[gmx-developers] Wrong compiler flag when using the Intel compiler for Skylake CPUs

[Erik Lindahl]

Hi Daniel,

Thanks for spotting that - it's now fixed in
https://gerrit.gromacs.org/#/c/6568/ .

Cheers,

Erik

On Sat, Apr 1, 2017 at 7:36 AM, Daniel Tameling <tamelingdaniel at gmail.com>
wrote:

> Dear all,
>
> I recently built GROMACS 2016.1 for the Skylake architecture.
> However, the executable crashed when I trid to run it.
> The reason for this was that the code was compiled with -xMIC-AVX512,
> which generates AVX512 instructions for the Knights Landing architecture,
> which are partly incompatible with the AVX512 instruction set for Skylakes.
>
> The reason for this compiler flag to be used is the following code
> in cmake/gmxManageSimd.cmake
>
> elseif(GMX_SIMD STREQUAL "AVX_512")
>
>    ...
>
>    "-xMIC-AVX512" "-mavx512f -mfma" "-mavx512f" "/arch:AVX" "-hgnu") # no AVX_512F flags known for MSVC yet
>
>
> I checked the GROMACS repository, and this code seems still to be present.
>
> To generate correct code for Skylakes, the -xMIC-AVX512 should be replaced by -xCORE-AVX512.
>
>
> Best regards,
>
> Daniel
>
>
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-- 
--
Erik Lindahl <erik.lindahl at gmail.com>
Professor of Biophysics, Dept. Biochemistry & Biophysics, Stockholm
University
Science for Life Laboratory, Box 1031, 17121 Solna, Sweden
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