vendor/llvm/llvm-trunk-r303197

1 files changed, 134 insertions, 148 deletions

diff --git a/lib/Target/AMDGPU/GCNSchedStrategy.cpp b/lib/Target/AMDGPU/GCNSchedStrategy.cpp
index 630442625aa3..8ec46665daf5 100644
--- a/lib/Target/AMDGPU/GCNSchedStrategy.cpp
+++ b/lib/Target/AMDGPU/GCNSchedStrategy.cpp
@@ -316,46 +316,57 @@ GCNScheduleDAGMILive::GCNScheduleDAGMILive(MachineSchedContext *C,
   MFI(*MF.getInfo<SIMachineFunctionInfo>()),
   StartingOccupancy(ST.getOccupancyWithLocalMemSize(MFI.getLDSSize(),
                                                     *MF.getFunction())),
-  MinOccupancy(StartingOccupancy), Stage(0) {
+  MinOccupancy(StartingOccupancy), Stage(0), RegionIdx(0) {
 
   DEBUG(dbgs() << "Starting occupancy is " << StartingOccupancy << ".\n");
 }
 
 void GCNScheduleDAGMILive::schedule() {
+  if (Stage == 0) {
+    // Just record regions at the first pass.
+    Regions.push_back(std::make_pair(RegionBegin, RegionEnd));
+    return;
+  }
+
   std::vector<MachineInstr*> Unsched;
   Unsched.reserve(NumRegionInstrs);
   for (auto &I : *this)
     Unsched.push_back(&I);
 
-  std::pair<unsigned, unsigned> PressureBefore;
+  GCNRegPressure PressureBefore;
   if (LIS) {
-    DEBUG(dbgs() << "Pressure before scheduling:\n");
-    discoverLiveIns();
-    PressureBefore = getRealRegPressure();
+    PressureBefore = Pressure[RegionIdx];
+
+    DEBUG(dbgs() << "Pressure before scheduling:\nRegion live-ins:";
+          GCNRPTracker::printLiveRegs(dbgs(), LiveIns[RegionIdx], MRI);
+          dbgs() << "Region live-in pressure:  ";
+          llvm::getRegPressure(MRI, LiveIns[RegionIdx]).print(dbgs());
+          dbgs() << "Region register pressure: ";
+          PressureBefore.print(dbgs()));
   }
 
   ScheduleDAGMILive::schedule();
-  if (Stage == 0)
-    Regions.push_back(std::make_pair(RegionBegin, RegionEnd));
+  Regions[RegionIdx] = std::make_pair(RegionBegin, RegionEnd);
 
   if (!LIS)
     return;
 
   // Check the results of scheduling.
   GCNMaxOccupancySchedStrategy &S = (GCNMaxOccupancySchedStrategy&)*SchedImpl;
-  DEBUG(dbgs() << "Pressure after scheduling:\n");
   auto PressureAfter = getRealRegPressure();
-  LiveIns.clear();
 
-  if (PressureAfter.first <= S.SGPRCriticalLimit &&
-      PressureAfter.second <= S.VGPRCriticalLimit) {
+  DEBUG(dbgs() << "Pressure after scheduling: "; PressureAfter.print(dbgs()));
+
+  if (PressureAfter.getSGPRNum() <= S.SGPRCriticalLimit &&
+      PressureAfter.getVGPRNum() <= S.VGPRCriticalLimit) {
+    Pressure[RegionIdx] = PressureAfter;
     DEBUG(dbgs() << "Pressure in desired limits, done.\n");
     return;
   }
-  unsigned WavesAfter = getMaxWaves(PressureAfter.first,
-                                    PressureAfter.second, MF);
-  unsigned WavesBefore = getMaxWaves(PressureBefore.first,
-                                      PressureBefore.second, MF);
+  unsigned WavesAfter = getMaxWaves(PressureAfter.getSGPRNum(),
+                                    PressureAfter.getVGPRNum(), MF);
+  unsigned WavesBefore = getMaxWaves(PressureBefore.getSGPRNum(),
+                                     PressureBefore.getVGPRNum(), MF);
   DEBUG(dbgs() << "Occupancy before scheduling: " << WavesBefore <<
                   ", after " << WavesAfter << ".\n");
 
@@ -368,8 +379,10 @@ void GCNScheduleDAGMILive::schedule() {
                  << MinOccupancy << ".\n");
   }
 
