#include "llvm/Target/TargetMachine.h"
using namespace llvm;
+unsigned FastISel::getRegForValue(Value *V, DenseMap<const Value*, unsigned> &ValueMap) {
+ unsigned &Reg = ValueMap[V];
+ if (Reg != 0)
+ return Reg;
+
+ MVT::SimpleValueType VT = TLI.getValueType(V->getType()).getSimpleVT();
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
+ if (CI->getValue().getActiveBits() > 64)
+ return 0;
+ Reg = FastEmit_i(VT, VT, ISD::Constant, CI->getZExtValue());
+ } else if (ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
+ Reg = FastEmit_f(VT, VT, ISD::ConstantFP, CF);
+
+ if (!Reg) {
+ const APFloat &Flt = CF->getValueAPF();
+ MVT IntVT = TLI.getPointerTy();
+
+ uint64_t x[2];
+ uint32_t IntBitWidth = IntVT.getSizeInBits();
+ if (Flt.convertToInteger(x, IntBitWidth, /*isSigned=*/true,
+ APFloat::rmTowardZero) != APFloat::opOK)
+ return 0;
+ APInt IntVal(IntBitWidth, 2, x);
+
+ unsigned IntegerReg = FastEmit_i(IntVT.getSimpleVT(), IntVT.getSimpleVT(),
+ ISD::Constant, IntVal.getZExtValue());
+ if (IntegerReg == 0)
+ return 0;
+ Reg = FastEmit_r(IntVT.getSimpleVT(), VT, ISD::SINT_TO_FP, IntegerReg);
+ if (Reg == 0)
+ return 0;
+ }
+ }
+
+ return Reg;
+}
+
/// SelectBinaryOp - Select and emit code for a binary operator instruction,
/// which has an opcode which directly corresponds to the given ISD opcode.
///
bool FastISel::SelectBinaryOp(Instruction *I, ISD::NodeType ISDOpcode,
DenseMap<const Value*, unsigned> &ValueMap) {
- unsigned Op0 = ValueMap[I->getOperand(0)];
- unsigned Op1 = ValueMap[I->getOperand(1)];
- if (Op0 == 0 || Op1 == 0)
- // Unhandled operand. Halt "fast" selection and bail.
- return false;
-
MVT VT = MVT::getMVT(I->getType(), /*HandleUnknown=*/true);
if (VT == MVT::Other || !VT.isSimple())
// Unhandled type. Halt "fast" selection and bail.
return false;
+ // We only handle legal types. For example, on x86-32 the instruction
+ // selector contains all of the 64-bit instructions from x86-64,
+ // under the assumption that i64 won't be used if the target doesn't
+ // support it.
+ if (!TLI.isTypeLegal(VT))
+ return false;
- unsigned ResultReg = FastEmit_rr(VT.getSimpleVT(), ISDOpcode, Op0, Op1);
+ unsigned Op0 = getRegForValue(I->getOperand(0), ValueMap);
+ if (Op0 == 0)
+ // Unhandled operand. Halt "fast" selection and bail.
+ return false;
+
+ // Check if the second operand is a constant and handle it appropriately.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ unsigned ResultReg = FastEmit_ri(VT.getSimpleVT(), VT.getSimpleVT(),
+ ISDOpcode, Op0, CI->getZExtValue());
+ if (ResultReg != 0) {
+ // We successfully emitted code for the given LLVM Instruction.
+ ValueMap[I] = ResultReg;
+ return true;
+ }
+ }
+
+ // Check if the second operand is a constant float.
+ if (ConstantFP *CF = dyn_cast<ConstantFP>(I->getOperand(1))) {
+ unsigned ResultReg = FastEmit_rf(VT.getSimpleVT(), VT.getSimpleVT(),
+ ISDOpcode, Op0, CF);
+ if (ResultReg != 0) {
+ // We successfully emitted code for the given LLVM Instruction.
+ ValueMap[I] = ResultReg;
+ return true;
+ }
+ }
+
+ unsigned Op1 = getRegForValue(I->getOperand(1), ValueMap);
+ if (Op1 == 0)
+ // Unhandled operand. Halt "fast" selection and bail.
+ return false;
+
+ // Now we have both operands in registers. Emit the instruction.
