#include "LiveRangeEdit.h"
#include "RegAllocBase.h"
#include "Spiller.h"
+#include "SpillPlacement.h"
#include "SplitKit.h"
#include "VirtRegMap.h"
-#include "VirtRegRewriter.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Function.h"
#include "llvm/PassAnalysisSupport.h"
#include "llvm/CodeGen/CalcSpillWeights.h"
+#include "llvm/CodeGen/EdgeBundles.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/LiveStackAnalysis.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Timer.h"
+#include <queue>
+
using namespace llvm;
+STATISTIC(NumGlobalSplits, "Number of split global live ranges");
+STATISTIC(NumLocalSplits, "Number of split local live ranges");
+STATISTIC(NumReassigned, "Number of interferences reassigned");
+STATISTIC(NumEvicted, "Number of interferences evicted");
+
static RegisterRegAlloc greedyRegAlloc("greedy", "greedy register allocator",
createGreedyRegisterAllocator);
BitVector ReservedRegs;
// analyses
+ SlotIndexes *Indexes;
LiveStacks *LS;
MachineDominatorTree *DomTree;
MachineLoopInfo *Loops;
MachineLoopRanges *LoopRanges;
+ EdgeBundles *Bundles;
+ SpillPlacement *SpillPlacer;
// state
std::auto_ptr<Spiller> SpillerInstance;
std::auto_ptr<SplitAnalysis> SA;
+ std::priority_queue<std::pair<unsigned, unsigned> > Queue;
+ IndexedMap<unsigned, VirtReg2IndexFunctor> Generation;
+
+ // splitting state.
+
+ /// All basic blocks where the current register is live.
+ SmallVector<SpillPlacement::BlockConstraint, 8> SpillConstraints;
+
+ /// For every instruction in SA->UseSlots, store the previous non-copy
+ /// instruction.
+ SmallVector<SlotIndex, 8> PrevSlot;
public:
RAGreedy();
/// RAGreedy analysis usage.
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
-
virtual void releaseMemory();
-
virtual Spiller &spiller() { return *SpillerInstance; }
-
- virtual float getPriority(LiveInterval *LI);
-
- virtual unsigned selectOrSplit(LiveInterval &VirtReg,
- SmallVectorImpl<LiveInterval*> &SplitVRegs);
+ virtual void enqueue(LiveInterval *LI);
+ virtual LiveInterval *dequeue();
+ virtual unsigned selectOrSplit(LiveInterval&,
+ SmallVectorImpl<LiveInterval*>&);
/// Perform register allocation.
virtual bool runOnMachineFunction(MachineFunction &mf);
bool checkUncachedInterference(LiveInterval&, unsigned);
LiveInterval *getSingleInterference(LiveInterval&, unsigned);
bool reassignVReg(LiveInterval &InterferingVReg, unsigned OldPhysReg);
- bool reassignInterferences(LiveInterval &VirtReg, unsigned PhysReg);
- unsigned findInterferenceFreeReg(MachineLoopRange*,
- LiveInterval&, AllocationOrder&);
+ float calcInterferenceWeight(LiveInterval&, unsigned);
+ float calcInterferenceInfo(LiveInterval&, unsigned);
+ float calcGlobalSplitCost(const BitVector&);
+ void splitAroundRegion(LiveInterval&, unsigned, const BitVector&,
+ SmallVectorImpl<LiveInterval*>&);
+ void calcGapWeights(unsigned, SmallVectorImpl<float>&);
+ SlotIndex getPrevMappedIndex(const MachineInstr*);
+ void calcPrevSlots();
+ unsigned nextSplitPoint(unsigned);
+ bool canEvictInterference(LiveInterval&, unsigned, unsigned, float&);
- unsigned tryReassign(LiveInterval&, AllocationOrder&);
+ unsigned tryReassign(LiveInterval&, AllocationOrder&,
+ SmallVectorImpl<LiveInterval*>&);
+ unsigned tryEvict(LiveInterval&, AllocationOrder&,
+ SmallVectorImpl<LiveInterval*>&);
+ unsigned tryRegionSplit(LiveInterval&, AllocationOrder&,
+ SmallVectorImpl<LiveInterval*>&);
+ unsigned tryLocalSplit(LiveInterval&, AllocationOrder&,
+ SmallVectorImpl<LiveInterval*>&);
unsigned trySplit(LiveInterval&, AllocationOrder&,
SmallVectorImpl<LiveInterval*>&);
+ unsigned trySpillInterferences(LiveInterval&, AllocationOrder&,
+ SmallVectorImpl<LiveInterval*>&);
};
} // end anonymous namespace
}
RAGreedy::RAGreedy(): MachineFunctionPass(ID) {
+ initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
initializeStrongPHIEliminationPass(*PassRegistry::getPassRegistry());
initializeMachineLoopInfoPass(*PassRegistry::getPassRegistry());
initializeMachineLoopRangesPass(*PassRegistry::getPassRegistry());
initializeVirtRegMapPass(*PassRegistry::getPassRegistry());
+ initializeEdgeBundlesPass(*PassRegistry::getPassRegistry());
+ initializeSpillPlacementPass(*PassRegistry::getPassRegistry());
}
void RAGreedy::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<AliasAnalysis>();
AU.addPreserved<AliasAnalysis>();
AU.addRequired<LiveIntervals>();
+ AU.addRequired<SlotIndexes>();
AU.addPreserved<SlotIndexes>();
if (StrongPHIElim)
AU.addRequiredID(StrongPHIEliminationID);
AU.addPreserved<MachineLoopRanges>();
AU.addRequired<VirtRegMap>();
AU.addPreserved<VirtRegMap>();
+ AU.addRequired<EdgeBundles>();
+ AU.addRequired<SpillPlacement>();
MachineFunctionPass::getAnalysisUsage(AU);
}
void RAGreedy::releaseMemory() {
SpillerInstance.reset(0);
+ Generation.clear();
RegAllocBase::releaseMemory();
}
-float RAGreedy::getPriority(LiveInterval *LI) {
- float Priority = LI->weight;
+void RAGreedy::enqueue(LiveInterval *LI) {
+ // Prioritize live ranges by size, assigning larger ranges first.
+ // The queue holds (size, reg) pairs.
+ unsigned Size = LI->getSize();
+ unsigned Reg = LI->reg;
+ assert(TargetRegisterInfo::isVirtualRegister(Reg) &&
+ "Can only enqueue virtual registers");
- // Prioritize hinted registers so they are allocated first.
- std::pair<unsigned, unsigned> Hint;
- if (Hint.first || Hint.second) {
- // The hint can be target specific, a virtual register, or a physreg.
- Priority *= 2;
+ // Boost ranges that have a physical register hint.
+ unsigned Hint = VRM->getRegAllocPref(Reg);
+ if (TargetRegisterInfo::isPhysicalRegister(Hint))
+ Size |= (1u << 30);
- // Prefer physreg hints above anything else.
- if (Hint.first == 0 && TargetRegisterInfo::isPhysicalRegister(Hint.second))
- Priority *= 2;
- }
- return Priority;
+ // Boost ranges that we see for the first time.
