When signaling nans are enabled (with -fsignaling-nans), the C++ version
of iszero uses the fpclassify macro, which is defined with __MATH_TG.
However, when support for float128 is available, __MATH_TG uses the
builtin __builtin_types_compatible_p, which is only available in C mode.
This patch refactors the C++ version of iszero so that it uses function
overloading to select between the floating-point types, instead of
relying on fpclassify and __MATH_TG.
Tested for powerpc64le, s390x, x86_64, and with build-many-glibcs.py.
[BZ #21930]
* math/math.h [defined __cplusplus && defined __SUPPORT_SNAN__]
(iszero): New C++ implementation that does not use
fpclassify/__MATH_TG/__builtin_types_compatible_p, when
signaling nans are enabled, since __builtin_types_compatible_p
is a C-only feature.
* math/test-math-iszero.cc: When __HAVE_DISTINCT_FLOAT128 is
defined, include ieee754_float128.h for access to the union and
member ieee854_float128.ieee.
[__HAVE_DISTINCT_FLOAT128] (do_test): Call check_float128.
[__HAVE_DISTINCT_FLOAT128] (check_float128): New function.
* sysdeps/powerpc/powerpc64le/Makefile [subdir == math]
(CXXFLAGS-test-math-iszero.cc): Add -mfloat128 to the build
options of test-math-zero on powerpc64le.
As noted in bug 21607, NO_LONG_DOUBLE conditionals in libm tests are
no longer effective. For most this is harmless - they were only
present because of long double functions not being declared with _LIBC
defined, and _LIBC is no longer defined for building most tests. For
the few where this is actually relevant to the test, testing
LDBL_MANT_DIG > DBL_MANT_DIG is more appropriate as that limits the
test to public APIs. This patch fixes the tests accordingly.
Tested for x86_64 and arm.
[BZ #21607]
* math/basic-test.c [!NO_LONG_DOUBLE]: Change conditionals to
[LDBL_MANT_DIG > DBL_MANT_DIG].
* math/bug-nextafter.c [!NO_LONG_DOUBLE]: Remove conditionals.
* math/bug-nexttoward.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-math-isinff.cc [!NO_LONG_DOUBLE]: Likewise.
* math/test-math-iszero.cc [!NO_LONG_DOUBLE]: Likewise.
* math/test-nan-overflow.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-nan-payload.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-nearbyint-except-2.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-nearbyint-except.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-powl.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-signgam-finite-c99.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-signgam-finite.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-signgam-main.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-snan.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-tgmath-ret.c [!NO_LONG_DOUBLE]: Likewise.
* math/test-tgmath.c: Include <float.h>.
[!NO_LONG_DOUBLE]: Change conditionals to [LDBL_MANT_DIG >
DBL_MANT_DIG].
* math/test-tgmath2.c: Include <float.h>.
[!NO_LONG_DOUBLE]: Change conditionals to [LDBL_MANT_DIG >
DBL_MANT_DIG].
