#include "SplitKit.h"
#include "LiveRangeEdit.h"
#include "VirtRegMap.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
-#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
AllowSplit("spiller-splits-edges",
cl::desc("Allow critical edge splitting during spilling"));
+STATISTIC(NumFinished, "Number of splits finished");
+STATISTIC(NumSimple, "Number of splits that were simple");
+
//===----------------------------------------------------------------------===//
// Split Analysis
//===----------------------------------------------------------------------===//
-SplitAnalysis::SplitAnalysis(const MachineFunction &mf,
+SplitAnalysis::SplitAnalysis(const VirtRegMap &vrm,
const LiveIntervals &lis,
const MachineLoopInfo &mli)
- : MF(mf),
+ : MF(vrm.getMachineFunction()),
+ VRM(vrm),
LIS(lis),
Loops(mli),
- TII(*mf.getTarget().getInstrInfo()),
+ TII(*MF.getTarget().getInstrInfo()),
CurLI(0) {}
void SplitAnalysis::clear() {
UseSlots.clear();
UsingInstrs.clear();
UsingBlocks.clear();
- UsingLoops.clear();
+ LiveBlocks.clear();
CurLI = 0;
}
continue;
UseSlots.push_back(LIS.getInstructionIndex(MI).getDefIndex());
MachineBasicBlock *MBB = MI->getParent();
- if (UsingBlocks[MBB]++)
- continue;
- for (MachineLoop *Loop = Loops.getLoopFor(MBB); Loop;
- Loop = Loop->getParentLoop())
- UsingLoops[Loop]++;
+ UsingBlocks[MBB]++;
}
array_pod_sort(UseSlots.begin(), UseSlots.end());
- DEBUG(dbgs() << " counted "
- << UsingInstrs.size() << " instrs, "
- << UsingBlocks.size() << " blocks, "
- << UsingLoops.size() << " loops.\n");
-}
-
-void SplitAnalysis::print(const BlockPtrSet &B, raw_ostream &OS) const {
- for (BlockPtrSet::const_iterator I = B.begin(), E = B.end(); I != E; ++I) {
- unsigned count = UsingBlocks.lookup(*I);
- OS << " BB#" << (*I)->getNumber();
- if (count)
- OS << '(' << count << ')';
- }
-}
-// Get three sets of basic blocks surrounding a loop: Blocks inside the loop,
-// predecessor blocks, and exit blocks.
-void SplitAnalysis::getLoopBlocks(const MachineLoop *Loop, LoopBlocks &Blocks) {
- Blocks.clear();
-
- // Blocks in the loop.
- Blocks.Loop.insert(Loop->block_begin(), Loop->block_end());
-
- // Predecessor blocks.
- const MachineBasicBlock *Header = Loop->getHeader();
- for (MachineBasicBlock::const_pred_iterator I = Header->pred_begin(),
- E = Header->pred_end(); I != E; ++I)
- if (!Blocks.Loop.count(*I))
- Blocks.Preds.insert(*I);
-
- // Exit blocks.
- for (MachineLoop::block_iterator I = Loop->block_begin(),
- E = Loop->block_end(); I != E; ++I) {
- const MachineBasicBlock *MBB = *I;
- for (MachineBasicBlock::const_succ_iterator SI = MBB->succ_begin(),
- SE = MBB->succ_end(); SI != SE; ++SI)
- if (!Blocks.Loop.count(*SI))
- Blocks.Exits.insert(*SI);
+ // Compute per-live block info.
+ if (!calcLiveBlockInfo()) {
+ // FIXME: calcLiveBlockInfo found inconsistencies in the live range.
+ // I am looking at you, SimpleRegisterCoalescing!
+ DEBUG(dbgs() << "*** Fixing inconsistent live interval! ***\n");
+ const_cast<LiveIntervals&>(LIS)
+ .shrinkToUses(const_cast<LiveInterval*>(CurLI));
+ LiveBlocks.clear();
+ bool fixed = calcLiveBlockInfo();
+ (void)fixed;
+ assert(fixed && "Couldn't fix broken live interval");
}
-}
-
-void SplitAnalysis::print(const LoopBlocks &B, raw_ostream &OS) const {
- OS << "Loop:";
- print(B.Loop, OS);
- OS << ", preds:";
- print(B.Preds, OS);
- OS << ", exits:";
- print(B.Exits, OS);
-}
-/// analyzeLoopPeripheralUse - Return an enum describing how CurLI is used in
-/// and around the Loop.
-SplitAnalysis::LoopPeripheralUse SplitAnalysis::
-analyzeLoopPeripheralUse(const SplitAnalysis::LoopBlocks &Blocks) {
- LoopPeripheralUse use = ContainedInLoop;
- for (BlockCountMap::iterator I = UsingBlocks.begin(), E = UsingBlocks.end();
- I != E; ++I) {
- const MachineBasicBlock *MBB = I->first;
- // Is this a peripheral block?
- if (use < MultiPeripheral &&
- (Blocks.Preds.count(MBB) || Blocks.Exits.count(MBB))) {
- if (I->second > 1) use = MultiPeripheral;
- else use = SinglePeripheral;
- continue;
+ DEBUG(dbgs() << "Analyze counted "
+ << UsingInstrs.size() << " instrs, "
+ << UsingBlocks.size() << " blocks, "
+ << LiveBlocks.size() << " spanned.\n");
+}
+
+/// calcLiveBlockInfo - Fill the LiveBlocks array with information about blocks
+/// where CurLI is live.
+bool SplitAnalysis::calcLiveBlockInfo() {
+ if (CurLI->empty())
+ return true;
+
+ LiveInterval::const_iterator LVI = CurLI->begin();
+ LiveInterval::const_iterator LVE = CurLI->end();
+
+ SmallVectorImpl<SlotIndex>::const_iterator UseI, UseE;
+ UseI = UseSlots.begin();
+ UseE = UseSlots.end();
+
+ // Loop over basic blocks where CurLI is live.
+ MachineFunction::iterator MFI = LIS.getMBBFromIndex(LVI->start);
+ for (;;) {
+ BlockInfo BI;
+ BI.MBB = MFI;
+ tie(BI.Start, BI.Stop) = LIS.getSlotIndexes()->getMBBRange(BI.MBB);
+
+ // The last split point is the latest possible insertion point that dominates
+ // all successor blocks. If interference reaches LastSplitPoint, it is not
+ // possible to insert a split or reload that makes CurLI live in the
+ // outgoing bundle.
+ MachineBasicBlock::iterator LSP = LIS.getLastSplitPoint(*CurLI, BI.MBB);
+ if (LSP == BI.MBB->end())
+ BI.LastSplitPoint = BI.Stop;
+ else
+ BI.LastSplitPoint = LIS.getInstructionIndex(LSP);
+
+ // LVI is the first live segment overlapping MBB.
+ BI.LiveIn = LVI->start <= BI.Start;
+ if (!BI.LiveIn)
+ BI.Def = LVI->start;
+
+ // Find the first and last uses in the block.
+ BI.Uses = hasUses(MFI);
+ if (BI.Uses && UseI != UseE) {
+ BI.FirstUse = *UseI;
+ assert(BI.FirstUse >= BI.Start);
+ do ++UseI;
+ while (UseI != UseE && *UseI < BI.Stop);
+ BI.LastUse = UseI[-1];
+ assert(BI.LastUse < BI.Stop);
}
- // Is it a loop block?
- if (Blocks.Loop.count(MBB))
- continue;
- // It must be an unrelated block.
- DEBUG(dbgs() << ", outside: BB#" << MBB->getNumber());
- return OutsideLoop;
- }
- return use;
-}
-/// getCriticalExits - It may be necessary to partially break critical edges
-/// leaving the loop if an exit block has predecessors from outside the loop
-/// periphery.
-void SplitAnalysis::getCriticalExits(const SplitAnalysis::LoopBlocks &Blocks,
- BlockPtrSet &CriticalExits) {
- CriticalExits.clear();
-
- // A critical exit block has CurLI live-in, and has a predecessor that is not
- // in the loop nor a loop predecessor. For such an exit block, the edges
- // carrying the new variable must be moved to a new pre-exit block.
- for (BlockPtrSet::iterator I = Blocks.Exits.begin(), E = Blocks.Exits.end();
- I != E; ++I) {
- const MachineBasicBlock *Exit = *I;
- // A single-predecessor exit block is definitely not a critical edge.
- if (Exit->pred_size() == 1)
- continue;
- // This exit may not have CurLI live in at all. No need to split.
- if (!LIS.isLiveInToMBB(*CurLI, Exit))
- continue;
- // Does this exit block have a predecessor that is not a loop block or loop
- // predecessor?
- for (MachineBasicBlock::const_pred_iterator PI = Exit->pred_begin(),
- PE = Exit->pred_end(); PI != PE; ++PI) {
- const MachineBasicBlock *Pred = *PI;
- if (Blocks.Loop.count(Pred) || Blocks.Preds.count(Pred))
- continue;
- // This is a critical exit block, and we need to split the exit edge.
