|  | //===- ARMBaseInstrInfo.cpp - ARM Instruction Information -----------*- C++ -*-===// | 
|  | // | 
|  | //                     The LLVM Compiler Infrastructure | 
|  | // | 
|  | // This file is distributed under the University of Illinois Open Source | 
|  | // License. See LICENSE.TXT for details. | 
|  | // | 
|  | //===----------------------------------------------------------------------===// | 
|  | // | 
|  | // This file contains the Base ARM implementation of the TargetInstrInfo class. | 
|  | // | 
|  | //===----------------------------------------------------------------------===// | 
|  |  | 
|  | #include "ARMBaseInstrInfo.h" | 
|  | #include "ARM.h" | 
|  | #include "ARMAddressingModes.h" | 
|  | #include "ARMGenInstrInfo.inc" | 
|  | #include "ARMMachineFunctionInfo.h" | 
|  | #include "llvm/ADT/STLExtras.h" | 
|  | #include "llvm/CodeGen/LiveVariables.h" | 
|  | #include "llvm/CodeGen/MachineFrameInfo.h" | 
|  | #include "llvm/CodeGen/MachineInstrBuilder.h" | 
|  | #include "llvm/CodeGen/MachineJumpTableInfo.h" | 
|  | #include "llvm/Target/TargetAsmInfo.h" | 
|  | #include "llvm/Support/CommandLine.h" | 
|  | #include "llvm/Support/ErrorHandling.h" | 
|  | using namespace llvm; | 
|  |  | 
|  | static cl::opt<bool> | 
|  | EnableARM3Addr("enable-arm-3-addr-conv", cl::Hidden, | 
|  | cl::desc("Enable ARM 2-addr to 3-addr conv")); | 
|  |  | 
|  | ARMBaseInstrInfo::ARMBaseInstrInfo() | 
|  | : TargetInstrInfoImpl(ARMInsts, array_lengthof(ARMInsts)) { | 
|  | } | 
|  |  | 
|  | MachineInstr * | 
|  | ARMBaseInstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI, | 
|  | MachineBasicBlock::iterator &MBBI, | 
|  | LiveVariables *LV) const { | 
|  | // FIXME: Thumb2 support. | 
|  |  | 
|  | if (!EnableARM3Addr) | 
|  | return NULL; | 
|  |  | 
|  | MachineInstr *MI = MBBI; | 
|  | MachineFunction &MF = *MI->getParent()->getParent(); | 
|  | unsigned TSFlags = MI->getDesc().TSFlags; | 
|  | bool isPre = false; | 
|  | switch ((TSFlags & ARMII::IndexModeMask) >> ARMII::IndexModeShift) { | 
|  | default: return NULL; | 
|  | case ARMII::IndexModePre: | 
|  | isPre = true; | 
|  | break; | 
|  | case ARMII::IndexModePost: | 
|  | break; | 
|  | } | 
|  |  | 
|  | // Try splitting an indexed load/store to an un-indexed one plus an add/sub | 
|  | // operation. | 
|  | unsigned MemOpc = getUnindexedOpcode(MI->getOpcode()); | 
|  | if (MemOpc == 0) | 
|  | return NULL; | 
|  |  | 
|  | MachineInstr *UpdateMI = NULL; | 
|  | MachineInstr *MemMI = NULL; | 
|  | unsigned AddrMode = (TSFlags & ARMII::AddrModeMask); | 
|  | const TargetInstrDesc &TID = MI->getDesc(); | 
|  | unsigned NumOps = TID.getNumOperands(); | 
|  | bool isLoad = !TID.mayStore(); | 
|  | const MachineOperand &WB = isLoad ? MI->getOperand(1) : MI->getOperand(0); | 
|  | const MachineOperand &Base = MI->getOperand(2); | 
|  | const MachineOperand &Offset = MI->getOperand(NumOps-3); | 
|  | unsigned WBReg = WB.getReg(); | 
|  | unsigned BaseReg = Base.getReg(); | 
|  | unsigned OffReg = Offset.getReg(); | 
|  | unsigned OffImm = MI->getOperand(NumOps-2).getImm(); | 
|  | ARMCC::CondCodes Pred = (ARMCC::CondCodes)MI->getOperand(NumOps-1).getImm(); | 
|  | switch (AddrMode) { | 
|  | default: | 
|  | assert(false && "Unknown indexed op!"); | 
|  | return NULL; | 
|  | case ARMII::AddrMode2: { | 
|  | bool isSub = ARM_AM::getAM2Op(OffImm) == ARM_AM::sub; | 
|  | unsigned Amt = ARM_AM::getAM2Offset(OffImm); | 
|  | if (OffReg == 0) { | 
|  | if (ARM_AM::getSOImmVal(Amt) == -1) | 
|  | // Can't encode it in a so_imm operand. This transformation will | 
|  | // add more than 1 instruction. Abandon! | 
|  | return NULL; | 
|  | UpdateMI = BuildMI(MF, MI->getDebugLoc(), | 
|  | get(isSub ? ARM::SUBri : ARM::ADDri), WBReg) | 
|  | .addReg(BaseReg).addImm(Amt) | 
|  | .addImm(Pred).addReg(0).addReg(0); | 
|  | } else if (Amt != 0) { | 
|  | ARM_AM::ShiftOpc ShOpc = ARM_AM::getAM2ShiftOpc(OffImm); | 
|  | unsigned SOOpc = ARM_AM::getSORegOpc(ShOpc, Amt); | 
|  | UpdateMI = BuildMI(MF, MI->getDebugLoc(), | 
|  | get(isSub ? ARM::SUBrs : ARM::ADDrs), WBReg) | 
|  | .addReg(BaseReg).addReg(OffReg).addReg(0).addImm(SOOpc) | 
|  | .addImm(Pred).addReg(0).addReg(0); | 
|  | } else | 
|  | UpdateMI = BuildMI(MF, MI->getDebugLoc(), | 
|  | get(isSub ? ARM::SUBrr : ARM::ADDrr), WBReg) | 
|  | .addReg(BaseReg).addReg(OffReg) | 
|  | .addImm(Pred).addReg(0).addReg(0); | 
|  | break; | 
|  | } | 
|  | case ARMII::AddrMode3 : { | 
|  | bool isSub = ARM_AM::getAM3Op(OffImm) == ARM_AM::sub; | 
