//===- ExecutionDepsFix.cpp - Fix execution dependecy issues ----*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file contains the execution dependency fix pass. // // Some X86 SSE instructions like mov, and, or, xor are available in different // variants for different operand types. These variant instructions are // equivalent, but on Nehalem and newer cpus there is extra latency // transferring data between integer and floating point domains. ARM cores // have similar issues when they are configured with both VFP and NEON // pipelines. // // This pass changes the variant instructions to minimize domain crossings. // //===----------------------------------------------------------------------===// #include "llvm/CodeGen/Passes.h" #include "llvm/ADT/PostOrderIterator.h" #include "llvm/CodeGen/LivePhysRegs.h" #include "llvm/CodeGen/MachineFunctionPass.h" #include "llvm/CodeGen/MachineRegisterInfo.h" #include "llvm/Support/Allocator.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Target/TargetInstrInfo.h" #include "llvm/Target/TargetMachine.h" using namespace llvm; #define DEBUG_TYPE "execution-fix" /// A DomainValue is a bit like LiveIntervals' ValNo, but it also keeps track /// of execution domains. /// /// An open DomainValue represents a set of instructions that can still switch /// execution domain. Multiple registers may refer to the same open /// DomainValue - they will eventually be collapsed to the same execution /// domain. /// /// A collapsed DomainValue represents a single register that has been forced /// into one of more execution domains. There is a separate collapsed /// DomainValue for each register, but it may contain multiple execution /// domains. A register value is initially created in a single execution /// domain, but if we were forced to pay the penalty of a domain crossing, we /// keep track of the fact that the register is now available in multiple /// domains. namespace { struct DomainValue { // Basic reference counting. unsigned Refs; // Bitmask of available domains. For an open DomainValue, it is the still // possible domains for collapsing. For a collapsed DomainValue it is the // domains where the register is available for free. unsigned AvailableDomains; // Pointer to the next DomainValue in a chain. When two DomainValues are // merged, Victim.Next is set to point to Victor, so old DomainValue // references can be updated by following the chain. DomainValue *Next; // Twiddleable instructions using or defining these registers. SmallVector Instrs; // A collapsed DomainValue has no instructions to twiddle - it simply keeps // track of the domains where the registers are already available. bool isCollapsed() const { return Instrs.empty(); } // Is domain available? bool hasDomain(unsigned domain) const { return AvailableDomains & (1u << domain); } // Mark domain as available. void addDomain(unsigned domain) { AvailableDomains |= 1u << domain; } // Restrict to a single domain available. void setSingleDomain(unsigned domain) { AvailableDomains = 1u << domain; } // Return bitmask of domains that are available and in mask. unsigned getCommonDomains(unsigned mask) const { return AvailableDomains & mask; } // First domain available. unsigned getFirstDomain() const { return countTrailingZeros(AvailableDomains); } DomainValue() : Refs(0) { clear(); } // Clear this DomainValue and point to next which has all its data. void clear() { AvailableDomains = 0; Next = nullptr; Instrs.clear(); } }; } namespace { /// LiveReg - Information about a live register. struct LiveReg { /// Value currently in this register, or NULL when no value is being tracked. /// This counts as a DomainValue reference. DomainValue *Value; /// Instruction that defined this register, relative to the beginning of the /// current basic block. When a LiveReg is used to represent a live-out /// register, this value is relative to the end of