From c0b4353654e635e280ec0c1972f251bf696abb36 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 16 Dec 2016 18:03:25 +0000 Subject: Define FE_SNANS_ALWAYS_SIGNAL. TS 18661-1 defines a macro FE_SNANS_ALWAYS_SIGNAL in , to indicate that the recommended practice regarding sNaNs (that operations always produce a qNaN output with "invalid" exception, even in the fmax / fmin / hypot / pow cases where a qNaN input would not result in qNaN output) is followed. Now that those functions with C99 special cases for NaNs have been fixed not to apply those special cases to sNaN, only to qNaN, glibc follows that recommended practice. This patch makes it define the corresponding macro. Since compiler optimizations may affect whether sNaNs behave as expected and the macro relates to both language and library features, it is only defined if __SUPPORT_SNAN__ is defined (which GCC defines for -fsignaling-nans). It is also not defined if FE_INVALID is undefined, since the recommended practice specifically refers to raising the "invalid" exception, so it seems inappropriate to define the macro for soft-float cases without support for exceptions. (Further refinement would be possible in cases where bits/fenv.h is shared by configurations both with and without exceptions support.) Tested for x86_64 and x86, and also did compile-only testing for nios2 to cover the no-exceptions case. * math/fenv.h [__GLIBC_USE (IEC_60559_BFP_EXT) && FE_INVALID && __SUPPORT_SNAN__] (FE_SNANS_ALWAYS_SIGNAL): New macro. * math/test-fe-snans-always-signal.c: New file. * math/Makefile (tests): Add test-fe-snans-always-signal. (CFLAGS-test-fe-snans-always-signal.c): New variable. * manual/arith.texi (Infinity and NaN): Document FE_SNANS_ALWAYS_SIGNAL. --- math/Makefile | 5 ++++- math/fenv.h | 8 ++++++++ math/test-fe-snans-always-signal.c | 38 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 50 insertions(+), 1 deletion(-) create mode 100644 math/test-fe-snans-always-signal.c (limited to 'math') diff --git a/math/Makefile b/math/Makefile index 076fd34213..db6ea2932e 100644 --- a/math/Makefile +++ b/math/Makefile @@ -175,7 +175,8 @@ tests = test-matherr test-fenv atest-exp atest-sincos atest-exp2 basic-test \ test-fesetexcept-traps test-fetestexceptflag test-femode \ test-femode-traps test-iszero-excess-precision \ test-iseqsig-excess-precision test-flt-eval-method \ - test-fp-ilogb-constants test-fp-llogb-constants $(tests-static) + test-fp-ilogb-constants test-fp-llogb-constants \ + test-fe-snans-always-signal $(tests-static) tests-static = test-fpucw-static test-fpucw-ieee-static \ test-signgam-uchar-static test-signgam-uchar-init-static \ test-signgam-uint-static test-signgam-uint-init-static \ @@ -290,6 +291,8 @@ CFLAGS-test-iszero-excess-precision.c = -fexcess-precision=standard CFLAGS-test-iseqsig-excess-precision.c = -fexcess-precision=standard CFLAGS-test-flt-eval-method.c = -fexcess-precision=standard +CFLAGS-test-fe-snans-always-signal.c = -fsignaling-nans + # The -lieee module sets the _LIB_VERSION_ switch to IEEE mode # for error handling in the -lm functions. install-lib += libieee.a diff --git a/math/fenv.h b/math/fenv.h index 9006aa2fff..f7834472d8 100644 --- a/math/fenv.h +++ b/math/fenv.h @@ -145,6 +145,14 @@ extern int fesetmode (const femode_t *__modep) __THROW; # include #endif +/* NaN support. */ + +#if (__GLIBC_USE (IEC_60559_BFP_EXT) \ + && defined FE_INVALID \ + && defined __SUPPORT_SNAN__) +# define FE_SNANS_ALWAYS_SIGNAL 1 +#endif + #ifdef __USE_GNU /* Enable individual exceptions. Will not enable more exceptions than diff --git a/math/test-fe-snans-always-signal.c b/math/test-fe-snans-always-signal.c new file mode 100644 index 0000000000..2459febd08 --- /dev/null +++ b/math/test-fe-snans-always-signal.c @@ -0,0 +1,38 @@ +/* Test FE_SNANS_ALWAYS_SIGNAL definition. + Copyright (C) 2016 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include + +#ifdef FE_INVALID +# ifndef FE_SNANS_ALWAYS_SIGNAL +# error "FE_SNANS_ALWAYS_SIGNAL not defined" +# endif +#else +# ifdef FE_SNANS_ALWAYS_SIGNAL +# error "FE_SNANS_ALWAYS_SIGNAL defined, but no FE_INVALID support" +# endif +#endif + +int +do_test (void) +{ + /* This is a compilation test. */ + return 0; +} + +#include -- cgit v1.2.3