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glibc/math/s_fmax_template.c
Adhemerval Zanella 13cfd77bf5 math: Don't redirect inlined builtin math functions
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>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
2025-11-17 11:17:07 -03:00

39 lines
1.2 KiB
C

/* Return maximum numeric value of X and Y.
Copyright (C) 1997-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <math.h>
FLOAT
M_DECL_FUNC (__fmax) (FLOAT x, FLOAT y)
{
#if M_USE_BUILTIN (FMAX)
return M_SUF (__builtin_fmax) (x, y);
#else
if (isgreaterequal (x, y))
return x;
else if (isless (x, y))
return y;
else if (issignaling (x) || issignaling (y))
return x + y;
else
return isnan (y) ? x : y;
#endif
}
declare_mgen_alias (__fmax, fmax);