[PATCH] D29874: [X86] Generate VZEROUPPER for Skylake-avx512

[Amjad Aboud via Phabricator via llvm-commits]

aaboud added inline comments.


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Comment at: lib/Target/X86/X86VZeroUpper.cpp:225
 
     // The VZEROUPPER instruction resets the upper 128 bits of all AVX
     // registers. In addition, the processor changes back to Clean state, after
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aaboud wrote:
> craig.topper wrote:
> > aaboud wrote:
> > > craig.topper wrote:
> > > > This comments is stale with ZMM. It's not upper 128 bits.
> > > Actually, this is what it does. even for the ZMM registers it reset the upper 128bits of the YMM corresponding register. Is not it?
> > > 
> > > The important behavior is the next sentence, which emphasize that processor changes back to Clean state.
> > Doesn't it clear the upper 384 bits of ZMM? The comment itself doesn't say YMM. It just says "AVX registers".
> I am fine with rephrasing the comment, though AVX registers does not include any ZMM, just YMM.
> Do you think I should replace YMM with ZMM?
> I am fine with rephrasing the comment, though AVX registers does not include any ZMM, just YMM.
> Do you think I should replace YMM with ZMM?

I meant to say: Do you think I should replace AVX with YMM (or YMM0-16)?


https://reviews.llvm.org/D29874