+ Generation.grow(Reg);
+ if (++Generation[Reg] == 1)
+ Size |= (1u << 31);
+
+ Queue.push(std::make_pair(Size, Reg));
}
+LiveInterval *RAGreedy::dequeue() {
+ if (Queue.empty())
+ return 0;
+ LiveInterval *LI = &LIS->getInterval(Queue.top().second);
+ Queue.pop();
+ return LI;
+}
+
+//===----------------------------------------------------------------------===//
+// Register Reassignment
+//===----------------------------------------------------------------------===//
+
// Check interference without using the cache.
bool RAGreedy::checkUncachedInterference(LiveInterval &VirtReg,
unsigned PhysReg) {
if (Q.checkInterference()) {
if (Interference)
return 0;
- Q.collectInterferingVRegs(1);
- if (!Q.seenAllInterferences())
+ if (Q.collectInterferingVRegs(2) > 1)
return 0;
Interference = Q.interferingVRegs().front();
}
unsigned OldAssign = VRM->getPhys(InterferingVReg.reg);
DEBUG(dbgs() << "reassigning: " << InterferingVReg << " from " <<
TRI->getName(OldAssign) << " to " << TRI->getName(PhysReg) << '\n');
- PhysReg2LiveUnion[OldAssign].extract(InterferingVReg);
- VRM->clearVirt(InterferingVReg.reg);
- VRM->assignVirt2Phys(InterferingVReg.reg, PhysReg);
- PhysReg2LiveUnion[PhysReg].unify(InterferingVReg);
-
+ unassign(InterferingVReg, OldAssign);
+ assign(InterferingVReg, PhysReg);
+ ++NumReassigned;
return true;
}
return false;
}
-/// reassignInterferences - Reassign all interferences to different physical
-/// registers such that Virtreg can be assigned to PhysReg.
-/// Currently this only works with a single interference.
+/// tryReassign - Try to reassign a single interference to a different physreg.
/// @param VirtReg Currently unassigned virtual register.
-/// @param PhysReg Physical register to be cleared.
-/// @return True on success, false if nothing was changed.
-bool RAGreedy::reassignInterferences(LiveInterval &VirtReg, unsigned PhysReg) {
- LiveInterval *InterferingVReg = getSingleInterference(VirtReg, PhysReg);
- if (!InterferingVReg)
- return false;
- if (TargetRegisterInfo::isPhysicalRegister(InterferingVReg->reg))
- return false;
- return reassignVReg(*InterferingVReg, PhysReg);
+/// @param Order Physregs to try.
+/// @return Physreg to assign VirtReg, or 0.
+unsigned RAGreedy::tryReassign(LiveInterval &VirtReg, AllocationOrder &Order,
+ SmallVectorImpl<LiveInterval*> &NewVRegs){
+ NamedRegionTimer T("Reassign", TimerGroupName, TimePassesIsEnabled);
+
+ Order.rewind();
+ while (unsigned PhysReg = Order.next()) {
+ LiveInterval *InterferingVReg = getSingleInterference(VirtReg, PhysReg);
+ if (!InterferingVReg)
+ continue;
+ if (TargetRegisterInfo::isPhysicalRegister(InterferingVReg->reg))
+ continue;
+ if (reassignVReg(*InterferingVReg, PhysReg))
+ return PhysReg;
+ }
+ return 0;
}
-/// tryReassign - Try to reassign interferences to different physregs.
+
+//===----------------------------------------------------------------------===//
+// Interference eviction
+//===----------------------------------------------------------------------===//
+
+/// canEvict - Return true if all interferences between VirtReg and PhysReg can
+/// be evicted. Set maxWeight to the maximal spill weight of an interference.
+bool RAGreedy::canEvictInterference(LiveInterval &VirtReg, unsigned PhysReg,
+ unsigned Size, float &MaxWeight) {
+ float Weight = 0;
+ for (const unsigned *AliasI = TRI->getOverlaps(PhysReg); *AliasI; ++AliasI) {
+ LiveIntervalUnion::Query &Q = query(VirtReg, *AliasI);
+ // If there is 10 or more interferences, chances are one is smaller.
+ if (Q.collectInterferingVRegs(10) >= 10)
+ return false;
+
+ // CHeck if any interfering live range is shorter than VirtReg.
+ for (unsigned i = 0, e = Q.interferingVRegs().size(); i != e; ++i) {
+ LiveInterval *Intf = Q.interferingVRegs()[i];
+ if (TargetRegisterInfo::isPhysicalRegister(Intf->reg))
+ return false;
+ if (Intf->getSize() <= Size)
+ return false;
+ Weight = std::max(Weight, Intf->weight);
+ }
+ }
+ MaxWeight = Weight;
+ return true;
+}
+
+/// tryEvict - Try to evict all interferences for a physreg.
/// @param VirtReg Currently unassigned virtual register.
/// @param Order Physregs to try.
/// @return Physreg to assign VirtReg, or 0.
-unsigned RAGreedy::tryReassign(LiveInterval &VirtReg, AllocationOrder &Order) {
- NamedRegionTimer T("Reassign", TimerGroupName, TimePassesIsEnabled);
+unsigned RAGreedy::tryEvict(LiveInterval &VirtReg,
+ AllocationOrder &Order,
+ SmallVectorImpl<LiveInterval*> &NewVRegs){
+ NamedRegionTimer T("Evict", TimerGroupName, TimePassesIsEnabled);
+
+ // We can only evict interference if all interfering registers are virtual and
+ // longer than VirtReg.
+ const unsigned Size = VirtReg.getSize();
+
+ // Keep track of the lightest single interference seen so far.
+ float BestWeight = 0;
+ unsigned BestPhys = 0;
+
Order.rewind();
- while (unsigned PhysReg = Order.next())
- if (reassignInterferences(VirtReg, PhysReg))
- return PhysReg;
+ while (unsigned PhysReg = Order.next()) {
+ float Weight = 0;
+ if (!canEvictInterference(VirtReg, PhysReg, Size, Weight))
+ continue;
+
+ // This is an eviction candidate.
+ DEBUG(dbgs() << "max " << PrintReg(PhysReg, TRI) << " interference = "
+ << Weight << '\n');
+ if (BestPhys && Weight >= BestWeight)
+ continue;
+
+ // Best so far.
+ BestPhys = PhysReg;
+ BestWeight = Weight;
+ }
+
+ if (!BestPhys)
+ return 0;
+
+ DEBUG(dbgs() << "evicting " << PrintReg(BestPhys, TRI) << " interference\n");
+ for (const unsigned *AliasI = TRI->getOverlaps(BestPhys); *AliasI; ++AliasI) {
+ LiveIntervalUnion::Query &Q = query(VirtReg, *AliasI);
+ assert(Q.seenAllInterferences() && "Didn't check all interfererences.");
+ for (unsigned i = 0, e = Q.interferingVRegs().size(); i != e; ++i) {
+ LiveInterval *Intf = Q.interferingVRegs()[i];
+ unassign(*Intf, VRM->getPhys(Intf->reg));
+ ++NumEvicted;
+ NewVRegs.push_back(Intf);
+ }
+ }
+ return BestPhys;
+}
+
+
+//===----------------------------------------------------------------------===//
+// Region Splitting
+//===----------------------------------------------------------------------===//
+
+/// calcInterferenceInfo - Compute per-block outgoing and ingoing constraints
+/// when considering interference from PhysReg. Also compute an optimistic local
+/// cost of this interference pattern.
+///
+/// The final cost of a split is the local cost + global cost of preferences
+/// broken by SpillPlacement.
+///
+float RAGreedy::calcInterferenceInfo(LiveInterval &VirtReg, unsigned PhysReg) {
+ // Reset interference dependent info.
+ SpillConstraints.resize(SA->LiveBlocks.size());
+ for (unsigned i = 0, e = SA->LiveBlocks.size(); i != e; ++i) {
+ SplitAnalysis::BlockInfo &BI = SA->LiveBlocks[i];
+ SpillPlacement::BlockConstraint &BC = SpillConstraints[i];
+ BC.Number = BI.MBB->getNumber();
+ BC.Entry = (BI.Uses && BI.LiveIn) ?
