[PATCH] x86: Require MMX for __builtin_ia32_maskmovq

[Uros Bizjak]

> Since "MASKMOVQ mm1, mm2" is an SSE instruction which requires MMX and
> MMX/SSE ISAs are handled separately, make __builtin_ia32_maskmovq require
> MMX instead of SSE.
>
> gcc/
>
> PR target/97140
> * config/i386/i386-expand.c (ix86_expand_builtin): Require MMX
> for __builtin_ia32_maskmovq.
>
> gcc/testsuite/
>
> PR target/97140
> * gcc.target/i386/pr97140.c: New test.

TBH, from your submission, it was not clear to me, what did you want
to achieve with the patch. Replies to your own patches were kind of
contradicting [1] and confuse the reader even more.

It took me a good chunk of time to figure out what the patch does, the
git comment was also of no use. I don't think a review should take
that long for a simple one-liner.

So, to save you and others from a year of futile pinging: Please send
a clean submission of a patch, and clearly state that MASKMOVQ can't
be easily emulated with SSE instructions, so it is emulated at the
intrinsic level. The *builtin* that corresponds to MASKMOVQ
instruction requires TARGET_MMX, otherwise MMX registers can't be
instantiated ... etc, etc.

All this while having in mind that __builtin_ia32_* builtins are not
part of a published interface.

And please Cc me on patches.

[1] https://gcc.gnu.org/pipermail/gcc-patches/2020-September/554385.html

Uros.