[PATCH v2 09/28] math: Don't redirect inlined builtin math functions
H.J. Lu
hjl.tools@gmail.com
Tue Oct 28 19:05:28 GMT 2025
On Wed, Oct 29, 2025 at 1:12 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
> When we want to inline builtin math functions, like truncf, for
>
> extern float truncf (float __x) __attribute__ ((__nothrow__ )) __attribute__ ((__const__));
> extern float __truncf (float __x) __attribute__ ((__nothrow__ )) __attribute__ ((__const__));
>
> float (truncf) (float) asm ("__truncf");
>
> compiler may redirect truncf calls to __truncf, instead of inlining it
> (for instance, clang). The USE_TRUNCF_BUILTIN is 1 to indicate that
> truncf should be inlined. In this case, we don't want the truncf
> redirection:
>
> 1. For each math function which may be inlined, we define
>
> #if USE_TRUNCF_BUILTIN
> # define NO_truncf_BUILTIN inline_truncf
> #else
> # define NO_truncf_BUILTIN truncf
> #endif
>
> in <math-use-builtins.h>.
>
> 2. Include <math-use-builtins.h> in include/math.h.
>
> 3. Change MATH_REDIRECT to
>
> #define MATH_REDIRECT(FUNC, PREFIX, ARGS) \
> float (NO_ ## FUNC ## f ## _BUILTIN) (ARGS (float)) \
> asm (PREFIX #FUNC "f");
>
> With this change If USE_TRUNCF_BUILTIN is 0, we get
>
> float (truncf) (float) asm ("__truncf");
> truncf will be redirected to __truncf.
>
> And for USE_TRUNCF_BUILTIN 1, we get:
>
> float (inline_truncf) (float) asm ("__truncf");
>
> In both cases either truncf will be inlined or the internal alias
> (__truncf) will be called.
>
> It is not required for all math-use-builtin symbol, only the one
> defined in math.h. It also allows to remove all the math-use-builtin
> inclusion, since it is now implicitly included by math.h.
>
> For MIPS, some math-use-builtin headers include sysdep.h and this
> in turn includes a lot of extra headers that do not allow ldbl-128
> code to override alias definition (math.h will include
> some stdlib.h definition). The math-use-builtin only requires
> the __mips_isa_rev, so move the defintion to sgidefs.h.
>
> Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
> Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> include/math.h | 19 +-
> math/s_fmax_template.c | 1 -
> math/s_fmin_template.c | 2 -
> sysdeps/generic/math-use-builtins-copysign.h | 2 +
> sysdeps/generic/math-use-builtins.h | 196 ++++++++++++++++++
> sysdeps/ieee754/dbl-64/e_hypot.c | 1 -
> sysdeps/ieee754/dbl-64/e_sqrt.c | 1 -
> sysdeps/ieee754/dbl-64/s_ceil.c | 1 -
> sysdeps/ieee754/dbl-64/s_floor.c | 1 -
> sysdeps/ieee754/dbl-64/s_fma.c | 1 -
> sysdeps/ieee754/dbl-64/s_fmaf.c | 1 -
> sysdeps/ieee754/dbl-64/s_llrint.c | 1 -
> sysdeps/ieee754/dbl-64/s_llround.c | 1 -
> sysdeps/ieee754/dbl-64/s_logb.c | 2 -
> sysdeps/ieee754/dbl-64/s_lrint.c | 1 -
> sysdeps/ieee754/dbl-64/s_lround.c | 1 -
> sysdeps/ieee754/dbl-64/s_modf.c | 1 -
> sysdeps/ieee754/dbl-64/s_nearbyint.c | 1 -
> sysdeps/ieee754/dbl-64/s_rint.c | 1 -
> sysdeps/ieee754/dbl-64/s_round.c | 2 -
> sysdeps/ieee754/dbl-64/s_roundeven.c | 1 -
> sysdeps/ieee754/dbl-64/s_trunc.c | 2 -
> sysdeps/ieee754/float128/float128_private.h | 1 -
> sysdeps/ieee754/flt-32/e_sqrtf.c | 1 -
> sysdeps/ieee754/flt-32/s_ceilf.c | 1 -
> sysdeps/ieee754/flt-32/s_floorf.c | 1 -
> sysdeps/ieee754/flt-32/s_llrintf.c | 1 -
> sysdeps/ieee754/flt-32/s_llroundf.c | 1 -
> sysdeps/ieee754/flt-32/s_logbf.c | 1 -
> sysdeps/ieee754/flt-32/s_lrintf.c | 1 -
> sysdeps/ieee754/flt-32/s_lroundf.c | 1 -
