#include "AllocationOrder.h"
#include "InterferenceCache.h"
#include "LiveDebugVariables.h"
-#include "LiveRangeEdit.h"
#include "RegAllocBase.h"
#include "Spiller.h"
#include "SpillPlacement.h"
#include "SplitKit.h"
#include "VirtRegMap.h"
-#include "RegisterCoalescer.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/EdgeBundles.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "llvm/CodeGen/LiveRangeEdit.h"
#include "llvm/CodeGen/LiveStackAnalysis.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/RegAllocRegistry.h"
#include "llvm/Target/TargetOptions.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
STATISTIC(NumLocalSplits, "Number of split local live ranges");
STATISTIC(NumEvicted, "Number of interferences evicted");
+static cl::opt<SplitEditor::ComplementSpillMode>
+SplitSpillMode("split-spill-mode", cl::Hidden,
+ cl::desc("Spill mode for splitting live ranges"),
+ cl::values(clEnumValN(SplitEditor::SM_Partition, "default", "Default"),
+ clEnumValN(SplitEditor::SM_Size, "size", "Optimize for size"),
+ clEnumValN(SplitEditor::SM_Speed, "speed", "Optimize for speed"),
+ clEnumValEnd),
+ cl::init(SplitEditor::SM_Partition));
+
static RegisterRegAlloc greedyRegAlloc("greedy", "greedy register allocator",
createGreedyRegisterAllocator);
}
};
+ // Register mask interference. The current VirtReg is checked for register
+ // mask interference on entry to selectOrSplit(). If there is no
+ // interference, UsableRegs is left empty. If there is interference,
+ // UsableRegs has a bit mask of registers that can be used without register
+ // mask interference.
+ BitVector UsableRegs;
+
+ /// clobberedByRegMask - Returns true if PhysReg is not directly usable
+ /// because of register mask clobbers.
+ bool clobberedByRegMask(unsigned PhysReg) const {
+ return !UsableRegs.empty() && !UsableRegs.test(PhysReg);
+ }
+
// splitting state.
std::auto_ptr<SplitAnalysis> SA;
std::auto_ptr<SplitEditor> SE;
/// Global live range splitting candidate info.
struct GlobalSplitCandidate {
+ // Register intended for assignment, or 0.
unsigned PhysReg;
+
+ // SplitKit interval index for this candidate.
+ unsigned IntvIdx;
+
+ // Interference for PhysReg.
InterferenceCache::Cursor Intf;
+
+ // Bundles where this candidate should be live.
BitVector LiveBundles;
SmallVector<unsigned, 8> ActiveBlocks;
void reset(InterferenceCache &Cache, unsigned Reg) {
PhysReg = Reg;
+ IntvIdx = 0;
Intf.setPhysReg(Cache, Reg);
LiveBundles.clear();
ActiveBlocks.clear();
}
+
+ // Set B[i] = C for every live bundle where B[i] was NoCand.
+ unsigned getBundles(SmallVectorImpl<unsigned> &B, unsigned C) {
+ unsigned Count = 0;
+ for (int i = LiveBundles.find_first(); i >= 0;
+ i = LiveBundles.find_next(i))
+ if (B[i] == NoCand) {
+ B[i] = C;
+ Count++;
+ }
+ return Count;
+ }
};
/// Candidate info for for each PhysReg in AllocationOrder.
/// class.
SmallVector<GlobalSplitCandidate, 32> GlobalCand;
+ enum { NoCand = ~0u };
+
+ /// Candidate map. Each edge bundle is assigned to a GlobalCand entry, or to
+ /// NoCand which indicates the stack interval.
