//===- HexagonPacketizer.cpp - VLIW packetizer ----------------------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This implements a simple VLIW packetizer using DFA. The packetizer works on // machine basic blocks. For each instruction I in BB, the packetizer consults // the DFA to see if machine resources are available to execute I. If so, the // packetizer checks if I depends on any instruction J in the current packet. // If no dependency is found, I is added to current packet and machine resource // is marked as taken. If any dependency is found, a target API call is made to // prune the dependence. // //===----------------------------------------------------------------------===// #include "HexagonVLIWPacketizer.h" #include "Hexagon.h" #include "HexagonInstrInfo.h" #include "HexagonRegisterInfo.h" #include "HexagonSubtarget.h" #include "llvm/ADT/BitVector.h" #include "llvm/ADT/DenseSet.h" #include "llvm/ADT/STLExtras.h" #include "llvm/Analysis/AliasAnalysis.h" #include "llvm/CodeGen/MachineBasicBlock.h" #include "llvm/CodeGen/MachineBranchProbabilityInfo.h" #include "llvm/CodeGen/MachineDominators.h" #include "llvm/CodeGen/MachineFrameInfo.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineFunctionPass.h" #include "llvm/CodeGen/MachineInstr.h" #include "llvm/CodeGen/MachineInstrBundle.h" #include "llvm/CodeGen/MachineLoopInfo.h" #include "llvm/CodeGen/MachineOperand.h" #include "llvm/CodeGen/ScheduleDAG.h" #include "llvm/CodeGen/TargetRegisterInfo.h" #include "llvm/CodeGen/TargetSubtargetInfo.h" #include "llvm/IR/DebugLoc.h" #include "llvm/MC/MCInstrDesc.h" #include "llvm/Pass.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" #include #include #include using namespace llvm; #define DEBUG_TYPE "packets" static cl::opt DisablePacketizer("disable-packetizer", cl::Hidden, cl::ZeroOrMore, cl::init(false), cl::desc("Disable Hexagon packetizer pass")); cl::opt Slot1Store("slot1-store-slot0-load", cl::Hidden, cl::ZeroOrMore, cl::init(true), cl::desc("Allow slot1 store and slot0 load")); static cl::opt PacketizeVolatiles("hexagon-packetize-volatiles", cl::ZeroOrMore, cl::Hidden, cl::init(true), cl::desc("Allow non-solo packetization of volatile memory references")); static cl::opt EnableGenAllInsnClass("enable-gen-insn", cl::init(false), cl::Hidden, cl::ZeroOrMore, cl::desc("Generate all instruction with TC")); static cl::opt DisableVecDblNVStores("disable-vecdbl-nv-stores", cl::init(false), cl::Hidden, cl::ZeroOrMore, cl::desc("Disable vector double new-value-stores")); extern cl::opt ScheduleInlineAsm; namespace llvm { FunctionPass *createHexagonPacketizer(bool Minimal); void initializeHexagonPacketizerPass(PassRegistry&); } // end namespace llvm namespace { class HexagonPacketizer : public MachineFunctionPass { public: static char ID; HexagonPacketizer(bool Min = false) : MachineFunctionPass(ID), Minimal(Min) {} void getAnalysisUsage(AnalysisUsage &AU) const override { AU.setPreservesCFG(); AU.addRequired(); AU.addRequired(); AU.addRequired(); AU.addRequired(); AU.addPreserved(); AU.addPreserved(); MachineFunctionPass::getAnalysisUsage(AU); } StringRef getPassName() const override { return "Hexagon Packetizer"; } bool runOnMachineFunction(MachineFunction &Fn) override; MachineFunctionProperties getRequiredProperties() const override { return MachineFunctionProperties().set( MachineFunctionProperties::Property::NoVRegs); } private: const HexagonInstrInfo *HII; const HexagonRegisterInfo *HRI; const bool Minimal; }; } // end anonymous namespace char HexagonPacketizer::ID = 0; INITIALIZE_PASS_BEGIN(HexagonPacketizer, "hexagon-packetizer", "Hexagon Packetizer", false, false) INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree) INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo) INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo) INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass) INITIALIZE_PASS_END(HexagonPacketizer, "hexagon-packetizer", "Hexagon Packetizer", false, false) HexagonPacketizerList::HexagonPacketizerList(MachineFunction &MF, MachineLoopInfo &MLI, AliasAnalysis *AA, const MachineBranchProbabilityInfo *MBPI, bool Minimal) : VLIWPacketizerList(MF, MLI, AA), MBPI(MBPI), MLI(&MLI), Minimal(Minimal) { HII = MF.getSubtarget().getInstrInfo(); HRI = MF.getSubtarget().getRegisterInfo(); addMutation(llvm::make_unique()); addMutation(llvm::make_unique()); addMutation(llvm::make_unique()); } // Check if FirstI modifies a register that SecondI reads. static bool hasWriteToReadDep(const MachineInstr &FirstI, const MachineInstr &SecondI, const TargetRegisterInfo *TRI) { for (auto &MO : FirstI.operands()) { if (!MO.isReg() || !MO.isDef()) continue; unsigned R = MO.getReg(); if (SecondI.readsRegister(R, TRI)) return true; } return false; } static MachineBasicBlock::iterator moveInstrOut(MachineInstr &MI, MachineBasicBlock::iterator BundleIt, bool Before) { MachineBasicBlock::instr_iterator InsertPt; if (Before) InsertPt = BundleIt.getInstrIterator(); else InsertPt = std::next(BundleIt).getInstrIterator(); MachineBasicBlock &B = *MI.getParent(); // The instruction should at least be bundled with the preceding instruction // (there will always be one, i.e. BUNDLE, if nothing else). assert(MI.isBundledWithPred()); if (MI.isBundledWithSucc()) { MI.clearFlag(MachineInstr::BundledSucc); MI.clearFlag(MachineInstr::BundledPred); } else { // If it's not bundled with the successor (i.e. it is the last one // in the bundle), then we can simply unbundle it from the predecessor, // which will take care of updating the predecessor's flag. MI.unbundleFromPred(); } B.splice(InsertPt, &B, MI.getIterator()); // Get the size of the bundle without asserting. MachineBasicBlock::const_instr_iterator I = BundleIt.getInstrIterator(); MachineBasicBlock::const_instr_iterator E = B.instr_end(); unsigned Size = 0; for (++I; I != E && I->isBundledWithPred(); ++I) ++Size; // If there are still two or more instructions, then there is nothing // else to be done. if (Size > 1) return BundleIt; // Otherwise, extract the single instruction out and delete the bundle. MachineBasicBlock::iterator NextIt = std::next(BundleIt); MachineInstr &SingleI = *BundleIt->getNextNode(); SingleI.unbundleFromPred(); assert(!SingleI.isBundledWithSucc()); BundleIt->eraseFromParent(); return NextIt; } bool HexagonPacketizer::runOnMachineFunction(MachineFunction &MF) { auto &HST = MF.getSubtarget(); HII = HST.getInstrInfo(); HRI = HST.getRegisterInfo(); auto &MLI = getAnalysis(); auto *AA = &getAnalysis().getAAResults(); auto *MBPI = &getAnalysis(); if (EnableGenAllInsnClass) HII->genAllInsnTimingClasses(MF); // Instantiate the packetizer. bool MinOnly = Minimal || DisablePacketizer || !HST.usePackets() || skipFunction(MF.getFunction()); HexagonPacketizerList Packetizer(MF, MLI, AA, MBPI, MinOnly); // DFA state table should not be empty. assert(Packetizer.getResourceTracker() && "Empty DFA table!"); // Loop over all basic blocks and remove KILL pseudo-instructions // These instructions confuse the dependence analysis. Consider: // D0 = ... (Insn 0) // R0 = KILL R0, D0 (Insn 1) // R0 = ... (Insn 2) // Here, Insn 1 will result in the dependence graph not emitting an output // dependence between Insn 0 and Insn 2. This can lead to incorrect // packetization for (MachineBasicBlock &MB : MF) { auto End = MB.end(); auto MI = MB.begin(); while (MI != End) { auto NextI = std::next(MI); if (MI->isKill()) { MB.erase(MI); End = MB.end(); } MI = NextI; } } // Loop over all of the basic blocks. for (auto &MB : MF) { auto Begin = MB.begin(), End = MB.end(); while (Begin != End) { // Find the first non-boundary starting from the end of the last // scheduling region. MachineBasicBlock::iterator RB = Begin; while (RB != End && HII->isSchedulingBoundary(*RB, &MB, MF)) ++RB; // Find the first boundary starting from the beginning of the new // region. MachineBasicBlock::iterator RE = RB; while (RE != End && !HII->isSchedulingBoundary(*RE, &MB, MF)) ++RE; // Add the scheduling boundary if it's not block end. if (RE != End) ++RE; // If RB == End, then RE == End. if (RB != End) Packetizer.PacketizeMIs(&MB, RB, RE); Begin = RE; } } Packetizer.unpacketizeSoloInstrs(MF); return true; } // Reserve resources for a constant extender. Trigger an assertion if the // reservation fails. void HexagonPacketizerList::reserveResourcesForConstExt() { if (!tryAllocateResourcesForConstExt(true)) llvm_unreachable("Resources not available"); } bool HexagonPacketizerList::canReserveResourcesForConstExt() { return tryAllocateResourcesForConstExt(false); } // Allocate resources (i.e. 4 bytes) for constant extender. If succeeded, // return true, otherwise, return false. bool HexagonPacketizerList::tryAllocateResourcesForConstExt(bool Reserve) { auto *ExtMI = MF.CreateMachineInstr(HII->get(Hexagon::A4_ext), DebugLoc()); bool Avail = ResourceTracker->canReserveResources(*ExtMI); if (Reserve && Avail) ResourceTracker->reserveResources(*ExtMI); MF.DeleteMachineInstr(ExtMI); return Avail; } bool HexagonPacketizerList::isCallDependent(const MachineInstr &MI, SDep::Kind DepType, unsigned DepReg) { // Check for LR dependence. if (DepReg == HRI->getRARegister()) return true; if (HII->isDeallocRet(MI)) if (DepReg == HRI->getFrameRegister() || DepReg == HRI->getStackRegister()) return true; // Call-like instructions can be packetized with preceding instructions // that define registers implicitly used or modified by the call. Explicit // uses are still prohibited, as in the case of indirect calls: // r0 = ... // J2_jumpr r0 if (DepType == SDep::Data) { for (const MachineOperand MO : MI.operands()) if (MO.isReg() && MO.getReg() == DepReg && !MO.isImplicit()) return true; } return false; } static bool isRegDependence(const SDep::Kind DepType) { return DepType == SDep::Data || DepType == SDep::Anti || DepType == SDep::Output; } static bool isDirectJump(const MachineInstr &MI) { return MI.getOpcode() == Hexagon::J2_jump; } static bool isSchedBarrier(const MachineInstr &MI) { switch (MI.getOpcode()) { case Hexagon::Y2_barrier: return true; } return false; } static bool isControlFlow(const MachineInstr &MI) { return MI.getDesc().isTerminator() || MI.getDesc().isCall(); } /// Returns true if the instruction modifies a callee-saved register. static bool doesModifyCalleeSavedReg(const MachineInstr &MI, const TargetRegisterInfo *TRI) { const MachineFunction &MF = *MI.getParent()->getParent(); for (auto *CSR = TRI->getCalleeSavedRegs(&MF); CSR && *CSR; ++CSR) if (MI.modifiesRegister(*CSR, TRI)) return true; return false; } // Returns true if an instruction can be promoted to .new predicate or // new-value store. bool HexagonPacketizerList::isNewifiable(const MachineInstr &MI, const TargetRegisterClass *NewRC) { // Vector stores can be predicated, and can be new-value stores, but // they cannot be predicated on a .new predicate value. if (NewRC == &Hexagon::PredRegsRegClass) { if (HII->isHVXVec(MI) && MI.mayStore()) return false; return HII->isPredicated(MI) && HII->getDotNewPredOp(MI, nullptr) > 0; } // If the class is not PredRegs, it could only apply to new-value stores. return HII->mayBeNewStore(MI); } // Promote an instructiont to its .cur form. // At this time, we have already made a call to canPromoteToDotCur and made // sure that it can *indeed* be promoted. bool HexagonPacketizerList::promoteToDotCur(MachineInstr &MI, SDep::Kind DepType, MachineBasicBlock::iterator &MII, const TargetRegisterClass* RC) { assert(DepType == SDep::Data); int CurOpcode = HII->getDotCurOp(MI); MI.setDesc(HII->get(CurOpcode)); return true; } void HexagonPacketizerList::cleanUpDotCur() { MachineInstr *MI = nullptr; for (auto BI : CurrentPacketMIs) { LLVM_DEBUG(dbgs() << "Cleanup packet has "; BI->dump();); if (HII->isDotCurInst(*BI)) { MI = BI; continue; } if (MI) { for (auto &MO : BI->operands()) if (MO.isReg() && MO.getReg() == MI->getOperand(0).getReg()) return; } } if (!MI) return; // We did not find a use of the CUR, so de-cur it. MI->setDesc(HII->get(HII->getNonDotCurOp(*MI))); LLVM_DEBUG(dbgs() << "Demoted CUR "; MI->dump();); } // Check to see if an instruction can be dot cur. bool HexagonPacketizerList::canPromoteToDotCur(const MachineInstr &MI, const SUnit *PacketSU, unsigned DepReg, MachineBasicBlock::iterator &MII, const TargetRegisterClass *RC) { if (!HII->isHVXVec(MI)) return false; if (!HII->isHVXVec(*MII)) return false; // Already a dot new instruction. if (HII->isDotCurInst(MI) && !HII->mayBeCurLoad(MI)) return false; if (!HII->mayBeCurLoad(MI)) return false; // The "cur value" cannot come from inline asm. if (PacketSU->getInstr()->isInlineAsm()) return false; // Make sure candidate instruction uses cur. LLVM_DEBUG(dbgs() << "Can we DOT Cur Vector MI\n"; MI.dump(); dbgs() << "in packet\n";); MachineInstr &MJ = *MII; LLVM_DEBUG({ dbgs() << "Checking CUR against "; MJ.dump(); }); unsigned DestReg = MI.getOperand(0).getReg(); bool FoundMatch = false; for (auto &MO : MJ.operands()) if (MO.isReg() && MO.getReg() == DestReg) FoundMatch = true; if (!FoundMatch) return false; // Check for existing uses of a vector register within the packet which // would be affected by converting a vector load into .cur formt. for (auto BI : CurrentPacketMIs) { LLVM_DEBUG(dbgs() << "packet has "; BI->dump();); if (BI->readsRegister(DepReg, MF.getSubtarget().getRegisterInfo())) return false; } LLVM_DEBUG(dbgs() << "Can Dot CUR MI\n"; MI.dump();); // We can convert the opcode into a .cur. return true; } // Promote an instruction to its .new form. At this time, we have already // made a call to canPromoteToDotNew and made sure that it can *indeed* be // promoted. bool HexagonPacketizerList::promoteToDotNew(MachineInstr &MI, SDep::Kind DepType, MachineBasicBlock::iterator &MII, const TargetRegisterClass* RC) { assert(DepType == SDep::Data); int NewOpcode; if (RC == &Hexagon::PredRegsRegClass) NewOpcode = HII->getDotNewPredOp(MI, MBPI); else NewOpcode = HII->getDotNewOp(MI); MI.setDesc(HII->get(NewOpcode)); return true; } bool HexagonPacketizerList::demoteToDotOld(MachineInstr &MI) { int NewOpcode = HII->getDotOldOp(MI); MI.setDesc(HII->get(NewOpcode)); return true; } bool HexagonPacketizerList::useCallersSP(MachineInstr &MI) { unsigned Opc = MI.getOpcode(); switch (Opc) { case Hexagon::S2_storerd_io: case Hexagon::S2_storeri_io: case Hexagon::S2_storerh_io: case Hexagon::S2_storerb_io: break; default: llvm_unreachable("Unexpected instruction"); } unsigned FrameSize = MF.getFrameInfo().getStackSize(); MachineOperand &Off = MI.getOperand(1); int64_t NewOff = Off.getImm() - (FrameSize + HEXAGON_LRFP_SIZE); if (HII->isValidOffset(Opc, NewOff, HRI)) { Off.setImm(NewOff); return true; } return false; } void HexagonPacketizerList::useCalleesSP(MachineInstr &MI) { unsigned Opc = MI.getOpcode(); switch (Opc) { case Hexagon::S2_storerd_io: case Hexagon::S2_storeri_io: case Hexagon::S2_storerh_io: case Hexagon::S2_storerb_io: break; default: llvm_unreachable("Unexpected instruction"); } unsigned FrameSize = MF.getFrameInfo().getStackSize(); MachineOperand &Off = MI.getOperand(1); Off.setImm(Off.getImm() + FrameSize + HEXAGON_LRFP_SIZE); } /// Return true if we can update the offset in MI so that MI and MJ /// can be packetized together. bool HexagonPacketizerList::updateOffset(SUnit *SUI, SUnit *SUJ) { assert(SUI->getInstr() && SUJ->getInstr()); MachineInstr &MI = *SUI->getInstr(); MachineInstr &MJ = *SUJ->getInstr(); unsigned BPI, OPI; if (!HII->getBaseAndOffsetPosition(MI, BPI, OPI)) return false; unsigned BPJ, OPJ; if (!HII->getBaseAndOffsetPosition(MJ, BPJ, OPJ)) return false; unsigned Reg = MI.getOperand(BPI).getReg(); if (Reg != MJ.getOperand(BPJ).getReg()) return false; // Make sure that the dependences do not restrict adding MI to the packet. // That is, ignore anti dependences, and make sure the only data dependence // involves the specific register. for (const auto &PI : SUI->Preds) if (PI.getKind() != SDep::Anti && (PI.getKind() != SDep::Data || PI.getReg() != Reg)) return false; int Incr; if (!HII->getIncrementValue(MJ, Incr)) return false; int64_t Offset = MI.getOperand(OPI).getImm(); if (!HII->isValidOffset(MI.getOpcode(), Offset+Incr, HRI)) return false; MI.getOperand(OPI).setImm(Offset + Incr); ChangedOffset = Offset; return true; } /// Undo the changed offset. This is needed if the instruction cannot be /// added to the current packet due to a different instruction. void HexagonPacketizerList::undoChangedOffset(MachineInstr &MI) { unsigned BP, OP; if (!HII->getBaseAndOffsetPosition(MI, BP, OP)) llvm_unreachable("Unable to find base and offset operands."); MI.getOperand(OP).setImm(ChangedOffset); } enum PredicateKind { PK_False, PK_True, PK_Unknown }; /// Returns true if an instruction is predicated on p0 and false if it's /// predicated on !p0. static PredicateKind getPredicateSense(const MachineInstr &MI, const HexagonInstrInfo *HII) { if (!HII->isPredicated(MI)) return PK_Unknown; if (HII->isPredicatedTrue(MI)) return PK_True; return PK_False; } static const MachineOperand &getPostIncrementOperand(const MachineInstr &MI, const HexagonInstrInfo *HII) { assert(HII->isPostIncrement(MI) && "Not a post increment operation."); #ifndef NDEBUG // Post Increment means duplicates. Use dense map to find duplicates in the // list. Caution: Densemap initializes with the minimum of 64 buckets, // whereas there are at most 5 operands in the post increment. DenseSet DefRegsSet; for (auto &MO : MI.operands()) if (MO.isReg() && MO.isDef()) DefRegsSet.insert(MO.getReg()); for (auto &MO : MI.operands()) if (MO.isReg() && MO.isUse() && DefRegsSet.count(MO.getReg())) return MO; #else if (MI.mayLoad()) { const MachineOperand &Op1 = MI.getOperand(1); // The 2nd operand is always the post increment operand in load. assert(Op1.isReg() && "Post increment operand has be to a register."); return Op1; } if (MI.getDesc().mayStore()) { const MachineOperand &Op0 = MI.getOperand(0); // The 1st operand is always the post increment operand in store. assert(Op0.isReg() && "Post increment operand has be to a register."); return Op0; } #endif // we should never come here. llvm_unreachable("mayLoad or mayStore not set for Post Increment operation"); } // Get the value being stored. static const MachineOperand& getStoreValueOperand(const MachineInstr &MI) { // value being stored is always the last operand. return MI.getOperand(MI.getNumOperands()-1); } static bool isLoadAbsSet(const MachineInstr &MI) { unsigned Opc = MI.getOpcode(); switch (Opc) { case Hexagon::L4_loadrd_ap: case Hexagon::L4_loadrb_ap: case Hexagon::L4_loadrh_ap: case Hexagon::L4_loadrub_ap: case Hexagon::L4_loadruh_ap: case Hexagon::L4_loadri_ap: return true; } return false; } static const MachineOperand &getAbsSetOperand(const MachineInstr &MI) { assert(isLoadAbsSet(MI)); return MI.getOperand(1); } // Can be new value store? // Following restrictions are to be respected in convert a store into // a new value store. // 1. If an instruction uses auto-increment, its address register cannot // be a new-value register. Arch Spec 5.4.2.1 // 2. If an instruction uses absolute-set addressing mode, its address // register cannot be a new-value register. Arch Spec 5.4.2.1. // 3. If an instruction produces a 64-bit result, its registers cannot be used // as new-value registers. Arch Spec 5.4.2.2. // 4. If the instruction that sets the new-value register is conditional, then // the instruction that uses the new-value register must also be conditional, // and both must always have their predicates evaluate identically. // Arch Spec 5.4.2.3. // 5. There is an implied restriction that a packet cannot have another store, // if there is a new value store in the packet. Corollary: if there is // already a store in a packet, there can not be a new value store. // Arch Spec: 3.4.4.2 bool HexagonPacketizerList::canPromoteToNewValueStore(const MachineInstr &MI, const MachineInstr &PacketMI, unsigned DepReg) { // Make sure we are looking at the store, that can be promoted. if (!HII->mayBeNewStore(MI)) return false; // Make sure there is dependency and can be new value'd. const MachineOperand &Val = getStoreValueOperand(MI); if (Val.isReg() && Val.getReg() != DepReg) return false; const MCInstrDesc& MCID = PacketMI.getDesc(); // First operand is always the result. const TargetRegisterClass *PacketRC = HII->getRegClass(MCID, 0, HRI, MF); // Double regs can not feed into new value store: PRM section: 5.4.2.2. if (PacketRC == &Hexagon::DoubleRegsRegClass) return false; // New-value stores are of class NV (slot 0), dual stores require class ST // in slot 0 (PRM 5.5). for (auto I : CurrentPacketMIs) { SUnit *PacketSU = MIToSUnit.find(I)->second; if (PacketSU->getInstr()->mayStore()) return false; } // Make sure it's NOT the post increment register that we are going to // new value. if (HII->isPostIncrement(MI) && getPostIncrementOperand(MI, HII).getReg() == DepReg) { return false; } if (HII->isPostIncrement(PacketMI) && PacketMI.mayLoad() && getPostIncrementOperand(PacketMI, HII).getReg() == DepReg) { // If source is post_inc, or absolute-set addressing, it can not feed // into new value store // r3 = memw(r2++#4) // memw(r30 + #-1404) = r2.new -> can not be new value store // arch spec section: 5.4.2.1. return false; } if (isLoadAbsSet(PacketMI) && getAbsSetOperand(PacketMI).getReg() == DepReg) return false; // If the source that feeds the store is predicated, new value store must // also be predicated. if (HII->isPredicated(PacketMI)) { if (!HII->isPredicated(MI)) return false; // Check to make sure that they both will have their predicates // evaluate identically. unsigned predRegNumSrc = 0; unsigned predRegNumDst = 0; const TargetRegisterClass* predRegClass = nullptr; // Get predicate register used in the source instruction. for (auto &MO : PacketMI.operands()) { if (!MO.isReg()) continue; predRegNumSrc = MO.getReg(); predRegClass = HRI->getMinimalPhysRegClass(predRegNumSrc); if (predRegClass == &Hexagon::PredRegsRegClass) break; } assert((predRegClass == &Hexagon::PredRegsRegClass) && "predicate register not found in a predicated PacketMI instruction"); // Get predicate register used in new-value store instruction. for (auto &MO : MI.operands()) { if (!MO.isReg()) continue; predRegNumDst = MO.getReg(); predRegClass = HRI->getMinimalPhysRegClass(predRegNumDst); if (predRegClass == &Hexagon::PredRegsRegClass) break; } assert((predRegClass == &Hexagon::PredRegsRegClass) && "predicate register not found in a predicated MI instruction"); // New-value register producer and user (store) need to satisfy these // constraints: // 1) Both instructions should be predicated on the same register. // 2) If producer of the new-value register is .new predicated then store // should also be .new predicated and if producer is not .new predicated // then store should not be .new predicated. // 3) Both new-value register producer and user should have same predicate // sense, i.e, either both should be negated or both should be non-negated. if (predRegNumDst != predRegNumSrc || HII->isDotNewInst(PacketMI) != HII->isDotNewInst(MI) || getPredicateSense(MI, HII) != getPredicateSense(PacketMI, HII)) return false; } // Make sure that other than the new-value register no other store instruction // register has been modified in the same packet. Predicate registers can be // modified by they should not be modified between the producer and the store // instruction as it will make them both conditional on different values. // We already know this to be true for all the instructions before and // including PacketMI. Howerver, we need to perform the check for the // remaining instructions in the packet. unsigned StartCheck = 0; for (auto I : CurrentPacketMIs) { SUnit *TempSU = MIToSUnit.find(I)->second; MachineInstr &TempMI = *TempSU->getInstr(); // Following condition is true for all the instructions until PacketMI is // reached (StartCheck is set to 0 before the for loop). // StartCheck flag is 1 for all the instructions after PacketMI. if (&TempMI != &PacketMI && !StartCheck) // Start processing only after continue; // encountering PacketMI. StartCheck = 1; if (&TempMI == &PacketMI) // We don't want to check PacketMI for dependence. continue; for (auto &MO : MI.operands()) if (MO.isReg() && TempSU->getInstr()->modifiesRegister(MO.getReg(), HRI)) return false; } // Make sure that for non-POST_INC stores: // 1. The only use of reg is DepReg and no other registers. // This handles base+index registers. // The following store can not be dot new. // Eg. r0 = add(r0, #3) // memw(r1+r0<<#2) = r0 if (!HII->isPostIncrement(MI)) { for (unsigned opNum = 0; opNum < MI.getNumOperands()-1; opNum++) { const MachineOperand &MO = MI.getOperand(opNum); if (MO.isReg() && MO.getReg() == DepReg) return false; } } // If data definition is because of implicit definition of the register, // do not newify the store. Eg. // %r9 = ZXTH %r12, implicit %d6, implicit-def %r12 // S2_storerh_io %r8, 2, killed %r12; mem:ST2[%scevgep343] for (auto &MO : PacketMI.operands()) { if (MO.isRegMask() && MO.clobbersPhysReg(DepReg)) return false; if (!MO.isReg() || !MO.isDef() || !MO.isImplicit()) continue; unsigned R = MO.getReg(); if (R == DepReg || HRI->isSuperRegister(DepReg, R)) return false; } // Handle imp-use of super reg case. There is a target independent side // change that should prevent this situation but I am handling it for // just-in-case. For example, we cannot newify R2 in the following case: // %r3 = A2_tfrsi 0; // S2_storeri_io killed %r0, 0, killed %r2, implicit killed %d1; for (auto &MO : MI.operands()) { if (MO.isReg() && MO.isUse() && MO.isImplicit() && MO.getReg() == DepReg) return false; } // Can be dot new store. return true; } // Can this MI to promoted to either new value store or new value jump. bool HexagonPacketizerList::canPromoteToNewValue(const MachineInstr &MI, const SUnit *PacketSU, unsigned DepReg, MachineBasicBlock::iterator &MII) { if (!HII->mayBeNewStore(MI)) return false; // Check to see the store can be new value'ed. MachineInstr &PacketMI = *PacketSU->getInstr(); if (canPromoteToNewValueStore(MI, PacketMI, DepReg)) return true; // Check to see the compare/jump can be new value'ed. // This is done as a pass on its own. Don't need to check it here. return false; } static bool isImplicitDependency(const MachineInstr &I, bool CheckDef, unsigned DepReg) { for (auto &MO : I.operands()) { if (CheckDef && MO.isRegMask() && MO.clobbersPhysReg(DepReg)) return true; if (!MO.isReg() || MO.getReg() != DepReg || !MO.isImplicit()) continue; if (CheckDef == MO.isDef()) return true; } return false; } // Check to see if an instruction can be dot new. bool HexagonPacketizerList::canPromoteToDotNew(const MachineInstr &MI, const SUnit *PacketSU, unsigned DepReg, MachineBasicBlock::iterator &MII, const TargetRegisterClass* RC) { // Already a dot new instruction. if (HII->isDotNewInst(MI) && !HII->mayBeNewStore(MI)) return false; if (!isNewifiable(MI, RC)) return false; const MachineInstr &PI = *PacketSU->getInstr(); // The "new value" cannot come from inline asm. if (PI.isInlineAsm()) return false; // IMPLICIT_DEFs won't materialize as real instructions, so .new makes no // sense. if (PI.isImplicitDef()) return false; // If dependency is trough an implicitly defined register, we should not // newify the use. if (isImplicitDependency(PI, true, DepReg) || isImplicitDependency(MI, false, DepReg)) return false; const MCInstrDesc& MCID = PI.getDesc(); const TargetRegisterClass *VecRC = HII->getRegClass(MCID, 0, HRI, MF); if (DisableVecDblNVStores && VecRC == &Hexagon::HvxWRRegClass) return false; // predicate .new if (RC == &Hexagon::PredRegsRegClass) return HII->predCanBeUsedAsDotNew(PI, DepReg); if (RC != &Hexagon::PredRegsRegClass && !HII->mayBeNewStore(MI)) return false; // Create a dot new machine instruction to see if resources can be // allocated. If not, bail out now. int NewOpcode = HII->getDotNewOp(MI); const MCInstrDesc &D = HII->get(NewOpcode); MachineInstr *NewMI = MF.CreateMachineInstr(D, DebugLoc()); bool ResourcesAvailable = ResourceTracker->canReserveResources(*NewMI); MF.DeleteMachineInstr(NewMI); if (!ResourcesAvailable) return false; // New Value Store only. New Value Jump generated as a separate pass. if (!canPromoteToNewValue(MI, PacketSU, DepReg, MII)) return false; return true; } // Go through the packet instructions and search for an anti dependency between // them and DepReg from MI. Consider this case: // Trying to add // a) %r1 = TFRI_cdNotPt %p3, 2 // to this packet: // { // b) %p0 = C2_or killed %p3, killed %p0 // c) %p3 = C2_tfrrp %r23 // d) %r1 = C2_cmovenewit %p3, 4 // } // The P3 from a) and d) will be complements after // a)'s P3 is converted to .new form // Anti-dep between c) and b) is irrelevant for this case bool HexagonPacketizerList::restrictingDepExistInPacket(MachineInstr &MI, unsigned DepReg) { SUnit *PacketSUDep = MIToSUnit.find(&MI)->second; for (auto I : CurrentPacketMIs) { // We only care for dependencies to predicated instructions if (!HII->isPredicated(*I)) continue; // Scheduling Unit for current insn in the packet SUnit *PacketSU = MIToSUnit.find(I)->second; // Look at dependencies between current members