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Provide a C++ version of issignaling that does not use __MATH_TG

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The macro __MATH_TG contains the logic to select between long double and
_Float128, when these types are ABI-distinct.  This logic relies on
__builtin_types_compatible_p, which is not available in C++ mode.

On the other hand, C++ function overloading provides the means to
distinguish between the floating-point types.  The overloading
resolution will match the correct parameter regardless of type
qualifiers, i.e.: const and volatile.

Tested for powerpc64le, s390x, and x86_64.

	* math/math.h [defined __cplusplus] (issignaling): Provide a C++
	definition for issignaling that does not rely on __MATH_TG,
	since __MATH_TG uses __builtin_types_compatible_p, which is only
	available in C mode.
	(CFLAGS-test-math-issignaling.cc): New variable.
	* math/Makefile [CXX] (tests): Add test-math-issignaling.
	* math/test-math-issignaling.cc: New test for C++ implementation
	of type-generic issignaling.
	* sysdeps/powerpc/powerpc64le/Makefile [subdir == math]
	(CXXFLAGS-test-math-issignaling.cc): Add -mfloat128 to the build
	options of test-math-issignaling on powerpc64le.
This commit is contained in:
Gabriel F. T. Gomes
2017-08-14 13:46:15 -03:00
parent 8d2ec55329
commit a16e8bc08e
5 changed files with 148 additions and 2 deletions
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19
math/math.h
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@ -474,7 +474,24 @@ enum
# include <bits/iscanonical.h>
/* Return nonzero value if X is a signaling NaN. */
# define issignaling(x) __MATH_TG ((x), __issignaling, (x))
# ifndef __cplusplus
# define issignaling(x) __MATH_TG ((x), __issignaling, (x))
# else
/* In C++ mode, __MATH_TG cannot be used, because it relies on
__builtin_types_compatible_p, which is a C-only builtin. On the
other hand, overloading provides the means to distinguish between
the floating-point types. The overloading resolution will match
the correct parameter (regardless of type qualifiers (i.e.: const
and volatile). */
extern "C++" {
inline int issignaling (float __val) { return __issignalingf (__val); }
inline int issignaling (double __val) { return __issignaling (__val); }
inline int issignaling (long double __val) { return __issignalingl (__val); }
# if __HAVE_DISTINCT_FLOAT128
inline int issignaling (_Float128 __val) { return __issignalingf128 (__val); }
# endif
} /* extern C++ */
# endif
/* Return nonzero value if X is subnormal. */
# define issubnormal(x) (fpclassify (x) == FP_SUBNORMAL)