+ SpillPlacement::PrefReg : SpillPlacement::DontCare;
+ BC.Exit = (BI.Uses && BI.LiveOut) ?
+ SpillPlacement::PrefReg : SpillPlacement::DontCare;
+ BI.OverlapEntry = BI.OverlapExit = false;
+ }
+
+ // Add interference info from each PhysReg alias.
+ for (const unsigned *AI = TRI->getOverlaps(PhysReg); *AI; ++AI) {
+ if (!query(VirtReg, *AI).checkInterference())
+ continue;
+ LiveIntervalUnion::SegmentIter IntI =
+ PhysReg2LiveUnion[*AI].find(VirtReg.beginIndex());
+ if (!IntI.valid())
+ continue;
+
+ // Determine which blocks have interference live in or after the last split
+ // point.
+ for (unsigned i = 0, e = SA->LiveBlocks.size(); i != e; ++i) {
+ SplitAnalysis::BlockInfo &BI = SA->LiveBlocks[i];
+ SpillPlacement::BlockConstraint &BC = SpillConstraints[i];
+ SlotIndex Start, Stop;
+ tie(Start, Stop) = Indexes->getMBBRange(BI.MBB);
+
+ // Skip interference-free blocks.
+ if (IntI.start() >= Stop)
+ continue;
+
+ // Is the interference live-in?
+ if (BI.LiveIn) {
+ IntI.advanceTo(Start);
+ if (!IntI.valid())
+ break;
+ if (IntI.start() <= Start)
+ BC.Entry = SpillPlacement::MustSpill;
+ }
+
+ // Is the interference overlapping the last split point?
+ if (BI.LiveOut) {
+ if (IntI.stop() < BI.LastSplitPoint)
+ IntI.advanceTo(BI.LastSplitPoint.getPrevSlot());
+ if (!IntI.valid())
+ break;
+ if (IntI.start() < Stop)
+ BC.Exit = SpillPlacement::MustSpill;
+ }
+ }
+
+ // Rewind iterator and check other interferences.
+ IntI.find(VirtReg.beginIndex());
+ for (unsigned i = 0, e = SA->LiveBlocks.size(); i != e; ++i) {
+ SplitAnalysis::BlockInfo &BI = SA->LiveBlocks[i];
+ SpillPlacement::BlockConstraint &BC = SpillConstraints[i];
+ SlotIndex Start, Stop;
+ tie(Start, Stop) = Indexes->getMBBRange(BI.MBB);
+
+ // Skip interference-free blocks.
+ if (IntI.start() >= Stop)
+ continue;
+
+ // Handle transparent blocks with interference separately.
+ // Transparent blocks never incur any fixed cost.
+ if (BI.LiveThrough && !BI.Uses) {
+ IntI.advanceTo(Start);
+ if (!IntI.valid())
+ break;
+ if (IntI.start() >= Stop)
+ continue;
+
+ if (BC.Entry != SpillPlacement::MustSpill)
+ BC.Entry = SpillPlacement::PrefSpill;
+ if (BC.Exit != SpillPlacement::MustSpill)
+ BC.Exit = SpillPlacement::PrefSpill;
+ continue;
+ }
+
+ // Now we only have blocks with uses left.
+ // Check if the interference overlaps the uses.
+ assert(BI.Uses && "Non-transparent block without any uses");
+
+ // Check interference on entry.
+ if (BI.LiveIn && BC.Entry != SpillPlacement::MustSpill) {
+ IntI.advanceTo(Start);
+ if (!IntI.valid())
+ break;
+ // Not live in, but before the first use.
+ if (IntI.start() < BI.FirstUse) {
+ BC.Entry = SpillPlacement::PrefSpill;
+ // If the block contains a kill from an earlier split, never split
+ // again in the same block.
+ if (!BI.LiveThrough && !SA->isOriginalEndpoint(BI.Kill))
+ BC.Entry = SpillPlacement::MustSpill;
+ }
+ }
+
+ // Does interference overlap the uses in the entry segment
+ // [FirstUse;Kill)?
+ if (BI.LiveIn && !BI.OverlapEntry) {
+ IntI.advanceTo(BI.FirstUse);
+ if (!IntI.valid())
+ break;
+ // A live-through interval has no kill.
+ // Check [FirstUse;LastUse) instead.
+ if (IntI.start() < (BI.LiveThrough ? BI.LastUse : BI.Kill))
+ BI.OverlapEntry = true;
+ }
+
+ // Does interference overlap the uses in the exit segment [Def;LastUse)?
+ if (BI.LiveOut && !BI.LiveThrough && !BI.OverlapExit) {
+ IntI.advanceTo(BI.Def);
+ if (!IntI.valid())
+ break;
+ if (IntI.start() < BI.LastUse)
+ BI.OverlapExit = true;
+ }
+
+ // Check interference on exit.
+ if (BI.LiveOut && BC.Exit != SpillPlacement::MustSpill) {
+ // Check interference between LastUse and Stop.
+ if (BC.Exit != SpillPlacement::PrefSpill) {
+ IntI.advanceTo(BI.LastUse);
+ if (!IntI.valid())
+ break;
+ if (IntI.start() < Stop) {
+ BC.Exit = SpillPlacement::PrefSpill;
+ // Avoid splitting twice in the same block.
+ if (!BI.LiveThrough && !SA->isOriginalEndpoint(BI.Def))
+ BC.Exit = SpillPlacement::MustSpill;
+ }
+ }
+ }
+ }
+ }
+
+ // Accumulate a local cost of this interference pattern.
+ float LocalCost = 0;
+ for (unsigned i = 0, e = SA->LiveBlocks.size(); i != e; ++i) {
+ SplitAnalysis::BlockInfo &BI = SA->LiveBlocks[i];
+ if (!BI.Uses)
+ continue;
+ SpillPlacement::BlockConstraint &BC = SpillConstraints[i];
+ unsigned Inserts = 0;
+
+ // Do we need spill code for the entry segment?
+ if (BI.LiveIn)
+ Inserts += BI.OverlapEntry || BC.Entry != SpillPlacement::PrefReg;
+
+ // For the exit segment?
+ if (BI.LiveOut)
+ Inserts += BI.OverlapExit || BC.Exit != SpillPlacement::PrefReg;
+
+ // The local cost of spill code in this block is the block frequency times
+ // the number of spill instructions inserted.
+ if (Inserts)
+ LocalCost += Inserts * SpillPlacer->getBlockFrequency(BI.MBB);
+ }
+ DEBUG(dbgs() << "Local cost of " << PrintReg(PhysReg, TRI) << " = "
+ << LocalCost << '\n');
+ return LocalCost;
+}
+
+/// calcGlobalSplitCost - Return the global split cost of following the split
+/// pattern in LiveBundles. This cost should be added to the local cost of the
+/// interference pattern in SpillConstraints.
+///
+float RAGreedy::calcGlobalSplitCost(const BitVector &LiveBundles) {
+ float GlobalCost = 0;
+ for (unsigned i = 0, e = SpillConstraints.size(); i != e; ++i) {
+ SpillPlacement::BlockConstraint &BC = SpillConstraints[i];
+ unsigned Inserts = 0;
+ // Broken entry preference?
+ Inserts += LiveBundles[Bundles->getBundle(BC.Number, 0)] !=
+ (BC.Entry == SpillPlacement::PrefReg);
+ // Broken exit preference?