of the packet and // predicate defining instruction MI. Make sure that dependency is // on the exact register we care about. if (PacketSU->isSucc(PacketSUDep)) { for (unsigned i = 0; i < PacketSU->Succs.size(); ++i) { auto &Dep = PacketSU->Succs[i]; if (Dep.getSUnit() == PacketSUDep && Dep.getKind() == SDep::Anti && Dep.getReg() == DepReg) return true; } } } return false; } /// Gets the predicate register of a predicated instruction. static unsigned getPredicatedRegister(MachineInstr &MI, const HexagonInstrInfo *QII) { /// We use the following rule: The first predicate register that is a use is /// the predicate register of a predicated instruction. assert(QII->isPredicated(MI) && "Must be predicated instruction"); for (auto &Op : MI.operands()) { if (Op.isReg() && Op.getReg() && Op.isUse() && Hexagon::PredRegsRegClass.contains(Op.getReg())) return Op.getReg(); } llvm_unreachable("Unknown instruction operand layout"); return 0; } // Given two predicated instructions, this function detects whether // the predicates are complements. bool HexagonPacketizerList::arePredicatesComplements(MachineInstr &MI1, MachineInstr &MI2) { // If we don't know the predicate sense of the instructions bail out early, we // need it later. if (getPredicateSense(MI1, HII) == PK_Unknown || getPredicateSense(MI2, HII) == PK_Unknown) return false; // Scheduling unit for candidate. SUnit *SU = MIToSUnit[&MI1]; // One corner case deals with the following scenario: // Trying to add // a) %r24 = A2_tfrt %p0, %r25 // to this packet: // { // b) %r25 = A2_tfrf %p0, %r24 // c) %p0 = C2_cmpeqi %r26, 1 // } // // On general check a) and b) are complements, but presence of c) will // convert a) to .new form, and then it is not a complement. // We attempt to detect it by analyzing existing dependencies in the packet. // Analyze relationships between all existing members of the packet. // Look for Anti dependecy on the same predicate reg as used in the // candidate. for (auto I : CurrentPacketMIs) { // Scheduling Unit for current insn in the packet. SUnit *PacketSU = MIToSUnit.find(I)->second; // If this instruction in the packet is succeeded by the candidate... if (PacketSU->isSucc(SU)) { for (unsigned i = 0; i < PacketSU->Succs.size(); ++i) { auto Dep = PacketSU->Succs[i]; // The corner case exist when there is true data dependency between // candidate and one of current packet members, this dep is on // predicate reg, and there already exist anti dep on the same pred in // the packet. if (Dep.getSUnit() == SU && Dep.getKind() == SDep::Data && Hexagon::PredRegsRegClass.contains(Dep.getReg())) { // Here I know that I is predicate setting instruction with true // data dep to candidate on the register we care about - c) in the // above example. Now I need to see if there is an anti dependency // from c) to any other instruction in the same packet on the pred // reg of interest. if (restrictingDepExistInPacket(*I, Dep.getReg())) return false; } } } } // If the above case does not apply, check regular complement condition. // Check that the predicate register is the same and that the predicate // sense is different We also need to differentiate .old vs. .new: !p0 // is not complementary to p0.new. unsigned PReg1 = getPredicatedRegister(MI1, HII); unsigned PReg2 = getPredicatedRegister(MI2, HII); return PReg1 == PReg2 && Hexagon::PredRegsRegClass.contains(PReg1) && Hexagon::PredRegsRegClass.contains(PReg2) && getPredicateSense(MI1, HII) != getPredicateSense(MI2, HII) && HII->isDotNewInst(MI1) == HII->isDotNewInst(MI2); } // Initialize packetizer flags. void HexagonPacketizerList::initPacketizerState() { Dependence = false; PromotedToDotNew = false; GlueToNewValueJump = false; GlueAllocframeStore = false; FoundSequentialDependence = false; ChangedOffset = INT64_MAX; } // Ignore bundling of pseudo instructions. bool HexagonPacketizerList::ignorePseudoInstruction(const MachineInstr &MI, const MachineBasicBlock *) { if (MI.isDebugInstr()) return true; if (MI.isCFIInstruction()) return false; // We must print out inline assembly. if (MI.isInlineAsm()) return false; if (MI.isImplicitDef()) return false; // We check if MI has any functional units mapped to it. If it doesn't, // we ignore the instruction. const MCInstrDesc& TID = MI.getDesc(); auto *IS = ResourceTracker->getInstrItins()->beginStage(TID.getSchedClass()); unsigned FuncUnits = IS->getUnits(); return !FuncUnits; } bool HexagonPacketizerList::isSoloInstruction(const MachineInstr &MI) { // Ensure any bundles created by gather packetize remain seperate. if (MI.isBundle()) return true; if (MI.isEHLabel() || MI.isCFIInstruction()) return true; // Consider inline asm to not be a solo instruction by default. // Inline asm will be put in a packet temporarily, but then it will be // removed, and placed outside of the packet (before or after, depending // on dependencies). This is to reduce the impact of inline asm as a // "packet splitting" instruction. if (MI.isInlineAsm() && !ScheduleInlineAsm) return true; if (isSchedBarrier(MI)) return true; if (HII->isSolo(MI)) return true; if (MI.getOpcode() == Hexagon::A2_nop) return true; return false; } // Quick check if instructions MI and MJ cannot coexist in the same packet. // Limit the tests to be "one-way", e.g. "if MI->isBranch and MJ->isInlineAsm", // but not the symmetric case: "if MJ->isBranch and MI->isInlineAsm". // For full test call this function twice: // cannotCoexistAsymm(MI, MJ) || cannotCoexistAsymm(MJ, MI) // Doing the test only one way saves the amount of code in this function, // since every test would need to be repeated with the MI and MJ reversed. static bool cannotCoexistAsymm(const MachineInstr &MI, const MachineInstr &MJ, const HexagonInstrInfo &HII) { const MachineFunction *MF = MI.getParent()->getParent(); if (MF->getSubtarget().hasV60OpsOnly() && HII.isHVXMemWithAIndirect(MI, MJ)) return true; // An inline asm cannot be together with a branch, because we may not be // able to remove the asm out after packetizing (i.e. if the asm must be // moved past the bundle). Similarly, two asms cannot be together to avoid // complications when determining their relative order outside of a bundle. if (MI.isInlineAsm()) return MJ.isInlineAsm() || MJ.isBranch() || MJ.isBarrier() || MJ.isCall() || MJ.isTerminator(); // New-value stores cannot coexist with any other stores. if (HII.isNewValueStore(MI) && MJ.mayStore()) return true; switch (MI.getOpcode()) { case Hexagon::S2_storew_locked: case Hexagon::S4_stored_locked: case Hexagon::L2_loadw_locked: case Hexagon::L4_loadd_locked: case Hexagon::Y2_dccleana: case Hexagon::Y2_dccleaninva: case Hexagon::Y2_dcinva: case Hexagon::Y2_dczeroa: case Hexagon::Y4_l2fetch: case Hexagon::Y5_l2fetch: { // These instructions can only be grouped with ALU32 or non-floating-point // XTYPE instructions. Since there is no convenient way of identifying fp // XTYPE instructions, only allow grouping with ALU32 for now. unsigned TJ = HII.getType(MJ); if (TJ != HexagonII::TypeALU32_2op && TJ != HexagonII::TypeALU32_3op && TJ != HexagonII::TypeALU32_ADDI) return true; break; } default: break; } // "False" really means that the quick check failed to determine if // I and J cannot coexist. return false; } // Full, symmetric check. bool HexagonPacketizerList::cannotCoexist(const