[RegisterCoalescer] Add wrapper for Erasing Instructions
Summary:
To delete an instruction the coalescer needs to call eraseFromParent()
on the MachineInstr, insert it in the ErasedInstrs list and update the
Live Ranges structure. This patch re-factors the code to do all that in
one function. This will also fix cases where previous code wasn't
inserting deleted instructions in the ErasedList.
Reviewers: qcolombet, kparzysz
Reviewed By: qcolombet
Subscribers: MatzeB, llvm-commits, qcolombet
Differential Revision: https://reviews.llvm.org/D36204
llvm-svn: 309915