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[Bug tree-optimization/32390] tree-ssa-math-opts.c performs too many IL scans
- From: "paolo dot bonzini at lu dot unisi dot ch" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 19 Jun 2007 05:09:42 -0000
- Subject: [Bug tree-optimization/32390] tree-ssa-math-opts.c performs too many IL scans
- References: <bug-32390-91@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #4 from paolo dot bonzini at lu dot unisi dot ch 2007-06-19 05:09 -------
Subject: Re: tree-ssa-math-opts.c performs too
many IL scans
> We have reciprocal pass (in fact CSE recip pass) that CSEs 1.0/z from x/z, y/z,
> .../z. This is done by scanning function for RDIV_EXPR, where denominator (z)
> is the same. If 1.0/func() -> rfunc() conversion is done before recip pass, we
> loose the ability to scan for RDIV_EXPRs and the ability to CSE the division.
You could still use a pointer_set or pointer_map to save where the
RDIV_EXPRs are and avoid scanning the IL twice.
Paolo
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32390