+ SmallVector<unsigned, 32> BundleCand;
+
public:
RAGreedy();
static char ID;
private:
- void LRE_WillEraseInstruction(MachineInstr*);
bool LRE_CanEraseVirtReg(unsigned);
void LRE_WillShrinkVirtReg(unsigned);
void LRE_DidCloneVirtReg(unsigned, unsigned);
void growRegion(GlobalSplitCandidate &Cand);
float calcGlobalSplitCost(GlobalSplitCandidate&);
bool calcCompactRegion(GlobalSplitCandidate&);
- void splitAroundRegion(LiveInterval&, GlobalSplitCandidate&,
- SmallVectorImpl<LiveInterval*>&);
+ void splitAroundRegion(LiveRangeEdit&, ArrayRef<unsigned>);
void calcGapWeights(unsigned, SmallVectorImpl<float>&);
bool shouldEvict(LiveInterval &A, bool, LiveInterval &B, bool);
bool canEvictInterference(LiveInterval&, unsigned, bool, EvictionCost&);
SmallVectorImpl<LiveInterval*>&, unsigned = ~0u);
unsigned tryRegionSplit(LiveInterval&, AllocationOrder&,
SmallVectorImpl<LiveInterval*>&);
+ unsigned tryBlockSplit(LiveInterval&, AllocationOrder&,
+ SmallVectorImpl<LiveInterval*>&);
+ unsigned tryInstructionSplit(LiveInterval&, AllocationOrder&,
+ SmallVectorImpl<LiveInterval*>&);
unsigned tryLocalSplit(LiveInterval&, AllocationOrder&,
SmallVectorImpl<LiveInterval*>&);
unsigned trySplit(LiveInterval&, AllocationOrder&,
initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
- initializeStrongPHIEliminationPass(*PassRegistry::getPassRegistry());
initializeRegisterCoalescerPass(*PassRegistry::getPassRegistry());
+ initializeMachineSchedulerPass(*PassRegistry::getPassRegistry());
initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
initializeLiveStacksPass(*PassRegistry::getPassRegistry());
initializeMachineDominatorTreePass(*PassRegistry::getPassRegistry());
AU.addPreserved<SlotIndexes>();
AU.addRequired<LiveDebugVariables>();
AU.addPreserved<LiveDebugVariables>();
- if (StrongPHIElim)
- AU.addRequiredID(StrongPHIEliminationID);
- AU.addRequiredTransitive<RegisterCoalescer>();
AU.addRequired<CalculateSpillWeights>();
AU.addRequired<LiveStacks>();
AU.addPreserved<LiveStacks>();
// LiveRangeEdit delegate methods
//===----------------------------------------------------------------------===//
-void RAGreedy::LRE_WillEraseInstruction(MachineInstr *MI) {
- // LRE itself will remove from SlotIndexes and parent basic block.
- VRM->RemoveMachineInstrFromMaps(MI);
-}
-
bool RAGreedy::LRE_CanEraseVirtReg(unsigned VirtReg) {
if (unsigned PhysReg = VRM->getPhys(VirtReg)) {
unassign(LIS->getInterval(VirtReg), PhysReg);
}
void RAGreedy::LRE_DidCloneVirtReg(unsigned New, unsigned Old) {
+ // Cloning a register we haven't even heard about yet? Just ignore it.
+ if (!ExtraRegInfo.inBounds(Old))
+ return;
+
// LRE may clone a virtual register because dead code elimination causes it to
- // be split into connected components. Ensure that the new register gets the
+ // be split into connected components. The new components are much smaller
+ // than the original, so they should get a new chance at being assigned.
// same stage as the parent.
+ ExtraRegInfo[Old].Stage = RS_Assign;
ExtraRegInfo.grow(New);
ExtraRegInfo[New] = ExtraRegInfo[Old];
}
if (ExtraRegInfo[Reg].Stage == RS_New)
ExtraRegInfo[Reg].Stage = RS_Assign;
- if (ExtraRegInfo[Reg].Stage == RS_Split)
+ if (ExtraRegInfo[Reg].Stage == RS_Split) {
// Unsplit ranges that couldn't be allocated immediately are deferred until
- // everything else has been allocated. Long ranges are allocated last so
- // they are split against realistic interference.
- Prio = (1u << 31) - Size;
- else {
- // Everything else is allocated in long->short order. Long ranges that don't
- // fit should be spilled ASAP so they don't create interference.
+ // everything else has been allocated.
+ Prio = Size;
+ } else {
+ // Everything is allocated in long->short order. Long ranges that don't fit
+ // should be spilled (or split) ASAP so they don't create interference.
Prio = (1u << 31) + Size;
// Boost ranges that have a physical register hint.
Prio |= (1u << 30);
}
- Queue.push(std::make_pair(Prio, Reg));
+ Queue.push(std::make_pair(Prio, ~Reg));
}
LiveInterval *RAGreedy::dequeue() {
if (Queue.empty())
return 0;
- LiveInterval *LI = &LIS->getInterval(Queue.top().second);
+ LiveInterval *LI = &LIS->getInterval(~Queue.top().second);
Queue.pop();
return LI;
}
SmallVectorImpl<LiveInterval*> &NewVRegs) {
Order.rewind();
unsigned PhysReg;
- while ((PhysReg = Order.next()))
+ while ((PhysReg = Order.next())) {
+ if (clobberedByRegMask(PhysReg))
+ continue;
if (!checkPhysRegInterference(VirtReg, PhysReg))
break;
+ }
if (!PhysReg || Order.isHint(PhysReg))
return PhysReg;
// If we missed a simple hint, try to cheaply evict interference from the
// preferred register.
if (unsigned Hint = MRI->getSimpleHint(VirtReg.reg))
- if (Order.isHint(Hint)) {
+ if (Order.isHint(Hint) && !clobberedByRegMask(Hint)) {
DEBUG(dbgs() << "missed hint " << PrintReg(Hint, TRI) << '\n');
EvictionCost MaxCost(1);
if (canEvictInterference(VirtReg, Hint, true, MaxCost)) {
Cascade = NextCascade;
EvictionCost Cost;
- for (const unsigned *AliasI = TRI->getOverlaps(PhysReg); *AliasI; ++AliasI) {
+ for (const uint16_t *AliasI = TRI->getOverlaps(PhysReg); *AliasI; ++AliasI) {
LiveIntervalUnion::Query &Q = query(VirtReg, *AliasI);
// If there is 10 or more interferences, chances are one is heavier.
if (Q.collectInterferingVRegs(10) >= 10)
// Once a live range becomes small enough, it is urgent that we find a
// register for it. This is indicated by an infinite spill weight. These
// urgent live ranges get to evict almost anything.