- CriticalExits.insert(Exit);
- break;
+ // Look for gaps in the live range.
+ bool hasGap = false;
+ BI.LiveOut = true;
+ while (LVI->end < BI.Stop) {
+ SlotIndex LastStop = LVI->end;
+ if (++LVI == LVE || LVI->start >= BI.Stop) {
+ BI.Kill = LastStop;
+ BI.LiveOut = false;
+ break;
+ }
+ if (LastStop < LVI->start) {
+ hasGap = true;
+ BI.Kill = LastStop;
+ BI.Def = LVI->start;
+ }
}
- }
-}
-void SplitAnalysis::getCriticalPreds(const SplitAnalysis::LoopBlocks &Blocks,
- BlockPtrSet &CriticalPreds) {
- CriticalPreds.clear();
-
- // A critical predecessor block has CurLI live-out, and has a successor that
- // has CurLI live-in and is not in the loop nor a loop exit block. For such a
- // predecessor block, we must carry the value in both the 'inside' and
- // 'outside' registers.
- for (BlockPtrSet::iterator I = Blocks.Preds.begin(), E = Blocks.Preds.end();
- I != E; ++I) {
- const MachineBasicBlock *Pred = *I;
- // Definitely not a critical edge.
- if (Pred->succ_size() == 1)
- continue;
- // This block may not have CurLI live out at all if there is a PHI.
- if (!LIS.isLiveOutOfMBB(*CurLI, Pred))
- continue;
- // Does this block have a successor outside the loop?
- for (MachineBasicBlock::const_pred_iterator SI = Pred->succ_begin(),
- SE = Pred->succ_end(); SI != SE; ++SI) {
- const MachineBasicBlock *Succ = *SI;
- if (Blocks.Loop.count(Succ) || Blocks.Exits.count(Succ))
- continue;
- if (!LIS.isLiveInToMBB(*CurLI, Succ))
- continue;
- // This is a critical predecessor block.
- CriticalPreds.insert(Pred);
+ // Don't set LiveThrough when the block has a gap.
+ BI.LiveThrough = !hasGap && BI.LiveIn && BI.LiveOut;
+ LiveBlocks.push_back(BI);
+
+ // FIXME: This should never happen. The live range stops or starts without a
+ // corresponding use. An earlier pass did something wrong.
+ if (!BI.LiveThrough && !BI.Uses)
+ return false;
+
+ // LVI is now at LVE or LVI->end >= Stop.
+ if (LVI == LVE)
break;
- }
- }
-}
-/// canSplitCriticalExits - Return true if it is possible to insert new exit
-/// blocks before the blocks in CriticalExits.
-bool
-SplitAnalysis::canSplitCriticalExits(const SplitAnalysis::LoopBlocks &Blocks,
- BlockPtrSet &CriticalExits) {
- // If we don't allow critical edge splitting, require no critical exits.
- if (!AllowSplit)
- return CriticalExits.empty();
-
- for (BlockPtrSet::iterator I = CriticalExits.begin(), E = CriticalExits.end();
- I != E; ++I) {
- const MachineBasicBlock *Succ = *I;
- // We want to insert a new pre-exit MBB before Succ, and change all the
- // in-loop blocks to branch to the pre-exit instead of Succ.
- // Check that all the in-loop predecessors can be changed.
- for (MachineBasicBlock::const_pred_iterator PI = Succ->pred_begin(),
- PE = Succ->pred_end(); PI != PE; ++PI) {
- const MachineBasicBlock *Pred = *PI;
- // The external predecessors won't be altered.
- if (!Blocks.Loop.count(Pred) && !Blocks.Preds.count(Pred))
- continue;
- if (!canAnalyzeBranch(Pred))
- return false;
- }
+ // Live segment ends exactly at Stop. Move to the next segment.
+ if (LVI->end == BI.Stop && ++LVI == LVE)
+ break;
- // If Succ's layout predecessor falls through, that too must be analyzable.
- // We need to insert the pre-exit block in the gap.
- MachineFunction::const_iterator MFI = Succ;
- if (MFI == MF.begin())
- continue;
- if (!canAnalyzeBranch(--MFI))
- return false;
+ // Pick the next basic block.
+ if (LVI->start < BI.Stop)
+ ++MFI;
+ else
+ MFI = LIS.getMBBFromIndex(LVI->start);
}
- // No problems found.
return true;
}
-void SplitAnalysis::analyze(const LiveInterval *li) {
- clear();
- CurLI = li;
- analyzeUses();
-}
-
-void SplitAnalysis::getSplitLoops(LoopPtrSet &Loops) {
- assert(CurLI && "Call analyze() before getSplitLoops");
- if (UsingLoops.empty())
- return;
-
- LoopBlocks Blocks;
- BlockPtrSet CriticalExits;
+bool SplitAnalysis::isOriginalEndpoint(SlotIndex Idx) const {
+ unsigned OrigReg = VRM.getOriginal(CurLI->reg);
+ const LiveInterval &Orig = LIS.getInterval(OrigReg);
+ assert(!Orig.empty() && "Splitting empty interval?");
+ LiveInterval::const_iterator I = Orig.find(Idx);
- // We split around loops where CurLI is used outside the periphery.
- for (LoopCountMap::const_iterator I = UsingLoops.begin(),
- E = UsingLoops.end(); I != E; ++I) {
- const MachineLoop *Loop = I->first;
- getLoopBlocks(Loop, Blocks);
- DEBUG({ dbgs() << " "; print(Blocks, dbgs()); });
+ // Range containing Idx should begin at Idx.
+ if (I != Orig.end() && I->start <= Idx)
+ return I->start == Idx;
- switch(analyzeLoopPeripheralUse(Blocks)) {
- case OutsideLoop:
- break;
- case MultiPeripheral:
- // FIXME: We could split a live range with multiple uses in a peripheral
- // block and still make progress. However, it is possible that splitting
- // another live range will insert copies into a peripheral block, and
- // there is a small chance we can enter an infinite loop, inserting copies
- // forever.
- // For safety, stick to splitting live ranges with uses outside the
- // periphery.
- DEBUG(dbgs() << ": multiple peripheral uses");
- break;
- case ContainedInLoop:
- DEBUG(dbgs() << ": fully contained\n");
- continue;
- case SinglePeripheral:
- DEBUG(dbgs() << ": single peripheral use\n");
- continue;
- }
- // Will it be possible to split around this loop?
- getCriticalExits(Blocks, CriticalExits);
- DEBUG(dbgs() << ": " << CriticalExits.size() << " critical exits\n");
- if (!canSplitCriticalExits(Blocks, CriticalExits))
- continue;
- // This is a possible split.
- Loops.insert(Loop);
- }
-
- DEBUG(dbgs() << " getSplitLoops found " << Loops.size()
- << " candidate loops.\n");
+ // Range does not contain Idx, previous must end at Idx.
+ return I != Orig.begin() && (--I)->end == Idx;
}
-const MachineLoop *SplitAnalysis::getBestSplitLoop() {
- LoopPtrSet Loops;
- getSplitLoops(Loops);
- if (Loops.empty())
- return 0;
-
- // Pick the earliest loop.
- // FIXME: Are there other heuristics to consider?
- const MachineLoop *Best = 0;
- SlotIndex BestIdx;
- for (LoopPtrSet::const_iterator I = Loops.begin(), E = Loops.end(); I != E;
- ++I) {
- SlotIndex Idx = LIS.getMBBStartIdx((*I)->getHeader());
- if (!Best || Idx < BestIdx)
- Best = *I, BestIdx = Idx;
+void SplitAnalysis::print(const BlockPtrSet &B, raw_ostream &OS) const {
+ for (BlockPtrSet::const_iterator I = B.begin(), E = B.end(); I != E; ++I) {
+ unsigned count = UsingBlocks.lookup(*I);
+ OS << " BB#" << (*I)->getNumber();
+ if (count)
+ OS << '(' << count << ')';
}
- DEBUG(dbgs() << " getBestSplitLoop found " << *Best);
- return Best;
-}
-
-/// isBypassLoop - Return true if CurLI is live through Loop and has no uses
-/// inside the loop. Bypass loops are candidates for splitting because it can
-/// prevent interference inside the loop.
-bool SplitAnalysis::isBypassLoop(const MachineLoop *Loop) {
- // If CurLI is live into the loop header and there are no uses in the loop, it
- // must be live in the entire loop and live on at least one exiting edge.
- return !UsingLoops.count(Loop) &&
- LIS.isLiveInToMBB(*CurLI, Loop->getHeader());
}
-/// getBypassLoops - Get all the maximal bypass loops. These are the bypass
-/// loops whose parent is not a bypass loop.
-void SplitAnalysis::getBypassLoops(LoopPtrSet &BypassLoops) {
- SmallVector<MachineLoop*, 8> Todo(Loops.begin(), Loops.end());
- while (!Todo.empty()) {
- MachineLoop *Loop = Todo.pop_back_val();
- if (!UsingLoops.count(Loop)) {
- // This is either a bypass loop or completely irrelevant.
