#include "llvm/CodeGen/LiveVariables.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Config/alloca.h"
#include <algorithm>
using namespace llvm;
char LiveVariables::ID = 0;
static RegisterPass<LiveVariables> X("livevars", "Live Variable Analysis");
void LiveVariables::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredID(UnreachableMachineBlockElimID);
AU.setPreservesAll();
}
void LiveVariables::VarInfo::dump() const {
cerr << " Alive in blocks: ";
for (int i = AliveBlocks.find_first(); i != -1; i = AliveBlocks.find_next(i))
cerr << i << ", ";
cerr << " Used in blocks: ";
for (int i = UsedBlocks.find_first(); i != -1; i = UsedBlocks.find_next(i))
cerr << i << ", ";
cerr << "\n Killed by:";
if (Kills.empty())
cerr << " No instructions.\n";
else {
for (unsigned i = 0, e = Kills.size(); i != e; ++i)
cerr << "\n #" << i << ": " << *Kills[i];
cerr << "\n";
}
}
LiveVariables::VarInfo &LiveVariables::getVarInfo(unsigned RegIdx) {
assert(TargetRegisterInfo::isVirtualRegister(RegIdx) &&
"getVarInfo: not a virtual register!");
RegIdx -= TargetRegisterInfo::FirstVirtualRegister;
if (RegIdx >= VirtRegInfo.size()) {
if (RegIdx >= 2*VirtRegInfo.size())
VirtRegInfo.resize(RegIdx*2);
else
VirtRegInfo.resize(2*VirtRegInfo.size());
}
VarInfo &VI = VirtRegInfo[RegIdx];
VI.AliveBlocks.resize(MF->getNumBlockIDs());
VI.UsedBlocks.resize(MF->getNumBlockIDs());
return VI;
}
void LiveVariables::MarkVirtRegAliveInBlock(VarInfo& VRInfo,
MachineBasicBlock *DefBlock,
MachineBasicBlock *MBB,
std::vector<MachineBasicBlock*> &WorkList) {
unsigned BBNum = MBB->getNumber();
for (unsigned i = 0, e = VRInfo.Kills.size(); i != e; ++i)
if (VRInfo.Kills[i]->getParent() == MBB) {
VRInfo.Kills.erase(VRInfo.Kills.begin()+i); break;
}
if (MBB == DefBlock) return;
if (VRInfo.AliveBlocks[BBNum])
return;
VRInfo.AliveBlocks[BBNum] = true;
for (MachineBasicBlock::const_pred_reverse_iterator PI = MBB->pred_rbegin(),
E = MBB->pred_rend(); PI != E; ++PI)
WorkList.push_back(*PI);
}
void LiveVariables::MarkVirtRegAliveInBlock(VarInfo &VRInfo,
MachineBasicBlock *DefBlock,
MachineBasicBlock *MBB) {
std::vector<MachineBasicBlock*> WorkList;
MarkVirtRegAliveInBlock(VRInfo, DefBlock, MBB, WorkList);
while (!WorkList.empty()) {
MachineBasicBlock *Pred = WorkList.back();
WorkList.pop_back();
MarkVirtRegAliveInBlock(VRInfo, DefBlock, Pred, WorkList);
}
}
void LiveVariables::HandleVirtRegUse(unsigned reg, MachineBasicBlock *MBB,
MachineInstr *MI) {
assert(MRI->getVRegDef(reg) && "Register use before def!");
unsigned BBNum = MBB->getNumber();
VarInfo& VRInfo = getVarInfo(reg);
VRInfo.UsedBlocks[BBNum] = true;
VRInfo.NumUses++;
if (!VRInfo.Kills.empty() && VRInfo.Kills.back()->getParent() == MBB) {
VRInfo.Kills.back() = MI;
return;
}
#ifndef NDEBUG
for (unsigned i = 0, e = VRInfo.Kills.size(); i != e; ++i)
assert(VRInfo.Kills[i]->getParent() != MBB && "entry should be at end!");
#endif
if (MBB == MRI->getVRegDef(reg)->getParent()) return;
if (!VRInfo.AliveBlocks[BBNum])
VRInfo.Kills.push_back(MI);
for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(),
E = MBB->pred_end(); PI != E; ++PI)
MarkVirtRegAliveInBlock(VRInfo, MRI->getVRegDef(reg)->getParent(), *PI);
}
void LiveVariables::HandleVirtRegDef(unsigned Reg, MachineInstr *MI) {
VarInfo &VRInfo = getVarInfo(Reg);
if (VRInfo.AliveBlocks.none())
VRInfo.Kills.push_back(MI);
}
MachineInstr *LiveVariables::FindLastPartialDef(unsigned Reg,
unsigned &PartDefReg) {
