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[Bug other/23469] Behaviour of built-in __signbitf(x) differs with optimization
- From: "ddneilson at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 21 Aug 2005 20:28:52 -0000
- Subject: [Bug other/23469] Behaviour of built-in __signbitf(x) differs with optimization
- References: <20050818204303.23469.ddneilson@gmail.com>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From ddneilson at gmail dot com 2005-08-21 20:28 -------
One of the really odd things, that makes me still think this is a bug in some
way is that the definition of "mysignbit()" that I gave in signbit.cpp is
identical to the definition of __signbitf(x) as given in bits/mathinline.h. But,
yet, when optimizations aren't turned on the two functions have differing return
values; mysignbit() will return 1 iff the signbit is set, whereas __signbitf()
will return 0x80000000 iff the signbit is set.
Furthermore, when all documented -O1 flags are turned on manually (without
actually using -O1) the output of __signbitf(x) is the same as the unoptimized
version; it only differs when one of the -On flags are used.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |UNCONFIRMED
Resolution|INVALID |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23469