[Bug target/85100] __builtin_cpu_supports avx does not verify OS supports it

[hjl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85100

--- Comment #11 from hjl at gcc dot gnu.org <hjl at gcc dot gnu.org> ---
Author: hjl
Date: Mon Apr  2 12:09:48 2018
New Revision: 259007

URL: https://gcc.gnu.org/viewcvs?rev=259007&root=gcc&view=rev
Log:
i386: Enable AVX/AVX512 features only if supported by OSXSAVE

Enable AVX and AVX512 features only if their states are supported by
OSXSAVE.

        Backport from mainline
        PR target/85100
        * config/i386/cpuinfo.c (XCR_XFEATURE_ENABLED_MASK): New.
        (XSTATE_FP): Likewise.
        (XSTATE_SSE): Likewise.
        (XSTATE_YMM): Likewise.
        (XSTATE_OPMASK): Likewise.
        (XSTATE_ZMM): Likewise.
        (XSTATE_HI_ZMM): Likewise.
        (XCR_AVX_ENABLED_MASK): Likewise.
        (XCR_AVX512F_ENABLED_MASK): Likewise.
        (get_available_features): Enable AVX and AVX512 features only
        if their states are supported by OSXSAVE.

Modified:
    branches/gcc-6-branch/libgcc/ChangeLog
    branches/gcc-6-branch/libgcc/config/i386/cpuinfo.c