glibc/sysdeps/i386/i686/fpu/s_fmax.S

/* Compute maximum of two numbers, regarding NaN as missing argument.
   Copyright (C) 1997-2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.

   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 <sysdep.h>
#include <libm-alias-double.h>

	.text
ENTRY(__fmax)
	fldl	4(%esp)		// x
	fldl	12(%esp)	// x : y

	fucomi	%st(0), %st
	fcmovu	%st(1), %st	// now %st contains y if not NaN, x otherwise

	fxch

	fucomi	%st(1), %st
	fcmovb	%st(1), %st

	fstp	%st(1)

	ret
END(__fmax)
libm_alias_double (__fmax, fmax)