+ Inserts += LiveBundles[Bundles->getBundle(BC.Number, 1)] !=
+ (BC.Exit == SpillPlacement::PrefReg);
+ if (Inserts)
+ GlobalCost +=
+ Inserts * SpillPlacer->getBlockFrequency(SA->LiveBlocks[i].MBB);
+ }
+ DEBUG(dbgs() << "Global cost = " << GlobalCost << '\n');
+ return GlobalCost;
+}
+
+/// splitAroundRegion - Split VirtReg around the region determined by
+/// LiveBundles. Make an effort to avoid interference from PhysReg.
+///
+/// The 'register' interval is going to contain as many uses as possible while
+/// avoiding interference. The 'stack' interval is the complement constructed by
+/// SplitEditor. It will contain the rest.
+///
+void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, unsigned PhysReg,
+ const BitVector &LiveBundles,
+ SmallVectorImpl<LiveInterval*> &NewVRegs) {
+ DEBUG({
+ dbgs() << "Splitting around region for " << PrintReg(PhysReg, TRI)
+ << " with bundles";
+ for (int i = LiveBundles.find_first(); i>=0; i = LiveBundles.find_next(i))
+ dbgs() << " EB#" << i;
+ dbgs() << ".\n";
+ });
+
+ // First compute interference ranges in the live blocks.
+ typedef std::pair<SlotIndex, SlotIndex> IndexPair;
+ SmallVector<IndexPair, 8> InterferenceRanges;
+ InterferenceRanges.resize(SA->LiveBlocks.size());
+ for (const unsigned *AI = TRI->getOverlaps(PhysReg); *AI; ++AI) {
+ if (!query(VirtReg, *AI).checkInterference())
+ continue;
+ LiveIntervalUnion::SegmentIter IntI =
+ PhysReg2LiveUnion[*AI].find(VirtReg.beginIndex());
+ if (!IntI.valid())
+ continue;
+ for (unsigned i = 0, e = SA->LiveBlocks.size(); i != e; ++i) {
+ const SplitAnalysis::BlockInfo &BI = SA->LiveBlocks[i];
+ IndexPair &IP = InterferenceRanges[i];
+ SlotIndex Start, Stop;
+ tie(Start, Stop) = Indexes->getMBBRange(BI.MBB);
+ // Skip interference-free blocks.
+ if (IntI.start() >= Stop)
+ continue;
+
+ // First interference in block.
+ if (BI.LiveIn) {
+ IntI.advanceTo(Start);
+ if (!IntI.valid())
+ break;
+ if (IntI.start() >= Stop)
+ continue;
+ if (!IP.first.isValid() || IntI.start() < IP.first)
+ IP.first = IntI.start();
+ }
+
+ // Last interference in block.
+ if (BI.LiveOut) {
+ IntI.advanceTo(Stop);
+ if (!IntI.valid() || IntI.start() >= Stop)
+ --IntI;
+ if (IntI.stop() <= Start)
+ continue;
+ if (!IP.second.isValid() || IntI.stop() > IP.second)
+ IP.second = IntI.stop();
+ }
+ }
+ }
+
+ SmallVector<LiveInterval*, 4> SpillRegs;
+ LiveRangeEdit LREdit(VirtReg, NewVRegs, SpillRegs);
+ SplitEditor SE(*SA, *LIS, *VRM, *DomTree, LREdit);
+
+ // Create the main cross-block interval.
+ SE.openIntv();
+
+ // First add all defs that are live out of a block.
+ for (unsigned i = 0, e = SA->LiveBlocks.size(); i != e; ++i) {
+ SplitAnalysis::BlockInfo &BI = SA->LiveBlocks[i];
+ bool RegIn = LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 0)];
+ bool RegOut = LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 1)];
+
+ // Should the register be live out?
+ if (!BI.LiveOut || !RegOut)
+ continue;
+
+ IndexPair &IP = InterferenceRanges[i];
+ SlotIndex Start, Stop;
+ tie(Start, Stop) = Indexes->getMBBRange(BI.MBB);
+
+ DEBUG(dbgs() << "BB#" << BI.MBB->getNumber() << " -> EB#"
+ << Bundles->getBundle(BI.MBB->getNumber(), 1)
+ << " intf [" << IP.first << ';' << IP.second << ')');
+
+ // The interference interval should either be invalid or overlap MBB.
+ assert((!IP.first.isValid() || IP.first < Stop) && "Bad interference");
+ assert((!IP.second.isValid() || IP.second > Start) && "Bad interference");
+
+ // Check interference leaving the block.
+ if (!IP.second.isValid()) {
+ // Block is interference-free.
+ DEBUG(dbgs() << ", no interference");
+ if (!BI.Uses) {
+ assert(BI.LiveThrough && "No uses, but not live through block?");
+ // Block is live-through without interference.
+ DEBUG(dbgs() << ", no uses"
+ << (RegIn ? ", live-through.\n" : ", stack in.\n"));
+ if (!RegIn)
+ SE.enterIntvAtEnd(*BI.MBB);
+ continue;
+ }
+ if (!BI.LiveThrough) {
+ DEBUG(dbgs() << ", not live-through.\n");
+ SE.useIntv(SE.enterIntvBefore(BI.Def), Stop);
+ continue;
+ }
+ if (!RegIn) {
+ // Block is live-through, but entry bundle is on the stack.
+ // Reload just before the first use.
+ DEBUG(dbgs() << ", not live-in, enter before first use.\n");
+ SE.useIntv(SE.enterIntvBefore(BI.FirstUse), Stop);
+ continue;
+ }
+ DEBUG(dbgs() << ", live-through.\n");
+ continue;
+ }
+
+ // Block has interference.
+ DEBUG(dbgs() << ", interference to " << IP.second);
+
+ if (!BI.LiveThrough && IP.second <= BI.Def) {
+ // The interference doesn't reach the outgoing segment.
+ DEBUG(dbgs() << " doesn't affect def from " << BI.Def << '\n');
+ SE.useIntv(BI.Def, Stop);
+ continue;
+ }
+
+
+ if (!BI.Uses) {
+ // No uses in block, avoid interference by reloading as late as possible.
+ DEBUG(dbgs() << ", no uses.\n");
+ SlotIndex SegStart = SE.enterIntvAtEnd(*BI.MBB);
+ assert(SegStart >= IP.second && "Couldn't avoid interference");
+ continue;
+ }
+
+ if (IP.second.getBoundaryIndex() < BI.LastUse) {
+ // There are interference-free uses at the end of the block.
+ // Find the first use that can get the live-out register.
+ SmallVectorImpl<SlotIndex>::const_iterator UI =
+ std::lower_bound(SA->UseSlots.begin(), SA->UseSlots.end(),
+ IP.second.getBoundaryIndex());
+ assert(UI != SA->UseSlots.end() && "Couldn't find last use");
+ SlotIndex Use = *UI;
+ assert(Use <= BI.LastUse && "Couldn't find last use");
+ // Only attempt a split befroe the last split point.
+ if (Use.getBaseIndex() <= BI.LastSplitPoint) {
+ DEBUG(dbgs() << ", free use at " << Use << ".\n");
+ SlotIndex SegStart = SE.enterIntvBefore(Use);
+ assert(SegStart >= IP.second && "Couldn't avoid interference");
+ assert(SegStart < BI.LastSplitPoint && "Impossible split point");
+ SE.useIntv(SegStart, Stop);
+ continue;
+ }
+ }
+
+ // Interference is after the last use.
+ DEBUG(dbgs() << " after last use.\n");
+ SlotIndex SegStart = SE.enterIntvAtEnd(*BI.MBB);
+ assert(SegStart >= IP.second && "Couldn't avoid interference");
+ }
+
+ // Now all defs leading to live bundles are handled, do everything else.