+ unsigned ResultReg = FastEmit_rr(VT.getSimpleVT(), VT.getSimpleVT(),
+ ISDOpcode, Op0, Op1);
if (ResultReg == 0)
// Target-specific code wasn't able to find a machine opcode for
// the given ISD opcode and type. Halt "fast" selection and bail.
bool FastISel::SelectGetElementPtr(Instruction *I,
DenseMap<const Value*, unsigned> &ValueMap) {
- unsigned N = ValueMap[I->getOperand(0)];
+ unsigned N = getRegForValue(I->getOperand(0), ValueMap);
if (N == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
const Type *Ty = I->getOperand(0)->getType();
- MVT VT = MVT::getMVT(Ty, /*HandleUnknown=*/true);
- MVT::SimpleValueType PtrVT = TLI.getPointerTy().getSimpleVT();
-
+ MVT::SimpleValueType VT = TLI.getPointerTy().getSimpleVT();
for (GetElementPtrInst::op_iterator OI = I->op_begin()+1, E = I->op_end();
OI != E; ++OI) {
Value *Idx = *OI;
uint64_t Offs = TD.getStructLayout(StTy)->getElementOffset(Field);
// FIXME: This can be optimized by combining the add with a
// subsequent one.
- N = FastEmit_ri(VT.getSimpleVT(), ISD::ADD, N, Offs, PtrVT);
+ N = FastEmit_ri_(VT, ISD::ADD, N, Offs, VT);
if (N == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
if (CI->getZExtValue() == 0) continue;
uint64_t Offs =
TD.getABITypeSize(Ty)*cast<ConstantInt>(CI)->getSExtValue();
- N = FastEmit_ri(VT.getSimpleVT(), ISD::ADD, N, Offs, PtrVT);
+ N = FastEmit_ri_(VT, ISD::ADD, N, Offs, VT);
if (N == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
// N = N + Idx * ElementSize;
uint64_t ElementSize = TD.getABITypeSize(Ty);
- unsigned IdxN = ValueMap[Idx];
+ unsigned IdxN = getRegForValue(Idx, ValueMap);
if (IdxN == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
// If the index is smaller or larger than intptr_t, truncate or extend
// it.
- MVT IdxVT = MVT::getMVT(Idx->getType(), /*HandleUnknown=*/true);
+ MVT IdxVT = MVT::getMVT(Idx->getType(), /*HandleUnknown=*/false);
if (IdxVT.bitsLT(VT))
- IdxN = FastEmit_r(VT.getSimpleVT(), ISD::SIGN_EXTEND, IdxN);
+ IdxN = FastEmit_r(IdxVT.getSimpleVT(), VT, ISD::SIGN_EXTEND, IdxN);
else if (IdxVT.bitsGT(VT))
- IdxN = FastEmit_r(VT.getSimpleVT(), ISD::TRUNCATE, IdxN);
+ IdxN = FastEmit_r(IdxVT.getSimpleVT(), VT, ISD::TRUNCATE, IdxN);
if (IdxN == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
- // FIXME: If multiple is power of two, turn it into a shift. The
- // optimization should be in FastEmit_ri?
- IdxN = FastEmit_ri(VT.getSimpleVT(), ISD::MUL, IdxN,
- ElementSize, PtrVT);
- if (IdxN == 0)
- // Unhandled operand. Halt "fast" selection and bail.
- return false;
- N = FastEmit_rr(VT.getSimpleVT(), ISD::ADD, N, IdxN);
+ if (ElementSize != 1) {
+ IdxN = FastEmit_ri_(VT, ISD::MUL, IdxN, ElementSize, VT);
+ if (IdxN == 0)
+ // Unhandled operand. Halt "fast" selection and bail.
+ return false;
+ }
+ N = FastEmit_rr(VT, VT, ISD::ADD, N, IdxN);
if (N == 0)
// Unhandled operand. Halt "fast" selection and bail.
return false;
return true;
}
+bool FastISel::SelectCast(Instruction *I, ISD::NodeType Opcode,
+ DenseMap<const Value*, unsigned> &ValueMap) {
+ MVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
+ MVT DstVT = TLI.getValueType(I->getType());
+
+ if (SrcVT == MVT::Other || !SrcVT.isSimple() ||
+ DstVT == MVT::Other || !DstVT.isSimple() ||
+ !TLI.isTypeLegal(SrcVT) || !TLI.isTypeLegal(DstVT))
+ // Unhandled type. Halt "fast" selection and bail.