unsigned LastDefReg = 0;
unsigned LastDefDist = 0;
MachineInstr *LastDef = NULL;
for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
MachineInstr *Def = PhysRegDef[SubReg];
if (!Def)
continue;
unsigned Dist = DistanceMap[Def];
if (Dist > LastDefDist) {
LastDefReg = SubReg;
LastDef = Def;
LastDefDist = Dist;
}
}
PartDefReg = LastDefReg;
return LastDef;
}
void LiveVariables::HandlePhysRegUse(unsigned Reg, MachineInstr *MI) {
if (!PhysRegDef[Reg] && !PhysRegUse[Reg]) {
unsigned PartDefReg = 0;
MachineInstr *LastPartialDef = FindLastPartialDef(Reg, PartDefReg);
if (LastPartialDef) {
LastPartialDef->addOperand(MachineOperand::CreateReg(Reg, true,
true));
PhysRegDef[Reg] = LastPartialDef;
SmallSet<unsigned, 8> Processed;
for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
if (Processed.count(SubReg))
continue;
if (SubReg == PartDefReg || TRI->isSubRegister(PartDefReg, SubReg))
continue;
LastPartialDef->addOperand(MachineOperand::CreateReg(SubReg,
false,
true));
PhysRegDef[SubReg] = LastPartialDef;
for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
Processed.insert(*SS);
}
}
}
if (!PhysRegUse[Reg]) {
MachineInstr *Def = PhysRegDef[Reg];
if (Def && !Def->modifiesRegister(Reg))
Def->addOperand(MachineOperand::CreateReg(Reg,
true ,
true ));
}
PhysRegUse[Reg] = MI;
for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs)
PhysRegUse[SubReg] = MI;
}
bool LiveVariables::hasRegisterUseBelow(unsigned Reg,
MachineBasicBlock::iterator I,
MachineBasicBlock *MBB) {
if (I == MBB->end())
return false;
bool hasDistInfo = true;
unsigned CurDist = DistanceMap[I];
SmallVector<MachineInstr*, 4> Uses;
SmallVector<MachineInstr*, 4> Defs;
for (MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(Reg),
RE = MRI->reg_end(); RI != RE; ++RI) {
MachineOperand &UDO = RI.getOperand();
MachineInstr *UDMI = &*RI;
if (UDMI->getParent() != MBB)
continue;
DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UDMI);
bool isBelow = false;
if (DI == DistanceMap.end()) {
isBelow = true;
hasDistInfo = false;
} else if (DI->second > CurDist)
isBelow = true;
if (isBelow) {
if (UDO.isUse())
Uses.push_back(UDMI);
if (UDO.isDef())
Defs.push_back(UDMI);
}
}
if (Uses.empty())
return false;
else if (!Uses.empty() && Defs.empty())
return true;
if (!hasDistInfo) {
++I;
++CurDist;
for (MachineBasicBlock::iterator E = MBB->end(); I != E; ++I, ++CurDist)
DistanceMap.insert(std::make_pair(I, CurDist));
}
unsigned EarliestUse = DistanceMap[Uses[0]];
for (unsigned i = 1, e = Uses.size(); i != e; ++i) {
unsigned Dist = DistanceMap[Uses[i]];
if (Dist < EarliestUse)
EarliestUse = Dist;
}
for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
unsigned Dist = DistanceMap[Defs[i]];
if (Dist < EarliestUse)
return false;
}
return true;
}
bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) {
if (!PhysRegUse[Reg] && !PhysRegDef[Reg])
return false;
MachineInstr *LastRefOrPartRef = PhysRegUse[Reg]
? PhysRegUse[Reg] : PhysRegDef[Reg];
unsigned LastRefOrPartRefDist = DistanceMap[LastRefOrPartRef];
SmallSet<unsigned, 8> PartUses;
for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
if (MachineInstr *Use = PhysRegUse[SubReg]) {
PartUses.insert(SubReg);
for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
PartUses.insert(*SS);
unsigned Dist = DistanceMap[Use];
if (Dist > LastRefOrPartRefDist) {
LastRefOrPartRefDist = Dist;
LastRefOrPartRef = Use;
}
}
}
if (LastRefOrPartRef == PhysRegDef[Reg] && LastRefOrPartRef != MI)
LastRefOrPartRef->addRegisterDead(Reg, TRI, true);
else
LastRefOrPartRef->addRegisterKilled(Reg, TRI, true);
return true;
}
void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI) {
SmallSet<unsigned, 32> Live;
if (PhysRegDef[Reg] || PhysRegUse[Reg]) {
Live.insert(Reg);
for (const unsigned *SS = TRI->getSubRegisters(Reg); *SS; ++SS)
Live.insert(*SS);
} else {
for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
if (PhysRegDef[SubReg] || PhysRegUse[SubReg]) {
Live.insert(SubReg);
for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
Live.insert(*SS);
}
}
}
if (!HandlePhysRegKill(Reg, MI)) {
for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
if (!Live.count(SubReg))
continue;
if (HandlePhysRegKill(SubReg, MI)) {
Live.erase(SubReg);
for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
Live.erase(*SS);
}
}
assert(Live.empty() && "Not all defined registers are killed / dead?");
}
if (MI) {
SmallSet<unsigned, 8> Processed;
for (const unsigned *SuperRegs = TRI->getSuperRegisters(Reg);
unsigned SuperReg = *SuperRegs; ++SuperRegs) {
if (Processed.count(SuperReg))
continue;
MachineInstr *LastRef = PhysRegUse[SuperReg]
? PhysRegUse[SuperReg] : PhysRegDef[SuperReg];
if (LastRef && LastRef != MI) {
if (hasRegisterUseBelow(SuperReg, MI, MI->getParent())) {
MI->addOperand(MachineOperand::CreateReg(SuperReg, false,
true,true));
MI->addOperand(MachineOperand::CreateReg(SuperReg, true,
true));
PhysRegDef[SuperReg] = MI;
PhysRegUse[SuperReg] = NULL;
Processed.insert(SuperReg);
for (const unsigned *SS = TRI->getSubRegisters(SuperReg); *SS; ++SS) {
PhysRegDef[*SS] = MI;
PhysRegUse[*SS] = NULL;
Processed.insert(*SS);
}
} else {
if (HandlePhysRegKill(SuperReg, MI)) {
PhysRegDef[SuperReg] = NULL;
PhysRegUse[SuperReg] = NULL;
for (const unsigned *SS = TRI->getSubRegisters(SuperReg); *SS; ++SS) {
PhysRegDef[*SS] = NULL;
PhysRegUse[*SS] = NULL;
Processed.insert(*SS);
}
}
}
}
}
PhysRegDef[Reg] = MI;
PhysRegUse[Reg] = NULL;
for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
PhysRegDef[SubReg] = MI;
PhysRegUse[SubReg] = NULL;
}
}
}
bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
MF = &mf;
MRI = &mf.getRegInfo();
TRI = MF->getTarget().getRegisterInfo();
ReservedRegisters = TRI->getReservedRegs(mf);
unsigned NumRegs = TRI->getNumRegs();
PhysRegDef = new MachineInstr*[NumRegs];
PhysRegUse = new MachineInstr*[NumRegs];
PHIVarInfo = new SmallVector<unsigned, 4>[MF->getNumBlockIDs()];
std::fill(PhysRegDef, PhysRegDef + NumRegs, (MachineInstr*)0);
std::fill(PhysRegUse, PhysRegUse + NumRegs, (MachineInstr*)0);
VirtRegInfo.resize(64);
analyzePHINodes(mf);
MachineBasicBlock *Entry = MF->begin();
SmallPtrSet<MachineBasicBlock*,16> Visited;
for (df_ext_iterator<MachineBasicBlock*, SmallPtrSet<MachineBasicBlock*,16> >
DFI = df_ext_begin(Entry, Visited), E = df_ext_end(Entry, Visited);
DFI != E; ++DFI) {
MachineBasicBlock *MBB = *DFI;
for (MachineBasicBlock::const_livein_iterator II = MBB->livein_begin(),
EE = MBB->livein_end(); II != EE; ++II) {
assert(TargetRegisterInfo::isPhysicalRegister(*II) &&
"Cannot have a live-in virtual register!");
HandlePhysRegDef(*II, 0);
}
DistanceMap.clear();
unsigned Dist = 0;
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
I != E; ++I) {
MachineInstr *MI = I;
DistanceMap.insert(std::make_pair(MI, Dist++));
unsigned NumOperandsToProcess = MI->getNumOperands();
if (MI->getOpcode() == TargetInstrInfo::PHI)
NumOperandsToProcess = 1;
