Compiling on new intel AVX512 machines with magic-layout

[C. Maas]

Hi,

when compiling on new intel machines with avx512, gcc, the switch --enable-magic-layout and without --enable-openmp, i get a lot of the following errors in the file shtns_fly.c :

In file included from sht_fly.c:32:0:
SHT/SHst_to_spat_fly.c: In function ‘SHsphtor_to_spat_fly1_l’:
SHT/SHst_to_spat_fly.c:157:5: warning: implicit declaration of function ‘S2D_STORE_4MAGIC’; did you mean ‘_OLD_STDIO_MAGIC’? [-Wimplicit-function-declaration]
     S2D_STORE_4MAGIC(BtF, j+k, te[j], to[j])
     ^~~~~~~~~~~~~~~~
     _OLD_STDIO_MAGIC
SHT/SHst_to_spat_fly.c:158:5: error: expected ‘;’ before ‘S2D_STORE_4MAGIC’
     S2D_STORE_4MAGIC(BpF, j+k, pe[j], po[j])
     ^~~~~~~~~~~~~~~~
SHT/SHst_to_spat_fly.c:336:5: warning: implicit declaration of function ‘S2D_CSTORE_4MAGIC’; did you mean ‘S2D_CSTORE2’? [-Wimplicit-function-declaration]
     S2D_CSTORE_4MAGIC(BtF, k+j, ter[j], tor[j], tei[j], toi[j])
     ^~~~~~~~~~~~~~~~~
     S2D_CSTORE2
SHT/SHst_to_spat_fly.c:337:5: error: expected ‘;’ before ‘S2D_CSTORE_4MAGIC’
     S2D_CSTORE_4MAGIC(BpF, k+j, per[j], por[j], pei[j], poi[j])
     ^~~~~~~~~~~~~~~~~
SHT/SHst_to_spat_fly.c: In function ‘SHsphtor_m_to_spat_fly1_l’:
SHT/SHst_to_spat_fly.c:497:5: warning: implicit declaration of function ‘S2D_CSTORE2_4MAGIC’; did you mean ‘S2D_CSTORE2’? [-Wimplicit-function-declaration]
     S2D_CSTORE2_4MAGIC(BtF, k+j, te[j], to[j], vall(0), vall(0))
     ^~~~~~~~~~~~~~~~~~
     S2D_CSTORE2
SHT/SHst_to_spat_fly.c:498:5: error: expected ‘;’ before ‘S2D_CSTORE2_4MAGIC’
     S2D_CSTORE2_4MAGIC(BpF, k+j, pe[j], po[j], vall(0), vall(0))
     ^~~~~~~~~~~~~~~~~~
SHT/SHst_to_spat_fly.c:650:5: error: expected ‘;’ before ‘S2D_CSTORE2_4MAGIC’
     S2D_CSTORE2_4MAGIC(BpF, k+j, per[j], por[j], pei[j], poi[j])
     ^~~~~~~~~~~~~~~~~~

If I replace "-march=skylake-avx512" with "-march=skylake" compilation finishes successfully. Tested with GCC versions 6.4.0, 7.3.0 und 8.1.1 and shtns 3.1 and 3.01

Could you please look into this issue.

Thank you very much for your help.

[Nathanaël Schaeffer]

Indeed, there is some missing explicit AVX512 vectorization in the non-openmp code path for magic layout. Writing those explicit vectorization requires a bit of work. I have plans to merge all code paths to avoid these issues in the future, but this requires some substantial work too.

As an immediate workaround, I suggest the following: 1) configure with openmp enabled:

./configure  --enable-magic --enable-openmp

2) remove the -fopenmp switch from the Makefile

3) compile to get a non-openmp library that uses avx512 together with the magic-layout.

[Nathanaël Schaeffer]

fixed in earlier versions