[SwitchLowering] Handle multiple destinations on condensed case stmts

Switch cases statements with sequential values that branch to the same
destination BB may often be handled together in a single new source BB.
In this scenario we need to remove remaining incoming values from PHI
instructions in the destination BB, as to match the number of source
branches.

Differential Revision: http://reviews.llvm.org/D6415

rdar://problem/19040894

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222926 91177308-0d34-0410-b5e6-96231b3b80d8
[LICM] Store sink and indirectbr instructions

Loop simplify skips exit-block insertion when exits contain indirectbr
instructions. This leads to an assertion in LICM when trying to sink
stores out of non-dedicated loop exits containing indirectbr
instructions. This patch fix this issue by re-checking for dedicated
exits in LICM prior to store sink attempts.

Differential Revision: http://reviews.llvm.org/D6414

rdar://problem/18943047

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222927 91177308-0d34-0410-b5e6-96231b3b80d8
InstCombine: FoldOrOfICmps harder

We may be in a situation where the icmps might not be near each other in
a tree of or instructions.  Try to dig out related compare instructions
and see if they combine.

N.B.  This won't fire on deep trees of compares because rewritting the
tree might end up creating a net increase of IR.  We may have to resort
to something more sophisticated if this is a real problem.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222928 91177308-0d34-0410-b5e6-96231b3b80d8