Re: [PATCH 1/2] x86: correct / simplify @vec_extract_hi_<mode> and vec_extract_hi_v32qi

[Hongtao Liu <crazylht@gmail.com>]

On Wed, Jul 5, 2023 at 4:00 PM Jan Beulich via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> The middle alternative each was unusable without enabling AVX512DQ (in
> addition to AVX512VL), which is entirely unrelated here. The last
> alternative is usable with AVX512VL only (due to type restrictions on
> what may be put in the upper 16 YMM registers), and hence is pointlessly
> forcing 512-bit mode (without actually reflecting that in the "mode"
> attribute).
Ok.
>
> gcc/
>
>         * config/i386/sse.md (@vec_extract_hi_<mode>): Drop last
>         alternative. Switch new last alternative's "isa" attribute to
>         "avx512vl".
>         (vec_extract_hi_v32qi): Likewise.
> ---
> Like elsewhere I suspect "prefix_extra" is bogus here and should be
> dropped.
>
> Is "sselog1" actually appropriate here? Extracts are special forms of
> moves after all, not logical operations. Even "sseshuf1" would seem to
> come closer.
Honestly, I don't know why it's marked as sselog1, but looking at the
code,  almost all vec_extract patterns are marked as sselog1, guess
it's originally from pextr.
Agree that it's should be more close to shuffle instructions.
>
> --- a/gcc/config/i386/sse.md
> +++ b/gcc/config/i386/sse.md
> @@ -12029,9 +12029,9 @@
>    "operands[1] = gen_lowpart (<ssehalfvecmode>mode, operands[1]);")
>
>  (define_insn "@vec_extract_hi_<mode>"
> -  [(set (match_operand:<ssehalfvecmode> 0 "nonimmediate_operand" "=xm,vm,vm")
> +  [(set (match_operand:<ssehalfvecmode> 0 "nonimmediate_operand" "=xm,vm")
>         (vec_select:<ssehalfvecmode>
> -         (match_operand:V16_256 1 "register_operand" "x,v,v")
> +         (match_operand:V16_256 1 "register_operand" "x,v")
>           (parallel [(const_int 8) (const_int 9)
>                      (const_int 10) (const_int 11)
>                      (const_int 12) (const_int 13)
> @@ -12039,13 +12039,12 @@
>    "TARGET_AVX"
>    "@
>     vextract%~128\t{$0x1, %1, %0|%0, %1, 0x1}
> -   vextracti32x4\t{$0x1, %1, %0|%0, %1, 0x1}
> -   vextracti32x4\t{$0x1, %g1, %0|%0, %g1, 0x1}"
> +   vextracti32x4\t{$0x1, %1, %0|%0, %1, 0x1}"
>    [(set_attr "type" "sselog1")
>     (set_attr "prefix_extra" "1")
>     (set_attr "length_immediate" "1")
> -   (set_attr "isa" "*,avx512dq,avx512f")
> -   (set_attr "prefix" "vex,evex,evex")
> +   (set_attr "isa" "*,avx512vl")
> +   (set_attr "prefix" "vex,evex")
>     (set_attr "mode" "OI")])
>
>  (define_insn_and_split "vec_extract_lo_v64qi"
> @@ -12144,9 +12143,9 @@
>    "operands[1] = gen_lowpart (V16QImode, operands[1]);")
>
>  (define_insn "vec_extract_hi_v32qi"
> -  [(set (match_operand:V16QI 0 "nonimmediate_operand" "=xm,vm,vm")
> +  [(set (match_operand:V16QI 0 "nonimmediate_operand" "=xm,vm")
>         (vec_select:V16QI
> -         (match_operand:V32QI 1 "register_operand" "x,v,v")
> +         (match_operand:V32QI 1 "register_operand" "x,v")
>           (parallel [(const_int 16) (const_int 17)
>                      (const_int 18) (const_int 19)
>                      (const_int 20) (const_int 21)
> @@ -12158,13 +12157,12 @@
>    "TARGET_AVX"
>    "@
>     vextract%~128\t{$0x1, %1, %0|%0, %1, 0x1}
> -   vextracti32x4\t{$0x1, %1, %0|%0, %1, 0x1}
> -   vextracti32x4\t{$0x1, %g1, %0|%0, %g1, 0x1}"
> +   vextracti32x4\t{$0x1, %1, %0|%0, %1, 0x1}"
>    [(set_attr "type" "sselog1")
>     (set_attr "prefix_extra" "1")
>     (set_attr "length_immediate" "1")
> -   (set_attr "isa" "*,avx512dq,avx512f")
> -   (set_attr "prefix" "vex,evex,evex")
> +   (set_attr "isa" "*,avx512vl")
> +   (set_attr "prefix" "vex,evex")
>     (set_attr "mode" "OI")])
>
>  ;; NB: *vec_extract<mode>_0 must be placed before *vec_extracthf.
>


-- 
BR,
Hongtao