#include "llvm/ADT/STLExtras.h"
#include <algorithm>
#include <cmath>
-#include <iostream>
using namespace llvm;
namespace {
- RegisterAnalysis<LiveIntervals> X("liveintervals", "Live Interval Analysis");
+ RegisterPass<LiveIntervals> X("liveintervals", "Live Interval Analysis");
- Statistic<> numIntervals
+ static Statistic numIntervals
("liveintervals", "Number of original intervals");
- Statistic<> numIntervalsAfter
+ static Statistic numIntervalsAfter
("liveintervals", "Number of intervals after coalescing");
- Statistic<> numJoins
+ static Statistic numJoins
("liveintervals", "Number of interval joins performed");
- Statistic<> numPeep
+ static Statistic numPeep
("liveintervals", "Number of identity moves eliminated after coalescing");
- Statistic<> numFolded
+ static Statistic numFolded
("liveintervals", "Number of loads/stores folded into instructions");
- cl::opt<bool>
+ static cl::opt<bool>
EnableJoining("join-liveintervals",
- cl::desc("Join compatible live intervals"),
+ cl::desc("Coallesce copies (default=true)"),
cl::init(true));
-};
+}
-void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const
-{
+void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<LiveVariables>();
AU.addPreservedID(PHIEliminationID);
AU.addRequiredID(PHIEliminationID);
MachineFunctionPass::getAnalysisUsage(AU);
}
-void LiveIntervals::releaseMemory()
-{
+void LiveIntervals::releaseMemory() {
mi2iMap_.clear();
i2miMap_.clear();
r2iMap_.clear();
"copyRetToReg didn't insert anything!");
}
- // 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;
+ // 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(mi);
- miIndex += InstrSlots::NUM;
+ i2miMap_.push_back(I);
+ MIIndex += InstrSlots::NUM;
}
+ }
// Note intervals due to live-in values.
if (fn.livein_begin() != fn.livein_end()) {
MachineBasicBlock *Entry = fn.begin();
for (MachineFunction::livein_iterator I = fn.livein_begin(),
E = fn.livein_end(); I != E; ++I) {
- handlePhysicalRegisterDef(Entry, Entry->begin(),
- getOrCreateInterval(I->first), 0, 0, true);
+ handlePhysicalRegisterDef(Entry, Entry->begin(), 0,
+ getOrCreateInterval(I->first), 0);
for (const unsigned* AS = mri_->getAliasSet(I->first); *AS; ++AS)
- handlePhysicalRegisterDef(Entry, Entry->begin(),
- getOrCreateInterval(*AS), 0, 0, true);
+ handlePhysicalRegisterDef(Entry, Entry->begin(), 0,
+ getOrCreateInterval(*AS), 0);
}
}
numIntervals += getNumIntervals();
- DEBUG(std::cerr << "********** INTERVALS **********\n";
- for (iterator I = begin(), E = end(); I != E; ++I) {
- I->second.print(std::cerr, mri_);
- std::cerr << "\n";
- });
+ DOUT << "********** INTERVALS **********\n";
+ for (iterator I = begin(), E = end(); I != E; ++I) {
+ I->second.print(DOUT, mri_);
+ DOUT << "\n";
+ }
- // join intervals if requested
+ // 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>();
+ // 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) {
if (tii_->isMoveInstr(*mii, srcReg, dstReg) &&
(RegRep = rep(srcReg)) == rep(dstReg)) {
// remove from def list
- LiveInterval &interval = getOrCreateInterval(RegRep);
- // 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);
- }
+ getOrCreateInterval(RegRep);
+ RemoveMachineInstrFromMaps(mii);
mii = mbbi->erase(mii);
++numPeep;
}
else {
- for (unsigned i = 0; i < mii->getNumOperands(); ++i) {
- const MachineOperand& mop = mii->getOperand(i);
+ 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
}
}
+
for (iterator I = begin(), E = end(); I != E; ++I) {
- LiveInterval &li = I->second;
- if (MRegisterInfo::isVirtualRegister(li.reg))
- // If the live interval legnth is essentially zero, i.e. in every live
+ 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 = float(HUGE_VAL);
+ 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;
+ }
}
DEBUG(dump());
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(std::cerr, mri_);
- std::cerr << "\n";
+ I->second.print(DOUT, mri_);
+ DOUT << "\n";
}
O << "********** MACHINEINSTRS **********\n";
}
}
+/// 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) {
// since this is called after the analysis is done we don't know if
std::vector<LiveInterval*> added;
- assert(li.weight != HUGE_VAL &&
+ assert(li.weight != HUGE_VALF &&
"attempt to spill already spilled interval!");
- DEBUG(std::cerr << "\t\t\t\tadding intervals for spills for interval: "
- << li << '\n');
+ DOUT << "\t\t\t\tadding intervals for spills for interval: ";
+ li.print(DOUT, mri_);
+ DOUT << '\n';
const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(li.reg);
MachineInstr *MI = getInstructionFromIndex(index);
- // NewRegLiveIn - This instruction might have multiple uses of the spilled
- // register. In this case, for the first use, keep track of the new vreg
- // that we reload it into. If we see a second use, reuse this vreg
- // instead of creating live ranges for two reloads.
