//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "splitter"
+#define DEBUG_TYPE "regalloc"
#include "SplitKit.h"
+#include "LiveRangeEdit.h"
+#include "VirtRegMap.h"
+#include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
-#include "llvm/CodeGen/MachineFunctionPass.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"
// Split Analysis
//===----------------------------------------------------------------------===//
-SplitAnalysis::SplitAnalysis(const MachineFunction *mf,
- const LiveIntervals *lis,
- const MachineLoopInfo *mli)
- : mf_(*mf),
- lis_(*lis),
- loops_(*mli),
- tii_(*mf->getTarget().getInstrInfo()),
+SplitAnalysis::SplitAnalysis(const MachineFunction &mf,
+ const LiveIntervals &lis,
+ const MachineLoopInfo &mli)
+ : mf_(mf),
+ lis_(lis),
+ loops_(mli),
+ tii_(*mf.getTarget().getInstrInfo()),
curli_(0) {}
void SplitAnalysis::clear() {
usingInstrs_.clear();
usingBlocks_.clear();
usingLoops_.clear();
+ curli_ = 0;
}
bool SplitAnalysis::canAnalyzeBranch(const MachineBasicBlock *MBB) {
MachineBasicBlock *MBB = MI->getParent();
if (usingBlocks_[MBB]++)
continue;
- if (MachineLoop *Loop = loops_.getLoopFor(MBB))
- usingLoops_.insert(Loop);
+ for (MachineLoop *Loop = loops_.getLoopFor(MBB); Loop;
+ Loop = Loop->getParentLoop())
+ usingLoops_[Loop]++;
}
- DEBUG(dbgs() << "Counted "
+ DEBUG(dbgs() << " counted "
<< usingInstrs_.size() << " instrs, "
<< usingBlocks_.size() << " blocks, "
- << usingLoops_.size() << " loops in "
- << *curli_ << "\n");
+ << 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,
}
}
+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::
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 phi uses of curli. Collect the exit
-/// blocks that need special treatment into CriticalExits.
+/// 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 contains a phi def of curli, 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.
+ // 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 *Succ = *I;
- SlotIndex SuccIdx = lis_.getMBBStartIdx(Succ);
- VNInfo *SuccVNI = curli_->getVNInfoAt(SuccIdx);
- // This exit may not have curli live in at all. No need to split.
- if (!SuccVNI)
+ const MachineBasicBlock *Exit = *I;
+ // A single-predecessor exit block is definitely not a critical edge.
+ if (Exit->pred_size() == 1)
continue;
- // If this is not a PHI def, it is either using a value from before the
- // loop, or a value defined inside the loop. Both are safe.
- if (!SuccVNI->isPHIDef() || SuccVNI->def.getBaseIndex() != SuccIdx)
+ // This exit may not have curli live in at all. No need to split.
+ if (!lis_.isLiveInToMBB(*curli_, Exit))
continue;
- // This exit block does have a PHI. Does it also have a predecessor that is
- // not a loop block or loop predecessor?
- for (MachineBasicBlock::const_pred_iterator PI = Succ->pred_begin(),
- PE = Succ->pred_end(); PI != PE; ++PI) {
+ // 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(Succ);
+ CriticalExits.insert(Exit);
+ break;
+ }
+ }
+}
+
+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);
break;
}
}
if (usingLoops_.empty())
return 0;
- LoopPtrSet Loops, SecondLoops;
+ LoopPtrSet Loops;
LoopBlocks Blocks;
BlockPtrSet CriticalExits;
- // Find first-class and second class candidate loops.
- // We prefer to split around loops where curli is used outside the periphery.
- for (LoopPtrSet::const_iterator I = usingLoops_.begin(),
+ // We split around loops where curli is used outside the periphery.
