#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
+#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.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;
void LiveVariables::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredID(UnreachableMachineBlockElimID);
AU.setPreservesAll();
+ MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+MachineInstr *
+LiveVariables::VarInfo::findKill(const MachineBasicBlock *MBB) const {
+ for (unsigned i = 0, e = Kills.size(); i != e; ++i)
+ if (Kills[i]->getParent() == MBB)
+ return Kills[i];
+ return NULL;
}
void LiveVariables::VarInfo::dump() const {
- cerr << " Alive in blocks: ";
+ dbgs() << " Alive in blocks: ";
for (SparseBitVector<>::iterator I = AliveBlocks.begin(),
E = AliveBlocks.end(); I != E; ++I)
- cerr << *I << ", ";
- cerr << "\n Killed by:";
+ dbgs() << *I << ", ";
+ dbgs() << "\n Killed by:";
if (Kills.empty())
- cerr << " No instructions.\n";
+ dbgs() << " No instructions.\n";
else {
for (unsigned i = 0, e = Kills.size(); i != e; ++i)
- cerr << "\n #" << i << ": " << *Kills[i];
- cerr << "\n";
+ dbgs() << "\n #" << i << ": " << *Kills[i];
+ dbgs() << "\n";
}
}
}
/// FindLastPartialDef - Return the last partial def of the specified register.
-/// Also returns the sub-register that's defined.
+/// Also returns the sub-registers that're defined by the instruction.
MachineInstr *LiveVariables::FindLastPartialDef(unsigned Reg,
- unsigned &PartDefReg) {
+ SmallSet<unsigned,4> &PartDefRegs) {
unsigned LastDefReg = 0;
unsigned LastDefDist = 0;
MachineInstr *LastDef = NULL;
LastDefDist = Dist;
}
}
- PartDefReg = LastDefReg;
+
+ if (!LastDef)
+ return 0;
+
+ PartDefRegs.insert(LastDefReg);
+ for (unsigned i = 0, e = LastDef->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = LastDef->getOperand(i);
+ if (!MO.isReg() || !MO.isDef() || MO.getReg() == 0)
+ continue;
+ unsigned DefReg = MO.getReg();
+ if (TRI->isSubRegister(Reg, DefReg)) {
+ PartDefRegs.insert(DefReg);
+ for (const unsigned *SubRegs = TRI->getSubRegisters(DefReg);
+ unsigned SubReg = *SubRegs; ++SubRegs)
+ PartDefRegs.insert(SubReg);
+ }
+ }
return LastDef;
}
/// implicit defs to a machine instruction if there was an earlier def of its
/// super-register.
void LiveVariables::HandlePhysRegUse(unsigned Reg, MachineInstr *MI) {
+ MachineInstr *LastDef = PhysRegDef[Reg];
// If there was a previous use or a "full" def all is well.
- if (!PhysRegDef[Reg] && !PhysRegUse[Reg]) {
+ if (!LastDef && !PhysRegUse[Reg]) {
// Otherwise, the last sub-register def implicitly defines this register.
// e.g.
// AH =
// ...
// = EAX
// All of the sub-registers must have been defined before the use of Reg!
- unsigned PartDefReg = 0;
- MachineInstr *LastPartialDef = FindLastPartialDef(Reg, PartDefReg);
+ SmallSet<unsigned, 4> PartDefRegs;
+ MachineInstr *LastPartialDef = FindLastPartialDef(Reg, PartDefRegs);
// If LastPartialDef is NULL, it must be using a livein register.
if (LastPartialDef) {
LastPartialDef->addOperand(MachineOperand::CreateReg(Reg, true/*IsDef*/,
unsigned SubReg = *SubRegs; ++SubRegs) {
if (Processed.count(SubReg))
continue;
- if (SubReg == PartDefReg || TRI->isSubRegister(PartDefReg, SubReg))
+ if (PartDefRegs.count(SubReg))
continue;
// This part of Reg was defined before the last partial def. It's killed
// here.
