-//===-- LiveIntervals.cpp - Live Interval Analysis ------------------------===//
+//===-- LiveIntervalAnalysis.cpp - Live Interval Analysis -----------------===//
//
// The LLVM Compiler Infrastructure
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "liveintervals"
-#include "LiveIntervals.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "VirtRegMap.h"
#include "llvm/Value.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/CodeGen/LiveVariables.h"
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
-#include "Support/CommandLine.h"
-#include "Support/Debug.h"
-#include "Support/Statistic.h"
-#include "Support/STLExtras.h"
-#include "VirtRegMap.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include <algorithm>
#include <cmath>
-#include <iostream>
-
using namespace llvm;
+STATISTIC(numIntervals, "Number of original intervals");
+STATISTIC(numIntervalsAfter, "Number of intervals after coalescing");
+STATISTIC(numJoins , "Number of interval joins performed");
+STATISTIC(numPeep , "Number of identity moves eliminated after coalescing");
+STATISTIC(numFolded , "Number of loads/stores folded into instructions");
+STATISTIC(numAborts , "Number of times interval joining aborted");
+
namespace {
- RegisterAnalysis<LiveIntervals> X("liveintervals",
- "Live Interval Analysis");
-
- Statistic<> numIntervals
- ("liveintervals", "Number of original intervals");
-
- Statistic<> numIntervalsAfter
- ("liveintervals", "Number of intervals after coalescing");
-
- Statistic<> numJoins
- ("liveintervals", "Number of interval joins performed");
-
- Statistic<> numPeep
- ("liveintervals", "Number of identity moves eliminated after coalescing");
-
- Statistic<> numFolded
- ("liveintervals", "Number of loads/stores folded into instructions");
-
- cl::opt<bool>
- EnableJoining("join-liveintervals",
- cl::desc("Join compatible live intervals"),
- cl::init(true));
-};
-
-void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const
-{
- AU.addPreserved<LiveVariables>();
- AU.addRequired<LiveVariables>();
- AU.addPreservedID(PHIEliminationID);
- AU.addRequiredID(PHIEliminationID);
- AU.addRequiredID(TwoAddressInstructionPassID);
- AU.addRequired<LoopInfo>();
- MachineFunctionPass::getAnalysisUsage(AU);
+ RegisterPass<LiveIntervals> X("liveintervals", "Live Interval Analysis");
+
+ static cl::opt<bool>
+ EnableJoining("join-liveintervals",
+ cl::desc("Coallesce copies (default=true)"),
+ cl::init(true));
+}
+
+void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<LiveVariables>();
+ AU.addPreservedID(PHIEliminationID);
+ AU.addRequiredID(PHIEliminationID);
+ AU.addRequiredID(TwoAddressInstructionPassID);
+ AU.addRequired<LoopInfo>();
+ MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+void LiveIntervals::releaseMemory() {
+ mi2iMap_.clear();
+ i2miMap_.clear();
+ r2iMap_.clear();
+ r2rMap_.clear();
+ JoinedLIs.clear();
}
-void LiveIntervals::releaseMemory()
-{
- mi2iMap_.clear();
- i2miMap_.clear();
- r2iMap_.clear();
- r2rMap_.clear();
- intervals_.clear();
+
+static bool isZeroLengthInterval(LiveInterval *li) {
+ for (LiveInterval::Ranges::const_iterator
+ i = li->ranges.begin(), e = li->ranges.end(); i != e; ++i)
+ if (i->end - i->start > LiveIntervals::InstrSlots::NUM)
+ return false;
+ return true;
}
/// runOnMachineFunction - Register allocate the whole function
///
bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
- mf_ = &fn;
- tm_ = &fn.getTarget();
- mri_ = tm_->getRegisterInfo();
- lv_ = &getAnalysis<LiveVariables>();
-
- // number MachineInstrs
- unsigned miIndex = 0;
- for (MachineFunction::iterator mbb = mf_->begin(), mbbEnd = mf_->end();
- mbb != mbbEnd; ++mbb)
- for (MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
- mi != miEnd; ++mi) {
- bool inserted = mi2iMap_.insert(std::make_pair(mi, miIndex)).second;
- assert(inserted && "multiple MachineInstr -> index mappings");
- i2miMap_.push_back(mi);
- miIndex += InstrSlots::NUM;
+ mf_ = &fn;
+ tm_ = &fn.getTarget();
+ mri_ = tm_->getRegisterInfo();
+ tii_ = tm_->getInstrInfo();
+ lv_ = &getAnalysis<LiveVariables>();
+ allocatableRegs_ = mri_->getAllocatableSet(fn);
+ r2rMap_.grow(mf_->getSSARegMap()->getLastVirtReg());
+
+ // Number MachineInstrs and MachineBasicBlocks.
+ // Initialize MBB indexes to a sentinal.
+ MBB2IdxMap.resize(mf_->getNumBlockIDs(), ~0U);
+
+ unsigned MIIndex = 0;
+ for (MachineFunction::iterator MBB = mf_->begin(), E = mf_->end();
+ MBB != E; ++MBB) {
+ // Set the MBB2IdxMap entry for this MBB.
+ MBB2IdxMap[MBB->getNumber()] = MIIndex;
+
+ for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
+ I != E; ++I) {
+ bool inserted = mi2iMap_.insert(std::make_pair(I, MIIndex)).second;
+ assert(inserted && "multiple MachineInstr -> index mappings");
+ i2miMap_.push_back(I);
+ MIIndex += InstrSlots::NUM;
+ }
+ }
+
+ computeIntervals();
+
+ numIntervals += getNumIntervals();
+
+ DOUT << "********** INTERVALS **********\n";
+ for (iterator I = begin(), E = end(); I != E; ++I) {
+ I->second.print(DOUT, mri_);
+ DOUT << "\n";
+ }
+
+ // Join (coallesce) intervals if requested.
+ if (EnableJoining) joinIntervals();
+
+ numIntervalsAfter += getNumIntervals();
+
+
+ // perform a final pass over the instructions and compute spill
+ // weights, coalesce virtual registers and remove identity moves.
+ const LoopInfo &loopInfo = getAnalysis<LoopInfo>();
+
+ for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
+ mbbi != mbbe; ++mbbi) {
+ MachineBasicBlock* mbb = mbbi;
+ unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock());
+
+ for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end();
+ mii != mie; ) {
+ // if the move will be an identity move delete it
+ unsigned srcReg, dstReg, RegRep;
+ if (tii_->isMoveInstr(*mii, srcReg, dstReg) &&
+ (RegRep = rep(srcReg)) == rep(dstReg)) {
+ // remove from def list
+ LiveInterval &RegInt = getOrCreateInterval(RegRep);
+ MachineOperand *MO = mii->findRegisterDefOperand(dstReg);
+ // If def of this move instruction is dead, remove its live range from
+ // the dstination register's live interval.
+ if (MO->isDead()) {
+ unsigned MoveIdx = getDefIndex(getInstructionIndex(mii));
+ LiveInterval::iterator MLR = RegInt.FindLiveRangeContaining(MoveIdx);
+ RegInt.removeRange(MLR->start, MoveIdx+1);
+ if (RegInt.empty())
+ removeInterval(RegRep);
}
-
- computeIntervals();
-
- numIntervals += intervals_.size();
-
- // join intervals if requested
- if (EnableJoining) joinIntervals();
- //DEBUG(mf_->viewCFG());
-
- numIntervalsAfter += intervals_.size();
-
- // perform a final pass over the instructions and compute spill
- // weights, coalesce virtual registers and remove identity moves
- const LoopInfo& loopInfo = getAnalysis<LoopInfo>();
- const TargetInstrInfo& tii = *tm_->getInstrInfo();
-
- for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
- mbbi != mbbe; ++mbbi) {
- MachineBasicBlock* mbb = mbbi;
- unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock());
-
- for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end();
- mii != mie; ) {
- // if the move will be an identity move delete it
- unsigned srcReg, dstReg;
- if (tii.isMoveInstr(*mii, srcReg, dstReg) &&
- rep(srcReg) == rep(dstReg)) {
- // remove from def list
- LiveInterval& interval = getOrCreateInterval(rep(dstReg));
- // remove index -> MachineInstr and
- // MachineInstr -> index mappings
- Mi2IndexMap::iterator mi2i = mi2iMap_.find(mii);
- if (mi2i != mi2iMap_.end()) {
- i2miMap_[mi2i->second/InstrSlots::NUM] = 0;
- mi2iMap_.erase(mi2i);
- }
- mii = mbbi->erase(mii);
- ++numPeep;
- }
- else {
- for (unsigned i = 0; i < mii->getNumOperands(); ++i) {
- const MachineOperand& mop = mii->getOperand(i);
- if (mop.isRegister() && mop.getReg() &&
- MRegisterInfo::isVirtualRegister(mop.getReg())) {
- // replace register with representative register
- unsigned reg = rep(mop.getReg());
- mii->SetMachineOperandReg(i, reg);
-
- Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
- assert(r2iit != r2iMap_.end());
- r2iit->second->weight +=
- (mop.isUse() + mop.isDef()) * pow(10.0F, loopDepth);
- }
- }
- ++mii;
- }
+ RemoveMachineInstrFromMaps(mii);
+ mii = mbbi->erase(mii);
+ ++numPeep;
+ } else {
+ for (unsigned i = 0, e = mii->getNumOperands(); i != e; ++i) {
+ const MachineOperand &mop = mii->getOperand(i);
+ if (mop.isRegister() && mop.getReg() &&
+ MRegisterInfo::isVirtualRegister(mop.getReg())) {
+ // replace register with representative register
+ unsigned reg = rep(mop.getReg());
+ mii->getOperand(i).setReg(reg);
+
+ LiveInterval &RegInt = getInterval(reg);
+ float w = (mop.isUse()+mop.isDef()) * powf(10.0F, (float)loopDepth);
+ // If the definition instruction is re-materializable, its spill
+ // weight is half of what it would have been normally unless it's
+ // a load from fixed stack slot.
+ int Dummy;
+ if (RegInt.remat && !tii_->isLoadFromStackSlot(RegInt.remat, Dummy))
+ w /= 2;
+ RegInt.weight += w;
+ }
}
+ ++mii;
+ }
+ }
+ }
+
+ for (iterator I = begin(), E = end(); I != E; ++I) {
+ LiveInterval &LI = I->second;
+ if (MRegisterInfo::isVirtualRegister(LI.reg)) {
+ // If the live interval length is essentially zero, i.e. in every live
+ // range the use follows def immediately, it doesn't make sense to spill
+ // it and hope it will be easier to allocate for this li.
+ if (isZeroLengthInterval(&LI))
+ LI.weight = HUGE_VALF;
+
+ // Divide the weight of the interval by its size. This encourages
+ // spilling of intervals that are large and have few uses, and
+ // discourages spilling of small intervals with many uses.
+ unsigned Size = 0;
+ for (LiveInterval::iterator II = LI.begin(), E = LI.end(); II != E;++II)
+ Size += II->end - II->start;
+
+ LI.weight /= Size;
}
+ }
- intervals_.sort();
- DEBUG(std::cerr << "********** INTERVALS **********\n");
- DEBUG(std::copy(intervals_.begin(), intervals_.end(),
- std::ostream_iterator<LiveInterval>(std::cerr, "\n")));
- DEBUG(std::cerr << "********** MACHINEINSTRS **********\n");
- DEBUG(
- for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
- mbbi != mbbe; ++mbbi) {
- std::cerr << ((Value*)mbbi->getBasicBlock())->getName() << ":\n";
- for (MachineBasicBlock::iterator mii = mbbi->begin(),
- mie = mbbi->end(); mii != mie; ++mii) {
- std::cerr << getInstructionIndex(mii) << '\t';
- mii->print(std::cerr, tm_);
- }
- });
+ DEBUG(dump());
+ return true;
+}
- return true;
+/// print - Implement the dump method.
