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[Bug target/34702] [4.3 Regression] 1.0 is not the inverse of 1.0 with -mrecip on x86
- From: "ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 8 Jan 2008 08:42:14 -0000
- Subject: [Bug target/34702] [4.3 Regression] 1.0 is not the inverse of 1.0 with -mrecip on x86
- References: <bug-34702-12313@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #1 from ubizjak at gmail dot com 2008-01-08 08:42 -------
Hm, I don't see the reason, why this is a regression. What this PR shows is the
limitation of the precision of rcpss instruction.
Actually, this 2ulp precision is the reason, why -mrecip is not enabled by
default for -ffast-math.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34702