[Bug tree-optimization/62217] [4.9/5 Regression] DOM confuses complete unrolling which in turn causes VRP to warn

law at redhat dot com gcc-bugzilla@gcc.gnu.org
Fri Feb 13 23:29:00 GMT 2015


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62217

--- Comment #7 from Jeffrey A. Law <law at redhat dot com> ---
But replacement with the most dominating name (presumably a default def
dominates everything) isn't going to help here.

In many ways we'd be better off if we didn't propagate from those equality
comparisons -- unless they allowed some other later simplification.  But we
don't have a good way to make that determination.  Which ultimately let to the
uncprop pass which we run very late to try and put things back the way they
were.

I wonder if running uncprop between DOM1 & the late unroller would be worth the
extra pass.  And if so, where does it make the most sense.



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