[lanai] Use peephole optimizer to generate more conditional ALU operations.

Summary:
* Similiar to the ARM backend yse the peephole optimizer to generate more conditional ALU operations;
* Add predicated type with default always true to RR instructions in LanaiInstrInfo.td;
* Move LanaiSetflagAluCombiner into optimizeCompare;
* The ASM parser can currently only handle explicitly specified CC, so specify ".t" (true) where needed in the ASM test;
* Remove unused MachineOperand flags;

Reviewers: eliben

Subscribers: aemerson

Differential Revision: http://reviews.llvm.org/D22072

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274807 91177308-0d34-0410-b5e6-96231b3b80d8
20 files changed