}
}
}
+ else if (LastDef && !PhysRegUse[Reg] &&
+ !LastDef->findRegisterDefOperand(Reg))
+ // Last def defines the super register, add an implicit def of reg.
+ LastDef->addOperand(MachineOperand::CreateReg(Reg,
+ true/*IsDef*/, true/*IsImp*/));
// Remember this use.
PhysRegUse[Reg] = MI;
PhysRegUse[SubReg] = MI;
}
-/// hasRegisterUseBelow - Return true if the specified register is used after
-/// the current instruction and before it's next definition.
-bool LiveVariables::hasRegisterUseBelow(unsigned Reg,
- MachineBasicBlock::iterator I,
- MachineBasicBlock *MBB) {
- if (I == MBB->end())
+/// FindLastRefOrPartRef - Return the last reference or partial reference of
+/// the specified register.
+MachineInstr *LiveVariables::FindLastRefOrPartRef(unsigned Reg) {
+ MachineInstr *LastDef = PhysRegDef[Reg];
+ MachineInstr *LastUse = PhysRegUse[Reg];
+ if (!LastDef && !LastUse)
return false;
- // First find out if there are any uses / defs below.
- 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()) {
- // Must be below if it hasn't been assigned a distance yet.
- 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);
+ MachineInstr *LastRefOrPartRef = LastUse ? LastUse : LastDef;
+ unsigned LastRefOrPartRefDist = DistanceMap[LastRefOrPartRef];
+ unsigned LastPartDefDist = 0;
+ for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
+ unsigned SubReg = *SubRegs; ++SubRegs) {
+ MachineInstr *Def = PhysRegDef[SubReg];
+ if (Def && Def != LastDef) {
+ // There was a def of this sub-register in between. This is a partial
+ // def, keep track of the last one.
+ unsigned Dist = DistanceMap[Def];
+ if (Dist > LastPartDefDist)
+ LastPartDefDist = Dist;
+ } else if (MachineInstr *Use = PhysRegUse[SubReg]) {
+ unsigned Dist = DistanceMap[Use];
+ if (Dist > LastRefOrPartRefDist) {
+ LastRefOrPartRefDist = Dist;
+ LastRefOrPartRef = Use;
+ }
}
}
- if (Uses.empty())
- // No uses below.
- return false;
- else if (!Uses.empty() && Defs.empty())
- // There are uses below but no defs below.
- return true;
- // There are both uses and defs below. We need to know which comes first.
- if (!hasDistInfo) {
- // Complete DistanceMap for this MBB. This information is computed only
- // once per MBB.
- ++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)
- // The register is defined before its first use below.
- return false;
- }
- return true;
+ return LastRefOrPartRef;
}
bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) {
- if (!PhysRegUse[Reg] && !PhysRegDef[Reg])
+ MachineInstr *LastDef = PhysRegDef[Reg];
+ MachineInstr *LastUse = PhysRegUse[Reg];
+ if (!LastDef && !LastUse)
return false;
- MachineInstr *LastRefOrPartRef = PhysRegUse[Reg]
- ? PhysRegUse[Reg] : PhysRegDef[Reg];
+ MachineInstr *LastRefOrPartRef = LastUse ? LastUse : LastDef;
unsigned LastRefOrPartRefDist = DistanceMap[LastRefOrPartRef];
// The whole register is used.
// AL =
// AX<dead> = AL<imp-def>
// = AL<kill>
// AX =
+ MachineInstr *LastPartDef = 0;
+ unsigned LastPartDefDist = 0;
SmallSet<unsigned, 8> PartUses;
for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
+ MachineInstr *Def = PhysRegDef[SubReg];
+ if (Def && Def != LastDef) {
+ // There was a def of this sub-register in between. This is a partial
+ // def, keep track of the last one.