the basic block, so it /// will be a negative number. int Def; }; } // anonynous namespace namespace { class ExeDepsFix : public MachineFunctionPass { static char ID; SpecificBumpPtrAllocator Allocator; SmallVector Avail; const TargetRegisterClass *const RC; MachineFunction *MF; const TargetInstrInfo *TII; const TargetRegisterInfo *TRI; std::vector AliasMap; const unsigned NumRegs; LiveReg *LiveRegs; typedef DenseMap LiveOutMap; LiveOutMap LiveOuts; /// List of undefined register reads in this block in forward order. std::vector > UndefReads; /// Storage for register unit liveness. LivePhysRegs LiveRegSet; /// Current instruction number. /// The first instruction in each basic block is 0. int CurInstr; /// True when the current block has a predecessor that hasn't been visited /// yet. bool SeenUnknownBackEdge; public: ExeDepsFix(const TargetRegisterClass *rc) : MachineFunctionPass(ID), RC(rc), NumRegs(RC->getNumRegs()) {} void getAnalysisUsage(AnalysisUsage &AU) const override { AU.setPreservesAll(); MachineFunctionPass::getAnalysisUsage(AU); } bool runOnMachineFunction(MachineFunction &MF) override; const char *getPassName() const override { return "Execution dependency fix"; } private: // Register mapping. int regIndex(unsigned Reg); // DomainValue allocation. DomainValue *alloc(int domain = -1); DomainValue *retain(DomainValue *DV) { if (DV) ++DV->Refs; return DV; } void release(DomainValue*); DomainValue *resolve(DomainValue*&); // LiveRegs manipulations. void setLiveReg(int rx, DomainValue *DV); void kill(int rx); void force(int rx, unsigned domain); void collapse(DomainValue *dv, unsigned domain); bool merge(DomainValue *A, DomainValue *B); void enterBasicBlock(MachineBasicBlock*); void leaveBasicBlock(MachineBasicBlock*); void visitInstr(MachineInstr*); void processDefs(MachineInstr*, bool Kill); void visitSoftInstr(MachineInstr*, unsigned mask); void visitHardInstr(MachineInstr*, unsigned domain); bool shouldBreakDependence(MachineInstr*, unsigned OpIdx, unsigned Pref); void processUndefReads(MachineBasicBlock*); }; } char ExeDepsFix::ID = 0; /// Translate TRI register number to an index into our smaller tables of /// interesting registers. Return -1 for boring registers. int ExeDepsFix::regIndex(unsigned Reg) { assert(Reg < AliasMap.size() && "Invalid register"); return AliasMap[Reg]; } DomainValue *ExeDepsFix::alloc(int domain) { DomainValue *dv = Avail.empty() ? new(Allocator.Allocate()) DomainValue : Avail.pop_back_val(); if (domain >= 0) dv->addDomain(domain); assert(dv->Refs == 0 && "Reference count wasn't cleared"); assert(!dv->Next && "Chained DomainValue shouldn't have been recycled"); return dv; } /// release - Release a reference to DV. When the last reference is released, /// collapse if needed. void ExeDepsFix::release(DomainValue *DV) { while (DV) { assert(DV->Refs && "Bad DomainValue"); if (--DV->Refs) return; // There are no more DV references. Collapse any contained instructions. if (DV->AvailableDomains && !DV->isCollapsed()) collapse(DV, DV->getFirstDomain()); DomainValue *Next = DV->Next; DV->clear(); Avail.push_back(DV); // Also release the next DomainValue in the chain. DV = Next; } } /// resolve - Follow the chain of dead DomainValues until a live DomainValue is /// reached. Update the referenced pointer when necessary. DomainValue *ExeDepsFix::resolve(DomainValue *&DVRef) { DomainValue *DV = DVRef; if (!DV || !DV->Next) return DV; // DV has a chain. Find the end. do DV = DV->Next; while (DV->Next); // Update DVRef to point to DV. retain(DV); release(DVRef); DVRef = DV; return DV; } /// Set LiveRegs[rx] = dv, updating reference counts. void ExeDepsFix::setLiveReg(int rx, DomainValue *dv) { assert(unsigned(rx) < NumRegs && "Invalid index"); assert(LiveRegs && "Must enter basic block first."); if (LiveRegs[rx].Value == dv) return; if (LiveRegs[rx].Value) release(LiveRegs[rx].Value); LiveRegs[rx].Value = retain(dv); } // Kill register rx, recycle or collapse any DomainValue. void ExeDepsFix::kill(int rx) { assert(unsigned(rx) < NumRegs && "Invalid index"); assert(LiveRegs && "Must enter basic block first."); if (!LiveRegs[rx].Value) return; release(LiveRegs[rx].Value); LiveRegs[rx].Value = nullptr; } /// Force register rx into domain. void ExeDepsFix::force(int rx, unsigned domain) { assert(unsigned(rx) < NumRegs && "Invalid index"); assert(LiveRegs && "Must enter basic block first."); if (DomainValue *dv = LiveRegs[rx].Value) { if (dv->isCollapsed()) dv->addDomain(domain); else if (dv->hasDomain(domain)) collapse(dv, domain); else { // This is an incompatible open DomainValue. Collapse it to whatever and // force the new value into domain. This costs a domain crossing. collapse(dv, dv->getFirstDomain()); assert(LiveRegs[rx].Value && "Not live after collapse?"); LiveRegs[rx].Value->addDomain(domain); } } else { // Set up basic collapsed DomainValue. setLiveReg(rx, alloc(domain)); } } /// Collapse open DomainValue into given domain. If there are multiple /// registers using dv, they each get a unique collapsed DomainValue. void ExeDepsFix::collapse(DomainValue *dv, unsigned domain) { assert(dv->hasDomain(domain) && "Cannot collapse"); // Collapse all the instructions. while (!dv->Instrs.empty()) TII->setExecutionDomain(dv->Instrs.pop_back_val(), domain); dv->setSingleDomain(domain); // If there are multiple users, give them new, unique DomainValues. if (LiveRegs && dv->Refs > 1) for (unsigned rx = 0; rx != NumRegs; ++rx) if (LiveRegs[rx].Value == dv) setLiveReg(rx, alloc(domain)); } /// Merge - All instructions and registers in B are moved to A, and B is /// released. bool ExeDepsFix::merge(DomainValue *A, DomainValue *B) { assert(!A->isCollapsed() && "Cannot merge into collapsed"); assert(!B->isCollapsed() && "Cannot merge from collapsed"); if (A == B) return true; // Restrict to the domains that A and B have in common. unsigned common = A->getCommonDomains(B->AvailableDomains); if (!common) return false; A->AvailableDomains = common; A->Instrs.append(B->Instrs.begin(), B->Instrs.end()); // Clear the old DomainValue so we won't try to swizzle instructions twice. B->clear(); // All uses of B are referred to A. B->Next = retain(A); for (unsigned rx = 0; rx != NumRegs; ++rx) if (LiveRegs[rx].Value == B) setLiveReg(rx, A); return true; } // enterBasicBlock - Set up LiveRegs by merging predecessor live-out values. void ExeDepsFix::enterBasicBlock(MachineBasicBlock *MBB) { // Detect back-edges from predecessors we haven't processed yet. SeenUnknownBackEdge = false; // Reset instruction counter in each basic block. CurInstr = 0; // Set up UndefReads to track undefined register reads. UndefReads.clear(); LiveRegSet.clear(); // Set up LiveRegs to represent registers entering MBB. if (!LiveRegs) LiveRegs = new LiveReg[NumRegs]; // Default values are 'nothing happened a long time ago'. for (unsigned rx = 0; rx != NumRegs; ++rx) { LiveRegs[rx].Value = nullptr; LiveRegs[rx].Def = -(1 << 20); } // This is the entry block. if (MBB->pred_empty()) { for (MachineBasicBlock::livein_iterator i = MBB->livein_begin(), e = MBB->livein_end(); i != e; ++i) { int rx = regIndex(*i); if (rx < 0) continue; // Treat function live-ins as if they were defined just before the first // instruction. Usually, function arguments are set up immediately // before the call. LiveRegs[rx].Def = -1; } DEBUG(dbgs() << "BB#" << MBB->getNumber() << ": entry\n"); return; } // Try to coalesce live-out registers from predecessors. for (MachineBasicBlock::const_pred_iterator pi = MBB->pred_begin(), pe = MBB->pred_end(); pi != pe; ++pi) { LiveOutMap::const_iterator fi = LiveOuts.find(*pi); if (fi == LiveOuts.end()) { SeenUnknownBackEdge = true; continue; } assert(fi->second && "Can't have NULL entries"); for (unsigned rx = 0; rx != NumRegs; ++rx) { // Use the most recent predecessor