+ for (LoopCountMap::const_iterator I = usingLoops_.begin(),
E = usingLoops_.end(); I != E; ++I) {
- getLoopBlocks(*I, Blocks);
- LoopPtrSet *LPS = 0;
+ const MachineLoop *Loop = I->first;
+ getLoopBlocks(Loop, Blocks);
+ DEBUG({ dbgs() << " "; print(Blocks, dbgs()); });
+
switch(analyzeLoopPeripheralUse(Blocks)) {
case OutsideLoop:
- LPS = &Loops;
break;
case MultiPeripheral:
- LPS = &SecondLoops;
+ // 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 infinity loop, inserting copies
+ // forever.
+ // For safety, stick to splitting live ranges with uses outside the
+ // periphery.
+ DEBUG(dbgs() << ": multiple peripheral uses\n");
break;
case ContainedInLoop:
- DEBUG(dbgs() << "ContainedInLoop: " << **I);
+ DEBUG(dbgs() << ": fully contained\n");
continue;
case SinglePeripheral:
- DEBUG(dbgs() << "SinglePeripheral: " << **I);
+ 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: " << **I);
+ DEBUG(dbgs() << ": " << CriticalExits.size() << " critical exits\n");
if (!canSplitCriticalExits(Blocks, CriticalExits))
continue;
// This is a possible split.
- assert(LPS);
- LPS->insert(*I);
+ Loops.insert(Loop);
}
- DEBUG(dbgs() << "Got " << Loops.size() << " + " << SecondLoops.size()
- << " candidate loops\n");
-
- // If there are no first class loops available, look at second class loops.
- if (Loops.empty())
- Loops = SecondLoops;
+ DEBUG(dbgs() << " getBestSplitLoop found " << Loops.size()
+ << " candidate loops.\n");
if (Loops.empty())
return 0;
if (!Best || Idx < BestIdx)
Best = *I, BestIdx = Idx;
}
- DEBUG(dbgs() << "Best: " << *Best);
+ DEBUG(dbgs() << " getBestSplitLoop found " << *Best);
return Best;
}
//===----------------------------------------------------------------------===//
-// Loop Splitting
+// LiveIntervalMap
+//===----------------------------------------------------------------------===//
+
+// 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);
+}
+
+void LiveIntervalMap::reset(LiveInterval *li) {
+ li_ = li;
+ valueMap_.clear();
+ liveOutCache_.clear();
+}
+
+bool LiveIntervalMap::isComplexMapped(const VNInfo *ParentVNI) const {
+ ValueMap::const_iterator i = valueMap_.find(ParentVNI);
+ return i != valueMap_.end() && i->second == 0;
+}
+
+// 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");
+ assert(ParentVNI && "Mapping NULL value");
+ assert(Idx.isValid() && "Invalid SlotIndex");
+ assert(parentli_.getVNInfoAt(Idx) == ParentVNI && "Bad ParentVNI");
+
+ // 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 =
+ valueMap_.insert(makeVV(ParentVNI, Idx == ParentVNI->def ? VNI : 0));
+
+ // This is now a complex def. Mark with a NULL in valueMap.
+ if (!InsP.second)
+ InsP.first->second = 0;
+
+ 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");
+ assert(ParentVNI && "Mapping NULL value");
+ assert(Idx.isValid() && "Invalid SlotIndex");
+ assert(parentli_.getVNInfoAt(Idx) == ParentVNI && "Bad ParentVNI");
+
+ // Use insert for lookup, so we can add missing values with a second lookup.
+ std::pair<ValueMap::iterator,bool> InsP =
+ valueMap_.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());
+ }
+
+ // This was a simple mapped value.
+ if (InsP.first->second) {
+ if (simple) *simple = true;
+ return InsP.first->second;
+ }
+
+ // This is a complex mapped value. There may be multiple defs, and we may need
+ // to create phi-defs.
+ if (simple) *simple = false;
+ MachineBasicBlock *IdxMBB = lis_.getMBBFromIndex(Idx);
+ assert(IdxMBB && "No MBB at Idx");
+
+ // Is there a def in the same MBB we can extend?