- unsigned NewRegLiveIn = 0;
-
- for_operand:
+ RestartInstruction:
for (unsigned i = 0; i != MI->getNumOperands(); ++i) {
MachineOperand& mop = MI->getOperand(i);
if (mop.isRegister() && mop.getReg() == li.reg) {
- if (NewRegLiveIn && mop.isUse()) {
- // We already emitted a reload of this value, reuse it for
- // subsequent operands.
- MI->getOperand(i).setReg(NewRegLiveIn);
- DEBUG(std::cerr << "\t\t\t\treused reload into reg" << NewRegLiveIn
- << " for operand #" << i << '\n');
- } else if (MachineInstr* fmi = mri_->foldMemoryOperand(MI, i, slot)) {
+ if (MachineInstr *fmi = mri_->foldMemoryOperand(MI, i, slot)) {
// Attempt to fold the memory reference into the instruction. If we
// can do this, we don't need to insert spill code.
if (lv_)
++numFolded;
// Folding the load/store can completely change the instruction in
// unpredictable ways, rescan it from the beginning.
- goto for_operand;
+ goto RestartInstruction;
} 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.
+ // 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.
//
- // 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));
+ // 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
- NewRegLiveIn = mf_->getSSARegMap()->createVirtualRegister(rc);
- MI->getOperand(i).setReg(NewRegLiveIn);
vrm.grow();
- vrm.assignVirt2StackSlot(NewRegLiveIn, slot);
- LiveInterval& nI = getOrCreateInterval(NewRegLiveIn);
+ vrm.assignVirt2StackSlot(NewVReg, slot);
+ LiveInterval &nI = getOrCreateInterval(NewVReg);
assert(nI.empty());
// the spill weight is now infinity as it
// cannot be spilled again
- nI.weight = float(HUGE_VAL);
- LiveRange LR(start, end, nI.getNextValue());
- DEBUG(std::cerr << " +" << LR);
- nI.addRange(LR);
+ 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(NewRegLiveIn, MI);
-
- // If this is a live in, reuse it for subsequent live-ins. If it's
- // a def, we can't do this.
- if (!mop.isUse()) NewRegLiveIn = 0;
+ lv_->addVirtualRegisterKilled(NewVReg, MI);
- DEBUG(std::cerr << "\t\t\t\tadded new interval: " << nI << '\n');
+ DOUT << "\t\t\t\tadded new interval: ";
+ nI.print(DOUT, mri_);
+ DOUT << '\n';
}
}
}
return added;
}
-void LiveIntervals::printRegName(unsigned reg) const
-{
+void LiveIntervals::printRegName(unsigned reg) const {
if (MRegisterInfo::isPhysicalRegister(reg))
- std::cerr << mri_->getName(reg);
+ cerr << mri_->getName(reg);
else
- std::cerr << "%reg" << reg;
+ 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));
+ 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
// time we see a vreg.
if (interval.empty()) {
// Get the Idx of the defining instructions.
- unsigned defIndex = getDefIndex(getInstructionIndex(mi));
-
- unsigned ValNum = interval.getNextValue();
+ 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.
"Shouldn't be alive across any blocks!");
LiveRange LR(defIndex, killIdx, ValNum);
interval.addRange(LR);
- DEBUG(std::cerr << " +" << LR << "\n");
+ DOUT << " +" << LR << "\n";
return;
}
}
LiveRange NewLR(defIndex,
getInstructionIndex(&mbb->back()) + InstrSlots::NUM,
ValNum);
- DEBUG(std::cerr << " +" << NewLR);
+ DOUT << " +" << NewLR;
interval.addRange(NewLR);
// Iterate over all of the blocks that the variable is completely
// 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(getInstructionIndex(&mbb->front()),
- getInstructionIndex(&mbb->back()) + InstrSlots::NUM,
+ MachineBasicBlock *MBB = mf_->getBlockNumbered(i);
+ if (!MBB->empty()) {
+ LiveRange LR(getMBBStartIdx(i),
+ getInstructionIndex(&MBB->back()) + InstrSlots::NUM,
ValNum);
interval.addRange(LR);
- DEBUG(std::cerr << " +" << LR);
+ DOUT << " +" << LR;
}
}
}
// 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(getInstructionIndex(Kill->getParent()->begin()),
+ LiveRange LR(getMBBStartIdx(Kill->getParent()),
getUseIndex(getInstructionIndex(Kill))+1,
ValNum);
interval.addRange(LR);
- DEBUG(std::cerr << " +" << LR);
+ DOUT << " +" << LR;
}
} else {
// 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 the first
- // operand, and is a def-and-use.
- if (mi->getOperand(0).isRegister() &&
- mi->getOperand(0).getReg() == interval.reg &&
- mi->getOperand(0).isDef() && mi->getOperand(0).isUse()) {
+ // 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(getInstructionIndex(mi));
+ unsigned RedefIndex = getDefIndex(MIIdx);
// Delete the initial value, which should be short and continuous,
- // becuase the 2-addr copy must be in the same MBB as the redef.
+ // because the 2-addr copy must be in the same MBB as the redef.
interval.removeRange(DefIndex, RedefIndex);
- LiveRange LR(DefIndex, RedefIndex, interval.getNextValue());
- DEBUG(std::cerr << " replace range with " << LR);
+ // 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
if (lv_->RegisterDefIsDead(mi, interval.reg))
interval.addRange(LiveRange(RedefIndex, RedefIndex+1, 0));
- DEBUG(std::cerr << "RESULT: " << interval);
+ DOUT << "RESULT: ";
+ interval.print(DOUT, mri_);
} else {
// Otherwise, this must be because of phi elimination. If this is the
// Remove the old range that we now know has an incorrect number.
MachineInstr *Killer = vi.Kills[0];
- unsigned Start = getInstructionIndex(Killer->getParent()->begin());
+ unsigned Start = getMBBStartIdx(Killer->getParent());
unsigned End = getUseIndex(getInstructionIndex(Killer))+1;
- DEBUG(std::cerr << "Removing [" << Start << "," << End << "] from: "
- << interval << "\n");
+ DOUT << "Removing [" << Start << "," << End << "] from: ";
+ interval.print(DOUT, mri_); DOUT << "\n";
interval.removeRange(Start, End);
- DEBUG(std::cerr << "RESULT: " << interval);
+ DOUT << "RESULT: "; interval.print(DOUT, mri_);
- // Replace the interval with one of a NEW value number.
- LiveRange LR(Start, End, interval.getNextValue());
- DEBUG(std::cerr << " replace range with " << LR);
+ // 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);
- DEBUG(std::cerr << "RESULT: " << interval);
+ 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(getInstructionIndex(mi));
+ 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,
- interval.getNextValue());
+ getInstructionIndex(&mbb->back()) + InstrSlots::NUM, ValNum);
interval.addRange(LR);
- DEBUG(std::cerr << " +" << LR);
+ DOUT << " +" << LR;
}
}
- DEBUG(std::cerr << '\n');
+ DOUT << '\n';
}
void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock *MBB,
MachineBasicBlock::iterator mi,
- LiveInterval& interval,
- unsigned SrcReg, unsigned DestReg,
- bool isLiveIn)
-{
+ 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.
- DEBUG(std::cerr << "\t\tregister: "; printRegName(interval.reg));
- typedef LiveVariables::killed_iterator KillIter;
+ DOUT << "\t\tregister: "; DEBUG(printRegName(interval.reg));
- unsigned baseIndex = getInstructionIndex(mi);
+ unsigned baseIndex = MIIdx;
unsigned start = getDefIndex(baseIndex);
unsigned end = start;
// the instruction defining it. Hence its interval is:
// [defSlot(def), defSlot(def)+1)
if (lv_->RegisterDefIsDead(mi, interval.reg)) {
- DEBUG(std::cerr << " dead");
+ DOUT << " dead";
end = getDefIndex(start) + 1;
goto exit;
}
while (++mi != MBB->end()) {
baseIndex += InstrSlots::NUM;
if (lv_->KillsRegister(mi, interval.reg)) {
- DEBUG(std::cerr << " killed");
+ 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;
}
}
// 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(isLiveIn && "physreg was not killed in defining block!");
+ 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?");
- // Finally, if this is defining a new range for the physical register, and if
- // that physreg is just a copy from a vreg, and if THAT vreg was a copy from
- // the physreg, then the new fragment has the same value as the one copied
- // into the vreg.
