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[Bug target/52593] Builtin sqrt on x86 is not correctly rounded
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 16 Mar 2012 10:53:12 +0000
- Subject: [Bug target/52593] Builtin sqrt on x86 is not correctly rounded
- Auto-submitted: auto-generated
- References: <bug-52593-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52593
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |wrong-code
Target| |i?86-*-*
Status|WAITING |NEW
Version|unknown |4.6.4
--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-03-16 10:53:12 UTC ---
Confirmed. I think sqrt is special (compared to sin, cos, etc.) because it's
one of the core IEEE arithmetic functions. I suppose correct rounding
is only ensured for 80bit long double.
It will of course be an unexpected performance drop for most people with
no additional benefit as the libm implementation is wrong as well :/