[llvm] [AMDGPU] Add flag to prevent reruns of LowerModuleLDS (PR #129520)

[Pierre van Houtryve via llvm-commits]

Pierre-vh wrote:

> Can you let us know when it runs multiple times, like when it runs the first time, and when it runs the second, etc.? I'm not sure this is an appropriate fix.

For the LTO pipeline it'd run once before splitting, and once after.

I don't know how else we can fix this, the pass apparently cannot detect nor handle re-runs, and the target machines/compiler instances are different between the two re-runs. The information has to be passed down somehow, and IR is the logical choice IMO.

https://github.com/llvm/llvm-project/pull/129520