https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108401
Hongtao.liu <crazylht at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |crazylht at gmail dot com
--- Comment #3 from Hongtao.liu <crazylht at gmail dot com> ---
> and gcc 12 generates a worse code:
>
> movabs rax, 71777214294589695
> vmovq xmm1, rax
> vpbroadcastq ymm0, xmm1
> ret
>
It's on purpose by edafb35bdadf309ebb9d1eddc5549f9e1ad49c09 since
microbenchmark shows moving from imm is faster than memory.
> In all cases, the compiler flags are: -O3 -march=haswell
>
> Code on godbolt.org: https://gcc.godbolt.org/z/sfT787PY9
>
> I think the compiler should follow the code in intrinsics more closely since
> despite the apparent equivalence, the choice of instructions can have
> performance implications. The original code that is written by the developer
> is better anyway, so it's not clear why the compiler is being so creative in
> this case.
