[PATCH] math: Fix x86_64 build for -Os (BZ 33367)
H.J. Lu
hjl.tools@gmail.com
Mon Sep 8 15:56:04 GMT 2025
On Mon, Sep 8, 2025 at 8:27 AM Adhemerval Zanella Netto
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 08/09/25 12:22, H.J. Lu wrote:
> > On Mon, Sep 8, 2025 at 7:26 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>
> >> On Sat, Sep 6, 2025 at 3:22 PM Adhemerval Zanella
> >> <adhemerval.zanella@linaro.org> wrote:
> >>>
> >>> The compiler might not inline the trunc function call for
> >>> USE_TRUNC_BUILTIN, which requires adding the required objects.
> >>>
> >>> Route trunc calls for the optimized modf variants to thei
> >>> ABI-compatible version. This avoids invoking the ifunc variant
> >>> for x86_64-v1 and requires fewer objects to be added.
> >>>
> >>> Checked on x86_64, x86_64-v2, x86_64-v3, and x86_64-v4. Used -O2 and
> >>> -Os options. Performed a full make check on x86_64 with both
> >>> optimizations.
> >>> ---
> >>> sysdeps/x86_64/fpu/multiarch/Makefile | 19 ++++++++++++-------
> >>> sysdeps/x86_64/fpu/multiarch/s_modf-avx.c | 5 +++++
> >>> sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c | 5 +++++
> >>> sysdeps/x86_64/fpu/multiarch/s_modf.c | 1 -
> >>> sysdeps/x86_64/fpu/multiarch/s_modff-avx.c | 5 +++++
> >>> sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c | 5 +++++
> >>> sysdeps/x86_64/fpu/multiarch/s_modff.c | 1 -
> >>> 7 files changed, 32 insertions(+), 9 deletions(-)
> >>>
> >>> diff --git a/sysdeps/x86_64/fpu/multiarch/Makefile b/sysdeps/x86_64/fpu/multiarch/Makefile
> >>> index 708b14297f..baefe8dd07 100644
> >>> --- a/sysdeps/x86_64/fpu/multiarch/Makefile
> >>> +++ b/sysdeps/x86_64/fpu/multiarch/Makefile
> >>> @@ -26,6 +26,11 @@ CFLAGS-s_sinf-fma.c = -mfma -mavx2
> >>> CFLAGS-s_cosf-fma.c = -mfma -mavx2
> >>> CFLAGS-s_sincosf-fma.c = -mfma -mavx2
> >>>
> >>> +sysdep_calls += \
> >>> + s_trunc-sse4_1 \
> >>> + s_truncf-sse4_1 \
> >>> +# sysdep_calls
> >>> +
> >>> # Check if ISA level is 2 or above.
> >>> ifeq (,$(filter $(have-x86-isa-level),$(x86-isa-level-2-or-above)))
> >>> sysdep_calls += \
> >>> @@ -36,6 +41,10 @@ endif
> >>>
> >>> # Check if ISA level is 3 or above.
> >>> ifneq (,$(filter $(have-x86-isa-level),$(x86-isa-level-3-or-above)))
> >>> +sysdep_calls += \
> >>> + s_trunc-avx \
> >>> + s_truncf-avx \
> >>> +# sysdep_calls
> >>> libm-sysdep_routines += \
> >>> s_ceil-avx \
> >>> s_ceilf-avx \
> >>> @@ -47,8 +56,6 @@ libm-sysdep_routines += \
> >>> s_rintf-avx \
> >>> s_roundeven-avx \
> >>> s_roundevenf-avx \
> >>> - s_trunc-avx \
> >>> - s_truncf-avx \
> >>> # libm-sysdep_routines
> >>> else
> >>> sysdep_calls += \
> >>> @@ -114,8 +121,6 @@ libm-sysdep_routines += \
> >>> s_tan-avx \
> >>> s_tan-fma \
> >>> s_tanh-fma \
> >>> - s_trunc-sse4_1 \
> >>> - s_truncf-sse4_1 \
> >>> # libm-sysdep_routines
> >>> ifeq ($(have-x86-isa-level),baseline)
> >>> libm-sysdep_routines += \
> >>> @@ -132,13 +137,13 @@ libm-sysdep_routines += \
> >>> s_trunc-c \
> >>> s_truncf-c \
> >>> # libm-sysdep_routines
> >>> -endif
> >>> +endif # ($(have-x86-isa-level),baseline)
> >>> +endif # (,$(filter $(have-x86-isa-level),$(x86-isa-level-3-or-above)))
> >>>
> >>> # $(sysdep_calls) functions are built both for libc and libm. While the
> >>> # libc objects have the prefix s_, the libm ones are prefixed with m_.
> >>> -sysdep_routines += $(sysdep_calls)
> >>> +sysdep_routines += $(sysdep_calls)
> >>> libm-sysdep_routines += $(sysdep_calls:s_%=m_%)
> >>> -endif
> >>>
> >>> CFLAGS-e_asin-fma4.c = -mfma4
> >>> CFLAGS-e_atan2-fma4.c = -mfma4
> >>> diff --git a/sysdeps/x86_64/fpu/multiarch/s_modf-avx.c b/sysdeps/x86_64/fpu/multiarch/s_modf-avx.c
> >>> index ab4f03db0e..25617c4fdc 100644
> >>> --- a/sysdeps/x86_64/fpu/multiarch/s_modf-avx.c
> >>> +++ b/sysdeps/x86_64/fpu/multiarch/s_modf-avx.c
> >>> @@ -1,3 +1,8 @@
> >>> +#include <sysdeps/x86/isa-level.h>
> >>> +#if MINIMUM_X86_ISA_LEVEL < SSE4_1_X86_ISA_LEVEL
> >>> +asm ("__trunc = __trunc_sse41");
> >>
> >> It looks odd for __modf_avx to call __trunc_sse41. But this is a
> >> separate issue.
