X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FMachineBasicBlock.cpp;h=6ade6a85e53573751cacd450e8468f2195811b42;hb=3e2d76c946ba753c2b11af192a52e25b6f9b46ff;hp=611b045691468067bce641d78c610d90815a735d;hpb=f378f5fae3b7c35fc0f8996accf121ffe59093e2;p=oota-llvm.git diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp index 611b0456914..6ade6a85e53 100644 --- a/lib/CodeGen/MachineBasicBlock.cpp +++ b/lib/CodeGen/MachineBasicBlock.cpp @@ -21,7 +21,7 @@ #include "llvm/MC/MCAsmInfo.h" #include "llvm/MC/MCContext.h" #include "llvm/Target/TargetRegisterInfo.h" -#include "llvm/Target/TargetData.h" +#include "llvm/DataLayout.h" #include "llvm/Target/TargetInstrInfo.h" #include "llvm/Target/TargetMachine.h" #include "llvm/Assembly/Writer.h" @@ -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); @@ -227,9 +228,11 @@ 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()) @@ -238,6 +241,18 @@ 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) { @@ -259,11 +274,9 @@ 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'; @@ -300,8 +313,11 @@ 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'; } } @@ -309,8 +325,8 @@ 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 { @@ -380,22 +396,44 @@ 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); } } } @@ -445,18 +483,42 @@ 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) { @@ -475,14 +537,13 @@ 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); } } @@ -494,7 +555,10 @@ 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. @@ -508,9 +572,12 @@ 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 { @@ -562,6 +629,11 @@ 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 @@ -636,7 +708,7 @@ 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. @@ -872,12 +944,11 @@ MachineBasicBlock::findDebugLoc(instr_iterator MBBI) { /// getSuccWeight - Return weight of the edge from this block to MBB. /// -uint32_t MachineBasicBlock::getSuccWeight(const MachineBasicBlock *succ) const { +uint32_t MachineBasicBlock::getSuccWeight(const_succ_iterator Succ) const { if (Weights.empty()) return 0; - const_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 @@ -900,6 +971,80 @@ getWeightIterator(MachineBasicBlock::const_succ_iterator I) const { 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.Kills) + // Register killed, so isn't live. + return LQR_Dead; + + else if (Analysis.DefinesOverlap || Analysis.ReadsOverlap) + // Defined or read without a previous kill - live. + return (Analysis.Defines || 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.DefinesOverlap) + // 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();