D'oh: duplicating the machine doesn't do you much good if you then
immediately discard the dupe and continue using the old one.
Merge commit '2aaa52a8de9206d613dc1aaedddf2a624448faf3'
More special cases for BDD quick simplify.
Fix up for compiler skew.
Add some missing cases to BDD quick simplify.
Add in a whole bunch of rules for simplifying multiplications.
Merge commit 'a1e920d'
Fix really stupid bug in aliasing analysis.
Unbreak the static alias stuff.
If we're doing static aliasing then we want to preserve the annotation
which says that a particular register definitely is or is not a valid
pointer even when we discard the rest of the data.  This marginally
reduces the number of summaries which we have to generate.