Add fmaximum, fminimum functions

C2X adds new <math.h> functions for floating-point maximum and
minimum, corresponding to the new operations that were added in IEEE
754-2019 because of concerns about the old operations not being
associative in the presence of signaling NaNs.  fmaximum and fminimum
handle NaNs like most <math.h> functions (any NaN argument means the
result is a quiet NaN).  fmaximum_num and fminimum_num handle both
quiet and signaling NaNs the way fmax and fmin handle quiet NaNs (if
one argument is a number and the other is a NaN, return the number),
but still raise "invalid" for a signaling NaN argument, making them
exceptions to the normal rule that a function with a floating-point
result raising "invalid" also returns a quiet NaN.  fmaximum_mag,
fminimum_mag, fmaximum_mag_num and fminimum_mag_num are corresponding
functions returning the argument with greatest or least absolute
value.  All these functions also treat +0 as greater than -0.  There
are also corresponding <tgmath.h> type-generic macros.

Add these functions to glibc.  The implementations use type-generic
templates based on those for fmax, fmin, fmaxmag and fminmag, and test
inputs are based on those for those functions with appropriate
adjustments to the expected results.  The RISC-V maintainers might
wish to add optimized versions of fmaximum_num and fminimum_num (for
float and double), since RISC-V (F extension version 2.2 and later)
provides instructions corresponding to those functions - though it
might be at least as useful to add architecture-independent built-in
functions to GCC and teach the RISC-V back end to expand those
functions inline, which is what you generally want for functions that
can be implemented with a single instruction.

Tested for x86_64 and x86, and with build-many-glibcs.py.

1 files changed, 9 insertions, 0 deletions

diff --git a/math/gen-tgmath-tests.py b/math/gen-tgmath-tests.py
index 6d32a4b6e4..d433b484b8 100755
--- a/math/gen-tgmath-tests.py
+++ b/math/gen-tgmath-tests.py
@@ -707,6 +707,15 @@ class Tests(object):
                                 ('_Float32x', 'f32x'),
                                 ('_Float64x', 'f64x')):
                 self.add_tests(prefix + fn, ret, ['r'] * args)
+        # C2X functions.
+        self.add_tests('fmaximum', 'r', ['r', 'r'])
+        self.add_tests('fmaximum_mag', 'r', ['r', 'r'])
+        self.add_tests('fmaximum_num', 'r', ['r', 'r'])
+        self.add_tests('fmaximum_mag_num', 'r', ['r', 'r'])
+        self.add_tests('fminimum', 'r', ['r', 'r'])
+        self.add_tests('fminimum_mag', 'r', ['r', 'r'])
+        self.add_tests('fminimum_num', 'r', ['r', 'r'])
+        self.add_tests('fminimum_mag_num', 'r', ['r', 'r'])
         # Miscellaneous functions.
         self.add_tests('scalb', 's', ['s', 's'])