MachineInstr &MI, const MachineInstr &MJ) { return cannotCoexistAsymm(MI, MJ, *HII) || cannotCoexistAsymm(MJ, MI, *HII); } void HexagonPacketizerList::unpacketizeSoloInstrs(MachineFunction &MF) { for (auto &B : MF) { MachineBasicBlock::iterator BundleIt; MachineBasicBlock::instr_iterator NextI; for (auto I = B.instr_begin(), E = B.instr_end(); I != E; I = NextI) { NextI = std::next(I); MachineInstr &MI = *I; if (MI.isBundle()) BundleIt = I; if (!MI.isInsideBundle()) continue; // Decide on where to insert the instruction that we are pulling out. // Debug instructions always go before the bundle, but the placement of // INLINE_ASM depends on potential dependencies. By default, try to // put it before the bundle, but if the asm writes to a register that // other instructions in the bundle read, then we need to place it // after the bundle (to preserve the bundle semantics). bool InsertBeforeBundle; if (MI.isInlineAsm()) InsertBeforeBundle = !hasWriteToReadDep(MI, *BundleIt, HRI); else if (MI.isDebugValue()) InsertBeforeBundle = true; else continue; BundleIt = moveInstrOut(MI, BundleIt, InsertBeforeBundle); } } } // Check if a given instruction is of class "system". static bool isSystemInstr(const MachineInstr &MI) { unsigned Opc = MI.getOpcode(); switch (Opc) { case Hexagon::Y2_barrier: case Hexagon::Y2_dcfetchbo: case Hexagon::Y4_l2fetch: case Hexagon::Y5_l2fetch: return true; } return false; } bool HexagonPacketizerList::hasDeadDependence(const MachineInstr &I, const MachineInstr &J) { // The dependence graph may not include edges between dead definitions, // so without extra checks, we could end up packetizing two instruction // defining the same (dead) register. if (I.isCall() || J.isCall()) return false; if (HII->isPredicated(I) || HII->isPredicated(J)) return false; BitVector DeadDefs(Hexagon::NUM_TARGET_REGS); for (auto &MO : I.operands()) { if (!MO.isReg() || !MO.isDef() || !MO.isDead()) continue; DeadDefs[MO.getReg()] = true; } for (auto &MO : J.operands()) { if (!MO.isReg() || !MO.isDef() || !MO.isDead()) continue; unsigned R = MO.getReg(); if (R != Hexagon::USR_OVF && DeadDefs[R]) return true; } return false; } bool HexagonPacketizerList::hasControlDependence(const MachineInstr &I, const MachineInstr &J) { // A save callee-save register function call can only be in a packet // with instructions that don't write to the callee-save registers. if ((HII->isSaveCalleeSavedRegsCall(I) && doesModifyCalleeSavedReg(J, HRI)) || (HII->isSaveCalleeSavedRegsCall(J) && doesModifyCalleeSavedReg(I, HRI))) return true; // Two control flow instructions cannot go in the same packet. if (isControlFlow(I) && isControlFlow(J)) return true; // \ref-manual (7.3.4) A loop setup packet in loopN or spNloop0 cannot // contain a speculative indirect jump, // a new-value compare jump or a dealloc_return. auto isBadForLoopN = [this] (const MachineInstr &MI) -> bool { if (MI.isCall() || HII->isDeallocRet(MI) || HII->isNewValueJump(MI)) return true; if (HII->isPredicated(MI) && HII->isPredicatedNew(MI) && HII->isJumpR(MI)) return true; return false; }; if (HII->isLoopN(I) && isBadForLoopN(J)) return true; if (HII->isLoopN(J) && isBadForLoopN(I)) return true; // dealloc_return cannot appear in the same packet as a conditional or // unconditional jump. return HII->isDeallocRet(I) && (J.isBranch() || J.isCall() || J.isBarrier()); } bool HexagonPacketizerList::hasRegMaskDependence(const MachineInstr &I, const MachineInstr &J) { // Adding I to a packet that has J. // Regmasks are not reflected in the scheduling dependency graph, so // we need to check them manually. This code assumes that regmasks only // occur on calls, and the problematic case is when we add an instruction // defining a register R to a packet that has a call that clobbers R via // a regmask. Those cannot be packetized together, because the call will // be executed last. That's also a reson why it is ok to add a call // clobbering R to a packet that defines R. // Look for regmasks in J. for (const MachineOperand &OpJ : J.operands()) { if (!OpJ.isRegMask()) continue; assert((J.isCall() || HII->isTailCall(J)) && "Regmask on a non-call"); for (const MachineOperand &OpI : I.operands()) { if (OpI.isReg()) { if (OpJ.clobbersPhysReg(OpI.getReg())) return true; } else if (OpI.isRegMask()) { // Both are regmasks. Assume that they intersect. return true; } } } return false; } bool HexagonPacketizerList::hasDualStoreDependence(const MachineInstr &I, const MachineInstr &J) { bool SysI = isSystemInstr(I), SysJ = isSystemInstr(J); bool StoreI = I.mayStore(), StoreJ = J.mayStore(); if ((SysI && StoreJ) || (SysJ && StoreI)) return true; if (StoreI && StoreJ) { if (HII->isNewValueInst(J) || HII->isMemOp(J) || HII->isMemOp(I)) return true; } else { // A memop cannot be in the same packet with another memop or a store. // Two stores can be together, but here I and J cannot both be stores. bool MopStI = HII->isMemOp(I) || StoreI; bool MopStJ = HII->isMemOp(J) || StoreJ; if (MopStI && MopStJ) return true; } return (StoreJ && HII->isDeallocRet(I)) || (StoreI && HII->isDeallocRet(J)); } // SUI is the current instruction that is out side of the current packet. // SUJ is the current instruction inside the current packet against which that // SUI will be packetized. bool HexagonPacketizerList::isLegalToPacketizeTogether(SUnit *SUI, SUnit *SUJ) { assert(SUI->getInstr() && SUJ->getInstr()); MachineInstr &I = *SUI->getInstr(); MachineInstr &J = *SUJ->getInstr(); // Clear IgnoreDepMIs when Packet starts. if (CurrentPacketMIs.size() == 1) IgnoreDepMIs.clear(); MachineBasicBlock::iterator II = I.getIterator(); // Solo instructions cannot go in the packet. assert(!isSoloInstruction(I) && "Unexpected solo instr!"); if (cannotCoexist(I, J)) return false; Dependence = hasDeadDependence(I, J) || hasControlDependence(I, J); if (Dependence) return false; // Regmasks are not accounted for in the scheduling graph, so we need // to explicitly check for dependencies caused by them. They should only // appear on calls, so it's not too pessimistic to reject all regmask // dependencies. Dependence = hasRegMaskDependence(I, J); if (Dependence) return false; // Dual-store does not allow second store, if the first store is not // in SLOT0. New value store, new value jump, dealloc_return and memop // always take SLOT0. Arch spec 3.4.4.2. Dependence = hasDualStoreDependence(I, J); if (Dependence) return false; // If an instruction feeds new value jump, glue it. MachineBasicBlock::iterator NextMII = I.getIterator(); ++NextMII; if (NextMII != I.getParent()->end() && HII->isNewValueJump(*NextMII)) { MachineInstr &NextMI = *NextMII; bool secondRegMatch = false; const MachineOperand &NOp0 = NextMI.getOperand(0); const MachineOperand &NOp1 = NextMI.getOperand(1); if (NOp1.isReg() && I.getOperand(0).getReg() == NOp1.getReg()) secondRegMatch = true; for (MachineInstr *PI : CurrentPacketMIs) { // NVJ can not be part of the dual jump - Arch Spec: section 7.8. if (PI->isCall()) { Dependence = true; break; } // Validate: // 1. Packet does not have a store in it. // 2. If the first operand of the nvj is newified, and the second // operand is also a reg, it (second reg) is not defined in // the same packet. // 3. If the second operand of the nvj is newified, (which