X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FLiveVariables.cpp;h=ed3138453498b310e21b4c013d83f09df2886a04;hb=ab6ab3c33363452bc53c119dc36ad650f6c267d7;hp=03f8221e1f6e385482af1a1f576ae471e1a2f194;hpb=7c2a4a30e0e16762c75adacebd05ec9fcbccf16b;p=oota-llvm.git diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp index 03f8221e1f6..ed313845349 100644 --- a/lib/CodeGen/LiveVariables.cpp +++ b/lib/CodeGen/LiveVariables.cpp @@ -14,7 +14,7 @@ // the instruction, but are never used after the instruction (i.e., they are // killed). // -// This class computes live variables using are sparse implementation based on +// This class computes live variables using a sparse implementation based on // the machine code SSA form. This class computes live variable information for // each virtual and _register allocatable_ physical register in a function. It // uses the dominance properties of SSA form to efficiently compute live @@ -27,20 +27,22 @@ //===----------------------------------------------------------------------===// #include "llvm/CodeGen/LiveVariables.h" +#include "llvm/ADT/DepthFirstIterator.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/SmallSet.h" #include "llvm/CodeGen/MachineInstr.h" #include "llvm/CodeGen/MachineRegisterInfo.h" #include "llvm/CodeGen/Passes.h" #include "llvm/Support/Debug.h" +#include "llvm/Support/ErrorHandling.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 using namespace llvm; char LiveVariables::ID = 0; +char &llvm::LiveVariablesID = LiveVariables::ID; INITIALIZE_PASS_BEGIN(LiveVariables, "livevars", "Live Variable Analysis", false, false) INITIALIZE_PASS_DEPENDENCY(UnreachableMachineBlockElim) @@ -59,10 +61,11 @@ 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; + return nullptr; } void LiveVariables::VarInfo::dump() const { +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) dbgs() << " Alive in blocks: "; for (SparseBitVector<>::iterator I = AliveBlocks.begin(), E = AliveBlocks.end(); I != E; ++I) @@ -75,6 +78,7 @@ void LiveVariables::VarInfo::dump() const { dbgs() << "\n #" << i << ": " << *Kills[i]; dbgs() << "\n"; } +#endif } /// getVarInfo - Get (possibly creating) a VarInfo object for the given vreg. @@ -90,7 +94,7 @@ void LiveVariables::MarkVirtRegAliveInBlock(VarInfo& VRInfo, MachineBasicBlock *MBB, std::vector &WorkList) { unsigned BBNum = MBB->getNumber(); - + // Check to see if this basic block is one of the killing blocks. If so, // remove it. for (unsigned i = 0, e = VRInfo.Kills.size(); i != e; ++i) @@ -98,7 +102,7 @@ void LiveVariables::MarkVirtRegAliveInBlock(VarInfo& VRInfo, VRInfo.Kills.erase(VRInfo.Kills.begin()+i); // Erase entry break; } - + if (MBB == DefBlock) return; // Terminate recursion if (VRInfo.AliveBlocks.test(BBNum)) @@ -107,6 +111,7 @@ void LiveVariables::MarkVirtRegAliveInBlock(VarInfo& VRInfo, // Mark the variable known alive in this bb VRInfo.AliveBlocks.set(BBNum); + assert(MBB != &MF->front() && "Can't find reaching def for virtreg"); WorkList.insert(WorkList.end(), MBB->pred_rbegin(), MBB->pred_rend()); } @@ -130,7 +135,6 @@ void LiveVariables::HandleVirtRegUse(unsigned reg, MachineBasicBlock *MBB, unsigned BBNum = MBB->getNumber(); VarInfo& VRInfo = getVarInfo(reg); - VRInfo.NumUses++; // Check to see if this basic block is already a kill block. if (!VRInfo.Kills.empty() && VRInfo.Kills.back()->getParent() == MBB) { @@ -189,9 +193,9 @@ MachineInstr *LiveVariables::FindLastPartialDef(unsigned Reg, SmallSet &PartDefRegs) { unsigned LastDefReg = 0; unsigned LastDefDist = 0; - MachineInstr *LastDef = NULL; - for (const unsigned *SubRegs = TRI->getSubRegisters(Reg); - unsigned SubReg = *SubRegs; ++SubRegs) { + MachineInstr *LastDef = nullptr; + for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) { + unsigned