- bool Urgent = !VirtReg.isSpillable() && Intf->isSpillable();
+ //
+ // Also allow urgent evictions of unspillable ranges from a strictly
+ // larger allocation order.
+ bool Urgent = !VirtReg.isSpillable() &&
+ (Intf->isSpillable() ||
+ RegClassInfo.getNumAllocatableRegs(MRI->getRegClass(VirtReg.reg)) <
+ RegClassInfo.getNumAllocatableRegs(MRI->getRegClass(Intf->reg)));
// Only evict older cascades or live ranges without a cascade.
unsigned IntfCascade = ExtraRegInfo[Intf->reg].Cascade;
if (Cascade <= IntfCascade) {
DEBUG(dbgs() << "evicting " << PrintReg(PhysReg, TRI)
<< " interference: Cascade " << Cascade << '\n');
- for (const unsigned *AliasI = TRI->getOverlaps(PhysReg); *AliasI; ++AliasI) {
+ for (const uint16_t *AliasI = TRI->getOverlaps(PhysReg); *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) {
Order.rewind();
while (unsigned PhysReg = Order.next()) {
+ if (clobberedByRegMask(PhysReg))
+ continue;
if (TRI->getCostPerUse(PhysReg) >= CostPerUseLimit)
continue;
// The first use of a callee-saved register in a function has cost 1.
Intf.moveToBlock(BC.Number);
BC.Entry = BI.LiveIn ? SpillPlacement::PrefReg : SpillPlacement::DontCare;
BC.Exit = BI.LiveOut ? SpillPlacement::PrefReg : SpillPlacement::DontCare;
+ BC.ChangesValue = BI.FirstDef;
if (!Intf.hasInterference())
continue;
if (BI.LiveIn) {
if (Intf.first() <= Indexes->getMBBStartIdx(BC.Number))
BC.Entry = SpillPlacement::MustSpill, ++Ins;
- else if (Intf.first() < BI.FirstUse)
+ else if (Intf.first() < BI.FirstInstr)
BC.Entry = SpillPlacement::PrefSpill, ++Ins;
- else if (Intf.first() < BI.LastUse)
+ else if (Intf.first() < BI.LastInstr)
++Ins;
}
if (BI.LiveOut) {
if (Intf.last() >= SA->getLastSplitPoint(BC.Number))
BC.Exit = SpillPlacement::MustSpill, ++Ins;
- else if (Intf.last() > BI.LastUse)
+ else if (Intf.last() > BI.LastInstr)
BC.Exit = SpillPlacement::PrefSpill, ++Ins;
- else if (Intf.last() > BI.FirstUse)
+ else if (Intf.last() > BI.FirstInstr)
++Ins;
}
if (Cand.PhysReg)
addThroughConstraints(Cand.Intf, NewBlocks);
else
- SpillPlacer->addPrefSpill(NewBlocks);
+ // Provide a strong negative bias on through blocks to prevent unwanted
+ // liveness on loop backedges.
+ SpillPlacer->addPrefSpill(NewBlocks, /* Strong= */ true);
AddedTo = ActiveBlocks.size();
// Perhaps iterating can enable more bundles?
/// SA around all use blocks instead of forming bundle regions.
float RAGreedy::calcSpillCost() {
float Cost = 0;
- const LiveInterval &LI = SA->getParent();
ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA->getUseBlocks();
for (unsigned i = 0; i != UseBlocks.size(); ++i) {
const SplitAnalysis::BlockInfo &BI = UseBlocks[i];
Cost += SpillPlacer->getBlockFrequency(Number);
// Unless the value is redefined in the block.
- if (BI.LiveIn && BI.LiveOut) {
- SlotIndex Start, Stop;
- tie(Start, Stop) = Indexes->getMBBRange(Number);
- LiveInterval::const_iterator I = LI.find(Start);
- assert(I != LI.end() && "Expected live-in value");
- // Is there a different live-out value? If so, we need an extra spill
- // instruction.
- if (I->end < Stop)
- Cost += SpillPlacer->getBlockFrequency(Number);
- }
+ if (BI.LiveIn && BI.LiveOut && BI.FirstDef)
+ Cost += SpillPlacer->getBlockFrequency(Number);
}
return Cost;
}
return GlobalCost;
}
-/// splitAroundRegion - Split VirtReg around the region determined by
-/// LiveBundles. Make an effort to avoid interference from PhysReg.