+void LiveIntervals::print(std::ostream &O, const Module* ) const {
+ O << "********** INTERVALS **********\n";
+ for (const_iterator I = begin(), E = end(); I != E; ++I) {
+ I->second.print(DOUT, mri_);
+ DOUT << "\n";
+ }
+
+ O << "********** MACHINEINSTRS **********\n";
+ for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
+ mbbi != mbbe; ++mbbi) {
+ O << ((Value*)mbbi->getBasicBlock())->getName() << ":\n";
+ for (MachineBasicBlock::iterator mii = mbbi->begin(),
+ mie = mbbi->end(); mii != mie; ++mii) {
+ O << getInstructionIndex(mii) << '\t' << *mii;
+ }
+ }
}
-namespace {
- /// CompareIntervalStar - This is a simple comparison function for interval
- /// pointers. It compares based on their starting point.
- struct CompareIntervalStar {
- bool operator()(LiveInterval *LHS, LiveInterval* RHS) const {
- return LHS->start() < RHS->start();
- }
- };
+/// CreateNewLiveInterval - Create a new live interval with the given live
+/// ranges. The new live interval will have an infinite spill weight.
+LiveInterval&
+LiveIntervals::CreateNewLiveInterval(const LiveInterval *LI,
+ const std::vector<LiveRange> &LRs) {
+ const TargetRegisterClass *RC = mf_->getSSARegMap()->getRegClass(LI->reg);
+
+ // Create a new virtual register for the spill interval.
+ unsigned NewVReg = mf_->getSSARegMap()->createVirtualRegister(RC);
+
+ // Replace the old virtual registers in the machine operands with the shiny
+ // new one.
+ for (std::vector<LiveRange>::const_iterator
+ I = LRs.begin(), E = LRs.end(); I != E; ++I) {
+ unsigned Index = getBaseIndex(I->start);
+ unsigned End = getBaseIndex(I->end - 1) + InstrSlots::NUM;
+
+ for (; Index != End; Index += InstrSlots::NUM) {
+ // Skip deleted instructions
+ while (Index != End && !getInstructionFromIndex(Index))
+ Index += InstrSlots::NUM;
+
+ if (Index == End) break;
+
+ MachineInstr *MI = getInstructionFromIndex(Index);
+
+ for (unsigned J = 0, e = MI->getNumOperands(); J != e; ++J) {
+ MachineOperand &MOp = MI->getOperand(J);
+ if (MOp.isRegister() && rep(MOp.getReg()) == LI->reg)
+ MOp.setReg(NewVReg);
+ }
+ }
+ }
+
+ LiveInterval &NewLI = getOrCreateInterval(NewVReg);
+
+ // The spill weight is now infinity as it cannot be spilled again
+ NewLI.weight = float(HUGE_VAL);
+
+ for (std::vector<LiveRange>::const_iterator
+ I = LRs.begin(), E = LRs.end(); I != E; ++I) {
+ DOUT << " Adding live range " << *I << " to new interval\n";
+ NewLI.addRange(*I);
+ }
+
+ DOUT << "Created new live interval " << NewLI << "\n";
+ return NewLI;
}
-std::vector<LiveInterval*> LiveIntervals::addIntervalsForSpills(
- const LiveInterval& li,
- VirtRegMap& vrm,
- int slot)
-{
- std::vector<LiveInterval*> added;
-
- assert(li.weight != HUGE_VAL &&
- "attempt to spill already spilled interval!");
-
- DEBUG(std::cerr << "\t\t\t\tadding intervals for spills for interval: "
- << li << '\n');
-
- const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(li.reg);
-
- for (LiveInterval::Ranges::const_iterator
- i = li.ranges.begin(), e = li.ranges.end(); i != e; ++i) {
- unsigned index = getBaseIndex(i->first);
- unsigned end = getBaseIndex(i->second-1) + InstrSlots::NUM;
- for (; index < end; index += InstrSlots::NUM) {
- // skip deleted instructions
- while (!getInstructionFromIndex(index)) index += InstrSlots::NUM;
- MachineBasicBlock::iterator mi = getInstructionFromIndex(index);
-
- for_operand:
- for (unsigned i = 0; i != mi->getNumOperands(); ++i) {
- MachineOperand& mop = mi->getOperand(i);
- if (mop.isRegister() && mop.getReg() == li.reg) {
- if (MachineInstr* fmi =
- mri_->foldMemoryOperand(mi, i, slot)) {
- lv_->instructionChanged(mi, fmi);
- vrm.virtFolded(li.reg, mi, fmi);
- mi2iMap_.erase(mi);
- i2miMap_[index/InstrSlots::NUM] = fmi;
- mi2iMap_[fmi] = index;
- MachineBasicBlock& mbb = *mi->getParent();
- mi = mbb.insert(mbb.erase(mi), fmi);
- ++numFolded;
- goto for_operand;
- }
- else {
- // This is tricky. We need to add information in
- // the interval about the spill code so we have to
- // use our extra load/store slots.
- //
- // If we have a use we are going to have a load so
- // we start the interval from the load slot
- // onwards. Otherwise we start from the def slot.
- unsigned start = (mop.isUse() ?
- getLoadIndex(index) :
- getDefIndex(index));
- // If we have a def we are going to have a store
- // right after it so we end the interval after the
- // use of the next instruction. Otherwise we end
- // after the use of this instruction.
- unsigned end = 1 + (mop.isDef() ?
- getStoreIndex(index) :
- getUseIndex(index));
-
- // create a new register for this spill
- unsigned nReg =
- mf_->getSSARegMap()->createVirtualRegister(rc);
- mi->SetMachineOperandReg(i, nReg);
- vrm.grow();
- vrm.assignVirt2StackSlot(nReg, slot);
- LiveInterval& nI = getOrCreateInterval(nReg);
- assert(nI.empty());
- // the spill weight is now infinity as it
- // cannot be spilled again
- nI.weight = HUGE_VAL;
- nI.addRange(start, end);
- added.push_back(&nI);
- // update live variables
- lv_->addVirtualRegisterKilled(nReg, mi);
- DEBUG(std::cerr << "\t\t\t\tadded new interval: "
- << nI << '\n');
- }
- }
+std::vector<LiveInterval*> LiveIntervals::
+addIntervalsForSpills(const LiveInterval &li, VirtRegMap &vrm, int slot) {
+ // since this is called after the analysis is done we don't know if
+ // LiveVariables is available
+ lv_ = getAnalysisToUpdate<LiveVariables>();
+
+ std::vector<LiveInterval*> added;
+
+ assert(li.weight != HUGE_VALF &&
+ "attempt to spill already spilled interval!");
+
+ DOUT << "\t\t\t\tadding intervals for spills for interval: ";
+ li.print(DOUT, mri_);
+ DOUT << '\n';
+
+ const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(li.reg);
+
+ for (LiveInterval::Ranges::const_iterator
+ i = li.ranges.begin(), e = li.ranges.end(); i != e; ++i) {
+ unsigned index = getBaseIndex(i->start);
+ unsigned end = getBaseIndex(i->end-1) + InstrSlots::NUM;
+ for (; index != end; index += InstrSlots::NUM) {
+ // skip deleted instructions
+ while (index != end && !getInstructionFromIndex(index))
+ index += InstrSlots::NUM;
+ if (index == end) break;
+
+ MachineInstr *MI = getInstructionFromIndex(index);
+
+ RestartInstruction:
+ for (unsigned i = 0; i != MI->getNumOperands(); ++i) {
+ MachineOperand& mop = MI->getOperand(i);
+ if (mop.isRegister() && mop.getReg() == li.reg) {
+ MachineInstr *fmi = li.remat ? NULL
+ : mri_->foldMemoryOperand(MI, i, slot);
+ if (fmi) {
+ // Attempt to fold the memory reference into the instruction. If we
+ // can do this, we don't need to insert spill code.
+ if (lv_)
+ lv_->instructionChanged(MI, fmi);
+ MachineBasicBlock &MBB = *MI->getParent();
+ vrm.virtFolded(li.reg, MI, i, fmi);
+ mi2iMap_.erase(MI);
+ i2miMap_[index/InstrSlots::NUM] = fmi;
+ mi2iMap_[fmi] = index;
+ MI = MBB.insert(MBB.erase(MI), fmi);
+ ++numFolded;
+ // Folding the load/store can completely change the instruction in
+ // unpredictable ways, rescan it from the beginning.
+ goto RestartInstruction;
+ } else {
+ // Create a new virtual register for the spill interval.
+ unsigned NewVReg = mf_->getSSARegMap()->createVirtualRegister(rc);
+
+ // Scan all of the operands of this instruction rewriting operands
+ // to use NewVReg instead of li.reg as appropriate. We do this for
+ // two reasons:
+ //
+ // 1. If the instr reads the same spilled vreg multiple times, we
+ // want to reuse the NewVReg.
+ // 2. If the instr is a two-addr instruction, we are required to
+ // keep the src/dst regs pinned.
+ //
+ // Keep track of whether we replace a use and/or def so that we can
+ // create the spill interval with the appropriate range.
+ mop.setReg(NewVReg);
+
+ bool HasUse = mop.isUse();
+ bool HasDef = mop.isDef();
+ for (unsigned j = i+1, e = MI->getNumOperands(); j != e; ++j) {
+ if (MI->getOperand(j).isReg() &&
+ MI->getOperand(j).getReg() == li.reg) {
+ MI->getOperand(j).setReg(NewVReg);
+ HasUse |= MI->getOperand(j).isUse();
+ HasDef |= MI->getOperand(j).isDef();
+ }
+ }
+
+ // create a new register for this spill
+ vrm.grow();
+ if (li.remat)
+ vrm.setVirtIsReMaterialized(NewVReg, li.remat);
+ vrm.assignVirt2StackSlot(NewVReg, slot);
+ LiveInterval &nI = getOrCreateInterval(NewVReg);
+ nI.remat = li.remat;
+ assert(nI.empty());
+
+ // the spill weight is now infinity as it
+ // cannot be spilled again
+ nI.weight = HUGE_VALF;
+
+ if (HasUse) {
+ LiveRange LR(getLoadIndex(index), getUseIndex(index),
+ nI.getNextValue(~0U, 0));
+ DOUT << " +" << LR;
+ nI.addRange(LR);
+ }
+ if (HasDef) {
+ LiveRange LR(getDefIndex(index), getStoreIndex(index),
+ nI.getNextValue(~0U, 0));
+ DOUT << " +" << LR;
+ nI.addRange(LR);
}
+
+ added.push_back(&nI);
+
+ // update live variables if it is available
+ if (lv_)
+ lv_->addVirtualRegisterKilled(NewVReg, MI);
+
+ DOUT << "\t\t\t\tadded new interval: ";
+ nI.print(DOUT, mri_);
+ DOUT << '\n';
+ }
}
+ }
}
+ }
- // FIXME: This method MUST return intervals in sorted order. If a
- // particular machine instruction both uses and defines the vreg being
- // spilled (e.g., vr = vr + 1) and if the def is processed before the
- // use, the list ends up not sorted.
- //
- // The proper way to fix this is to process all uses of the vreg before we
- // process any defs. However, this would require refactoring the above
- // blob of code, which I'm not feeling up to right now.
- std::sort(added.begin(), added.end(), CompareIntervalStar());
- return added;
+ return added;
}
-void LiveIntervals::printRegName(unsigned reg) const
-{
- if (MRegisterInfo::isPhysicalRegister(reg))
- std::cerr << mri_->getName(reg);
- else
- std::cerr << "%reg" << reg;
+void LiveIntervals::printRegName(unsigned reg) const {
+ if (MRegisterInfo::isPhysicalRegister(reg))
+ cerr << mri_->getName(reg);
+ else
+ cerr << "%reg" << reg;
+}
+
+/// isReDefinedByTwoAddr - Returns true if the Reg re-definition is due to
+/// two addr elimination.
