Re: [PATCH][AArch32]: Correct sdot RTL on aarch32

[Christophe Lyon via Gcc-patches]

Hi Tamar,


On Tue, May 25, 2021 at 5:41 PM Tamar Christina via Gcc-patches <
gcc-patches@gcc.gnu.org> wrote:

> Hi All,
>
> The RTL Generated from <sup>dot_prod<vsi2qi> is invalid as operand3 cannot
> be
> written to, it's a normal input.  For the expand it's just another operand
> but the caller does not expect it to be written to.
>
> Bootstrapped Regtested on arm-none-linux-gnueabihf and no issues.
>
> Ok for master? and backport to GCC 11, 10, 9?
>
> Thanks,
> Tamar
>
> gcc/ChangeLog:
>
>         * config/arm/neon.md (<sup>dot_prod<vsi2qi>): Drop statements.
>
> --- inline copy of patch --
> diff --git a/gcc/config/arm/neon.md b/gcc/config/arm/neon.md
> index
> 61d81646475ce3bf62ece2cec2faf0c1fe978ec1..9602e9993aeebf4ec620d105fd20f64498a3b851
> 100644
> --- a/gcc/config/arm/neon.md
> +++ b/gcc/config/arm/neon.md
> @@ -3067,13 +3067,7 @@ (define_expand "<sup>dot_prod<vsi2qi>"
>                      DOTPROD)
>                     (match_operand:VCVTI 3 "register_operand")))]
>    "TARGET_DOTPROD"
> -{
> -  emit_insn (
> -    gen_neon_<sup>dot<vsi2qi> (operands[3], operands[3], operands[1],
> -                                operands[2]));
> -  emit_insn (gen_rtx_SET (operands[0], operands[3]));
> -  DONE;
> -})
> +)
>
>  ;; Auto-vectorizer pattern for usdot
>  (define_expand "usdot_prod<vsi2qi>"
>
>
This patch is causing ICEs on arm-eabi (and probably arm-linux-gnueabi but
trunk build is currently broken):

 FAIL: gcc.target/arm/simd/vect-dot-s8.c (internal compiler error)
FAIL: gcc.target/arm/simd/vect-dot-s8.c (test for excess errors)
Excess errors:
/gcc/testsuite/gcc.target/arm/simd/vect-dot-qi.h:15:1: error:
unrecognizable insn:
(insn 29 28 30 5 (set (reg:V4SI 132 [ vect_patt_31.15 ])
        (plus:V4SI (unspec:V4SI [
                    (reg:V16QI 182)
                    (reg:V16QI 183)
                ] UNSPEC_DOT_S)
            (reg:V4SI 184))) -1
     (nil))
during RTL pass: vregs
/gcc/testsuite/gcc.target/arm/simd/vect-dot-qi.h:15:1: internal compiler
error: in extract_insn, at recog.c:2769
0x5fc656 _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        /gcc/rtl-error.c:108
0x5fc672 _fatal_insn_not_found(rtx_def const*, char const*, int, char
const*)
        /gcc/rtl-error.c:116
0xcbbe07 extract_insn(rtx_insn*)
        /gcc/recog.c:2769
0x9e2e95 instantiate_virtual_regs_in_insn
        /gcc/function.c:1611
0x9e2e95 instantiate_virtual_regs
        /gcc/function.c:1985
0x9e2e95 execute
        /gcc/function.c:2034

Can you check?

Thanks,

Christophe