- if (interval.reg == DestReg && !interval.empty() &&
- MRegisterInfo::isVirtualRegister(SrcReg)) {
-
- // Get the live interval for the vreg, see if it is defined by a copy.
- LiveInterval &SrcInterval = getOrCreateInterval(SrcReg);
-
- if (SrcInterval.containsOneValue()) {
- assert(!SrcInterval.empty() && "Can't contain a value and be empty!");
-
- // Get the first index of the first range. Though the interval may have
- // multiple liveranges in it, we only check the first.
- unsigned StartIdx = SrcInterval.begin()->start;
- MachineInstr *SrcDefMI = getInstructionFromIndex(StartIdx);
-
- // Check to see if the vreg was defined by a copy instruction, and that
- // the source was this physreg.
- unsigned VRegSrcSrc, VRegSrcDest;
- if (tii_->isMoveInstr(*SrcDefMI, VRegSrcSrc, VRegSrcDest) &&
- SrcReg == VRegSrcDest && VRegSrcSrc == DestReg) {
- // Okay, now we know that the vreg was defined by a copy from this
- // physreg. Find the value number being copied and use it as the value
- // for this range.
- const LiveRange *DefRange = interval.getLiveRangeContaining(StartIdx-1);
- if (DefRange) {
- LiveRange LR(start, end, DefRange->ValId);
- interval.addRange(LR);
- DEBUG(std::cerr << " +" << LR << '\n');
- return;
- }
- }
- }
- }
-
-
- LiveRange LR(start, end, interval.getNextValue());
+ LiveRange LR(start, end, interval.getNextValue(SrcReg != 0 ? start : ~0U,
+ SrcReg));
interval.addRange(LR);
- DEBUG(std::cerr << " +" << LR << '\n');
+ DOUT << " +" << LR << '\n';
}
void LiveIntervals::handleRegisterDef(MachineBasicBlock *MBB,
MachineBasicBlock::iterator MI,
+ unsigned MIIdx,
unsigned reg) {
if (MRegisterInfo::isVirtualRegister(reg))
- handleVirtualRegisterDef(MBB, MI, getOrCreateInterval(reg));
+ handleVirtualRegisterDef(MBB, MI, MIIdx, getOrCreateInterval(reg));
else if (allocatableRegs_[reg]) {
- unsigned SrcReg = 0, DestReg = 0;
- if (!tii_->isMoveInstr(*MI, SrcReg, DestReg))
- SrcReg = DestReg = 0;
-
- handlePhysicalRegisterDef(MBB, MI, getOrCreateInterval(reg),
- SrcReg, DestReg);
+ 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, getOrCreateInterval(*AS),
- SrcReg, DestReg);
+ handlePhysicalRegisterDef(MBB, MI, MIIdx, getOrCreateInterval(*AS), 0);
}
}
/// 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');
+void LiveIntervals::computeIntervals() {
+ DOUT << "********** COMPUTING LIVE INTERVALS **********\n"
+ << "********** Function: "
+ << ((Value*)mf_->getFunction())->getName() << '\n';
bool IgnoreFirstInstr = mf_->livein_begin() != mf_->livein_end();
- for (MachineFunction::iterator I = mf_->begin(), E = mf_->end();
- I != E; ++I) {
- MachineBasicBlock* mbb = I;
- DEBUG(std::cerr << ((Value*)mbb->getBasicBlock())->getName() << ":\n");
-
- MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
- if (IgnoreFirstInstr) { ++mi; IgnoreFirstInstr = false; }
- for (; mi != miEnd; ++mi) {
- const TargetInstrDescriptor& tid =
- tm_->getInstrInfo()->get(mi->getOpcode());
- DEBUG(std::cerr << getInstructionIndex(mi) << "\t" << *mi);
-
- // 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);
+ // 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 (IgnoreFirstInstr) {
+ ++MI;
+ IgnoreFirstInstr = false;
+ MIIndex += InstrSlots::NUM;
+ }
+
+ 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 (mop.isRegister() && mop.getReg() && mop.isDef())
- handleRegisterDef(mbb, mi, mop.getReg());
+ if (MO.isRegister() && MO.getReg() && MO.isDef())
+ handleRegisterDef(MBB, MI, MIIndex, MO.getReg());
}
+
+ MIIndex += InstrSlots::NUM;
}
}
}
-/// IntA is defined as a copy from IntB and we know it only has one value
-/// number. If all of the places that IntA and IntB overlap are defined by
-/// copies from IntA to IntB, we know that these two ranges can really be
-/// merged if we adjust the value numbers. If it is safe, adjust the value
-/// numbers and return true, allowing coalescing to occur.
