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Avoid generating vzeroupper instruction
- From: Gunther Piez <gupiez at googlemail dot com>
- To: gcc-help at gcc dot gnu dot org
- Date: Wed, 02 May 2012 15:44:09 +0200
- Subject: Avoid generating vzeroupper instruction
Hello,
is there a way to tell gcc to not emit the `vzeroupper` instruction
while using -march=corei7avx? I do realize that this instruction is
neccessary if legacy 128 bit SSE instructions are intermixed with AVX
128/256 bit code, like calling a libc function which makes use of SSE in
a non-AVX glibc or the other way around.
But in a pure AVX code environment I noticed it actually does hurt
performance. So how can I tell gcc to not emit vzeroupper while
generating AVX instructions?
- Gunther