcc/testsuite/gcc.target/i386/vpermt2-special-bf16-shufflue.c
>
> diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
> index 312329e550b..3d599c0651a 100644
> --- a/gcc/config/i386/i386-expand.cc
> +++ b/gcc/config/i386/i386-expand.cc
> @@ -23657,8 +23657,8 @@ ix86_vectorize_vec_perm_const (machine_mode vmode,
> machine_mode op_mode,
> if (GET_MODE_SIZE (vmode) == 64 && !TARGET_EVEX512)
> return false;
>
> - /* For HF mode vector, convert it to HI using subreg. */
> - if (GET_MODE_INNER (vmode) == HFmode)
> + /* For HF and BF mode vector, convert it to HI using subreg. */
> + if (GET_MODE_INNER (vmode) == HFmode || GET_MODE_INNER (vmode) == BFmode)
> {
> machine_mode orig_mode = vmode;
> vmode = mode_for_vector (HImode,
> diff --git a/gcc/config/i386/predicates.md b/gcc/config/i386/predicates.md
> index 7afe3100cb7..1676c50de71 100644
> --- a/gcc/config/i386/predicates.md
> +++ b/gcc/config/i386/predicates.md
> @@ -2322,3 +2322,14 @@
>
> return true;
> })
> +
> +;; Check that each element is odd and incrementally increasing from 1
> +(define_predicate "vcvtne2ps2bf_parallel"
> + (and (match_code "const_vector")
> + (match_code "const_int" "a"))
> +{
> + for (int i = 0; i < XVECLEN (op, 0); ++i)
> + if (INTVAL (XVECEXP (op, 0, i)) != (2 * i + 1))
> + return false;
> + return true;
> +})
> diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
> index 680a46a0b08..5ddd1c0a778 100644
> --- a/gcc/config/i386/sse.md
> +++ b/gcc/config/i386/sse.md
> @@ -30698,3 +30698,38 @@
> "TARGET_AVXVNNIINT16"
> "vpdp<vpdpwprodtype>\t{%3, %2, %0|%0, %2, %3}"
> [(set_attr "prefix" "vex")])
> +
> +(define_mode_attr hi_cvt_bf
> + [(V8HI "v8bf") (V16HI "v16bf") (V32HI "v32bf")])
> +
> +(define_mode_attr HI_CVT_BF
> + [(V8HI "V8BF") (V16HI "V16BF") (V32HI "V32BF")])
> +
> +(define_insn_and_split "vpermt2_sepcial_bf16_shuffle_<mode>"
> + [(set (match_operand:VI2_AVX512F 0 "register_operand")
> + (unspec:VI2_AVX512F
> + [(match_operand:VI2_AVX512F 1 "vcvtne2ps2bf_parallel")
> + (match_operand:VI2_AVX512F 2 "register_operand")
> + (match_operand:VI2_AVX512F 3 "nonimmediate_operand")]
> + UNSPEC_VPERMT2))]
> + "TARGET_AVX512VL && TARGET_AVX512BF16 && ix86_pre_reload_split ()"
> + "#"
> + "&& 1"
> + [(const_int 0)]
> +{
> + rtx op0 = gen_reg_rtx (<HI_CVT_BF>mode);
> + operands[2] = lowpart_subreg (<ssePSmode>mode,
> + force_reg (<MODE>mode, operands[2]),
> + <MODE>mode);
> + operands[3] = lowpart_subreg (<ssePSmode>mode,
> + force_reg (<MODE>mode, operands[3]),
> + <MODE>mode);
> +
> + emit_insn (gen_avx512f_cvtne2ps2bf16_<hi_cvt_bf>(op0,
> + operands[3],
> + operands[2]));
> + emit_move_insn (operands[0], lowpart_subreg (<MODE>mode, op0,
> + <HI_CVT_BF>mode));
> + DONE;
> +}
> +[(set_attr "mode" "<sseinsnmode>")])
> diff --git a/gcc/testsuite/gcc.target/i386/vpermt2-special-bf16-shufflue.c
> b/gcc/testsuite/gcc.target/i386/vpermt2-special-bf16-shufflue.c
> new file mode 100755
> index 00000000000..5c65f2a9884
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/vpermt2-special-bf16-shufflue.c
> @@ -0,0 +1,27 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mavx512bf16 -mavx512vl" } */
> +/* { dg-final { scan-assembler-not "vpermi2b" } } */
> +/* { dg-final { scan-assembler-times "vcvtne2ps2bf16" 3 } } */
> +
> +typedef __bf16 v8bf __attribute__((vector_size(16)));
> +typedef __bf16 v16bf __attribute__((vector_size(32)));
> +typedef __bf16 v32bf __attribute__((vector_size(64)));
> +
> +v8bf foo0(v8bf a, v8bf b)
> +{
> + return __builtin_shufflevector(a, b, 1, 3, 5, 7, 9, 11, 13, 15);
> +}
> +
> +v16bf foo1(v16bf a, v16bf b)
> +{
> + return __builtin_shufflevector(a, b, 1, 3, 5, 7, 9, 11, 13, 15,
> + 17, 19, 21, 23, 25, 27, 29, 31);
> +}
> +
> +v32bf foo2(v32bf a, v32bf b)
> +{
> + return __builtin_shufflevector(a, b, 1, 3, 5, 7, 9, 11, 13, 15,
> + 17, 19, 21, 23, 25, 27, 29, 31,
> + 33, 35, 37, 39, 41, 43, 45, 47,
> + 49, 51, 53, 55, 57, 59, 61, 63);
> +}
> --
> 2.31.1
>
--
BR,
Hongtao