+ for (unsigned i = 0, e = SA->LiveBlocks.size(); i != e; ++i) {
+ SplitAnalysis::BlockInfo &BI = SA->LiveBlocks[i];
+ bool RegIn = LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 0)];
+ bool RegOut = LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 1)];
+
+ // Is the register live-in?
+ if (!BI.LiveIn || !RegIn)
+ continue;
+
+ // We have an incoming register. Check for interference.
+ IndexPair &IP = InterferenceRanges[i];
+ SlotIndex Start, Stop;
+ tie(Start, Stop) = Indexes->getMBBRange(BI.MBB);
+
+ DEBUG(dbgs() << "EB#" << Bundles->getBundle(BI.MBB->getNumber(), 0)
+ << " -> BB#" << BI.MBB->getNumber());
+
+ // Check interference entering the block.
+ if (!IP.first.isValid()) {
+ // Block is interference-free.
+ DEBUG(dbgs() << ", no interference");
+ if (!BI.Uses) {
+ assert(BI.LiveThrough && "No uses, but not live through block?");
+ // Block is live-through without interference.
+ if (RegOut) {
+ DEBUG(dbgs() << ", no uses, live-through.\n");
+ SE.useIntv(Start, Stop);
+ } else {
+ DEBUG(dbgs() << ", no uses, stack-out.\n");
+ SE.leaveIntvAtTop(*BI.MBB);
+ }
+ continue;
+ }
+ if (!BI.LiveThrough) {
+ DEBUG(dbgs() << ", killed in block.\n");
+ SE.useIntv(Start, SE.leaveIntvAfter(BI.Kill));
+ continue;
+ }
+ if (!RegOut) {
+ // Block is live-through, but exit bundle is on the stack.
+ // Spill immediately after the last use.
+ if (BI.LastUse < BI.LastSplitPoint) {
+ DEBUG(dbgs() << ", uses, stack-out.\n");
+ SE.useIntv(Start, SE.leaveIntvAfter(BI.LastUse));
+ continue;
+ }
+ // The last use is after the last split point, it is probably an
+ // indirect jump.
+ DEBUG(dbgs() << ", uses at " << BI.LastUse << " after split point "
+ << BI.LastSplitPoint << ", stack-out.\n");
+ SlotIndex SegEnd = SE.leaveIntvBefore(BI.LastSplitPoint);
+ SE.useIntv(Start, SegEnd);
+ // Run a double interval from the split to the last use.
+ // This makes it possible to spill the complement without affecting the
+ // indirect branch.
+ SE.overlapIntv(SegEnd, BI.LastUse);
+ continue;
+ }
+ // Register is live-through.
+ DEBUG(dbgs() << ", uses, live-through.\n");
+ SE.useIntv(Start, Stop);
+ continue;
+ }
+
+ // Block has interference.
+ DEBUG(dbgs() << ", interference from " << IP.first);
+
+ if (!BI.LiveThrough && IP.first >= BI.Kill) {
+ // The interference doesn't reach the outgoing segment.
+ DEBUG(dbgs() << " doesn't affect kill at " << BI.Kill << '\n');
+ SE.useIntv(Start, BI.Kill);
+ continue;
+ }
+
+ if (!BI.Uses) {
+ // No uses in block, avoid interference by spilling as soon as possible.
+ DEBUG(dbgs() << ", no uses.\n");
+ SlotIndex SegEnd = SE.leaveIntvAtTop(*BI.MBB);
+ assert(SegEnd <= IP.first && "Couldn't avoid interference");
+ continue;
+ }
+ if (IP.first.getBaseIndex() > BI.FirstUse) {
+ // There are interference-free uses at the beginning of the block.
+ // Find the last use that can get the register.
+ SmallVectorImpl<SlotIndex>::const_iterator UI =
+ std::lower_bound(SA->UseSlots.begin(), SA->UseSlots.end(),
+ IP.first.getBaseIndex());
+ assert(UI != SA->UseSlots.begin() && "Couldn't find first use");
+ SlotIndex Use = (--UI)->getBoundaryIndex();
+ DEBUG(dbgs() << ", free use at " << *UI << ".\n");
+ SlotIndex SegEnd = SE.leaveIntvAfter(Use);
+ assert(SegEnd <= IP.first && "Couldn't avoid interference");
+ SE.useIntv(Start, SegEnd);
+ continue;
+ }
+
+ // Interference is before the first use.
+ DEBUG(dbgs() << " before first use.\n");
+ SlotIndex SegEnd = SE.leaveIntvAtTop(*BI.MBB);
+ assert(SegEnd <= IP.first && "Couldn't avoid interference");
+ }
+
+ SE.closeIntv();
+
+ // FIXME: Should we be more aggressive about splitting the stack region into
+ // per-block segments? The current approach allows the stack region to
+ // separate into connected components. Some components may be allocatable.
+ SE.finish();
+ ++NumGlobalSplits;
+
+ if (VerifyEnabled) {
+ MF->verify(this, "After splitting live range around region");
+
+#ifndef NDEBUG
+ // Make sure that at least one of the new intervals can allocate to PhysReg.
+ // That was the whole point of splitting the live range.
+ bool found = false;
+ for (LiveRangeEdit::iterator I = LREdit.begin(), E = LREdit.end(); I != E;
+ ++I)
+ if (!checkUncachedInterference(**I, PhysReg)) {
+ found = true;
+ break;
+ }
+ assert(found && "No allocatable intervals after pointless splitting");
+#endif
+ }
+}
+
+unsigned RAGreedy::tryRegionSplit(LiveInterval &VirtReg, AllocationOrder &Order,
+ SmallVectorImpl<LiveInterval*> &NewVRegs) {
+ BitVector LiveBundles, BestBundles;
+ float BestCost = 0;
+ unsigned BestReg = 0;
+ Order.rewind();
+ while (unsigned PhysReg = Order.next()) {
+ float Cost = calcInterferenceInfo(VirtReg, PhysReg);
+ if (BestReg && Cost >= BestCost)
+ continue;
+
+ SpillPlacer->placeSpills(SpillConstraints, LiveBundles);
+ // No live bundles, defer to splitSingleBlocks().
+ if (!LiveBundles.any())
+ continue;
+
+ Cost += calcGlobalSplitCost(LiveBundles);
+ if (!BestReg || Cost < BestCost) {
+ BestReg = PhysReg;
+ BestCost = Cost;
+ BestBundles.swap(LiveBundles);
+ }
+ }
+
+ if (!BestReg)
+ return 0;
+
+ splitAroundRegion(VirtReg, BestReg, BestBundles, NewVRegs);
return 0;
}
-/// findInterferenceFreeReg - Find a physical register in Order where Loop has
-/// no interferences with VirtReg.
-unsigned RAGreedy::findInterferenceFreeReg(MachineLoopRange *Loop,
- LiveInterval &VirtReg,
- AllocationOrder &Order) {
+
+//===----------------------------------------------------------------------===//
+// Local Splitting
+//===----------------------------------------------------------------------===//
+
+
+/// calcGapWeights - Compute the maximum spill weight that needs to be evicted
+/// in order to use PhysReg between two entries in SA->UseSlots.
+///
+/// GapWeight[i] represents the gap between UseSlots[i] and UseSlots[i+1].
+///
+void RAGreedy::calcGapWeights(unsigned PhysReg,
+ SmallVectorImpl<float> &GapWeight) {
+ assert(SA->LiveBlocks.size() == 1 && "Not a local interval");
+ const SplitAnalysis::BlockInfo &BI = SA->LiveBlocks.front();
+ const SmallVectorImpl<SlotIndex> &Uses = SA->UseSlots;
+ const unsigned NumGaps = Uses.size()-1;
+
+ // Start and end points for the interference check.