- if (LIS.isLiveInToMBB(*CurLI, Loop->getHeader()))
- BypassLoops.insert(Loop);
- // Either way, skip the child loops.
- continue;
- }
-
- // The child loops may be bypass loops.
- Todo.append(Loop->begin(), Loop->end());
- }
+void SplitAnalysis::analyze(const LiveInterval *li) {
+ clear();
+ CurLI = li;
+ analyzeUses();
}
//===----------------------------------------------------------------------===//
-// LiveIntervalMap
+// Split Editor
//===----------------------------------------------------------------------===//
-// Work around the fact that the std::pair constructors are broken for pointer
-// pairs in some implementations. makeVV(x, 0) works.
-static inline std::pair<const VNInfo*, VNInfo*>
-makeVV(const VNInfo *a, VNInfo *b) {
- return std::make_pair(a, b);
-}
+/// Create a new SplitEditor for editing the LiveInterval analyzed by SA.
+SplitEditor::SplitEditor(SplitAnalysis &sa,
+ LiveIntervals &lis,
+ VirtRegMap &vrm,
+ MachineDominatorTree &mdt)
+ : SA(sa), LIS(lis), VRM(vrm),
+ MRI(vrm.getMachineFunction().getRegInfo()),
+ MDT(mdt),
+ TII(*vrm.getMachineFunction().getTarget().getInstrInfo()),
+ TRI(*vrm.getMachineFunction().getTarget().getRegisterInfo()),
+ Edit(0),
+ OpenIdx(0),
+ RegAssign(Allocator)
+{}
-void LiveIntervalMap::reset(LiveInterval *li) {
- LI = li;
+void SplitEditor::reset(LiveRangeEdit &lre) {
+ Edit = &lre;
+ OpenIdx = 0;
+ RegAssign.clear();
Values.clear();
- LiveOutCache.clear();
+
+ // We don't need to clear LiveOutCache, only LiveOutSeen entries are read.
+ LiveOutSeen.clear();
+
+ // We don't need an AliasAnalysis since we will only be performing
+ // cheap-as-a-copy remats anyway.
+ Edit->anyRematerializable(LIS, TII, 0);
}
-bool LiveIntervalMap::isComplexMapped(const VNInfo *ParentVNI) const {
- ValueMap::const_iterator i = Values.find(ParentVNI);
- return i != Values.end() && i->second == 0;
+void SplitEditor::dump() const {
+ if (RegAssign.empty()) {
+ dbgs() << " empty\n";
+ return;
+ }
+
+ for (RegAssignMap::const_iterator I = RegAssign.begin(); I.valid(); ++I)
+ dbgs() << " [" << I.start() << ';' << I.stop() << "):" << I.value();
+ dbgs() << '\n';
}
-// defValue - Introduce a LI def for ParentVNI that could be later than
-// ParentVNI->def.
-VNInfo *LiveIntervalMap::defValue(const VNInfo *ParentVNI, SlotIndex Idx) {
- assert(LI && "call reset first");
+VNInfo *SplitEditor::defValue(unsigned RegIdx,
+ const VNInfo *ParentVNI,
+ SlotIndex Idx) {
assert(ParentVNI && "Mapping NULL value");
assert(Idx.isValid() && "Invalid SlotIndex");
- assert(ParentLI.getVNInfoAt(Idx) == ParentVNI && "Bad ParentVNI");
+ assert(Edit->getParent().getVNInfoAt(Idx) == ParentVNI && "Bad Parent VNI");
+ LiveInterval *LI = Edit->get(RegIdx);
// Create a new value.
VNInfo *VNI = LI->getNextValue(Idx, 0, LIS.getVNInfoAllocator());
- // Preserve the PHIDef bit.
- if (ParentVNI->isPHIDef() && Idx == ParentVNI->def)
- VNI->setIsPHIDef(true);
-
// Use insert for lookup, so we can add missing values with a second lookup.
- std::pair<ValueMap::iterator,bool> InsP =
- Values.insert(makeVV(ParentVNI, Idx == ParentVNI->def ? VNI : 0));
+ std::pair<ValueMap::iterator, bool> InsP =
+ Values.insert(std::make_pair(std::make_pair(RegIdx, ParentVNI->id), VNI));
+
+ // This was the first time (RegIdx, ParentVNI) was mapped.
+ // Keep it as a simple def without any liveness.
+ if (InsP.second)
+ return VNI;
- // This is now a complex def. Mark with a NULL in valueMap.
- if (!InsP.second)
+ // If the previous value was a simple mapping, add liveness for it now.
+ if (VNInfo *OldVNI = InsP.first->second) {
+ SlotIndex Def = OldVNI->def;
+ LI->addRange(LiveRange(Def, Def.getNextSlot(), OldVNI));
+ // No longer a simple mapping.
InsP.first->second = 0;
+ }
+
+ // This is a complex mapping, add liveness for VNI
+ SlotIndex Def = VNI->def;
+ LI->addRange(LiveRange(Def, Def.getNextSlot(), VNI));
return VNI;
}
-
-// mapValue - Find the mapped value for ParentVNI at Idx.
-// Potentially create phi-def values.
-VNInfo *LiveIntervalMap::mapValue(const VNInfo *ParentVNI, SlotIndex Idx,
- bool *simple) {
- assert(LI && "call reset first");
+void SplitEditor::markComplexMapped(unsigned RegIdx, const VNInfo *ParentVNI) {
assert(ParentVNI && "Mapping NULL value");
- assert(Idx.isValid() && "Invalid SlotIndex");
- assert(ParentLI.getVNInfoAt(Idx) == ParentVNI && "Bad ParentVNI");
+ VNInfo *&VNI = Values[std::make_pair(RegIdx, ParentVNI->id)];
- // Use insert for lookup, so we can add missing values with a second lookup.
- std::pair<ValueMap::iterator,bool> InsP =
- Values.insert(makeVV(ParentVNI, 0));
-
- // This was an unknown value. Create a simple mapping.
- if (InsP.second) {
- if (simple) *simple = true;
- return InsP.first->second = LI->createValueCopy(ParentVNI,
- LIS.getVNInfoAllocator());
- }
+ // ParentVNI was either unmapped or already complex mapped. Either way.
+ if (!VNI)
+ return;
- // This was a simple mapped value.
- if (InsP.first->second) {
- if (simple) *simple = true;
- return InsP.first->second;
- }
+ // This was previously a single mapping. Make sure the old def is represented
+ // by a trivial live range.
+ SlotIndex Def = VNI->def;
+ Edit->get(RegIdx)->addRange(LiveRange(Def, Def.getNextSlot(), VNI));
+ VNI = 0;
+}
- // This is a complex mapped value. There may be multiple defs, and we may need
- // to create phi-defs.
- if (simple) *simple = false;
+// extendRange - Extend the live range to reach Idx.
+// Potentially create phi-def values.
+void SplitEditor::extendRange(unsigned RegIdx, SlotIndex Idx) {
+ assert(Idx.isValid() && "Invalid SlotIndex");
MachineBasicBlock *IdxMBB = LIS.getMBBFromIndex(Idx);
assert(IdxMBB && "No MBB at Idx");
+ LiveInterval *LI = Edit->get(RegIdx);
// Is there a def in the same MBB we can extend?
- if (VNInfo *VNI = extendTo(IdxMBB, Idx))
- return VNI;
+ if (LI->extendInBlock(LIS.getMBBStartIdx(IdxMBB), Idx))
+ return;
// Now for the fun part. We know that ParentVNI potentially has multiple defs,
// and we may need to create even more phi-defs to preserve VNInfo SSA form.
// Perform a search for all predecessor blocks where we know the dominating
// VNInfo. Insert phi-def VNInfos along the path back to IdxMBB.
- DEBUG(dbgs() << "\n Reaching defs for BB#" << IdxMBB->getNumber()
- << " at " << Idx << " in " << *LI << '\n');
+
+ // Initialize the live-out cache the first time it is needed.
+ if (LiveOutSeen.empty()) {
+ unsigned N = VRM.getMachineFunction().getNumBlockIDs();
+ LiveOutSeen.resize(N);
+ LiveOutCache.resize(N);
+ }
// Blocks where LI should be live-in.
SmallVector<MachineDomTreeNode*, 16> LiveIn;
LiveIn.push_back(MDT[IdxMBB]);
+ // Remember if we have seen more than one value.
+ bool UniqueVNI = true;
+ VNInfo *IdxVNI = 0;
+
// Using LiveOutCache as a visited set, perform a BFS for all reaching defs.
for (unsigned i = 0; i != LiveIn.size(); ++i) {
MachineBasicBlock *MBB = LiveIn[i]->getBlock();
+ assert(!MBB->pred_empty() && "Value live-in to entry block?");
for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
PE = MBB->pred_end(); PI != PE; ++PI) {
MachineBasicBlock *Pred = *PI;
+ LiveOutPair &LOP = LiveOutCache[Pred];
+
// Is this a known live-out block?
