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glibc/math/libm-test-fmax.inc
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Adhemerval ZanellaandJames Y Knight bdb07a03fb math: Order signed zeros in f{max,min}{f,l,f128} 
The C standard (at least from C99 until C23) does not require
fmin/fmax to order zeros by their sign, so glibc's previous behavior
was entirely standards-conforming.  However, the standard does
recommend that zeros be ordered in a footnote, saying:

"If possible, fmax is sensitive to the sign of zero, for example
fmax(−0.0, +0.0) ideally returns +0."

As this is indeed possible (and not too complicated), implement it as
a quality-of-implementation improvement.  It also remove possible
deviations between architectures, where for some architectures that
has direct mapping instruction (USE_FMA*_BUILTIN) they already do
the ordering.

Checked on x86_64-linux-gnu, aarch64-linux-gnu, i686-linux-gnu,
arm-linux-gnueabihf, powerpc64le-linux-gnu,
riscv64-linux-gnu-rv64imafdc-lp64d, and loongarch64-linux-gnuf64.

Co-authored-by: James Y Knight <jyknight@google.com>
Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>
2026-02-02 14:35:19 -03:00

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/* Test fmax.
Copyright (C) 1997-2026 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 "libm-test-driver.c"
static const struct test_ff_f_data fmax_test_data[] =
{
TEST_ff_f (fmax, 0, 0, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, minus_zero, minus_zero, minus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
/* The order signed zeros are implemented as a QoI in the generic implementation
and expected for USE_F{MIN,MAX}{F,L,F128}_BUILTIN. */
TEST_ff_f (fmax, 0, minus_zero, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, minus_zero, 0, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, min_subnorm_value, -min_subnorm_value, min_subnorm_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -min_subnorm_value, min_subnorm_value, min_subnorm_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, min_value, -min_value, min_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -min_value, min_value, min_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, max_value, -max_value, max_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -max_value, max_value, max_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, 9, 0, 9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, 0, 9, 9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -9, 0, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, 0, -9, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, plus_infty, 9, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, 0, plus_infty, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -9, plus_infty, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, plus_infty, -9, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, minus_infty, 9, 9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, minus_infty, -9, -9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, 9, minus_infty, 9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -9, minus_infty, -9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, 0, qnan_value, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, 0, -qnan_value, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, minus_zero, qnan_value, minus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, minus_zero, -qnan_value, minus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, 9, qnan_value, 9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, 9, -qnan_value, 9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -9, qnan_value, -9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -9, -qnan_value, -9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, 0, snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, 0, -snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, minus_zero, snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, minus_zero, -snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, 9, snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, 9, -snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -9, snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -9, -snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, qnan_value, 0, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -qnan_value, 0, 0, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, qnan_value, minus_zero, minus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -qnan_value, minus_zero, minus_zero, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, qnan_value, 9, 9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -qnan_value, 9, 9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, qnan_value, -9, -9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -qnan_value, -9, -9, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, snan_value, 0, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -snan_value, 0, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, snan_value, minus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -snan_value, minus_zero, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, snan_value, 9, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -snan_value, 9, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, snan_value, -9, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -snan_value, -9, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, plus_infty, qnan_value, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, plus_infty, -qnan_value, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, minus_infty, qnan_value, minus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, minus_infty, -qnan_value, minus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, plus_infty, snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, plus_infty, -snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, minus_infty, snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, minus_infty, -snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, qnan_value, plus_infty, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -qnan_value, plus_infty, plus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, qnan_value, minus_infty, minus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -qnan_value, minus_infty, minus_infty, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, snan_value, plus_infty, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -snan_value, plus_infty, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, snan_value, minus_infty, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -snan_value, minus_infty, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, qnan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, qnan_value, -qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -qnan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, -qnan_value, -qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
TEST_ff_f (fmax, qnan_value, snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, qnan_value, -snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -qnan_value, snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -qnan_value, -snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, snan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, snan_value, -qnan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -snan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -snan_value, -qnan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, snan_value, snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, snan_value, -snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -snan_value, snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
TEST_ff_f (fmax, -snan_value, -snan_value, qnan_value, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION),
};
static void
fmax_test (void)
{
ALL_RM_TEST (fmax, 1, fmax_test_data, RUN_TEST_LOOP_ff_f, END);
}
static void
do_test (void)
{
fmax_test ();
}
/*
* Local Variables:
* mode:c
* End:
*/
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