-bool LiveIntervals::
-AdjustIfAllOverlappingRangesAreCopiesFrom(LiveInterval &IntA,
- LiveInterval &IntB,
- unsigned CopyIdx) {
- std::vector<LiveRange*> Ranges;
- IntA.getOverlapingRanges(IntB, CopyIdx, Ranges);
-
- assert(!Ranges.empty() && "Why didn't we do a simple join of this?");
-
- unsigned IntBRep = rep(IntB.reg);
-
- // Check to see if all of the overlaps (entries in Ranges) are defined by a
- // copy from IntA. If not, exit.
- for (unsigned i = 0, e = Ranges.size(); i != e; ++i) {
- unsigned Idx = Ranges[i]->start;
- MachineInstr *MI = getInstructionFromIndex(Idx);
- unsigned SrcReg, DestReg;
- if (!tii_->isMoveInstr(*MI, SrcReg, DestReg)) return false;
+/// 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 this copy isn't actually defining this range, it must be a live
- // range spanning basic blocks or something.
- if (rep(DestReg) != rep(IntA.reg)) return false;
+ // If the value number is not defined by a copy instruction, ignore it.
- // Check to see if this is coming from IntB. If not, bail out.
- if (rep(SrcReg) != IntBRep) return false;
+ // 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, we can change this one. Get the IntB value number that IntA is
- // copied from.
- unsigned ActualValNo = IntA.getLiveRangeContaining(CopyIdx-1)->ValId;
-
- // Change all of the value numbers to the same as what we IntA is copied from.
- for (unsigned i = 0, e = Ranges.size(); i != e; ++i)
- Ranges[i]->ValId = ActualValNo;
+ // 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";
+ // Finally, delete the copy instruction.
+ RemoveMachineInstrFromMaps(CopyMI);
+ CopyMI->eraseFromParent();
+ ++numPeep;
return true;
}
-void LiveIntervals::joinIntervalsInMachineBB(MachineBasicBlock *MBB) {
- DEBUG(std::cerr << ((Value*)MBB->getBasicBlock())->getName() << ":\n");
-
- for (MachineBasicBlock::iterator mi = MBB->begin(), mie = MBB->end();
- mi != mie; ++mi) {
- DEBUG(std::cerr << getInstructionIndex(mi) << '\t' << *mi);
- // we only join virtual registers with allocatable
- // physical registers since we do not have liveness information
- // on not allocatable physical registers
- unsigned SrcReg, DestReg;
- if (tii_->isMoveInstr(*mi, SrcReg, DestReg) &&
- (MRegisterInfo::isVirtualRegister(SrcReg) || allocatableRegs_[SrcReg])&&
- (MRegisterInfo::isVirtualRegister(DestReg)||allocatableRegs_[DestReg])){
-
- // Get representative registers.
- SrcReg = rep(SrcReg);
- DestReg = rep(DestReg);
+/// 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.
+ SrcReg = rep(SrcReg);
+ DstReg = rep(DstReg);
+
+ // If they are already joined we continue.
+ if (SrcReg == DstReg) {
+ DOUT << "\tCopy already coallesced.\n";
+ return true; // Not coallescable.
+ }
+
+ // If they are both physical registers, we cannot join them.
+ if (MRegisterInfo::isPhysicalRegister(SrcReg) &&
+ MRegisterInfo::isPhysicalRegister(DstReg)) {
+ DOUT << "\tCan not coallesce physregs.\n";
+ return true; // Not coallescable.
+ }
+
+ // We only join virtual registers with allocatable physical registers.