+static bool isReDefinedByTwoAddr(MachineInstr *MI, unsigned Reg,
+ const TargetInstrInfo *TII) {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO1 = MI->getOperand(i);
+ if (MO1.isRegister() && MO1.isDef() && MO1.getReg() == Reg) {
+ for (unsigned j = i+1; j < e; ++j) {
+ MachineOperand &MO2 = MI->getOperand(j);
+ if (MO2.isRegister() && MO2.isUse() && MO2.getReg() == Reg &&
+ MI->getInstrDescriptor()->
+ getOperandConstraint(j, TOI::TIED_TO) == (int)i)
+ return true;
+ }
+ }
+ }
+ return false;
}
-void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock* mbb,
+void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb,
MachineBasicBlock::iterator mi,
- LiveInterval& interval)
-{
- DEBUG(std::cerr << "\t\tregister: "; printRegName(interval.reg));
- LiveVariables::VarInfo& vi = lv_->getVarInfo(interval.reg);
-
- // Virtual registers may be defined multiple times (due to phi
- // elimination). Much of what we do only has to be done once for the vreg.
- // We use an empty interval to detect the first time we see a vreg.
- if (interval.empty()) {
-
- // Get the Idx of the defining instructions.
- unsigned defIndex = getDefIndex(getInstructionIndex(mi));
-
- // Loop over all of the blocks that the vreg is defined in. There are
- // two cases we have to handle here. The most common case is a vreg
- // whose lifetime is contained within a basic block. In this case there
- // will be a single kill, in MBB, which comes after the definition.
- if (vi.Kills.size() == 1 && vi.Kills[0].first == mbb) {
- // FIXME: what about dead vars?
- unsigned killIdx;
- if (vi.Kills[0].second != mi)
- killIdx = getUseIndex(getInstructionIndex(vi.Kills[0].second))+1;
- else
- killIdx = defIndex+1;
-
- // If the kill happens after the definition, we have an intra-block
- // live range.
- if (killIdx > defIndex) {
- assert(vi.AliveBlocks.empty() &&
- "Shouldn't be alive across any blocks!");
- interval.addRange(defIndex, killIdx);
- return;
- }
- }
-
- // The other case we handle is when a virtual register lives to the end
- // of the defining block, potentially live across some blocks, then is
- // live into some number of blocks, but gets killed. Start by adding a
- // range that goes from this definition to the end of the defining block.
- interval.addRange(defIndex,
- getInstructionIndex(&mbb->back()) + InstrSlots::NUM);
-
- // Iterate over all of the blocks that the variable is completely
- // live in, adding [insrtIndex(begin), instrIndex(end)+4) to the
- // live interval.
- for (unsigned i = 0, e = vi.AliveBlocks.size(); i != e; ++i) {
- if (vi.AliveBlocks[i]) {
- MachineBasicBlock* mbb = mf_->getBlockNumbered(i);
- if (!mbb->empty()) {
- interval.addRange(
- getInstructionIndex(&mbb->front()),
- getInstructionIndex(&mbb->back()) + InstrSlots::NUM);
- }
- }
- }
-
- // Finally, this virtual register is live from the start of any killing
- // block to the 'use' slot of the killing instruction.
- for (unsigned i = 0, e = vi.Kills.size(); i != e; ++i) {
- std::pair<MachineBasicBlock*, MachineInstr*> &Kill = vi.Kills[i];
- interval.addRange(getInstructionIndex(Kill.first->begin()),
- getUseIndex(getInstructionIndex(Kill.second))+1);
- }
+ unsigned MIIdx,
+ LiveInterval &interval) {
+ DOUT << "\t\tregister: "; DEBUG(printRegName(interval.reg));
+ LiveVariables::VarInfo& vi = lv_->getVarInfo(interval.reg);
+
+ // Virtual registers may be defined multiple times (due to phi
+ // elimination and 2-addr elimination). Much of what we do only has to be
+ // done once for the vreg. We use an empty interval to detect the first
+ // time we see a vreg.
+ if (interval.empty()) {
+ // Remember if the definition can be rematerialized. All load's from fixed
+ // stack slots are re-materializable.
+ int FrameIdx = 0;
+ if (vi.DefInst &&
+ (tii_->isReMaterializable(vi.DefInst->getOpcode()) ||
+ (tii_->isLoadFromStackSlot(vi.DefInst, FrameIdx) &&
+ mf_->getFrameInfo()->isFixedObjectIndex(FrameIdx))))
+ interval.remat = vi.DefInst;
+
+ // Get the Idx of the defining instructions.
+ unsigned defIndex = getDefIndex(MIIdx);
+
+ unsigned ValNum;
+ unsigned SrcReg, DstReg;
+ if (!tii_->isMoveInstr(*mi, SrcReg, DstReg))
+ ValNum = interval.getNextValue(~0U, 0);
+ else
+ ValNum = interval.getNextValue(defIndex, SrcReg);
+
+ assert(ValNum == 0 && "First value in interval is not 0?");
+ ValNum = 0; // Clue in the optimizer.
+
+ // Loop over all of the blocks that the vreg is defined in. There are
+ // two cases we have to handle here. The most common case is a vreg
+ // whose lifetime is contained within a basic block. In this case there
+ // will be a single kill, in MBB, which comes after the definition.
+ if (vi.Kills.size() == 1 && vi.Kills[0]->getParent() == mbb) {
+ // FIXME: what about dead vars?
+ unsigned killIdx;
+ if (vi.Kills[0] != mi)
+ killIdx = getUseIndex(getInstructionIndex(vi.Kills[0]))+1;
+ else
+ killIdx = defIndex+1;
+
+ // If the kill happens after the definition, we have an intra-block
+ // live range.
+ if (killIdx > defIndex) {
+ assert(vi.AliveBlocks.none() &&
+ "Shouldn't be alive across any blocks!");
+ LiveRange LR(defIndex, killIdx, ValNum);
+ interval.addRange(LR);
+ DOUT << " +" << LR << "\n";
+ return;
+ }
+ }
+
+ // The other case we handle is when a virtual register lives to the end
+ // of the defining block, potentially live across some blocks, then is
+ // live into some number of blocks, but gets killed. Start by adding a
+ // range that goes from this definition to the end of the defining block.
+ LiveRange NewLR(defIndex,
+ getInstructionIndex(&mbb->back()) + InstrSlots::NUM,
+ ValNum);
+ DOUT << " +" << NewLR;
+ interval.addRange(NewLR);
+
+ // Iterate over all of the blocks that the variable is completely
+ // live in, adding [insrtIndex(begin), instrIndex(end)+4) to the
+ // live interval.
+ for (unsigned i = 0, e = vi.AliveBlocks.size(); i != e; ++i) {
+ if (vi.AliveBlocks[i]) {
+ MachineBasicBlock *MBB = mf_->getBlockNumbered(i);
+ if (!MBB->empty()) {
+ LiveRange LR(getMBBStartIdx(i),
+ getInstructionIndex(&MBB->back()) + InstrSlots::NUM,
+ ValNum);
+ interval.addRange(LR);
+ DOUT << " +" << LR;
+ }
+ }
+ }
+
+ // Finally, this virtual register is live from the start of any killing
+ // block to the 'use' slot of the killing instruction.
+ for (unsigned i = 0, e = vi.Kills.size(); i != e; ++i) {
+ MachineInstr *Kill = vi.Kills[i];
+ LiveRange LR(getMBBStartIdx(Kill->getParent()),
+ getUseIndex(getInstructionIndex(Kill))+1,
+ ValNum);
+ interval.addRange(LR);
+ DOUT << " +" << LR;
+ }
+
+ } else {
+ // Can no longer safely assume definition is rematerializable.
+ interval.remat = NULL;
+
+ // If this is the second time we see a virtual register definition, it
+ // must be due to phi elimination or two addr elimination. If this is
+ // the result of two address elimination, then the vreg is one of the
+ // def-and-use register operand.
+ if (isReDefinedByTwoAddr(mi, interval.reg, tii_)) {
+ // If this is a two-address definition, then we have already processed
+ // the live range. The only problem is that we didn't realize there
+ // are actually two values in the live interval. Because of this we
+ // need to take the LiveRegion that defines this register and split it
+ // into two values.
+ unsigned DefIndex = getDefIndex(getInstructionIndex(vi.DefInst));
+ unsigned RedefIndex = getDefIndex(MIIdx);
+
+ // Delete the initial value, which should be short and continuous,
+ // because the 2-addr copy must be in the same MBB as the redef.
+ interval.removeRange(DefIndex, RedefIndex);
+
+ // Two-address vregs should always only be redefined once. This means
+ // that at this point, there should be exactly one value number in it.
+ assert(interval.containsOneValue() && "Unexpected 2-addr liveint!");
+
+ // The new value number (#1) is defined by the instruction we claimed
+ // defined value #0.
+ unsigned ValNo = interval.getNextValue(0, 0);
+ interval.setValueNumberInfo(1, interval.getValNumInfo(0));
+
+ // Value#0 is now defined by the 2-addr instruction.
+ interval.setValueNumberInfo(0, std::make_pair(~0U, 0U));
+
+ // Add the new live interval which replaces the range for the input copy.
+ LiveRange LR(DefIndex, RedefIndex, ValNo);
+ DOUT << " replace range with " << LR;
+ interval.addRange(LR);
+
+ // If this redefinition is dead, we need to add a dummy unit live
+ // range covering the def slot.
+ if (lv_->RegisterDefIsDead(mi, interval.reg))
+ interval.addRange(LiveRange(RedefIndex, RedefIndex+1, 0));
+
+ DOUT << " RESULT: ";
+ interval.print(DOUT, mri_);
} else {
- // If this is the second time we see a virtual register definition, it
- // must be due to phi elimination. In this case, the defined value will
- // be live until the end of the basic block it is defined in.
- unsigned defIndex = getDefIndex(getInstructionIndex(mi));
- interval.addRange(defIndex,
- getInstructionIndex(&mbb->back()) + InstrSlots::NUM);
+ // Otherwise, this must be because of phi elimination. If this is the
+ // first redefinition of the vreg that we have seen, go back and change
+ // the live range in the PHI block to be a different value number.
+ if (interval.containsOneValue()) {
+ assert(vi.Kills.size() == 1 &&
+ "PHI elimination vreg should have one kill, the PHI itself!");
+
+ // Remove the old range that we now know has an incorrect number.
+ MachineInstr *Killer = vi.Kills[0];
+ unsigned Start = getMBBStartIdx(Killer->getParent());
+ unsigned End = getUseIndex(getInstructionIndex(Killer))+1;
+ DOUT << " Removing [" << Start << "," << End << "] from: ";
+ interval.print(DOUT, mri_); DOUT << "\n";
+ interval.removeRange(Start, End);
+ DOUT << " RESULT: "; interval.print(DOUT, mri_);
+
+ // Replace the interval with one of a NEW value number. Note that this
+ // value number isn't actually defined by an instruction, weird huh? :)
+ LiveRange LR(Start, End, interval.getNextValue(~0U, 0));
+ DOUT << " replace range with " << LR;
+ interval.addRange(LR);
+ DOUT << " RESULT: "; interval.print(DOUT, mri_);
+ }
+
+ // In the case of PHI elimination, each variable definition is only
+ // live until the end of the block. We've already taken care of the
+ // rest of the live range.
+ unsigned defIndex = getDefIndex(MIIdx);
+
+ unsigned ValNum;
+ unsigned SrcReg, DstReg;
+ if (!tii_->isMoveInstr(*mi, SrcReg, DstReg))
+ ValNum = interval.getNextValue(~0U, 0);
+ else
+ ValNum = interval.getNextValue(defIndex, SrcReg);
+
+ LiveRange LR(defIndex,
+ getInstructionIndex(&mbb->back()) + InstrSlots::NUM, ValNum);
+ interval.addRange(LR);
+ DOUT << " +" << LR;
}
+ }
- DEBUG(std::cerr << '\n');
+ DOUT << '\n';
}
-void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock* mbb,
+void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock *MBB,
MachineBasicBlock::iterator mi,
- LiveInterval& interval)
-{
- // A physical register cannot be live across basic block, so its
- // lifetime must end somewhere in its defining basic block.
