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[Bug c/63450] Optimizing -O3 generates rep ret on an almost empty function
- From: "andi-gcc at firstfloor dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 03 Oct 2014 14:29:05 +0000
- Subject: [Bug c/63450] Optimizing -O3 generates rep ret on an almost empty function
- Auto-submitted: auto-generated
- References: <bug-63450-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63450
Andi Kleen <andi-gcc at firstfloor dot org> changed:
What |Removed |Added
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CC| |andi-gcc at firstfloor dot org
--- Comment #2 from Andi Kleen <andi-gcc at firstfloor dot org> ---
This is a feature in -mtune=generic because it helps branch prediction in some
older AMD CPUs. If you're optimizing for Atom you'll get even more padding due
to other reasons. Optimizing e.g. for nehalem should avoid it.