[llvm] [AMDGPU] Constrain AV->VReg if we do not exceed RP thresholds (PR #150086)

[Shilei Tian via llvm-commits]

================
@@ -1130,6 +1130,15 @@ bool PreRARematStage::initGCNSchedStage() {
 }
 
 void GCNSchedStage::finalizeGCNSchedStage() {
+  unsigned MaxArchVGPR = 0;
+  for (auto P : DAG.Pressure) {
+    if (P.getArchVGPRNum() > MaxArchVGPR)
+      MaxArchVGPR = P.getArchVGPRNum();
----------------
shiltian wrote:

```suggestion
    MaxArchVGPR = std::max(MaxArchVGPR, P.getArchVGPRNum());
```

https://github.com/llvm/llvm-project/pull/150086