[PATCH] math: Fix x86_64 build for -Os (BZ 33367)

[H.J. Lu]

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.

> +#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.