+ SlotIndex StartIdx = BI.LiveIn ? BI.FirstUse.getBaseIndex() : BI.FirstUse;
+ SlotIndex StopIdx = BI.LiveOut ? BI.LastUse.getBoundaryIndex() : BI.LastUse;
+
+ GapWeight.assign(NumGaps, 0.0f);
+
+ // Add interference from each overlapping register.
+ for (const unsigned *AI = TRI->getOverlaps(PhysReg); *AI; ++AI) {
+ if (!query(const_cast<LiveInterval&>(SA->getParent()), *AI)
+ .checkInterference())
+ continue;
+
+ // We know that VirtReg is a continuous interval from FirstUse to LastUse,
+ // so we don't need InterferenceQuery.
+ //
+ // Interference that overlaps an instruction is counted in both gaps
+ // surrounding the instruction. The exception is interference before
+ // StartIdx and after StopIdx.
+ //
+ LiveIntervalUnion::SegmentIter IntI = PhysReg2LiveUnion[*AI].find(StartIdx);
+ for (unsigned Gap = 0; IntI.valid() && IntI.start() < StopIdx; ++IntI) {
+ // Skip the gaps before IntI.
+ while (Uses[Gap+1].getBoundaryIndex() < IntI.start())
+ if (++Gap == NumGaps)
+ break;
+ if (Gap == NumGaps)
+ break;
+
+ // Update the gaps covered by IntI.
+ const float weight = IntI.value()->weight;
+ for (; Gap != NumGaps; ++Gap) {
+ GapWeight[Gap] = std::max(GapWeight[Gap], weight);
+ if (Uses[Gap+1].getBaseIndex() >= IntI.stop())
+ break;
+ }
+ if (Gap == NumGaps)
+ break;
+ }
+ }
+}
+
+/// getPrevMappedIndex - Return the slot index of the last non-copy instruction
+/// before MI that has a slot index. If MI is the first mapped instruction in
+/// its block, return the block start index instead.
+///
+SlotIndex RAGreedy::getPrevMappedIndex(const MachineInstr *MI) {
+ assert(MI && "Missing MachineInstr");
+ const MachineBasicBlock *MBB = MI->getParent();
+ MachineBasicBlock::const_iterator B = MBB->begin(), I = MI;
+ while (I != B)
+ if (!(--I)->isDebugValue() && !I->isCopy())
+ return Indexes->getInstructionIndex(I);
+ return Indexes->getMBBStartIdx(MBB);
+}
+
+/// calcPrevSlots - Fill in the PrevSlot array with the index of the previous
+/// real non-copy instruction for each instruction in SA->UseSlots.
+///
+void RAGreedy::calcPrevSlots() {
+ const SmallVectorImpl<SlotIndex> &Uses = SA->UseSlots;
+ PrevSlot.clear();
+ PrevSlot.reserve(Uses.size());
+ for (unsigned i = 0, e = Uses.size(); i != e; ++i) {
+ const MachineInstr *MI = Indexes->getInstructionFromIndex(Uses[i]);
+ PrevSlot.push_back(getPrevMappedIndex(MI).getDefIndex());
+ }
+}
+
+/// nextSplitPoint - Find the next index into SA->UseSlots > i such that it may
+/// be beneficial to split before UseSlots[i].
+///
+/// 0 is always a valid split point
+unsigned RAGreedy::nextSplitPoint(unsigned i) {
+ const SmallVectorImpl<SlotIndex> &Uses = SA->UseSlots;
+ const unsigned Size = Uses.size();
+ assert(i != Size && "No split points after the end");
+ // Allow split before i when Uses[i] is not adjacent to the previous use.
+ while (++i != Size && PrevSlot[i].getBaseIndex() <= Uses[i-1].getBaseIndex())
+ ;
+ return i;
+}
+
+/// tryLocalSplit - Try to split VirtReg into smaller intervals inside its only
+/// basic block.
+///
+unsigned RAGreedy::tryLocalSplit(LiveInterval &VirtReg, AllocationOrder &Order,
+ SmallVectorImpl<LiveInterval*> &NewVRegs) {
+ assert(SA->LiveBlocks.size() == 1 && "Not a local interval");
+ const SplitAnalysis::BlockInfo &BI = SA->LiveBlocks.front();
+
+ // Note that it is possible to have an interval that is live-in or live-out
+ // while only covering a single block - A phi-def can use undef values from
+ // predecessors, and the block could be a single-block loop.
+ // We don't bother doing anything clever about such a case, we simply assume
+ // that the interval is continuous from FirstUse to LastUse. We should make
+ // sure that we don't do anything illegal to such an interval, though.
+
+ const SmallVectorImpl<SlotIndex> &Uses = SA->UseSlots;
+ if (Uses.size() <= 2)
+ return 0;
+ const unsigned NumGaps = Uses.size()-1;
+
+ DEBUG({
+ dbgs() << "tryLocalSplit: ";
+ for (unsigned i = 0, e = Uses.size(); i != e; ++i)
+ dbgs() << ' ' << SA->UseSlots[i];
+ dbgs() << '\n';
+ });
+
+ // For every use, find the previous mapped non-copy instruction.
+ // We use this to detect valid split points, and to estimate new interval
+ // sizes.
+ calcPrevSlots();
+
+ unsigned BestBefore = NumGaps;
+ unsigned BestAfter = 0;
+ float BestDiff = 0;
+
+ const float blockFreq = SpillPlacer->getBlockFrequency(BI.MBB);
+ SmallVector<float, 8> GapWeight;
+
Order.rewind();
while (unsigned PhysReg = Order.next()) {
- bool interference = false;
- for (const unsigned *AI = TRI->getOverlaps(PhysReg); *AI; ++AI) {
- if (query(VirtReg, *AI).checkLoopInterference(Loop)) {
- interference = true;
+ // Keep track of the largest spill weight that would need to be evicted in
+ // order to make use of PhysReg between UseSlots[i] and UseSlots[i+1].
+ calcGapWeights(PhysReg, GapWeight);
+
+ // Try to find the best sequence of gaps to close.
+ // The new spill weight must be larger than any gap interference.
+
+ // We will split before Uses[SplitBefore] and after Uses[SplitAfter].
+ unsigned SplitBefore = 0, SplitAfter = nextSplitPoint(1) - 1;
+
+ // MaxGap should always be max(GapWeight[SplitBefore..SplitAfter-1]).
+ // It is the spill weight that needs to be evicted.
+ float MaxGap = GapWeight[0];
+ for (unsigned i = 1; i != SplitAfter; ++i)
+ MaxGap = std::max(MaxGap, GapWeight[i]);
+
+ for (;;) {
+ // Live before/after split?
+ const bool LiveBefore = SplitBefore != 0 || BI.LiveIn;
+ const bool LiveAfter = SplitAfter != NumGaps || BI.LiveOut;
+
+ DEBUG(dbgs() << PrintReg(PhysReg, TRI) << ' '
+ << Uses[SplitBefore] << '-' << Uses[SplitAfter]
+ << " i=" << MaxGap);
+
+ // Stop before the interval gets so big we wouldn't be making progress.
+ if (!LiveBefore && !LiveAfter) {
+ DEBUG(dbgs() << " all\n");
break;
}
+ // Should the interval be extended or shrunk?
+ bool Shrink = true;
+ if (MaxGap < HUGE_VALF) {
+ // Estimate the new spill weight.
+ //
+ // Each instruction reads and writes the register, except the first
+ // instr doesn't read when !FirstLive, and the last instr doesn't write
+ // when !LastLive.
