X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FCodeGen%2FMachineBasicBlock.cpp;h=48008537e7546887c6dea064ce2a5ee4c3017b6a;hp=673491608d97c3dbf7875e8d83aa26dc70398319;hb=d04a8d4b33ff316ca4cf961e06c9e312eff8e64f;hpb=ddfd1377d2e4154d44dc3ad217735adc15af2e3f diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp index 673491608d9..48008537e75 100644 --- a/lib/CodeGen/MachineBasicBlock.cpp +++ b/lib/CodeGen/MachineBasicBlock.cpp @@ -12,24 +12,24 @@ //===----------------------------------------------------------------------===// #include "llvm/CodeGen/MachineBasicBlock.h" +#include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/SmallString.h" +#include "llvm/Assembly/Writer.h" #include "llvm/BasicBlock.h" #include "llvm/CodeGen/LiveVariables.h" #include "llvm/CodeGen/MachineDominators.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineLoopInfo.h" #include "llvm/CodeGen/SlotIndexes.h" +#include "llvm/DataLayout.h" #include "llvm/MC/MCAsmInfo.h" #include "llvm/MC/MCContext.h" -#include "llvm/Target/TargetRegisterInfo.h" -#include "llvm/Target/TargetData.h" -#include "llvm/Target/TargetInstrInfo.h" -#include "llvm/Target/TargetMachine.h" -#include "llvm/Assembly/Writer.h" -#include "llvm/ADT/SmallString.h" -#include "llvm/ADT/SmallPtrSet.h" #include "llvm/Support/Debug.h" #include "llvm/Support/LeakDetector.h" #include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetInstrInfo.h" +#include "llvm/Target/TargetMachine.h" +#include "llvm/Target/TargetRegisterInfo.h" #include using namespace llvm; @@ -109,7 +109,8 @@ void ilist_traits::removeNodeFromList(MachineInstr *N) { assert(N->getParent() != 0 && "machine instruction not in a basic block"); // Remove from the use/def lists. - N->RemoveRegOperandsFromUseLists(); + if (MachineFunction *MF = N->getParent()->getParent()) + N->RemoveRegOperandsFromUseLists(MF->getRegInfo()); N->setParent(0); @@ -141,48 +142,50 @@ void ilist_traits::deleteNode(MachineInstr* MI) { } MachineBasicBlock::iterator MachineBasicBlock::getFirstNonPHI() { - instr_iterator I = instr_begin(); - while (I != end() && I->isPHI()) + instr_iterator I = instr_begin(), E = instr_end(); + while (I != E && I->isPHI()) ++I; - assert(!I->isInsideBundle() && "First non-phi MI cannot be inside a bundle!"); + assert((I == E || !I->isInsideBundle()) && + "First non-phi MI cannot be inside a bundle!"); return I; } MachineBasicBlock::iterator MachineBasicBlock::SkipPHIsAndLabels(MachineBasicBlock::iterator I) { - while (I != end() && (I->isPHI() || I->isLabel() || I->isDebugValue())) + iterator E = end(); + while (I != E && (I->isPHI() || I->isLabel() || I->isDebugValue())) ++I; // FIXME: This needs to change if we wish to bundle labels / dbg_values // inside the bundle. - assert(!I->isInsideBundle() && + assert((I == E || !I->isInsideBundle()) && "First non-phi / non-label instruction is inside a bundle!"); return I; } MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() { - iterator I = end(); - while (I != begin() && ((--I)->isTerminator() || I->isDebugValue())) + iterator B = begin(), E = end(), I = E; + while (I != B && ((--I)->isTerminator() || I->isDebugValue())) ; /*noop */ - while (I != end() && !I->isTerminator()) + while (I != E && !I->isTerminator()) ++I; return I; } MachineBasicBlock::const_iterator MachineBasicBlock::getFirstTerminator() const { - const_iterator I = end(); - while (I != begin() && ((--I)->isTerminator() || I->isDebugValue())) + const_iterator B = begin(), E = end(), I = E; + while (I != B && ((--I)->isTerminator() || I->isDebugValue())) ; /*noop */ - while (I != end() && !I->isTerminator()) + while (I != E && !I->isTerminator()) ++I; return I; } MachineBasicBlock::instr_iterator MachineBasicBlock::getFirstInstrTerminator() { - instr_iterator I = instr_end(); - while (I != instr_begin() && ((--I)->isTerminator() || I->isDebugValue())) + instr_iterator B = instr_begin(), E = instr_end(), I = E; + while (I != B && ((--I)->isTerminator() || I->isDebugValue())) ; /*noop */ - while (I != instr_end() && !I->isTerminator()) + while (I != E && !I->isTerminator()) ++I; return I; } @@ -226,9 +229,11 @@ const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const { return 0; } +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void MachineBasicBlock::dump() const { print(dbgs()); } +#endif StringRef MachineBasicBlock::getName() const { if (const BasicBlock *LBB = getBasicBlock()) @@ -237,6 +242,18 @@ StringRef MachineBasicBlock::getName() const { return "(null)"; } +/// Return a hopefully unique identifier for this block. +std::string MachineBasicBlock::getFullName() const { + std::string Name; + if (getParent()) + Name = (getParent()->getName() + ":").str(); + if (getBasicBlock()) + Name += getBasicBlock()->getName(); + else + Name += (Twine("BB") + Twine(getNumber())).str(); + return Name; +} + void MachineBasicBlock::print(raw_ostream &OS, SlotIndexes *Indexes) const { const MachineFunction *MF = getParent(); if (!MF) { @@ -258,11 +275,9 @@ void MachineBasicBlock::print(raw_ostream &OS, SlotIndexes *Indexes) const { } if (isLandingPad()) { OS << Comma << "EH LANDING PAD"; Comma = ", "; } if (hasAddressTaken()) { OS << Comma << "ADDRESS TAKEN"; Comma = ", "; } - if (Alignment) { + if (Alignment) OS << Comma << "Align " << Alignment << " (" << (1u << Alignment) << " bytes)"; - Comma = ", "; - } OS << '\n'; @@ -299,8 +314,11 @@ void MachineBasicBlock::print(raw_ostream &OS, SlotIndexes *Indexes) const { if (!succ_empty()) { if (Indexes) OS << '\t'; OS << " Successors according to CFG:"; - for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI) + for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI) { OS << " BB#" << (*SI)->getNumber(); + if (!Weights.empty()) + OS << '(' << *getWeightIterator(SI) << ')'; + } OS << '\n'; } } @@ -308,8 +326,8 @@ void MachineBasicBlock::print(raw_ostream &OS, SlotIndexes *Indexes) const { void MachineBasicBlock::removeLiveIn(unsigned Reg) { std::vector::iterator I = std::find(LiveIns.begin(), LiveIns.end(), Reg); - assert(I != LiveIns.end() && "Not a live in!"); - LiveIns.erase(I); + if (I != LiveIns.end()) + LiveIns.erase(I); } bool MachineBasicBlock::isLiveIn(unsigned Reg) const { @@ -379,22 +397,44 @@ void MachineBasicBlock::updateTerminator() { TII->InsertBranch(*this, TBB, 0, Cond, dl); } } else { + // Walk through the successors and find the successor which is not + // a landing pad and is not the conditional branch destination (in TBB) + // as the fallthrough successor. + MachineBasicBlock *FallthroughBB = 0; + for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) { + if ((*SI)->isLandingPad() || *SI == TBB) + continue; + assert(!FallthroughBB && "Found more than one fallthrough successor."); + FallthroughBB = *SI; + } + if (!FallthroughBB && canFallThrough()) { + // We fallthrough to the same basic block as the conditional jump + // targets. Remove the conditional jump, leaving unconditional + // fallthrough. + // FIXME: This does not seem like a reasonable pattern to support, but it + // has been seen in the wild coming out of degenerate ARM test cases. + TII->RemoveBranch(*this); + + // Finally update the