> sysdeps/ieee754/flt-32/s_modff.c | 1 -
> sysdeps/ieee754/flt-32/s_nearbyintf.c | 1 -
> sysdeps/ieee754/flt-32/s_rintf.c | 1 -
> sysdeps/ieee754/flt-32/s_roundevenf.c | 1 -
> sysdeps/ieee754/flt-32/s_roundf.c | 1 -
> sysdeps/ieee754/flt-32/s_truncf.c | 1 -
> sysdeps/ieee754/ldbl-128/s_ceill.c | 1 -
> sysdeps/ieee754/ldbl-128/s_copysignl.c | 1 -
> sysdeps/ieee754/ldbl-128/s_floorl.c | 1 -
> sysdeps/ieee754/ldbl-128/s_fma.c | 1 -
> sysdeps/ieee754/ldbl-128/s_fmal.c | 1 -
> sysdeps/ieee754/ldbl-128/s_llrintl.c | 1 -
> sysdeps/ieee754/ldbl-128/s_logbl.c | 1 -
> sysdeps/ieee754/ldbl-128/s_lrintl.c | 1 -
> sysdeps/ieee754/ldbl-128/s_nearbyintl.c | 1 -
> sysdeps/ieee754/ldbl-128/s_rintl.c | 1 -
> sysdeps/ieee754/ldbl-128/s_roundevenl.c | 1 -
> sysdeps/ieee754/ldbl-128/s_roundl.c | 1 -
> sysdeps/ieee754/ldbl-128/s_truncl.c | 1 -
> sysdeps/ieee754/ldbl-128ibm/s_fabsl.c | 1 -
> sysdeps/ieee754/ldbl-96/s_fabsl.c | 1 -
> sysdeps/mips/fpu/math-use-builtins-fma.h | 2 +-
> sysdeps/mips/math-use-builtins-ffs.h | 2 +-
> sysdeps/mips/sgidefs.h | 3 +
> sysdeps/powerpc/fpu/e_sqrt.c | 1 -
> sysdeps/powerpc/fpu/e_sqrtf.c | 1 -
> sysdeps/unix/mips/sysdep.h | 3 -
> sysdeps/x86_64/fpu/multiarch/s_modf-avx.c | 4 -
> sysdeps/x86_64/fpu/multiarch/s_modf-sse4_1.c | 4 -
> sysdeps/x86_64/fpu/multiarch/s_modff-avx.c | 4 -
> sysdeps/x86_64/fpu/multiarch/s_modff-sse4_1.c | 4 -
> 62 files changed, 216 insertions(+), 82 deletions(-)
>
> diff --git a/include/math.h b/include/math.h
> index 9ba4708801..0fac2fda84 100644
> --- a/include/math.h
> +++ b/include/math.h
> @@ -139,25 +139,32 @@ fabsf128 (_Float128 x)
> /* NB: Internal tests don't have access to internal symbols. */
> # if !IS_IN (testsuite_internal) \
> && !(defined __FINITE_MATH_ONLY__ && __FINITE_MATH_ONLY__ > 0)
> +/* NB: Do not redirect math builtin functions when they are inlined. */
> +# include <math-use-builtins.h>
> # ifndef NO_MATH_REDIRECT
Is it possible to remove NO_MATH_REDIRECT?
> /* Declare some functions for use within GLIBC. Compilers typically
> inline those functions as a single instruction. Use an asm to
> avoid use of PLTs if it doesn't. */
> # define MATH_REDIRECT(FUNC, PREFIX, ARGS) \
> - float (FUNC ## f) (ARGS (float)) asm (PREFIX #FUNC "f"); \
> - double (FUNC) (ARGS (double)) asm (PREFIX #FUNC ); \
> + float (NO_ ## FUNC ## f ## _BUILTIN) (ARGS (float)) \
> + asm (PREFIX #FUNC "f"); \
> + double (NO_ ## FUNC ## _BUILTIN) (ARGS (double)) \
> + asm (PREFIX #FUNC ); \
> MATH_REDIRECT_LDBL (FUNC, PREFIX, ARGS) \
> MATH_REDIRECT_F128 (FUNC, PREFIX, ARGS)
> +
> # if defined __NO_LONG_DOUBLE_MATH \
> || __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
> # define MATH_REDIRECT_LDBL(FUNC, PREFIX, ARGS)
> # else
> -# define MATH_REDIRECT_LDBL(FUNC, PREFIX, ARGS) \
> - long double (FUNC ## l) (ARGS (long double)) asm (PREFIX #FUNC "l");
> +# define MATH_REDIRECT_LDBL(FUNC, PREFIX, ARGS) \
> + long double (NO_ ## FUNC ## l ## _BUILTIN) (ARGS (long double)) \
> + asm (PREFIX #FUNC "l");
> # endif
> # if __HAVE_DISTINCT_FLOAT128
> -# define MATH_REDIRECT_F128(FUNC, PREFIX, ARGS) \
> - _Float128 (FUNC ## f128) (ARGS (_Float128)) asm (PREFIX #FUNC "f128");
> +# define MATH_REDIRECT_F128(FUNC, PREFIX, ARGS) \
> + _Float128 (NO_ ## FUNC ## f128 ## _BUILTIN) (ARGS (_Float128)) \
> + asm (PREFIX #FUNC "f128");
> # else
> # define MATH_REDIRECT_F128(FUNC, PREFIX, ARGS)
> # endif
--
H.J.
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