[tcb] Fix PR 18178
Diego Novillo
dnovillo@redhat.com
Sat Feb 19 02:28:00 GMT 2005
This patch addresses some of the FIXME notes in the VRP pass. The main
change is the inclusion of scalar evolution information in range
propagation to derive narrower ranges. This allows us to remove the
bound checking code in PR 18178.
I needed to jump through a few hoops to get scalar evolution
information. It is currently a bit too intertwined with loop
optimization passes, which is understandable. But I would like to have
a point of entry to the analyzer that didn't force us to do all the
initialization in each pass (see the code that was added to
execute_vrp). Sebastian, is that feasible?
The patch also teaches VRP to do some limited symbolic comparisons to
take advantage of the loop information given by scev. More testing is
still needed to see the effects on mudflap and other Java code. But I
am avoiding doing too many changes at once.
Bootstrapped and tested x86, x86-64, ia64 and ppc.
Diego.
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