- DEBUG(std::cerr << "\t\tregister: "; printRegName(interval.reg));
- typedef LiveVariables::killed_iterator KillIter;
-
- MachineBasicBlock::iterator e = mbb->end();
- unsigned baseIndex = getInstructionIndex(mi);
- unsigned start = getDefIndex(baseIndex);
- unsigned end = start;
-
- // If it is not used after definition, it is considered dead at
- // the instruction defining it. Hence its interval is:
- // [defSlot(def), defSlot(def)+1)
- for (KillIter ki = lv_->dead_begin(mi), ke = lv_->dead_end(mi);
- ki != ke; ++ki) {
- if (interval.reg == ki->second) {
- DEBUG(std::cerr << " dead");
- end = getDefIndex(start) + 1;
- goto exit;
- }
+ unsigned MIIdx,
+ LiveInterval &interval,
+ unsigned SrcReg) {
+ // A physical register cannot be live across basic block, so its
+ // lifetime must end somewhere in its defining basic block.
+ DOUT << "\t\tregister: "; DEBUG(printRegName(interval.reg));
+
+ unsigned baseIndex = MIIdx;
+ unsigned start = getDefIndex(baseIndex);
+ unsigned end = start;
+
+ // If it is not used after definition, it is considered dead at
+ // the instruction defining it. Hence its interval is:
+ // [defSlot(def), defSlot(def)+1)
+ if (lv_->RegisterDefIsDead(mi, interval.reg)) {
+ DOUT << " dead";
+ end = getDefIndex(start) + 1;
+ goto exit;
+ }
+
+ // If it is not dead on definition, it must be killed by a
+ // subsequent instruction. Hence its interval is:
+ // [defSlot(def), useSlot(kill)+1)
+ while (++mi != MBB->end()) {
+ baseIndex += InstrSlots::NUM;
+ if (lv_->KillsRegister(mi, interval.reg)) {
+ DOUT << " killed";
+ end = getUseIndex(baseIndex) + 1;
+ goto exit;
+ } else if (lv_->ModifiesRegister(mi, interval.reg)) {
+ // Another instruction redefines the register before it is ever read.
+ // Then the register is essentially dead at the instruction that defines
+ // it. Hence its interval is:
+ // [defSlot(def), defSlot(def)+1)
+ DOUT << " dead";
+ end = getDefIndex(start) + 1;
+ goto exit;
}
-
- // If it is not dead on definition, it must be killed by a
- // subsequent instruction. Hence its interval is:
- // [defSlot(def), useSlot(kill)+1)
- do {
- ++mi;
- baseIndex += InstrSlots::NUM;
- for (KillIter ki = lv_->killed_begin(mi), ke = lv_->killed_end(mi);
- ki != ke; ++ki) {
- if (interval.reg == ki->second) {
- DEBUG(std::cerr << " killed");
- end = getUseIndex(baseIndex) + 1;
- goto exit;
- }
- }
- } while (mi != e);
+ }
+
+ // The only case we should have a dead physreg here without a killing or
+ // instruction where we know it's dead is if it is live-in to the function
+ // and never used.
+ assert(!SrcReg && "physreg was not killed in defining block!");
+ end = getDefIndex(start) + 1; // It's dead.
exit:
- assert(start < end && "did not find end of interval?");
- interval.addRange(start, end);
- DEBUG(std::cerr << '\n');
-}
+ assert(start < end && "did not find end of interval?");
-void LiveIntervals::handleRegisterDef(MachineBasicBlock* mbb,
- MachineBasicBlock::iterator mi,
- unsigned reg)
-{
- if (MRegisterInfo::isPhysicalRegister(reg)) {
- if (lv_->getAllocatablePhysicalRegisters()[reg]) {
- handlePhysicalRegisterDef(mbb, mi, getOrCreateInterval(reg));
- for (const unsigned* as = mri_->getAliasSet(reg); *as; ++as)
- handlePhysicalRegisterDef(mbb, mi, getOrCreateInterval(*as));
- }
- }
- else
- handleVirtualRegisterDef(mbb, mi, getOrCreateInterval(reg));
+ LiveRange LR(start, end, interval.getNextValue(SrcReg != 0 ? start : ~0U,
+ SrcReg));
+ interval.addRange(LR);
+ DOUT << " +" << LR << '\n';
}
-unsigned LiveIntervals::getInstructionIndex(MachineInstr* instr) const
-{
- Mi2IndexMap::const_iterator it = mi2iMap_.find(instr);
- return (it == mi2iMap_.end() ?
- std::numeric_limits<unsigned>::max() :
- it->second);
+void LiveIntervals::handleRegisterDef(MachineBasicBlock *MBB,
+ MachineBasicBlock::iterator MI,
+ unsigned MIIdx,
+ unsigned reg) {
+ if (MRegisterInfo::isVirtualRegister(reg))
+ handleVirtualRegisterDef(MBB, MI, MIIdx, getOrCreateInterval(reg));
+ else if (allocatableRegs_[reg]) {
+ unsigned SrcReg, DstReg;
+ if (!tii_->isMoveInstr(*MI, SrcReg, DstReg))
+ SrcReg = 0;
+ handlePhysicalRegisterDef(MBB, MI, MIIdx, getOrCreateInterval(reg), SrcReg);
+ for (const unsigned* AS = mri_->getAliasSet(reg); *AS; ++AS)
+ handlePhysicalRegisterDef(MBB, MI, MIIdx, getOrCreateInterval(*AS), 0);
+ }
}
-MachineInstr* LiveIntervals::getInstructionFromIndex(unsigned index) const
-{
- index /= InstrSlots::NUM; // convert index to vector index
- assert(index < i2miMap_.size() &&
- "index does not correspond to an instruction");
- return i2miMap_[index];
+void LiveIntervals::handleLiveInRegister(MachineBasicBlock *MBB,
+ unsigned MIIdx,
+ LiveInterval &interval) {
+ DOUT << "\t\tlivein register: "; DEBUG(printRegName(interval.reg));
+
+ // Look for kills, if it reaches a def before it's killed, then it shouldn't
+ // be considered a livein.
+ MachineBasicBlock::iterator mi = MBB->begin();
+ unsigned baseIndex = MIIdx;
+ unsigned start = baseIndex;
+ unsigned end = start;
+ while (mi != MBB->end()) {
+ if (lv_->KillsRegister(mi, interval.reg)) {
+ DOUT << " killed";
+ end = getUseIndex(baseIndex) + 1;
+ goto exit;
+ } else if (lv_->ModifiesRegister(mi, interval.reg)) {
+ // Another instruction redefines the register before it is ever read.
+ // Then the register is essentially dead at the instruction that defines
+ // it. Hence its interval is:
+ // [defSlot(def), defSlot(def)+1)
+ DOUT << " dead";
+ end = getDefIndex(start) + 1;
+ goto exit;
+ }
+
+ baseIndex += InstrSlots::NUM;
+ ++mi;
+ }
+
+exit:
+ assert(start < end && "did not find end of interval?");
+
+ LiveRange LR(start, end, interval.getNextValue(~0U, 0));
+ DOUT << " +" << LR << '\n';
+ interval.addRange(LR);
}
/// computeIntervals - computes the live intervals for virtual
/// registers. for some ordering of the machine instructions [1,N] a
/// live interval is an interval [i, j) where 1 <= i <= j < N for
/// which a variable is live
-void LiveIntervals::computeIntervals()
-{
- DEBUG(std::cerr << "********** COMPUTING LIVE INTERVALS **********\n");
- DEBUG(std::cerr << "********** Function: "
- << ((Value*)mf_->getFunction())->getName() << '\n');
-
- for (MachineFunction::iterator I = mf_->begin(), E = mf_->end();
- I != E; ++I) {
- MachineBasicBlock* mbb = I;
- DEBUG(std::cerr << ((Value*)mbb->getBasicBlock())->getName() << ":\n");
-
- for (MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
- mi != miEnd; ++mi) {
- const TargetInstrDescriptor& tid =
- tm_->getInstrInfo()->get(mi->getOpcode());
- DEBUG(std::cerr << getInstructionIndex(mi) << "\t";
- mi->print(std::cerr, tm_));
-
- // handle implicit defs
- for (const unsigned* id = tid.ImplicitDefs; *id; ++id)
- handleRegisterDef(mbb, mi, *id);
-
- // handle explicit defs
- for (int i = mi->getNumOperands() - 1; i >= 0; --i) {
- MachineOperand& mop = mi->getOperand(i);
- // handle register defs - build intervals
- if (mop.isRegister() && mop.getReg() && mop.isDef())
- handleRegisterDef(mbb, mi, mop.getReg());
- }
- }
+void LiveIntervals::computeIntervals() {
+ DOUT << "********** COMPUTING LIVE INTERVALS **********\n"
+ << "********** Function: "
+ << ((Value*)mf_->getFunction())->getName() << '\n';
+ // Track the index of the current machine instr.
+ unsigned MIIndex = 0;
+ for (MachineFunction::iterator MBBI = mf_->begin(), E = mf_->end();
+ MBBI != E; ++MBBI) {
+ MachineBasicBlock *MBB = MBBI;
+ DOUT << ((Value*)MBB->getBasicBlock())->getName() << ":\n";
+
+ MachineBasicBlock::iterator MI = MBB->begin(), miEnd = MBB->end();
+
+ if (MBB->livein_begin() != MBB->livein_end()) {
+ // Create intervals for live-ins to this BB first.
+ for (MachineBasicBlock::const_livein_iterator LI = MBB->livein_begin(),
+ LE = MBB->livein_end(); LI != LE; ++LI) {
+ handleLiveInRegister(MBB, MIIndex, getOrCreateInterval(*LI));
+ for (const unsigned* AS = mri_->getAliasSet(*LI); *AS; ++AS)
+ handleLiveInRegister(MBB, MIIndex, getOrCreateInterval(*AS));
+ }
+ }
+
+ for (; MI != miEnd; ++MI) {
+ DOUT << MIIndex << "\t" << *MI;
+
+ // Handle defs.
+ for (int i = MI->getNumOperands() - 1; i >= 0; --i) {
+ MachineOperand &MO = MI->getOperand(i);
+ // handle register defs - build intervals
+ if (MO.isRegister() && MO.getReg() && MO.isDef())
+ handleRegisterDef(MBB, MI, MIIndex, MO.getReg());
+ }
+
+ MIIndex += InstrSlots::NUM;
}
+ }
}
-unsigned LiveIntervals::rep(unsigned reg)
-{
- Reg2RegMap::iterator it = r2rMap_.find(reg);
- if (it != r2rMap_.end())
- return it->second = rep(it->second);
- return reg;
+/// AdjustCopiesBackFrom - We found a non-trivially-coallescable copy with IntA
+/// being the source and IntB being the dest, thus this defines a value number
+/// in IntB. If the source value number (in IntA) is defined by a copy from B,
+/// see if we can merge these two pieces of B into a single value number,
+/// eliminating a copy. For example:
+///
+/// A3 = B0
+/// ...
+/// B1 = A3 <- this copy
+///
+/// In this case, B0 can be extended to where the B1 copy lives, allowing the B1
+/// value number to be replaced with B0 (which simplifies the B liveinterval).
+///
+/// This returns true if an interval was modified.
+///
+bool LiveIntervals::AdjustCopiesBackFrom(LiveInterval &IntA, LiveInterval &IntB,
+ MachineInstr *CopyMI) {
+ unsigned CopyIdx = getDefIndex(getInstructionIndex(CopyMI));
+
+ // BValNo is a value number in B that is defined by a copy from A. 'B3' in
+ // the example above.
+ LiveInterval::iterator BLR = IntB.FindLiveRangeContaining(CopyIdx);
+ unsigned BValNo = BLR->ValId;
+
+ // Get the location that B is defined at. Two options: either this value has
+ // an unknown definition point or it is defined at CopyIdx. If unknown, we
+ // can't process it.
+ unsigned BValNoDefIdx = IntB.getInstForValNum(BValNo);
+ if (BValNoDefIdx == ~0U) return false;
+ assert(BValNoDefIdx == CopyIdx &&
+ "Copy doesn't define the value?");
+
+ // AValNo is the value number in A that defines the copy, A0 in the example.
+ LiveInterval::iterator AValLR = IntA.FindLiveRangeContaining(CopyIdx-1);
+ unsigned AValNo = AValLR->ValId;
+
+ // If AValNo is defined as a copy from IntB, we can potentially process this.
+
+ // Get the instruction that defines this value number.
+ unsigned SrcReg = IntA.getSrcRegForValNum(AValNo);
+ if (!SrcReg) return false; // Not defined by a copy.
+
+ // If the value number is not defined by a copy instruction, ignore it.
+
+ // If the source register comes from an interval other than IntB, we can't
+ // handle this.
+ if (rep(SrcReg) != IntB.reg) return false;
+
+ // Get the LiveRange in IntB that this value number starts with.
+ unsigned AValNoInstIdx = IntA.getInstForValNum(AValNo);
+ LiveInterval::iterator ValLR = IntB.FindLiveRangeContaining(AValNoInstIdx-1);
+
+ // Make sure that the end of the live range is inside the same block as
+ // CopyMI.
+ MachineInstr *ValLREndInst = getInstructionFromIndex(ValLR->end-1);
+ if (!ValLREndInst ||
+ ValLREndInst->getParent() != CopyMI->getParent()) return false;
+
+ // Okay, we now know that ValLR ends in the same block that the CopyMI
+ // live-range starts. If there are no intervening live ranges between them in
+ // IntB, we can merge them.
+ if (ValLR+1 != BLR) return false;
+
+ DOUT << "\nExtending: "; IntB.print(DOUT, mri_);
+
+ // We are about to delete CopyMI, so need to remove it as the 'instruction
+ // that defines this value #'.
+ IntB.setValueNumberInfo(BValNo, std::make_pair(~0U, 0));
+
+ // Okay, we can merge them. We need to insert a new liverange:
+ // [ValLR.end, BLR.begin) of either value number, then we merge the
+ // two value numbers.
+ unsigned FillerStart = ValLR->end, FillerEnd = BLR->start;
+ IntB.addRange(LiveRange(FillerStart, FillerEnd, BValNo));
+
+ // If the IntB live range is assigned to a physical register, and if that
+ // physreg has aliases,
+ if (MRegisterInfo::isPhysicalRegister(IntB.reg)) {
+ for (const unsigned *AS = mri_->getAliasSet(IntB.reg); *AS; ++AS) {
+ LiveInterval &AliasLI = getInterval(*AS);
+ AliasLI.addRange(LiveRange(FillerStart, FillerEnd,
+ AliasLI.getNextValue(~0U, 0)));
+ }
+ }
+
+ // Okay, merge "B1" into the same value number as "B0".
+ if (BValNo != ValLR->ValId)
+ IntB.MergeValueNumberInto(BValNo, ValLR->ValId);
+ DOUT << " result = "; IntB.print(DOUT, mri_);
+ DOUT << "\n";
+
+ // If the source instruction was killing the source register before the
+ // merge, unset the isKill marker given the live range has been extended.
+ int UIdx = ValLREndInst->findRegisterUseOperand(IntB.reg, true);
+ if (UIdx != -1)
+ ValLREndInst->getOperand(UIdx).unsetIsKill();
+
+ // Finally, delete the copy instruction.
+ RemoveMachineInstrFromMaps(CopyMI);
+ CopyMI->eraseFromParent();
+ ++numPeep;
+ return true;
}
-void LiveIntervals::joinIntervals()
-{
- DEBUG(std::cerr << "********** JOINING INTERVALS ***********\n");
-
- const TargetInstrInfo& tii = *tm_->getInstrInfo();
-
- for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
- mbbi != mbbe; ++mbbi) {
- MachineBasicBlock* mbb = mbbi;
- DEBUG(std::cerr << ((Value*)mbb->getBasicBlock())->getName() << ":\n");
-
- for (MachineBasicBlock::iterator mi = mbb->begin(), mie = mbb->end();
- mi != mie; ++mi) {
- const TargetInstrDescriptor& tid = tii.get(mi->getOpcode());
- DEBUG(std::cerr << getInstructionIndex(mi) << '\t';
- mi->print(std::cerr, tm_););
-
- // we only join virtual registers with allocatable
- // physical registers since we do not have liveness information
- // on not allocatable physical registers
- unsigned regA, regB;
- if (tii.isMoveInstr(*mi, regA, regB) &&
- (MRegisterInfo::isVirtualRegister(regA) ||
- lv_->getAllocatablePhysicalRegisters()[regA]) &&
- (MRegisterInfo::isVirtualRegister(regB) ||
- lv_->getAllocatablePhysicalRegisters()[regB])) {
-
- // get representative registers
- regA = rep(regA);
- regB = rep(regB);
-
- // if they are already joined we continue
- if (regA == regB)
- continue;
-
- Reg2IntervalMap::iterator r2iA = r2iMap_.find(regA);
- assert(r2iA != r2iMap_.end() &&
- "Found unknown vreg in 'isMoveInstr' instruction");
- Reg2IntervalMap::iterator r2iB = r2iMap_.find(regB);
- assert(r2iB != r2iMap_.end() &&
- "Found unknown vreg in 'isMoveInstr' instruction");
-
- Intervals::iterator intA = r2iA->second;
- Intervals::iterator intB = r2iB->second;
-
- // both A and B are virtual registers
- if (MRegisterInfo::isVirtualRegister(intA->reg) &&
- MRegisterInfo::isVirtualRegister(intB->reg)) {
-
- const TargetRegisterClass *rcA, *rcB;
- rcA = mf_->getSSARegMap()->getRegClass(intA->reg);
- rcB = mf_->getSSARegMap()->getRegClass(intB->reg);
- // if they are not of the same register class we continue
- if (rcA != rcB)
- continue;
-
- // if their intervals do not overlap we join them
- if (!intB->overlaps(*intA)) {
- intA->join(*intB);
- r2iB->second = r2iA->second;
- r2rMap_.insert(std::make_pair(intB->reg, intA->reg));
- intervals_.erase(intB);
- }
- } else if (MRegisterInfo::isPhysicalRegister(intA->reg) ^
- MRegisterInfo::isPhysicalRegister(intB->reg)) {
- if (MRegisterInfo::isPhysicalRegister(intB->reg)) {
- std::swap(regA, regB);
- std::swap(intA, intB);
- std::swap(r2iA, r2iB);
- }
-
- assert(MRegisterInfo::isPhysicalRegister(intA->reg) &&
- MRegisterInfo::isVirtualRegister(intB->reg) &&
- "A must be physical and B must be virtual");
-
- const TargetRegisterClass *rcA, *rcB;
- rcA = mri_->getRegClass(intA->reg);
- rcB = mf_->getSSARegMap()->getRegClass(intB->reg);
- // if they are not of the same register class we continue
- if (rcA != rcB)
- continue;
-
- if (!intA->overlaps(*intB) &&
- !overlapsAliases(*intA, *intB)) {
- intA->join(*intB);
- r2iB->second = r2iA->second;
- r2rMap_.insert(std::make_pair(intB->reg, intA->reg));
- intervals_.erase(intB);
- }
- }
- }
+/// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
+/// which are the src/dst of the copy instruction CopyMI. This returns true
+/// if the copy was successfully coallesced away, or if it is never possible
+/// to coallesce these this copy, due to register constraints. It returns
+/// false if it is not currently possible to coallesce this interval, but
+/// it may be possible if other things get coallesced.
+bool LiveIntervals::JoinCopy(MachineInstr *CopyMI,
+ unsigned SrcReg, unsigned DstReg) {
+ DOUT << getInstructionIndex(CopyMI) << '\t' << *CopyMI;
+
+ // Get representative registers.
+ unsigned repSrcReg = rep(SrcReg);
+ unsigned repDstReg = rep(DstReg);
+
+ // If they are already joined we continue.
+ if (repSrcReg == repDstReg) {
+ DOUT << "\tCopy already coallesced.\n";
+ return true; // Not coallescable.
+ }
+
+ // If they are both physical registers, we cannot join them.
+ if (MRegisterInfo::isPhysicalRegister(repSrcReg) &&
+ MRegisterInfo::isPhysicalRegister(repDstReg)) {
+ DOUT << "\tCan not coallesce physregs.\n";
+ return true; // Not coallescable.
+ }
+
+ // We only join virtual registers with allocatable physical registers.
+ if (MRegisterInfo::isPhysicalRegister(repSrcReg) &&
+ !allocatableRegs_[repSrcReg]) {
+ DOUT << "\tSrc reg is unallocatable physreg.\n";
+ return true; // Not coallescable.
+ }
+ if (MRegisterInfo::isPhysicalRegister(repDstReg) &&
+ !allocatableRegs_[repDstReg]) {
+ DOUT << "\tDst reg is unallocatable physreg.\n";
+ return true; // Not coallescable.
+ }
+
+ // If they are not of the same register class, we cannot join them.
+ if (differingRegisterClasses(repSrcReg, repDstReg)) {
+ DOUT << "\tSrc/Dest are different register classes.\n";
+ return true; // Not coallescable.
+ }
+
+ LiveInterval &SrcInt = getInterval(repSrcReg);
+ LiveInterval &DestInt = getInterval(repDstReg);
+ assert(SrcInt.reg == repSrcReg && DestInt.reg == repDstReg &&
+ "Register mapping is horribly broken!");
+
+ DOUT << "\t\tInspecting "; SrcInt.print(DOUT, mri_);
+ DOUT << " and "; DestInt.print(DOUT, mri_);
+ DOUT << ": ";
+
+ // Check if it is necessary to propagate "isDead" property before intervals
+ // are joined.
+ MachineBasicBlock *CopyBB = CopyMI->getParent();
+ MachineOperand *mopd = CopyMI->findRegisterDefOperand(DstReg);
+ bool isDead = mopd->isDead();
+ bool isShorten = false;
+ unsigned SrcStart = 0, RemoveStart = 0;
+ unsigned SrcEnd = 0, RemoveEnd = 0;
+ if (isDead) {
+ unsigned CopyIdx = getInstructionIndex(CopyMI);
+ LiveInterval::iterator SrcLR =
+ SrcInt.FindLiveRangeContaining(getUseIndex(CopyIdx));
+ RemoveStart = SrcStart = SrcLR->start;
+ RemoveEnd = SrcEnd = SrcLR->end;
+ // The instruction which defines the src is only truly dead if there are
+ // no intermediate uses and there isn't a use beyond the copy.
+ // FIXME: find the last use, mark is kill and shorten the live range.
+ if (SrcEnd > getDefIndex(CopyIdx)) {
+ isDead = false;
+ } else {
+ MachineOperand *MOU;
+ MachineInstr *LastUse= lastRegisterUse(repSrcReg, SrcStart, CopyIdx, MOU);
+ if (LastUse) {
+ // Shorten the liveinterval to the end of last use.
+ MOU->setIsKill();
+ isDead = false;
+ isShorten = true;
+ RemoveStart = getDefIndex(getInstructionIndex(LastUse));
+ RemoveEnd = SrcEnd;
+ } else {
+ MachineInstr *SrcMI = getInstructionFromIndex(SrcStart);
+ if (SrcMI) {
+ MachineOperand *mops = findDefOperand(SrcMI, repSrcReg);
+ if (mops)
+ // A dead def should have a single cycle interval.
+ ++RemoveStart;
}
+ }
+ }
+ }
+
+ // We need to be careful about coalescing a source physical register with a
+ // virtual register. Once the coalescing is done, it cannot be broken and
+ // these are not spillable! If the destination interval uses are far away,
+ // think twice about coalescing them!
+ if (!mopd->isDead() && MRegisterInfo::isPhysicalRegister(repSrcReg)) {
+ // Small function. No need to worry!
+ unsigned Threshold = allocatableRegs_.count() * 2;
+ if (r2iMap_.size() <= Threshold)
+ goto TryJoin;
+
+ LiveVariables::VarInfo& dvi = lv_->getVarInfo(repDstReg);
+ // Is the value used in the current BB or any immediate successroe BB?
+ if (dvi.UsedBlocks[CopyBB->getNumber()])
+ goto TryJoin;
+ for (MachineBasicBlock::succ_iterator SI = CopyBB->succ_begin(),
+ SE = CopyBB->succ_end(); SI != SE; ++SI) {
+ MachineBasicBlock *SuccMBB = *SI;
+ if (dvi.UsedBlocks[SuccMBB->getNumber()])
+ goto TryJoin;
}
-}
-bool LiveIntervals::overlapsAliases(const LiveInterval& lhs,
- const LiveInterval& rhs) const
-{
- assert(MRegisterInfo::isPhysicalRegister(lhs.reg) &&
- "first interval must describe a physical register");
+ // Ok, no use in this BB and no use in immediate successor BB's. Be really
+ // careful now!
+ // It's only used in one BB, forget about it!
+ if (dvi.UsedBlocks.count() < 2) {
+ ++numAborts;
+ return false;
+ }
- for (const unsigned* as = mri_->getAliasSet(lhs.reg); *as; ++as) {
- Reg2IntervalMap::const_iterator r2i = r2iMap_.find(*as);
- assert(r2i != r2iMap_.end() && "alias does not have interval?");
- if (rhs.overlaps(*r2i->second))
- return true;
+ // Determine whether to allow coalescing based on how far the closest
+ // use is.
+ unsigned CopyIdx = getInstructionIndex(CopyMI);
+ unsigned MinDist = i2miMap_.size() * InstrSlots::NUM;
+ int UseBBNum = dvi.UsedBlocks.find_first();
+ while (UseBBNum != -1) {
+ MachineBasicBlock *UseBB = mf_->getBlockNumbered(UseBBNum);
+ unsigned UseIdx = getMBBStartIdx(UseBB);
+ if (UseIdx > CopyIdx) {
+ MinDist = std::min(MinDist, UseIdx - CopyIdx);
+ if (MinDist <= Threshold)
+ break;
+ }
+ UseBBNum = dvi.UsedBlocks.find_next(UseBBNum);
+ }
+ if (MinDist > Threshold) {
+ // Don't do it!
+ ++numAborts;
+ return false;
+ }
+ }
+
+TryJoin:
+ // Okay, attempt to join these two intervals. On failure, this returns false.
+ // Otherwise, if one of the intervals being joined is a physreg, this method
+ // always canonicalizes DestInt to be it. The output "SrcInt" will not have
+ // been modified, so we can use this information below to update aliases.
+ if (JoinIntervals(DestInt, SrcInt)) {
+ if (isDead) {
+ // Result of the copy is dead. Propagate this property.
+ if (SrcStart == 0) {
+ assert(MRegisterInfo::isPhysicalRegister(repSrcReg) &&
+ "Live-in must be a physical register!");
+ // Live-in to the function but dead. Remove it from entry live-in set.
+ // JoinIntervals may end up swapping the two intervals.
+ mf_->begin()->removeLiveIn(repSrcReg);
+ } else {
+ MachineInstr *SrcMI = getInstructionFromIndex(SrcStart);
+ if (SrcMI) {
+ MachineOperand *mops = findDefOperand(SrcMI, repSrcReg);
+ if (mops)
+ mops->setIsDead();
+ }
+ }
}
+ if (isShorten || isDead) {
+ // Shorten the live interval.
+ LiveInterval &LiveInInt = (repSrcReg == DestInt.reg) ? DestInt : SrcInt;
+ LiveInInt.removeRange(RemoveStart, RemoveEnd);
+ }
+ } else {
+ // Coallescing failed.
+
+ // If we can eliminate the copy without merging the live ranges, do so now.
+ if (AdjustCopiesBackFrom(SrcInt, DestInt, CopyMI))
+ return true;
+
+ // Otherwise, we are unable to join the intervals.
+ DOUT << "Interference!\n";
return false;
+ }
+
+ bool Swapped = repSrcReg == DestInt.reg;
+ if (Swapped)
+ std::swap(repSrcReg, repDstReg);
+ assert(MRegisterInfo::isVirtualRegister(repSrcReg) &&
+ "LiveInterval::join didn't work right!");
+
+ // If we're about to merge live ranges into a physical register live range,
+ // we have to update any aliased register's live ranges to indicate that they
+ // have clobbered values for this range.
+ if (MRegisterInfo::isPhysicalRegister(repDstReg)) {
+ for (const unsigned *AS = mri_->getAliasSet(repDstReg); *AS; ++AS)
+ getInterval(*AS).MergeInClobberRanges(SrcInt);
+ } else {
+ // Merge UsedBlocks info if the destination is a virtual register.
+ LiveVariables::VarInfo& dVI = lv_->getVarInfo(repDstReg);
+ LiveVariables::VarInfo& sVI = lv_->getVarInfo(repSrcReg);
+ dVI.UsedBlocks |= sVI.UsedBlocks;
+ }
+
+ DOUT << "\n\t\tJoined. Result = "; DestInt.print(DOUT, mri_);
+ DOUT << "\n";
+
+ // Remember these liveintervals have been joined.
+ JoinedLIs.set(repSrcReg - MRegisterInfo::FirstVirtualRegister);
+ if (MRegisterInfo::isVirtualRegister(repDstReg))
+ JoinedLIs.set(repDstReg - MRegisterInfo::FirstVirtualRegister);
+
+ // If the intervals were swapped by Join, swap them back so that the register
+ // mapping (in the r2i map) is correct.
+ if (Swapped) SrcInt.swap(DestInt);
+ removeInterval(repSrcReg);
+ r2rMap_[repSrcReg] = repDstReg;
+
+ // Finally, delete the copy instruction.
+ RemoveMachineInstrFromMaps(CopyMI);
+ CopyMI->eraseFromParent();
+ ++numPeep;
+ ++numJoins;
+ return true;
}
-LiveInterval& LiveIntervals::getOrCreateInterval(unsigned reg)
-{
- Reg2IntervalMap::iterator r2iit = r2iMap_.lower_bound(reg);
- if (r2iit == r2iMap_.end() || r2iit->first != reg) {
- intervals_.push_back(LiveInterval(reg));
- r2iit = r2iMap_.insert(r2iit, std::make_pair(reg, --intervals_.end()));
- }
-
- return *r2iit->second;
+/// ComputeUltimateVN - Assuming we are going to join two live intervals,
+/// compute what the resultant value numbers for each value in the input two
+/// ranges will be. This is complicated by copies between the two which can
+/// and will commonly cause multiple value numbers to be merged into one.
+///
+/// VN is the value number that we're trying to resolve. InstDefiningValue
+/// keeps track of the new InstDefiningValue assignment for the result
+/// LiveInterval. ThisFromOther/OtherFromThis are sets that keep track of
+/// whether a value in this or other is a copy from the opposite set.
+/// ThisValNoAssignments/OtherValNoAssignments keep track of value #'s that have
+/// already been assigned.
+///
+/// ThisFromOther[x] - If x is defined as a copy from the other interval, this
+/// contains the value number the copy is from.
+///
+static unsigned ComputeUltimateVN(unsigned VN,
+ SmallVector<std::pair<unsigned,
+ unsigned>, 16> &ValueNumberInfo,
+ SmallVector<int, 16> &ThisFromOther,
+ SmallVector<int, 16> &OtherFromThis,
+ SmallVector<int, 16> &ThisValNoAssignments,
+ SmallVector<int, 16> &OtherValNoAssignments,
+ LiveInterval &ThisLI, LiveInterval &OtherLI) {
+ // If the VN has already been computed, just return it.
+ if (ThisValNoAssignments[VN] >= 0)
+ return ThisValNoAssignments[VN];
+// assert(ThisValNoAssignments[VN] != -2 && "Cyclic case?");
+
+ // If this val is not a copy from the other val, then it must be a new value
+ // number in the destination.
+ int OtherValNo = ThisFromOther[VN];
+ if (OtherValNo == -1) {
+ ValueNumberInfo.push_back(ThisLI.getValNumInfo(VN));
+ return ThisValNoAssignments[VN] = ValueNumberInfo.size()-1;
+ }
+
+ // Otherwise, this *is* a copy from the RHS. If the other side has already
+ // been computed, return it.
+ if (OtherValNoAssignments[OtherValNo] >= 0)
+ return ThisValNoAssignments[VN] = OtherValNoAssignments[OtherValNo];
+
+ // Mark this value number as currently being computed, then ask what the
+ // ultimate value # of the other value is.
+ ThisValNoAssignments[VN] = -2;
+ unsigned UltimateVN =
+ ComputeUltimateVN(OtherValNo, ValueNumberInfo,
+ OtherFromThis, ThisFromOther,
+ OtherValNoAssignments, ThisValNoAssignments,
+ OtherLI, ThisLI);
+ return ThisValNoAssignments[VN] = UltimateVN;
}
-LiveInterval::LiveInterval(unsigned r)
- : reg(r),
- weight((MRegisterInfo::isPhysicalRegister(r) ? HUGE_VAL : 0.0F))
-{
+static bool InVector(unsigned Val, const SmallVector<unsigned, 8> &V) {
+ return std::find(V.begin(), V.end(), Val) != V.end();
}
-bool LiveInterval::spilled() const
-{
- return (weight == HUGE_VAL &&
- MRegisterInfo::isVirtualRegister(reg));
+/// SimpleJoin - Attempt to joint the specified interval into this one. The
+/// caller of this method must guarantee that the RHS only contains a single
+/// value number and that the RHS is not defined by a copy from this
+/// interval. This returns false if the intervals are not joinable, or it
+/// joins them and returns true.
+bool LiveIntervals::SimpleJoin(LiveInterval &LHS, LiveInterval &RHS) {
+ assert(RHS.containsOneValue());
+
+ // Some number (potentially more than one) value numbers in the current
+ // interval may be defined as copies from the RHS. Scan the overlapping
+ // portions of the LHS and RHS, keeping track of this and looking for
+ // overlapping live ranges that are NOT defined as copies. If these exist, we
+ // cannot coallesce.
+
+ LiveInterval::iterator LHSIt = LHS.begin(), LHSEnd = LHS.end();
+ LiveInterval::iterator RHSIt = RHS.begin(), RHSEnd = RHS.end();
+
+ if (LHSIt->start < RHSIt->start) {
+ LHSIt = std::upper_bound(LHSIt, LHSEnd, RHSIt->start);
+ if (LHSIt != LHS.begin()) --LHSIt;
+ } else if (RHSIt->start < LHSIt->start) {
+ RHSIt = std::upper_bound(RHSIt, RHSEnd, LHSIt->start);
+ if (RHSIt != RHS.begin()) --RHSIt;
+ }
+
+ SmallVector<unsigned, 8> EliminatedLHSVals;
+
+ while (1) {
+ // Determine if these live intervals overlap.
+ bool Overlaps = false;
+ if (LHSIt->start <= RHSIt->start)
+ Overlaps = LHSIt->end > RHSIt->start;
+ else
+ Overlaps = RHSIt->end > LHSIt->start;
+
+ // If the live intervals overlap, there are two interesting cases: if the
+ // LHS interval is defined by a copy from the RHS, it's ok and we record
+ // that the LHS value # is the same as the RHS. If it's not, then we cannot
+ // coallesce these live ranges and we bail out.
+ if (Overlaps) {
+ // If we haven't already recorded that this value # is safe, check it.
+ if (!InVector(LHSIt->ValId, EliminatedLHSVals)) {
+ // Copy from the RHS?
+ unsigned SrcReg = LHS.getSrcRegForValNum(LHSIt->ValId);
+ if (rep(SrcReg) != RHS.reg)
+ return false; // Nope, bail out.
+
+ EliminatedLHSVals.push_back(LHSIt->ValId);
+ }
+
+ // We know this entire LHS live range is okay, so skip it now.