+ if (MRegisterInfo::isPhysicalRegister(SrcReg) && !allocatableRegs_[SrcReg]){
+ DOUT << "\tSrc reg is unallocatable physreg.\n";
+ return true; // Not coallescable.
+ }
+ if (MRegisterInfo::isPhysicalRegister(DstReg) && !allocatableRegs_[DstReg]){
+ 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(SrcReg, DstReg)) {
+ DOUT << "\tSrc/Dest are different register classes.\n";
+ return true; // Not coallescable.
+ }
+
+ LiveInterval &SrcInt = getInterval(SrcReg);
+ LiveInterval &DestInt = getInterval(DstReg);
+ assert(SrcInt.reg == SrcReg && DestInt.reg == DstReg &&
+ "Register mapping is horribly broken!");
+
+ DOUT << "\t\tInspecting "; SrcInt.print(DOUT, mri_);
+ DOUT << " and "; DestInt.print(DOUT, mri_);
+ DOUT << ": ";
+
+ // 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)) {
+ // Coallescing failed.
+
+ // If we can eliminate the copy without merging the live ranges, do so now.
+ if (AdjustCopiesBackFrom(SrcInt, DestInt, CopyMI))
+ return true;
- // If they are already joined we continue.
- if (SrcReg == DestReg)
- continue;
+ // Otherwise, we are unable to join the intervals.
+ DOUT << "Interference!\n";
+ return false;
+ }
- // If they are both physical registers, we cannot join them.
- if (MRegisterInfo::isPhysicalRegister(SrcReg) &&
- MRegisterInfo::isPhysicalRegister(DestReg))
- continue;
+ bool Swapped = SrcReg == DestInt.reg;
+ if (Swapped)
+ std::swap(SrcReg, DstReg);
+ assert(MRegisterInfo::isVirtualRegister(SrcReg) &&
+ "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(DstReg)) {
+ for (const unsigned *AS = mri_->getAliasSet(DstReg); *AS; ++AS)
+ getInterval(*AS).MergeInClobberRanges(SrcInt);
+ }
- // If they are not of compatible register classes, we cannot join them.
- bool Swap = false;
- if (!compatibleRegisterClasses(SrcReg, DestReg, Swap)) {
- DEBUG(std::cerr << "Register classes aren't compatible!\n");
- continue;
- }
+ DOUT << "\n\t\tJoined. Result = "; DestInt.print(DOUT, mri_);
+ DOUT << "\n";
+
+ // 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);
+ r2iMap_.erase(SrcReg);
+ r2rMap_[SrcReg] = DstReg;
+
+ // Finally, delete the copy instruction.
+ RemoveMachineInstrFromMaps(CopyMI);
+ CopyMI->eraseFromParent();
+ ++numPeep;
+ ++numJoins;
+ return true;
+}
- LiveInterval &SrcInt = getInterval(SrcReg);
- LiveInterval &DestInt = getInterval(DestReg);
- assert(SrcInt.reg == SrcReg && DestInt.reg == DestReg &&
- "Register mapping is horribly broken!");
+/// 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;
+ }
- DEBUG(std::cerr << "\t\tInspecting " << SrcInt << " and " << DestInt
- << ": ");
+ // 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;
+}
- // If two intervals contain a single value and are joined by a copy, it
- // does not matter if the intervals overlap, they can always be joined.
- bool Joinable = SrcInt.containsOneValue() && DestInt.containsOneValue();
+static bool InVector(unsigned Val, const SmallVector<unsigned, 8> &V) {
+ return std::find(V.begin(), V.end(), Val) != V.end();
+}
- unsigned MIDefIdx = getDefIndex(getInstructionIndex(mi));
+/// 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);
+ }
- // If the intervals think that this is joinable, do so now.
- if (!Joinable && DestInt.joinable(SrcInt, MIDefIdx))
- Joinable = true;
-
- // If DestInt is actually a copy from SrcInt (which we know) that is used
- // to define another value of SrcInt, we can change the other range of
- // SrcInt to be the value of the range that defines DestInt, allowing a
- // coalesce.
- if (!Joinable && DestInt.containsOneValue() &&
- AdjustIfAllOverlappingRangesAreCopiesFrom(SrcInt, DestInt, MIDefIdx))
- Joinable = true;
+ // 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 (!Joinable || overlapsAliases(&SrcInt, &DestInt)) {
- DEBUG(std::cerr << "Interference!\n");
+ 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 {
- DestInt.join(SrcInt, MIDefIdx);
- DEBUG(std::cerr << "Joined. Result = " << DestInt << "\n");
+ // 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;
+}
- if (!Swap && !MRegisterInfo::isPhysicalRegister(SrcReg)) {
- r2iMap_.erase(SrcReg);
- r2rMap_[SrcReg] = DestReg;
+/// 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 merge the data structures the other way so we don't lose
- // the physreg information.
