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authorJoseph Myers <joseph@codesourcery.com>2018-06-12 16:57:26 +0000
committerJoseph Myers <joseph@codesourcery.com>2018-06-12 16:57:26 +0000
commit48b12ed54ceb605ec3566249c0387612fd9c0ced (patch)
tree43a7f68212ad2c7597718969d1dd77e31188cee8 /math
parentcb8f6affed52d81819037b2f5d6f3a089abb8811 (diff)
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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.
Diffstat (limited to 'math')
-rw-r--r--math/Makefile4
-rw-r--r--math/bits/mathcalls.h2
-rw-r--r--math/test-nan-const.c32
3 files changed, 36 insertions, 2 deletions
diff --git a/math/Makefile b/math/Makefile
index ea141cb..335b1fb 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 9200363..cf87313 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 0000000..f7bba9e
--- /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
+ <http://www.gnu.org/licenses/>. */
+
+#include <math.h>
+#include <string.h>
+
+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 <support/test-driver.c>