[clang] [llvm] [Driver][AMDGPU][HIP][SPIRV] Disable optimizations for AMDGCN SPIR-V (PR #154765)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Not sure what loop(loop-idiom-vectorize) or globaldce are doing there at -O0, those seem like bugs

The loop-idiom-recognize [appears to be an aarch64 specific bug](https://github.com/llvm/llvm-project/issues/156787). I would also consider the globaldce to be a bug, but I assume it's just getting added as a set with the coroutine lowering 



https://github.com/llvm/llvm-project/pull/154765