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This commit is contained in:
Martin Reinecke 2019-01-21 11:14:19 +01:00
parent 90d2444bf1
commit e231a0e184
1 changed files with 13 additions and 13 deletions
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26
COMPILE
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@ -28,14 +28,14 @@ to the C99 standard, you should still be able to compile libsharp with
Runtime CPU selection with gcc
------------------------------
When using a recent gcc (6.0 and newer) on an x86_64 platform, the build
machinery will compile the time-critical functions for several different
architectures (SSE2, AVX, AVX2, FMA3, FMA4, AVX512F), and the appropriate
implementation will be selected at runtime.
This only happens if you do _not_ explicitly specify a target architecture via
the compiler flags. I.e., please do _not_ specify "-march=native" or
"-mtarget=avx" or similar if you want a portable binary that will run
efficiently on different x86_64 CPUs.
When using a recent gcc (6.0 and newer) or a recent clang (successfully tested
with versions 6 and 7) on an x86_64 platform, the build machinery can compile
the time-critical functions for several different architectures (SSE2, AVX,
AVX2, FMA3, FMA4, AVX512F), and the appropriate implementation will be selected
at runtime.
This is enabled by passing "-DMULTIARCH" as part of the CFLAGS.
If this is enabled, please do _not_ specify "-march=native" or
"-mtarget=avx" or similar!
If you are compiling libsharp for a particular target CPU only, or if you are
using a different compiler, however, "-march-native" should be used. The
resulting binary will most likely not run on other computers, though.
@ -65,16 +65,16 @@ Example configure invocations
=============================
GCC, OpenMP, portable binary:
CFLAGS="-std=c99 -O3 -ffast-math -fopenmp" ./configure
CFLAGS="-DMULTIARCH -std=c99 -O3 -ffast-math -fopenmp" ./configure
GCC, no OpenMP, portable binary:
CFLAGS="-std=c99 -O3 -ffast-math" ./configure
CFLAGS="-DMULTIARCH -std=c99 -O3 -ffast-math" ./configure
Clang, OpenMP, nonportable binary:
CC=clang CFLAGS="-std=c99 -O3 -march=native -ffast-math -fopenmp" ./configure
Clang, OpenMP, portable binary:
CC=clang CFLAGS="-DMULTIARCH -std=c99 -O3 -ffast-math -fopenmp" ./configure
Intel C compiler, OpenMP, nonportable binary:
CC=icc CFLAGS="-std=c99 -O3 -march=native -ffast-math -fopenmp" ./configure
CC=icc CFLAGS="-std=c99 -O3 -march=native -ffast-math -fopenmp -D__PURE_INTEL_C99_HEADERS__" ./configure
MPI support, nonportable binary:
CC=mpicc CFLAGS="-DUSE_MPI -std=c99 -O3 -march=native -ffast-math" ./configure