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[Bug tree-optimization/15256] [tree-ssa] Optimize manual bitfield manipilation.
- From: "segher at kernel dot crashing dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 18 May 2004 11:45:32 -0000
- Subject: [Bug tree-optimization/15256] [tree-ssa] Optimize manual bitfield manipilation.
- References: <20040503080351.15256.kazu@cs.umass.edu>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From segher at kernel dot crashing dot org 2004-05-18 11:45 -------
Subject: Re: New: [tree-ssa] Optimize manual bitfield manipilation.
The generic rule is
X | (Y ^ Z) == (X | Y) ^ Z if X & (Y ^ Z) == 0
(because then it is just X ^ Y ^ Z -- dunno if you want to go
that far -- but that sure would be nice).
Segher
(everything should be canonicalized to (n)ands (and maybe xors)...
or == doubt == wrong).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15256