+/// splitAroundRegion - Split the current live range around the regions
+/// determined by BundleCand and GlobalCand.
///
-/// 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.
+/// Before calling this function, GlobalCand and BundleCand must be initialized
+/// so each bundle is assigned to a valid candidate, or NoCand for the
+/// stack-bound bundles. The shared SA/SE SplitAnalysis and SplitEditor
+/// objects must be initialized for the current live range, and intervals
+/// created for the used candidates.
///
-void RAGreedy::splitAroundRegion(LiveInterval &VirtReg,
- GlobalSplitCandidate &Cand,
- SmallVectorImpl<LiveInterval*> &NewVRegs) {
- const BitVector &LiveBundles = Cand.LiveBundles;
-
- DEBUG({
- dbgs() << "Splitting around region for " << PrintReg(Cand.PhysReg, TRI)
- << " with bundles";
- for (int i = LiveBundles.find_first(); i>=0; i = LiveBundles.find_next(i))
- dbgs() << " EB#" << i;
- dbgs() << ".\n";
- });
-
- InterferenceCache::Cursor &Intf = Cand.Intf;
- LiveRangeEdit LREdit(VirtReg, NewVRegs, this);
- SE->reset(LREdit);
-
- // Create the main cross-block interval.
- const unsigned MainIntv = SE->openIntv();
+/// @param LREdit The LiveRangeEdit object handling the current split.
+/// @param UsedCands List of used GlobalCand entries. Every BundleCand value
+/// must appear in this list.
+void RAGreedy::splitAroundRegion(LiveRangeEdit &LREdit,
+ ArrayRef<unsigned> UsedCands) {
+ // These are the intervals created for new global ranges. We may create more
+ // intervals for local ranges.
+ const unsigned NumGlobalIntvs = LREdit.size();
+ DEBUG(dbgs() << "splitAroundRegion with " << NumGlobalIntvs << " globals.\n");
+ assert(NumGlobalIntvs && "No global intervals configured");
+
+ // Isolate even single instructions when dealing with a proper sub-class.
+ // That guarantees register class inflation for the stack interval because it
+ // is all copies.
+ unsigned Reg = SA->getParent().reg;
+ bool SingleInstrs = RegClassInfo.isProperSubClass(MRI->getRegClass(Reg));
// First handle all the blocks with uses.
ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA->getUseBlocks();
for (unsigned i = 0; i != UseBlocks.size(); ++i) {
const SplitAnalysis::BlockInfo &BI = UseBlocks[i];
- bool RegIn = BI.LiveIn &&
- LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 0)];
- bool RegOut = BI.LiveOut &&
- LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 1)];
+ unsigned Number = BI.MBB->getNumber();
+ unsigned IntvIn = 0, IntvOut = 0;
+ SlotIndex IntfIn, IntfOut;
+ if (BI.LiveIn) {
+ unsigned CandIn = BundleCand[Bundles->getBundle(Number, 0)];
+ if (CandIn != NoCand) {
+ GlobalSplitCandidate &Cand = GlobalCand[CandIn];
+ IntvIn = Cand.IntvIdx;
+ Cand.Intf.moveToBlock(Number);
+ IntfIn = Cand.Intf.first();
+ }
+ }
+ if (BI.LiveOut) {
+ unsigned CandOut = BundleCand[Bundles->getBundle(Number, 1)];
+ if (CandOut != NoCand) {
+ GlobalSplitCandidate &Cand = GlobalCand[CandOut];
+ IntvOut = Cand.IntvIdx;
+ Cand.Intf.moveToBlock(Number);
+ IntfOut = Cand.Intf.last();
+ }
+ }
// Create separate intervals for isolated blocks with multiple uses.
- if (!RegIn && !RegOut) {
+ if (!IntvIn && !IntvOut) {
DEBUG(dbgs() << "BB#" << BI.MBB->getNumber() << " isolated.\n");
- if (!BI.isOneInstr()) {
+ if (SA->shouldSplitSingleBlock(BI, SingleInstrs))
SE->splitSingleBlock(BI);
- SE->selectIntv(MainIntv);
- }
continue;
}
- Intf.moveToBlock(BI.MBB->getNumber());
-
- if (RegIn && RegOut)
- SE->splitLiveThroughBlock(BI.MBB->getNumber(),
- MainIntv, Intf.first(),
- MainIntv, Intf.last());
- else if (RegIn)
- SE->splitRegInBlock(BI, MainIntv, Intf.first());
+ if (IntvIn && IntvOut)
+ SE->splitLiveThroughBlock(Number, IntvIn, IntfIn, IntvOut, IntfOut);
+ else if (IntvIn)
+ SE->splitRegInBlock(BI, IntvIn, IntfIn);
else
- SE->splitRegOutBlock(BI, MainIntv, Intf.last());
+ SE->splitRegOutBlock(BI, IntvOut, IntfOut);
}
- // Handle live-through blocks.
