[llvm] [RISCV] Don't run loop-idiom-vectorize pass in the O0 pipeline. (PR #156798)

[Min-Yih Hsu via llvm-commits]

mshockwave wrote:

> I kind of would expect "LateLoopOptimizations" to not be called in the -O0 pipeline setup, rather than every target needing to make all of these optional points no-ops

What I understand is that not just late loop optimization, but these extension point / callbacks in general will always be invoked even in O0 pipelines which barely have any meaningful optimizations. I guess it was for maintaining a consistency in behavior

https://github.com/llvm/llvm-project/pull/156798