[llvm] [AMDGPU][MachineScheduler] Alternative way to control excess RP. (PR #68004)

[Matt Arsenault via llvm-commits]

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@@ -1127,16 +1128,23 @@ bool OccInitialScheduleStage::shouldRevertScheduling(unsigned WavesAfter) {
 bool UnclusteredHighRPStage::shouldRevertScheduling(unsigned WavesAfter) {
   // If RP is not reduced in the unclustered reschedule stage, revert to the
   // old schedule.
-  if ((WavesAfter <= PressureBefore.getOccupancy(ST) &&
-       mayCauseSpilling(WavesAfter)) ||
-      GCNSchedStage::shouldRevertScheduling(WavesAfter)) {
-    LLVM_DEBUG(dbgs() << "Unclustered reschedule did not help.\n");
-    return true;
-  }
+  if (DAG.RegionsWithExcessRP[RegionIdx]) {
+    unsigned NewVGPRRP = PressureAfter.getVGPRNum(false);
+    unsigned NewAGPRRP = PressureAfter.getAGPRNum();
+    unsigned NewSGPRRP = PressureAfter.getSGPRNum();
 
-  // Do not attempt to relax schedule even more if we are already spilling.
-  if (isRegionWithExcessRP())
+    unsigned OldVGPRRP = PressureBefore.getVGPRNum(false);
+    unsigned OldAGPRRP = PressureBefore.getAGPRNum();
+    unsigned OldSGPRRP = PressureBefore.getSGPRNum();
+
+    if (NewVGPRRP > S.VGPRExcessLimit && NewVGPRRP >= OldVGPRRP)
+      return true;
+    if (NewAGPRRP > S.VGPRExcessLimit && NewAGPRRP >= OldAGPRRP)
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arsenm wrote:

ditto?

https://github.com/llvm/llvm-project/pull/68004