From 48b12ed54ceb605ec3566249c0387612fd9c0ced Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Tue, 12 Jun 2018 16:57:26 +0000 Subject: [PATCH] Do not use const attribute for nan functions (bug 23277). As in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86113 for __builtin_nan, bits/mathcalls.h wrongly declares the nan function with the __const__ attribute. Because the function reads memory pointed to by an argument, it's only pure, not const. This patch removes the incorrect attribute and adds a testcase for the bug. No __pure__ attribute is added to replace the incorrect __const__ one, since that would introduce problems when using GCC versions that have the incorrect built-in __const__ attribute and warn for the combination of those two attributes. Tested for x86_64. [BZ #23277] * math/bits/mathcalls.h [__USE_ISOC99] (nan): Do not use __const__ attribute. * math/test-nan-const.c: New file. * math/Makefile (tests): Add test-nan-const. (CFLAGS-test-nan-const.c): New variable. --- ChangeLog | 9 +++++++++ math/Makefile | 4 +++- math/bits/mathcalls.h | 2 +- math/test-nan-const.c | 32 ++++++++++++++++++++++++++++++++ 4 files changed, 45 insertions(+), 2 deletions(-) create mode 100644 math/test-nan-const.c diff --git a/ChangeLog b/ChangeLog index a0a4749b03..cb3edd3160 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,12 @@ +2018-06-12 Joseph Myers + + [BZ #23277] + * math/bits/mathcalls.h [__USE_ISOC99] (nan): Do not use __const__ + attribute. + * math/test-nan-const.c: New file. + * math/Makefile (tests): Add test-nan-const. + (CFLAGS-test-nan-const.c): New variable. + 2018-06-12 H.J. Lu * benchtests/scripts/compare_strings.py (process_results): Add diff --git a/math/Makefile b/math/Makefile index ea141cbf99..335b1fb197 100644 --- a/math/Makefile +++ b/math/Makefile @@ -235,7 +235,7 @@ tests = test-matherr-3 test-fenv basic-test \ test-iseqsig-excess-precision test-flt-eval-method \ test-fp-ilogb-constants test-fp-llogb-constants \ test-fe-snans-always-signal test-finite-macros test-narrow-macros \ - $(tests-static) + test-nan-const $(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 \ @@ -442,6 +442,8 @@ CFLAGS-test-fe-snans-always-signal.c += -fsignaling-nans CFLAGS-test-finite-macros.c += -ffinite-math-only +CFLAGS-test-nan-const.c += -fno-builtin + include ../Rules gen-all-calls = $(gen-libm-calls) $(gen-calls) diff --git a/math/bits/mathcalls.h b/math/bits/mathcalls.h index 92003639ab..cf87313e2f 100644 --- a/math/bits/mathcalls.h +++ b/math/bits/mathcalls.h @@ -198,7 +198,7 @@ __MATHCALLX (copysign,, (_Mdouble_ __x, _Mdouble_ __y), (__const__)); #ifdef __USE_ISOC99 /* Return representation of qNaN for double type. */ -__MATHCALLX (nan,, (const char *__tagb), (__const__)); +__MATHCALL (nan,, (const char *__tagb)); #endif diff --git a/math/test-nan-const.c b/math/test-nan-const.c new file mode 100644 index 0000000000..f7bba9eeb6 --- /dev/null +++ b/math/test-nan-const.c @@ -0,0 +1,32 @@ +/* Test nan functions do not have const attribute. Bug 23277. + Copyright (C) 2018 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 +#include + +static int +do_test (void) +{ + char buf[2] = { '2', 0 }; + float a = nanf (buf); + buf[0] = '3'; + float b = nanf (buf); + return memcmp (&a, &b, sizeof (float)) == 0; +} + +#include -- 2.43.5