Fixes for SSE detection and propagation #24
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Please hold off on merging... this is broken. |
On a machine without SSE4.1 the HAVE_SSE flag would still be set. Because CFLAGS is set to include -msse4.2, the compiler happily generates SSE 4.2 instructions. Running any resulting SSE-enabled binary would then result in an illegal instruction error. The HAVE_SSE check now checks for the presence of one of the SSE 4.1 instructions that is used in the SSE enabled convolutional decoder. The check must run with -march=native to ensure it checks against the host machine capabilities. The HAVE_SSE definition is now propagated to downstream targets that depend on libcorrect. This means they can now ifdef on HAVE_SSE to decide whether or not to include libcorrect's SSE specific header. Confirmed that the HAVE_SSE check now fails on an old machine without SSE 4.1 (but with SSE 3 and SSSE 3).
pietern
changed the title
pietern
changed the title
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No longer broken :-) |
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thank you, this is great. i have also considered putting runtime checks for SSE into the code itself, and i do think that's still worth doing, but i'm glad to merge this now. |
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Thanks @brian-armstrong! |
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On a machine without SSE4.1 the HAVE_SSE flag would still be set.
Because CFLAGS is set to include -msse4.2, the compiler happily
generates SSE 4.2 instructions. Running any resulting SSE-enabled
binary would then result in an illegal instruction error.
The HAVE_SSE check now checks for the presence of one of the SSE 4.1
instructions that is used in the SSE enabled convolutional decoder.
The check must run with -march=native to ensure it checks against the
host machine capabilities.
The HAVE_SSE definition is now propagated to downstream targets that
depend on libcorrect. This means they can now ifdef on HAVE_SSE to
decide whether or not to include libcorrect's SSE specific header.
Confirmed that the HAVE_SSE check now fails on an old machine without
SSE 4.1 (but with SSE 3 and SSSE 3).