- for (unsigned i = 0, e = Cand.ActiveBlocks.size(); i != e; ++i) {
- unsigned Number = Cand.ActiveBlocks[i];
- bool RegIn = LiveBundles[Bundles->getBundle(Number, 0)];
- bool RegOut = LiveBundles[Bundles->getBundle(Number, 1)];
- if (!RegIn && !RegOut)
- continue;
- Intf.moveToBlock(Number);
- SE->splitLiveThroughBlock(Number, RegIn ? MainIntv : 0, Intf.first(),
- RegOut ? MainIntv : 0, Intf.last());
+ // Handle live-through blocks. The relevant live-through blocks are stored in
+ // the ActiveBlocks list with each candidate. We need to filter out
+ // duplicates.
+ BitVector Todo = SA->getThroughBlocks();
+ for (unsigned c = 0; c != UsedCands.size(); ++c) {
+ ArrayRef<unsigned> Blocks = GlobalCand[UsedCands[c]].ActiveBlocks;
+ for (unsigned i = 0, e = Blocks.size(); i != e; ++i) {
+ unsigned Number = Blocks[i];
+ if (!Todo.test(Number))
+ continue;
+ Todo.reset(Number);
+
+ unsigned IntvIn = 0, IntvOut = 0;
+ SlotIndex IntfIn, IntfOut;
+
+ unsigned CandIn = BundleCand[Bundles->getBundle(Number, 0)];
+ if (CandIn != NoCand) {
+ GlobalSplitCandidate &Cand = GlobalCand[CandIn];
+ IntvIn = Cand.IntvIdx;
+ Cand.Intf.moveToBlock(Number);
+ IntfIn = Cand.Intf.first();
+ }
+
+ unsigned CandOut = BundleCand[Bundles->getBundle(Number, 1)];
+ if (CandOut != NoCand) {
+ GlobalSplitCandidate &Cand = GlobalCand[CandOut];
+ IntvOut = Cand.IntvIdx;
+ Cand.Intf.moveToBlock(Number);
+ IntfOut = Cand.Intf.last();
+ }
+ if (!IntvIn && !IntvOut)
+ continue;
+ SE->splitLiveThroughBlock(Number, IntvIn, IntfIn, IntvOut, IntfOut);
+ }
}
++NumGlobalSplits;
SmallVector<unsigned, 8> IntvMap;
SE->finish(&IntvMap);
- DebugVars->splitRegister(VirtReg.reg, LREdit.regs());
+ DebugVars->splitRegister(Reg, LREdit.regs());
ExtraRegInfo.resize(MRI->getNumVirtRegs());
unsigned OrigBlocks = SA->getNumLiveBlocks();
continue;
}
- // Main interval. Allow repeated splitting as long as the number of live
- // blocks is strictly decreasing. Otherwise force per-block splitting.
- if (IntvMap[i] == MainIntv) {
+ // Global intervals. Allow repeated splitting as long as the number of live
+ // blocks is strictly decreasing.
+ if (IntvMap[i] < NumGlobalIntvs) {
if (SA->countLiveBlocks(&Reg) >= OrigBlocks) {
DEBUG(dbgs() << "Main interval covers the same " << OrigBlocks
<< " blocks as original.\n");
unsigned RAGreedy::tryRegionSplit(LiveInterval &VirtReg, AllocationOrder &Order,
SmallVectorImpl<LiveInterval*> &NewVRegs) {
- float BestCost = Hysteresis * calcSpillCost();
- DEBUG(dbgs() << "Cost of isolating all blocks = " << BestCost << '\n');
- const unsigned NoCand = ~0u;
- unsigned BestCand = NoCand;
unsigned NumCands = 0;
+ unsigned BestCand = NoCand;
+ float BestCost;
+ SmallVector<unsigned, 8> UsedCands;
+
+ // Check if we can split this live range around a compact region.
+ bool HasCompact = calcCompactRegion(GlobalCand.front());
+ if (HasCompact) {
+ // Yes, keep GlobalCand[0] as the compact region candidate.
+ NumCands = 1;
+ BestCost = HUGE_VALF;
+ } else {
+ // No benefit from the compact region, our fallback will be per-block
+ // splitting. Make sure we find a solution that is cheaper than spilling.
+ BestCost = Hysteresis * calcSpillCost();
+ DEBUG(dbgs() << "Cost of isolating all blocks = " << BestCost << '\n');
+ }
Order.rewind();
while (unsigned PhysReg = Order.next()) {
unsigned WorstCount = ~0u;
unsigned Worst = 0;
for (unsigned i = 0; i != NumCands; ++i) {
- if (i == BestCand)
+ if (i == BestCand || !GlobalCand[i].PhysReg)
continue;
unsigned Count = GlobalCand[i].LiveBundles.count();
if (Count < WorstCount)
}
--NumCands;
GlobalCand[Worst] = GlobalCand[NumCands];
+ if (BestCand == NumCands)
+ BestCand = Worst;
}
if (GlobalCand.size() <= NumCands)
++NumCands;
}
- if (BestCand == NoCand)
+ // No solutions found, fall back to single block splitting.