def for each register. LiveRegs[rx].Def = std::max(LiveRegs[rx].Def, fi->second[rx].Def); DomainValue *pdv = resolve(fi->second[rx].Value); if (!pdv) continue; if (!LiveRegs[rx].Value) { setLiveReg(rx, pdv); continue; } // We have a live DomainValue from more than one predecessor. if (LiveRegs[rx].Value->isCollapsed()) { // We are already collapsed, but predecessor is not. Force him. unsigned Domain = LiveRegs[rx].Value->getFirstDomain(); if (!pdv->isCollapsed() && pdv->hasDomain(Domain)) collapse(pdv, Domain); continue; } // Currently open, merge in predecessor. if (!pdv->isCollapsed()) merge(LiveRegs[rx].Value, pdv); else force(rx, pdv->getFirstDomain()); } } DEBUG(dbgs() << "BB#" << MBB->getNumber() << (SeenUnknownBackEdge ? ": incomplete\n" : ": all preds known\n")); } void ExeDepsFix::leaveBasicBlock(MachineBasicBlock *MBB) { assert(LiveRegs && "Must enter basic block first."); // Save live registers at end of MBB - used by enterBasicBlock(). // Also use LiveOuts as a visited set to detect back-edges. bool First = LiveOuts.insert(std::make_pair(MBB, LiveRegs)).second; if (First) { // LiveRegs was inserted in LiveOuts. Adjust all defs to be relative to // the end of this block instead of the beginning. for (unsigned i = 0, e = NumRegs; i != e; ++i) LiveRegs[i].Def -= CurInstr; } else { // Insertion failed, this must be the second pass. // Release all the DomainValues instead of keeping them. for (unsigned i = 0, e = NumRegs; i != e; ++i) release(LiveRegs[i].Value); delete[] LiveRegs; } LiveRegs = nullptr; } void ExeDepsFix::visitInstr(MachineInstr *MI) { if (MI->isDebugValue()) return; // Update instructions with explicit execution domains. std::pair DomP = TII->getExecutionDomain(MI); if (DomP.first) { if (DomP.second) visitSoftInstr(MI, DomP.second); else visitHardInstr(MI, DomP.first); } // Process defs to track register ages, and kill values clobbered by generic // instructions. processDefs(MI, !DomP.first); } /// \brief Return true to if it makes sense to break dependence on a partial def /// or undef use. bool ExeDepsFix::shouldBreakDependence(MachineInstr *MI, unsigned OpIdx, unsigned Pref) { int rx = regIndex(MI->getOperand(OpIdx).getReg()); if (rx < 0) return false; unsigned Clearance = CurInstr - LiveRegs[rx].Def; DEBUG(dbgs() << "Clearance: " << Clearance << ", want " << Pref); if (Pref > Clearance) { DEBUG(dbgs() << ": Break dependency.\n"); return true; } // The current clearance seems OK, but we may be ignoring a def from a // back-edge. if (!SeenUnknownBackEdge || Pref <= unsigned(CurInstr)) { DEBUG(dbgs() << ": OK .\n"); return false; } // A def from an unprocessed back-edge may make us break this dependency. DEBUG(dbgs() << ": Wait for back-edge to resolve.\n"); return false; } // Update def-ages for registers defined by MI. // If Kill is set, also kill off DomainValues clobbered by the defs. // // Also break dependencies on partial defs and undef uses. void ExeDepsFix::processDefs(MachineInstr *MI, bool Kill) { assert(!MI->isDebugValue() && "Won't process debug values"); // Break dependence on undef uses. Do this before updating LiveRegs below. unsigned OpNum; unsigned Pref = TII->getUndefRegClearance(MI, OpNum, TRI); if (Pref) { if (shouldBreakDependence(MI, OpNum, Pref)) UndefReads.push_back(std::make_pair(MI, OpNum)); } const MCInstrDesc &MCID = MI->getDesc(); for (unsigned i = 0, e = MI->isVariadic() ? MI->getNumOperands() : MCID.getNumDefs(); i != e; ++i) { MachineOperand &MO = MI->getOperand(i); if (!MO.isReg()) continue; if (MO.isImplicit()) break; if (MO.isUse()) continue; int rx = regIndex(MO.getReg()); if (rx < 0) continue; // This instruction explicitly defines rx. DEBUG(dbgs() << TRI->getName(RC->getRegister(rx)) << ":\t" << CurInstr << '\t' << *MI); // Check clearance before partial register updates. // Call breakDependence before setting LiveRegs[rx].Def. unsigned Pref = TII->getPartialRegUpdateClearance(MI, i, TRI); if (Pref && shouldBreakDependence(MI, i, Pref)) TII->breakPartialRegDependency(MI, i, TRI); // How many instructions since rx was last written? LiveRegs[rx].Def = CurInstr; // Kill off domains redefined by generic instructions. if (Kill) kill(rx); } ++CurInstr; } /// \break Break false dependencies on undefined register reads. /// /// Walk the block backward computing precise liveness. This is expensive, so we /// only do it on demand. Note that the occurrence of undefined register reads /// that should be broken is very rare, but when they occur we may have many in /// a single block. void ExeDepsFix::processUndefReads(MachineBasicBlock *MBB) { if (UndefReads.empty()) return; // Collect this block's live out register units. LiveRegSet.init(TRI); LiveRegSet.addLiveOuts(MBB); MachineInstr *UndefMI = UndefReads.back().first; unsigned OpIdx = UndefReads.back().second; for (MachineBasicBlock::reverse_iterator I = MBB->rbegin(), E = MBB->rend(); I != E; ++I) { // Update liveness, including the current instruction's defs. LiveRegSet.stepBackward(*I); if (UndefMI == &*I) { if (!LiveRegSet.contains(UndefMI->getOperand(OpIdx).getReg())) TII->breakPartialRegDependency(UndefMI, OpIdx, TRI); UndefReads.pop_back(); if (UndefReads.empty()) return; UndefMI = UndefReads.back().first; OpIdx = UndefReads.back().second; } } } // A hard instruction only works in one domain. All input registers will be // forced into that domain. void ExeDepsFix::visitHardInstr(MachineInstr *mi, unsigned domain) { // Collapse all uses. for (unsigned i = mi->getDesc().getNumDefs(), e = mi->getDesc().getNumOperands(); i != e; ++i) { MachineOperand &mo = mi->getOperand(i); if (!mo.isReg()) continue; int rx = regIndex(mo.getReg()); if (rx < 0) continue; force(rx, domain); } // Kill all defs and force them. for (unsigned i = 0, e = mi->getDesc().getNumDefs(); i != e; ++i) { MachineOperand &mo = mi->getOperand(i); if (!mo.isReg()) continue; int rx = regIndex(mo.getReg()); if (rx < 0) continue; kill(rx); force(rx, domain); } } // A soft instruction can be changed to work in other domains given by mask. void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) { // Bitmask of available domains for this instruction after taking collapsed // operands into account. unsigned available = mask; // Scan the explicit use operands for incoming domains. SmallVector used; if (LiveRegs) for (unsigned i = mi->getDesc().getNumDefs(), e = mi->getDesc().getNumOperands(); i != e; ++i) { MachineOperand &mo = mi->getOperand(i); if (!mo.isReg()) continue; int rx = regIndex(mo.getReg()); if (rx < 0) continue; if (DomainValue *dv = LiveRegs[rx].Value) { // Bitmask of domains that dv and available have in common. unsigned common = dv->getCommonDomains(available); // Is it possible to use this collapsed register for free? if (dv->isCollapsed()) { // Restrict available domains to the ones in common with the operand. // If there are no common domains, we must pay the cross-domain // penalty for this operand. if (common) available = common; } else if (common) // Open DomainValue is compatible, save it for merging. used.push_back(rx); else // Open DomainValue is not compatible with instruction. It is useless // now. kill(rx); } } // If the collapsed operands force a single domain, propagate the collapse. if (isPowerOf2_32(available)) { unsigned domain = countTrailingZeros(available); TII->setExecutionDomain(mi, domain); visitHardInstr(mi, domain); return; } // Kill off any remaining uses that don't match available, and build a list of // incoming DomainValues that we want to merge. SmallVector Regs; for (SmallVectorImpl::iterator i=used.begin(), e=used.end(); i!=e; ++i) { int rx = *i; const LiveReg &LR = LiveRegs[rx]; // This useless DomainValue could have been missed above. if (!LR.Value->getCommonDomains(available)) { kill(rx); continue; } // Sorted insertion. bool Inserted = false; for (SmallVectorImpl::iterator i = Regs.begin(), e = Regs.end(); i != e && !Inserted; ++i) { if (LR.Def < i->Def) { Inserted = true; Regs.insert(i, LR); } } if (!Inserted) Regs.push_back(LR); } // doms are now sorted in order of appearance. Try to merge them all, giving // priority to the latest ones. DomainValue *dv = nullptr; while (!Regs.empty()) { if (!dv) { dv = Regs.pop_back_val().Value; // Force the first dv to match the current instruction. dv->AvailableDomains = dv->getCommonDomains(available); assert(dv->AvailableDomains && "Domain should have been filtered"); continue; } DomainValue *Latest = Regs.pop_back_val().Value; // Skip already merged values. if (Latest == dv || Latest->Next) continue; if (merge(dv, Latest)) continue; // If latest didn't merge, it is useless now. Kill all registers using it. for (SmallVectorImpl::iterator i=used.begin(), e=used.end(); i!=e; ++i) if (LiveRegs[*i].Value == Latest) kill(*i); } // dv is the DomainValue we are going to use for this instruction. if (!dv) { dv = alloc(); dv->AvailableDomains = available; } dv->Instrs.push_back(mi); // Finally set all defs and non-collapsed uses to dv. We must iterate through // all the operators, including imp-def ones. for (MachineInstr::mop_iterator ii = mi->operands_begin(), ee = mi->operands_end(); ii != ee; ++ii) { MachineOperand &mo = *ii; if (!mo.isReg()) continue; int rx = regIndex(mo.getReg()); if (rx < 0) continue; if (!LiveRegs[rx].Value || (mo.isDef() && LiveRegs[rx].Value != dv)) { kill(rx); setLiveReg(rx, dv); } } } bool ExeDepsFix::runOnMachineFunction(MachineFunction &mf) { MF = &mf; TII = MF->getTarget().getInstrInfo(); TRI = MF->getTarget().getRegisterInfo(); LiveRegs = nullptr; assert(NumRegs == RC->getNumRegs() && "Bad regclass"); DEBUG(dbgs() << "********** FIX EXECUTION DEPENDENCIES: " << RC->getName() << " **********\n"); // If no relevant registers are used in the function, we can skip it // completely. bool anyregs = false; for (TargetRegisterClass::const_iterator I = RC->begin(), E = RC->end(); I != E; ++I) if (MF->getRegInfo().isPhysRegUsed(*I)) { anyregs = true; break; } if (!anyregs) return false; // Initialize the AliasMap on the first use. if (AliasMap.empty()) { // Given a PhysReg, AliasMap[PhysReg] is either the relevant index into RC, // or -1. AliasMap.resize(TRI->getNumRegs(), -1); for (unsigned i = 0, e = RC->getNumRegs(); i != e; ++i) for (MCRegAliasIterator AI(RC->getRegister(i), TRI, true); AI.isValid(); ++AI) AliasMap[*AI] = i; } MachineBasicBlock *Entry = MF->begin(); ReversePostOrderTraversal RPOT(Entry); SmallVector Loops; for (ReversePostOrderTraversal::rpo_iterator MBBI = RPOT.begin(), MBBE = RPOT.end(); MBBI != MBBE; ++MBBI) { MachineBasicBlock *MBB = *MBBI; enterBasicBlock(MBB); if (SeenUnknownBackEdge) Loops.push_back(MBB); for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E; ++I) visitInstr(I); processUndefReads(MBB); leaveBasicBlock(MBB); } // Visit all the loop blocks again in order to merge DomainValues from // back-edges. for (unsigned i = 0, e = Loops.size(); i != e; ++i) { MachineBasicBlock *MBB = Loops[i]; enterBasicBlock(MBB); for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E; ++I) if (!I->isDebugValue()) processDefs(I, false); processUndefReads(MBB); leaveBasicBlock(MBB); } // Clear the LiveOuts vectors and collapse any remaining DomainValues. for (ReversePostOrderTraversal::rpo_iterator MBBI = RPOT.begin(), MBBE = RPOT.end(); MBBI != MBBE; ++MBBI) { LiveOutMap::const_iterator FI = LiveOuts.find(*MBBI); if (FI == LiveOuts.end() || !FI->second) continue; for (unsigned i = 0, e = NumRegs; i != e; ++i) if (FI->second[i].Value) release(FI->second[i].Value); delete[] FI->second; } LiveOuts.clear(); UndefReads.clear(); Avail.clear(); Allocator.DestroyAll(); return false; } FunctionPass * llvm::createExecutionDependencyFixPass(const TargetRegisterClass *RC) { return new ExeDepsFix(RC); }