[RegisterCoalescer] Add a rule to consider more profitable copies first when
those are in the same basic block.
The previous approach was the topological order of the basic block.

By default this rule is disabled.

Related to PR22768.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233241 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed