//==--- InstrEmitter.cpp - Emit MachineInstrs for the SelectionDAG class ---==// // // 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 the Emit routines for the SelectionDAG class, which creates // MachineInstrs based on the decisions of the SelectionDAG instruction // selection. // //===----------------------------------------------------------------------===// #include "InstrEmitter.h" #include "SDNodeDbgValue.h" #include "llvm/ADT/Statistic.h" #include "llvm/CodeGen/MachineConstantPool.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineInstrBuilder.h" #include "llvm/CodeGen/MachineRegisterInfo.h" #include "llvm/CodeGen/SelectionDAG.h" #include "llvm/CodeGen/StackMaps.h" #include "llvm/CodeGen/TargetInstrInfo.h" #include "llvm/CodeGen/TargetLowering.h" #include "llvm/CodeGen/TargetSubtargetInfo.h" #include "llvm/IR/DataLayout.h" #include "llvm/IR/DebugInfo.h" #include "llvm/IR/PseudoProbe.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/MathExtras.h" #include "llvm/Target/TargetMachine.h" using namespace llvm; #define DEBUG_TYPE "instr-emitter" /// MinRCSize - Smallest register class we allow when constraining virtual /// registers. If satisfying all register class constraints would require /// using a smaller register class, emit a COPY to a new virtual register /// instead. const unsigned MinRCSize = 4; /// CountResults - The results of target nodes have register or immediate /// operands first, then an optional chain, and optional glue operands (which do /// not go into the resulting MachineInstr). unsigned InstrEmitter::CountResults(SDNode *Node) { unsigned N = Node->getNumValues(); while (N && Node->getValueType(N - 1) == MVT::Glue) --N; if (N && Node->getValueType(N - 1) == MVT::Other) --N; // Skip over chain result. return N; } /// countOperands - The inputs to target nodes have any actual inputs first, /// followed by an optional chain operand, then an optional glue operand. /// Compute the number of actual operands that will go into the resulting /// MachineInstr. /// /// Also count physreg RegisterSDNode and RegisterMaskSDNode operands preceding /// the chain and glue. These operands may be implicit on the machine instr. static unsigned countOperands(SDNode *Node, unsigned NumExpUses, unsigned &NumImpUses) { unsigned N = Node->getNumOperands(); while (N && Node->getOperand(N - 1).getValueType() == MVT::Glue) --N; if (N && Node->getOperand(N - 1).getValueType() == MVT::Other) --N; // Ignore chain if it exists. // Count RegisterSDNode and RegisterMaskSDNode operands for NumImpUses. NumImpUses = N - NumExpUses; for (unsigned I = N; I > NumExpUses; --I) { if (isa(Node->getOperand(I - 1))) continue; if (RegisterSDNode *RN = dyn_cast(Node->getOperand(I - 1))) if (Register::isPhysicalRegister(RN->getReg())) continue; NumImpUses = N - I; break; } return N; } /// EmitCopyFromReg - Generate machine code for an CopyFromReg node or an /// implicit physical register output. void InstrEmitter:: EmitCopyFromReg(SDNode *Node, unsigned ResNo, bool IsClone, bool IsCloned, Register SrcReg, DenseMap &VRBaseMap) { Register VRBase; if (SrcReg.isVirtual()) { // Just use the input register directly! SDValue Op(Node, ResNo); if (IsClone) VRBaseMap.erase(Op); bool isNew = VRBaseMap.insert(std::make_pair(Op, SrcReg)).second; (void)isNew; // Silence compiler warning. assert(isNew && "Node emitted out of order - early"); return; } // If the node is only used by a CopyToReg and the dest reg is a vreg, use // the CopyToReg'd destination register instead of creating a new vreg. bool MatchReg = true; const TargetRegisterClass *UseRC = nullptr; MVT VT = Node->getSimpleValueType(ResNo); // Stick to the preferred register classes for legal types. if (TLI->isTypeLegal(VT)) UseRC = TLI->getRegClassFor(VT, Node->isDivergent()); if (!IsClone && !IsCloned) for (SDNode *User : Node->uses()) { bool Match = true; if (User->getOpcode() == ISD::CopyToReg && User->getOperand(2).getNode() == Node && User->getOperand(2).getResNo() == ResNo) { Register DestReg = cast(User->getOperand(1))->getReg(); if (DestReg.isVirtual()) { VRBase = DestReg; Match = false; } else if (DestReg != SrcReg) Match = false; } else { for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i) { SDValue Op = User->getOperand(i); if (Op.getNode() != Node || Op.getResNo() != ResNo) continue; MVT VT = Node->getSimpleValueType(Op.getResNo()); if (VT == MVT::Other || VT == MVT::Glue) continue; Match = false; if (User->isMachineOpcode()) { const MCInstrDesc &II = TII->get(User->getMachineOpcode()); const TargetRegisterClass *RC = nullptr; if (i+II.getNumDefs() < II.getNumOperands()) { RC = TRI->getAllocatableClass( TII->getRegClass(II, i+II.getNumDefs(), TRI, *MF)); } if (!UseRC) UseRC = RC; else if (RC) { const TargetRegisterClass *ComRC = TRI->getCommonSubClass(UseRC, RC); // If multiple uses expect disjoint register classes, we emit // copies in AddRegisterOperand. if (ComRC) UseRC = ComRC; } } } } MatchReg &= Match; if (VRBase) break; } const TargetRegisterClass *SrcRC = nullptr, *DstRC = nullptr; SrcRC = TRI->getMinimalPhysRegClass(SrcReg, VT); // Figure out the register class to create for the destreg. if (VRBase) { DstRC = MRI->getRegClass(VRBase); } else if (UseRC) { assert(TRI->isTypeLegalForClass(*UseRC, VT) && "Incompatible phys register def and uses!"); DstRC = UseRC; } else { DstRC = TLI->getRegClassFor(VT, Node->isDivergent()); } // If all uses are reading from the src physical register and copying the // register is either impossible or very expensive, then don't create a copy. if (MatchReg && SrcRC->getCopyCost() < 0) { VRBase = SrcReg; } else { // Create the reg, emit the copy. VRBase = MRI->createVirtualRegister(DstRC); BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(TargetOpcode::COPY), VRBase).addReg(SrcReg); } SDValue Op(Node, ResNo); if (IsClone) VRBaseMap.erase(Op); bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second; (void)isNew; // Silence compiler warning. assert(isNew && "Node emitted out of order - early"); } void InstrEmitter::CreateVirtualRegisters(SDNode *Node, MachineInstrBuilder &MIB, const MCInstrDesc &II, bool IsClone, bool IsCloned, DenseMap &VRBaseMap) { assert(Node->getMachineOpcode() != TargetOpcode::IMPLICIT_DEF && "IMPLICIT_DEF should have been handled as a special case elsewhere!"); unsigned NumResults = CountResults(Node); bool HasVRegVariadicDefs = !MF->getTarget().usesPhysRegsForValues() && II.isVariadic() && II.variadicOpsAreDefs(); unsigned NumVRegs = HasVRegVariadicDefs ? NumResults : II.getNumDefs(); if (Node->getMachineOpcode() == TargetOpcode::STATEPOINT) NumVRegs = NumResults; for (unsigned i = 0; i < NumVRegs; ++i) { // If the specific node value is only used by a CopyToReg and the dest reg // is a vreg in the same register class, use the CopyToReg'd destination // register instead of creating a new vreg. Register VRBase; const TargetRegisterClass *RC = TRI->getAllocatableClass(TII->getRegClass(II, i, TRI, *MF)); // Always let the value type influence the used register class. The // constraints on the instruction may be too lax to represent the value // type correctly. For example, a 64-bit float (X86::FR64) can't live in // the 32-bit float super-class (X86::FR32). if (i < NumResults && TLI->isTypeLegal(Node->getSimpleValueType(i))) { const TargetRegisterClass *VTRC = TLI->getRegClassFor( Node->getSimpleValueType(i), (Node->isDivergent() || (RC && TRI->isDivergentRegClass(RC)))); if (RC) VTRC = TRI->getCommonSubClass(RC, VTRC); if (VTRC) RC = VTRC; } if (II.OpInfo != nullptr && II.OpInfo[i].isOptionalDef()) { // Optional def must be a physical register. VRBase = cast(Node->getOperand(i-NumResults))->getReg(); assert(VRBase.isPhysical()); MIB.addReg(VRBase, RegState::Define); } if (!VRBase && !IsClone && !IsCloned) for (SDNode *User : Node->uses()) { if (User->getOpcode() == ISD::CopyToReg && User->getOperand(2).getNode() == Node && User->getOperand(2).getResNo() == i) { unsigned Reg = cast(User->getOperand(1))->getReg(); if (Register::isVirtualRegister(Reg)) { const TargetRegisterClass *RegRC = MRI->getRegClass(Reg); if (RegRC == RC) { VRBase = Reg; MIB.addReg(VRBase, RegState::Define); break; } } } } // Create the result registers for this node and add the result regs to // the machine instruction. if (VRBase == 0) { assert(RC && "Isn't a register operand!"); VRBase = MRI->createVirtualRegister(RC); MIB.addReg(VRBase, RegState::Define); } // If this def corresponds to a result of the SDNode insert the VRBase into // the lookup map. if (i < NumResults) { SDValue Op(Node, i); if (IsClone) VRBaseMap.erase(Op); bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second; (void)isNew; // Silence compiler warning. assert(isNew && "Node emitted out of order - early"); } } } /// getVR - Return the virtual register corresponding to the specified result /// of the specified node. Register InstrEmitter::getVR(SDValue Op, DenseMap &VRBaseMap) { if (Op.isMachineOpcode() && Op.getMachineOpcode() == TargetOpcode::IMPLICIT_DEF) { // Add an IMPLICIT_DEF instruction before every use. // IMPLICIT_DEF can produce any type of result so its MCInstrDesc // does not include operand register class info. const TargetRegisterClass *RC = TLI->getRegClassFor( Op.getSimpleValueType(), Op.getNode()->isDivergent()); Register VReg = MRI->createVirtualRegister(RC); BuildMI(*MBB, InsertPos, Op.getDebugLoc(), TII->get(TargetOpcode::IMPLICIT_DEF), VReg); return VReg; } DenseMap::iterator I = VRBaseMap.find(Op); assert(I != VRBaseMap.end() && "Node emitted out of order - late"); return I->second; } /// AddRegisterOperand - Add the specified register as an operand to the /// specified machine instr. Insert register copies if the register is /// not in the required register class. void InstrEmitter::AddRegisterOperand(MachineInstrBuilder &MIB, SDValue Op, unsigned IIOpNum, const MCInstrDesc *II, DenseMap &VRBaseMap, bool IsDebug, bool IsClone, bool IsCloned) { assert(Op.getValueType() != MVT::Other && Op.getValueType() != MVT::Glue && "Chain and glue operands should occur at end of operand list!"); // Get/emit the operand. Register VReg = getVR(Op, VRBaseMap); const MCInstrDesc &MCID = MIB->getDesc(); bool isOptDef = IIOpNum < MCID.getNumOperands() && MCID.OpInfo[IIOpNum].isOptionalDef(); // If the instruction requires a register in a different class, create // a new virtual register and copy the value into it, but first attempt to // shrink VReg's register class within reason. For example, if VReg == GR32 // and II requires a GR32_NOSP, just constrain VReg to GR32_NOSP. if (II) { const TargetRegisterClass *OpRC = nullptr; if (IIOpNum < II->getNumOperands()) OpRC = TII->getRegClass(*II, IIOpNum, TRI, *MF); if (OpRC) { const TargetRegisterClass *ConstrainedRC = MRI->constrainRegClass(VReg, OpRC, MinRCSize); if (!ConstrainedRC) { OpRC = TRI->getAllocatableClass(OpRC); assert(OpRC && "Constraints cannot be fulfilled for allocation"); Register NewVReg = MRI->createVirtualRegister(OpRC); BuildMI(*MBB, InsertPos, Op.getNode()->getDebugLoc(), TII->get(TargetOpcode::COPY), NewVReg).addReg(VReg); VReg = NewVReg; } else { assert(ConstrainedRC->isAllocatable() && "Constraining an allocatable VReg produced an unallocatable class?"); } } } // If this value has only one use, that use is a kill. This is a // conservative approximation. InstrEmitter does trivial coalescing // with CopyFromReg nodes, so don't emit kill flags for them. // Avoid kill flags on Schedule cloned nodes, since there will be // multiple uses. // Tied operands are never killed, so we need to check that. And that // means we need to determine the index of the operand. bool isKill = Op.hasOneUse() && Op.getNode()->getOpcode() != ISD::CopyFromReg && !IsDebug && !(IsClone || IsCloned); if (isKill) { unsigned Idx = MIB->getNumOperands(); while (Idx > 0 && MIB->getOperand(Idx-1).isReg() && MIB->getOperand(Idx-1).isImplicit()) --Idx; bool isTied = MCID.getOperandConstraint(Idx, MCOI::TIED_TO) != -1; if (isTied) isKill = false; } MIB.addReg(VReg, getDefRegState(isOptDef) | getKillRegState(isKill) | getDebugRegState(IsDebug)); } /// AddOperand - Add the specified operand to the specified machine instr. II /// specifies the instruction information for the node, and IIOpNum is the /// operand number (in the II) that we are adding. void InstrEmitter::AddOperand(MachineInstrBuilder &MIB, SDValue Op, unsigned IIOpNum, const MCInstrDesc *II, DenseMap &VRBaseMap, bool IsDebug, bool IsClone, bool IsCloned) { if (Op.isMachineOpcode()) { AddRegisterOperand(MIB, Op, IIOpNum, II, VRBaseMap, IsDebug, IsClone, IsCloned); } else if (ConstantSDNode *C = dyn_cast(Op)) { MIB.addImm(C->getSExtValue()); } else if (ConstantFPSDNode *F = dyn_cast(Op)) { MIB.addFPImm(F->getConstantFPValue()); } else if (RegisterSDNode *R = dyn_cast(Op)) { Register VReg = R->getReg(); MVT OpVT = Op.getSimpleValueType(); const TargetRegisterClass *IIRC = II ? TRI->getAllocatableClass(TII->getRegClass(*II, IIOpNum, TRI, *MF)) : nullptr; const TargetRegisterClass *OpRC = TLI->isTypeLegal(OpVT) ? TLI->getRegClassFor(OpVT, Op.getNode()->isDivergent() || (IIRC && TRI->isDivergentRegClass(IIRC))) : nullptr; if (OpRC && IIRC && OpRC != IIRC && Register::isVirtualRegister(VReg)) { Register NewVReg = MRI->createVirtualRegister(IIRC); BuildMI(*MBB, InsertPos, Op.getNode()->getDebugLoc(), TII->get(TargetOpcode::COPY), NewVReg).addReg(VReg); VReg = NewVReg; } // Turn additional physreg operands into implicit uses on non-variadic // instructions. This is used by call and return instructions passing // arguments in registers. bool Imp = II && (IIOpNum >= II->getNumOperands() && !II->isVariadic()); MIB.addReg(VReg, getImplRegState(Imp)); } else if (RegisterMaskSDNode *RM = dyn_cast(Op)) { MIB.addRegMask(RM->getRegMask()); } else if (GlobalAddressSDNode *TGA = dyn_cast(Op)) { MIB.addGlobalAddress(TGA->getGlobal(), TGA->getOffset(), TGA->getTargetFlags()); } else if (BasicBlockSDNode *BBNode = dyn_cast(Op)) { MIB.addMBB(BBNode->getBasicBlock()); } else if (FrameIndexSDNode *FI = dyn_cast(Op)) { MIB.addFrameIndex(FI->getIndex()); } else if (JumpTableSDNode *JT = dyn_cast(Op)) { MIB.addJumpTableIndex(JT->getIndex(), JT->getTargetFlags()); } else if (ConstantPoolSDNode *CP = dyn_cast(Op)) { int Offset = CP->getOffset(); Align Alignment = CP->getAlign(); unsigned Idx; MachineConstantPool *MCP = MF->getConstantPool(); if (CP->isMachineConstantPoolEntry()) Idx = MCP->getConstantPoolIndex(CP->getMachineCPVal(), Alignment); else Idx = MCP->getConstantPoolIndex(CP->getConstVal(), Alignment); MIB.addConstantPoolIndex(Idx, Offset, CP->getTargetFlags()); } else if (ExternalSymbolSDNode *ES = dyn_cast(Op)) { MIB.addExternalSymbol(ES->getSymbol(), ES->getTargetFlags()); } else if (auto *SymNode = dyn_cast(Op)) { MIB.addSym(SymNode->getMCSymbol()); } else if (BlockAddressSDNode *BA = dyn_cast(Op)) { MIB.addBlockAddress(BA->getBlockAddress(), BA->getOffset(), BA->getTargetFlags()); } else if (TargetIndexSDNode *TI = dyn_cast(Op)) { MIB.addTargetIndex(TI->getIndex(), TI->getOffset(), TI->getTargetFlags()); } else { assert(Op.getValueType() != MVT::Other && Op.getValueType() != MVT::Glue && "Chain and glue operands should occur at end of operand list!"); AddRegisterOperand(MIB, Op, IIOpNum, II, VRBaseMap, IsDebug, IsClone, IsCloned); } } Register InstrEmitter::ConstrainForSubReg(Register VReg, unsigned SubIdx, MVT VT, bool isDivergent, const DebugLoc &DL) { const TargetRegisterClass *VRC = MRI->getRegClass(VReg); const TargetRegisterClass *RC = TRI->getSubClassWithSubReg(VRC, SubIdx); // RC is a sub-class of VRC that supports SubIdx. Try to constrain VReg // within reason. if (RC && RC != VRC) RC = MRI->constrainRegClass(VReg, RC, MinRCSize); // VReg has been adjusted. It can be used with SubIdx operands now. if (RC) return VReg; // VReg couldn't be reasonably constrained. Emit a COPY to a new virtual // register instead. RC = TRI->getSubClassWithSubReg(TLI->getRegClassFor(VT, isDivergent), SubIdx); assert(RC && "No legal register class for VT supports that SubIdx"); Register NewReg = MRI->createVirtualRegister(RC); BuildMI(*MBB, InsertPos, DL, TII->get(TargetOpcode::COPY), NewReg) .addReg(VReg); return NewReg; } /// EmitSubregNode - Generate machine code for subreg nodes. /// void InstrEmitter::EmitSubregNode(SDNode *Node, DenseMap &VRBaseMap, bool IsClone, bool IsCloned) { Register VRBase; unsigned Opc = Node->getMachineOpcode(); // If the node is only used by a CopyToReg and the dest reg is a vreg, use // the CopyToReg'd destination register instead of creating a new vreg. for (SDNode *User : Node->uses()) { if (User->getOpcode() == ISD::CopyToReg && User->getOperand(2).getNode() == Node) { Register DestReg = cast(User->getOperand(1))->getReg(); if (DestReg.isVirtual()) { VRBase = DestReg; break; } } } if (Opc == TargetOpcode::EXTRACT_SUBREG) { // EXTRACT_SUBREG is lowered as %dst = COPY %src:sub. There are no // constraints on the %dst register, COPY can target all legal register // classes. unsigned SubIdx = cast(Node->getOperand(1))->getZExtValue(); const TargetRegisterClass *TRC = TLI->getRegClassFor(Node->getSimpleValueType(0), Node->isDivergent()); Register Reg; MachineInstr *DefMI; RegisterSDNode *R = dyn_cast(Node->getOperand(0)); if (R && Register::isPhysicalRegister(R->getReg())) { Reg = R->getReg(); DefMI = nullptr; } else { Reg = R ? R->getReg() : getVR(Node->getOperand(0), VRBaseMap); DefMI = MRI->getVRegDef(Reg); } Register SrcReg, DstReg; unsigned DefSubIdx; if (DefMI && TII->isCoalescableExtInstr(*DefMI, SrcReg, DstReg, DefSubIdx) && SubIdx == DefSubIdx && TRC == MRI->getRegClass(SrcReg)) { // Optimize these: // r1025 = s/zext r1024, 4 // r1026 = extract_subreg r1025, 4 // to a copy // r1026 = copy r1024 VRBase = MRI->createVirtualRegister(TRC); BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(TargetOpcode::COPY), VRBase).addReg(SrcReg); MRI->clearKillFlags(SrcReg); } else { // Reg may not support a SubIdx sub-register, and we may need to // constrain its register class or issue a COPY to a compatible register // class. if (Reg.isVirtual()) Reg = ConstrainForSubReg(Reg, SubIdx, Node->getOperand(0).getSimpleValueType(), Node->isDivergent(), Node->getDebugLoc()); // Create the destreg if it is missing. if (!VRBase) VRBase = MRI->createVirtualRegister(TRC); // Create the extract_subreg machine instruction. MachineInstrBuilder CopyMI = BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(TargetOpcode::COPY), VRBase); if (Reg.isVirtual()) CopyMI.addReg(Reg, 0, SubIdx); else CopyMI.addReg(TRI->getSubReg(Reg, SubIdx)); } } else if (Opc == TargetOpcode::INSERT_SUBREG || Opc == TargetOpcode::SUBREG_TO_REG) { SDValue N0 = Node->getOperand(0); SDValue N1 = Node->getOperand(1); SDValue N2 = Node->getOperand(2); unsigned SubIdx = cast(N2)->getZExtValue(); // Figure out the register class to create for the destreg. It should be // the largest legal register class supporting SubIdx sub-registers. // RegisterCoalescer will constrain it further if it decides to eliminate // the INSERT_SUBREG instruction. // // %dst = INSERT_SUBREG %src, %sub, SubIdx // // is lowered by TwoAddressInstructionPass to: // // %dst = COPY %src // %dst:SubIdx = COPY %sub // // There is no constraint on the %src register class. // const TargetRegisterClass *SRC = TLI->getRegClassFor(Node->getSimpleValueType(0), Node->isDivergent()); SRC = TRI->getSubClassWithSubReg(SRC, SubIdx); assert(SRC && "No register class supports VT and SubIdx for INSERT_SUBREG"); if (VRBase == 0 || !SRC->hasSubClassEq(MRI->getRegClass(VRBase))) VRBase = MRI->createVirtualRegister(SRC); // Create the insert_subreg or subreg_to_reg machine instruction. MachineInstrBuilder MIB = BuildMI(*MF, Node->getDebugLoc(), TII->get(Opc), VRBase); // If creating a subreg_to_reg, then the first input operand // is an implicit value immediate, otherwise it's a register if (Opc == TargetOpcode::SUBREG_TO_REG) { const ConstantSDNode *SD = cast(N0); MIB.addImm(SD->getZExtValue()); } else AddOperand(MIB, N0, 0, nullptr, VRBaseMap, /*IsDebug=*/false, IsClone, IsCloned); // Add the subregister being inserted AddOperand(MIB, N1, 0, nullptr, VRBaseMap, /*IsDebug=*/false, IsClone, IsCloned); MIB.addImm(SubIdx); MBB->insert(InsertPos, MIB); } else llvm_unreachable("Node is not insert_subreg, extract_subreg, or subreg_to_reg"); SDValue Op(Node, 0); bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second; (void)isNew; // Silence compiler warning. assert(isNew && "Node emitted out of order - early"); } /// EmitCopyToRegClassNode - Generate machine code for COPY_TO_REGCLASS nodes. /// COPY_TO_REGCLASS is just a normal copy, except that the destination /// register is constrained to be in a particular register class. /// void InstrEmitter::EmitCopyToRegClassNode(SDNode *Node, DenseMap &VRBaseMap) { unsigned VReg = getVR(Node->getOperand(0), VRBaseMap); // Create the new VReg in the destination class and emit a copy. unsigned DstRCIdx = cast(Node->getOperand(1))->getZExtValue(); const TargetRegisterClass *DstRC = TRI->getAllocatableClass(TRI->getRegClass(DstRCIdx)); Register NewVReg = MRI->createVirtualRegister(DstRC); BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(TargetOpcode::COPY), NewVReg).addReg(VReg); SDValue Op(Node, 0); bool isNew = VRBaseMap.insert(std::make_pair(Op, NewVReg)).second; (void)isNew; // Silence compiler warning. assert(isNew && "Node emitted out of order - early"); } /// EmitRegSequence - Generate machine code for REG_SEQUENCE nodes. /// void InstrEmitter::EmitRegSequence(SDNode *Node, DenseMap &VRBaseMap, bool IsClone, bool IsCloned) { unsigned DstRCIdx = cast(Node->getOperand(0))->getZExtValue(); const TargetRegisterClass *RC = TRI->getRegClass(DstRCIdx); Register NewVReg = MRI->createVirtualRegister(TRI->getAllocatableClass(RC)); const MCInstrDesc &II = TII->get(TargetOpcode::REG_SEQUENCE); MachineInstrBuilder MIB = BuildMI(*MF, Node->getDebugLoc(), II, NewVReg); unsigned NumOps = Node->getNumOperands(); // If the input pattern has a chain, then the root of the corresponding // output pattern will get a chain as well. This can happen to be a // REG_SEQUENCE (which is not "guarded" by countOperands/CountResults). if (NumOps && Node->getOperand(NumOps-1).getValueType() == MVT::Other) --NumOps; // Ignore chain if it exists. assert((NumOps & 1) == 1 && "REG_SEQUENCE must have an odd number of operands!"); for (unsigned i = 1; i != NumOps; ++i) { SDValue Op = Node->getOperand(i); if ((i & 1) == 0) { RegisterSDNode *R = dyn_cast(Node->getOperand(i-1)); // Skip physical registers as they don't have a vreg to get and we'll // insert copies for them in TwoAddressInstructionPass anyway. if (!R || !Register::isPhysicalRegister(R->getReg())) { unsigned SubIdx = cast(Op)->getZExtValue(); unsigned SubReg = getVR(Node->getOperand(i-1), VRBaseMap); const TargetRegisterClass *TRC = MRI->getRegClass(SubReg); const TargetRegisterClass *SRC = TRI->getMatchingSuperRegClass(RC, TRC, SubIdx); if (SRC && SRC != RC) { MRI->setRegClass(NewVReg, SRC); RC = SRC; } } } AddOperand(MIB, Op, i+1, &II, VRBaseMap, /*IsDebug=*/false, IsClone, IsCloned); } MBB->insert(InsertPos, MIB); SDValue Op(Node, 0); bool isNew = VRBaseMap.insert(std::make_pair(Op, NewVReg)).second; (void)isNew; // Silence compiler warning. assert(isNew && "Node emitted out of order - early"); } /// EmitDbgValue - Generate machine instruction for a dbg_value node. /// MachineInstr * InstrEmitter::EmitDbgValue(SDDbgValue *SD, DenseMap &VRBaseMap) { MDNode *Var = SD->getVariable(); MDNode *Expr = SD->getExpression(); DebugLoc DL = SD->getDebugLoc(); assert(cast(Var)->isValidLocationForIntrinsic(DL) && "Expected inlined-at fields to agree"); SD->setIsEmitted(); if (SD->isInvalidated()) { // An invalidated SDNode must generate an undef DBG_VALUE: although the // original value is no longer computed, earlier DBG_VALUEs live ranges // must not leak into later code. auto MIB = BuildMI(*MF, DL, TII->get(TargetOpcode::DBG_VALUE)); MIB.addReg(0U); MIB.addReg(0U, RegState::Debug); MIB.addMetadata(Var); MIB.addMetadata(Expr); return &*MIB; } // Attempt to produce a DBG_INSTR_REF if we've been asked to. if (EmitDebugInstrRefs) if (auto *InstrRef = EmitDbgInstrRef(SD, VRBaseMap)) return InstrRef; if (SD->getKind() == SDDbgValue::FRAMEIX) { // Stack address; this needs to be lowered in target-dependent fashion. // EmitTargetCodeForFrameDebugValue is responsible for allocation. auto FrameMI = BuildMI(*MF, DL, TII->get(TargetOpcode::DBG_VALUE)) .addFrameIndex(SD->getFrameIx()); if (SD->isIndirect()) // Push [fi + 0] onto the DIExpression stack. FrameMI.addImm(0); else // Push fi onto the DIExpression stack. FrameMI.addReg(0); return FrameMI.addMetadata(Var).addMetadata(Expr); } // Otherwise, we're going to create an instruction here. const MCInstrDesc &II = TII->get(TargetOpcode::DBG_VALUE); MachineInstrBuilder MIB = BuildMI(*MF, DL, II); if (SD->getKind() == SDDbgValue::SDNODE) { SDNode *Node = SD->getSDNode(); SDValue Op = SDValue(Node, SD->getResNo()); // It's possible we replaced this SDNode with other(s) and therefore // didn't generate code for it. It's better to catch these cases where // they happen and transfer the debug info, but trying to guarantee that // in all cases would be very fragile; this is a safeguard for any // that were missed. DenseMap::iterator I = VRBaseMap.find(Op); if (I==VRBaseMap.end()) MIB.addReg(0U); // undef else AddOperand(MIB, Op, (*MIB).getNumOperands(), &II, VRBaseMap, /*IsDebug=*/true, /*IsClone=*/false, /*IsCloned=*/false); } else if (SD->getKind() == SDDbgValue::VREG) { MIB.addReg(SD->getVReg(), RegState::Debug); } else if (SD->getKind() == SDDbgValue::CONST) { const Value *V = SD->getConst(); if (const ConstantInt *CI = dyn_cast(V)) { if (CI->getBitWidth() > 64) MIB.addCImm(CI); else MIB.addImm(CI->getSExtValue()); } else if (const ConstantFP *CF = dyn_cast(V)) { MIB.addFPImm(CF); } else if (isa(V)) { // Note: This assumes that all nullptr constants are zero-valued. MIB.addImm(0); } else { // Could be an Undef. In any case insert an Undef so we can see what we // dropped. MIB.addReg(0U); } } else { // Insert an Undef so we can see what we dropped. MIB.addReg(0U); } // Indirect addressing is indicated by an Imm as the second parameter. if (SD->isIndirect()) MIB.addImm(0U); else MIB.addReg(0U, RegState::Debug); MIB.addMetadata(Var); MIB.addMetadata(Expr); return &*MIB; } MachineInstr * InstrEmitter::EmitDbgInstrRef(SDDbgValue *SD, DenseMap &VRBaseMap) { // Instruction referencing is still in a prototype state: for now we're only // going to support SDNodes within a block. Copies are not supported, they // don't actually define a value. if (SD->getKind() != SDDbgValue::SDNODE) return nullptr; SDNode *Node = SD->getSDNode(); SDValue Op = SDValue(Node, SD->getResNo()); DenseMap::iterator I = VRBaseMap.find(Op); if (I==VRBaseMap.end()) return nullptr; // undef value: let EmitDbgValue produce a DBG_VALUE $noreg. MDNode *Var = SD->getVariable(); MDNode *Expr = SD->getExpression(); DebugLoc DL = SD->getDebugLoc(); // Try to pick out a defining instruction at this point. unsigned VReg = getVR(Op, VRBaseMap); MachineInstr *ResultInstr = nullptr; // No definition corresponds to scenarios where a vreg is live-in to a block, // and doesn't have a defining instruction (yet). This can be patched up // later; at this early stage of implementation, fall back to using DBG_VALUE. if (!MRI->hasOneDef(VReg)) return nullptr; MachineInstr &DefMI = *MRI->def_instr_begin(VReg); // Some target specific opcodes can become copies. As stated above, we're // ignoring those for now. if (DefMI.isCopy() || DefMI.getOpcode() == TargetOpcode::SUBREG_TO_REG) return nullptr; const MCInstrDesc &RefII = TII->get(TargetOpcode::DBG_INSTR_REF); auto MIB = BuildMI(*MF, DL, RefII); // Find the operand which defines the specified VReg. unsigned OperandIdx = 0; for (const auto &MO : DefMI.operands()) { if (MO.isReg() && MO.isDef() && MO.getReg() == VReg) break; ++OperandIdx; } assert(OperandIdx < DefMI.getNumOperands()); // Make the DBG_INSTR_REF refer to that instruction, and that operand. unsigned InstrNum = DefMI.getDebugInstrNum(); MIB.addImm(InstrNum); MIB.addImm(OperandIdx); MIB.addMetadata(Var); MIB.addMetadata(Expr); ResultInstr = &*MIB; return ResultInstr; } MachineInstr * InstrEmitter::EmitDbgLabel(SDDbgLabel *SD) { MDNode *Label = SD->getLabel(); DebugLoc DL = SD->getDebugLoc(); assert(cast(Label)->isValidLocationForIntrinsic(DL) && "Expected inlined-at fields to agree"); const MCInstrDesc &II = TII->get(TargetOpcode::DBG_LABEL); MachineInstrBuilder MIB = BuildMI(*MF, DL, II); MIB.addMetadata(Label); return &*MIB; } /// EmitMachineNode - Generate machine code for a target-specific node and /// needed dependencies. /// void InstrEmitter:: EmitMachineNode(SDNode *Node, bool IsClone, bool IsCloned, DenseMap &VRBaseMap) { unsigned Opc = Node->getMachineOpcode(); // Handle subreg insert/extract specially if (Opc == TargetOpcode::EXTRACT_SUBREG || Opc == TargetOpcode::INSERT_SUBREG || Opc == TargetOpcode::SUBREG_TO_REG) { EmitSubregNode(Node, VRBaseMap, IsClone, IsCloned); return; } // Handle COPY_TO_REGCLASS specially. if (Opc == TargetOpcode::COPY_TO_REGCLASS) { EmitCopyToRegClassNode(Node, VRBaseMap); return; } // Handle REG_SEQUENCE specially. if (Opc == TargetOpcode::REG_SEQUENCE) { EmitRegSequence(Node, VRBaseMap, IsClone, IsCloned); return; } if (Opc == TargetOpcode::IMPLICIT_DEF) // We want a unique VR for each IMPLICIT_DEF use. return; const MCInstrDesc &II = TII->get(Opc); unsigned NumResults = CountResults(Node); unsigned NumDefs = II.getNumDefs(); const MCPhysReg *ScratchRegs = nullptr; // Handle STACKMAP and PATCHPOINT specially and then use the generic code. if (Opc == TargetOpcode::STACKMAP || Opc == TargetOpcode::PATCHPOINT) { // Stackmaps do not have arguments and do not preserve their calling // convention. However, to simplify runtime support, they clobber the same // scratch registers as AnyRegCC. unsigned CC = CallingConv::AnyReg; if (Opc == TargetOpcode::PATCHPOINT) { CC = Node->getConstantOperandVal(PatchPointOpers::CCPos); NumDefs = NumResults; } ScratchRegs = TLI->getScratchRegisters((CallingConv::ID) CC); } else if (Opc == TargetOpcode::STATEPOINT) { NumDefs = NumResults; } unsigned NumImpUses = 0; unsigned NodeOperands = countOperands(Node, II.getNumOperands() - NumDefs, NumImpUses); bool HasVRegVariadicDefs = !MF->getTarget().usesPhysRegsForValues() && II.isVariadic() && II.variadicOpsAreDefs(); bool HasPhysRegOuts = NumResults > NumDefs && II.getImplicitDefs() != nullptr && !HasVRegVariadicDefs; #ifndef NDEBUG unsigned NumMIOperands = NodeOperands + NumResults; if (II.isVariadic()) assert(NumMIOperands >= II.getNumOperands() && "Too few operands for a variadic node!"); else assert(NumMIOperands >= II.getNumOperands() && NumMIOperands <= II.getNumOperands() + II.getNumImplicitDefs() + NumImpUses && "#operands for dag node doesn't match .td file!"); #endif // Create the new machine instruction. MachineInstrBuilder MIB = BuildMI(*MF, Node->getDebugLoc(), II); // Add result register values for things that are defined by this // instruction. if (NumResults) { CreateVirtualRegisters(Node, MIB, II, IsClone, IsCloned, VRBaseMap); // Transfer any IR flags from the SDNode to the MachineInstr MachineInstr *MI = MIB.getInstr(); const SDNodeFlags Flags = Node->getFlags(); if (Flags.hasNoSignedZeros()) MI->setFlag(MachineInstr::MIFlag::FmNsz); if (Flags.hasAllowReciprocal()) MI->setFlag(MachineInstr::MIFlag::FmArcp); if (Flags.hasNoNaNs()) MI->setFlag(MachineInstr::MIFlag::FmNoNans); if (Flags.hasNoInfs()) MI->setFlag(MachineInstr::MIFlag::FmNoInfs); if (Flags.hasAllowContract()) MI->setFlag(MachineInstr::MIFlag::FmContract); if (Flags.hasApproximateFuncs()) MI->setFlag(MachineInstr::MIFlag::FmAfn); if (Flags.hasAllowReassociation()) MI->setFlag(MachineInstr::MIFlag::FmReassoc); if (Flags.hasNoUnsignedWrap()) MI->setFlag(MachineInstr::MIFlag::NoUWrap); if (Flags.hasNoSignedWrap()) MI->setFlag(MachineInstr::MIFlag::NoSWrap); if (Flags.hasExact()) MI->setFlag(MachineInstr::MIFlag::IsExact); if (Flags.hasNoFPExcept()) MI->setFlag(MachineInstr::MIFlag::NoFPExcept); } // Emit all of the actual operands of this instruction, adding them to the // instruction as appropriate. bool HasOptPRefs = NumDefs > NumResults; assert((!HasOptPRefs || !HasPhysRegOuts) && "Unable to cope with optional defs and phys regs defs!"); unsigned NumSkip = HasOptPRefs ? NumDefs - NumResults : 0; for (unsigned i = NumSkip; i != NodeOperands; ++i) AddOperand(MIB, Node->getOperand(i), i-NumSkip+NumDefs, &II, VRBaseMap, /*IsDebug=*/false, IsClone, IsCloned); // Add scratch registers as implicit def and early clobber if (ScratchRegs) for (unsigned i = 0; ScratchRegs[i]; ++i) MIB.addReg(ScratchRegs[i], RegState::ImplicitDefine | RegState::EarlyClobber); // Set the memory reference descriptions of this instruction now that it is // part of the function. MIB.setMemRefs(cast(Node)->memoperands()); // Insert the instruction into position in the block. This needs to // happen before any custom inserter hook is called so that the // hook knows where in the block to insert the replacement code. MBB->insert(InsertPos, MIB); // The MachineInstr may also define physregs instead of virtregs. These // physreg values can reach other instructions in different ways: // // 1. When there is a use of a Node value beyond the explicitly defined // virtual registers, we emit a CopyFromReg for one of the implicitly // defined physregs. This only happens when HasPhysRegOuts is true. // // 2. A CopyFromReg reading a physreg may be glued to this instruction. // // 3. A glued instruction may implicitly use a physreg. // // 4. A glued instruction may use a RegisterSDNode operand. // // Collect all the used physreg defs, and make sure that any unused physreg // defs are marked as dead. SmallVector UsedRegs; // Additional results must be physical register defs. if (HasPhysRegOuts) { for (unsigned i = NumDefs; i < NumResults; ++i) { Register Reg = II.getImplicitDefs()[i - NumDefs]; if (!Node->hasAnyUseOfValue(i)) continue; // This implicitly defined physreg has a use. UsedRegs.push_back(Reg); EmitCopyFromReg(Node, i, IsClone, IsCloned, Reg, VRBaseMap); } } // Scan the glue chain for any used physregs. if (Node->getValueType(Node->getNumValues()-1) == MVT::Glue) { for (SDNode *F = Node->getGluedUser(); F; F = F->getGluedUser()) { if (F->getOpcode() == ISD::CopyFromReg) { UsedRegs.push_back(cast(F->getOperand(1))->getReg()); continue; } else if (F->getOpcode() == ISD::CopyToReg) { // Skip CopyToReg nodes that are internal to the glue chain. continue; } // Collect declared implicit uses. const MCInstrDesc &MCID = TII->get(F->getMachineOpcode()); UsedRegs.append(MCID.getImplicitUses(), MCID.getImplicitUses() + MCID.getNumImplicitUses()); // In addition to declared implicit uses, we must also check for // direct RegisterSDNode operands. for (unsigned i = 0, e = F->getNumOperands(); i != e; ++i) if (RegisterSDNode *R = dyn_cast(F->getOperand(i))) { Register Reg = R->getReg(); if (Reg.isPhysical()) UsedRegs.push_back(Reg); } } } // Finally mark unused registers as dead. if (!UsedRegs.empty() || II.getImplicitDefs() || II.hasOptionalDef()) MIB->setPhysRegsDeadExcept(UsedRegs, *TRI); // STATEPOINT is too 'dynamic' to have meaningful machine description. // We have to manually tie operands. if (Opc == TargetOpcode::STATEPOINT && NumDefs > 0) { assert(!HasPhysRegOuts && "STATEPOINT mishandled"); MachineInstr *MI = MIB; unsigned Def = 0; int First = StatepointOpers(MI).getFirstGCPtrIdx(); assert(First > 0 && "Statepoint has Defs but no GC ptr list"); unsigned Use = (unsigned)First; while (Def < NumDefs) { if (MI->getOperand(Use).isReg()) MI->tieOperands(Def++, Use); Use = StackMaps::getNextMetaArgIdx(MI, Use); } } // Run post-isel target hook to adjust this instruction if needed. if (II.hasPostISelHook()) TLI->AdjustInstrPostInstrSelection(*MIB, Node); } /// EmitSpecialNode - Generate machine code for a target-independent node and /// needed dependencies. void InstrEmitter:: EmitSpecialNode(SDNode *Node, bool IsClone, bool IsCloned, DenseMap &VRBaseMap) { switch (Node->getOpcode()) { default: #ifndef NDEBUG Node->dump(); #endif llvm_unreachable("This target-independent node should have been selected!"); case ISD::EntryToken: llvm_unreachable("EntryToken should have been excluded from the schedule!"); case ISD::MERGE_VALUES: case ISD::TokenFactor: // fall thru break; case ISD::CopyToReg: { Register DestReg = cast(Node->getOperand(1))->getReg(); SDValue SrcVal = Node->getOperand(2); if (Register::isVirtualRegister(DestReg) && SrcVal.isMachineOpcode() && SrcVal.getMachineOpcode() == TargetOpcode::IMPLICIT_DEF) { // Instead building a COPY to that vreg destination, build an // IMPLICIT_DEF instruction instead. BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(TargetOpcode::IMPLICIT_DEF), DestReg); break; } Register SrcReg; if (RegisterSDNode *R = dyn_cast(SrcVal)) SrcReg = R->getReg(); else SrcReg = getVR(SrcVal, VRBaseMap); if (SrcReg == DestReg) // Coalesced away the copy? Ignore. break; BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(TargetOpcode::COPY), DestReg).addReg(SrcReg); break; } case