unconditional successor to be reached via a branch + // if it would not be reached by fallthrough. + if (!isLayoutSuccessor(TBB)) + TII->InsertBranch(*this, TBB, 0, Cond, dl); + return; + } + // The block has a fallthrough conditional branch. - MachineBasicBlock *MBBA = *succ_begin(); - MachineBasicBlock *MBBB = *llvm::next(succ_begin()); - if (MBBA == TBB) std::swap(MBBB, MBBA); if (isLayoutSuccessor(TBB)) { if (TII->ReverseBranchCondition(Cond)) { // We can't reverse the condition, add an unconditional branch. Cond.clear(); - TII->InsertBranch(*this, MBBA, 0, Cond, dl); + TII->InsertBranch(*this, FallthroughBB, 0, Cond, dl); return; } TII->RemoveBranch(*this); - TII->InsertBranch(*this, MBBA, 0, Cond, dl); - } else if (!isLayoutSuccessor(MBBA)) { + TII->InsertBranch(*this, FallthroughBB, 0, Cond, dl); + } else if (!isLayoutSuccessor(FallthroughBB)) { TII->RemoveBranch(*this); - TII->InsertBranch(*this, TBB, MBBA, Cond, dl); + TII->InsertBranch(*this, TBB, FallthroughBB, Cond, dl); } } } @@ -444,18 +484,42 @@ MachineBasicBlock::removeSuccessor(succ_iterator I) { void MachineBasicBlock::replaceSuccessor(MachineBasicBlock *Old, MachineBasicBlock *New) { - uint32_t weight = 0; - succ_iterator SI = std::find(Successors.begin(), Successors.end(), Old); + if (Old == New) + return; - // If Weight list is empty it means we don't use it (disabled optimization). - if (!Weights.empty()) { - weight_iterator WI = getWeightIterator(SI); - weight = *WI; + succ_iterator E = succ_end(); + succ_iterator NewI = E; + succ_iterator OldI = E; + for (succ_iterator I = succ_begin(); I != E; ++I) { + if (*I == Old) { + OldI = I; + if (NewI != E) + break; + } + if (*I == New) { + NewI = I; + if (OldI != E) + break; + } } + assert(OldI != E && "Old is not a successor of this block"); + Old->removePredecessor(this); - // Update the successor information. - removeSuccessor(SI); - addSuccessor(New, weight); + // If New isn't already a successor, let it take Old's place. + if (NewI == E) { + New->addPredecessor(this); + *OldI = New; + return; + } + + // New is already a successor. + // Update its weight instead of adding a duplicate edge. + if (!Weights.empty()) { + weight_iterator OldWI = getWeightIterator(OldI); + *getWeightIterator(NewI) += *OldWI; + Weights.erase(OldWI); + } + Successors.erase(OldI); } void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) { @@ -474,14 +538,13 @@ void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) { while (!fromMBB->succ_empty()) { MachineBasicBlock *Succ = *fromMBB->succ_begin(); - uint32_t weight = 0; - + uint32_t Weight = 0; // If Weight list is empty it means we don't use it (disabled optimization). if (!fromMBB->Weights.empty()) - weight = *fromMBB->Weights.begin(); + Weight = *fromMBB->Weights.begin(); - addSuccessor(Succ, weight); + addSuccessor(Succ, Weight); fromMBB->removeSuccessor(Succ); } } @@ -493,7 +556,10 @@ MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB) { while (!fromMBB->succ_empty()) { MachineBasicBlock *Succ = *fromMBB->succ_begin(); - addSuccessor(Succ); + uint32_t Weight = 0; + if (!fromMBB->Weights.empty()) + Weight = *fromMBB->Weights.begin(); + addSuccessor(Succ, Weight); fromMBB->removeSuccessor(Succ); // Fix up any PHI nodes in the successor. @@ -507,9 +573,12 @@ MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB) { } } +bool MachineBasicBlock::isPredecessor(const MachineBasicBlock *MBB) const { + return std::find(pred_begin(), pred_end(), MBB) != pred_end(); +} + bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const { - const_succ_iterator I = std::find(Successors.begin(), Successors.end(), MBB); - return I != Successors.end(); + return std::find(succ_begin(), succ_end(), MBB) != succ_end(); } bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const { @@ -535,13 +604,10 @@ bool MachineBasicBlock::canFallThrough() { if (TII->AnalyzeBranch(*this, TBB, FBB, Cond)) { // If we couldn't analyze the branch, examine the last instruction. // If the block doesn't end in a known control barrier, assume fallthrough - // is possible. The isPredicable check is needed because this code can be + // is possible. The isPredicated check is needed because this code can be // called during IfConversion, where an instruction which is normally a - // Barrier is predicated and thus no longer an actual control barrier. This - // is over-conservative though, because if an instruction isn't actually - // predicated we could still treat it like a barrier. - return empty() || !back().isBarrier() || - back().isPredicable(); + // Barrier is predicated and thus no longer an actual control barrier. + return empty() || !back().isBarrier() || TII->isPredicated(&back()); } // If there is no branch, control always falls through. @@ -564,6 +630,11 @@ bool MachineBasicBlock::canFallThrough() { MachineBasicBlock * MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) { + // Splitting the critical edge to a landing pad block is non-trivial. Don't do + // it in this generic function. + if (Succ->isLandingPad()) + return NULL; + MachineFunction *MF = getParent(); DebugLoc dl; // FIXME: this is nowhere @@ -605,10 +676,11 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) { MachineInstr *MI = I; for (MachineInstr::mop_iterator OI = MI->operands_begin(), OE = MI->operands_end(); OI != OE; ++OI) { - if (!OI->isReg() || !OI->isUse() || !OI->isKill() || OI->isUndef()) + if (!OI->isReg() || OI->getReg() == 0 || + !OI->isUse() || !OI->isKill() || OI->isUndef()) continue; unsigned Reg = OI->getReg(); - if (TargetRegisterInfo::isVirtualRegister(Reg) && + if (TargetRegisterInfo::isPhysicalRegister(Reg) || LV->getVarInfo(Reg).removeKill(MI)) { KilledRegs.push_back(Reg); DEBUG(dbgs() << "Removing terminator kill: " << *MI); @@ -637,18 +709,20 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) { // Inherit live-ins from the successor for (MachineBasicBlock::livein_iterator I = Succ->livein_begin(), - E = Succ->livein_end(); I != E; ++I) + E = Succ->livein_end(); I != E; ++I) NMBB->addLiveIn(*I); // Update LiveVariables. + const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo(); if (LV) { // Restore kills of virtual registers that were killed by the terminators. while (!KilledRegs.empty()) { unsigned Reg = KilledRegs.pop_back_val(); for (instr_iterator I = instr_end(), E = instr_begin(); I != E;) { - if (!(--I)->addRegisterKilled(Reg, NULL, /* addIfNotFound= */ false)) + if (!(--I)->addRegisterKilled(Reg, TRI, /* addIfNotFound= */ false)) continue; - LV->getVarInfo(Reg).Kills.push_back(I); + if (TargetRegisterInfo::isVirtualRegister(Reg)) + LV->getVarInfo(Reg).Kills.push_back(I); DEBUG(dbgs() << "Restored terminator kill: " << *I); break; } @@ -726,8 +800,9 @@ MachineBasicBlock::erase(MachineBasicBlock::iterator I) { MachineInstr *MachineBasicBlock::remove(MachineInstr *I) { if (I->isBundle()) { - MachineBasicBlock::instr_iterator MII = I; ++MII; - while (MII != end() && MII->isInsideBundle()) { + instr_iterator MII = llvm::next(I); + iterator E = end(); + while (MII != E && MII->isInsideBundle()) { MachineInstr *MI = &*MII++; Insts.remove(MI); } @@ -870,12 +945,11 @@ MachineBasicBlock::findDebugLoc(instr_iterator MBBI) { /// getSuccWeight - Return weight of the edge from this block to MBB. /// -uint32_t MachineBasicBlock::getSuccWeight(MachineBasicBlock *succ) { +uint32_t MachineBasicBlock::getSuccWeight(const_succ_iterator Succ) const { if (Weights.empty()) return 0; - succ_iterator I = std::find(Successors.begin(), Successors.end(), succ); - return *getWeightIterator(I); + return *getWeightIterator(Succ); } /// getWeightIterator - Return wight iterator corresonding to the I successor @@ -888,6 +962,93 @@ getWeightIterator(MachineBasicBlock::succ_iterator I) { return Weights.begin() + index; } +/// getWeightIterator - Return wight iterator corresonding to the I successor +/// iterator +MachineBasicBlock::const_weight_iterator MachineBasicBlock:: +getWeightIterator(MachineBasicBlock::const_succ_iterator I) const { + assert(Weights.size() == Successors.size() && "Async weight list!"); + const size_t index = std::distance(Successors.begin(), I); + assert(index < Weights.size() && "Not a current successor!"); + return Weights.begin() + index; +} + +/// Return whether (physical) register "Reg" has been ined and not ed +/// as of just before "MI". +/// +/// Search is localised to a neighborhood of +/// Neighborhood instructions before (searching for defs or kills) and N +/// instructions after (searching just for defs) MI. +MachineBasicBlock::LivenessQueryResult +MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI, + unsigned Reg, MachineInstr *MI, + unsigned Neighborhood) { + unsigned N = Neighborhood; + MachineBasicBlock *MBB = MI->getParent(); + + // Start by searching backwards from MI, looking for kills, reads or defs. + + MachineBasicBlock::iterator I(MI); + // If this is the first insn in the block, don't search backwards. + if (I != MBB->begin()) { + do { + --I; + + MachineOperandIteratorBase::PhysRegInfo Analysis = + MIOperands(I).analyzePhysReg(Reg, TRI); + + if (Analysis.Defines) + // Outputs happen after inputs so they take precedence if both are + // present. + return Analysis.DefinesDead ? LQR_Dead : LQR_Live; + + if (Analysis.Kills || Analysis.Clobbers) + // Register killed, so isn't live. + return LQR_Dead; + + else if (Analysis.ReadsOverlap) + // Defined or read without a previous kill - live. + return Analysis.Reads ? LQR_Live : LQR_OverlappingLive; + + } while (I != MBB->begin() && --N > 0); + } + + // Did we get to the start of the block? + if (I == MBB->begin()) { + // If so, the register's state is definitely defined by the live-in state. + for (MCRegAliasIterator RAI(Reg, TRI, /*IncludeSelf=*/true); + RAI.isValid(); ++RAI) { + if (MBB->isLiveIn(*RAI)) + return (*RAI == Reg) ? LQR_Live : LQR_OverlappingLive; + } + + return LQR_Dead; + } + + N = Neighborhood; + + // Try searching forwards from MI, looking for reads or defs. + I = MachineBasicBlock::iterator(MI); + // If this is the last insn in the block, don't search forwards. + if (I != MBB->end()) { + for (++I; I != MBB->end() && N > 0; ++I, --N) { + MachineOperandIteratorBase::PhysRegInfo Analysis = + MIOperands(I).analyzePhysReg(Reg, TRI); + + if (Analysis.ReadsOverlap) + // Used, therefore must have been live. + return (Analysis.Reads) ? + LQR_Live : LQR_OverlappingLive; + + else if (Analysis.Clobbers || Analysis.Defines) + // Defined (but not read) therefore cannot have been live. + return LQR_Dead; + } + } + + // At this point we have no idea of the liveness of the register. + return LQR_Unknown; +} + void llvm::WriteAsOperand(raw_ostream &OS, const MachineBasicBlock *MBB, bool t) { OS << "BB#" << MBB->getNumber();