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[Bug dynamic-link/21265] _dl_runtime_resolve isn't compatible with Intel C++ __regcall calling convention


https://sourceware.org/bugzilla/show_bug.cgi?id=21265

--- Comment #15 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
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The branch, hjl/pr21265/2.24 has been created
        at  609ccf8ca804e0c65afad74fe5c6d867c3552dbb (commit)

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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=609ccf8ca804e0c65afad74fe5c6d867c3552dbb

commit 609ccf8ca804e0c65afad74fe5c6d867c3552dbb
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Mar 23 08:21:52 2017 -0700

    x86-64: Use fxsave/xsave/xsavec in _dl_runtime_resolve [BZ #21265]

    In _dl_runtime_resolve, use fxsave/xsave/xsavec to preserve all vector,
    mask and bound registers.  It simplifies _dl_runtime_resolve and supports
    different calling conventions.  ld.so code size is reduced by more than
    1 KB.  However, use fxsave/xsave/xsavec takes a little bit more cycles
    than saving and restoring vector and bound registers individually.

    Latency for _dl_runtime_resolve to lookup the function, foo, from one
    shared library plus libc.so:

                                 Before    After     Change

    Westmere (SSE)/fxsave         345      866       151%
    IvyBridge (AVX)/xsave         420      643       53%
    Haswell (AVX)/xsave           713      1252      75%
    Skylake (AVX+MPX)/xsavec      559      719       28%
    Skylake (AVX512+MPX)/xsavec   145      272       87%
    Ryzen (AVX)/xsavec            280      553       97%

    This is the worst case where portion of time spent for saving and
    restoring registers is bigger than majority of cases.  With smaller
    _dl_runtime_resolve code size, overall performance impact is negligible.

    On IvyBridge, differences in build and test time of binutils with lazy
    binding GCC and binutils are noises.  On Westmere, differences in
    bootstrap and "makc check" time of GCC 7 with lazy binding GCC and
    binutils are also noises.

        [BZ #21265]
        * sysdeps/x86/cpu-features-offsets.sym (XSAVE_STATE_SIZE_OFFSET):
        New.
        * sysdeps/x86/cpu-features.c: Include <libc-internal.h>.
        (get_common_indeces): Set xsave_state_size and
        bit_arch_XSAVEC_Usable if needed.
        (init_cpu_features): Remove bit_arch_Use_dl_runtime_resolve_slow
        and bit_arch_Use_dl_runtime_resolve_opt.
        * sysdeps/x86/cpu-features.h (bit_arch_Use_dl_runtime_resolve_opt):
        Removed.
        (bit_arch_Use_dl_runtime_resolve_slow): Likewise.
        (bit_arch_Prefer_No_AVX512): Updated.
        (bit_arch_MathVec_Prefer_No_AVX512): Likewise.
        (bit_arch_XSAVEC_Usable): New.
        (STATE_SAVE_OFFSET): Likewise.
        (STATE_SAVE_MASK): Likewise.
        [__ASSEMBLER__]: Include <cpu-features-offsets.h>.
        (cpu_features): Add xsave_state_size.
        (index_arch_Use_dl_runtime_resolve_opt): Removed.
        (index_arch_Use_dl_runtime_resolve_slow): Likewise.
        (index_arch_XSAVEC_Usable): New.
        * sysdeps/x86_64/dl-machine.h (elf_machine_runtime_setup):
        Replace _dl_runtime_resolve_sse, _dl_runtime_resolve_avx,
        _dl_runtime_resolve_avx_slow, _dl_runtime_resolve_avx_opt,
        _dl_runtime_resolve_avx512 and _dl_runtime_resolve_avx512_opt
        with _dl_runtime_resolve_fxsave, _dl_runtime_resolve_xsave and
        _dl_runtime_resolve_xsavec.
        * sysdeps/x86_64/dl-trampoline.S (DL_RUNTIME_UNALIGNED_VEC_SIZE):
        Removed.
        (DL_RUNTIME_RESOLVE_REALIGN_STACK): Check STATE_SAVE_ALIGNMENT
        instead of VEC_SIZE.
        (REGISTER_SAVE_BND0): Removed.
        (REGISTER_SAVE_BND1): Likewise.
        (REGISTER_SAVE_BND3): Likewise.
        (REGISTER_SAVE_RAX): Always defined to 0.
        (VMOV): Removed.
        (_dl_runtime_resolve_avx): Likewise.
        (_dl_runtime_resolve_avx_slow): Likewise.
        (_dl_runtime_resolve_avx_opt): Likewise.
        (_dl_runtime_resolve_avx512): Likewise.
        (_dl_runtime_resolve_avx512_opt): Likewise.
        (_dl_runtime_resolve_sse): Likewise.
        (_dl_runtime_resolve_sse_vex): Likewise.
        (USE_FXSAVE): New.
        (_dl_runtime_resolve_fxsave): Likewise.
        (USE_XSAVE): Likewise.
        (_dl_runtime_resolve_xsave): Likewise.
        (USE_XSAVEC): Likewise.
        (_dl_runtime_resolve_xsavec): Likewise.
        * sysdeps/x86_64/dl-trampoline.h (_dl_runtime_resolve_avx512):
        Removed.
        (_dl_runtime_resolve_avx512_opt): Likewise.
        (_dl_runtime_resolve_avx): Likewise.
        (_dl_runtime_resolve_avx_opt): Likewise.
        (_dl_runtime_resolve_sse): Likewise.
        (_dl_runtime_resolve_sse_vex): Likewise.
        (_dl_runtime_resolve_fxsave): New.
        (_dl_runtime_resolve_xsave): Likewise.
        (_dl_runtime_resolve_xsavec): Likewise.

    (cherry picked from commit b52b0d793dcb226ecb0ecca1e672ca265973233c)

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