+ unsigned Dist = DistanceMap[Def];
+ if (Dist > LastPartDefDist) {
+ LastPartDefDist = Dist;
+ LastPartDef = Def;
+ }
+ continue;
+ }
if (MachineInstr *Use = PhysRegUse[SubReg]) {
PartUses.insert(SubReg);
for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
}
}
- if (LastRefOrPartRef == PhysRegDef[Reg] && LastRefOrPartRef != MI)
- // If the last reference is the last def, then it's not used at all.
- // That is, unless we are currently processing the last reference itself.
- LastRefOrPartRef->addRegisterDead(Reg, TRI, true);
-
- // Partial uses. Mark register def dead and add implicit def of
- // sub-registers which are used.
- // EAX<dead> = op AL<imp-def>
- // That is, EAX def is dead but AL def extends pass it.
- // Enable this after live interval analysis is fixed to improve codegen!
- else if (!PhysRegUse[Reg]) {
+ if (LastRefOrPartRef == PhysRegDef[Reg] && LastRefOrPartRef != MI) {
+ if (LastPartDef)
+ // The last partial def kills the register.
+ LastPartDef->addOperand(MachineOperand::CreateReg(Reg, false/*IsDef*/,
+ true/*IsImp*/, true/*IsKill*/));
+ else {
+ MachineOperand *MO =
+ LastRefOrPartRef->findRegisterDefOperand(Reg, false, TRI);
+ bool NeedEC = MO->isEarlyClobber() && MO->getReg() != Reg;
+ // If the last reference is the last def, then it's not used at all.
+ // That is, unless we are currently processing the last reference itself.
+ LastRefOrPartRef->addRegisterDead(Reg, TRI, true);
+ if (NeedEC) {
+ // If we are adding a subreg def and the superreg def is marked early
+ // clobber, add an early clobber marker to the subreg def.
+ MO = LastRefOrPartRef->findRegisterDefOperand(Reg);
+ if (MO)
+ MO->setIsEarlyClobber();
+ }
+ }
+ } else if (!PhysRegUse[Reg]) {
+ // Partial uses. Mark register def dead and add implicit def of
+ // sub-registers which are used.
+ // EAX<dead> = op AL<imp-def>
+ // That is, EAX def is dead but AL def extends pass it.
PhysRegDef[Reg]->addRegisterDead(Reg, TRI, true);
for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
unsigned SubReg = *SubRegs; ++SubRegs) {
- if (PartUses.count(SubReg)) {
+ if (!PartUses.count(SubReg))
+ continue;
+ bool NeedDef = true;
+ if (PhysRegDef[Reg] == PhysRegDef[SubReg]) {
+ MachineOperand *MO = PhysRegDef[Reg]->findRegisterDefOperand(SubReg);
+ if (MO) {
+ NeedDef = false;
+ assert(!MO->isDead());
+ }
+ }
+ if (NeedDef)
PhysRegDef[Reg]->addOperand(MachineOperand::CreateReg(SubReg,
- true, true));
+ true/*IsDef*/, true/*IsImp*/));
+ MachineInstr *LastSubRef = FindLastRefOrPartRef(SubReg);
+ if (LastSubRef)
+ LastSubRef->addRegisterKilled(SubReg, TRI, true);
+ else {
LastRefOrPartRef->addRegisterKilled(SubReg, TRI, true);
- for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
- PartUses.erase(*SS);
+ PhysRegUse[SubReg] = LastRefOrPartRef;
+ for (const unsigned *SSRegs = TRI->getSubRegisters(SubReg);
+ unsigned SSReg = *SSRegs; ++SSRegs)
+ PhysRegUse[SSReg] = LastRefOrPartRef;
}
+ for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
+ PartUses.erase(*SS);
}
- }
- else
+ } else
LastRefOrPartRef->addRegisterKilled(Reg, TRI, true);
return true;
}
-void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI) {
+void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI,
+ SmallVector<unsigned, 4> &Defs) {
// What parts of the register are previously defined?
