[Bug tree-optimization/32390] tree-ssa-math-opts.c performs too many IL scans

[paolo dot bonzini at lu dot unisi dot ch]

------- 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


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32390