+ if (++LHSIt == LHSEnd) break;
+ continue;
+ }
+
+ if (LHSIt->end < RHSIt->end) {
+ if (++LHSIt == LHSEnd) break;
+ } else {
+ // One interesting case to check here. It's possible that we have
+ // something like "X3 = Y" which defines a new value number in the LHS,
+ // and is the last use of this liverange of the RHS. In this case, we
+ // want to notice this copy (so that it gets coallesced away) even though
+ // the live ranges don't actually overlap.
+ if (LHSIt->start == RHSIt->end) {
+ if (InVector(LHSIt->ValId, EliminatedLHSVals)) {
+ // We already know that this value number is going to be merged in
+ // if coallescing succeeds. Just skip the liverange.
+ if (++LHSIt == LHSEnd) break;
+ } else {
+ // Otherwise, if this is a copy from the RHS, mark it as being merged
+ // in.
+ if (rep(LHS.getSrcRegForValNum(LHSIt->ValId)) == RHS.reg) {
+ EliminatedLHSVals.push_back(LHSIt->ValId);
+
+ // We know this entire LHS live range is okay, so skip it now.
+ if (++LHSIt == LHSEnd) break;
+ }
+ }
+ }
+
+ if (++RHSIt == RHSEnd) break;
+ }
+ }
+
+ // If we got here, we know that the coallescing will be successful and that
+ // the value numbers in EliminatedLHSVals will all be merged together. Since
+ // the most common case is that EliminatedLHSVals has a single number, we
+ // optimize for it: if there is more than one value, we merge them all into
+ // the lowest numbered one, then handle the interval as if we were merging
+ // with one value number.
+ unsigned LHSValNo;
+ if (EliminatedLHSVals.size() > 1) {
+ // Loop through all the equal value numbers merging them into the smallest
+ // one.
+ unsigned Smallest = EliminatedLHSVals[0];
+ for (unsigned i = 1, e = EliminatedLHSVals.size(); i != e; ++i) {
+ if (EliminatedLHSVals[i] < Smallest) {
+ // Merge the current notion of the smallest into the smaller one.
+ LHS.MergeValueNumberInto(Smallest, EliminatedLHSVals[i]);
+ Smallest = EliminatedLHSVals[i];
+ } else {
+ // Merge into the smallest.
+ LHS.MergeValueNumberInto(EliminatedLHSVals[i], Smallest);
+ }
+ }
+ LHSValNo = Smallest;
+ } else {
+ assert(!EliminatedLHSVals.empty() && "No copies from the RHS?");
+ LHSValNo = EliminatedLHSVals[0];
+ }
+
+ // Okay, now that there is a single LHS value number that we're merging the
+ // RHS into, update the value number info for the LHS to indicate that the
+ // value number is defined where the RHS value number was.
+ LHS.setValueNumberInfo(LHSValNo, RHS.getValNumInfo(0));
+
+ // Okay, the final step is to loop over the RHS live intervals, adding them to
+ // the LHS.
+ LHS.MergeRangesInAsValue(RHS, LHSValNo);
+ LHS.weight += RHS.weight;
+
+ return true;
}
-// An example for liveAt():
-//
-// this = [1,4), liveAt(0) will return false. The instruction defining
-// this spans slots [0,3]. The interval belongs to an spilled
-// definition of the variable it represents. This is because slot 1 is
-// used (def slot) and spans up to slot 3 (store slot).
-//
-bool LiveInterval::liveAt(unsigned index) const
-{
- Range dummy(index, index+1);
- Ranges::const_iterator r = std::upper_bound(ranges.begin(),
- ranges.end(),
- dummy);
- if (r == ranges.begin())
+/// JoinIntervals - Attempt to join these two intervals. On failure, this
+/// returns false. Otherwise, if one of the intervals being joined is a
+/// physreg, this method always canonicalizes LHS to be it. The output
+/// "RHS" will not have been modified, so we can use this information
+/// below to update aliases.
+bool LiveIntervals::JoinIntervals(LiveInterval &LHS, LiveInterval &RHS) {
+ // Compute the final value assignment, assuming that the live ranges can be
+ // coallesced.
+ SmallVector<int, 16> LHSValNoAssignments;
+ SmallVector<int, 16> RHSValNoAssignments;
+ SmallVector<std::pair<unsigned,unsigned>, 16> ValueNumberInfo;
+
+ // Compute ultimate value numbers for the LHS and RHS values.
+ if (RHS.containsOneValue()) {
+ // Copies from a liveinterval with a single value are simple to handle and
+ // very common, handle the special case here. This is important, because
+ // often RHS is small and LHS is large (e.g. a physreg).
+
+ // Find out if the RHS is defined as a copy from some value in the LHS.
+ int RHSValID = -1;
+ std::pair<unsigned,unsigned> RHSValNoInfo;
+ unsigned RHSSrcReg = RHS.getSrcRegForValNum(0);
+ if ((RHSSrcReg == 0 || rep(RHSSrcReg) != LHS.reg)) {
+ // If RHS is not defined as a copy from the LHS, we can use simpler and
+ // faster checks to see if the live ranges are coallescable. This joiner
+ // can't swap the LHS/RHS intervals though.
+ if (!MRegisterInfo::isPhysicalRegister(RHS.reg)) {
+ return SimpleJoin(LHS, RHS);
+ } else {
+ RHSValNoInfo = RHS.getValNumInfo(0);
+ }
+ } else {
+ // It was defined as a copy from the LHS, find out what value # it is.
+ unsigned ValInst = RHS.getInstForValNum(0);
+ RHSValID = LHS.getLiveRangeContaining(ValInst-1)->ValId;
+ RHSValNoInfo = LHS.getValNumInfo(RHSValID);
+ }
+
+ LHSValNoAssignments.resize(LHS.getNumValNums(), -1);
+ RHSValNoAssignments.resize(RHS.getNumValNums(), -1);
+ ValueNumberInfo.resize(LHS.getNumValNums());
+
+ // Okay, *all* of the values in LHS that are defined as a copy from RHS
+ // should now get updated.
+ for (unsigned VN = 0, e = LHS.getNumValNums(); VN != e; ++VN) {
+ if (unsigned LHSSrcReg = LHS.getSrcRegForValNum(VN)) {
+ if (rep(LHSSrcReg) != RHS.reg) {
+ // If this is not a copy from the RHS, its value number will be
+ // unmodified by the coallescing.
+ ValueNumberInfo[VN] = LHS.getValNumInfo(VN);
+ LHSValNoAssignments[VN] = VN;
+ } else if (RHSValID == -1) {
+ // Otherwise, it is a copy from the RHS, and we don't already have a
+ // value# for it. Keep the current value number, but remember it.
+ LHSValNoAssignments[VN] = RHSValID = VN;
+ ValueNumberInfo[VN] = RHSValNoInfo;
+ } else {
+ // Otherwise, use the specified value #.
+ LHSValNoAssignments[VN] = RHSValID;
+ if (VN != (unsigned)RHSValID)
+ ValueNumberInfo[VN].first = ~1U;
+ else
+ ValueNumberInfo[VN] = RHSValNoInfo;
+ }
+ } else {
+ ValueNumberInfo[VN] = LHS.getValNumInfo(VN);
+ LHSValNoAssignments[VN] = VN;
+ }
+ }
+
+ assert(RHSValID != -1 && "Didn't find value #?");
+ RHSValNoAssignments[0] = RHSValID;
+
+ } else {
+ // Loop over the value numbers of the LHS, seeing if any are defined from
+ // the RHS.
+ SmallVector<int, 16> LHSValsDefinedFromRHS;
+ LHSValsDefinedFromRHS.resize(LHS.getNumValNums(), -1);
+ for (unsigned VN = 0, e = LHS.getNumValNums(); VN != e; ++VN) {
+ unsigned ValSrcReg = LHS.getSrcRegForValNum(VN);
+ if (ValSrcReg == 0) // Src not defined by a copy?
+ continue;
+
+ // DstReg is known to be a register in the LHS interval. If the src is
+ // from the RHS interval, we can use its value #.
+ if (rep(ValSrcReg) != RHS.reg)
+ continue;
+
+ // Figure out the value # from the RHS.
+ unsigned ValInst = LHS.getInstForValNum(VN);
+ LHSValsDefinedFromRHS[VN] = RHS.getLiveRangeContaining(ValInst-1)->ValId;
+ }
+
+ // Loop over the value numbers of the RHS, seeing if any are defined from
+ // the LHS.
+ SmallVector<int, 16> RHSValsDefinedFromLHS;
+ RHSValsDefinedFromLHS.resize(RHS.getNumValNums(), -1);
+ for (unsigned VN = 0, e = RHS.getNumValNums(); VN != e; ++VN) {
+ unsigned ValSrcReg = RHS.getSrcRegForValNum(VN);
+ if (ValSrcReg == 0) // Src not defined by a copy?
+ continue;
+
+ // DstReg is known to be a register in the RHS interval. If the src is
+ // from the LHS interval, we can use its value #.
+ if (rep(ValSrcReg) != LHS.reg)
+ continue;
+
+ // Figure out the value # from the LHS.
+ unsigned ValInst = RHS.getInstForValNum(VN);
+ RHSValsDefinedFromLHS[VN] = LHS.getLiveRangeContaining(ValInst-1)->ValId;
+ }
+
+ LHSValNoAssignments.resize(LHS.getNumValNums(), -1);
+ RHSValNoAssignments.resize(RHS.getNumValNums(), -1);
+ ValueNumberInfo.reserve(LHS.getNumValNums() + RHS.getNumValNums());
+
+ for (unsigned VN = 0, e = LHS.getNumValNums(); VN != e; ++VN) {
+ if (LHSValNoAssignments[VN] >= 0 || LHS.getInstForValNum(VN) == ~2U)
+ continue;
+ ComputeUltimateVN(VN, ValueNumberInfo,
+ LHSValsDefinedFromRHS, RHSValsDefinedFromLHS,
+ LHSValNoAssignments, RHSValNoAssignments, LHS, RHS);
+ }
+ for (unsigned VN = 0, e = RHS.getNumValNums(); VN != e; ++VN) {
+ if (RHSValNoAssignments[VN] >= 0 || RHS.getInstForValNum(VN) == ~2U)
+ continue;
+ // If this value number isn't a copy from the LHS, it's a new number.
+ if (RHSValsDefinedFromLHS[VN] == -1) {
+ ValueNumberInfo.push_back(RHS.getValNumInfo(VN));
+ RHSValNoAssignments[VN] = ValueNumberInfo.size()-1;
+ continue;
+ }
+
+ ComputeUltimateVN(VN, ValueNumberInfo,
+ RHSValsDefinedFromLHS, LHSValsDefinedFromRHS,
+ RHSValNoAssignments, LHSValNoAssignments, RHS, LHS);
+ }
+ }
+
+ // Armed with the mappings of LHS/RHS values to ultimate values, walk the
+ // interval lists to see if these intervals are coallescable.
+ LiveInterval::const_iterator I = LHS.begin();
+ LiveInterval::const_iterator IE = LHS.end();
+ LiveInterval::const_iterator J = RHS.begin();
+ LiveInterval::const_iterator JE = RHS.end();
+
+ // Skip ahead until the first place of potential sharing.
+ if (I->start < J->start) {
+ I = std::upper_bound(I, IE, J->start);
+ if (I != LHS.begin()) --I;
+ } else if (J->start < I->start) {
+ J = std::upper_bound(J, JE, I->start);
+ if (J != RHS.begin()) --J;
+ }
+
+ while (1) {
+ // Determine if these two live ranges overlap.
+ bool Overlaps;
+ if (I->start < J->start) {
+ Overlaps = I->end > J->start;
+ } else {
+ Overlaps = J->end > I->start;
+ }
+
+ // If so, check value # info to determine if they are really different.
+ if (Overlaps) {
+ // If the live range overlap will map to the same value number in the
+ // result liverange, we can still coallesce them. If not, we can't.
+ if (LHSValNoAssignments[I->ValId] != RHSValNoAssignments[J->ValId])
return false;
+ }
+
+ if (I->end < J->end) {
+ ++I;
+ if (I == IE) break;
+ } else {
+ ++J;
+ if (J == JE) break;
+ }
+ }
- --r;
- return index >= r->first && index < r->second;
+ // If we get here, we know that we can coallesce the live ranges. Ask the
+ // intervals to coallesce themselves now.