-  if (WavesAfter >= WavesBefore)
+  if (WavesAfter >= WavesBefore) {
+    Pressure[RegionIdx] = PressureAfter;
     return;
+  }
 
   DEBUG(dbgs() << "Attempting to revert scheduling.\n");
   RegionEnd = RegionBegin;
@@ -398,166 +411,139 @@ void GCNScheduleDAGMILive::schedule() {
     DEBUG(dbgs() << "Scheduling " << *MI);
   }
   RegionBegin = Unsched.front()->getIterator();
-  if (Stage == 0)
-    Regions.back() = std::make_pair(RegionBegin, RegionEnd);
+  Regions[RegionIdx] = std::make_pair(RegionBegin, RegionEnd);
 
   placeDebugValues();
 }
 
-static inline void setMask(const MachineRegisterInfo &MRI,
-                           const SIRegisterInfo *SRI, unsigned Reg,
-                           LaneBitmask &PrevMask, LaneBitmask NewMask,
-                           unsigned &SGPRs, unsigned &VGPRs) {
-  int NewRegs = countPopulation(NewMask.getAsInteger()) -
-                countPopulation(PrevMask.getAsInteger());
-  if (SRI->isSGPRReg(MRI, Reg))
-    SGPRs += NewRegs;
-  if (SRI->isVGPR(MRI, Reg))
-    VGPRs += NewRegs;
-  assert ((int)SGPRs >= 0 && (int)VGPRs >= 0);
-  PrevMask = NewMask;
+GCNRegPressure GCNScheduleDAGMILive::getRealRegPressure() const {
+  GCNDownwardRPTracker RPTracker(*LIS);
+  RPTracker.advance(begin(), end(), &LiveIns[RegionIdx]);
+  return RPTracker.moveMaxPressure();
 }
 
-void GCNScheduleDAGMILive::discoverLiveIns() {
-  unsigned SGPRs = 0;
-  unsigned VGPRs = 0;
+void GCNScheduleDAGMILive::computeBlockPressure(const MachineBasicBlock *MBB) {
+  GCNDownwardRPTracker RPTracker(*LIS);
+
+  // If the block has the only successor then live-ins of that successor are
+  // live-outs of the current block. We can reuse calculated live set if the
+  // successor will be sent to scheduling past current block.
+  const MachineBasicBlock *OnlySucc = nullptr;
+  if (MBB->succ_size() == 1 && !(*MBB->succ_begin())->empty()) {
+    SlotIndexes *Ind = LIS->getSlotIndexes();
+    if (Ind->getMBBStartIdx(MBB) < Ind->getMBBStartIdx(*MBB->succ_begin()))
+      OnlySucc = *MBB->succ_begin();
+  }
 
-  auto &MI = *begin()->getParent()->getFirstNonDebugInstr();
-  const SIRegisterInfo *SRI = static_cast<const SIRegisterInfo*>(TRI);
-  SlotIndex SI = LIS->getInstructionIndex(MI).getBaseIndex();
-  assert (SI.isValid());
-
-  DEBUG(dbgs() << "Region live-ins:");
-  for (unsigned I = 0, E = MRI.getNumVirtRegs(); I != E; ++I) {
-    unsigned Reg = TargetRegisterInfo::index2VirtReg(I);
-    if (MRI.reg_nodbg_empty(Reg))
-      continue;
-    const LiveInterval &LI = LIS->getInterval(Reg);
-    LaneBitmask LaneMask = LaneBitmask::getNone();
-    if (LI.hasSubRanges()) {
-      for (const auto &S : LI.subranges())
-        if (S.liveAt(SI))
-          LaneMask |= S.LaneMask;
-    } else if (LI.liveAt(SI)) {
-      LaneMask = MRI.getMaxLaneMaskForVReg(Reg);
-    }
+  // Scheduler sends regions from the end of the block upwards.
+  size_t CurRegion = RegionIdx;
+  for (size_t E = Regions.size(); CurRegion != E; ++CurRegion)
+    if (Regions[CurRegion].first->getParent() != MBB)
+      break;
+  --CurRegion;
+
+  auto I = MBB->begin();
+  auto LiveInIt = MBBLiveIns.find(MBB);
+  if (LiveInIt != MBBLiveIns.end()) {
+    auto LiveIn = std::move(LiveInIt->second);
+    RPTracker.reset(*MBB->begin(), &LiveIn);
+    MBBLiveIns.erase(LiveInIt);
+  } else {
+    I = Regions[CurRegion].first;
+    RPTracker.reset(*I);
+  }
 
