[AMDGPU] Small refactoring in the scheduler

[rampitec]

Summary

After last changes some code can be simplified.

llvm/trunk/lib/Target/AMDGPU/GCNSchedStrategy.cpp

 #define DEBUG_TYPE "machine-scheduler"
 
 using namespace llvm;
 
 GCNMaxOccupancySchedStrategy::GCNMaxOccupancySchedStrategy(
     const MachineSchedContext *C) :
     GenericScheduler(C), TargetOccupancy(0), MF(nullptr) { }
 
-static unsigned getMaxWaves(unsigned SGPRs, unsigned VGPRs,
-                            const MachineFunction &MF) {
-
-  const SISubtarget &ST = MF.getSubtarget<SISubtarget>();
-  const SIMachineFunctionInfo *MFI = MF.getInfo<SIMachineFunctionInfo>();
-  unsigned MinRegOccupancy = std::min(ST.getOccupancyWithNumSGPRs(SGPRs),
-                                      ST.getOccupancyWithNumVGPRs(VGPRs));
-  return std::min(MinRegOccupancy,
-                  ST.getOccupancyWithLocalMemSize(MFI->getLDSSize(),
-                                                  MF.getFunction()));
-}
-
 void GCNMaxOccupancySchedStrategy::initialize(ScheduleDAGMI *DAG) {
   GenericScheduler::initialize(DAG);
 
   const SIRegisterInfo *SRI = static_cast<const SIRegisterInfo*>(TRI);
 
   MF = &DAG->MF;
 
   const SISubtarget &ST = MF->getSubtarget<SISubtarget>();
LLVM_DEBUG(dbgs() << "Pressure after scheduling: ";
              PressureAfter.print(dbgs()));
 
   if (PressureAfter.getSGPRNum() <= S.SGPRCriticalLimit &&
       PressureAfter.getVGPRNum() <= S.VGPRCriticalLimit) {
     Pressure[RegionIdx] = PressureAfter;
     LLVM_DEBUG(dbgs() << "Pressure in desired limits, done.\n");
     return;
   }
-  unsigned WavesAfter = getMaxWaves(PressureAfter.getSGPRNum(),
-                                    PressureAfter.getVGPRNum(), MF);
-  unsigned WavesBefore = getMaxWaves(PressureBefore.getSGPRNum(),
-                                     PressureBefore.getVGPRNum(), MF);
-  WavesAfter = std::min(WavesAfter, MFI.getMaxWavesPerEU());
-  WavesBefore = std::min(WavesBefore, MFI.getMaxWavesPerEU());
+  unsigned Occ = MFI.getOccupancy();
+  unsigned WavesAfter = std::min(Occ, PressureAfter.getOccupancy(ST));
+  unsigned WavesBefore = std::min(Occ, PressureBefore.getOccupancy(ST));
   LLVM_DEBUG(dbgs() << "Occupancy before scheduling: " << WavesBefore
                     << ", after " << WavesAfter << ".\n");
 
   // We could not keep current target occupancy because of the just scheduled
   // region. Record new occupancy for next scheduling cycle.
   unsigned NewOccupancy = std::max(WavesAfter, WavesBefore);
   // Allow memory bound functions to drop to 4 waves if not limited by an
   // attribute.