+ if (!HasCompact && BestCand == NoCand)
+ return 0;
+
+ // Prepare split editor.
+ LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this);
+ SE->reset(LREdit, SplitSpillMode);
+
+ // Assign all edge bundles to the preferred candidate, or NoCand.
+ BundleCand.assign(Bundles->getNumBundles(), NoCand);
+
+ // Assign bundles for the best candidate region.
+ if (BestCand != NoCand) {
+ GlobalSplitCandidate &Cand = GlobalCand[BestCand];
+ if (unsigned B = Cand.getBundles(BundleCand, BestCand)) {
+ UsedCands.push_back(BestCand);
+ Cand.IntvIdx = SE->openIntv();
+ DEBUG(dbgs() << "Split for " << PrintReg(Cand.PhysReg, TRI) << " in "
+ << B << " bundles, intv " << Cand.IntvIdx << ".\n");
+ (void)B;
+ }
+ }
+
+ // Assign bundles for the compact region.
+ if (HasCompact) {
+ GlobalSplitCandidate &Cand = GlobalCand.front();
+ assert(!Cand.PhysReg && "Compact region has no physreg");
+ if (unsigned B = Cand.getBundles(BundleCand, 0)) {
+ UsedCands.push_back(0);
+ Cand.IntvIdx = SE->openIntv();
+ DEBUG(dbgs() << "Split for compact region in " << B << " bundles, intv "
+ << Cand.IntvIdx << ".\n");
+ (void)B;
+ }
+ }
+
+ splitAroundRegion(LREdit, UsedCands);
+ return 0;
+}
+
+
+//===----------------------------------------------------------------------===//
+// Per-Block Splitting
+//===----------------------------------------------------------------------===//
+
+/// tryBlockSplit - Split a global live range around every block with uses. This
+/// creates a lot of local live ranges, that will be split by tryLocalSplit if
+/// they don't allocate.
+unsigned RAGreedy::tryBlockSplit(LiveInterval &VirtReg, AllocationOrder &Order,
+ SmallVectorImpl<LiveInterval*> &NewVRegs) {
+ assert(&SA->getParent() == &VirtReg && "Live range wasn't analyzed");
+ unsigned Reg = VirtReg.reg;
+ bool SingleInstrs = RegClassInfo.isProperSubClass(MRI->getRegClass(Reg));
+ LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this);
+ SE->reset(LREdit, SplitSpillMode);
+ ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA->getUseBlocks();
+ for (unsigned i = 0; i != UseBlocks.size(); ++i) {
+ const SplitAnalysis::BlockInfo &BI = UseBlocks[i];
+ if (SA->shouldSplitSingleBlock(BI, SingleInstrs))
+ SE->splitSingleBlock(BI);
+ }
+ // No blocks were split.
+ if (LREdit.empty())
+ return 0;
+
+ // We did split for some blocks.
+ SmallVector<unsigned, 8> IntvMap;
+ SE->finish(&IntvMap);
+
+ // Tell LiveDebugVariables about the new ranges.
+ DebugVars->splitRegister(Reg, LREdit.regs());
+
+ ExtraRegInfo.resize(MRI->getNumVirtRegs());
+
+ // Sort out the new intervals created by splitting. The remainder interval
+ // goes straight to spilling, the new local ranges get to stay RS_New.
+ for (unsigned i = 0, e = LREdit.size(); i != e; ++i) {
+ LiveInterval &LI = *LREdit.get(i);
+ if (getStage(LI) == RS_New && IntvMap[i] == 0)
+ setStage(LI, RS_Spill);
+ }
+
+ if (VerifyEnabled)
+ MF->verify(this, "After splitting live range around basic blocks");
+ return 0;
+}
+
+
+//===----------------------------------------------------------------------===//
+// Per-Instruction Splitting
+//===----------------------------------------------------------------------===//
+
+/// tryInstructionSplit - Split a live range around individual instructions.
+/// This is normally not worthwhile since the spiller is doing essentially the
+/// same thing. However, when the live range is in a constrained register
+/// class, it may help to insert copies such that parts of the live range can
+/// be moved to a larger register class.
+///
+/// This is similar to spilling to a larger register class.
+unsigned
+RAGreedy::tryInstructionSplit(LiveInterval &VirtReg, AllocationOrder &Order,
+ SmallVectorImpl<LiveInterval*> &NewVRegs) {
+ // There is no point to this if there are no larger sub-classes.
+ if (!RegClassInfo.isProperSubClass(MRI->getRegClass(VirtReg.reg)))
+ return 0;
+
+ // Always enable split spill mode, since we're effectively spilling to a
+ // register.
+ LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this);
+ SE->reset(LREdit, SplitEditor::SM_Size);
+
+ ArrayRef<SlotIndex> Uses = SA->getUseSlots();
+ if (Uses.size() <= 1)
+ return 0;
+
+ DEBUG(dbgs() << "Split around " << Uses.size() << " individual instrs.\n");
+
+ // Split around every non-copy instruction.
+ for (unsigned i = 0; i != Uses.size(); ++i) {
+ if (const MachineInstr *MI = Indexes->getInstructionFromIndex(Uses[i]))
+ if (MI->isFullCopy()) {
+ DEBUG(dbgs() << " skip:\t" << Uses[i] << '\t' << *MI);
+ continue;
+ }
+ SE->openIntv();
+ SlotIndex SegStart = SE->enterIntvBefore(Uses[i]);
+ SlotIndex SegStop = SE->leaveIntvAfter(Uses[i]);
+ SE->useIntv(SegStart, SegStop);
+ }
+
+ if (LREdit.empty()) {
+ DEBUG(dbgs() << "All uses were copies.\n");
return 0;
+ }
- splitAroundRegion(VirtReg, GlobalCand[BestCand], NewVRegs);
+ SmallVector<unsigned, 8> IntvMap;
+ SE->finish(&IntvMap);
+ DebugVars->splitRegister(VirtReg.reg, LREdit.regs());
+ ExtraRegInfo.resize(MRI->getNumVirtRegs());
+
+ // Assign all new registers to RS_Spill. This was the last chance.
+ setStage(LREdit.begin(), LREdit.end(), RS_Spill);
return 0;
}
SmallVectorImpl<float> &GapWeight) {
assert(SA->getUseBlocks().size() == 1 && "Not a local interval");
const SplitAnalysis::BlockInfo &BI = SA->getUseBlocks().front();
- const SmallVectorImpl<SlotIndex> &Uses = SA->UseSlots;
+ ArrayRef<SlotIndex> Uses = SA->getUseSlots();
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;
+ SlotIndex StartIdx =
+ BI.LiveIn ? BI.FirstInstr.getBaseIndex() : BI.FirstInstr;
+ SlotIndex StopIdx =
+ BI.LiveOut ? BI.LastInstr.getBoundaryIndex() : BI.LastInstr;
GapWeight.assign(NumGaps, 0.0f);
// Add interference from each overlapping register.
- for (const unsigned *AI = TRI->getOverlaps(PhysReg); *AI; ++AI) {
+ for (const uint16_t *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.
+ // We know that VirtReg is a continuous interval from FirstInstr to
+ // LastInstr, 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);
+ LiveIntervalUnion::SegmentIter IntI = getLiveUnion(*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())
// 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.
+ // that the interval is continuous from FirstInstr to LastInstr. We should
+ // make sure that we don't do anything illegal to such an interval, though.
- const SmallVectorImpl<SlotIndex> &Uses = SA->UseSlots;
+ ArrayRef<SlotIndex> Uses = SA->getUseSlots();
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() << ' ' << Uses[i];
dbgs() << '\n';
});
+ // If VirtReg is live across any register mask operands, compute a list of
+ // gaps with register masks.
+ SmallVector<unsigned, 8> RegMaskGaps;
+ if (!UsableRegs.empty()) {
+ // Get regmask slots for the whole block.
+ ArrayRef<SlotIndex> RMS = LIS->getRegMaskSlotsInBlock(BI.MBB->getNumber());
+ DEBUG(dbgs() << RMS.size() << " regmasks in block:");
+ // Constrain to VirtReg's live range.
+ unsigned ri = std::lower_bound(RMS.begin(), RMS.end(),
+ Uses.front().getRegSlot()) - RMS.begin();
+ unsigned re = RMS.size();
+ for (unsigned i = 0; i != NumGaps && ri != re; ++i) {
+ // Look for Uses[i] <= RMS <= Uses[i+1].
+ assert(!SlotIndex::isEarlierInstr(RMS[ri], Uses[i]));
+ if (SlotIndex::isEarlierInstr(Uses[i+1], RMS[ri]))
+ continue;
+ // Skip a regmask on the same instruction as the last use. It doesn't
+ // overlap the live range.
+ if (SlotIndex::isSameInstr(Uses[i+1], RMS[ri]) && i+1 == NumGaps)
+ break;
+ DEBUG(dbgs() << ' ' << RMS[ri] << ':' << Uses[i] << '-' << Uses[i+1]);
+ RegMaskGaps.push_back(i);
+ // Advance ri to the next gap. A regmask on one of the uses counts in
+ // both gaps.
+ while (ri != re && SlotIndex::isEarlierInstr(RMS[ri], Uses[i+1]))
+ ++ri;
+ }
+ DEBUG(dbgs() << '\n');
+ }
+
// Since we allow local split results to be split again, there is a risk of
// creating infinite loops. It is tempting to require that the new live
// ranges have less instructions than the original. That would guarantee
// order to make use of PhysReg between UseSlots[i] and UseSlots[i+1].
calcGapWeights(PhysReg, GapWeight);
+ // Remove any gaps with regmask clobbers.
