[llvm] [ARM] Create ConvertToComparesPass for ARM (PR #155530)

[Craig Topper via llvm-commits]

topperc wrote:

> > X86 does this for SUB at the start of `X86InstrInfo::optimizeCompareInstr` by marking SUB instructions with `isCompare` in tablegen.
> 
> That is going to be a bigger overhaul. This is something smaller first.

How so? Don't you just need to set isCompare and convert the opcode in ARMInstrInfo::optimizeCompareInstr?

https://github.com/llvm/llvm-project/pull/155530