+ LHS.join(RHS, &LHSValNoAssignments[0], &RHSValNoAssignments[0],
+ ValueNumberInfo);
+ return true;
}
-// An example for overlaps():
-//
-// 0: A = ...
-// 4: B = ...
-// 8: C = A + B ;; last use of A
-//
-// The live intervals should look like:
-//
-// A = [3, 11)
-// B = [7, x)
-// C = [11, y)
-//
-// A->overlaps(C) should return false since we want to be able to join
-// A and C.
-bool LiveInterval::overlaps(const LiveInterval& other) const
-{
- Ranges::const_iterator i = ranges.begin();
- Ranges::const_iterator ie = ranges.end();
- Ranges::const_iterator j = other.ranges.begin();
- Ranges::const_iterator je = other.ranges.end();
- if (i->first < j->first) {
- i = std::upper_bound(i, ie, *j);
- if (i != ranges.begin()) --i;
- }
- else if (j->first < i->first) {
- j = std::upper_bound(j, je, *i);
- if (j != other.ranges.begin()) --j;
- }
-
- while (i != ie && j != je) {
- if (i->first == j->first) {
- return true;
- }
- else {
- if (i->first > j->first) {
- swap(i, j);
- swap(ie, je);
- }
- assert(i->first < j->first);
- if (i->second > j->first) {
- return true;
- }
- else {
- ++i;
- }
- }
+namespace {
+ // DepthMBBCompare - Comparison predicate that sort first based on the loop
+ // depth of the basic block (the unsigned), and then on the MBB number.
+ struct DepthMBBCompare {
+ typedef std::pair<unsigned, MachineBasicBlock*> DepthMBBPair;
+ bool operator()(const DepthMBBPair &LHS, const DepthMBBPair &RHS) const {
+ if (LHS.first > RHS.first) return true; // Deeper loops first
+ return LHS.first == RHS.first &&
+ LHS.second->getNumber() < RHS.second->getNumber();
}
-
- return false;
+ };
}
-void LiveInterval::addRange(unsigned start, unsigned end)
-{
- assert(start < end && "Invalid range to add!");
- DEBUG(std::cerr << " +[" << start << ',' << end << ")");
- //assert(start < end && "invalid range?");
- Range range = std::make_pair(start, end);
- Ranges::iterator it =
- ranges.insert(std::upper_bound(ranges.begin(), ranges.end(), range),
- range);
-
- it = mergeRangesForward(it);
- it = mergeRangesBackward(it);
+
+void LiveIntervals::CopyCoallesceInMBB(MachineBasicBlock *MBB,
+ std::vector<CopyRec> &TryAgain) {
+ DOUT << ((Value*)MBB->getBasicBlock())->getName() << ":\n";
+
+ for (MachineBasicBlock::iterator MII = MBB->begin(), E = MBB->end();
+ MII != E;) {
+ MachineInstr *Inst = MII++;
+
+ // If this isn't a copy, we can't join intervals.
+ unsigned SrcReg, DstReg;
+ if (!tii_->isMoveInstr(*Inst, SrcReg, DstReg)) continue;
+
+ if (!JoinCopy(Inst, SrcReg, DstReg))
+ TryAgain.push_back(getCopyRec(Inst, SrcReg, DstReg));
+ }
}
-void LiveInterval::join(const LiveInterval& other)
-{
- DEBUG(std::cerr << "\t\tjoining " << *this << " with " << other);
- Ranges::iterator cur = ranges.begin();
- for (Ranges::const_iterator i = other.ranges.begin(),
- e = other.ranges.end(); i != e; ++i) {
- cur = ranges.insert(std::upper_bound(cur, ranges.end(), *i), *i);
- cur = mergeRangesForward(cur);
- cur = mergeRangesBackward(cur);
+void LiveIntervals::joinIntervals() {
+ DOUT << "********** JOINING INTERVALS ***********\n";
+
+ JoinedLIs.resize(getNumIntervals());
+ JoinedLIs.reset();
+
+ std::vector<CopyRec> TryAgainList;
+ const LoopInfo &LI = getAnalysis<LoopInfo>();
+ if (LI.begin() == LI.end()) {
+ // If there are no loops in the function, join intervals in function order.
+ for (MachineFunction::iterator I = mf_->begin(), E = mf_->end();
+ I != E; ++I)
+ CopyCoallesceInMBB(I, TryAgainList);
+ } else {
+ // Otherwise, join intervals in inner loops before other intervals.
+ // Unfortunately we can't just iterate over loop hierarchy here because
+ // there may be more MBB's than BB's. Collect MBB's for sorting.
+ std::vector<std::pair<unsigned, MachineBasicBlock*> > MBBs;
+ for (MachineFunction::iterator I = mf_->begin(), E = mf_->end();
+ I != E; ++I)
+ MBBs.push_back(std::make_pair(LI.getLoopDepth(I->getBasicBlock()), I));
+
+ // Sort by loop depth.
+ std::sort(MBBs.begin(), MBBs.end(), DepthMBBCompare());
+
+ // Finally, join intervals in loop nest order.
+ for (unsigned i = 0, e = MBBs.size(); i != e; ++i)
+ CopyCoallesceInMBB(MBBs[i].second, TryAgainList);
+ }
+
+ // Joining intervals can allow other intervals to be joined. Iteratively join
+ // until we make no progress.
+ bool ProgressMade = true;
+ while (ProgressMade) {
+ ProgressMade = false;
+
+ for (unsigned i = 0, e = TryAgainList.size(); i != e; ++i) {
+ CopyRec &TheCopy = TryAgainList[i];
+ if (TheCopy.MI &&
+ JoinCopy(TheCopy.MI, TheCopy.SrcReg, TheCopy.DstReg)) {
+ TheCopy.MI = 0; // Mark this one as done.
+ ProgressMade = true;
+ }
+ }
+ }
+
+ // Some live range has been lengthened due to colaescing, eliminate the
+ // unnecessary kills.
+ int RegNum = JoinedLIs.find_first();
+ while (RegNum != -1) {
+ unsigned Reg = RegNum + MRegisterInfo::FirstVirtualRegister;
+ unsigned repReg = rep(Reg);
+ LiveInterval &LI = getInterval(repReg);
+ LiveVariables::VarInfo& svi = lv_->getVarInfo(Reg);
+ for (unsigned i = 0, e = svi.Kills.size(); i != e; ++i) {
+ MachineInstr *Kill = svi.Kills[i];
+ // Suppose vr1 = op vr2, x
+ // and vr1 and vr2 are coalesced. vr2 should still be marked kill
+ // unless it is a two-address operand.
+ if (isRemoved(Kill) || hasRegisterDef(Kill, repReg))
+ continue;
+ if (LI.liveAt(getInstructionIndex(Kill) + InstrSlots::NUM))
+ unsetRegisterKill(Kill, repReg);
+ }
+ RegNum = JoinedLIs.find_next(RegNum);
+ }
+
+ DOUT << "*** Register mapping ***\n";
+ for (int i = 0, e = r2rMap_.size(); i != e; ++i)
+ if (r2rMap_[i]) {
+ DOUT << " reg " << i << " -> ";
+ DEBUG(printRegName(r2rMap_[i]));
+ DOUT << "\n";
}
- weight += other.weight;
- ++numJoins;
- DEBUG(std::cerr << ". Result = " << *this << "\n");
}
-LiveInterval::Ranges::iterator LiveInterval::
-mergeRangesForward(Ranges::iterator it)
-{
- Ranges::iterator n;
- while ((n = next(it)) != ranges.end()) {
- if (n->first > it->second)
- break;
- it->second = std::max(it->second, n->second);
- n = ranges.erase(n);
- }
- return it;
+/// Return true if the two specified registers belong to different register
+/// classes. The registers may be either phys or virt regs.
+bool LiveIntervals::differingRegisterClasses(unsigned RegA,
+ unsigned RegB) const {
+
+ // Get the register classes for the first reg.
+ if (MRegisterInfo::isPhysicalRegister(RegA)) {
+ assert(MRegisterInfo::isVirtualRegister(RegB) &&
+ "Shouldn't consider two physregs!");
+ return !mf_->getSSARegMap()->getRegClass(RegB)->contains(RegA);
+ }
+
+ // Compare against the regclass for the second reg.
+ const TargetRegisterClass *RegClass = mf_->getSSARegMap()->getRegClass(RegA);
+ if (MRegisterInfo::isVirtualRegister(RegB))
+ return RegClass != mf_->getSSARegMap()->getRegClass(RegB);
+ else
+ return !RegClass->contains(RegB);
}
-LiveInterval::Ranges::iterator LiveInterval::
-mergeRangesBackward(Ranges::iterator it)
-{
- while (it != ranges.begin()) {
- Ranges::iterator p = prior(it);
- if (it->first > p->second)
- break;
-
- it->first = std::min(it->first, p->first);
- it->second = std::max(it->second, p->second);
- it = ranges.erase(p);
+/// lastRegisterUse - Returns the last use of the specific register between
+/// cycles Start and End. It also returns the use operand by reference. It
+/// returns NULL if there are no uses.
+MachineInstr *
+LiveIntervals::lastRegisterUse(unsigned Reg, unsigned Start, unsigned End,
+ MachineOperand *&MOU) {
+ int e = (End-1) / InstrSlots::NUM * InstrSlots::NUM;
+ int s = Start;
+ while (e >= s) {
+ // Skip deleted instructions
+ MachineInstr *MI = getInstructionFromIndex(e);
+ while ((e - InstrSlots::NUM) >= s && !MI) {
+ e -= InstrSlots::NUM;
+ MI = getInstructionFromIndex(e);
+ }
+ if (e < s || MI == NULL)
+ return NULL;
+
+ for (unsigned i = 0, NumOps = MI->getNumOperands(); i != NumOps; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isUse() && MO.getReg() &&
+ mri_->regsOverlap(rep(MO.getReg()), Reg)) {
+ MOU = &MO;
+ return MI;
+ }
}
- return it;
+ e -= InstrSlots::NUM;
+ }
+
+ return NULL;
}
-std::ostream& llvm::operator<<(std::ostream& os, const LiveInterval& li)
-{
- os << "%reg" << li.reg << ',' << li.weight;
- if (li.empty())
- return os << "EMPTY";
- os << " = ";
- for (LiveInterval::Ranges::const_iterator
- i = li.ranges.begin(), e = li.ranges.end(); i != e; ++i) {
- os << "[" << i->first << "," << i->second << ")";
- }
- return os;
+/// findDefOperand - Returns the MachineOperand that is a def of the specific
+/// register. It returns NULL if the def is not found.
+MachineOperand *LiveIntervals::findDefOperand(MachineInstr *MI, unsigned Reg) {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isDef() &&
+ mri_->regsOverlap(rep(MO.getReg()), Reg))
+ return &MO;
+ }
+ return NULL;
+}
+
+/// unsetRegisterKill - Unset IsKill property of all uses of specific register
+/// of the specific instruction.
+void LiveIntervals::unsetRegisterKill(MachineInstr *MI, unsigned Reg) {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isUse() && MO.isKill() && MO.getReg() &&
+ mri_->regsOverlap(rep(MO.getReg()), Reg))
+ MO.unsetIsKill();
+ }
+}
+
+/// hasRegisterDef - True if the instruction defines the specific register.
+///
+bool LiveIntervals::hasRegisterDef(MachineInstr *MI, unsigned Reg) {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isDef() &&
+ mri_->regsOverlap(rep(MO.getReg()), Reg))
+ return true;
+ }
+ return false;
+}
+
+LiveInterval LiveIntervals::createInterval(unsigned reg) {
+ float Weight = MRegisterInfo::isPhysicalRegister(reg) ?
+ HUGE_VALF : 0.0F;
+ return LiveInterval(reg, Weight);
}
projects / oota-llvm.git / blobdiff