+ if (VNInfo *VNI = extendTo(IdxMBB, Idx))
+ return VNI;
+
+ // 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');
+
+ // Blocks where li_ should be live-in.
+ SmallVector<MachineDomTreeNode*, 16> LiveIn;
+ LiveIn.push_back(mdt_[IdxMBB]);
+
+ // 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();
+ for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
+ PE = MBB->pred_end(); PI != PE; ++PI) {
+ MachineBasicBlock *Pred = *PI;
+ // 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');
+ continue;
+ }
+
+ // 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];
+ continue;
+ }
+ // No, we need a live-in value for Pred as well
+ if (Pred != IdxMBB)
+ LiveIn.push_back(mdt_[Pred]);
+ }
+ }
+
+ // We may need to add phi-def values to preserve the SSA form.
+ // 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.
+ 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.
+ 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;
+ }
+
+ // 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) {
+ for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
+ PE = MBB->pred_end(); PI != PE; ++PI) {
+ LiveOutPair Value = liveOutCache_[*PI];
+ if (!Value.first || Value.first == IDomValue.first)
+ continue;
+ // This predecessor is carrying something other than IDomValue.
+ // It could be because IDomValue hasn't propagated yet, or it could be
+ // because MBB is in the dominance frontier of that value.
+ if (mdt_.dominates(IDom, Value.second)) {
+ needPHI = true;
+ break;
+ }
+ }
+ }
+
+ // Create a phi-def if required.
+ if (needPHI) {
+ ++Changes;
+ 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) {
+ // 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);
+ }
+ } else if (IDomValue.first) {
+ // No phi-def here. Remember incoming value for IdxMBB.
+ if (MBB == IdxMBB)
+ IdxVNI = IDomValue.first;
+ // 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) {
+ ++Changes;
+ I->second = IDomValue;
+ DEBUG(dbgs() << " - BB#" << MBB->getNumber()
+ << " idom valno #" << IDomValue.first->id
+ << " from BB#" << IDom->getBlock()->getNumber() << '\n');
+ }
+ }
+ }
+ 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);
+ if (MBB == IdxMBB) {
+ li_->addRange(LiveRange(Start, Idx.getNextSlot(), IdxVNI));
+ continue;
+ }
+ // Anything in LiveIn other than IdxMBB is live-through.
+ VNInfo *VNI = liveOutCache_.lookup(MBB).first;
+ assert(VNI && "Missing block value");
+ li_->addRange(LiveRange(Start, lis_.getMBBEndIdx(MBB), VNI));
+ }
+
+ return IdxVNI;
+}
+
+// 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);
+}
+
+VNInfo *LiveIntervalMap::defByCopy(const VNInfo *ParentVNI,
+ MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator I) {
+ const TargetInstrDesc &TID = MBB.getParent()->getTarget().getInstrInfo()->
+ get(TargetOpcode::COPY);
+ MachineInstr *MI = BuildMI(MBB, I, DebugLoc(), TID, li_->reg)
+ .addReg(parentli_.reg);
+ SlotIndex DefIdx = lis_.InsertMachineInstrInMaps(MI).getDefIndex();
+ VNInfo *VNI = defValue(ParentVNI, DefIdx);
+ VNI->setCopy(MI);
+ li_->addRange(LiveRange(DefIdx, DefIdx.getNextSlot(), VNI));
+ return VNI;
+}
+
+//===----------------------------------------------------------------------===//
+// Split Editor
//===----------------------------------------------------------------------===//
-bool llvm::splitAroundLoop(SplitAnalysis &sa, const MachineLoop *loop) {
+/// 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()),
+ tii_(*vrm.getMachineFunction().getTarget().getInstrInfo()),
+ edit_(edit),
+ dupli_(lis_, mdt, edit.getParent()),
+ openli_(lis_, mdt, edit.getParent())
+{
+}
+
+bool SplitEditor::intervalsLiveAt(SlotIndex Idx) const {
+ for (LiveRangeEdit::iterator I = edit_.begin(), E = edit_.end(); I != E; ++I)
+ if (*I != dupli_.getLI() && (*I)->liveAt(Idx))
+ return true;
return false;
}
+/// Create a new virtual register and live interval.
+void SplitEditor::openIntv() {
+ assert(!openli_.getLI() && "Previous LI not closed before openIntv");
+
+ if (!dupli_.getLI())
+ dupli_.reset(&edit_.create(mri_, lis_, vrm_));
+
+ openli_.reset(&edit_.create(mri_, lis_, vrm_));
+}
+
+/// enterIntvBefore - Enter openli before the instruction at Idx. If curli is
+/// not live before Idx, a COPY is not inserted.
+void SplitEditor::enterIntvBefore(SlotIndex Idx) {
+ assert(openli_.getLI() && "openIntv not called before enterIntvBefore");
+ DEBUG(dbgs() << " enterIntvBefore " << Idx);
+ VNInfo *ParentVNI = edit_.getParent().getVNInfoAt(Idx.getUseIndex());
+ if (!ParentVNI) {
+ DEBUG(dbgs() << ": not live\n");
+ return;
+ }
+ DEBUG(dbgs() << ": valno " << ParentVNI->id);
+ truncatedValues.insert(ParentVNI);
+ MachineInstr *MI = lis_.getInstructionFromIndex(Idx);
+ assert(MI && "enterIntvBefore called with invalid index");
+ VNInfo *VNI = openli_.defByCopy(ParentVNI, *MI->getParent(), MI);
+ openli_.getLI()->addRange(LiveRange(VNI->def, Idx.getDefIndex(), VNI));
+ DEBUG(dbgs() << ": " << *openli_.getLI() << '\n');
+}
+
+/// enterIntvAtEnd - Enter openli at the end of MBB.
+void SplitEditor::enterIntvAtEnd(MachineBasicBlock &MBB) {
+ assert(openli_.getLI() && "openIntv not called before enterIntvAtEnd");
+ SlotIndex End = lis_.getMBBEndIdx(&MBB);
+ DEBUG(dbgs() << " enterIntvAtEnd BB#" << MBB.getNumber() << ", " << End);
+ VNInfo *ParentVNI = edit_.getParent().getVNInfoAt(End.getPrevSlot());
+ if (!ParentVNI) {
+ DEBUG(dbgs() << ": not live\n");
+ return;
+ }
+ DEBUG(dbgs() << ": valno " << ParentVNI->id);
+ truncatedValues.insert(ParentVNI);
+ VNInfo *VNI = openli_.defByCopy(ParentVNI, MBB, MBB.getFirstTerminator());
+ // Make sure openli is live out of MBB.
+ openli_.getLI()->addRange(LiveRange(VNI->def, End, VNI));
+ DEBUG(dbgs() << ": " << *openli_.getLI() << '\n');
+}
+
+/// useIntv - indicate that all instructions in MBB should use openli.
+void SplitEditor::useIntv(const MachineBasicBlock &MBB) {
+ useIntv(lis_.getMBBStartIdx(&MBB), lis_.getMBBEndIdx(&MBB));
+}
+
+void SplitEditor::useIntv(SlotIndex Start, SlotIndex End) {
+ assert(openli_.getLI() && "openIntv not called before useIntv");
+ openli_.addRange(Start, End);
+ DEBUG(dbgs() << " use [" << Start << ';' << End << "): "
+ << *openli_.getLI() << '\n');
+}
+
+/// leaveIntvAfter - Leave openli after the instruction at Idx.
+void SplitEditor::leaveIntvAfter(SlotIndex Idx) {
+ assert(openli_.getLI() && "openIntv not called before leaveIntvAfter");
+ DEBUG(dbgs() << " leaveIntvAfter " << Idx);
+
+ // The interval must be live beyond the instruction at Idx.