|  | unsigned Amt = ARM_AM::getAM3Offset(OffImm); | 
|  | if (OffReg == 0) | 
|  | // Immediate is 8-bits. It's guaranteed to fit in a so_imm operand. | 
|  | UpdateMI = BuildMI(MF, MI->getDebugLoc(), | 
|  | get(isSub ? ARM::SUBri : ARM::ADDri), WBReg) | 
|  | .addReg(BaseReg).addImm(Amt) | 
|  | .addImm(Pred).addReg(0).addReg(0); | 
|  | else | 
|  | UpdateMI = BuildMI(MF, MI->getDebugLoc(), | 
|  | get(isSub ? ARM::SUBrr : ARM::ADDrr), WBReg) | 
|  | .addReg(BaseReg).addReg(OffReg) | 
|  | .addImm(Pred).addReg(0).addReg(0); | 
|  | break; | 
|  | } | 
|  | } | 
|  |  | 
|  | std::vector<MachineInstr*> NewMIs; | 
|  | if (isPre) { | 
|  | if (isLoad) | 
|  | MemMI = BuildMI(MF, MI->getDebugLoc(), | 
|  | get(MemOpc), MI->getOperand(0).getReg()) | 
|  | .addReg(WBReg).addReg(0).addImm(0).addImm(Pred); | 
|  | else | 
|  | MemMI = BuildMI(MF, MI->getDebugLoc(), | 
|  | get(MemOpc)).addReg(MI->getOperand(1).getReg()) | 
|  | .addReg(WBReg).addReg(0).addImm(0).addImm(Pred); | 
|  | NewMIs.push_back(MemMI); | 
|  | NewMIs.push_back(UpdateMI); | 
|  | } else { | 
|  | if (isLoad) | 
|  | MemMI = BuildMI(MF, MI->getDebugLoc(), | 
|  | get(MemOpc), MI->getOperand(0).getReg()) | 
|  | .addReg(BaseReg).addReg(0).addImm(0).addImm(Pred); | 
|  | else | 
|  | MemMI = BuildMI(MF, MI->getDebugLoc(), | 
|  | get(MemOpc)).addReg(MI->getOperand(1).getReg()) | 
|  | .addReg(BaseReg).addReg(0).addImm(0).addImm(Pred); | 
|  | if (WB.isDead()) | 
|  | UpdateMI->getOperand(0).setIsDead(); | 
|  | NewMIs.push_back(UpdateMI); | 
|  | NewMIs.push_back(MemMI); | 
|  | } | 
|  |  | 
|  | // Transfer LiveVariables states, kill / dead info. | 
|  | if (LV) { | 
|  | for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { | 
|  | MachineOperand &MO = MI->getOperand(i); | 
|  | if (MO.isReg() && MO.getReg() && | 
|  | TargetRegisterInfo::isVirtualRegister(MO.getReg())) { | 
|  | unsigned Reg = MO.getReg(); | 
|  |  | 
|  | LiveVariables::VarInfo &VI = LV->getVarInfo(Reg); | 
|  | if (MO.isDef()) { | 
|  | MachineInstr *NewMI = (Reg == WBReg) ? UpdateMI : MemMI; | 
|  | if (MO.isDead()) | 
|  | LV->addVirtualRegisterDead(Reg, NewMI); | 
|  | } | 
|  | if (MO.isUse() && MO.isKill()) { | 
|  | for (unsigned j = 0; j < 2; ++j) { | 
|  | // Look at the two new MI's in reverse order. | 
|  | MachineInstr *NewMI = NewMIs[j]; | 
|  | if (!NewMI->readsRegister(Reg)) | 
|  | continue; | 
|  | LV->addVirtualRegisterKilled(Reg, NewMI); | 
|  | if (VI.removeKill(MI)) | 
|  | VI.Kills.push_back(NewMI); | 
|  | break; | 
|  | } | 
|  | } | 
|  | } | 
|  | } | 
|  | } | 
|  |  | 
|  | MFI->insert(MBBI, NewMIs[1]); | 
|  | MFI->insert(MBBI, NewMIs[0]); | 
|  | return NewMIs[0]; | 
|  | } | 
|  |  | 
|  | // Branch analysis. | 
|  | bool | 
|  | ARMBaseInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB, | 
|  | MachineBasicBlock *&FBB, | 
|  | SmallVectorImpl<MachineOperand> &Cond, | 
|  | bool AllowModify) const { | 
|  | // If the block has no terminators, it just falls into the block after it. | 
|  | MachineBasicBlock::iterator I = MBB.end(); | 
|  | if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) | 
|  | return false; | 
|  |  | 
|  | // Get the last instruction in the block. | 
|  | MachineInstr *LastInst = I; | 
|  |  | 
|  | // If there is only one terminator instruction, process it. | 
|  | unsigned LastOpc = LastInst->getOpcode(); | 
|  | if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) { | 
|  | if (isUncondBranchOpcode(LastOpc)) { | 
|  | TBB = LastInst->getOperand(0).getMBB(); | 
|  | return false; | 
|  | } | 
|  | if (isCondBranchOpcode(LastOpc)) { | 
|  | // Block ends with fall-through condbranch. | 
|  | TBB = LastInst->getOperand(0).getMBB(); | 
|  | Cond.push_back(LastInst->getOperand(1)); | 
|  | Cond.push_back(LastInst->getOperand(2)); | 
|  | return false; | 
|  | } | 
|  | return true;  // Can't handle indirect branch. | 
|  | } | 
|  |  | 
|  | // Get the instruction before it if it is a terminator. | 
|  | MachineInstr *SecondLastInst = I; | 
|  |  | 
|  | // If there are three terminators, we don't know what sort of block this is. | 
|  | if (SecondLastInst && I != MBB.begin() && isUnpredicatedTerminator(--I)) | 
|  | return true; | 
|  |  | 
|  | // If the block ends with a B and a Bcc, handle it. | 
|  | unsigned SecondLastOpc = SecondLastInst->getOpcode(); | 
|  | if (isCondBranchOpcode(SecondLastOpc) && isUncondBranchOpcode(LastOpc)) { | 
|  | TBB =  SecondLastInst->getOperand(0).getMBB(); | 
