Properly compose subregister indices when coalescing.
The comment about ordering of subreg indices is no longer true.
This exposed a bug in the new substVirtReg method that is also fixed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105294 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed