On Mon, Apr 28, 2014 at 9:48 AM, Evgeny Stupachenko <evstu...@gmail.com> wrote:
> Hi,
>
> The patch enables use of "palignr with perm" instead of "2 pshufb, or
> and perm" at AVX2 for some cases.
>
> Bootstrapped and passes make check on x86.
>
> Is it ok?
>
> 2014-04-28 Evgeny Stupachenko <evstu...@gmail.com>
>
> * config/i386/i386.c (expand_vec_perm_1): Try AVX2 vpshufb.
> * config/i386/i386.c (expand_vec_perm_palignr): Extend to use AVX2
> PALINGR instruction.
Can you add testcases to verify that AVX2 vpshufb and paligngr are
properly generated?
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index 88142a8..ae80477 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -42807,6 +42807,8 @@ expand_vec_perm_pshufb (struct expand_vec_perm_d *d)
> return true;
> }
>
> +static bool expand_vec_perm_vpshufb2_vpermq (struct expand_vec_perm_d *d);
> +
> /* A subroutine of ix86_expand_vec_perm_builtin_1. Try to instantiate D
> in a single instruction. */
>
> @@ -42946,6 +42948,10 @@ expand_vec_perm_1 (struct expand_vec_perm_d *d)
> if (expand_vec_perm_pshufb (d))
> return true;
>
> + /* Try the AVX2 vpshufb. */
> + if (expand_vec_perm_vpshufb2_vpermq (d))
> + return true;
> +
> /* Try the AVX512F vpermi2 instructions. */
> rtx vec[64];
> enum machine_mode mode = d->vmode;
> @@ -43004,7 +43010,7 @@ expand_vec_perm_pshuflw_pshufhw (struct
> expand_vec_perm_d *d)
> }
>
> /* A subroutine of ix86_expand_vec_perm_builtin_1. Try to simplify
> - the permutation using the SSSE3 palignr instruction. This succeeds
> + the permutation using the SSSE3/AVX2 palignr instruction. This succeeds
> when all of the elements in PERM fit within one vector and we merely
> need to shift them down so that a single vector permutation has a
> chance to succeed. */
> @@ -43015,14 +43021,20 @@ expand_vec_perm_palignr (struct expand_vec_perm_d
> *d)
> unsigned i, nelt = d->nelt;
> unsigned min, max;
> bool in_order, ok;
> - rtx shift, target;
> + rtx shift, shift1, target, tmp;
> struct expand_vec_perm_d dcopy;
>
> - /* Even with AVX, palignr only operates on 128-bit vectors. */
> - if (!TARGET_SSSE3 || GET_MODE_SIZE (d->vmode) != 16)
> + /* PALIGNR of 2 256-bits registers on AVX2 costs only 2 instructions:
> + PERM and PALIGNR. It is more profitable than 2 PSHUFB and PERM.
> + PALIGNR of 2 128-bits registers takes only 1 instrucion. */
> + if (!TARGET_SSSE3 || (GET_MODE_SIZE (d->vmode) != 16 &&
^^^ This should
be only on the next lined.
> + GET_MODE_SIZE (d->vmode) != 32))
> + return false;
> + /* Only AVX2 or higher support PALIGNR on 256-bits registers. */
> + if (!TARGET_AVX2 && (GET_MODE_SIZE (d->vmode) == 32))
^ No need for '(' here.
Or you can use
if ((!TARGET_SSSE3 || GET_MODE_SIZE (d->vmode) != 16)
&& (!TARGET_AVX2 || GET_MODE_SIZE (d->vmode) != 32))
> return false;
>
> - min = nelt, max = 0;
> + min = 2 * nelt, max = 0;
^^^^^^^^^^^^^^^^^^^^^^^^^^ Will this change 128bit vector code?
> for (i = 0; i < nelt; ++i)
> {
> unsigned e = d->perm[i];
> @@ -43041,9 +43053,34 @@ expand_vec_perm_palignr (struct expand_vec_perm_d *d)
>
> dcopy = *d;
> shift = GEN_INT (min * GET_MODE_BITSIZE (GET_MODE_INNER (d->vmode)));
> - target = gen_reg_rtx (TImode);
> - emit_insn (gen_ssse3_palignrti (target, gen_lowpart (TImode, d->op1),
> - gen_lowpart (TImode, d->op0), shift));
> + shift1 = GEN_INT ((min - nelt / 2) *
> + GET_MODE_BITSIZE (GET_MODE_INNER (d->vmode)));
> +
> + if (GET_MODE_SIZE (d->vmode) != 32)
> + {
> + target = gen_reg_rtx (TImode);
> + emit_insn (gen_ssse3_palignrti (target, gen_lowpart (TImode, d->op1),
> + gen_lowpart (TImode, d->op0), shift));
> + }
> + else
> + {
> + target = gen_reg_rtx (V2TImode);
> + tmp = gen_reg_rtx (V4DImode);
> + emit_insn (gen_avx2_permv2ti (tmp,
> + gen_lowpart (V4DImode, d->op0),
> + gen_lowpart (V4DImode, d->op1),
> + GEN_INT (33)));
> + if (min < nelt / 2)
> + emit_insn (gen_avx2_palignrv2ti (target,
> + gen_lowpart (V2TImode, tmp),
> + gen_lowpart (V2TImode, d->op0),
> + shift));
> + else
> + emit_insn (gen_avx2_palignrv2ti (target,
> + gen_lowpart (V2TImode, d->op1),
> + gen_lowpart (V2TImode, tmp),
> + shift1));
> + }
>
> dcopy.op0 = dcopy.op1 = gen_lowpart (d->vmode, target);
> dcopy.one_operand_p = true;
>
>
> Evgeny
--
H.J.