|  | Cond.push_back(SecondLastInst->getOperand(1)); | 
|  | Cond.push_back(SecondLastInst->getOperand(2)); | 
|  | FBB = LastInst->getOperand(0).getMBB(); | 
|  | return false; | 
|  | } | 
|  |  | 
|  | // If the block ends with two unconditional branches, handle it.  The second | 
|  | // one is not executed, so remove it. | 
|  | if (isUncondBranchOpcode(SecondLastOpc) && isUncondBranchOpcode(LastOpc)) { | 
|  | TBB = SecondLastInst->getOperand(0).getMBB(); | 
|  | I = LastInst; | 
|  | if (AllowModify) | 
|  | I->eraseFromParent(); | 
|  | return false; | 
|  | } | 
|  |  | 
|  | // ...likewise if it ends with a branch table followed by an unconditional | 
|  | // branch. The branch folder can create these, and we must get rid of them for | 
|  | // correctness of Thumb constant islands. | 
|  | if (isJumpTableBranchOpcode(SecondLastOpc) && | 
|  | isUncondBranchOpcode(LastOpc)) { | 
|  | I = LastInst; | 
|  | if (AllowModify) | 
|  | I->eraseFromParent(); | 
|  | return true; | 
|  | } | 
|  |  | 
|  | // Otherwise, can't handle this. | 
|  | return true; | 
|  | } | 
|  |  | 
|  |  | 
|  | unsigned ARMBaseInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const { | 
|  | MachineBasicBlock::iterator I = MBB.end(); | 
|  | if (I == MBB.begin()) return 0; | 
|  | --I; | 
|  | if (!isUncondBranchOpcode(I->getOpcode()) && | 
|  | !isCondBranchOpcode(I->getOpcode())) | 
|  | return 0; | 
|  |  | 
|  | // Remove the branch. | 
|  | I->eraseFromParent(); | 
|  |  | 
|  | I = MBB.end(); | 
|  |  | 
|  | if (I == MBB.begin()) return 1; | 
|  | --I; | 
|  | if (!isCondBranchOpcode(I->getOpcode())) | 
|  | return 1; | 
|  |  | 
|  | // Remove the branch. | 
|  | I->eraseFromParent(); | 
|  | return 2; | 
|  | } | 
|  |  | 
|  | unsigned | 
|  | ARMBaseInstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, | 
|  | MachineBasicBlock *FBB, | 
|  | const SmallVectorImpl<MachineOperand> &Cond) const { | 
|  | // FIXME this should probably have a DebugLoc argument | 
|  | DebugLoc dl = DebugLoc::getUnknownLoc(); | 
|  |  | 
|  | ARMFunctionInfo *AFI = MBB.getParent()->getInfo<ARMFunctionInfo>(); | 
|  | int BOpc   = !AFI->isThumbFunction() | 
|  | ? ARM::B : (AFI->isThumb2Function() ? ARM::t2B : ARM::tB); | 
|  | int BccOpc = !AFI->isThumbFunction() | 
|  | ? ARM::Bcc : (AFI->isThumb2Function() ? ARM::t2Bcc : ARM::tBcc); | 
|  |  | 
|  | // Shouldn't be a fall through. | 
|  | assert(TBB && "InsertBranch must not be told to insert a fallthrough"); | 
|  | assert((Cond.size() == 2 || Cond.size() == 0) && | 
|  | "ARM branch conditions have two components!"); | 
|  |  | 
|  | if (FBB == 0) { | 
|  | if (Cond.empty()) // Unconditional branch? | 
|  | BuildMI(&MBB, dl, get(BOpc)).addMBB(TBB); | 
|  | else | 
|  | BuildMI(&MBB, dl, get(BccOpc)).addMBB(TBB) | 
|  | .addImm(Cond[0].getImm()).addReg(Cond[1].getReg()); | 
|  | return 1; | 
|  | } | 
|  |  | 
|  | // Two-way conditional branch. | 
|  | BuildMI(&MBB, dl, get(BccOpc)).addMBB(TBB) | 
|  | .addImm(Cond[0].getImm()).addReg(Cond[1].getReg()); | 
|  | BuildMI(&MBB, dl, get(BOpc)).addMBB(FBB); | 
|  | return 2; | 
|  | } | 
|  |  | 
|  | bool ARMBaseInstrInfo:: | 
|  | ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const { | 
|  | ARMCC::CondCodes CC = (ARMCC::CondCodes)(int)Cond[0].getImm(); | 
|  | Cond[0].setImm(ARMCC::getOppositeCondition(CC)); | 
|  | return false; | 
|  | } | 
|  |  | 
|  | bool ARMBaseInstrInfo:: | 
|  | PredicateInstruction(MachineInstr *MI, | 
|  | const SmallVectorImpl<MachineOperand> &Pred) const { | 
|  | unsigned Opc = MI->getOpcode(); | 
|  | if (isUncondBranchOpcode(Opc)) { | 
|  | MI->setDesc(get(getMatchingCondBranchOpcode(Opc))); | 
|  | MI->addOperand(MachineOperand::CreateImm(Pred[0].getImm())); | 
|  | MI->addOperand(MachineOperand::CreateReg(Pred[1].getReg(), false)); | 
|  | return true; | 
|  | } | 
|  |  | 
|  | int PIdx = MI->findFirstPredOperandIdx(); | 
|  | if (PIdx != -1) { | 
|  | MachineOperand &PMO = MI->getOperand(PIdx); | 
|  | PMO.setImm(Pred[0].getImm()); | 
|  | MI->getOperand(PIdx+1).setReg(Pred[1].getReg()); | 
|  | return true; | 
|  | } | 
|  | return false; | 
|  | } | 
|  |  | 
|  | bool ARMBaseInstrInfo:: | 
|  | SubsumesPredicate(const SmallVectorImpl<MachineOperand> &Pred1, | 
|  | const SmallVectorImpl<MachineOperand> &Pred2) const { | 
|  | if (Pred1.size() > 2 || Pred2.size() > 2) | 
|  | return false; | 
|  |  | 
|  | ARMCC::CondCodes CC1 = (ARMCC::CondCodes)Pred1[0].getImm(); | 
|  | ARMCC::CondCodes CC2 = (ARMCC::CondCodes)Pred2[0].getImm(); | 
