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| author | Andy Polyakov <appro@openssl.org> | 2016-12-14 13:33:40 +0100 |
|---|---|---|
| committer | Andy Polyakov <appro@openssl.org> | 2016-12-15 17:57:38 +0100 |
| commit | 569204be9095e6c706d887dd0359ca6e309db026 (patch) | |
| tree | 0322e174b8983ea557c2331785538f9221f98878 | |
| parent | 2b40699082d1e5d0e94811542c4f0633ab2d5989 (diff) | |
| download | openssl-569204be9095e6c706d887dd0359ca6e309db026.tar.gz | |
man3/OPENSSL_ia32cap.pod: clarify AVX512 support in clang context.
Reviewed-by: Richard Levitte <levitte@openssl.org>
| -rw-r--r-- | doc/man3/OPENSSL_ia32cap.pod | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/doc/man3/OPENSSL_ia32cap.pod b/doc/man3/OPENSSL_ia32cap.pod index 60dd96484c..5071659074 100644 --- a/doc/man3/OPENSSL_ia32cap.pod +++ b/doc/man3/OPENSSL_ia32cap.pod @@ -101,6 +101,9 @@ and RORX; =item bit #64+19 denoting availability of ADCX and ADOX instructions; +=item bit #64+21 denoting availability of VPMADD52[LH]UQ instructions, +a.k.a. AVX512IFMA extension; + =item bit #64+29 denoting availability of SHA extension; =item bit #64+30 denoting availability of AVX512BW extension; @@ -125,7 +128,23 @@ requirements are summarized in below table: AVX | 2.19 | 2.09 | 3.0 AVX2 | 2.22 | 2.10 | 3.1 ADCX/ADOX | 2.23 | 2.10 | 3.3 - AVX512 | 2.25 | 2.11.8 | 3.6 + AVX512 | 2.25 | 2.11.8 | see NOTES + AVX512IFMA | 2.26 | 2.11.8 | see NOTES + +=head1 NOTES + +Even though AVX512 support was implemented in llvm 3.6, compilation of +assembly modules apparently requires explicit -march flag. But then +compiler generates processor-specific code, which in turn contradicts +the mere idea of run-time switch execution facilitated by the variable +in question. Till the limitation is lifted, it's possible to work around +the problem by making build procedure use following script: + + #!/bin/sh + exec clang -no-integrated-as "$@" + +instead of real clang. In which case it doesn't matter which clang +version is used, as it is GNU assembler version that will be checked. =head1 COPYRIGHT |