+ VNInfo *ParentVNI = edit_.getParent().getVNInfoAt(Idx.getBoundaryIndex());
+ if (!ParentVNI) {
+ DEBUG(dbgs() << ": not live\n");
+ return;
+ }
+ DEBUG(dbgs() << ": valno " << ParentVNI->id);
+
+ MachineBasicBlock::iterator MII = lis_.getInstructionFromIndex(Idx);
+ MachineBasicBlock *MBB = MII->getParent();
+ VNInfo *VNI = dupli_.defByCopy(ParentVNI, *MBB, llvm::next(MII));
+
+ // Finally we must make sure that openli is properly extended from Idx to the
+ // new copy.
+ openli_.addSimpleRange(Idx.getBoundaryIndex(), VNI->def, ParentVNI);
+ DEBUG(dbgs() << ": " << *openli_.getLI() << '\n');
+}
+
+/// leaveIntvAtTop - Leave the interval at the top of MBB.
+/// Currently, only one value can leave the interval.
+void SplitEditor::leaveIntvAtTop(MachineBasicBlock &MBB) {
+ assert(openli_.getLI() && "openIntv not called before leaveIntvAtTop");
+ SlotIndex Start = lis_.getMBBStartIdx(&MBB);
+ DEBUG(dbgs() << " leaveIntvAtTop BB#" << MBB.getNumber() << ", " << Start);
+
+ VNInfo *ParentVNI = edit_.getParent().getVNInfoAt(Start);
+ if (!ParentVNI) {
+ DEBUG(dbgs() << ": not live\n");
+ return;
+ }
+
+ // We are going to insert a back copy, so we must have a dupli_.
+ VNInfo *VNI = dupli_.defByCopy(ParentVNI, MBB,
+ MBB.SkipPHIsAndLabels(MBB.begin()));
+
+ // Finally we must make sure that openli is properly extended from Start to
+ // the new copy.
+ openli_.addSimpleRange(Start, VNI->def, ParentVNI);
+ DEBUG(dbgs() << ": " << *openli_.getLI() << '\n');
+}
+
+/// closeIntv - Indicate that we are done editing the currently open
+/// LiveInterval, and ranges can be trimmed.
+void SplitEditor::closeIntv() {
+ assert(openli_.getLI() && "openIntv not called before closeIntv");
+
+ DEBUG(dbgs() << " closeIntv cleaning up\n");
+ DEBUG(dbgs() << " open " << *openli_.getLI() << '\n');
+ openli_.reset(0);
+}
+
+/// rewrite - Rewrite all uses of reg to use the new registers.
+void SplitEditor::rewrite(unsigned reg) {
+ for (MachineRegisterInfo::reg_iterator RI = mri_.reg_begin(reg),
+ RE = mri_.reg_end(); RI != RE;) {
+ MachineOperand &MO = RI.getOperand();
+ unsigned OpNum = RI.getOperandNo();
+ MachineInstr *MI = MO.getParent();
+ ++RI;
+ if (MI->isDebugValue()) {
+ DEBUG(dbgs() << "Zapping " << *MI);
+ // FIXME: We can do much better with debug values.
+ MO.setReg(0);
+ continue;
+ }
+ SlotIndex Idx = lis_.getInstructionIndex(MI);
+ Idx = MO.isUse() ? Idx.getUseIndex() : Idx.getDefIndex();
+ LiveInterval *LI = 0;
+ for (LiveRangeEdit::iterator I = edit_.begin(), E = edit_.end(); I != E;
+ ++I) {
+ LiveInterval *testli = *I;
+ if (testli->liveAt(Idx)) {
+ LI = testli;
+ break;
+ }
+ }
+ DEBUG(dbgs() << " rewr BB#" << MI->getParent()->getNumber() << '\t'<< Idx);
+ assert(LI && "No register was live at use");
+ MO.setReg(LI->reg);
+ if (MO.isUse() && !MI->isRegTiedToDefOperand(OpNum))
+ MO.setIsKill(LI->killedAt(Idx.getDefIndex()));
+ DEBUG(dbgs() << '\t' << *MI);
+ }
+}
+
+void
+SplitEditor::addTruncSimpleRange(SlotIndex Start, SlotIndex End, VNInfo *VNI) {
+ // Build vector of iterator pairs from the intervals.