|  | if (CC1 == CC2) | 
|  | return true; | 
|  |  | 
|  | switch (CC1) { | 
|  | default: | 
|  | return false; | 
|  | case ARMCC::AL: | 
|  | return true; | 
|  | case ARMCC::HS: | 
|  | return CC2 == ARMCC::HI; | 
|  | case ARMCC::LS: | 
|  | return CC2 == ARMCC::LO || CC2 == ARMCC::EQ; | 
|  | case ARMCC::GE: | 
|  | return CC2 == ARMCC::GT; | 
|  | case ARMCC::LE: | 
|  | return CC2 == ARMCC::LT; | 
|  | } | 
|  | } | 
|  |  | 
|  | bool ARMBaseInstrInfo::DefinesPredicate(MachineInstr *MI, | 
|  | std::vector<MachineOperand> &Pred) const { | 
|  | const TargetInstrDesc &TID = MI->getDesc(); | 
|  | if (!TID.getImplicitDefs() && !TID.hasOptionalDef()) | 
|  | return false; | 
|  |  | 
|  | bool Found = false; | 
|  | for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { | 
|  | const MachineOperand &MO = MI->getOperand(i); | 
|  | if (MO.isReg() && MO.getReg() == ARM::CPSR) { | 
|  | Pred.push_back(MO); | 
|  | Found = true; | 
|  | } | 
|  | } | 
|  |  | 
|  | return Found; | 
|  | } | 
|  |  | 
|  |  | 
|  | /// FIXME: Works around a gcc miscompilation with -fstrict-aliasing | 
|  | static unsigned getNumJTEntries(const std::vector<MachineJumpTableEntry> &JT, | 
|  | unsigned JTI) DISABLE_INLINE; | 
|  | static unsigned getNumJTEntries(const std::vector<MachineJumpTableEntry> &JT, | 
|  | unsigned JTI) { | 
|  | return JT[JTI].MBBs.size(); | 
|  | } | 
|  |  | 
|  | /// GetInstSize - Return the size of the specified MachineInstr. | 
|  | /// | 
|  | unsigned ARMBaseInstrInfo::GetInstSizeInBytes(const MachineInstr *MI) const { | 
|  | const MachineBasicBlock &MBB = *MI->getParent(); | 
|  | const MachineFunction *MF = MBB.getParent(); | 
|  | const TargetAsmInfo *TAI = MF->getTarget().getTargetAsmInfo(); | 
|  |  | 
|  | // Basic size info comes from the TSFlags field. | 
|  | const TargetInstrDesc &TID = MI->getDesc(); | 
|  | unsigned TSFlags = TID.TSFlags; | 
|  |  | 
|  | unsigned Opc = MI->getOpcode(); | 
|  | switch ((TSFlags & ARMII::SizeMask) >> ARMII::SizeShift) { | 
|  | default: { | 
|  | // If this machine instr is an inline asm, measure it. | 
|  | if (MI->getOpcode() == ARM::INLINEASM) | 
|  | return getInlineAsmLength(MI->getOperand(0).getSymbolName(), *TAI); | 
|  | if (MI->isLabel()) | 
|  | return 0; | 
|  | switch (Opc) { | 
|  | default: | 
|  | llvm_unreachable("Unknown or unset size field for instr!"); | 
|  | case TargetInstrInfo::IMPLICIT_DEF: | 
|  | case TargetInstrInfo::DECLARE: | 
|  | case TargetInstrInfo::DBG_LABEL: | 
|  | case TargetInstrInfo::EH_LABEL: | 
|  | return 0; | 
|  | } | 
|  | break; | 
|  | } | 
|  | case ARMII::Size8Bytes: return 8;          // ARM instruction x 2. | 
|  | case ARMII::Size4Bytes: return 4;          // ARM / Thumb2 instruction. | 
|  | case ARMII::Size2Bytes: return 2;          // Thumb1 instruction. | 
|  | case ARMII::SizeSpecial: { | 
|  | switch (Opc) { | 
|  | case ARM::CONSTPOOL_ENTRY: | 
|  | // If this machine instr is a constant pool entry, its size is recorded as | 
|  | // operand #2. | 
|  | return MI->getOperand(2).getImm(); | 
|  | case ARM::Int_eh_sjlj_setjmp: | 
|  | return 12; | 
|  | case ARM::BR_JTr: | 
|  | case ARM::BR_JTm: | 
|  | case ARM::BR_JTadd: | 
|  | case ARM::tBR_JTr: | 
|  | case ARM::t2BR_JT: | 
|  | case ARM::t2TBB: | 
|  | case ARM::t2TBH: { | 
|  | // These are jumptable branches, i.e. a branch followed by an inlined | 
|  | // jumptable. The size is 4 + 4 * number of entries. For TBB, each | 
|  | // entry is one byte; TBH two byte each. | 
|  | unsigned EntrySize = (Opc == ARM::t2TBB) | 
|  | ? 1 : ((Opc == ARM::t2TBH) ? 2 : 4); | 
|  | unsigned NumOps = TID.getNumOperands(); | 
|  | MachineOperand JTOP = | 
|  | MI->getOperand(NumOps - (TID.isPredicable() ? 3 : 2)); | 
|  | unsigned JTI = JTOP.getIndex(); | 
|  | const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo(); | 
|  | const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables(); | 
|  | assert(JTI < JT.size()); | 
|  | // Thumb instructions are 2 byte aligned, but JT entries are 4 byte | 
|  | // 4 aligned. The assembler / linker may add 2 byte padding just before | 
|  | // the JT entries.  The size does not include this padding; the | 
|  | // constant islands pass does separate bookkeeping for it. | 
|  | // FIXME: If we know the size of the function is less than (1 << 16) *2 | 
|  | // bytes, we can use 16-bit entries instead. Then there won't be an | 
|  | // alignment issue. | 
|  | unsigned InstSize = (Opc == ARM::tBR_JTr || Opc == ARM::t2BR_JT) ? 2 : 4; | 