- std::pair<LiveOutMap::iterator,bool> LOIP =
- LiveOutCache.insert(std::make_pair(Pred, LiveOutPair()));
- // Yes, we have been here before.
- if (!LOIP.second) {
- DEBUG(if (VNInfo *VNI = LOIP.first->second.first)
- dbgs() << " known valno #" << VNI->id
- << " at BB#" << Pred->getNumber() << '\n');
+ if (LiveOutSeen.test(Pred->getNumber())) {
+ if (VNInfo *VNI = LOP.first) {
+ if (IdxVNI && IdxVNI != VNI)
+ UniqueVNI = false;
+ IdxVNI = VNI;
+ }
continue;
}
+ // First time. LOP is garbage and must be cleared below.
+ LiveOutSeen.set(Pred->getNumber());
+
// Does Pred provide a live-out value?
- SlotIndex Last = LIS.getMBBEndIdx(Pred).getPrevSlot();
- if (VNInfo *VNI = extendTo(Pred, Last)) {
- MachineBasicBlock *DefMBB = LIS.getMBBFromIndex(VNI->def);
- DEBUG(dbgs() << " found valno #" << VNI->id
- << " from BB#" << DefMBB->getNumber()
- << " at BB#" << Pred->getNumber() << '\n');
- LiveOutPair &LOP = LOIP.first->second;
- LOP.first = VNI;
- LOP.second = MDT[DefMBB];
+ SlotIndex Start, Last;
+ tie(Start, Last) = LIS.getSlotIndexes()->getMBBRange(Pred);
+ Last = Last.getPrevSlot();
+ VNInfo *VNI = LI->extendInBlock(Start, Last);
+ LOP.first = VNI;
+ if (VNI) {
+ LOP.second = MDT[LIS.getMBBFromIndex(VNI->def)];
+ if (IdxVNI && IdxVNI != VNI)
+ UniqueVNI = false;
+ IdxVNI = VNI;
continue;
}
+ LOP.second = 0;
+
// No, we need a live-in value for Pred as well
if (Pred != IdxMBB)
LiveIn.push_back(MDT[Pred]);
+ else
+ UniqueVNI = false; // Loopback to IdxMBB, ask updateSSA() for help.
}
}
// We may need to add phi-def values to preserve the SSA form.
+ if (UniqueVNI) {
+ LiveOutPair LOP(IdxVNI, MDT[LIS.getMBBFromIndex(IdxVNI->def)]);
+ // Update LiveOutCache, but skip IdxMBB at LiveIn[0].
+ for (unsigned i = 1, e = LiveIn.size(); i != e; ++i)
+ LiveOutCache[LiveIn[i]->getBlock()] = LOP;
+ } else
+ IdxVNI = updateSSA(RegIdx, LiveIn, Idx, IdxMBB);
+
+ // Since we went through the trouble of a full BFS visiting all reaching defs,
+ // the values in LiveIn are now accurate. No more phi-defs are needed
+ // for these blocks, so we can color the live ranges.
+ for (unsigned i = 0, e = LiveIn.size(); i != e; ++i) {
+ MachineBasicBlock *MBB = LiveIn[i]->getBlock();
+ SlotIndex Start = LIS.getMBBStartIdx(MBB);
+ VNInfo *VNI = LiveOutCache[MBB].first;
+
+ // Anything in LiveIn other than IdxMBB is live-through.
+ // In IdxMBB, we should stop at Idx unless the same value is live-out.
+ if (MBB == IdxMBB && IdxVNI != VNI)
+ LI->addRange(LiveRange(Start, Idx.getNextSlot(), IdxVNI));
+ else
+ LI->addRange(LiveRange(Start, LIS.getMBBEndIdx(MBB), VNI));
+ }
+}
+
+VNInfo *SplitEditor::updateSSA(unsigned RegIdx,
+ SmallVectorImpl<MachineDomTreeNode*> &LiveIn,
+ SlotIndex Idx,
+ const MachineBasicBlock *IdxMBB) {
// This is essentially the same iterative algorithm that SSAUpdater uses,
// except we already have a dominator tree, so we don't have to recompute it.
+ LiveInterval *LI = Edit->get(RegIdx);
VNInfo *IdxVNI = 0;
unsigned Changes;
do {
Changes = 0;
- DEBUG(dbgs() << " Iterating over " << LiveIn.size() << " blocks.\n");
- // Propagate live-out values down the dominator tree, inserting phi-defs when
- // necessary. Since LiveIn was created by a BFS, going backwards makes it more
- // likely for us to visit immediate dominators before their children.
+ // Propagate live-out values down the dominator tree, inserting phi-defs
+ // when necessary. Since LiveIn was created by a BFS, going backwards makes
+ // it more likely for us to visit immediate dominators before their
+ // children.
for (unsigned i = LiveIn.size(); i; --i) {
MachineDomTreeNode *Node = LiveIn[i-1];
MachineBasicBlock *MBB = Node->getBlock();
MachineDomTreeNode *IDom = Node->getIDom();
LiveOutPair IDomValue;
+
// We need a live-in value to a block with no immediate dominator?
// This is probably an unreachable block that has survived somehow.
- bool needPHI = !IDom;
-
- // Get the IDom live-out value.
- if (!needPHI) {
- LiveOutMap::iterator I = LiveOutCache.find(IDom->getBlock());
- if (I != LiveOutCache.end())
- IDomValue = I->second;
- else
- // If IDom is outside our set of live-out blocks, there must be new
- // defs, and we need a phi-def here.
- needPHI = true;
- }
+ bool needPHI = !IDom || !LiveOutSeen.test(IDom->getBlock()->getNumber());
// IDom dominates all of our predecessors, but it may not be the immediate
// dominator. Check if any of them have live-out values that are properly
// dominated by IDom. If so, we need a phi-def here.
if (!needPHI) {
+ IDomValue = LiveOutCache[IDom->getBlock()];
for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
PE = MBB->pred_end(); PI != PE; ++PI) {
LiveOutPair Value = LiveOutCache[*PI];
SlotIndex Start = LIS.getMBBStartIdx(MBB);
VNInfo *VNI = LI->getNextValue(Start, 0, LIS.getVNInfoAllocator());
VNI->setIsPHIDef(true);
- DEBUG(dbgs() << " - BB#" << MBB->getNumber()
- << " phi-def #" << VNI->id << " at " << Start << '\n');
// We no longer need LI to be live-in.
LiveIn.erase(LiveIn.begin()+(i-1));
// Blocks in LiveIn are either IdxMBB, or have a value live-through.
if (MBB == IdxMBB)
IdxVNI = VNI;
// Check if we need to update live-out info.
- LiveOutMap::iterator I = LiveOutCache.find(MBB);
- if (I == LiveOutCache.end() || I->second.second == Node) {
+ LiveOutPair &LOP = LiveOutCache[MBB];
+ if (LOP.second == Node || !LiveOutSeen.test(MBB->getNumber())) {
// We already have a live-out defined in MBB, so this must be IdxMBB.
assert(MBB == IdxMBB && "Adding phi-def to known live-out");
LI->addRange(LiveRange(Start, Idx.getNextSlot(), VNI));
} else {
// This phi-def is also live-out, so color the whole block.
LI->addRange(LiveRange(Start, LIS.getMBBEndIdx(MBB), VNI));
- I->second = LiveOutPair(VNI, Node);
+ LOP = LiveOutPair(VNI, Node);
}
} else if (IDomValue.first) {
// No phi-def here. Remember incoming value for IdxMBB.
- if (MBB == IdxMBB)
+ if (MBB == IdxMBB) {
IdxVNI = IDomValue.first;
+ // IdxMBB need not be live-out.
+ if (!LiveOutSeen.test(MBB->getNumber()))
+ continue;
+ }
+ assert(LiveOutSeen.test(MBB->getNumber()) && "Expected live-out block");
// Propagate IDomValue if needed:
// MBB is live-out and doesn't define its own value.
- LiveOutMap::iterator I = LiveOutCache.find(MBB);
- if (I != LiveOutCache.end() && I->second.second != Node &&
- I->second.first != IDomValue.first) {
+ LiveOutPair &LOP = LiveOutCache[MBB];
+ if (LOP.second != Node && LOP.first != IDomValue.first) {
++Changes;
- I->second = IDomValue;
- DEBUG(dbgs() << " - BB#" << MBB->getNumber()
- << " idom valno #" << IDomValue.first->id
- << " from BB#" << IDom->getBlock()->getNumber() << '\n');
+ LOP = IDomValue;
}
}
}
- DEBUG(dbgs() << " - made " << Changes << " changes.\n");
} while (Changes);
assert(IdxVNI && "Didn't find value for Idx");
-
-#ifndef NDEBUG
- // Check the LiveOutCache invariants.