SmallSet<unsigned, 32> Live;
if (PhysRegDef[Reg] || PhysRegUse[Reg]) {
// AL =
// AH =
// = AX
+ if (Live.count(SubReg))
+ continue;
if (PhysRegDef[SubReg] || PhysRegUse[SubReg]) {
Live.insert(SubReg);
for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
// Start from the largest piece, find the last time any part of the register
// is referenced.
- if (!HandlePhysRegKill(Reg, MI)) {
- // Only some of the sub-registers are used.
- for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
- unsigned SubReg = *SubRegs; ++SubRegs) {
- if (!Live.count(SubReg))
- // Skip if this sub-register isn't defined.
- 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?");
+ HandlePhysRegKill(Reg, MI);
+ // Only some of the sub-registers are used.
+ for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
+ unsigned SubReg = *SubRegs; ++SubRegs) {
+ if (!Live.count(SubReg))
+ // Skip if this sub-register isn't defined.
+ continue;
+ HandlePhysRegKill(SubReg, MI);
}
- if (MI) {
- // Does this extend the live range of a super-register?
- 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) {
- // The larger register is previously defined. Now a smaller part is
- // being re-defined. Treat it as read/mod/write if there are uses
- // below.
- // EAX =
- // AX = EAX<imp-use,kill>, EAX<imp-def>
- // ...
- /// = EAX
- if (hasRegisterUseBelow(SuperReg, MI, MI->getParent())) {
- MI->addOperand(MachineOperand::CreateReg(SuperReg, false/*IsDef*/,
- true/*IsImp*/,true/*IsKill*/));
- MI->addOperand(MachineOperand::CreateReg(SuperReg, true/*IsDef*/,
- true/*IsImp*/));
- 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 {
- // Otherwise, the super register is killed.
- 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);
- }
- }
- }
- }
- }
+ if (MI)
+ Defs.push_back(Reg); // Remember this def.
+}
- // Remember this def.
+void LiveVariables::UpdatePhysRegDefs(MachineInstr *MI,
+ SmallVector<unsigned, 4> &Defs) {
+ while (!Defs.empty()) {
+ unsigned Reg = Defs.back();
+ Defs.pop_back();
PhysRegDef[Reg] = MI;
PhysRegUse[Reg] = NULL;
for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
}
}
+namespace {
+ struct RegSorter {
+ const TargetRegisterInfo *TRI;
+
+ RegSorter(const TargetRegisterInfo *tri) : TRI(tri) { }
+ bool operator()(unsigned A, unsigned B) {
+ if (TRI->isSubRegister(A, B))
+ return true;
+ else if (TRI->isSubRegister(B, A))
+ return false;
+ return A < B;
+ }
+ };
+}
+
bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
MF = &mf;
MRI = &mf.getRegInfo();
MachineBasicBlock *MBB = *DFI;
// Mark live-in registers as live-in.
+ SmallVector<unsigned, 4> Defs;
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);
+ HandlePhysRegDef(*II, 0, Defs);
}
// Loop over all of the instructions, processing them.
if (TargetRegisterInfo::isVirtualRegister(MOReg))
HandleVirtRegDef(MOReg, MI);
else if (!ReservedRegisters[MOReg])
- HandlePhysRegDef(MOReg, MI);
+ HandlePhysRegDef(MOReg, MI, Defs);
}
+ UpdatePhysRegDefs(MI, Defs);
}
// Handle any virtual assignments from PHI nodes which might be at the
// available at the end of the basic block.
for (unsigned i = 0; i != NumRegs; ++i)
if (PhysRegDef[i] || PhysRegUse[i])
- HandlePhysRegDef(i, 0);
+ HandlePhysRegDef(i, 0, Defs);
std::fill(PhysRegDef, PhysRegDef + NumRegs, (MachineInstr*)0);
std::fill(PhysRegUse, PhysRegUse + NumRegs, (MachineInstr*)0);
PHIVarInfo[BBI->getOperand(i + 1).getMBB()->getNumber()]
.push_back(BBI->getOperand(i).getReg());
}
+
+bool LiveVariables::VarInfo::isLiveIn(const MachineBasicBlock &MBB,
+ unsigned Reg,
+ MachineRegisterInfo &MRI) {
+ unsigned Num = MBB.getNumber();
+
+ // Reg is live-through.