|  | unsigned NumEntries = getNumJTEntries(JT, JTI); | 
|  | if (Opc == ARM::t2TBB && (NumEntries & 1)) | 
|  | // Make sure the instruction that follows TBB is 2-byte aligned. | 
|  | // FIXME: Constant island pass should insert an "ALIGN" instruction | 
|  | // instead. | 
|  | ++NumEntries; | 
|  | return NumEntries * EntrySize + InstSize; | 
|  | } | 
|  | default: | 
|  | // Otherwise, pseudo-instruction sizes are zero. | 
|  | return 0; | 
|  | } | 
|  | } | 
|  | } | 
|  | return 0; // Not reached | 
|  | } | 
|  |  | 
|  | /// Return true if the instruction is a register to register move and | 
|  | /// leave the source and dest operands in the passed parameters. | 
|  | /// | 
|  | bool | 
|  | ARMBaseInstrInfo::isMoveInstr(const MachineInstr &MI, | 
|  | unsigned &SrcReg, unsigned &DstReg, | 
|  | unsigned& SrcSubIdx, unsigned& DstSubIdx) const { | 
|  | SrcSubIdx = DstSubIdx = 0; // No sub-registers. | 
|  |  | 
|  | switch (MI.getOpcode()) { | 
|  | default: break; | 
|  | case ARM::FCPYS: | 
|  | case ARM::FCPYD: | 
|  | case ARM::VMOVD: | 
|  | case  ARM::VMOVQ: { | 
|  | SrcReg = MI.getOperand(1).getReg(); | 
|  | DstReg = MI.getOperand(0).getReg(); | 
|  | return true; | 
|  | } | 
|  | case ARM::MOVr: | 
|  | case ARM::tMOVr: | 
|  | case ARM::tMOVgpr2tgpr: | 
|  | case ARM::tMOVtgpr2gpr: | 
|  | case ARM::tMOVgpr2gpr: | 
|  | case ARM::t2MOVr: { | 
|  | assert(MI.getDesc().getNumOperands() >= 2 && | 
|  | MI.getOperand(0).isReg() && | 
|  | MI.getOperand(1).isReg() && | 
|  | "Invalid ARM MOV instruction"); | 
|  | SrcReg = MI.getOperand(1).getReg(); | 
|  | DstReg = MI.getOperand(0).getReg(); | 
|  | return true; | 
|  | } | 
|  | } | 
|  |  | 
|  | return false; | 
|  | } | 
|  |  | 
|  | unsigned | 
|  | ARMBaseInstrInfo::isLoadFromStackSlot(const MachineInstr *MI, | 
|  | int &FrameIndex) const { | 
|  | switch (MI->getOpcode()) { | 
|  | default: break; | 
|  | case ARM::LDR: | 
|  | case ARM::t2LDRs:  // FIXME: don't use t2LDRs to access frame. | 
|  | if (MI->getOperand(1).isFI() && | 
|  | MI->getOperand(2).isReg() && | 
|  | MI->getOperand(3).isImm() && | 
|  | MI->getOperand(2).getReg() == 0 && | 
|  | MI->getOperand(3).getImm() == 0) { | 
|  | FrameIndex = MI->getOperand(1).getIndex(); | 
|  | return MI->getOperand(0).getReg(); | 
|  | } | 
|  | break; | 
|  | case ARM::t2LDRi12: | 
|  | case ARM::tRestore: | 
|  | if (MI->getOperand(1).isFI() && | 
|  | MI->getOperand(2).isImm() && | 
|  | MI->getOperand(2).getImm() == 0) { | 
|  | FrameIndex = MI->getOperand(1).getIndex(); | 
|  | return MI->getOperand(0).getReg(); | 
|  | } | 
|  | break; | 
|  | case ARM::FLDD: | 
|  | case ARM::FLDS: | 
|  | if (MI->getOperand(1).isFI() && | 
|  | MI->getOperand(2).isImm() && | 
|  | MI->getOperand(2).getImm() == 0) { | 
|  | FrameIndex = MI->getOperand(1).getIndex(); | 
|  | return MI->getOperand(0).getReg(); | 
|  | } | 
|  | break; | 
|  | } | 
|  |  | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | unsigned | 
|  | ARMBaseInstrInfo::isStoreToStackSlot(const MachineInstr *MI, | 
|  | int &FrameIndex) const { | 
|  | switch (MI->getOpcode()) { | 
|  | default: break; | 
|  | case ARM::STR: | 
|  | case ARM::t2STRs: // FIXME: don't use t2STRs to access frame. | 
|  | if (MI->getOperand(1).isFI() && | 
|  | MI->getOperand(2).isReg() && | 
|  | MI->getOperand(3).isImm() && | 
|  | MI->getOperand(2).getReg() == 0 && | 
|  | MI->getOperand(3).getImm() == 0) { | 
|  | FrameIndex = MI->getOperand(1).getIndex(); | 
|  | return MI->getOperand(0).getReg(); | 
|  | } | 
|  | break; | 
|  | case ARM::t2STRi12: | 
|  | case ARM::tSpill: | 
|  | if (MI->getOperand(1).isFI() && | 
|  | MI->getOperand(2).isImm() && | 
|  | MI->getOperand(2).getImm() == 0) { | 
|  | FrameIndex = MI->getOperand(1).getIndex(); | 
|  | return MI->getOperand(0).getReg(); | 
|  | } | 
|  | break; | 
|  | case ARM::FSTD: | 
|  | case  ARM::FSTS: | 
|  | if (MI->getOperand(1).isFI() && | 
|  | MI->getOperand(2).isImm() && | 
|  | MI->getOperand(2).getImm() == 0) { | 
|  | FrameIndex = MI->getOperand(1).getIndex(); | 
|  | return MI->getOperand(0).getReg(); | 
|  | } | 
|  | break; | 
|  | } | 
|  |  | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | bool | 
|  | ARMBaseInstrInfo::copyRegToReg(MachineBasicBlock &MBB, | 
|  | MachineBasicBlock::iterator I, | 
|  | unsigned DestReg, unsigned SrcReg, | 
|  | const TargetRegisterClass *DestRC, | 
|  | const TargetRegisterClass *SrcRC) const { | 
|  | DebugLoc DL = DebugLoc::getUnknownLoc(); | 