SubReg = *SubRegs; MachineInstr *Def = PhysRegDef[SubReg]; if (!Def) continue; @@ -204,7 +208,7 @@ MachineInstr *LiveVariables::FindLastPartialDef(unsigned Reg, } if (!LastDef) - return 0; + return nullptr; PartDefRegs.insert(LastDefReg); for (unsigned i = 0, e = LastDef->getNumOperands(); i != e; ++i) { @@ -213,10 +217,9 @@ MachineInstr *LiveVariables::FindLastPartialDef(unsigned Reg, 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); + for (MCSubRegIterator SubRegs(DefReg, TRI, /*IncludeSelf=*/true); + SubRegs.isValid(); ++SubRegs) + PartDefRegs.insert(*SubRegs); } } return LastDef; @@ -245,8 +248,8 @@ void LiveVariables::HandlePhysRegUse(unsigned Reg, MachineInstr *MI) { true/*IsImp*/)); PhysRegDef[Reg] = LastPartialDef; SmallSet Processed; - for (const unsigned *SubRegs = TRI->getSubRegisters(Reg); - unsigned SubReg = *SubRegs; ++SubRegs) { + for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) { + unsigned SubReg = *SubRegs; if (Processed.count(SubReg)) continue; if (PartDefRegs.count(SubReg)) @@ -257,22 +260,20 @@ void LiveVariables::HandlePhysRegUse(unsigned Reg, MachineInstr *MI) { false/*IsDef*/, true/*IsImp*/)); PhysRegDef[SubReg] = LastPartialDef; - for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS) + for (MCSubRegIterator SS(SubReg, TRI); SS.isValid(); ++SS) Processed.insert(*SS); } } - } - else if (LastDef && !PhysRegUse[Reg] && - !LastDef->findRegisterDefOperand(Reg)) + } 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*/)); + LastDef->addOperand(MachineOperand::CreateReg(Reg, true/*IsDef*/, + true/*IsImp*/)); // Remember this use. - PhysRegUse[Reg] = MI; - for (const unsigned *SubRegs = TRI->getSubRegisters(Reg); - unsigned SubReg = *SubRegs; ++SubRegs) - PhysRegUse[SubReg] = MI; + for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true); + SubRegs.isValid(); ++SubRegs) + PhysRegUse[*SubRegs] = MI; } /// FindLastRefOrPartRef - Return the last reference or partial reference of @@ -281,13 +282,13 @@ MachineInstr *LiveVariables::FindLastRefOrPartRef(unsigned Reg) { MachineInstr *LastDef = PhysRegDef[Reg]; MachineInstr *LastUse = PhysRegUse[Reg]; if (!LastDef && !LastUse) - return 0; + return nullptr; MachineInstr *LastRefOrPartRef = LastUse ? LastUse : LastDef; unsigned LastRefOrPartRefDist = DistanceMap[LastRefOrPartRef]; unsigned LastPartDefDist = 0; - for (const unsigned *SubRegs = TRI->getSubRegisters(Reg); - unsigned SubReg = *SubRegs; ++SubRegs) { + for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) { + unsigned SubReg = *SubRegs; MachineInstr *Def = PhysRegDef[SubReg]; if (Def && Def != LastDef) { // There was a def of this sub-register in between. This is a partial @@ -331,12 +332,12 @@ bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) { // Or whole register is defined, but only partly used. // AX = AL // = AL - // AX = - MachineInstr *LastPartDef = 0; + // AX = + MachineInstr *LastPartDef = nullptr; unsigned LastPartDefDist = 0; SmallSet PartUses; - for (const unsigned *SubRegs = TRI->getSubRegisters(Reg); - unsigned SubReg = *SubRegs; ++SubRegs) { + for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) { + unsigned SubReg = *SubRegs; MachineInstr *Def = PhysRegDef[SubReg]; if (Def && Def != LastDef) { // There was a def of this sub-register in between. This is a partial @@ -349,8 +350,8 @@ bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) { continue; } if (MachineInstr *Use = PhysRegUse[SubReg]) { - PartUses.insert(SubReg); - for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS) + for (MCSubRegIterator SS(SubReg, TRI, /*IncludeSelf=*/true); SS.isValid(); + ++SS) PartUses.insert(*SS); unsigned Dist = DistanceMap[Use]; if (Dist > LastRefOrPartRefDist) { @@ -366,8 +367,8 @@ bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) { // EAX = op AL // 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) { + for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) { + unsigned SubReg = *SubRegs; if (!PartUses.count(SubReg)) continue; bool NeedDef = true; @@ -386,12 +387,11 @@ bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) { LastSubRef->addRegisterKilled(SubReg, TRI, true); else { LastRefOrPartRef->addRegisterKilled(SubReg, TRI, true); - PhysRegUse[SubReg] = LastRefOrPartRef; - for (const unsigned *SSRegs = TRI->getSubRegisters(SubReg); - unsigned SSReg = *SSRegs; ++SSRegs) - PhysRegUse[SSReg] = LastRefOrPartRef; + for (MCSubRegIterator SS(SubReg, TRI, /*IncludeSelf=*/true); + SS.isValid(); ++SS) + PhysRegUse[*SS] = LastRefOrPartRef; } - for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS) + for (MCSubRegIterator SS(SubReg, TRI); SS.isValid(); ++SS) PartUses.erase(*SS); } } else if (LastRefOrPartRef == PhysRegDef[Reg] && LastRefOrPartRef != MI) { @@ -419,17 +419,38 @@ bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) { return true; } +void LiveVariables::HandleRegMask(const MachineOperand &MO) { + // Call HandlePhysRegKill() for all live registers clobbered by Mask. + // Clobbered registers are always dead, sp there is no need to use + // HandlePhysRegDef(). + for (unsigned Reg = 1, NumRegs = TRI->getNumRegs(); Reg != NumRegs; ++Reg) { + // Skip dead regs. + if (!PhysRegDef[Reg] && !PhysRegUse[Reg]) + continue; + // Skip mask-preserved regs. + if (!MO.clobbersPhysReg(Reg)) + continue; + // Kill the largest clobbered super-register. + // This avoids needless implicit operands. + unsigned Super = Reg; + for (MCSuperRegIterator SR(Reg, TRI); SR.isValid(); ++SR) + if ((PhysRegDef[*SR] || PhysRegUse[*SR]) && MO.clobbersPhysReg(*SR)) + Super = *SR; + HandlePhysRegKill(Super, nullptr); + } +} + void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI, - SmallVector &Defs) { + SmallVectorImpl &Defs) { // What parts of the register are previously defined? SmallSet Live; if (PhysRegDef[Reg] || PhysRegUse[Reg]) { - Live.insert(Reg); - for (const unsigned *SS = TRI->getSubRegisters(Reg); *SS; ++SS) - Live.insert(*SS); + for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true); + SubRegs.isValid(); ++SubRegs) + Live.insert(*SubRegs); } else { - for (const unsigned *SubRegs = TRI->getSubRegisters(Reg); - unsigned SubReg = *SubRegs; ++SubRegs) { + for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) { + unsigned SubReg = *SubRegs; // If a register isn't itself defined, but all parts that make up of it // are defined, then consider it also defined. // e.g. @@ -439,8 +460,8 @@ void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI, if (Live.count(SubReg)) continue; if (PhysRegDef[SubReg] || PhysRegUse[SubReg]) { - Live.insert(SubReg); - for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS) + for (MCSubRegIterator SS(SubReg, TRI, /*IncludeSelf=*/true); + SS.isValid(); ++SS) Live.insert(*SS); } } @@ -450,8 +471,8 @@ void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI, // is referenced. HandlePhysRegKill(Reg, MI); // Only some of the sub-registers are used. - for (const unsigned *SubRegs = TRI->getSubRegisters(Reg); - unsigned SubReg = *SubRegs; ++SubRegs) { + for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) { + unsigned SubReg = *SubRegs; if (!Live.count(SubReg)) // Skip if this sub-register isn't defined. continue; @@ -463,16 +484,15 @@ void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI, } void LiveVariables::UpdatePhysRegDefs(MachineInstr *MI, - SmallVector &Defs) { + SmallVectorImpl &Defs) { while (!Defs.empty()) { unsigned Reg = Defs.back(); Defs.pop_back(); - PhysRegDef[Reg] = MI; - PhysRegUse[Reg] = NULL; - for (const unsigned *SubRegs = TRI->getSubRegisters(Reg); - unsigned SubReg = *SubRegs; ++SubRegs) { + for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true); + SubRegs.isValid(); ++SubRegs) { + unsigned SubReg = *SubRegs; PhysRegDef[SubReg] = MI; - PhysRegUse[SubReg] = NULL; + PhysRegUse[SubReg] = nullptr; } } } @@ -482,16 +502,20 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &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[MF->getNumBlockIDs()]; - std::fill(PhysRegDef, PhysRegDef + NumRegs, (MachineInstr*)0); - std::fill(PhysRegUse, PhysRegUse + NumRegs, (MachineInstr*)0); + std::fill(PhysRegDef, PhysRegDef + NumRegs, nullptr); + std::fill(PhysRegUse, PhysRegUse + NumRegs, nullptr); PHIJoins.clear(); + // FIXME: LiveIntervals will be updated to remove its dependence on + // LiveVariables to improve compilation time and eliminate bizarre pass + // dependencies. Until then, we can't change much in -O0. + if (!MRI->isSSA()) + report_fatal_error("regalloc=... not currently supported with -O0"); + analyzePHINodes(mf); // Calculate live variable information in depth first order on the CFG of the @@ -512,7 +536,7 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) { EE = MBB->livein_end(); II != EE; ++II) { assert(TargetRegisterInfo::isPhysicalRegister(*II) && "Cannot have a live-in virtual register!"); - HandlePhysRegDef(*II, 0, Defs); + HandlePhysRegDef(*II, nullptr, Defs); } // Loop over all of the instructions, processing them. @@ -536,14 +560,20 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) { // Clear kill and dead markers. LV will recompute them. SmallVector UseRegs; SmallVector DefRegs; + SmallVector RegMasks; for (unsigned i = 0; i != NumOperandsToProcess; ++i) { MachineOperand &MO = MI->getOperand(i); + if (MO.isRegMask()) { + RegMasks.push_back(i); + continue; + } if (!MO.isReg() || MO.getReg() == 0) continue; unsigned MOReg = MO.getReg(); if (MO.isUse()) { MO.setIsKill(false); - UseRegs.push_back(MOReg); + if (MO.readsReg()) + UseRegs.push_back(MOReg); } else /*MO.isDef()*/ { MO.setIsDead(false); DefRegs.push_back(MOReg); @@ -555,16 +585,20 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) { unsigned MOReg = UseRegs[i]; if (TargetRegisterInfo::isVirtualRegister(MOReg)) HandleVirtRegUse(MOReg, MBB, MI); - else if (!ReservedRegisters[MOReg]) + else if (!MRI->isReserved(MOReg)) HandlePhysRegUse(MOReg, MI); } + // Process all masked registers. (Call clobbers). + for (unsigned i = 0, e = RegMasks.size(); i != e; ++i) + HandleRegMask(MI->getOperand(RegMasks[i])); + // Process all defs. 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]) + else if (!MRI->isReserved(MOReg)) HandlePhysRegDef(MOReg, MI, Defs); } UpdatePhysRegDefs(MI, Defs); @@ -575,46 +609,40 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) { // if they have PHI nodes, and if so, we simulate an assignment at the end // of the current block. if (!PHIVarInfo[MBB->getNumber()].empty()) { - SmallVector& VarInfoVec = PHIVarInfo[MBB->getNumber()]; + SmallVectorImpl &VarInfoVec = PHIVarInfo[MBB->getNumber()]; - for (SmallVector::iterator I = VarInfoVec.begin(), + for (SmallVectorImpl::iterator I = VarInfoVec.begin(), E = VarInfoVec.end(); I != E; ++I) // Mark it alive only in the block we are representing. MarkVirtRegAliveInBlock(getVarInfo(*I),MRI->getVRegDef(*I)->getParent(), MBB); } - // Finally, if the last instruction in the block is a return, make sure to - // mark it as using all of the live-out values in the function. - // Things marked both call and return are tail calls; do not do this for - // them. The tail callee need not take the same registers as input - // that it produces as output, and there are dependencies for its input - // registers elsewhere. - if (!MBB->empty() && MBB->back().getDesc().isReturn() - && !MBB->back().getDesc().isCall()) { - 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); - - // Add live-out registers as implicit uses. - if (!Ret->readsRegister(*I)) - Ret->addOperand(MachineOperand::CreateReg(*I, false, true)); + // MachineCSE may CSE instructions which write to non-allocatable physical + // registers across MBBs. Remember if any reserved register is liveout. + SmallSet LiveOuts; + for (MachineBasicBlock::const_succ_iterator SI = MBB->succ_begin(), + SE = MBB->succ_end(); SI != SE; ++SI) { + MachineBasicBlock *SuccMBB = *SI; + if (SuccMBB->isLandingPad()) + continue; + for (MachineBasicBlock::livein_iterator LI = SuccMBB->livein_begin(), + LE = SuccMBB->livein_end(); LI != LE; ++LI) { + unsigned LReg = *LI; + if (!TRI->isInAllocatableClass(LReg)) + // Ignore other live-ins, e.g. those that are live into landing pads. + LiveOuts.insert(LReg); } } // Loop over PhysRegDef / PhysRegUse, killing any registers that are // available at the end of the basic block. for (unsigned i = 0; i != NumRegs; ++i) - if (PhysRegDef[i] || PhysRegUse[i]) - HandlePhysRegDef(i, 0, Defs); + if ((PhysRegDef[i] || PhysRegUse[i]) && !LiveOuts.count(i)) + HandlePhysRegDef(i, nullptr, Defs); - std::fill(PhysRegDef, PhysRegDef + NumRegs, (MachineInstr*)0); - std::fill(PhysRegUse, PhysRegUse + NumRegs, (MachineInstr*)0); + std::fill(PhysRegDef, PhysRegDef + NumRegs, nullptr); + std::fill(PhysRegUse, PhysRegUse + NumRegs, nullptr); } // Convert and transfer the dead / killed information we have gathered into @@ -678,8 +706,9 @@ void LiveVariables::analyzePHINodes(const MachineFunction& Fn) { for (MachineBasicBlock::const_iterator BBI = I->begin(), BBE = I->end(); BBI != BBE && BBI->isPHI(); ++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()); + if (BBI->getOperand(i).readsReg()) + PHIVarInfo[BBI->getOperand(i + 1).getMBB()->getNumber()] + .push_back(BBI->getOperand(i).getReg()); } bool LiveVariables::VarInfo::isLiveIn(const MachineBasicBlock &MBB, @@ -753,18 +782,44 @@ void LiveVariables::addNewBlock(MachineBasicBlock *BB, MachineBasicBlock *SuccBB) { const unsigned NumNew = BB->getNumber(); - // All registers used by PHI nodes in SuccBB must be live through BB. - for (MachineBasicBlock::iterator BBI = SuccBB->begin(), - BBE = SuccBB->end(); BBI != BBE && BBI->isPHI(); ++BBI) + SmallSet Defs, Kills; + + MachineBasicBlock::iterator BBI = SuccBB->begin(), BBE = SuccBB->end(); + for (; BBI != BBE && BBI->isPHI(); ++BBI) { + // Record the def of the PHI node. + Defs.insert(BBI->getOperand(0).getReg()); + + // All registers used by PHI nodes in SuccBB must be live through BB. 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); + } + + // Record all vreg defs and kills of all instructions in SuccBB. + for (; BBI != BBE; ++BBI) { + for (MachineInstr::mop_iterator I = BBI->operands_begin(), + E = BBI->operands_end(); I != E; ++I) { + if (I->isReg() && TargetRegisterInfo::isVirtualRegister(I->getReg())) { + if (I->isDef()) + Defs.insert(I->getReg()); + else if (I->isKill()) + Kills.insert(I->getReg()); + } + } + } // Update info for all live variables for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) { unsigned Reg = TargetRegisterInfo::index2VirtReg(i); + + // If the Defs is defined in the successor it can't be live in BB. + if (Defs.count(Reg)) + continue; + + // If the register is either killed in or live through SuccBB it's also live + // through BB. VarInfo &VI = getVarInfo(Reg); - if (!VI.AliveBlocks.test(NumNew) && VI.isLiveIn(*SuccBB, Reg, *MRI)) + if (Kills.count(Reg) || VI.AliveBlocks.test(SuccBB->getNumber())) VI.AliveBlocks.set(NumNew); } }