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