- r2rMap_[DestReg] = SrcReg;
- DestInt.reg = SrcReg;
- SrcInt.swap(DestInt);
- r2iMap_.erase(DestReg);
+ // Otherwise, use the specified value #.
+ LHSValNoAssignments[VN] = RHSValID;
+ if (VN != (unsigned)RHSValID)
+ ValueNumberInfo[VN].first = ~1U;
+ else
+ ValueNumberInfo[VN] = RHSValNoInfo;
}
- ++numJoins;
+ } 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;
+ }
+ }
+
+ // 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;
}
+
namespace {
// DepthMBBCompare - Comparison predicate that sort first based on the loop
// depth of the basic block (the unsigned), and then on the MBB number.
};
}
+
+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 LiveIntervals::joinIntervals() {
- DEBUG(std::cerr << "********** JOINING INTERVALS ***********\n");
+ DOUT << "********** JOINING INTERVALS ***********\n";
+ 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)
- joinIntervalsInMachineBB(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
// Finally, join intervals in loop nest order.
for (unsigned i = 0, e = MBBs.size(); i != e; ++i)
- joinIntervalsInMachineBB(MBBs[i].second);
+ CopyCoallesceInMBB(MBBs[i].second, TryAgainList);
}
-
- DEBUG(std::cerr << "*** Register mapping ***\n");
- DEBUG(for (int i = 0, e = r2rMap_.size(); i != e; ++i)
- if (r2rMap_[i])
- std::cerr << " reg " << i << " -> reg " << r2rMap_[i] << "\n");
+
+ // 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;
+ }
+ }
+ }
+
+ 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";
+ }
}
-/// Return true if the two specified registers belong to same or compatible
-/// register classes. The registers may be either phys or virt regs.
-bool LiveIntervals::compatibleRegisterClasses(unsigned RegA, unsigned RegB,
- bool &Swap) const {
+/// 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);
+ return !mf_->getSSARegMap()->getRegClass(RegB)->contains(RegA);
}
// Compare against the regclass for the second reg.
- const TargetRegisterClass *RegClassA = mf_->getSSARegMap()->getRegClass(RegA);
- if (MRegisterInfo::isVirtualRegister(RegB)) {
- const TargetRegisterClass *RegClassB=mf_->getSSARegMap()->getRegClass(RegB);
- if (RegClassA == RegClassB)
- return true;
- else {
- if (RegClassB->hasSubRegClass(RegClassA)) {
- Swap = true;
- return true;
- }
- return RegClassA->hasSubRegClass(RegClassB);
- }
- } else
- return RegClassA->contains(RegB);
-}
-
-bool LiveIntervals::overlapsAliases(const LiveInterval *LHS,
- const LiveInterval *RHS) const {
- if (!MRegisterInfo::isPhysicalRegister(LHS->reg)) {
- if (!MRegisterInfo::isPhysicalRegister(RHS->reg))
- return false; // vreg-vreg merge has no aliases!
- std::swap(LHS, RHS);
- }
-
- assert(MRegisterInfo::isPhysicalRegister(LHS->reg) &&
- MRegisterInfo::isVirtualRegister(RHS->reg) &&
- "first interval must describe a physical register");
-
- for (const unsigned *AS = mri_->getAliasSet(LHS->reg); *AS; ++AS)
- if (RHS->overlaps(getInterval(*AS)))
- return true;
-
- return false;
+ const TargetRegisterClass *RegClass = mf_->getSSARegMap()->getRegClass(RegA);
+ if (MRegisterInfo::isVirtualRegister(RegB))
+ return RegClass != mf_->getSSARegMap()->getRegClass(RegB);
+ else
+ return !RegClass->contains(RegB);
}
LiveInterval LiveIntervals::createInterval(unsigned reg) {
float Weight = MRegisterInfo::isPhysicalRegister(reg) ?
- (float)HUGE_VAL :0.0F;
+ HUGE_VALF : 0.0F;
return LiveInterval(reg, Weight);
}
projects / oota-llvm.git / blobdiff