+ typedef std::pair<LiveInterval::const_iterator,
+ LiveInterval::const_iterator> IIPair;
+ SmallVector<IIPair, 8> Iters;
+ for (LiveRangeEdit::iterator LI = edit_.begin(), LE = edit_.end(); LI != LE;
+ ++LI) {
+ if (*LI == dupli_.getLI())
+ continue;
+ LiveInterval::const_iterator I = (*LI)->find(Start);
+ LiveInterval::const_iterator E = (*LI)->end();
+ if (I != E)
+ Iters.push_back(std::make_pair(I, E));
+ }
+
+ SlotIndex sidx = Start;
+ // Break [Start;End) into segments that don't overlap any intervals.
+ for (;;) {
+ SlotIndex next = sidx, eidx = End;
+ // Find overlapping intervals.
+ for (unsigned i = 0; i != Iters.size() && sidx < eidx; ++i) {
+ LiveInterval::const_iterator I = Iters[i].first;
+ // Interval I is overlapping [sidx;eidx). Trim sidx.
+ if (I->start <= sidx) {
+ sidx = I->end;
+ // Move to the next run, remove iters when all are consumed.
+ I = ++Iters[i].first;
+ if (I == Iters[i].second) {
+ Iters.erase(Iters.begin() + i);
+ --i;
+ continue;
+ }
+ }
+ // Trim eidx too if needed.
+ if (I->start >= eidx)
+ continue;
+ eidx = I->start;
+ next = I->end;
+ }
+ // Now, [sidx;eidx) doesn't overlap anything in intervals_.
+ if (sidx < eidx)
+ dupli_.addSimpleRange(sidx, eidx, VNI);
+ // If the interval end was truncated, we can try again from next.
+ if (next <= sidx)
+ break;
+ sidx = next;
+ }
+}
+
+void SplitEditor::computeRemainder() {
+ // First we need to fill in the live ranges in dupli.
+ // If values were redefined, we need a full recoloring with SSA update.
+ // If values were truncated, we only need to truncate the ranges.
+ // If values were partially rematted, we should shrink to uses.
+ // If values were fully rematted, they should be omitted.
+ // FIXME: If a single value is redefined, just move the def and truncate.
+ LiveInterval &parent = edit_.getParent();
+
+ // Values that are fully contained in the split intervals.
+ SmallPtrSet<const VNInfo*, 8> deadValues;
+ // Map all curli values that should have live defs in dupli.
+ for (LiveInterval::const_vni_iterator I = parent.vni_begin(),
+ E = parent.vni_end(); I != E; ++I) {
+ const VNInfo *VNI = *I;
+ // Don't transfer unused values to the new intervals.
+ if (VNI->isUnused())
+ continue;
+ // Original def is contained in the split intervals.
+ if (intervalsLiveAt(VNI->def)) {
+ // Did this value escape?
+ if (dupli_.isMapped(VNI))
+ truncatedValues.insert(VNI);
+ else
+ deadValues.insert(VNI);
+ continue;
+ }
+ // Add minimal live range at the definition.
+ VNInfo *DVNI = dupli_.defValue(VNI, VNI->def);
+ dupli_.getLI()->addRange(LiveRange(VNI->def, VNI->def.getNextSlot(), DVNI));
+ }
+
+ // Add all ranges to dupli.
+ for (LiveInterval::const_iterator I = parent.begin(), E = parent.end();
+ I != E; ++I) {
+ const LiveRange &LR = *I;
+ if (truncatedValues.count(LR.valno)) {
+ // recolor after removing intervals_.
