#include "LiveRangeEdit.h"
#include "RegAllocBase.h"
#include "Spiller.h"
+#include "SpillPlacement.h"
#include "SplitKit.h"
#include "VirtRegMap.h"
#include "VirtRegRewriter.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"
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;
+ // splitting state.
+
+ /// All basic blocks where the current register is live.
+ SmallVector<SpillPlacement::BlockConstraint, 8> SpillConstraints;
+
+ /// Additional information about basic blocks where the current variable is
+ /// live. Such a block will look like one of these templates:
+ ///
+ /// 1. | o---x | Internal to block. Variable is only live in this block.
+ /// 2. |---x | Live-in, kill.
+ /// 3. | o---| Def, live-out.
+ /// 4. |---x o---| Live-in, kill, def, live-out.
+ /// 5. |---o---o---| Live-through with uses or defs.
+ /// 6. |-----------| Live-through without uses. Transparent.
+ ///
+ struct BlockInfo {
+ const MachineBasicBlock *MBB;
+ SlotIndex FirstUse; ///< First instr using current reg.
+ SlotIndex LastUse; ///< Last instr using current reg.
+ SlotIndex Kill; ///< Interval end point inside block.
+ SlotIndex Def; ///< Interval start point inside block.
+ bool Uses; ///< Current reg has uses or defs in block.
+ bool LiveThrough; ///< Live in whole block (Templ 5. or 6. above).
+ bool LiveIn; ///< Current reg is live in.
+ bool LiveOut; ///< Current reg is live out.
+
+ // Per-interference pattern scratch data.
+ bool OverlapEntry; ///< Interference overlaps entering interval.
+ bool OverlapExit; ///< Interference overlaps exiting interval.
+ };
+
+ /// Basic blocks where var is live. This array is parallel to
+ /// SpillConstraints.
+ SmallVector<BlockInfo, 8> LiveBlocks;
+
public:
RAGreedy();
unsigned findInterferenceFreeReg(MachineLoopRange*,
LiveInterval&, AllocationOrder&);
float calcInterferenceWeight(LiveInterval&, unsigned);
+ void calcLiveBlockInfo(LiveInterval&);
+ float calcInterferenceInfo(LiveInterval&, unsigned);
+ float calcGlobalSplitCost(const BitVector&);
unsigned tryReassign(LiveInterval&, AllocationOrder&);
+ unsigned tryRegionSplit(LiveInterval&, AllocationOrder&,
+ SmallVectorImpl<LiveInterval*>&);
unsigned trySplit(LiveInterval&, AllocationOrder&,
SmallVectorImpl<LiveInterval*>&);
unsigned trySpillInterferences(LiveInterval&, AllocationOrder&,
}
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);
}
/// @return Physreg when VirtReg may be assigned and/or new SplitVRegs.
unsigned RAGreedy::trySplit(LiveInterval &VirtReg, AllocationOrder &Order,
SmallVectorImpl<LiveInterval*>&SplitVRegs) {
+ // Don't attempt splitting on local intervals for now.
+ if (LIS->intervalIsInOneMBB(VirtReg))
+ return 0;
+
NamedRegionTimer T("Splitter", TimerGroupName, TimePassesIsEnabled);
SA->analyze(&VirtReg);
}
+//===----------------------------------------------------------------------===//
+// Region Splitting
+//===----------------------------------------------------------------------===//
+
+/// calcLiveBlockInfo - Fill the LiveBlocks array with information about blocks
+/// where VirtReg is live.
+/// The SpillConstraints array is minimally initialized with MBB->getNumber().
+void RAGreedy::calcLiveBlockInfo(LiveInterval &VirtReg) {
+ LiveBlocks.clear();
+ SpillConstraints.clear();
+
+ assert(!VirtReg.empty() && "Cannot allocate an empty interval");
+ LiveInterval::const_iterator LVI = VirtReg.begin();
+ LiveInterval::const_iterator LVE = VirtReg.end();
+
+ SmallVectorImpl<SlotIndex>::const_iterator UseI, UseE;
+ UseI = SA->UseSlots.begin();
+ UseE = SA->UseSlots.end();
+
+ // Loop over basic blocks where VirtReg is live.
+ MachineFunction::const_iterator MFI = Indexes->getMBBFromIndex(LVI->start);
+ for (;;) {
+ // Block constraints depend on the interference pattern.
+ // Just allocate them here, don't compute anything.
+ SpillPlacement::BlockConstraint BC;
+ BC.Number = MFI->getNumber();
+ SpillConstraints.push_back(BC);
+
+ BlockInfo BI;
+ BI.MBB = MFI;
+ SlotIndex Start, Stop;
+ tie(Start, Stop) = Indexes->getMBBRange(BI.MBB);
+
+ // LVI is the first live segment overlapping MBB.
+ BI.LiveIn = LVI->start <= Start;
+ if (!BI.LiveIn)
+ BI.Def = LVI->start;
+
+ // Find the first and last uses in the block.