+ return false;
+
+ unsigned InputReg = getRegForValue(I->getOperand(0), ValueMap);
+ if (!InputReg)
+ // Unhandled operand. Halt "fast" selection and bail.
+ return false;
+
+ unsigned ResultReg = FastEmit_r(SrcVT.getSimpleVT(),
+ DstVT.getSimpleVT(),
+ Opcode,
+ InputReg);
+ if (!ResultReg)
+ return false;
+
+ ValueMap[I] = ResultReg;
+ return true;
+}
+
+bool FastISel::SelectBitCast(Instruction *I,
+ DenseMap<const Value*, unsigned> &ValueMap) {
+ // If the bitcast doesn't change the type, just use the operand value.
+ if (I->getType() == I->getOperand(0)->getType()) {
+ unsigned Reg = getRegForValue(I->getOperand(0), ValueMap);
+ if (Reg == 0)
+ return false;
+ ValueMap[I] = Reg;
+ return true;
+ }
+
+ // Bitcasts of other values become reg-reg copies or BIT_CONVERT operators.
+ MVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
+ MVT DstVT = TLI.getValueType(I->getType());
+
+ if (SrcVT == MVT::Other || !SrcVT.isSimple() ||
+ DstVT == MVT::Other || !DstVT.isSimple() ||
+ !TLI.isTypeLegal(SrcVT) || !TLI.isTypeLegal(DstVT))
+ // Unhandled type. Halt "fast" selection and bail.
+ return false;
+
+ unsigned Op0 = getRegForValue(I->getOperand(0), ValueMap);
+ if (Op0 == 0)
+ // Unhandled operand. Halt "fast" selection and bail.
+ return false;
+
+ // First, try to perform the bitcast by inserting a reg-reg copy.
+ unsigned ResultReg = 0;
+ if (SrcVT.getSimpleVT() == DstVT.getSimpleVT()) {
+ TargetRegisterClass* SrcClass = TLI.getRegClassFor(SrcVT);
+ TargetRegisterClass* DstClass = TLI.getRegClassFor(DstVT);
+ ResultReg = createResultReg(DstClass);
+
+ bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg,
+ Op0, DstClass, SrcClass);
+ if (!InsertedCopy)
+ ResultReg = 0;
+ }
+
+ // If the reg-reg copy failed, select a BIT_CONVERT opcode.
+ if (!ResultReg)
+ ResultReg = FastEmit_r(SrcVT.getSimpleVT(), DstVT.getSimpleVT(),
+ ISD::BIT_CONVERT, Op0);
+
+ if (!ResultReg)
+ return false;
+
+ ValueMap[I] = ResultReg;
+ return true;
+}
+
BasicBlock::iterator
FastISel::SelectInstructions(BasicBlock::iterator Begin,
BasicBlock::iterator End,
DenseMap<const Value*, unsigned> &ValueMap,
+ DenseMap<const BasicBlock*,
+ MachineBasicBlock *> &MBBMap,
MachineBasicBlock *mbb) {
MBB = mbb;
BasicBlock::iterator I = Begin;
case Instruction::Br: {
BranchInst *BI = cast<BranchInst>(I);
- // For now, check for and handle just the most trivial case: an
- // unconditional fall-through branch.
if (BI->isUnconditional()) {
- MachineFunction::iterator NextMBB =
+ MachineFunction::iterator NextMBB =
next(MachineFunction::iterator(MBB));
- if (NextMBB != MF.end() &&
- NextMBB->getBasicBlock() == BI->getSuccessor(0)) {
- MBB->addSuccessor(NextMBB);
- break;
+ BasicBlock *LLVMSucc = BI->getSuccessor(0);
+ MachineBasicBlock *MSucc = MBBMap[LLVMSucc];
+
+ if (NextMBB != MF.end() && MSucc == NextMBB) {
+ // The unconditional fall-through case, which needs no instructions.
+ } else {
+ // The unconditional branch case.
+ TII.InsertBranch(*MBB, MSucc, NULL, SmallVector<MachineOperand, 0>());
}
+ MBB->addSuccessor(MSucc);
+ break;
}
- // Something more complicated. Halt "fast" selection and bail.
+ // Conditional branches are not handed yet.
+ // Halt "fast" selection and bail.
return I;
}
+
+ case Instruction::PHI:
+ // PHI nodes are already emitted.