+ addTruncSimpleRange(LR.start, LR.end, LR.valno);
+ } else if (!deadValues.count(LR.valno)) {
+ // recolor without truncation.
+ dupli_.addSimpleRange(LR.start, LR.end, LR.valno);
+ }
+ }
+
+ // Extend dupli_ to be live out of any critical loop predecessors.
+ // This means we have multiple registers live out of those blocks.
+ // The alternative would be to split the critical edges.
+ if (criticalPreds_.empty())
+ return;
+ for (SplitAnalysis::BlockPtrSet::iterator I = criticalPreds_.begin(),
+ E = criticalPreds_.end(); I != E; ++I)
+ dupli_.extendTo(*I, lis_.getMBBEndIdx(*I).getPrevSlot());
+ criticalPreds_.clear();
+}
+
+void SplitEditor::finish() {
+ assert(!openli_.getLI() && "Previous LI not closed before rewrite");
+ assert(dupli_.getLI() && "No dupli for rewrite. Noop spilt?");
+
+ // Complete dupli liveness.
+ computeRemainder();
+
+ // Get rid of unused values and set phi-kill flags.
+ for (LiveRangeEdit::iterator I = edit_.begin(), E = edit_.end(); I != E; ++I)
+ (*I)->RenumberValues(lis_);
+
+ // Rewrite instructions.
+ rewrite(edit_.getReg());
+
+ // Now check if any registers were separated into multiple components.
+ ConnectedVNInfoEqClasses ConEQ(lis_);
+ 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);
+ unsigned NumComp = ConEQ.Classify(li);
+ if (NumComp <= 1)
+ continue;
+ DEBUG(dbgs() << " " << NumComp << " components: " << *li << '\n');
+ SmallVector<LiveInterval*, 8> dups;
+ dups.push_back(li);
+ for (unsigned i = 1; i != NumComp; ++i)
+ dups.push_back(&edit_.create(mri_, lis_, vrm_));
+ ConEQ.Distribute(&dups[0]);
+ // Rewrite uses to the new regs.
+ rewrite(li->reg);
+ }
+
+ // 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){
+ LiveInterval &li = **I;
+ vrai.CalculateRegClass(li.reg);
+ vrai.CalculateWeightAndHint(li);
+ DEBUG(dbgs() << " new interval " << mri_.getRegClass(li.reg)->getName()
+ << ":" << li << '\n');
+ }
+}
+
+
+//===----------------------------------------------------------------------===//
+// 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");
+
+ // Get critical predecessors so computeRemainder can deal with them.
+ sa_.getCriticalPreds(Blocks, criticalPreds_);
+
+ // Create new live interval for the loop.
+ openIntv();
+
+ // Insert copies in the predecessors.
+ 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
+//===----------------------------------------------------------------------===//
+
+/// getMultiUseBlocks - if curli has more than one use in a basic block, it
+/// 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)
+ 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:
+ 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);
+ }
+ return !Blocks.empty();
+}
+
+/// splitSingleBlocks - Split curli into a separate live interval inside each
+/// 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();
+ enterIntvBefore(IP.first);
+ useIntv(IP.first.getBaseIndex(), IP.second.getBoundaryIndex());
+ 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();
+ enterIntvBefore(Uses.front());
+ useIntv(Uses.front().getBaseIndex(), Uses[bestPos-1].getBoundaryIndex());
+ leaveIntvAfter(Uses[bestPos-1]);
+ closeIntv();
+ }
+
+ // Second interval after the gap.
+ if (bestPos < Uses.size()-1) {
+ openIntv();
+ enterIntvBefore(Uses[bestPos]);
+ useIntv(Uses[bestPos].getBaseIndex(), Uses.back().getBoundaryIndex());
+ leaveIntvAfter(Uses.back());
+ closeIntv();
+ }
+
+ finish();
+}
projects / oota-llvm.git / blobdiff