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Provide a C++ version of iszero that does not use __MATH_TG (bug 21930)

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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.
This commit is contained in:
Gabriel F. T. Gomes
2017-08-22 16:34:42 -03:00
parent 56bc7f4360
commit 42496114ec
4 changed files with 127 additions and 5 deletions
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33
math/math.h
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@@ -513,15 +513,40 @@ inline int issignaling (_Float128 __val) { return __issignalingf128 (__val); }
# endif
# else /* __cplusplus */
extern "C++" {
# ifdef __SUPPORT_SNAN__
inline int
iszero (float __val)
{
return __fpclassifyf (__val) == FP_ZERO;
}
inline int
iszero (double __val)
{
return __fpclassify (__val) == FP_ZERO;
}
inline int
iszero (long double __val)
{
# ifdef __NO_LONG_DOUBLE_MATH
return __fpclassify (__val) == FP_ZERO;
# else
return __fpclassifyl (__val) == FP_ZERO;
# endif
}
# if __HAVE_DISTINCT_FLOAT128
inline int
iszero (_Float128 __val)
{
return __fpclassifyf128 (__val) == FP_ZERO;
}
# endif
# else
template <class __T> inline bool
iszero (__T __val)
{
# ifdef __SUPPORT_SNAN__
return fpclassify (__val) == FP_ZERO;
# else
return __val == 0;
# endif
}
# endif
} /* extern C++ */
# endif /* __cplusplus */
#endif /* Use IEC_60559_BFP_EXT. */