means // first operand is also a reg), first reg is not defined in // the same packet. if (PI->getOpcode() == Hexagon::S2_allocframe || PI->mayStore() || HII->isLoopN(*PI)) { Dependence = true; break; } // Check #2/#3. const MachineOperand &OpR = secondRegMatch ? NOp0 : NOp1; if (OpR.isReg() && PI->modifiesRegister(OpR.getReg(), HRI)) { Dependence = true; break; } } GlueToNewValueJump = true; if (Dependence) return false; } // There no dependency between a prolog instruction and its successor. if (!SUJ->isSucc(SUI)) return true; for (unsigned i = 0; i < SUJ->Succs.size(); ++i) { if (FoundSequentialDependence) break; if (SUJ->Succs[i].getSUnit() != SUI) continue; SDep::Kind DepType = SUJ->Succs[i].getKind(); // For direct calls: // Ignore register dependences for call instructions for packetization // purposes except for those due to r31 and predicate registers. // // For indirect calls: // Same as direct calls + check for true dependences to the register // used in the indirect call. // // We completely ignore Order dependences for call instructions. // // For returns: // Ignore register dependences for return instructions like jumpr, // dealloc return unless we have dependencies on the explicit uses // of the registers used by jumpr (like r31) or dealloc return // (like r29 or r30). unsigned DepReg = 0; const TargetRegisterClass *RC = nullptr; if (DepType == SDep::Data) { DepReg = SUJ->Succs[i].getReg(); RC = HRI->getMinimalPhysRegClass(DepReg); } if (I.isCall() || HII->isJumpR(I) || I.isReturn() || HII->isTailCall(I)) { if (!isRegDependence(DepType)) continue; if (!isCallDependent(I, DepType, SUJ->Succs[i].getReg())) continue; } if (DepType == SDep::Data) { if (canPromoteToDotCur(J, SUJ, DepReg, II, RC)) if (promoteToDotCur(J, DepType, II, RC)) continue; } // Data dpendence ok if we have load.cur. if (DepType == SDep::Data && HII->isDotCurInst(J)) { if (HII->isHVXVec(I)) continue; } // For instructions that can be promoted to dot-new, try to promote. if (DepType == SDep::Data) { if (canPromoteToDotNew(I, SUJ, DepReg, II, RC)) { if (promoteToDotNew(I, DepType, II, RC)) { PromotedToDotNew = true; if (cannotCoexist(I, J)) FoundSequentialDependence = true; continue; } } if (HII->isNewValueJump(I)) continue; } // For predicated instructions, if the predicates are complements then // there can be no dependence. if (HII->isPredicated(I) && HII->isPredicated(J) && arePredicatesComplements(I, J)) { // Not always safe to do this translation. // DAG Builder attempts to reduce dependence edges using transitive // nature of dependencies. Here is an example: // // r0 = tfr_pt ... (1) // r0 = tfr_pf ... (2) // r0 = tfr_pt ... (3) // // There will be an output dependence between (1)->(2) and (2)->(3). // However, there is no dependence edge between (1)->(3). This results // in all 3 instructions going in the same packet. We ignore dependce // only once to avoid this situation. auto Itr = find(IgnoreDepMIs, &J); if (Itr != IgnoreDepMIs.end()) { Dependence = true; return false; } IgnoreDepMIs.push_back(&I); continue; } // Ignore Order dependences between unconditional direct branches // and non-control-flow instructions. if (isDirectJump(I) && !J.isBranch() && !J.isCall() && DepType == SDep::Order) continue; // Ignore all dependences for jumps except for true and output // dependences. if (I.isConditionalBranch() && DepType != SDep::Data && DepType != SDep::Output) continue; if (DepType == SDep::Output) { FoundSequentialDependence = true; break; } // For Order dependences: // 1. Volatile loads/stores can be packetized together, unless other // rules prevent is. // 2. Store followed by a load is not allowed. // 3. Store followed by a store is valid. // 4. Load followed by any memory operation is allowed. if (DepType == SDep::Order) { if (!PacketizeVolatiles) { bool OrdRefs = I.hasOrderedMemoryRef() || J.hasOrderedMemoryRef(); if (OrdRefs) { FoundSequentialDependence = true; break; } } // J is first, I is second. bool LoadJ = J.mayLoad(), StoreJ = J.mayStore(); bool LoadI = I.mayLoad(), StoreI = I.mayStore(); bool NVStoreJ = HII->isNewValueStore(J); bool NVStoreI = HII->isNewValueStore(I); bool IsVecJ = HII->isHVXVec(J); bool IsVecI = HII->isHVXVec(I); if (Slot1Store && MF.getSubtarget().hasV65Ops() && ((LoadJ && StoreI && !NVStoreI) || (StoreJ && LoadI && !NVStoreJ)) && (J.getOpcode() != Hexagon::S2_allocframe && I.getOpcode() != Hexagon::S2_allocframe) && (J.getOpcode() != Hexagon::L2_deallocframe && I.getOpcode() != Hexagon::L2_deallocframe) && (!HII->isMemOp(J) && !HII->isMemOp(I)) && (!IsVecJ && !IsVecI)) setmemShufDisabled(true); else if (StoreJ && LoadI && alias(J, I)) { FoundSequentialDependence = true; break; } if (!StoreJ) if (!LoadJ || (!LoadI && !StoreI)) { // If J is neither load nor store, assume a dependency. // If J is a load, but I is neither, also assume a dependency. FoundSequentialDependence = true; break; } // Store followed by store: not OK on V2. // Store followed by load: not OK on all. // Load followed by store: OK on all. // Load followed by load: OK on all. continue; } // Special case for ALLOCFRAME: even though there is dependency // between ALLOCFRAME and subsequent store, allow it to be packetized // in a same packet. This implies that the store is using the caller's // SP. Hence, offset needs to be updated accordingly. if (DepType == SDep::Data && J.getOpcode() == Hexagon::S2_allocframe) { unsigned Opc = I.getOpcode(); switch (Opc) { case Hexagon::S2_storerd_io: case Hexagon::S2_storeri_io: case Hexagon::S2_storerh_io: case Hexagon::S2_storerb_io: if (I.getOperand(0).getReg() == HRI->getStackRegister()) { // Since this store is to be glued with allocframe in the same // packet, it will use SP of the previous stack frame, i.e. // caller's SP. Therefore, we need to recalculate offset // according to this change. GlueAllocframeStore = useCallersSP(I); if (GlueAllocframeStore) continue; } break; default: break; } } // There are certain anti-dependencies that cannot be ignored. // Specifically: // J2_call ... implicit-def %r0 ; SUJ // R0 = ... ; SUI // Those cannot be packetized together, since the call will observe // the effect of the assignment to R0. if ((DepType == SDep::Anti || DepType == SDep::Output) && J.isCall()) { // Check if I defines any volatile register. We should also check // registers that the call may read, but these happen to be a // subset of the volatile register set. for (const MachineOperand &Op : I.operands()) { if (Op.isReg() && Op.isDef()) { unsigned R = Op.getReg(); if (!J.readsRegister(R, HRI) && !J.modifiesRegister(R, HRI)) continue; } else if (!Op.isRegMask()) { // If I has a regmask assume dependency. continue; } FoundSequentialDependence = true; break; } } // Skip over remaining anti-dependences. Two instructions that are // anti-dependent can share a packet, since in most such cases all // operands are read before any modifications take place. // The exceptions are branch and call instructions, since they are // executed after all other instructions have completed (at least // conceptually). if (DepType != SDep::Anti) { FoundSequentialDependence = true; break; } } if (FoundSequentialDependence) { Dependence = true; return false; } return true; } bool HexagonPacketizerList::isLegalToPruneDependencies(SUnit *SUI, SUnit *SUJ) { assert(SUI->getInstr() && SUJ->getInstr()); MachineInstr &I = *SUI->getInstr(); MachineInstr &J = *SUJ->getInstr(); bool Coexist = !cannotCoexist(I, J); if (Coexist && !Dependence) return true; // Check if the instruction was promoted to a dot-new. If so, demote it // back into a dot-old. if (PromotedToDotNew) demoteToDotOld(I); cleanUpDotCur(); // Check if the instruction (must be a store) was glued with an allocframe // instruction. If so, restore its offset to its original value, i.e. use // current SP instead of caller's SP. if (GlueAllocframeStore) { useCalleesSP(I); GlueAllocframeStore = false; } if (ChangedOffset != INT64_MAX) undoChangedOffset(I); if (GlueToNewValueJump) { // Putting I and J together would prevent the new-value jump from being // packetized with the producer. In that case I and J must be separated. GlueToNewValueJump = false; return false; } if (!Coexist) return false; if (ChangedOffset == INT64_MAX && updateOffset(SUI, SUJ)) { FoundSequentialDependence = false; Dependence = false; return true; } return false; } bool HexagonPacketizerList::foundLSInPacket() { bool FoundLoad = false; bool FoundStore = false; for (auto MJ : CurrentPacketMIs) { unsigned Opc = MJ->getOpcode(); if (Opc == Hexagon::S2_allocframe || Opc == Hexagon::L2_deallocframe) continue; if (HII->isMemOp(*MJ)) continue; if (MJ->mayLoad()) FoundLoad = true; if (MJ->mayStore() && !HII->isNewValueStore(*MJ)) FoundStore = true; } return FoundLoad && FoundStore; } MachineBasicBlock::iterator HexagonPacketizerList::addToPacket(MachineInstr &MI) { MachineBasicBlock::iterator MII = MI.getIterator(); MachineBasicBlock *MBB = MI.getParent(); if (CurrentPacketMIs.empty()) PacketStalls = false; PacketStalls |= producesStall(MI); if (MI.isImplicitDef()) { // Add to the packet to allow subsequent instructions to be checked // properly. CurrentPacketMIs.push_back(&MI); return MII; } assert(ResourceTracker->canReserveResources(MI)); bool ExtMI = HII->isExtended(MI) || HII->isConstExtended(MI); bool Good = true; if (GlueToNewValueJump) { MachineInstr &NvjMI = *++MII; // We need to put both instructions in the same packet: MI and NvjMI. // Either of them can require a constant extender. Try to add both to // the current packet, and if that fails, end the packet and start a // new one. ResourceTracker->reserveResources(MI); if (ExtMI) Good = tryAllocateResourcesForConstExt(true); bool ExtNvjMI = HII->isExtended(NvjMI) || HII->isConstExtended(NvjMI); if (Good) { if (ResourceTracker->canReserveResources(NvjMI)) ResourceTracker->reserveResources(NvjMI); else Good = false; } if (Good && ExtNvjMI) Good = tryAllocateResourcesForConstExt(true); if (!Good) { endPacket(MBB, MI); assert(ResourceTracker->canReserveResources(MI)); ResourceTracker->reserveResources(MI); if (ExtMI) { assert(canReserveResourcesForConstExt()); tryAllocateResourcesForConstExt(true); } assert(ResourceTracker->canReserveResources(NvjMI)); ResourceTracker->reserveResources(NvjMI); if (ExtNvjMI) { assert(canReserveResourcesForConstExt()); reserveResourcesForConstExt(); } } CurrentPacketMIs.push_back(&MI); CurrentPacketMIs.push_back(&NvjMI); return MII; } ResourceTracker->reserveResources(MI); if (ExtMI && !tryAllocateResourcesForConstExt(true)) { endPacket(MBB, MI); if (PromotedToDotNew) demoteToDotOld(MI); if (GlueAllocframeStore) { useCalleesSP(MI); GlueAllocframeStore = false; } ResourceTracker->reserveResources(MI); reserveResourcesForConstExt(); } CurrentPacketMIs.push_back(&MI); return MII; } void HexagonPacketizerList::endPacket(MachineBasicBlock *MBB, MachineBasicBlock::iterator EndMI) { // Replace VLIWPacketizerList::endPacket(MBB, EndMI). bool memShufDisabled = getmemShufDisabled(); if (memShufDisabled && !foundLSInPacket()) { setmemShufDisabled(false); LLVM_DEBUG(dbgs() << " Not added to NoShufPacket\n"); } memShufDisabled = getmemShufDisabled(); OldPacketMIs.clear(); for (MachineInstr *MI : CurrentPacketMIs) { MachineBasicBlock::instr_iterator NextMI = std::next(MI->getIterator()); for (auto &I : make_range(HII->expandVGatherPseudo(*MI), NextMI)) OldPacketMIs.push_back(&I); } CurrentPacketMIs.clear(); if (OldPacketMIs.size() > 1) { MachineBasicBlock::instr_iterator FirstMI(OldPacketMIs.front()); MachineBasicBlock::instr_iterator LastMI(EndMI.getInstrIterator()); finalizeBundle(*MBB, FirstMI, LastMI); auto BundleMII = std::prev(FirstMI); if (memShufDisabled) HII->setBundleNoShuf(BundleMII); setmemShufDisabled(false); } ResourceTracker->clearResources(); LLVM_DEBUG(dbgs() << "End packet\n"); } bool HexagonPacketizerList::shouldAddToPacket(const MachineInstr &MI) { if (Minimal) return false; return !producesStall(MI); } // V60 forward scheduling. bool HexagonPacketizerList::producesStall(const MachineInstr &I) { // If the packet already stalls, then ignore the stall from a subsequent // instruction in the same packet. if (PacketStalls) return false; // Check whether the previous packet is in a different loop. If this is the // case, there is little point in trying to avoid a stall because that would // favor the rare case (loop entry) over the common case (loop iteration). // // TODO: We should really be able to check all the incoming edges if this is // the first packet in a basic block, so we can avoid stalls from the loop // backedge. if (!OldPacketMIs.empty()) { auto *OldBB = OldPacketMIs.front()->getParent(); auto *ThisBB = I.getParent(); if (MLI->getLoopFor(OldBB) != MLI->getLoopFor(ThisBB)) return false; } SUnit *SUI = MIToSUnit[const_cast(&I)]; // If the latency is 0 and there is a data dependence between this // instruction and any instruction in the current packet, we disregard any // potential stalls due to the instructions in the previous packet. Most of // the instruction pairs that can go together in the same packet have 0 // latency between them. The exceptions are // 1. NewValueJumps as they're generated much later and the latencies can't // be changed at that point. // 2. .cur instructions, if its consumer has a 0 latency successor (such as // .new). In this case, the latency between .cur and the consumer stays // non-zero even though we can have both .cur and .new in the same packet. // Changing the latency to 0 is not an option as it causes software pipeliner // to not pipeline in some cases. // For Example: // { // I1: v6.cur = vmem(r0++#1) // I2: v7 = valign(v6,v4,r2) // I3: vmem(r5++#1) = v7.new // } // Here I2 and I3 has 0 cycle latency, but I1 and I2 has 2. for (auto J : CurrentPacketMIs) { SUnit *SUJ = MIToSUnit[J]; for (auto &Pred : SUI->Preds) if (Pred.getSUnit() == SUJ) if ((Pred.getLatency() == 0 && Pred.isAssignedRegDep()) || HII->isNewValueJump(I) || HII->isToBeScheduledASAP(*J, I)) return false; } // Check if the latency is greater than one between this instruction and any // instruction in the previous packet. for (auto J : OldPacketMIs) { SUnit *SUJ = MIToSUnit[J]; for (auto &Pred : SUI->Preds) if (Pred.getSUnit() == SUJ && Pred.getLatency() > 1) return true; } return false; } //===----------------------------------------------------------------------===// // Public Constructor Functions //===----------------------------------------------------------------------===// FunctionPass *llvm::createHexagonPacketizer(bool Minimal) { return new HexagonPacketizer(Minimal); }