https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94962
--- Comment #10 from CVS Commits ---
The master branch has been updated by hongtao Liu :
https://gcc.gnu.org/g:9c9cf4f087f28dc3bf8dfa769380b3b58728a0f7
commit r13-2845-g9c9cf4f087f28dc3bf8dfa769380b3b58728a0f7
Author: Hu, Lin1
Date: Mon Sep
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94962
--- Comment #9 from Hongtao.liu ---
Fixed in trunk.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94962
--- Comment #8 from CVS Commits ---
The master branch has been updated by hongtao Liu :
https://gcc.gnu.org/g:a282f086ef26d90e9785e992cd09a0d118b24695
commit r13-2804-ga282f086ef26d90e9785e992cd09a0d118b24695
Author: Hu, Lin1
Date: Tue Sep
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94962
--- Comment #7 from Nemo ---
(In reply to Hongtao.liu from comment #6)
>
> vmovdqa xmm0, xmm0 is not redundant here, it would clear up 128-256 bit
> which is the meaning of `zext`.
No, it is redundant because "vpcmpeqd xmm0, xmm0, xmm0" already
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94962
--- Comment #6 from Hongtao.liu ---
(In reply to Nemo from comment #5)
> (In reply to Jakub Jelinek from comment #2)
>
> I would be happy if GCC could just emit optimal code (single vcmpeqd
> instruction) for this useful constant:
>
>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94962
--- Comment #5 from Nemo ---
(In reply to Jakub Jelinek from comment #2)
I would be happy if GCC could just emit optimal code (single vcmpeqd
instruction) for this useful constant:
_mm256_set_m128i(_mm_setzero_si128(), _mm_set1_epi8(-1))
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94962
--- Comment #4 from Hongtao.liu ---
(In reply to Jakub Jelinek from comment #2)
> But such an instruction isn't always redundant, it really depends on what
> the previous setter of the register did, whether the upper 128 bit of the
> 256-bit
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94962
--- Comment #3 from Hongtao.liu ---
You're right, from intel SDM:
VEX.128 encoded version: Bits (MAXVL-1:128) of the destination register are
zeroed.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94962
Jakub Jelinek changed:
What|Removed |Added
CC||jakub at gcc dot gnu.org
--- Comment #2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94962
Hongtao.liu changed:
What|Removed |Added
CC||crazylht at gmail dot com
--- Comment #1
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