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[Bug tree-optimization/70479] FMA is not reassociated causing x2 slowdown vs. ICC
- From: "kyukhin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 31 Mar 2016 13:25:49 +0000
- Subject: [Bug tree-optimization/70479] FMA is not reassociated causing x2 slowdown vs. ICC
- Auto-submitted: auto-generated
- References: <bug-70479-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70479
--- Comment #1 from Kirill Yukhin <kyukhin at gcc dot gnu.org> ---
(In reply to Kirill Yukhin from comment #0)
> Compile:
> GCC: g++ -march=haswell -Ofast -flto -fopenmp-simd -fpermissive m.cpp -o
> m.gcc
> ICC: icpc -O3 -ipo -fpermissive -xAVX2 -qopenmp m.cpp -o m.icc
Correct compile commands (original are for Haswell)
GCC: g++ -march=knl -Ofast -flto -fopenmp-simd -fpermissive m.cpp -o m.gcc
ICC: icpc -O3 -ipo -fpermissive -xMIC-AVX512 -qopenmp m.cpp -o m.icc