SmallVector<unsigned, 4> UseRegs;
SmallVector<unsigned, 4> DefRegs;
for (unsigned i = 0; i != NumOperandsToProcess; ++i) {
const MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || MO.getReg() == 0)
continue;
unsigned MOReg = MO.getReg();
if (MO.isUse())
UseRegs.push_back(MOReg);
if (MO.isDef())
DefRegs.push_back(MOReg);
}
for (unsigned i = 0, e = UseRegs.size(); i != e; ++i) {
unsigned MOReg = UseRegs[i];
if (TargetRegisterInfo::isVirtualRegister(MOReg))
HandleVirtRegUse(MOReg, MBB, MI);
else if (!ReservedRegisters[MOReg])
HandlePhysRegUse(MOReg, MI);
}
for (unsigned i = 0, e = DefRegs.size(); i != e; ++i) {
unsigned MOReg = DefRegs[i];
if (TargetRegisterInfo::isVirtualRegister(MOReg))
HandleVirtRegDef(MOReg, MI);
else if (!ReservedRegisters[MOReg])
HandlePhysRegDef(MOReg, MI);
}
}
if (!PHIVarInfo[MBB->getNumber()].empty()) {
SmallVector<unsigned, 4>& VarInfoVec = PHIVarInfo[MBB->getNumber()];
for (SmallVector<unsigned, 4>::iterator I = VarInfoVec.begin(),
E = VarInfoVec.end(); I != E; ++I)
MarkVirtRegAliveInBlock(getVarInfo(*I),MRI->getVRegDef(*I)->getParent(),
MBB);
}
if (!MBB->empty() && MBB->back().getDesc().isReturn()) {
MachineInstr *Ret = &MBB->back();
for (MachineRegisterInfo::liveout_iterator
I = MF->getRegInfo().liveout_begin(),
E = MF->getRegInfo().liveout_end(); I != E; ++I) {
assert(TargetRegisterInfo::isPhysicalRegister(*I) &&
"Cannot have a live-out virtual register!");
HandlePhysRegUse(*I, Ret);
if (!Ret->readsRegister(*I))
Ret->addOperand(MachineOperand::CreateReg(*I, false, true));
}
}
for (unsigned i = 0; i != NumRegs; ++i)
if (PhysRegDef[i] || PhysRegUse[i])
HandlePhysRegDef(i, 0);
std::fill(PhysRegDef, PhysRegDef + NumRegs, (MachineInstr*)0);
std::fill(PhysRegUse, PhysRegUse + NumRegs, (MachineInstr*)0);
}
for (unsigned i = 0, e1 = VirtRegInfo.size(); i != e1; ++i)
for (unsigned j = 0, e2 = VirtRegInfo[i].Kills.size(); j != e2; ++j)
if (VirtRegInfo[i].Kills[j] ==
MRI->getVRegDef(i + TargetRegisterInfo::FirstVirtualRegister))
VirtRegInfo[i]
.Kills[j]->addRegisterDead(i +
TargetRegisterInfo::FirstVirtualRegister,
TRI);
else
VirtRegInfo[i]
.Kills[j]->addRegisterKilled(i +
TargetRegisterInfo::FirstVirtualRegister,
TRI);
#ifndef NDEBUG
for(MachineFunction::iterator i = MF->begin(), e = MF->end(); i != e; ++i)
assert(Visited.count(&*i) != 0 && "unreachable basic block found");
#endif
delete[] PhysRegDef;
delete[] PhysRegUse;
delete[] PHIVarInfo;
return false;
}
void LiveVariables::replaceKillInstruction(unsigned Reg, MachineInstr *OldMI,
MachineInstr *NewMI) {
VarInfo &VI = getVarInfo(Reg);
std::replace(VI.Kills.begin(), VI.Kills.end(), OldMI, NewMI);
}
void LiveVariables::removeVirtualRegistersKilled(MachineInstr *MI) {
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (MO.isReg() && MO.isKill()) {
MO.setIsKill(false);
unsigned Reg = MO.getReg();
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
bool removed = getVarInfo(Reg).removeKill(MI);
assert(removed && "kill not in register's VarInfo?");
removed = true;
}
}
}
}
void LiveVariables::analyzePHINodes(const MachineFunction& Fn) {
for (MachineFunction::const_iterator I = Fn.begin(), E = Fn.end();
I != E; ++I)
for (MachineBasicBlock::const_iterator BBI = I->begin(), BBE = I->end();
BBI != BBE && BBI->getOpcode() == TargetInstrInfo::PHI; ++BBI)
for (unsigned i = 1, e = BBI->getNumOperands(); i != e; i += 2)
PHIVarInfo[BBI->getOperand(i + 1).getMBB()->getNumber()]
.push_back(BBI->getOperand(i).getReg());
}