paves the way for future changes, increases coallescing opportunities (in
theory, not witnessed in practice), and eliminates the really expensive
LiveIntervals::overlapsAliases method.
llvm-svn: 29890
instructions which define each value#) to simplify and improve the coallescer.
In particular, this patch:
1. Implements iterative coallescing.
2. Reverts an unsafe hack from handlePhysRegDef, superceeding it with a
better solution.
3. Implements PR865, "coallescing" away the second copy in code like:
A = B
...
B = A
This also includes changes to symbolically print registers in intervals
when possible.
llvm-svn: 29862
