[llvm] [AMDGPU] Optionally Use GCNRPTrackers during scheduling (PR #93090)

[Valery Pykhtin via llvm-commits]

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@@ -128,23 +134,46 @@ void GCNSchedStrategy::initCandidate(SchedCandidate &Cand, SUnit *SU,
   if (!DAG->isTrackingPressure())
     return;
 
-  // getDownwardPressure() and getUpwardPressure() make temporary changes to
-  // the tracker, so we need to pass those function a non-const copy.
-  RegPressureTracker &TempTracker = const_cast<RegPressureTracker&>(RPTracker);
+  unsigned NewSGPRPressure, NewVGPRPressure;
+  if (!GCNTrackers) {
+    // getDownwardPressure() and getUpwardPressure() make temporary changes to
+    // the tracker, so we need to pass those function a non-const copy.
+    RegPressureTracker &TempTracker =
+        const_cast<RegPressureTracker &>(RPTracker);
+
+    Pressure.clear();
+    MaxPressure.clear();
+
+    if (AtTop)
+      TempTracker.getDownwardPressure(SU->getInstr(), Pressure, MaxPressure);
+    else {
+      // FIXME: I think for bottom up scheduling, the register pressure is
+      // cached and can be retrieved by DAG->getPressureDif(SU).
+      TempTracker.getUpwardPressure(SU->getInstr(), Pressure, MaxPressure);
+    }
+    NewSGPRPressure = Pressure[AMDGPU::RegisterPressureSets::SReg_32];
+    NewVGPRPressure = Pressure[AMDGPU::RegisterPressureSets::VGPR_32];
+  }
 
-  Pressure.clear();
-  MaxPressure.clear();
+  if (GCNTrackers) {
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vpykhtin wrote:

"else" from if at 138 line?

https://github.com/llvm/llvm-project/pull/93090