Improve scheduling with branch coalescing

This patch adds a MachineSSA pass that coalesces blocks that branch
on the same condition.

Committing on behalf of Lei Huang.

Differential Revision: https://reviews.llvm.org/D28249


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296670 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed