From aa0235dfdebffe9b338deba51f3ba563ee9b433d Mon Sep 17 00:00:00 2001 From: "Gabriel F. T. Gomes" Date: Mon, 2 Oct 2017 14:46:35 -0300 Subject: Add C++ versions of iscanonical for ldbl-96 and ldbl-128ibm (bug 22235) All representations of floating-point numbers in types with IEC 60559 binary exchange format are canonical. On the other hand, types with IEC 60559 extended formats, such as those implemented under ldbl-96 and ldbl-128ibm, contain representations that are not canonical. TS 18661-1 introduced the type-generic macro iscanonical, which returns whether a floating-point value is canonical or not. In Glibc, this type-generic macro is implemented using the macro __MATH_TG, which, when support for float128 is enabled, relies on __builtin_types_compatible_p to select between floating-point types. However, this use of iscanonical breaks C++ applications, because the builtin is only available in C mode. This patch provides a C++ implementation of iscanonical that relies on function overloading, rather than builtins, to select between floating-point types. Unlike the C++ implementations for iszero and issignaling, this implementation ignores __NO_LONG_DOUBLE_MATH. The double type always matches IEC 60559 double format, which is always canonical. Thus, when double and long double are the same (__NO_LONG_DOUBLE_MATH), iscanonical always returns 1 and is not implemented with __MATH_TG. Tested for powerpc64, powerpc64le and x86_64. [BZ #22235] * math/math.h: Trivial fix for unbalanced parentheses in comment. * math/Makefile [CXX] (tests): Add test-math-iscanonical.cc. (CFLAGS-test-math-iscanonical.cc): New variable. * math/test-math-iscanonical.cc: New file. * sysdeps/ieee754/ldbl-96/bits/iscanonical.h (iscanonical): Provide a C++ implementation based on function overloading, rather than using __MATH_TG, which uses C-only builtins. * sysdeps/ieee754/ldbl-128ibm/bits/iscanonical.h (iscanonical): Likewise. * sysdeps/powerpc/powerpc64le/Makefile (CFLAGS-test-math-iscanonical.cc): New variable. --- sysdeps/ieee754/ldbl-128ibm/bits/iscanonical.h | 21 +++++++++++++++++++-- sysdeps/ieee754/ldbl-96/bits/iscanonical.h | 19 ++++++++++++++++++- 2 files changed, 37 insertions(+), 3 deletions(-) (limited to 'sysdeps/ieee754') diff --git a/sysdeps/ieee754/ldbl-128ibm/bits/iscanonical.h b/sysdeps/ieee754/ldbl-128ibm/bits/iscanonical.h index 7ddb368d26..f756857c03 100644 --- a/sysdeps/ieee754/ldbl-128ibm/bits/iscanonical.h +++ b/sysdeps/ieee754/ldbl-128ibm/bits/iscanonical.h @@ -37,5 +37,22 @@ extern int __iscanonicall (long double __x) conversion, before being discarded; in IBM long double, there are encodings that are not consistently handled as corresponding to any particular value of the type, and we return 0 for those. */ -# define iscanonical(x) __MATH_TG ((x), __iscanonical, (x)) -#endif +# ifndef __cplusplus +# define iscanonical(x) __MATH_TG ((x), __iscanonical, (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 iscanonical (float __val) { return __iscanonicalf (__val); } +inline int iscanonical (double __val) { return __iscanonical (__val); } +inline int iscanonical (long double __val) { return __iscanonicall (__val); } +# if __HAVE_DISTINCT_FLOAT128 +inline int iscanonical (_Float128 __val) { return __iscanonicalf128 (__val); } +# endif +} +# endif /* __cplusplus */ +#endif /* __NO_LONG_DOUBLE_MATH */ diff --git a/sysdeps/ieee754/ldbl-96/bits/iscanonical.h b/sysdeps/ieee754/ldbl-96/bits/iscanonical.h index 4a4f4ad024..cfa36a0c2a 100644 --- a/sysdeps/ieee754/ldbl-96/bits/iscanonical.h +++ b/sysdeps/ieee754/ldbl-96/bits/iscanonical.h @@ -34,4 +34,21 @@ extern int __iscanonicall (long double __x) conversion, before being discarded; in extended precision, there are encodings that are not consistently handled as corresponding to any particular value of the type, and we return 0 for those. */ -#define iscanonical(x) __MATH_TG ((x), __iscanonical, (x)) +#ifndef __cplusplus +# define iscanonical(x) __MATH_TG ((x), __iscanonical, (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 iscanonical (float __val) { return __iscanonicalf (__val); } +inline int iscanonical (double __val) { return __iscanonical (__val); } +inline int iscanonical (long double __val) { return __iscanonicall (__val); } +# if __HAVE_DISTINCT_FLOAT128 +inline int iscanonical (_Float128 __val) { return __iscanonicalf128 (__val); } +# endif +} +#endif /* __cplusplus */ -- cgit 1.4.1