From 45970aa26d1af87b016ef95b4b35c566aeb6e841 Mon Sep 17 00:00:00 2001 From: "Gabriel F. T. Gomes" Date: Tue, 22 Aug 2017 16:34:42 -0300 Subject: [PATCH] Provide a C++ version of iszero that does not use __MATH_TG (bug 21930) 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. (cherry picked from commit 42496114ec0eb7d6d039d05d4262e109951c600c) [Romain rebase on glibc 2.26] Signed-off-by: Romain Naour --- math/math.h | 33 +++++++++++++-- math/test-math-iszero.cc | 79 ++++++++++++++++++++++++++++++++++++ sysdeps/powerpc/powerpc64le/Makefile | 3 +- 3 files changed, 110 insertions(+), 5 deletions(-) diff --git a/math/math.h b/math/math.h index 60dfa31..7c0fc6d 100644 --- a/math/math.h +++ b/math/math.h @@ -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 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. */ diff --git a/math/test-math-iszero.cc b/math/test-math-iszero.cc index 027e972..5c07261 100644 --- a/math/test-math-iszero.cc +++ b/math/test-math-iszero.cc @@ -22,6 +22,13 @@ #include +/* Support for _Float128 in std::numeric_limits is limited. + Include ieee754_float128.h and use the bitfields in the union + ieee854_float128.ieee_nan to build corner-case inputs. */ +#if __HAVE_DISTINCT_FLOAT128 +# include +#endif + static bool errors; static void @@ -72,12 +79,84 @@ check_type () std::numeric_limits::has_denorm == std::denorm_absent); } +#if __HAVE_DISTINCT_FLOAT128 +static void +check_float128 () +{ + ieee854_float128 q; + + q.d = 0.0Q; + CHECK (iszero (q.d), 1); + q.d = -0.0Q; + CHECK (iszero (q.d), 1); + q.d = 1.0Q; + CHECK (iszero (q.d), 0); + q.d = -1.0Q; + CHECK (iszero (q.d), 0); + + /* Normal min. */ + q.ieee.negative = 0; + q.ieee.exponent = 0x0001; + q.ieee.mantissa0 = 0x0000; + q.ieee.mantissa1 = 0x00000000; + q.ieee.mantissa2 = 0x00000000; + q.ieee.mantissa3 = 0x00000000; + CHECK (iszero (q.d), 0); + q.ieee.negative = 1; + CHECK (iszero (q.d), 0); + + /* Normal max. */ + q.ieee.negative = 0; + q.ieee.exponent = 0x7FFE; + q.ieee.mantissa0 = 0xFFFF; + q.ieee.mantissa1 = 0xFFFFFFFF; + q.ieee.mantissa2 = 0xFFFFFFFF; + q.ieee.mantissa3 = 0xFFFFFFFF; + CHECK (iszero (q.d), 0); + q.ieee.negative = 1; + CHECK (iszero (q.d), 0); + + /* Infinity. */ + q.ieee.negative = 0; + q.ieee.exponent = 0x7FFF; + q.ieee.mantissa0 = 0x0000; + q.ieee.mantissa1 = 0x00000000; + q.ieee.mantissa2 = 0x00000000; + q.ieee.mantissa3 = 0x00000000; + CHECK (iszero (q.d), 0); + + /* Quiet NaN. */ + q.ieee_nan.quiet_nan = 1; + q.ieee_nan.mantissa0 = 0x0000; + CHECK (iszero (q.d), 0); + + /* Signaling NaN. */ + q.ieee_nan.quiet_nan = 0; + q.ieee_nan.mantissa0 = 0x4000; + CHECK (iszero (q.d), 0); + + /* Denormal min. */ + q.ieee.negative = 0; + q.ieee.exponent = 0x0000; + q.ieee.mantissa0 = 0x0000; + q.ieee.mantissa1 = 0x00000000; + q.ieee.mantissa2 = 0x00000000; + q.ieee.mantissa3 = 0x00000001; + CHECK (iszero (q.d), 0); + q.ieee.negative = 1; + CHECK (iszero (q.d), 0); +} +#endif + static int do_test (void) { check_type (); check_type (); check_type (); +#if __HAVE_DISTINCT_FLOAT128 + check_float128 (); +#endif return errors; } diff --git a/sysdeps/powerpc/powerpc64le/Makefile b/sysdeps/powerpc/powerpc64le/Makefile index 19adbfa..dea2290 100644 --- a/sysdeps/powerpc/powerpc64le/Makefile +++ b/sysdeps/powerpc/powerpc64le/Makefile @@ -17,7 +17,8 @@ $(foreach suf,$(all-object-suffixes),$(objpfx)test-float128%$(suf)): CFLAGS += - $(foreach suf,$(all-object-suffixes),$(objpfx)test-ifloat128%$(suf)): CFLAGS += -mfloat128 CFLAGS-libm-test-support-float128.c += -mfloat128 CFLAGS-test-math-issignaling.cc += -mfloat128 -$(objpfx)test-float128% $(objpfx)test-ifloat128%: \ +CFLAGS-test-math-iszero.cc += -mfloat128 +$(objpfx)test-float128% $(objpfx)test-ifloat128% $(objpfx)test-math-iszero: \ gnulib-tests += $(f128-loader-link) endif -- 2.9.5