- for (LiveOutMap::iterator I = LiveOutCache.begin(), E = LiveOutCache.end();
- I != E; ++I) {
- assert(I->first && "Null MBB entry in cache");
- assert(I->second.first && "Null VNInfo in cache");
- assert(I->second.second && "Null DomTreeNode in cache");
- if (I->second.second->getBlock() == I->first)
- continue;
- for (MachineBasicBlock::pred_iterator PI = I->first->pred_begin(),
- PE = I->first->pred_end(); PI != PE; ++PI)
- assert(LiveOutCache.lookup(*PI) == I->second && "Bad invariant");
- }
-#endif
-
- // Since we went through the trouble of a full BFS visiting all reaching defs,
- // the values in LiveIn are now accurate. No more phi-defs are needed
- // for these blocks, so we can color the live ranges.
- // This makes the next mapValue call much faster.
- for (unsigned i = 0, e = LiveIn.size(); i != e; ++i) {
- MachineBasicBlock *MBB = LiveIn[i]->getBlock();
- SlotIndex Start = LIS.getMBBStartIdx(MBB);
- VNInfo *VNI = LiveOutCache.lookup(MBB).first;
-
- // Anything in LiveIn other than IdxMBB is live-through.
- // In IdxMBB, we should stop at Idx unless the same value is live-out.
- if (MBB == IdxMBB && IdxVNI != VNI)
- LI->addRange(LiveRange(Start, Idx.getNextSlot(), IdxVNI));
- else
- LI->addRange(LiveRange(Start, LIS.getMBBEndIdx(MBB), VNI));
- }
-
return IdxVNI;
}
-#ifndef NDEBUG
-void LiveIntervalMap::dumpCache() {
- for (LiveOutMap::iterator I = LiveOutCache.begin(), E = LiveOutCache.end();
- I != E; ++I) {
- assert(I->first && "Null MBB entry in cache");
- assert(I->second.first && "Null VNInfo in cache");
- assert(I->second.second && "Null DomTreeNode in cache");
- dbgs() << " cache: BB#" << I->first->getNumber()
- << " has valno #" << I->second.first->id << " from BB#"
- << I->second.second->getBlock()->getNumber() << ", preds";
- for (MachineBasicBlock::pred_iterator PI = I->first->pred_begin(),
- PE = I->first->pred_end(); PI != PE; ++PI)
- dbgs() << " BB#" << (*PI)->getNumber();
- dbgs() << '\n';
- }
- dbgs() << " cache: " << LiveOutCache.size() << " entries.\n";
-}
-#endif
-
-// extendTo - Find the last LI value defined in MBB at or before Idx. The
-// ParentLI is assumed to be live at Idx. Extend the live range to Idx.
-// Return the found VNInfo, or NULL.
-VNInfo *LiveIntervalMap::extendTo(const MachineBasicBlock *MBB, SlotIndex Idx) {
- assert(LI && "call reset first");
- LiveInterval::iterator I = std::upper_bound(LI->begin(), LI->end(), Idx);
- if (I == LI->begin())
- return 0;
- --I;
- if (I->end <= LIS.getMBBStartIdx(MBB))
- return 0;
- if (I->end <= Idx)
- I->end = Idx.getNextSlot();
- return I->valno;
-}
-
-// addSimpleRange - Add a simple range from ParentLI to LI.
-// ParentVNI must be live in the [Start;End) interval.
-void LiveIntervalMap::addSimpleRange(SlotIndex Start, SlotIndex End,
- const VNInfo *ParentVNI) {
- assert(LI && "call reset first");
- bool simple;
- VNInfo *VNI = mapValue(ParentVNI, Start, &simple);
- // A simple mapping is easy.
- if (simple) {
- LI->addRange(LiveRange(Start, End, VNI));
- return;
- }
-
- // ParentVNI is a complex value. We must map per MBB.
- MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start);
- MachineFunction::iterator MBBE = LIS.getMBBFromIndex(End.getPrevSlot());
-
- if (MBB == MBBE) {
- LI->addRange(LiveRange(Start, End, VNI));
- return;
- }
-
- // First block.
- LI->addRange(LiveRange(Start, LIS.getMBBEndIdx(MBB), VNI));
-
- // Run sequence of full blocks.
- for (++MBB; MBB != MBBE; ++MBB) {
- Start = LIS.getMBBStartIdx(MBB);
- LI->addRange(LiveRange(Start, LIS.getMBBEndIdx(MBB),
- mapValue(ParentVNI, Start)));
- }
-
- // Final block.
- Start = LIS.getMBBStartIdx(MBB);
- if (Start != End)
- LI->addRange(LiveRange(Start, End, mapValue(ParentVNI, Start)));
-}
-
-/// addRange - Add live ranges to LI where [Start;End) intersects ParentLI.
-/// All needed values whose def is not inside [Start;End) must be defined
-/// beforehand so mapValue will work.
-void LiveIntervalMap::addRange(SlotIndex Start, SlotIndex End) {
- assert(LI && "call reset first");
- LiveInterval::const_iterator B = ParentLI.begin(), E = ParentLI.end();
- LiveInterval::const_iterator I = std::lower_bound(B, E, Start);
-
- // Check if --I begins before Start and overlaps.
- if (I != B) {
- --I;
- if (I->end > Start)
- addSimpleRange(Start, std::min(End, I->end), I->valno);
- ++I;
- }
-
- // The remaining ranges begin after Start.
- for (;I != E && I->start < End; ++I)
- addSimpleRange(I->start, std::min(End, I->end), I->valno);
-}
-
-
-//===----------------------------------------------------------------------===//
-// Split Editor
-//===----------------------------------------------------------------------===//
-
-/// Create a new SplitEditor for editing the LiveInterval analyzed by SA.
-SplitEditor::SplitEditor(SplitAnalysis &sa,
- LiveIntervals &lis,
- VirtRegMap &vrm,
- MachineDominatorTree &mdt,
- LiveRangeEdit &edit)
- : sa_(sa), LIS(lis), VRM(vrm),
- MRI(vrm.getMachineFunction().getRegInfo()),
- MDT(mdt),
- TII(*vrm.getMachineFunction().getTarget().getInstrInfo()),
- TRI(*vrm.getMachineFunction().getTarget().getRegisterInfo()),
- Edit(edit),
- OpenIdx(0),
- RegAssign(Allocator)
-{
- // We don't need an AliasAnalysis since we will only be performing
- // cheap-as-a-copy remats anyway.
- Edit.anyRematerializable(LIS, TII, 0);
-}
-
-void SplitEditor::dump() const {
- if (RegAssign.empty()) {
- dbgs() << " empty\n";
- return;
- }
-
- for (RegAssignMap::const_iterator I = RegAssign.begin(); I.valid(); ++I)
- dbgs() << " [" << I.start() << ';' << I.stop() << "):" << I.value();
- dbgs() << '\n';
-}
-
VNInfo *SplitEditor::defFromParent(unsigned RegIdx,
VNInfo *ParentVNI,
SlotIndex UseIdx,
MachineBasicBlock::iterator I) {
MachineInstr *CopyMI = 0;
SlotIndex Def;
- LiveInterval *LI = Edit.get(RegIdx);
+ LiveInterval *LI = Edit->get(RegIdx);
// Attempt cheap-as-a-copy rematerialization.
LiveRangeEdit::Remat RM(ParentVNI);
- if (Edit.canRematerializeAt(RM, UseIdx, true, LIS)) {
- Def = Edit.rematerializeAt(MBB, I, LI->reg, RM, LIS, TII, TRI);
+ if (Edit->canRematerializeAt(RM, UseIdx, true, LIS)) {
+ Def = Edit->rematerializeAt(MBB, I, LI->reg, RM, LIS, TII, TRI);
} else {
// Can't remat, just insert a copy from parent.
CopyMI = BuildMI(MBB, I, DebugLoc(), TII.get(TargetOpcode::COPY), LI->reg)
- .addReg(Edit.getReg());
+ .addReg(Edit->getReg());
Def = LIS.InsertMachineInstrInMaps(CopyMI).getDefIndex();
}
// Define the value in Reg.
- VNInfo *VNI = LIMappers[RegIdx].defValue(ParentVNI, Def);
+ VNInfo *VNI = defValue(RegIdx, ParentVNI, Def);
VNI->setCopy(CopyMI);
-
- // Add minimal liveness for the new value.
- Edit.get(RegIdx)->addRange(LiveRange(Def, Def.getNextSlot(), VNI));
return VNI;
}
assert(!OpenIdx && "Previous LI not closed before openIntv");
// Create the complement as index 0.
- if (Edit.empty()) {
- Edit.create(MRI, LIS, VRM);
- LIMappers.push_back(LiveIntervalMap(LIS, MDT, Edit.getParent()));
- LIMappers.back().reset(Edit.get(0));
- }
+ if (Edit->empty())
+ Edit->create(LIS, VRM);
// Create the open interval.
