[llvm] [MachineSink] Some more preserving of debug location when rematerialising an instruction to replace a COPY (PR #73155)

[David Green via llvm-commits]

davemgreen wrote:

Can you add the sinkand-fold flag temporarily to DebugInfo/AArch64/constant-dbgloc.ll, to show it still working? It can be removed again later but helps show this is tested.

https://github.com/llvm/llvm-project/pull/73155