+ if (AliveBlocks.test(Num))
+ return true;
+
+ // Registers defined in MBB cannot be live in.
+ const MachineInstr *Def = MRI.getVRegDef(Reg);
+ if (Def && Def->getParent() == &MBB)
+ return false;
+
+ // Reg was not defined in MBB, was it killed here?
+ return findKill(&MBB);
+}
+
+bool LiveVariables::isLiveOut(unsigned Reg, const MachineBasicBlock &MBB) {
+ LiveVariables::VarInfo &VI = getVarInfo(Reg);
+
+ // Loop over all of the successors of the basic block, checking to see if
+ // the value is either live in the block, or if it is killed in the block.
+ std::vector<MachineBasicBlock*> OpSuccBlocks;
+ for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
+ E = MBB.succ_end(); SI != E; ++SI) {
+ MachineBasicBlock *SuccMBB = *SI;
+
+ // Is it alive in this successor?
+ unsigned SuccIdx = SuccMBB->getNumber();
+ if (VI.AliveBlocks.test(SuccIdx))
+ return true;
+ OpSuccBlocks.push_back(SuccMBB);
+ }
+
+ // Check to see if this value is live because there is a use in a successor
+ // that kills it.
+ switch (OpSuccBlocks.size()) {
+ case 1: {
+ MachineBasicBlock *SuccMBB = OpSuccBlocks[0];
+ for (unsigned i = 0, e = VI.Kills.size(); i != e; ++i)
+ if (VI.Kills[i]->getParent() == SuccMBB)
+ return true;
+ break;
+ }
+ case 2: {
+ MachineBasicBlock *SuccMBB1 = OpSuccBlocks[0], *SuccMBB2 = OpSuccBlocks[1];
+ for (unsigned i = 0, e = VI.Kills.size(); i != e; ++i)
+ if (VI.Kills[i]->getParent() == SuccMBB1 ||
+ VI.Kills[i]->getParent() == SuccMBB2)
+ return true;
+ break;
+ }
+ default:
+ std::sort(OpSuccBlocks.begin(), OpSuccBlocks.end());
+ for (unsigned i = 0, e = VI.Kills.size(); i != e; ++i)
+ if (std::binary_search(OpSuccBlocks.begin(), OpSuccBlocks.end(),
+ VI.Kills[i]->getParent()))
+ return true;
+ }
+ return false;
+}
+
+/// addNewBlock - Add a new basic block BB as an empty succcessor to DomBB. All
+/// variables that are live out of DomBB will be marked as passing live through
+/// BB.
+void LiveVariables::addNewBlock(MachineBasicBlock *BB,
+ MachineBasicBlock *DomBB,
+ MachineBasicBlock *SuccBB) {
+ const unsigned NumNew = BB->getNumber();
+
+ // All registers used by PHI nodes in SuccBB must be live through BB.
+ for (MachineBasicBlock::const_iterator BBI = SuccBB->begin(),
+ BBE = SuccBB->end();
+ BBI != BBE && BBI->getOpcode() == TargetInstrInfo::PHI; ++BBI)
+ for (unsigned i = 1, e = BBI->getNumOperands(); i != e; i += 2)
+ if (BBI->getOperand(i+1).getMBB() == BB)
+ getVarInfo(BBI->getOperand(i).getReg()).AliveBlocks.set(NumNew);
+
+ // Update info for all live variables
+ for (unsigned Reg = TargetRegisterInfo::FirstVirtualRegister,
+ E = MRI->getLastVirtReg()+1; Reg != E; ++Reg) {
+ VarInfo &VI = getVarInfo(Reg);
+ if (!VI.AliveBlocks.test(NumNew) && VI.isLiveIn(*SuccBB, Reg, *MRI))
+ VI.AliveBlocks.set(NumNew);
+ }
+}