[llvm] [AMDGPU][VOPD] Limit VOPDPairing from reaching over load dependencies (PR #201930)

[Zach Goldthorpe via llvm-commits]

zGoldthorpe wrote:

The current version is still a work in progress, but implements a pairing check that tries to look at transitively-dependent loads. The implementation could use optimisation, and has caused some scheduling churn (some of which I presume is from calling `DAG->IsReachable`) that I need to look into, but I want to see how people find this approach at least in theory.

Feedback is much appreciated!

https://github.com/llvm/llvm-project/pull/201930