[llvm] [MachineCopyPropagation] Detect and fix suboptimal instruction order to enable optimizations (PR #98087)

[Quentin Colombet via llvm-commits]

qcolombet wrote:

I still think it should be part of a scheduling related implementation, because I don't want to recreate the dependency graph in MCP. My worry is that we don't track the right thing and we start breaking things or slowly but surely re-implement the whole DDG in MCP.

I'm surprised that the postRA scheduler doesn't try to get rid of the copies, but maybe this is what you should aim at fixing.

https://github.com/llvm/llvm-project/pull/98087