> >> We do have s_truncf-avx.S, but it isn't used by default. I think we should
> >> make it available for s_modf.c and s_modf-avx.c first.
> >
> > Can we use inline functions?
>
> It might an option, and I think it simplified the Makefile requirement.
> I will update the patch with this.
>
> Do we have a way to force compiler always expand the builin
> regardless of the optimization level?
#include <math.h>
#include <x86intrin.h>
double
__trunc (double x)
{
#ifdef __AVX__
asm ("vroundsd $11, %1, %1, %0" : "=v" (x) : "v" (x));
#elif defined __SSE4_1__
asm ("roundsd $11, %1, %0" : "=x" (x) : "x" (x));
#else
x = trunc (x);
#endif
return x;
}
> >
> >>> +#endif
> >>> +
> >>> #define __modf __modf_avx
> >>>
> >>> #include <sysdeps/ieee754/dbl-64/s_modf.c>
> >>> diff --git a/sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c b/sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c
> >>> index 00aa8cd736..086499282e 100644
> >>> --- a/sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c
> >>> +++ b/sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c
> >>> @@ -1,3 +1,8 @@
> >>> +#include <sysdeps/x86/isa-level.h>
> >>> +#if MINIMUM_X86_ISA_LEVEL < SSE4_1_X86_ISA_LEVEL
> >>> +asm ("__trunc = __trunc_sse41");
> >>> +#endif
> >>> +
> >>> #define __modf __modf_sse41
> >>>
> >>> #include <sysdeps/ieee754/dbl-64/s_modf.c>
> >>> diff --git a/sysdeps/x86_64/fpu/multiarch/s_modf.c b/sysdeps/x86_64/fpu/multiarch/s_modf.c
> >>> index e365bfcef7..dc5d7931c8 100644
> >>> --- a/sysdeps/x86_64/fpu/multiarch/s_modf.c
> >>> +++ b/sysdeps/x86_64/fpu/multiarch/s_modf.c
> >>> @@ -18,7 +18,6 @@
> >>>
> >>> #include <sysdeps/x86/isa-level.h>
> >>> #if MINIMUM_X86_ISA_LEVEL < AVX_X86_ISA_LEVEL
> >>> -# define NO_MATH_REDIRECT
> >>> # include <libm-alias-double.h>
> >>>
> >>> # define modf __redirect_modf
> >>> diff --git a/sysdeps/x86_64/fpu/multiarch/s_modff-avx.c b/sysdeps/x86_64/fpu/multiarch/s_modff-avx.c
> >>> index 07cb9c1036..dd5e37b569 100644
> >>> --- a/sysdeps/x86_64/fpu/multiarch/s_modff-avx.c
> >>> +++ b/sysdeps/x86_64/fpu/multiarch/s_modff-avx.c
> >>> @@ -1,3 +1,8 @@
> >>> +#include <sysdeps/x86/isa-level.h>
> >>> +#if MINIMUM_X86_ISA_LEVEL < SSE4_1_X86_ISA_LEVEL
> >>> +asm ("__truncf = __truncf_sse41");
> >>> +#endif
> >>> +
> >>> #define __modff __modff_avx
> >>>
> >>> #include <sysdeps/ieee754/flt-32/s_modff.c>
> >>> diff --git a/sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c b/sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c
> >>> index 060c5e3979..bf73ba3517 100644
> >>> --- a/sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c
> >>> +++ b/sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c
> >>> @@ -1,3 +1,8 @@
> >>> +#include <sysdeps/x86/isa-level.h>
> >>> +#if MINIMUM_X86_ISA_LEVEL < SSE4_1_X86_ISA_LEVEL
> >>> +asm ("__truncf = __truncf_sse41");
> >>> +#endif
> >>> +
> >>> #define __modff __modff_sse41
> >>>
> >>> #include <sysdeps/ieee754/flt-32/s_modff.c>
> >>> diff --git a/sysdeps/x86_64/fpu/multiarch/s_modff.c b/sysdeps/x86_64/fpu/multiarch/s_modff.c
> >>> index a4b5429037..f7351677a1 100644
> >>> --- a/sysdeps/x86_64/fpu/multiarch/s_modff.c
> >>> +++ b/sysdeps/x86_64/fpu/multiarch/s_modff.c
> >>> @@ -18,7 +18,6 @@
> >>>
> >>> #include <sysdeps/x86/isa-level.h>
> >>> #if MINIMUM_X86_ISA_LEVEL < AVX_X86_ISA_LEVEL
> >>> -# define NO_MATH_REDIRECT
> >>> # include <libm-alias-float.h>
> >>>
> >>> # define modff __redirect_modff
> >>> --
> >>> 2.43.0
> >>>
> >>
> >>
> >> --
> >> H.J.
> >
> >
> >
>
--
H.J.
More information about the Libc-alpha
mailing list