On Fri, Jun 25, 2021 at 5:39 AM H.J. Lu <hjl.to...@gmail.com> wrote: > > On Fri, Jun 25, 2021 at 12:50 AM Uros Bizjak <ubiz...@gmail.com> wrote: > > > > On Fri, Jun 25, 2021 at 4:51 AM Hongtao Liu <crazy...@gmail.com> wrote: > > > > > > On Fri, Jun 25, 2021 at 12:13 AM Uros Bizjak via Gcc-patches > > > <gcc-patches@gcc.gnu.org> wrote: > > > > > > > > On Thu, Jun 24, 2021 at 2:12 PM H.J. Lu <hjl.to...@gmail.com> wrote: > > > > > > > > > > CPUID functions are used to detect CPU features. If vector ISAs > > > > > are enabled, compiler is free to use them in these functions. Add > > > > > __attribute__ ((target("general-regs-only"))) to CPUID functions > > > > > to avoid vector instructions. > > > > > > > > These functions are intended to be inlined, so how does target > > > > attribute affect inlining? > > > I guess w/ -O0. they may not be inlined, that's why H.J adds those > > > attributes to those functions. > > > > The problem is not with these functions, but with surrounding checks > > for cpuid features. These checks are implemented with logic > > instructions, and nothing prevents RA from allocating mask registers, > > and consequently mask insn is emitted. Regarding mentioned functions, > > cpuid insn pattern has four GPR single-reg constraints, so mask > > registers can't be allocated here. > > > > > pr96814.dump: > > > 0804aa40 <main>: > > > 804aa40: 8d 4c 24 04 lea 0x4(%esp),%ecx > > > ... > > > 804aa63: 6a 07 push $0x7 > > > 804aa65: e8 e0 e7 ff ff call 804924a <__get_cpuid_count> > > > > > > Also we need to add a target attribute to avx512f_os_support (), and > > > that would be enough to fix the AVX512 part. > > > > > > Moreover, all check functions in below files may also need to deal with: > > > adx-check.h > > > aes-avx-check.h > > > aes-check.h > > > amx-check.h > > > attr-nocf-check-1a.c > > > attr-nocf-check-3a.c > > > avx2-check.h > > > avx2-vpop-check.h > > > avx512bw-check.h > > > avx512-check.h > > > avx512dq-check.h > > > avx512er-check.h > > > avx512f-check.h > > > avx512vl-check.h > > > avx-check.h > > > bmi2-check.h > > > bmi-check.h > > > cf_check-1.c > > > cf_check-2.c > > > cf_check-3.c > > > cf_check-4.c > > > cf_check-5.c > > > f16c-check.h > > > fma4-check.h > > > fma-check.h > > > isa-check.h > > > lzcnt-check.h > > > m128-check.h > > > m256-check.h > > > m512-check.h > > > mmx-3dnow-check.h > > > mmx-check.h > > > pclmul-avx-check.h > > > pclmul-check.h > > > pr39315-check.c > > > rtm-check.h > > > sha-check.h > > > spellcheck-options-1.c > > > spellcheck-options-2.c > > > spellcheck-options-3.c > > > spellcheck-options-4.c > > > spellcheck-options-5.c > > > sse2-check.h > > > sse3-check.h > > > sse4_1-check.h > > > sse4_2-check.h > > > sse4a-check.h > > > sse-check.h > > > ssse3-check.h > > > stack-check-11.c > > > stack-check-12.c > > > stack-check-17.c > > > stack-check-18.c > > > stack-check-19.c > > > xop-check.h > > > > True, but this would just paper over the real problem. Now, it is > > expected that the user decorates the function that checks CPUID > > features with the target attribute. I'm not sure if this is OK. > > > > Uros. > > CPUID functions are used to detect CPU features. If mask instructions > are enabled, compiler is free to use them in these functions. Disable > AVX512F in AVX512 check with target pragma to avoid mask instructions. > > OK for master? >
PING: https://gcc.gnu.org/pipermail/gcc-patches/2021-June/573717.html -- H.J.