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[Bug tree-optimization/82666] [7/8 regression]: sum += (x>128 ? x : 0) puts the cmov on the critical path (at -O2)
- From: "marxin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 23 Oct 2017 07:54:01 +0000
- Subject: [Bug tree-optimization/82666] [7/8 regression]: sum += (x>128 ? x : 0) puts the cmov on the critical path (at -O2)
- Auto-submitted: auto-generated
- References: <bug-82666-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82666
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |marxin at gcc dot gnu.org
--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Created attachment 42437
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42437&action=edit
Reproducer (micro benchmark)
Confirmed, I'm attaching micro-benchmark that I run on my Haswell machine.
In time between GCC 6.x and current trunk we first improved performance in
r239414 from 1.392704s -> 1.228814s. Then we significantly regressed in r242832
from 1.209454s -> 1.929302s.