+ BI.Uses = SA->hasUses(MFI);
+ if (BI.Uses && UseI != UseE) {
+ BI.FirstUse = *UseI;
+ assert(BI.FirstUse >= Start);
+ do ++UseI;
+ while (UseI != UseE && *UseI < Stop);
+ BI.LastUse = UseI[-1];
+ assert(BI.LastUse < Stop);
+ }
+
+ // Look for gaps in the live range.
+ bool hasGap = false;
+ BI.LiveOut = true;
+ while (LVI->end < Stop) {
+ SlotIndex LastStop = LVI->end;
+ if (++LVI == LVE || LVI->start >= Stop) {
+ BI.Kill = LastStop;
+ BI.LiveOut = false;
+ break;
+ }
+ if (LastStop < LVI->start) {
+ hasGap = true;
+ BI.Kill = LastStop;
+ BI.Def = LVI->start;
+ }
+ }
+
+ // Don't set LiveThrough when the block has a gap.
+ BI.LiveThrough = !hasGap && BI.LiveIn && BI.LiveOut;
+ LiveBlocks.push_back(BI);
+
+ // LVI is now at LVE or LVI->end >= Stop.
+ if (LVI == LVE)
+ break;
+
+ // Live segment ends exactly at Stop. Move to the next segment.
+ if (LVI->end == Stop && ++LVI == LVE)
+ break;
+
+ // Pick the next basic block.
+ if (LVI->start < Stop)
+ ++MFI;
+ else
+ MFI = Indexes->getMBBFromIndex(LVI->start);
+ }
+}
+
+/// 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.
+ for (unsigned i = 0, e = LiveBlocks.size(); i != e; ++i) {
+ BlockInfo &BI = LiveBlocks[i];
+ SpillPlacement::BlockConstraint &BC = SpillConstraints[i];
+ 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;
+ DEBUG(PhysReg2LiveUnion[*AI].print(dbgs(), TRI));
+ LiveIntervalUnion::SegmentIter IntI =
+ PhysReg2LiveUnion[*AI].find(VirtReg.beginIndex());
+ if (!IntI.valid())
+ continue;
+
+ for (unsigned i = 0, e = LiveBlocks.size(); i != e; ++i) {
+ BlockInfo &BI = 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) {
+ // Check if interference is live-in - force spill.
+ if (BC.Entry != SpillPlacement::MustSpill) {
+ BC.Entry = SpillPlacement::PrefSpill;
+ IntI.advanceTo(Start);
+ if (IntI.valid() && IntI.start() <= Start)
+ BC.Entry = SpillPlacement::MustSpill;
+ }
+
+ // Check if interference is live-out - force spill.
+ if (BC.Exit != SpillPlacement::MustSpill) {
+ BC.Exit = SpillPlacement::PrefSpill;
+ IntI.advanceTo(Stop);
+ if (IntI.valid() && IntI.start() < Stop)
+ BC.Exit = SpillPlacement::MustSpill;
+ }
+
+ // Nothing more to do for this transparent block.
+ if (!IntI.valid())
+ break;
+ 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;
+
+ // Interference is live-in - force spill.
+ if (IntI.start() <= Start)
+ BC.Entry = SpillPlacement::MustSpill;
+ // Not live in, but before the first use.
+ else if (IntI.start() < BI.FirstUse)
+ BC.Entry = SpillPlacement::PrefSpill;
+ }
+
+ // 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;
+ }
+ // Is the interference live-out?
+ IntI.advanceTo(Stop);
+ if (!IntI.valid())
+ break;
+ if (IntI.start() < Stop)
+ BC.Exit = SpillPlacement::MustSpill;
+ }
+ }
+ }
+
+ // Accumulate a local cost of this interference pattern.
+ float LocalCost = 0;
+ for (unsigned i = 0, e = LiveBlocks.size(); i != e; ++i) {
+ BlockInfo &BI = 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 = LiveBlocks.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(LiveBlocks[i].MBB);
+ }
+ DEBUG(dbgs() << "Global cost = " << GlobalCost << '\n');
+ return GlobalCost;
+}
+
+unsigned RAGreedy::tryRegionSplit(LiveInterval &VirtReg, AllocationOrder &Order,
+ SmallVectorImpl<LiveInterval*> &NewVRegs) {
+ calcLiveBlockInfo(VirtReg);
+ 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;
+ if (!SpillPlacer->placeSpills(SpillConstraints, LiveBundles))
+ Cost += calcGlobalSplitCost(LiveBundles);
+ if (!BestReg || Cost < BestCost) {
+ BestReg = PhysReg;
+ BestCost = Cost;
+ BestBundles.swap(LiveBundles);
+ }
+ }
+ // FIXME: Actually execute the split.
+ return 0;
+}
+
//===----------------------------------------------------------------------===//
// Spilling
//===----------------------------------------------------------------------===//
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>();
+ Bundles = &getAnalysis<EdgeBundles>();
+ SpillPlacer = &getAnalysis<SpillPlacement>();
+
SA.reset(new SplitAnalysis(*MF, *LIS, *Loops));
allocatePhysRegs();
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