aboutsummaryrefslogtreecommitdiff
path: root/math/math.h
diff options
context:
space:
mode:
authorJoseph Myers <joseph@codesourcery.com>2016-09-28 21:11:58 +0000
committerJoseph Myers <joseph@codesourcery.com>2016-09-28 21:11:58 +0000
commitb59ad2db99df74326ae28926299469eecce6f468 (patch)
treec18cd839284e4ce4ca1b9edc06a4f61032c077f4 /math/math.h
parente83be730910c341f2f02ccc207b0586bb04fc21a (diff)
downloadglibc-b59ad2db99df74326ae28926299469eecce6f468.tar
glibc-b59ad2db99df74326ae28926299469eecce6f468.tar.gz
glibc-b59ad2db99df74326ae28926299469eecce6f468.tar.bz2
glibc-b59ad2db99df74326ae28926299469eecce6f468.zip
Fix iszero for excess precision.
Floating-point classification macros are supposed to remove any excess range or precision from their arguments. This patch fixes the non-sNaN version of iszero to do so, by casting the argument to its own type. (This will of course work only for standard-conforming excess precision, not for what GCC does on 32-bit x86 by default where the back end hides excess precision from the front end; the same applies to most of the classification macros in that case, as showed up when we made them use GCC built-in functions.) (iseqsig will have the reverse issue, needing to ensure that when an underlying function is used it's for a type wide enough not to remove any excess precision, since comparison macros must not remove excess precision.) Tested for x86_64 and x86. * math/math.h [__GLIBC_USE (IEC_60559_BFP_EXT) && !__SUPPORT_SNAN__] (iszero): Cast argument to its own type. * math/test-iszero-excess-precision.c: New file. * math/Makefile (tests): Add test-iszero-excess-precision. (CFLAGS-test-iszero-excess-precision.c): New variable.
Diffstat (limited to 'math/math.h')
-rw-r--r--math/math.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/math/math.h b/math/math.h
index 0a099596f1..1382baa75a 100644
--- a/math/math.h
+++ b/math/math.h
@@ -336,7 +336,7 @@ enum
# ifdef __SUPPORT_SNAN__
# define iszero(x) (fpclassify (x) == FP_ZERO)
# else
-# define iszero(x) ((x) == 0)
+# define iszero(x) (((__typeof (x)) (x)) == 0)
# endif
#endif /* Use IEC_60559_BFP_EXT. */