+ //
+ // We will be inserting copies before and after, so the total number of
+ // reads and writes is 2 * EstUses.
+ //
+ const unsigned EstUses = 2*(SplitAfter - SplitBefore) +
+ 2*(LiveBefore + LiveAfter);
+
+ // Try to guess the size of the new interval. This should be trivial,
+ // but the slot index of an inserted copy can be a lot smaller than the
+ // instruction it is inserted before if there are many dead indexes
+ // between them.
+ //
+ // We measure the distance from the instruction before SplitBefore to
+ // get a conservative estimate.
+ //
+ // The final distance can still be different if inserting copies
+ // triggers a slot index renumbering.
+ //
+ const float EstWeight = normalizeSpillWeight(blockFreq * EstUses,
+ PrevSlot[SplitBefore].distance(Uses[SplitAfter]));
+ // Would this split be possible to allocate?
+ // Never allocate all gaps, we wouldn't be making progress.
+ float Diff = EstWeight - MaxGap;
+ DEBUG(dbgs() << " w=" << EstWeight << " d=" << Diff);
+ if (Diff > 0) {
+ Shrink = false;
+ if (Diff > BestDiff) {
+ DEBUG(dbgs() << " (best)");
+ BestDiff = Diff;
+ BestBefore = SplitBefore;
+ BestAfter = SplitAfter;
+ }
+ }
+ }
+
+ // Try to shrink.
+ if (Shrink) {
+ SplitBefore = nextSplitPoint(SplitBefore);
+ if (SplitBefore < SplitAfter) {
+ DEBUG(dbgs() << " shrink\n");
+ // Recompute the max when necessary.
+ if (GapWeight[SplitBefore - 1] >= MaxGap) {
+ MaxGap = GapWeight[SplitBefore];
+ for (unsigned i = SplitBefore + 1; i != SplitAfter; ++i)
+ MaxGap = std::max(MaxGap, GapWeight[i]);
+ }
+ continue;
+ }
+ MaxGap = 0;
+ }
+
+ // Try to extend the interval.
+ if (SplitAfter >= NumGaps) {
+ DEBUG(dbgs() << " end\n");
+ break;
+ }
+
+ DEBUG(dbgs() << " extend\n");
+ for (unsigned e = nextSplitPoint(SplitAfter + 1) - 1;
+ SplitAfter != e; ++SplitAfter)
+ MaxGap = std::max(MaxGap, GapWeight[SplitAfter]);
+ continue;
}
- if (!interference)
- return PhysReg;
}
- // No physreg found.
+
+ // Didn't find any candidates?
+ if (BestBefore == NumGaps)
+ return 0;
+
+ DEBUG(dbgs() << "Best local split range: " << Uses[BestBefore]
+ << '-' << Uses[BestAfter] << ", " << BestDiff
+ << ", " << (BestAfter - BestBefore + 1) << " instrs\n");
+
+ SmallVector<LiveInterval*, 4> SpillRegs;
+ LiveRangeEdit LREdit(VirtReg, NewVRegs, SpillRegs);
+ SplitEditor SE(*SA, *LIS, *VRM, *DomTree, LREdit);
+
+ SE.openIntv();
+ SlotIndex SegStart = SE.enterIntvBefore(Uses[BestBefore]);
+ SlotIndex SegStop = SE.leaveIntvAfter(Uses[BestAfter]);
+ SE.useIntv(SegStart, SegStop);
+ SE.closeIntv();
+ SE.finish();
+ ++NumLocalSplits;
+
return 0;
}
+//===----------------------------------------------------------------------===//
+// Live Range Splitting
+//===----------------------------------------------------------------------===//
+
/// trySplit - Try to split VirtReg or one of its interferences, making it
/// assignable.
-/// @return Physreg when VirtReg may be assigned and/or new SplitVRegs.
+/// @return Physreg when VirtReg may be assigned and/or new NewVRegs.
unsigned RAGreedy::trySplit(LiveInterval &VirtReg, AllocationOrder &Order,
- SmallVectorImpl<LiveInterval*>&SplitVRegs) {
- NamedRegionTimer T("Splitter", TimerGroupName, TimePassesIsEnabled);
+ SmallVectorImpl<LiveInterval*>&NewVRegs) {
SA->analyze(&VirtReg);
- // Get the set of loops that have VirtReg uses and are splittable.
- SplitAnalysis::LoopPtrSet SplitLoopSet;
- SA->getSplitLoops(SplitLoopSet);
-
- // Order loops by descending area.
- SmallVector<MachineLoopRange*, 8> SplitLoops;
- for (SplitAnalysis::LoopPtrSet::const_iterator I = SplitLoopSet.begin(),
- E = SplitLoopSet.end(); I != E; ++I)
- SplitLoops.push_back(LoopRanges->getLoopRange(*I));
- array_pod_sort(SplitLoops.begin(), SplitLoops.end(),
- MachineLoopRange::byAreaDesc);
-
- // Find the first loop that is interference-free for some register in the
- // allocation order.
- MachineLoopRange *Loop = 0;
- for (unsigned i = 0, e = SplitLoops.size(); i != e; ++i) {
- if (unsigned PhysReg = findInterferenceFreeReg(SplitLoops[i],
- VirtReg, Order)) {
- (void)PhysReg;
- Loop = SplitLoops[i];
- DEBUG(dbgs() << " " << TRI->getName(PhysReg)
- << " has no interferences in " << *Loop << '\n');
- break;
- }
+ // Local intervals are handled separately.
+ if (LIS->intervalIsInOneMBB(VirtReg)) {
+ NamedRegionTimer T("Local Splitting", TimerGroupName, TimePassesIsEnabled);
+ return tryLocalSplit(VirtReg, Order, NewVRegs);
}
- if (!Loop) {
- DEBUG(dbgs() << " All candidate loops have interference.\n");
- return 0;
- }
+ NamedRegionTimer T("Global Splitting", TimerGroupName, TimePassesIsEnabled);
- // Execute the split around Loop.
- SmallVector<LiveInterval*, 4> SpillRegs;
- LiveRangeEdit LREdit(VirtReg, SplitVRegs, SpillRegs);
- SplitEditor(*SA, *LIS, *VRM, *DomTree, LREdit)
- .splitAroundLoop(Loop->getLoop());
+ // First try to split around a region spanning multiple blocks.
+ unsigned PhysReg = tryRegionSplit(VirtReg, Order, NewVRegs);
+ if (PhysReg || !NewVRegs.empty())
+ return PhysReg;
- if (VerifyEnabled)
- MF->verify(this, "After splitting live range around loop");
+ // Then isolate blocks with multiple uses.
+ SplitAnalysis::BlockPtrSet Blocks;
+ if (SA->getMultiUseBlocks(Blocks)) {
+ SmallVector<LiveInterval*, 4> SpillRegs;
+ LiveRangeEdit LREdit(VirtReg, NewVRegs, SpillRegs);
+ SplitEditor(*SA, *LIS, *VRM, *DomTree, LREdit).splitSingleBlocks(Blocks);
+ if (VerifyEnabled)
+ MF->verify(this, "After splitting live range around basic blocks");
+ }
- // We have new split regs, don't assign anything.
+ // Don't assign any physregs.
return 0;
}
-unsigned RAGreedy::selectOrSplit(LiveInterval &VirtReg,
- SmallVectorImpl<LiveInterval*> &SplitVRegs) {
- // Populate a list of physical register spill candidates.
- SmallVector<unsigned, 8> PhysRegSpillCands;
- // Check for an available register in this class.
