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[Bug tree-optimization/57858] AVX2: ymm used for div, not for sqrt
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 10 Jul 2013 06:37:09 +0000
- Subject: [Bug tree-optimization/57858] AVX2: ymm used for div, not for sqrt
- Auto-submitted: auto-generated
- References: <bug-57858-4 at http dot gcc dot gnu dot org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57858
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Actually, it isn't vectorized at all, because PRE attempts to be smart, figures
out that for the first iteration of the loop it can avoid computing the sqrt
because the result will be one, and moves thus the sqrt call into the latch,
but we can't vectorize any loops that have non-empty latches.
So, either the vectorizer would need to undo this transformation, or PRE not do
it at all, or arrange for it to be done only after vectorizations. Richard,
any thoughts on this?