-    if (LaneMask.any()) {
-      setMask(MRI, SRI, Reg, LiveIns[Reg], LaneMask, SGPRs, VGPRs);
+  for ( ; ; ) {
+    I = RPTracker.getNext();
 
-      DEBUG(dbgs() << ' ' << PrintVRegOrUnit(Reg, SRI) << ':'
-                   << PrintLaneMask(LiveIns[Reg]));
+    if (Regions[CurRegion].first == I) {
+      LiveIns[CurRegion] = RPTracker.getLiveRegs();
+      RPTracker.clearMaxPressure();
     }
-  }
 
-  LiveInPressure = std::make_pair(SGPRs, VGPRs);
+    if (Regions[CurRegion].second == I) {
+      Pressure[CurRegion] = RPTracker.moveMaxPressure();
+      if (CurRegion-- == RegionIdx)
+        break;
+    }
+    RPTracker.advanceToNext();
+    RPTracker.advanceBeforeNext();
+  }
 
-  DEBUG(dbgs() << "\nLive-in pressure:\nSGPR = " << SGPRs
-               << "\nVGPR = " << VGPRs << '\n');
+  if (OnlySucc) {
+    if (I != MBB->end()) {
+      RPTracker.advanceToNext();
+      RPTracker.advance(MBB->end());
+    }
+    RPTracker.reset(*OnlySucc->begin(), &RPTracker.getLiveRegs());
+    RPTracker.advanceBeforeNext();
+    MBBLiveIns[OnlySucc] = RPTracker.moveLiveRegs();
+  }
 }
 
-std::pair<unsigned, unsigned>
-GCNScheduleDAGMILive::getRealRegPressure() const {
-  unsigned SGPRs, MaxSGPRs, VGPRs, MaxVGPRs;
-  SGPRs = MaxSGPRs = LiveInPressure.first;
-  VGPRs = MaxVGPRs = LiveInPressure.second;
-
-  const SIRegisterInfo *SRI = static_cast<const SIRegisterInfo*>(TRI);
-  DenseMap<unsigned, LaneBitmask> LiveRegs(LiveIns);
+void GCNScheduleDAGMILive::finalizeSchedule() {
+  GCNMaxOccupancySchedStrategy &S = (GCNMaxOccupancySchedStrategy&)*SchedImpl;
+  DEBUG(dbgs() << "All regions recorded, starting actual scheduling.\n");
 
-  for (const MachineInstr &MI : *this) {
-    if (MI.isDebugValue())
-      continue;
-    SlotIndex SI = LIS->getInstructionIndex(MI).getBaseIndex();
-    assert (SI.isValid());
+  LiveIns.resize(Regions.size());
+  Pressure.resize(Regions.size());
 
-    // Remove dead registers or mask bits.
-    for (auto &It : LiveRegs) {
-      if (It.second.none())
-        continue;
-      const LiveInterval &LI = LIS->getInterval(It.first);
-      if (LI.hasSubRanges()) {
-        for (const auto &S : LI.subranges())
-          if (!S.liveAt(SI))
-            setMask(MRI, SRI, It.first, It.second, It.second & ~S.LaneMask,
-                    SGPRs, VGPRs);
-      } else if (!LI.liveAt(SI)) {
-        setMask(MRI, SRI, It.first, It.second, LaneBitmask::getNone(),
-                SGPRs, VGPRs);
-      }
-    }
+  do {
+    Stage++;
+    RegionIdx = 0;
+    MachineBasicBlock *MBB = nullptr;
 
-    // Add new registers or mask bits.
-    for (const auto &MO : MI.defs()) {
-      if (!MO.isReg())
-        continue;
-      unsigned Reg = MO.getReg();
-      if (!TargetRegisterInfo::isVirtualRegister(Reg))
-        continue;
-      unsigned SubRegIdx = MO.getSubReg();
-      LaneBitmask LaneMask = SubRegIdx != 0
-                             ? TRI->getSubRegIndexLaneMask(SubRegIdx)
-                             : MRI.getMaxLaneMaskForVReg(Reg);
-      LaneBitmask &LM = LiveRegs[Reg];
-      setMask(MRI, SRI, Reg, LM, LM | LaneMask, SGPRs, VGPRs);
-    }
-    MaxSGPRs = std::max(MaxSGPRs, SGPRs);
-    MaxVGPRs = std::max(MaxVGPRs, VGPRs);
-  }
+    if (Stage > 1) {
+      // Retry function scheduling if we found resulting occupancy and it is
+      // lower than used for first pass scheduling. This will give more freedom
+      // to schedule low register pressure blocks.
+      // Code is partially copied from MachineSchedulerBase::scheduleRegions().
 