|  | if (I != MBB.end()) DL = I->getDebugLoc(); | 
|  |  | 
|  | if (DestRC != SrcRC) { | 
|  | // Not yet supported! | 
|  | return false; | 
|  | } | 
|  |  | 
|  | if (DestRC == ARM::GPRRegisterClass) | 
|  | AddDefaultCC(AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::MOVr), | 
|  | DestReg).addReg(SrcReg))); | 
|  | else if (DestRC == ARM::SPRRegisterClass) | 
|  | AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::FCPYS), DestReg) | 
|  | .addReg(SrcReg)); | 
|  | else if (DestRC == ARM::DPRRegisterClass) | 
|  | AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::FCPYD), DestReg) | 
|  | .addReg(SrcReg)); | 
|  | else if (DestRC == ARM::QPRRegisterClass) | 
|  | BuildMI(MBB, I, DL, get(ARM::VMOVQ), DestReg).addReg(SrcReg); | 
|  | else | 
|  | return false; | 
|  |  | 
|  | return true; | 
|  | } | 
|  |  | 
|  | void ARMBaseInstrInfo:: | 
|  | storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I, | 
|  | unsigned SrcReg, bool isKill, int FI, | 
|  | const TargetRegisterClass *RC) const { | 
|  | DebugLoc DL = DebugLoc::getUnknownLoc(); | 
|  | if (I != MBB.end()) DL = I->getDebugLoc(); | 
|  |  | 
|  | if (RC == ARM::GPRRegisterClass) { | 
|  | AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::STR)) | 
|  | .addReg(SrcReg, getKillRegState(isKill)) | 
|  | .addFrameIndex(FI).addReg(0).addImm(0)); | 
|  | } else if (RC == ARM::DPRRegisterClass) { | 
|  | AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::FSTD)) | 
|  | .addReg(SrcReg, getKillRegState(isKill)) | 
|  | .addFrameIndex(FI).addImm(0)); | 
|  | } else { | 
|  | assert(RC == ARM::SPRRegisterClass && "Unknown regclass!"); | 
|  | AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::FSTS)) | 
|  | .addReg(SrcReg, getKillRegState(isKill)) | 
|  | .addFrameIndex(FI).addImm(0)); | 
|  | } | 
|  | } | 
|  |  | 
|  | void ARMBaseInstrInfo:: | 
|  | loadRegFromStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I, | 
|  | unsigned DestReg, int FI, | 
|  | const TargetRegisterClass *RC) const { | 
|  | DebugLoc DL = DebugLoc::getUnknownLoc(); | 
|  | if (I != MBB.end()) DL = I->getDebugLoc(); | 
|  |  | 
|  | if (RC == ARM::GPRRegisterClass) { | 
|  | AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::LDR), DestReg) | 
|  | .addFrameIndex(FI).addReg(0).addImm(0)); | 
|  | } else if (RC == ARM::DPRRegisterClass) { | 
|  | AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::FLDD), DestReg) | 
|  | .addFrameIndex(FI).addImm(0)); | 
|  | } else { | 
|  | assert(RC == ARM::SPRRegisterClass && "Unknown regclass!"); | 
|  | AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::FLDS), DestReg) | 
|  | .addFrameIndex(FI).addImm(0)); | 
|  | } | 
|  | } | 
|  |  | 
|  | MachineInstr *ARMBaseInstrInfo:: | 
|  | foldMemoryOperandImpl(MachineFunction &MF, MachineInstr *MI, | 
|  | const SmallVectorImpl<unsigned> &Ops, int FI) const { | 
|  | if (Ops.size() != 1) return NULL; | 
|  |  | 
|  | unsigned OpNum = Ops[0]; | 
|  | unsigned Opc = MI->getOpcode(); | 
|  | MachineInstr *NewMI = NULL; | 
|  | if (Opc == ARM::MOVr || Opc == ARM::t2MOVr) { | 
|  | // If it is updating CPSR, then it cannot be folded. | 
|  | if (MI->getOperand(4).getReg() != ARM::CPSR || MI->getOperand(4).isDead()) { | 
|  | unsigned Pred = MI->getOperand(2).getImm(); | 
|  | unsigned PredReg = MI->getOperand(3).getReg(); | 
|  | if (OpNum == 0) { // move -> store | 
|  | unsigned SrcReg = MI->getOperand(1).getReg(); | 
|  | bool isKill = MI->getOperand(1).isKill(); | 
|  | bool isUndef = MI->getOperand(1).isUndef(); | 
|  | if (Opc == ARM::MOVr) | 
|  | NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::STR)) | 
|  | .addReg(SrcReg, getKillRegState(isKill) | getUndefRegState(isUndef)) | 
|  | .addFrameIndex(FI).addReg(0).addImm(0).addImm(Pred).addReg(PredReg); | 
|  | else // ARM::t2MOVr | 
|  | NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::t2STRi12)) | 
|  | .addReg(SrcReg, getKillRegState(isKill) | getUndefRegState(isUndef)) | 
|  | .addFrameIndex(FI).addImm(0).addImm(Pred).addReg(PredReg); | 
|  | } else {          // move -> load | 
|  | unsigned DstReg = MI->getOperand(0).getReg(); | 
|  | bool isDead = MI->getOperand(0).isDead(); | 
|  | bool isUndef = MI->getOperand(0).isUndef(); | 
|  | if (Opc == ARM::MOVr) | 
|  | NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::LDR)) | 
|  | .addReg(DstReg, | 
|  | RegState::Define | | 
|  | getDeadRegState(isDead) | | 
|  | getUndefRegState(isUndef)) | 