- OpenIdx = Edit.size();
- Edit.create(MRI, LIS, VRM);
- LIMappers.push_back(LiveIntervalMap(LIS, MDT, Edit.getParent()));
- LIMappers[OpenIdx].reset(Edit.get(OpenIdx));
+ OpenIdx = Edit->size();
+ Edit->create(LIS, VRM);
}
SlotIndex SplitEditor::enterIntvBefore(SlotIndex Idx) {
assert(OpenIdx && "openIntv not called before enterIntvBefore");
DEBUG(dbgs() << " enterIntvBefore " << Idx);
Idx = Idx.getBaseIndex();
- VNInfo *ParentVNI = Edit.getParent().getVNInfoAt(Idx);
+ VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Idx);
if (!ParentVNI) {
DEBUG(dbgs() << ": not live\n");
return Idx;
SlotIndex End = LIS.getMBBEndIdx(&MBB);
SlotIndex Last = End.getPrevSlot();
DEBUG(dbgs() << " enterIntvAtEnd BB#" << MBB.getNumber() << ", " << Last);
- VNInfo *ParentVNI = Edit.getParent().getVNInfoAt(Last);
+ VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Last);
if (!ParentVNI) {
DEBUG(dbgs() << ": not live\n");
return End;
}
DEBUG(dbgs() << ": valno " << ParentVNI->id);
VNInfo *VNI = defFromParent(OpenIdx, ParentVNI, Last, MBB,
- LIS.getLastSplitPoint(Edit.getParent(), &MBB));
+ LIS.getLastSplitPoint(Edit->getParent(), &MBB));
RegAssign.insert(VNI->def, End, OpenIdx);
DEBUG(dump());
return VNI->def;
// The interval must be live beyond the instruction at Idx.
Idx = Idx.getBoundaryIndex();
- VNInfo *ParentVNI = Edit.getParent().getVNInfoAt(Idx);
+ VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Idx);
if (!ParentVNI) {
DEBUG(dbgs() << ": not live\n");
return Idx.getNextSlot();
return VNI->def;
}
+SlotIndex SplitEditor::leaveIntvBefore(SlotIndex Idx) {
+ assert(OpenIdx && "openIntv not called before leaveIntvBefore");
+ DEBUG(dbgs() << " leaveIntvBefore " << Idx);
+
+ // The interval must be live into the instruction at Idx.
+ Idx = Idx.getBoundaryIndex();
+ VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Idx);
+ if (!ParentVNI) {
+ DEBUG(dbgs() << ": not live\n");
+ return Idx.getNextSlot();
+ }
+ DEBUG(dbgs() << ": valno " << ParentVNI->id << '\n');
+
+ MachineInstr *MI = LIS.getInstructionFromIndex(Idx);
+ assert(MI && "No instruction at index");
+ VNInfo *VNI = defFromParent(0, ParentVNI, Idx, *MI->getParent(), MI);
+ return VNI->def;
+}
+
SlotIndex SplitEditor::leaveIntvAtTop(MachineBasicBlock &MBB) {
assert(OpenIdx && "openIntv not called before leaveIntvAtTop");
SlotIndex Start = LIS.getMBBStartIdx(&MBB);
DEBUG(dbgs() << " leaveIntvAtTop BB#" << MBB.getNumber() << ", " << Start);
- VNInfo *ParentVNI = Edit.getParent().getVNInfoAt(Start);
+ VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Start);
if (!ParentVNI) {
DEBUG(dbgs() << ": not live\n");
return Start;
void SplitEditor::overlapIntv(SlotIndex Start, SlotIndex End) {
assert(OpenIdx && "openIntv not called before overlapIntv");
- assert(Edit.getParent().getVNInfoAt(Start) ==
- Edit.getParent().getVNInfoAt(End.getPrevSlot()) &&
+ const VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Start);
+ assert(ParentVNI == Edit->getParent().getVNInfoAt(End.getPrevSlot()) &&
"Parent changes value in extended range");
- assert(Edit.get(0)->getVNInfoAt(Start) && "Start must come from leaveIntv*");
assert(LIS.getMBBFromIndex(Start) == LIS.getMBBFromIndex(End) &&
"Range cannot span basic blocks");
- // Treat this as useIntv() for now. The complement interval will be extended
- // as needed by mapValue().
+ // The complement interval will be extended as needed by extendRange().
+ markComplexMapped(0, ParentVNI);
DEBUG(dbgs() << " overlapIntv [" << Start << ';' << End << "):");
RegAssign.insert(Start, End, OpenIdx);
DEBUG(dump());
OpenIdx = 0;
}
-/// rewriteAssigned - Rewrite all uses of Edit.getReg().
-void SplitEditor::rewriteAssigned() {
- for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(Edit.getReg()),
+/// transferSimpleValues - Transfer all simply defined values to the new live
+/// ranges.
+/// Values that were rematerialized or that have multiple defs are left alone.
+bool SplitEditor::transferSimpleValues() {
+ bool Skipped = false;
+ RegAssignMap::const_iterator AssignI = RegAssign.begin();
+ for (LiveInterval::const_iterator ParentI = Edit->getParent().begin(),
+ ParentE = Edit->getParent().end(); ParentI != ParentE; ++ParentI) {
+ DEBUG(dbgs() << " blit " << *ParentI << ':');
+ VNInfo *ParentVNI = ParentI->valno;
+ // RegAssign has holes where RegIdx 0 should be used.
+ SlotIndex Start = ParentI->start;
+ AssignI.advanceTo(Start);
+ do {
+ unsigned RegIdx;
+ SlotIndex End = ParentI->end;
+ if (!AssignI.valid()) {
+ RegIdx = 0;
+ } else if (AssignI.start() <= Start) {
+ RegIdx = AssignI.value();
+ if (AssignI.stop() < End) {
+ End = AssignI.stop();
+ ++AssignI;
+ }
+ } else {
+ RegIdx = 0;
+ End = std::min(End, AssignI.start());
+ }
+ DEBUG(dbgs() << " [" << Start << ';' << End << ")=" << RegIdx);
+ if (VNInfo *VNI = Values.lookup(std::make_pair(RegIdx, ParentVNI->id))) {
+ DEBUG(dbgs() << ':' << VNI->id);
+ Edit->get(RegIdx)->addRange(LiveRange(Start, End, VNI));
+ } else
+ Skipped = true;
+ Start = End;
+ } while (Start != ParentI->end);
+ DEBUG(dbgs() << '\n');
+ }
+ return Skipped;
+}
+
+void SplitEditor::extendPHIKillRanges() {
+ // Extend live ranges to be live-out for successor PHI values.
+ for (LiveInterval::const_vni_iterator I = Edit->getParent().vni_begin(),
+ E = Edit->getParent().vni_end(); I != E; ++I) {
+ const VNInfo *PHIVNI = *I;
+ if (PHIVNI->isUnused() || !PHIVNI->isPHIDef())
+ continue;
+ unsigned RegIdx = RegAssign.lookup(PHIVNI->def);
+ MachineBasicBlock *MBB = LIS.getMBBFromIndex(PHIVNI->def);
+ for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
+ PE = MBB->pred_end(); PI != PE; ++PI) {
+ SlotIndex End = LIS.getMBBEndIdx(*PI).getPrevSlot();
+ // The predecessor may not have a live-out value. That is OK, like an
+ // undef PHI operand.
+ if (Edit->getParent().liveAt(End)) {
+ assert(RegAssign.lookup(End) == RegIdx &&
+ "Different register assignment in phi predecessor");
+ extendRange(RegIdx, End);
+ }
+ }
+ }
+}
+
+/// rewriteAssigned - Rewrite all uses of Edit->getReg().
+void SplitEditor::rewriteAssigned(bool ExtendRanges) {
+ for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(Edit->getReg()),
RE = MRI.reg_end(); RI != RE;) {
MachineOperand &MO = RI.getOperand();
MachineInstr *MI = MO.getParent();
// <undef> operands don't really read the register, so just assign them to
// the complement.
if (MO.isUse() && MO.isUndef()) {
- MO.setReg(Edit.get(0)->reg);
+ MO.setReg(Edit->get(0)->reg);
continue;
}
SlotIndex Idx = LIS.getInstructionIndex(MI);
- Idx = MO.isUse() ? Idx.getUseIndex() : Idx.getDefIndex();
+ if (MO.isDef())
+ Idx = MO.isEarlyClobber() ? Idx.getUseIndex() : Idx.getDefIndex();
// Rewrite to the mapped register at Idx.
unsigned RegIdx = RegAssign.lookup(Idx);
- MO.setReg(Edit.get(RegIdx)->reg);
+ MO.setReg(Edit->get(RegIdx)->reg);
DEBUG(dbgs() << " rewr BB#" << MI->getParent()->getNumber() << '\t'
<< Idx << ':' << RegIdx << '\t' << *MI);
- // Extend liveness to Idx.
- const VNInfo *ParentVNI = Edit.getParent().getVNInfoAt(Idx);
- LIMappers[RegIdx].mapValue(ParentVNI, Idx);
+ // Extend liveness to Idx if the instruction reads reg.