ISD::CopyFromReg: { unsigned SrcReg = cast(Node->getOperand(1))->getReg(); EmitCopyFromReg(Node, 0, IsClone, IsCloned, SrcReg, VRBaseMap); break; } case ISD::EH_LABEL: case ISD::ANNOTATION_LABEL: { unsigned Opc = (Node->getOpcode() == ISD::EH_LABEL) ? TargetOpcode::EH_LABEL : TargetOpcode::ANNOTATION_LABEL; MCSymbol *S = cast(Node)->getLabel(); BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(Opc)).addSym(S); break; } case ISD::LIFETIME_START: case ISD::LIFETIME_END: { unsigned TarOp = (Node->getOpcode() == ISD::LIFETIME_START) ? TargetOpcode::LIFETIME_START : TargetOpcode::LIFETIME_END; FrameIndexSDNode *FI = dyn_cast(Node->getOperand(1)); BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(TarOp)) .addFrameIndex(FI->getIndex()); break; } case ISD::PSEUDO_PROBE: { unsigned TarOp = TargetOpcode::PSEUDO_PROBE; auto Guid = cast(Node)->getGuid(); auto Index = cast(Node)->getIndex(); auto Attr = cast(Node)->getAttributes(); BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(TarOp)) .addImm(Guid) .addImm(Index) .addImm((uint8_t)PseudoProbeType::Block) .addImm(Attr); break; } case ISD::INLINEASM: case ISD::INLINEASM_BR: { unsigned NumOps = Node->getNumOperands(); if (Node->getOperand(NumOps-1).getValueType() == MVT::Glue) --NumOps; // Ignore the glue operand. // Create the inline asm machine instruction. unsigned TgtOpc = Node->getOpcode() == ISD::INLINEASM_BR ? TargetOpcode::INLINEASM_BR : TargetOpcode::INLINEASM; MachineInstrBuilder MIB = BuildMI(*MF, Node->getDebugLoc(), TII->get(TgtOpc)); // Add the asm string as an external symbol operand. SDValue AsmStrV = Node->getOperand(InlineAsm::Op_AsmString); const char *AsmStr = cast(AsmStrV)->getSymbol(); MIB.addExternalSymbol(AsmStr); // Add the HasSideEffect, isAlignStack, AsmDialect, MayLoad and MayStore // bits. int64_t ExtraInfo = cast(Node->getOperand(InlineAsm::Op_ExtraInfo))-> getZExtValue(); MIB.addImm(ExtraInfo); // Remember to operand index of the group flags. SmallVector GroupIdx; // Remember registers that are part of early-clobber defs. SmallVector ECRegs; // Add all of the operand registers to the instruction. for (unsigned i = InlineAsm::Op_FirstOperand; i != NumOps;) { unsigned Flags = cast(Node->getOperand(i))->getZExtValue(); const unsigned NumVals = InlineAsm::getNumOperandRegisters(Flags); GroupIdx.push_back(MIB->getNumOperands()); MIB.addImm(Flags); ++i; // Skip the ID value. switch (InlineAsm::getKind(Flags)) { default: llvm_unreachable("Bad flags!"); case InlineAsm::Kind_RegDef: for (unsigned j = 0; j != NumVals; ++j, ++i) { unsigned Reg = cast(Node->getOperand(i))->getReg(); // FIXME: Add dead flags for physical and virtual registers defined. // For now, mark physical register defs as implicit to help fast // regalloc. This makes inline asm look a lot like calls. MIB.addReg(Reg, RegState::Define | getImplRegState(Register::isPhysicalRegister(Reg))); } break; case InlineAsm::Kind_RegDefEarlyClobber: case InlineAsm::Kind_Clobber: for (unsigned j = 0; j != NumVals; ++j, ++i) { unsigned Reg = cast(Node->getOperand(i))->getReg(); MIB.addReg(Reg, RegState::Define | RegState::EarlyClobber | getImplRegState(Register::isPhysicalRegister(Reg))); ECRegs.push_back(Reg); } break; case InlineAsm::Kind_RegUse: // Use of register. case InlineAsm::Kind_Imm: // Immediate. case InlineAsm::Kind_Mem: // Addressing mode. // The addressing mode has been selected, just add all of the // operands to the machine instruction. for (unsigned j = 0; j != NumVals; ++j, ++i) AddOperand(MIB, Node->getOperand(i), 0, nullptr, VRBaseMap, /*IsDebug=*/false, IsClone, IsCloned); // Manually set isTied bits. if (InlineAsm::getKind(Flags) == InlineAsm::Kind_RegUse) { unsigned DefGroup = 0; if (InlineAsm::isUseOperandTiedToDef(Flags, DefGroup)) { unsigned DefIdx = GroupIdx[DefGroup] + 1; unsigned UseIdx = GroupIdx.back() + 1; for (unsigned j = 0; j != NumVals; ++j) MIB->tieOperands(DefIdx + j, UseIdx + j); } } break; } } // GCC inline assembly allows input operands to also be early-clobber // output operands (so long as the operand is written only after it's // used), but this does not match the semantics of our early-clobber flag. // If an early-clobber operand register is also an input operand register, // then remove the early-clobber flag. for (unsigned Reg : ECRegs) { if (MIB->readsRegister(Reg, TRI)) { MachineOperand *MO = MIB->findRegisterDefOperand(Reg, false, false, TRI); assert(MO && "No def operand for clobbered register?"); MO->setIsEarlyClobber(false); } } // Get the mdnode from the asm if it exists and add it to the instruction. SDValue MDV = Node->getOperand(InlineAsm::Op_MDNode); const MDNode *MD = cast(MDV)->getMD(); if (MD) MIB.addMetadata(MD); MBB->insert(InsertPos, MIB); break; } } } /// InstrEmitter - Construct an InstrEmitter and set it to start inserting /// at the given position in the given block. InstrEmitter::InstrEmitter(const TargetMachine &TM, MachineBasicBlock *mbb, MachineBasicBlock::iterator insertpos) : MF(mbb->getParent()), MRI(&MF->getRegInfo()), TII(MF->getSubtarget().getInstrInfo()), TRI(MF->getSubtarget().getRegisterInfo()), TLI(MF->getSubtarget().getTargetLowering()), MBB(mbb), InsertPos(insertpos) { EmitDebugInstrRefs = TM.Options.ValueTrackingVariableLocations; }