Rewrite LiveVariable liveness computation. The new implementation is much simplified. It eliminated the nasty recursive routines and removed the partial def / use bookkeeping. There is also potential for performance improvement by replacing the conservative handling of partial physical register definitions. The code is currently disabled until live interval analysis is taught of the name scheme.
This patch also fixed a couple of nasty corner cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@49784
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