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Re: "float complex" arithmetic performance much slower than expected
- From: Alexander Monakov <amonakov at ispras dot ru>
- To: Michele Martone <michele dot martone at ipp dot mpg dot de>
- Cc: gcc-help at gcc dot gnu dot org
- Date: Wed, 6 Mar 2013 20:49:53 +0400 (MSK)
- Subject: Re: "float complex" arithmetic performance much slower than expected
- References: <20130306163749.GJ17853@localhost>
On Wed, 6 Mar 2013, Michele Martone wrote:
> . CFLAGS for gcc:
> "-O3 -pipe -march=native -mtune=native -mavx -std=c99 -fno-unroll-loops"
> . CFLAGS for icc: "-O3 -xAVX -restrict -unroll=0"
This makes a comparison "unfair" since the two compilers use different
optimization restrictions for floating-point operations by default (GCC is
conservative, and thus more restricted in optimizations). See the
documentation for -ffast-math GCC option, and floating-point flags in the ICC
help (e.g. options -fp-model and -mp).
Alexander