-  DEBUG(dbgs() << "Real region's register pressure:\nSGPR = " << MaxSGPRs
-               << "\nVGPR = " << MaxVGPRs << '\n');
+      if (!LIS || StartingOccupancy <= MinOccupancy)
+        break;
 
-  return std::make_pair(MaxSGPRs, MaxVGPRs);
-}
+      DEBUG(dbgs()
+              << "Retrying function scheduling with lowest recorded occupancy "
+              << MinOccupancy << ".\n");
 
-void GCNScheduleDAGMILive::finalizeSchedule() {
-  // Retry function scheduling if we found resulting occupancy and it is
-  // lower than used for first pass scheduling. This will give more freedom
-  // to schedule low register pressure blocks.
-  // Code is partially copied from MachineSchedulerBase::scheduleRegions().
+      S.setTargetOccupancy(MinOccupancy);
+    }
 
-  if (!LIS || StartingOccupancy <= MinOccupancy)
-    return;
+    for (auto Region : Regions) {
+      RegionBegin = Region.first;
+      RegionEnd = Region.second;
 
-  DEBUG(dbgs() << "Retrying function scheduling with lowest recorded occupancy "
-               << MinOccupancy << ".\n");
+      if (RegionBegin->getParent() != MBB) {
+        if (MBB) finishBlock();
+        MBB = RegionBegin->getParent();
+        startBlock(MBB);
+        if (Stage == 1)
+          computeBlockPressure(MBB);
+      }
 
-  Stage++;
-  GCNMaxOccupancySchedStrategy &S = (GCNMaxOccupancySchedStrategy&)*SchedImpl;
-  S.setTargetOccupancy(MinOccupancy);
+      unsigned NumRegionInstrs = std::distance(begin(), end());
+      enterRegion(MBB, begin(), end(), NumRegionInstrs);
 
-  MachineBasicBlock *MBB = nullptr;
-  for (auto Region : Regions) {
-    RegionBegin = Region.first;
-    RegionEnd = Region.second;
+      // Skip empty scheduling regions (0 or 1 schedulable instructions).
+      if (begin() == end() || begin() == std::prev(end())) {
+        exitRegion();
+        continue;
+      }
 
-    if (RegionBegin->getParent() != MBB) {
-      if (MBB) finishBlock();
-      MBB = RegionBegin->getParent();
-      startBlock(MBB);
-    }
+      DEBUG(dbgs() << "********** MI Scheduling **********\n");
+      DEBUG(dbgs() << MF.getName()
+            << ":BB#" << MBB->getNumber() << " " << MBB->getName()
+            << "\n  From: " << *begin() << "    To: ";
+            if (RegionEnd != MBB->end()) dbgs() << *RegionEnd;
+            else dbgs() << "End";
+            dbgs() << " RegionInstrs: " << NumRegionInstrs << '\n');
 
-    unsigned NumRegionInstrs = std::distance(begin(), end());
-    enterRegion(MBB, begin(), end(), NumRegionInstrs);
+      schedule();
 
-    // Skip empty scheduling regions (0 or 1 schedulable instructions).
-    if (begin() == end() || begin() == std::prev(end())) {
       exitRegion();
-      continue;
+      ++RegionIdx;
     }
-    DEBUG(dbgs() << "********** MI Scheduling **********\n");
-    DEBUG(dbgs() << MF.getName()
-          << ":BB#" << MBB->getNumber() << " " << MBB->getName()
-          << "\n  From: " << *begin() << "    To: ";
-          if (RegionEnd != MBB->end()) dbgs() << *RegionEnd;
-          else dbgs() << "End";
-          dbgs() << " RegionInstrs: " << NumRegionInstrs << '\n');
+    finishBlock();
 
-    schedule();
-
-    exitRegion();
-  }
-  finishBlock();
-  LiveIns.shrink_and_clear();
+  } while (Stage < 2);
 }