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7e681561a3
When compiled with -O3 and AVX, GCC 8 and 9 optimize some loops in sysdeps/ieee754/dbl-64/branred.c with 256-bit vector instructions, which leads to store forward stall: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90579 There is no easy fix in compiler. This patch limits vector width to 128 bits to work around this issue. It improves performance of sin and cos by more than 40% on Skylake compiled with -O3 -march=skylake. Tested with GCC 7/8/9 on x86-64. [BZ #24603] * sysdeps/x86_64/configure.ac: Check if -mprefer-vector-width=128 works. * sysdeps/x86_64/configure: Regenerated. * sysdeps/x86_64/fpu/Makefile (CFLAGS-branred.c): New. Set to -mprefer-vector-width=128 if supported.
87 lines
2.5 KiB
Plaintext
87 lines
2.5 KiB
Plaintext
GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
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# Local configure fragment for sysdeps/x86_64.
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dnl Check if asm supports AVX512DQ.
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AC_CACHE_CHECK(for AVX512DQ support in assembler, libc_cv_asm_avx512dq, [dnl
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cat > conftest.s <<\EOF
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vandpd (%rax), %zmm6, %zmm1
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EOF
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if AC_TRY_COMMAND(${CC-cc} -c $ASFLAGS conftest.s 1>&AS_MESSAGE_LOG_FD); then
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libc_cv_asm_avx512dq=yes
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else
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libc_cv_asm_avx512dq=no
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fi
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rm -f conftest*])
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if test $libc_cv_asm_avx512dq = yes; then
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AC_DEFINE(HAVE_AVX512DQ_ASM_SUPPORT)
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fi
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dnl Check if -mavx512f works.
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AC_CACHE_CHECK(for AVX512 support, libc_cv_cc_avx512, [dnl
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LIBC_TRY_CC_OPTION([-mavx512f], [libc_cv_cc_avx512=$libc_cv_asm_avx512dq], [libc_cv_cc_avx512=no])
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])
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if test $libc_cv_cc_avx512 = yes; then
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AC_DEFINE(HAVE_AVX512_SUPPORT)
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fi
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LIBC_CONFIG_VAR([config-cflags-avx512], [$libc_cv_cc_avx512])
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dnl Check if -mprefer-vector-width=128 works.
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AC_CACHE_CHECK(-mprefer-vector-width=128, libc_cv_cc_mprefer_vector_width, [dnl
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LIBC_TRY_CC_OPTION([-mprefer-vector-width=128],
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[libc_cv_cc_mprefer_vector_width=yes],
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[libc_cv_cc_mprefer_vector_width=no])
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])
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LIBC_CONFIG_VAR([config-cflags-mprefer-vector-width],
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[$libc_cv_cc_mprefer_vector_width])
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dnl Check whether asm supports Intel MPX
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AC_CACHE_CHECK(for Intel MPX support, libc_cv_asm_mpx, [dnl
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cat > conftest.s <<\EOF
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bndmov %bnd0,(%rsp)
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EOF
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if AC_TRY_COMMAND(${CC-cc} -c $ASFLAGS conftest.s 1>&AS_MESSAGE_LOG_FD); then
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libc_cv_asm_mpx=yes
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else
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libc_cv_asm_mpx=no
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fi
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rm -f conftest*])
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if test $libc_cv_asm_mpx = yes; then
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AC_DEFINE(HAVE_MPX_SUPPORT)
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fi
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if test x"$build_mathvec" = xnotset; then
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build_mathvec=yes
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fi
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dnl Check if linker supports static PIE with the fix for
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dnl
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dnl https://sourceware.org/bugzilla/show_bug.cgi?id=21782
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dnl
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if test "$static_pie" = yes; then
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AC_CACHE_CHECK(for linker static PIE support, libc_cv_ld_static_pie, [dnl
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cat > conftest.s <<\EOF
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.text
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.global _start
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.weak foo
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_start:
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leaq foo(%rip), %rax
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EOF
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libc_cv_pie_option="-Wl,-pie"
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if AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostartfiles -nostdlib $no_ssp $libc_cv_pie_option -o conftest conftest.s 1>&AS_MESSAGE_LOG_FD); then
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libc_cv_ld_static_pie=yes
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else
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libc_cv_ld_static_pie=no
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fi
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rm -f conftest*])
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if test "$libc_cv_ld_static_pie" != yes; then
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AC_MSG_ERROR([linker support for static PIE needed])
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fi
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fi
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dnl It is always possible to access static and hidden symbols in an
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dnl position independent way.
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AC_DEFINE(PI_STATIC_AND_HIDDEN)
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test -n "$critic_missing" && AC_MSG_ERROR([
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*** $critic_missing])
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