+//===----------------------------------------------------------------------===//
+// Spilling
+//===----------------------------------------------------------------------===//
+
+/// calcInterferenceWeight - Calculate the combined spill weight of
+/// interferences when assigning VirtReg to PhysReg.
+float RAGreedy::calcInterferenceWeight(LiveInterval &VirtReg, unsigned PhysReg){
+ float Sum = 0;
+ for (const unsigned *AI = TRI->getOverlaps(PhysReg); *AI; ++AI) {
+ LiveIntervalUnion::Query &Q = query(VirtReg, *AI);
+ Q.collectInterferingVRegs();
+ if (Q.seenUnspillableVReg())
+ return HUGE_VALF;
+ for (unsigned i = 0, e = Q.interferingVRegs().size(); i != e; ++i)
+ Sum += Q.interferingVRegs()[i]->weight;
+ }
+ return Sum;
+}
+
+/// trySpillInterferences - Try to spill interfering registers instead of the
+/// current one. Only do it if the accumulated spill weight is smaller than the
+/// current spill weight.
+unsigned RAGreedy::trySpillInterferences(LiveInterval &VirtReg,
+ AllocationOrder &Order,
+ SmallVectorImpl<LiveInterval*> &NewVRegs) {
+ NamedRegionTimer T("Spill Interference", TimerGroupName, TimePassesIsEnabled);
+ unsigned BestPhys = 0;
+ float BestWeight = 0;
+
+ Order.rewind();
+ while (unsigned PhysReg = Order.next()) {
+ float Weight = calcInterferenceWeight(VirtReg, PhysReg);
+ if (Weight == HUGE_VALF || Weight >= VirtReg.weight)
+ continue;
+ if (!BestPhys || Weight < BestWeight)
+ BestPhys = PhysReg, BestWeight = Weight;
+ }
+
+ // No candidates found.
+ if (!BestPhys)
+ return 0;
+
+ // Collect all interfering registers.
+ SmallVector<LiveInterval*, 8> Spills;
+ for (const unsigned *AI = TRI->getOverlaps(BestPhys); *AI; ++AI) {
+ LiveIntervalUnion::Query &Q = query(VirtReg, *AI);
+ Spills.append(Q.interferingVRegs().begin(), Q.interferingVRegs().end());
+ for (unsigned i = 0, e = Q.interferingVRegs().size(); i != e; ++i) {
+ LiveInterval *VReg = Q.interferingVRegs()[i];
+ unassign(*VReg, *AI);
+ }
+ }
+
+ // Spill them all.
+ DEBUG(dbgs() << "spilling " << Spills.size() << " interferences with weight "
+ << BestWeight << '\n');
+ for (unsigned i = 0, e = Spills.size(); i != e; ++i)
+ spiller().spill(Spills[i], NewVRegs, Spills);
+ return BestPhys;
+}
+
+
+//===----------------------------------------------------------------------===//
+// Main Entry Point
+//===----------------------------------------------------------------------===//
+
+unsigned RAGreedy::selectOrSplit(LiveInterval &VirtReg,
+ SmallVectorImpl<LiveInterval*> &NewVRegs) {
+ // First try assigning a free register.
AllocationOrder Order(VirtReg.reg, *VRM, ReservedRegs);
while (unsigned PhysReg = Order.next()) {
- // Check interference and as a side effect, intialize queries for this
- // VirtReg and its aliases.
- unsigned InterfReg = checkPhysRegInterference(VirtReg, PhysReg);
- if (InterfReg == 0) {
- // Found an available register.
+ if (!checkPhysRegInterference(VirtReg, PhysReg))
return PhysReg;
- }
- assert(!VirtReg.empty() && "Empty VirtReg has interference");
- LiveInterval *InterferingVirtReg =
- Queries[InterfReg].firstInterference().liveUnionPos().value();
-
- // The current VirtReg must either be spillable, or one of its interferences
- // must have less spill weight.
- if (InterferingVirtReg->weight < VirtReg.weight )
- PhysRegSpillCands.push_back(PhysReg);
}
- // Try to reassign interferences.
- if (unsigned PhysReg = tryReassign(VirtReg, Order))
+ if (unsigned PhysReg = tryReassign(VirtReg, Order, NewVRegs))
return PhysReg;
+ if (unsigned PhysReg = tryEvict(VirtReg, Order, NewVRegs))
+ return PhysReg;
+
+ assert(NewVRegs.empty() && "Cannot append to existing NewVRegs");
+
// Try splitting VirtReg or interferences.
- unsigned PhysReg = trySplit(VirtReg, Order, SplitVRegs);
- if (PhysReg || !SplitVRegs.empty())
+ unsigned PhysReg = trySplit(VirtReg, Order, NewVRegs);
+ if (PhysReg || !NewVRegs.empty())
return PhysReg;
// Try to spill another interfering reg with less spill weight.
- NamedRegionTimer T("Spiller", TimerGroupName, TimePassesIsEnabled);
- //
- // FIXME: do this in two steps: (1) check for unspillable interferences while
- // accumulating spill weight; (2) spill the interferences with lowest
- // aggregate spill weight.
- for (SmallVectorImpl<unsigned>::iterator PhysRegI = PhysRegSpillCands.begin(),
- PhysRegE = PhysRegSpillCands.end(); PhysRegI != PhysRegE; ++PhysRegI) {
-
- if (!spillInterferences(VirtReg, *PhysRegI, SplitVRegs)) continue;
-
- assert(checkPhysRegInterference(VirtReg, *PhysRegI) == 0 &&
- "Interference after spill.");
- // Tell the caller to allocate to this newly freed physical register.
- return *PhysRegI;
- }
+ PhysReg = trySpillInterferences(VirtReg, Order, NewVRegs);
+ if (PhysReg)
+ return PhysReg;
- // No other spill candidates were found, so spill the current VirtReg.
- DEBUG(dbgs() << "spilling: " << VirtReg << '\n');
+ // Finally spill VirtReg itself.
+ NamedRegionTimer T("Spiller", TimerGroupName, TimePassesIsEnabled);
SmallVector<LiveInterval*, 1> pendingSpills;
-
- spiller().spill(&VirtReg, SplitVRegs, pendingSpills);
+ spiller().spill(&VirtReg, NewVRegs, pendingSpills);
// The live virtual register requesting allocation was spilled, so tell
// the caller not to allocate anything during this round.
MF->verify(this, "Before greedy register allocator");
RegAllocBase::init(getAnalysis<VirtRegMap>(), getAnalysis<LiveIntervals>());
+ Indexes = &getAnalysis<SlotIndexes>();
DomTree = &getAnalysis<MachineDominatorTree>();
ReservedRegs = TRI->getReservedRegs(*MF);
SpillerInstance.reset(createInlineSpiller(*this, *MF, *VRM));
Loops = &getAnalysis<MachineLoopInfo>();
LoopRanges = &getAnalysis<MachineLoopRanges>();
- SA.reset(new SplitAnalysis(*MF, *LIS, *Loops));
+ Bundles = &getAnalysis<EdgeBundles>();
+ SpillPlacer = &getAnalysis<SpillPlacement>();
+
+ SA.reset(new SplitAnalysis(*VRM, *LIS, *Loops));
allocatePhysRegs();
addMBBLiveIns(MF);
+ LIS->addKillFlags();
// Run rewriter
{
NamedRegionTimer T("Rewriter", TimerGroupName, TimePassesIsEnabled);
- std::auto_ptr<VirtRegRewriter> rewriter(createVirtRegRewriter());
- rewriter->runOnMachineFunction(*MF, *VRM, LIS);
+ VRM->rewrite(Indexes);
}
// The pass output is in VirtRegMap. Release all the transient data.
projects / oota-llvm.git / blobdiff