[Bug tree-optimization/17863] [4.0/4.1/4.2/4.3 Regression] performance loss (not inlining as much??)

[amacleod at redhat dot com]

------- Comment #41 from amacleod at redhat dot com  2008-02-01 17:46 -------
TER will not replace any load into an expression if there is more than one use
of the load. Your sample shows multiple uses of each load. If it did this
substitution, it could be introducing worse code, it doesn't know.   (TER is
also strictly a single block replacement as well).

A stand alone register pressure analysis could determine that those loads
should all be substituted because pressure is too high on an 8 register
machine. If there were 128 register available however, then it may not want to
substitute the loads. TER just doesn't have that kind of information.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17863