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

Mon Sep 8 15:27:22 GMT 2025

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?

> 
>>> +#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.
> 
> 
> 