[clang] [llvm] [RegisterCoalescer] Improve register allocation for return values by limiting rematerialization (PR #163047)

[Antonio Frighetto via llvm-commits]

antoniofrighetto wrote:

> I don't feel this is the right way to fix this problem. This looks like too specific and not really a coalescing problem.

Could you please provide an alternative direction for this? I second this is not a coalescing problem, though couldn't we let RegisterCoalescer avoid suboptimally recomputing the constant value when unneeded, as in cases above?

https://github.com/llvm/llvm-project/pull/163047