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

[Quentin Colombet via llvm-commits]

qcolombet wrote:

> @qcolombet is your main concern the compile time impact or that there will be a lack of performance impact?

Compile time, or more precisely, it is okay to burn compile time if we get significant performance impact, otherwise the compile time impact needs to be kept at minimum.

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