Fix ScalarEvolutionExpander when creating a PHI in a block with duplicate predecessors

It seems that when I fixed this, almost exactly a year ago, I did not quite do
it correctly. When we have duplicate block predecessors, we can indeed not have
different incoming values for the same block, but we *must* have duplicate
entries. So, instead of skipping the duplicates, we explicitly add the
duplicate incoming values.

Fixes PR20442.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214423 91177308-0d34-0410-b5e6-96231b3b80d8
Move MCObjectSymbolizer.h to MC/MCAnalysis.

The cpp file is already in lib/MC/MCAnalysis.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214424 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unused argument.

Thanks to Justin Bogner for noticing it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214426 91177308-0d34-0410-b5e6-96231b3b80d8
Disable IsSub subregister assert.  pr18663.

This is a follow-up to the activity in the bug at
http://llvm.org/bugs/show_bug.cgi?id=18663 .  The underlying issue has
to do with how the KILL pseudo-instruction is handled.  I defer to
Hal/Jakob/Uli for additional details and background.

This will disable the (bad?) assert, add an associated fixme comment,
and add a pair of tests.

The code change and the pr18663-2.ll test are copied from the referenced
bug.  That test does not immediately fail in my environment, but I have
added the pr18663.ll test which does.

(Comment from Hal)
to provide everyone else with some context, this assert was not bad when
it was written. At that time, we only generated KILL pseudo instructions
around subregister copies. This logic, unfortunately, had its own problems.
In r199797, the relevant logic in MachineCopyPropagation was replaced to
generate KILLs for other kinds of copies too. This change in semantics broke
this now-problematic assumption in AggressiveAntiDepBreaker. The
AggressiveAntiDepBreaker really needs a proper cleanup to deal with the
change, but removing the assert (which just allows the function to return
false) is a safe conservative behavior, and should do for the time being.






git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214429 91177308-0d34-0410-b5e6-96231b3b80d8