|  | .addFrameIndex(FI).addReg(0).addImm(0).addImm(Pred).addReg(PredReg); | 
|  | else // ARM::t2MOVr | 
|  | NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::t2LDRi12)) | 
|  | .addReg(DstReg, | 
|  | RegState::Define | | 
|  | getDeadRegState(isDead) | | 
|  | getUndefRegState(isUndef)) | 
|  | .addFrameIndex(FI).addImm(0).addImm(Pred).addReg(PredReg); | 
|  | } | 
|  | } | 
|  | } | 
|  | else if (Opc == ARM::FCPYS) { | 
|  | unsigned Pred = MI->getOperand(2).getImm(); | 
|  | unsigned PredReg = MI->getOperand(3).getReg(); | 
|  | if (OpNum == 0) { // move -> store | 
|  | unsigned SrcReg = MI->getOperand(1).getReg(); | 
|  | bool isKill = MI->getOperand(1).isKill(); | 
|  | bool isUndef = MI->getOperand(1).isUndef(); | 
|  | NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::FSTS)) | 
|  | .addReg(SrcReg, getKillRegState(isKill) | getUndefRegState(isUndef)) | 
|  | .addFrameIndex(FI) | 
|  | .addImm(0).addImm(Pred).addReg(PredReg); | 
|  | } else {          // move -> load | 
|  | unsigned DstReg = MI->getOperand(0).getReg(); | 
|  | bool isDead = MI->getOperand(0).isDead(); | 
|  | bool isUndef = MI->getOperand(0).isUndef(); | 
|  | NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::FLDS)) | 
|  | .addReg(DstReg, | 
|  | RegState::Define | | 
|  | getDeadRegState(isDead) | | 
|  | getUndefRegState(isUndef)) | 
|  | .addFrameIndex(FI).addImm(0).addImm(Pred).addReg(PredReg); | 
|  | } | 
|  | } | 
|  | else if (Opc == ARM::FCPYD) { | 
|  | unsigned Pred = MI->getOperand(2).getImm(); | 
|  | unsigned PredReg = MI->getOperand(3).getReg(); | 
|  | if (OpNum == 0) { // move -> store | 
|  | unsigned SrcReg = MI->getOperand(1).getReg(); | 
|  | bool isKill = MI->getOperand(1).isKill(); | 
|  | bool isUndef = MI->getOperand(1).isUndef(); | 
|  | NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::FSTD)) | 
|  | .addReg(SrcReg, getKillRegState(isKill) | getUndefRegState(isUndef)) | 
|  | .addFrameIndex(FI).addImm(0).addImm(Pred).addReg(PredReg); | 
|  | } else {          // move -> load | 
|  | unsigned DstReg = MI->getOperand(0).getReg(); | 
|  | bool isDead = MI->getOperand(0).isDead(); | 
|  | bool isUndef = MI->getOperand(0).isUndef(); | 
|  | NewMI = BuildMI(MF, MI->getDebugLoc(), get(ARM::FLDD)) | 
|  | .addReg(DstReg, | 
|  | RegState::Define | | 
|  | getDeadRegState(isDead) | | 
|  | getUndefRegState(isUndef)) | 
|  | .addFrameIndex(FI).addImm(0).addImm(Pred).addReg(PredReg); | 
|  | } | 
|  | } | 
|  |  | 
|  | return NewMI; | 
|  | } | 
|  |  | 
|  | MachineInstr* | 
|  | ARMBaseInstrInfo::foldMemoryOperandImpl(MachineFunction &MF, | 
|  | MachineInstr* MI, | 
|  | const SmallVectorImpl<unsigned> &Ops, | 
|  | MachineInstr* LoadMI) const { | 
|  | // FIXME | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | bool | 
|  | ARMBaseInstrInfo::canFoldMemoryOperand(const MachineInstr *MI, | 
|  | const SmallVectorImpl<unsigned> &Ops) const { | 
|  | if (Ops.size() != 1) return false; | 
|  |  | 
|  | unsigned Opc = MI->getOpcode(); | 
|  | if (Opc == ARM::MOVr || Opc == ARM::t2MOVr) { | 
|  | // If it is updating CPSR, then it cannot be folded. | 
|  | return MI->getOperand(4).getReg() != ARM::CPSR ||MI->getOperand(4).isDead(); | 
|  | } else if (Opc == ARM::FCPYS || Opc == ARM::FCPYD) { | 
|  | return true; | 
|  | } else if (Opc == ARM::VMOVD || Opc == ARM::VMOVQ) { | 
|  | return false; // FIXME | 
|  | } | 
|  |  | 
|  | return false; | 
|  | } | 
|  |  | 
|  | int llvm::getMatchingCondBranchOpcode(int Opc) { | 
|  | if (Opc == ARM::B) | 
|  | return ARM::Bcc; | 
|  | else if (Opc == ARM::tB) | 
|  | return ARM::tBcc; | 
|  | else if (Opc == ARM::t2B) | 
|  | return ARM::t2Bcc; | 
|  |  | 
|  | llvm_unreachable("Unknown unconditional branch opcode!"); | 
|  | return 0; | 
|  | } | 
|  |  | 
|  |  | 
|  | void llvm::emitARMRegPlusImmediate(MachineBasicBlock &MBB, | 
|  | MachineBasicBlock::iterator &MBBI, DebugLoc dl, | 
|  | unsigned DestReg, unsigned BaseReg, int NumBytes, | 
|  | ARMCC::CondCodes Pred, unsigned PredReg, | 
|  | const ARMBaseInstrInfo &TII) { | 
|  | bool isSub = NumBytes < 0; | 
|  | if (isSub) NumBytes = -NumBytes; | 
|  |  | 
|  | while (NumBytes) { | 
|  | unsigned RotAmt = ARM_AM::getSOImmValRotate(NumBytes); | 
|  | unsigned ThisVal = NumBytes & ARM_AM::rotr32(0xFF, RotAmt); | 
|  | assert(ThisVal && "Didn't extract field correctly"); | 
|  |  | 
|  | // We will handle these bits from offset, clear them. | 
|  | NumBytes &= ~ThisVal; | 
|  |  | 
|  | assert(ARM_AM::getSOImmVal(ThisVal) != -1 && "Bit extraction didn't work?"); | 