+ if (clobberedByRegMask(PhysReg))
+ for (unsigned i = 0, e = RegMaskGaps.size(); i != e; ++i)
+ GapWeight[RegMaskGaps[i]] = HUGE_VALF;
+
// Try to find the best sequence of gaps to close.
// The new spill weight must be larger than any gap interference.
<< '-' << Uses[BestAfter] << ", " << BestDiff
<< ", " << (BestAfter - BestBefore + 1) << " instrs\n");
- LiveRangeEdit LREdit(VirtReg, NewVRegs, this);
+ LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this);
SE->reset(LREdit);
SE->openIntv();
/// @return Physreg when VirtReg may be assigned and/or new NewVRegs.
unsigned RAGreedy::trySplit(LiveInterval &VirtReg, AllocationOrder &Order,
SmallVectorImpl<LiveInterval*>&NewVRegs) {
+ // Ranges must be Split2 or less.
+ if (getStage(VirtReg) >= RS_Spill)
+ return 0;
+
// Local intervals are handled separately.
if (LIS->intervalIsInOneMBB(VirtReg)) {
NamedRegionTimer T("Local Splitting", TimerGroupName, TimePassesIsEnabled);
SA->analyze(&VirtReg);
- return tryLocalSplit(VirtReg, Order, NewVRegs);
+ unsigned PhysReg = tryLocalSplit(VirtReg, Order, NewVRegs);
+ if (PhysReg || !NewVRegs.empty())
+ return PhysReg;
+ return tryInstructionSplit(VirtReg, Order, NewVRegs);
}
NamedRegionTimer T("Global Splitting", TimerGroupName, TimePassesIsEnabled);
- // Ranges must be Split2 or less.
- if (getStage(VirtReg) >= RS_Spill)
- return 0;
-
SA->analyze(&VirtReg);
// FIXME: SplitAnalysis may repair broken live ranges coming from the
return PhysReg;
}
- // Then isolate blocks with multiple uses.
- SplitAnalysis::BlockPtrSet Blocks;
- if (SA->getMultiUseBlocks(Blocks)) {
- LiveRangeEdit LREdit(VirtReg, NewVRegs, this);
- SE->reset(LREdit);
- SE->splitSingleBlocks(Blocks);
- setStage(NewVRegs.begin(), NewVRegs.end(), RS_Spill);
- if (VerifyEnabled)
- MF->verify(this, "After splitting live range around basic blocks");
- }
-
- // Don't assign any physregs.
- return 0;
+ // Then isolate blocks.
+ return tryBlockSplit(VirtReg, Order, NewVRegs);
}
unsigned RAGreedy::selectOrSplit(LiveInterval &VirtReg,
SmallVectorImpl<LiveInterval*> &NewVRegs) {
+ // Check if VirtReg is live across any calls.
+ UsableRegs.clear();
+ if (LIS->checkRegMaskInterference(VirtReg, UsableRegs))
+ DEBUG(dbgs() << "Live across regmasks.\n");
+
// First try assigning a free register.
AllocationOrder Order(VirtReg.reg, *VRM, RegClassInfo);
if (unsigned PhysReg = tryAssign(VirtReg, Order, NewVRegs))
// Finally spill VirtReg itself.
NamedRegionTimer T("Spiller", TimerGroupName, TimePassesIsEnabled);
- LiveRangeEdit LRE(VirtReg, NewVRegs, this);
+ LiveRangeEdit LRE(&VirtReg, NewVRegs, *MF, *LIS, VRM, this);
spiller().spill(LRE);
setStage(NewVRegs.begin(), NewVRegs.end(), RS_Done);
ExtraRegInfo.clear();
ExtraRegInfo.resize(MRI->getNumVirtRegs());
NextCascade = 1;
- IntfCache.init(MF, &PhysReg2LiveUnion[0], Indexes, TRI);
+ IntfCache.init(MF, &getLiveUnion(0), Indexes, LIS, TRI);
+ GlobalCand.resize(32); // This will grow as needed.
allocatePhysRegs();
addMBBLiveIns(MF);
}
// Write out new DBG_VALUE instructions.
- DebugVars->emitDebugValues(VRM);
+ {
+ NamedRegionTimer T("Emit Debug Info", TimerGroupName, TimePassesIsEnabled);
+ DebugVars->emitDebugValues(VRM);
+ }
- // The pass output is in VirtRegMap. Release all the transient data.
+ // All machine operands and other references to virtual registers have been
+ // replaced. Remove the virtual registers and release all the transient data.
+ VRM->clearAllVirt();
+ MRI->clearVirtRegs();
releaseMemory();
return true;
projects / oota-llvm.git / blobdiff