+ if (!ExtendRanges)
+ continue;
+
+ // Skip instructions that don't read Reg.
+ if (MO.isDef()) {
+ if (!MO.getSubReg() && !MO.isEarlyClobber())
+ continue;
+ // We may wan't to extend a live range for a partial redef, or for a use
+ // tied to an early clobber.
+ Idx = Idx.getPrevSlot();
+ if (!Edit->getParent().liveAt(Idx))
+ continue;
+ } else
+ Idx = Idx.getUseIndex();
+
+ extendRange(RegIdx, Idx);
}
}
-/// rewriteSplit - Rewrite uses of Intvs[0] according to the ConEQ mapping.
-void SplitEditor::rewriteComponents(const SmallVectorImpl<LiveInterval*> &Intvs,
- const ConnectedVNInfoEqClasses &ConEq) {
- for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(Intvs[0]->reg),
- RE = MRI.reg_end(); RI != RE;) {
- MachineOperand &MO = RI.getOperand();
- MachineInstr *MI = MO.getParent();
- ++RI;
- if (MO.isUse() && MO.isUndef())
- continue;
- // DBG_VALUE instructions should have been eliminated earlier.
- SlotIndex Idx = LIS.getInstructionIndex(MI);
- Idx = MO.isUse() ? Idx.getUseIndex() : Idx.getDefIndex();
- DEBUG(dbgs() << " rewr BB#" << MI->getParent()->getNumber() << '\t'
- << Idx << ':');
- const VNInfo *VNI = Intvs[0]->getVNInfoAt(Idx);
- assert(VNI && "Interval not live at use.");
- MO.setReg(Intvs[ConEq.getEqClass(VNI)]->reg);
- DEBUG(dbgs() << VNI->id << '\t' << *MI);
+void SplitEditor::deleteRematVictims() {
+ SmallVector<MachineInstr*, 8> Dead;
+ for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I){
+ LiveInterval *LI = *I;
+ for (LiveInterval::const_iterator LII = LI->begin(), LIE = LI->end();
+ LII != LIE; ++LII) {
+ // Dead defs end at the store slot.
+ if (LII->end != LII->valno->def.getNextSlot())
+ continue;
+ MachineInstr *MI = LIS.getInstructionFromIndex(LII->valno->def);
+ assert(MI && "Missing instruction for dead def");
+ MI->addRegisterDead(LI->reg, &TRI);
+
+ if (!MI->allDefsAreDead())
+ continue;
+
+ DEBUG(dbgs() << "All defs dead: " << *MI);
+ Dead.push_back(MI);
+ }
}
+
+ if (Dead.empty())
+ return;
+
+ Edit->eliminateDeadDefs(Dead, LIS, VRM, TII);
}
void SplitEditor::finish() {
assert(OpenIdx == 0 && "Previous LI not closed before rewrite");
+ ++NumFinished;
// At this point, the live intervals in Edit contain VNInfos corresponding to
// the inserted copies.
// Add the original defs from the parent interval.
- for (LiveInterval::const_vni_iterator I = Edit.getParent().vni_begin(),
- E = Edit.getParent().vni_end(); I != E; ++I) {
+ for (LiveInterval::const_vni_iterator I = Edit->getParent().vni_begin(),
+ E = Edit->getParent().vni_end(); I != E; ++I) {
const VNInfo *ParentVNI = *I;
if (ParentVNI->isUnused())
continue;
- LiveIntervalMap &LIM = LIMappers[RegAssign.lookup(ParentVNI->def)];
- VNInfo *VNI = LIM.defValue(ParentVNI, ParentVNI->def);
- LIM.getLI()->addRange(LiveRange(ParentVNI->def,
- ParentVNI->def.getNextSlot(), VNI));
- // Mark all values as complex to force liveness computation.
- // This should really only be necessary for remat victims, but we are lazy.
- LIM.markComplexMapped(ParentVNI);
+ unsigned RegIdx = RegAssign.lookup(ParentVNI->def);
+ VNInfo *VNI = defValue(RegIdx, ParentVNI, ParentVNI->def);
+ VNI->setIsPHIDef(ParentVNI->isPHIDef());
+ VNI->setCopy(ParentVNI->getCopy());
+
+ // Mark rematted values as complex everywhere to force liveness computation.
+ // The new live ranges may be truncated.
+ if (Edit->didRematerialize(ParentVNI))
+ for (unsigned i = 0, e = Edit->size(); i != e; ++i)
+ markComplexMapped(i, ParentVNI);
}
#ifndef NDEBUG
// Every new interval must have a def by now, otherwise the split is bogus.
- for (LiveRangeEdit::iterator I = Edit.begin(), E = Edit.end(); I != E; ++I)
+ for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I)
assert((*I)->hasAtLeastOneValue() && "Split interval has no value");
#endif
- // FIXME: Don't recompute the liveness of all values, infer it from the
- // overlaps between the parent live interval and RegAssign.
- // The mapValue algorithm is only necessary when:
- // - The parent value maps to multiple defs, and new phis are needed, or
- // - The value has been rematerialized before some uses, and we want to
- // minimize the live range so it only reaches the remaining uses.
- // All other values have simple liveness that can be computed from RegAssign
- // and the parent live interval.
-
- // Extend live ranges to be live-out for successor PHI values.
- for (LiveInterval::const_vni_iterator I = Edit.getParent().vni_begin(),
- E = Edit.getParent().vni_end(); I != E; ++I) {
- const VNInfo *PHIVNI = *I;
- if (PHIVNI->isUnused() || !PHIVNI->isPHIDef())
- continue;
- unsigned RegIdx = RegAssign.lookup(PHIVNI->def);
- LiveIntervalMap &LIM = LIMappers[RegIdx];
- MachineBasicBlock *MBB = LIS.getMBBFromIndex(PHIVNI->def);
- DEBUG(dbgs() << " map phi in BB#" << MBB->getNumber() << '@' << PHIVNI->def
- << " -> " << RegIdx << '\n');
- for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
- PE = MBB->pred_end(); PI != PE; ++PI) {
- SlotIndex End = LIS.getMBBEndIdx(*PI).getPrevSlot();
- DEBUG(dbgs() << " pred BB#" << (*PI)->getNumber() << '@' << End);
- // The predecessor may not have a live-out value. That is OK, like an
- // undef PHI operand.
- if (VNInfo *VNI = Edit.getParent().getVNInfoAt(End)) {
- DEBUG(dbgs() << " has parent valno #" << VNI->id << " live out\n");
- assert(RegAssign.lookup(End) == RegIdx &&
- "Different register assignment in phi predecessor");
- LIM.mapValue(VNI, End);
- }
- else
- DEBUG(dbgs() << " is not live-out\n");
- }
- DEBUG(dbgs() << " " << *LIM.getLI() << '\n');
- }
+ // Transfer the simply mapped values, check if any are complex.
+ bool Complex = transferSimpleValues();
+ if (Complex)
+ extendPHIKillRanges();
+ else
+ ++NumSimple;
- // Rewrite instructions.
- rewriteAssigned();
+ // Rewrite virtual registers, possibly extending ranges.
+ rewriteAssigned(Complex);
- // FIXME: Delete defs that were rematted everywhere.
+ // Delete defs that were rematted everywhere.
+ if (Complex)
+ deleteRematVictims();
// Get rid of unused values and set phi-kill flags.
- for (LiveRangeEdit::iterator I = Edit.begin(), E = Edit.end(); I != E; ++I)
+ for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I)
(*I)->RenumberValues(LIS);
// Now check if any registers were separated into multiple components.
ConnectedVNInfoEqClasses ConEQ(LIS);
- for (unsigned i = 0, e = Edit.size(); i != e; ++i) {
+ for (unsigned i = 0, e = Edit->size(); i != e; ++i) {
// Don't use iterators, they are invalidated by create() below.
- LiveInterval *li = Edit.get(i);
+ LiveInterval *li = Edit->get(i);
unsigned NumComp = ConEQ.Classify(li);
if (NumComp <= 1)
continue;
SmallVector<LiveInterval*, 8> dups;
dups.push_back(li);
for (unsigned i = 1; i != NumComp; ++i)
- dups.push_back(&Edit.create(MRI, LIS, VRM));
- rewriteComponents(dups, ConEQ);
- ConEQ.Distribute(&dups[0]);
+ dups.push_back(&Edit->create(LIS, VRM));
+ ConEQ.Distribute(&dups[0], MRI);
}
// Calculate spill weight and allocation hints for new intervals.