|  |  | 
|  | // Build the new ADD / SUB. | 
|  | unsigned Opc = isSub ? ARM::SUBri : ARM::ADDri; | 
|  | BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg) | 
|  | .addReg(BaseReg, RegState::Kill).addImm(ThisVal) | 
|  | .addImm((unsigned)Pred).addReg(PredReg).addReg(0); | 
|  | BaseReg = DestReg; | 
|  | } | 
|  | } | 
|  |  | 
|  | int llvm::rewriteARMFrameIndex(MachineInstr &MI, unsigned FrameRegIdx, | 
|  | unsigned FrameReg, int Offset, | 
|  | const ARMBaseInstrInfo &TII) { | 
|  | unsigned Opcode = MI.getOpcode(); | 
|  | const TargetInstrDesc &Desc = MI.getDesc(); | 
|  | unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask); | 
|  | bool isSub = false; | 
|  |  | 
|  | // Memory operands in inline assembly always use AddrMode2. | 
|  | if (Opcode == ARM::INLINEASM) | 
|  | AddrMode = ARMII::AddrMode2; | 
|  |  | 
|  | if (Opcode == ARM::ADDri) { | 
|  | Offset += MI.getOperand(FrameRegIdx+1).getImm(); | 
|  | if (Offset == 0) { | 
|  | // Turn it into a move. | 
|  | MI.setDesc(TII.get(ARM::MOVr)); | 
|  | MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false); | 
|  | MI.RemoveOperand(FrameRegIdx+1); | 
|  | return 0; | 
|  | } else if (Offset < 0) { | 
|  | Offset = -Offset; | 
|  | isSub = true; | 
|  | MI.setDesc(TII.get(ARM::SUBri)); | 
|  | } | 
|  |  | 
|  | // Common case: small offset, fits into instruction. | 
|  | if (ARM_AM::getSOImmVal(Offset) != -1) { | 
|  | // Replace the FrameIndex with sp / fp | 
|  | MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false); | 
|  | MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset); | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | // Otherwise, pull as much of the immedidate into this ADDri/SUBri | 
|  | // as possible. | 
|  | unsigned RotAmt = ARM_AM::getSOImmValRotate(Offset); | 
|  | unsigned ThisImmVal = Offset & ARM_AM::rotr32(0xFF, RotAmt); | 
|  |  | 
|  | // We will handle these bits from offset, clear them. | 
|  | Offset &= ~ThisImmVal; | 
|  |  | 
|  | // Get the properly encoded SOImmVal field. | 
|  | assert(ARM_AM::getSOImmVal(ThisImmVal) != -1 && | 
|  | "Bit extraction didn't work?"); | 
|  | MI.getOperand(FrameRegIdx+1).ChangeToImmediate(ThisImmVal); | 
|  | } else { | 
|  | unsigned ImmIdx = 0; | 
|  | int InstrOffs = 0; | 
|  | unsigned NumBits = 0; | 
|  | unsigned Scale = 1; | 
|  | switch (AddrMode) { | 
|  | case ARMII::AddrMode2: { | 
|  | ImmIdx = FrameRegIdx+2; | 
|  | InstrOffs = ARM_AM::getAM2Offset(MI.getOperand(ImmIdx).getImm()); | 
|  | if (ARM_AM::getAM2Op(MI.getOperand(ImmIdx).getImm()) == ARM_AM::sub) | 
|  | InstrOffs *= -1; | 
|  | NumBits = 12; | 
|  | break; | 
|  | } | 
|  | case ARMII::AddrMode3: { | 
|  | ImmIdx = FrameRegIdx+2; | 
|  | InstrOffs = ARM_AM::getAM3Offset(MI.getOperand(ImmIdx).getImm()); | 
|  | if (ARM_AM::getAM3Op(MI.getOperand(ImmIdx).getImm()) == ARM_AM::sub) | 
|  | InstrOffs *= -1; | 
|  | NumBits = 8; | 
|  | break; | 
|  | } | 
|  | case ARMII::AddrMode5: { | 
|  | ImmIdx = FrameRegIdx+1; | 
|  | InstrOffs = ARM_AM::getAM5Offset(MI.getOperand(ImmIdx).getImm()); | 
|  | if (ARM_AM::getAM5Op(MI.getOperand(ImmIdx).getImm()) == ARM_AM::sub) | 
|  | InstrOffs *= -1; | 
|  | NumBits = 8; | 
|  | Scale = 4; | 
|  | break; | 
|  | } | 
|  | default: | 
|  | llvm_unreachable("Unsupported addressing mode!"); | 
|  | break; | 
|  | } | 
|  |  | 
|  | Offset += InstrOffs * Scale; | 
|  | assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!"); | 
|  | if (Offset < 0) { | 
|  | Offset = -Offset; | 
|  | isSub = true; | 
|  | } | 
|  |  | 
|  | // Attempt to fold address comp. if opcode has offset bits | 
|  | if (NumBits > 0) { | 
|  | // Common case: small offset, fits into instruction. | 
|  | MachineOperand &ImmOp = MI.getOperand(ImmIdx); | 
|  | int ImmedOffset = Offset / Scale; | 
|  | unsigned Mask = (1 << NumBits) - 1; | 
|  | if ((unsigned)Offset <= Mask * Scale) { | 
|  | // Replace the FrameIndex with sp | 
|  | MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false); | 
|  | if (isSub) | 
|  | ImmedOffset |= 1 << NumBits; | 
|  | ImmOp.ChangeToImmediate(ImmedOffset); | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | // Otherwise, it didn't fit. Pull in what we can to simplify the immed. | 
|  | ImmedOffset = ImmedOffset & Mask; | 
|  | if (isSub) | 
|  | ImmedOffset |= 1 << NumBits; | 
|  | ImmOp.ChangeToImmediate(ImmedOffset); | 
|  | Offset &= ~(Mask*Scale); | 
|  | } | 
|  | } | 
|  |  | 
|  | return (isSub) ? -Offset : Offset; | 
|  | } |