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On Thu, Oct 08, 2020 at 11:57:52AM +0000, Jonathan Yong wrote: |
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> I am getting AVX2 related compile errors in 32bit media-libs/opencv-4.4.0, |
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> there are some internet text mentioning not all AVX2 instructions are |
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> supported on 32bit x86. |
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> |
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> For now, I have set -abi_x86_32 since I don't need it now. |
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> |
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> Any plans to support ABI specific USE masking/setting? |
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Do you mean that you want to install the 32-bit and 64-bit version of a package, |
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enabling one set of flags on one, and another set on the other? |
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The problem you will face is that the CPU_FLAGS_X86 option, which allows you to |
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disable AVX(2) instructions, amongst many other processor extensions [1], |
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applies to both x86 and amd64 architectures, and from reading the according wiki |
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page [2], I don't think it's possible to discriminate between those two; it is |
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the responsibility of the package to test whether a particular AVX function |
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should be employed or not. |
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Can you post the output of `cpuid2cpuflags` (from app-portage/cpuid2cpuflags)? |
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If this list includes "avx2", and the compilation is still failing, this is a |
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BUG and should be reported as such. I think it's known to the Gentoo community |
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already, although it seems to be an issue with upstream [3]. Analogous issues |
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exist in other packages [4]. |
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The problem in upstream is probably caused by this call to _mm256_extract_epi64 |
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[5], introduced quite a while ago (the nature of this function, being exclusive |
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to 64-bit processors, was even noted in the commit message [6]). |
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It will probably be fixed soon. No need to worry since you don't need the 32-bit |
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binary interface anyway. |
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[1] https://gitweb.gentoo.org/repo/gentoo.git/plain/profiles/desc/cpu_flags_x86.desc |
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[2] https://wiki.gentoo.org/wiki/CPU_FLAGS_X86#Configuration |
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[3] https://bugs.gentoo.org/747163 |
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[4] https://github.com/pytorch/pytorch/issues/17901 |
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[5] https://github.com/opencv/opencv/blame/152e6476d9a270e6ce35d3f1b200a303654e576e/modules/core/include/opencv2/core/hal/intrin_avx.hpp#L130 |
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[6] https://github.com/opencv/opencv/commit/75315fb297a010153d3acab8111ebb87d909cdcf |
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-- |
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|
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Ashley Dixon |
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suugaku.co.uk |
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2A9A 4117 |
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DA96 D18A |
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8A7B B0D2 |
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A30E BF25 |
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F290 A8AA |
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