- VirtRegAuxInfo vrai(VRM.getMachineFunction(), LIS, sa_.Loops);
- for (LiveRangeEdit::iterator I = Edit.begin(), E = Edit.end(); I != E; ++I){
+ VirtRegAuxInfo vrai(VRM.getMachineFunction(), LIS, SA.Loops);
+ for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I){
LiveInterval &li = **I;
vrai.CalculateRegClass(li.reg);
vrai.CalculateWeightAndHint(li);
}
-//===----------------------------------------------------------------------===//
-// Loop Splitting
-//===----------------------------------------------------------------------===//
-
-void SplitEditor::splitAroundLoop(const MachineLoop *Loop) {
- SplitAnalysis::LoopBlocks Blocks;
- sa_.getLoopBlocks(Loop, Blocks);
-
- DEBUG({
- dbgs() << " splitAround"; sa_.print(Blocks, dbgs()); dbgs() << '\n';
- });
-
- // Break critical edges as needed.
- SplitAnalysis::BlockPtrSet CriticalExits;
- sa_.getCriticalExits(Blocks, CriticalExits);
- assert(CriticalExits.empty() && "Cannot break critical exits yet");
-
- // Create new live interval for the loop.
- openIntv();
-
- // Insert copies in the predecessors if live-in to the header.
- if (LIS.isLiveInToMBB(Edit.getParent(), Loop->getHeader())) {
- for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Preds.begin(),
- E = Blocks.Preds.end(); I != E; ++I) {
- MachineBasicBlock &MBB = const_cast<MachineBasicBlock&>(**I);
- enterIntvAtEnd(MBB);
- }
- }
-
- // Switch all loop blocks.
- for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Loop.begin(),
- E = Blocks.Loop.end(); I != E; ++I)
- useIntv(**I);
-
- // Insert back copies in the exit blocks.
- for (SplitAnalysis::BlockPtrSet::iterator I = Blocks.Exits.begin(),
- E = Blocks.Exits.end(); I != E; ++I) {
- MachineBasicBlock &MBB = const_cast<MachineBasicBlock&>(**I);
- leaveIntvAtTop(MBB);
- }
-
- // Done.
- closeIntv();
- finish();
-}
-
-
//===----------------------------------------------------------------------===//
// Single Block Splitting
//===----------------------------------------------------------------------===//
/// may be an advantage to split CurLI for the duration of the block.
bool SplitAnalysis::getMultiUseBlocks(BlockPtrSet &Blocks) {
// If CurLI is local to one block, there is no point to splitting it.
- if (UsingBlocks.size() <= 1)
+ if (LiveBlocks.size() <= 1)
return false;
// Add blocks with multiple uses.
- for (BlockCountMap::iterator I = UsingBlocks.begin(), E = UsingBlocks.end();
- I != E; ++I)
- switch (I->second) {
- case 0:
- case 1:
+ for (unsigned i = 0, e = LiveBlocks.size(); i != e; ++i) {
+ const BlockInfo &BI = LiveBlocks[i];
+ if (!BI.Uses)
continue;
- case 2: {
- // When there are only two uses and CurLI is both live in and live out,
- // we don't really win anything by isolating the block since we would be
- // inserting two copies.
- // The remaing register would still have two uses in the block. (Unless it
- // separates into disconnected components).
- if (LIS.isLiveInToMBB(*CurLI, I->first) &&
- LIS.isLiveOutOfMBB(*CurLI, I->first))
- continue;
- } // Fall through.
- default:
- Blocks.insert(I->first);
- }
+ unsigned Instrs = UsingBlocks.lookup(BI.MBB);
+ if (Instrs <= 1)
+ continue;
+ if (Instrs == 2 && BI.LiveIn && BI.LiveOut && !BI.LiveThrough)
+ continue;
+ Blocks.insert(BI.MBB);
+ }
return !Blocks.empty();
}
/// basic block in Blocks.
void SplitEditor::splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks) {
DEBUG(dbgs() << " splitSingleBlocks for " << Blocks.size() << " blocks.\n");
- // Determine the first and last instruction using CurLI in each block.
- typedef std::pair<SlotIndex,SlotIndex> IndexPair;
- typedef DenseMap<const MachineBasicBlock*,IndexPair> IndexPairMap;
- IndexPairMap MBBRange;
- for (SplitAnalysis::InstrPtrSet::const_iterator I = sa_.UsingInstrs.begin(),
- E = sa_.UsingInstrs.end(); I != E; ++I) {
- const MachineBasicBlock *MBB = (*I)->getParent();
- if (!Blocks.count(MBB))
- continue;
- SlotIndex Idx = LIS.getInstructionIndex(*I);
- DEBUG(dbgs() << " BB#" << MBB->getNumber() << '\t' << Idx << '\t' << **I);
- IndexPair &IP = MBBRange[MBB];
- if (!IP.first.isValid() || Idx < IP.first)
- IP.first = Idx;
- if (!IP.second.isValid() || Idx > IP.second)
- IP.second = Idx;
- }
- // Create a new interval for each block.
- for (SplitAnalysis::BlockPtrSet::const_iterator I = Blocks.begin(),
- E = Blocks.end(); I != E; ++I) {
- IndexPair &IP = MBBRange[*I];
- DEBUG(dbgs() << " splitting for BB#" << (*I)->getNumber() << ": ["
- << IP.first << ';' << IP.second << ")\n");
- assert(IP.first.isValid() && IP.second.isValid());
-
- openIntv();
- useIntv(enterIntvBefore(IP.first), leaveIntvAfter(IP.second));
- closeIntv();
- }
- finish();
-}
-
-
-//===----------------------------------------------------------------------===//
-// Sub Block Splitting
-//===----------------------------------------------------------------------===//
-
-/// getBlockForInsideSplit - If CurLI is contained inside a single basic block,
-/// and it wou pay to subdivide the interval inside that block, return it.
-/// Otherwise return NULL. The returned block can be passed to
-/// SplitEditor::splitInsideBlock.
-const MachineBasicBlock *SplitAnalysis::getBlockForInsideSplit() {
- // The interval must be exclusive to one block.
- if (UsingBlocks.size() != 1)
- return 0;
- // Don't to this for less than 4 instructions. We want to be sure that
- // splitting actually reduces the instruction count per interval.
- if (UsingInstrs.size() < 4)
- return 0;
- return UsingBlocks.begin()->first;
-}
-
-/// splitInsideBlock - Split CurLI into multiple intervals inside MBB.
-void SplitEditor::splitInsideBlock(const MachineBasicBlock *MBB) {
- SmallVector<SlotIndex, 32> Uses;
- Uses.reserve(sa_.UsingInstrs.size());
- for (SplitAnalysis::InstrPtrSet::const_iterator I = sa_.UsingInstrs.begin(),
- E = sa_.UsingInstrs.end(); I != E; ++I)
- if ((*I)->getParent() == MBB)
- Uses.push_back(LIS.getInstructionIndex(*I));
- DEBUG(dbgs() << " splitInsideBlock BB#" << MBB->getNumber() << " for "
- << Uses.size() << " instructions.\n");
- assert(Uses.size() >= 3 && "Need at least 3 instructions");
- array_pod_sort(Uses.begin(), Uses.end());
-
- // Simple algorithm: Find the largest gap between uses as determined by slot
- // indices. Create new intervals for instructions before the gap and after the
- // gap.
- unsigned bestPos = 0;
- int bestGap = 0;
- DEBUG(dbgs() << " dist (" << Uses[0]);
- for (unsigned i = 1, e = Uses.size(); i != e; ++i) {
- int g = Uses[i-1].distance(Uses[i]);
- DEBUG(dbgs() << ") -" << g << "- (" << Uses[i]);
- if (g > bestGap)
- bestPos = i, bestGap = g;
- }
- DEBUG(dbgs() << "), best: -" << bestGap << "-\n");
-
- // bestPos points to the first use after the best gap.
- assert(bestPos > 0 && "Invalid gap");
-
- // FIXME: Don't create intervals for low densities.
-
- // First interval before the gap. Don't create single-instr intervals.
- if (bestPos > 1) {
- openIntv();
- useIntv(enterIntvBefore(Uses.front()), leaveIntvAfter(Uses[bestPos-1]));
- closeIntv();
- }
+ for (unsigned i = 0, e = SA.LiveBlocks.size(); i != e; ++i) {
+ const SplitAnalysis::BlockInfo &BI = SA.LiveBlocks[i];
+ if (!BI.Uses || !Blocks.count(BI.MBB))
+ continue;
- // Second interval after the gap.
- if (bestPos < Uses.size()-1) {
openIntv();
- useIntv(enterIntvBefore(Uses[bestPos]), leaveIntvAfter(Uses.back()));
+ SlotIndex SegStart = enterIntvBefore(std::min(BI.FirstUse,
+ BI.LastSplitPoint));
+ if (!BI.LiveOut || BI.LastUse < BI.LastSplitPoint) {
+ useIntv(SegStart, leaveIntvAfter(BI.LastUse));
+ } else {
+ // The last use is after the last valid split point.
+ SlotIndex SegStop = leaveIntvBefore(BI.LastSplitPoint);
+ useIntv(SegStart, SegStop);
+ overlapIntv(SegStop, BI.LastUse);
+ }
closeIntv();
}
-
finish();
}
projects / oota-llvm.git / blobdiff