+ break;
+
+ case Instruction::BitCast:
+ if (!SelectBitCast(I, ValueMap)) return I; break;
+
+ case Instruction::FPToSI:
+ if (!SelectCast(I, ISD::FP_TO_SINT, ValueMap)) return I;
+ break;
+ case Instruction::ZExt:
+ if (!SelectCast(I, ISD::ZERO_EXTEND, ValueMap)) return I;
+ break;
+ case Instruction::SExt:
+ if (!SelectCast(I, ISD::SIGN_EXTEND, ValueMap)) return I;
+ break;
+ case Instruction::Trunc:
+ if (!SelectCast(I, ISD::TRUNCATE, ValueMap)) return I;
+ break;
+ case Instruction::SIToFP:
+ if (!SelectCast(I, ISD::SINT_TO_FP, ValueMap)) return I;
+ break;
+
+ case Instruction::IntToPtr: // Deliberate fall-through.
+ case Instruction::PtrToInt: {
+ MVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
+ MVT DstVT = TLI.getValueType(I->getType());
+ if (SrcVT.getSimpleVT() == DstVT.getSimpleVT()) {
+ if (ValueMap[I->getOperand(0)]) {
+ ValueMap[I] = ValueMap[I->getOperand(0)];
+ break;
+ } else
+ // Unhandled operand
+ return I;
+ } else if (DstVT.bitsGT(SrcVT)) {
+ if (!SelectCast(I, ISD::ZERO_EXTEND, ValueMap)) return I;
+ break;
+ } else {
+ // TODO: Handle SrcVT > DstVT, where truncation is needed.
+ return I;
+ }
+ }
+
default:
// Unhandled instruction. Halt "fast" selection and bail.
return I;
}
FastISel::FastISel(MachineFunction &mf)
- : MF(mf), MRI(mf.getRegInfo()),
- TD(*mf.getTarget().getTargetData()),
- TII(*mf.getTarget().getInstrInfo()),
- TLI(*mf.getTarget().getTargetLowering()) {
+ : MF(mf),
+ MRI(mf.getRegInfo()),
+ TM(mf.getTarget()),
+ TD(*TM.getTargetData()),
+ TII(*TM.getInstrInfo()),
+ TLI(*TM.getTargetLowering()) {
}
FastISel::~FastISel() {}
-unsigned FastISel::FastEmit_(MVT::SimpleValueType, ISD::NodeType) {
+unsigned FastISel::FastEmit_(MVT::SimpleValueType, MVT::SimpleValueType, ISD::NodeType) {
return 0;
}
-unsigned FastISel::FastEmit_r(MVT::SimpleValueType, ISD::NodeType,
- unsigned /*Op0*/) {
+unsigned FastISel::FastEmit_r(MVT::SimpleValueType, MVT::SimpleValueType,
+ ISD::NodeType, unsigned /*Op0*/) {
return 0;
}
-unsigned FastISel::FastEmit_rr(MVT::SimpleValueType, ISD::NodeType,
- unsigned /*Op0*/, unsigned /*Op0*/) {
+unsigned FastISel::FastEmit_rr(MVT::SimpleValueType, MVT::SimpleValueType,
+ ISD::NodeType, unsigned /*Op0*/,
+ unsigned /*Op0*/) {
return 0;
}
-unsigned FastISel::FastEmit_i(MVT::SimpleValueType, uint64_t) {
+unsigned FastISel::FastEmit_i(MVT::SimpleValueType, MVT::SimpleValueType,
+ ISD::NodeType, uint64_t /*Imm*/) {
return 0;
}
-unsigned FastISel::FastEmit_ri(MVT::SimpleValueType, ISD::NodeType,
- unsigned /*Op0*/, uint64_t Imm,
- MVT::SimpleValueType ImmType) {
+unsigned FastISel::FastEmit_f(MVT::SimpleValueType, MVT::SimpleValueType,
+ ISD::NodeType, ConstantFP * /*FPImm*/) {
+ return 0;
+}
+
+unsigned FastISel::FastEmit_ri(MVT::SimpleValueType, MVT::SimpleValueType,
+ ISD::NodeType, unsigned /*Op0*/,
+ uint64_t /*Imm*/) {
+ return 0;
+}
+
+unsigned FastISel::FastEmit_rf(MVT::SimpleValueType, MVT::SimpleValueType,
+ ISD::NodeType, unsigned /*Op0*/,
+ ConstantFP * /*FPImm*/) {
+ return 0;
+}
+
+unsigned FastISel::FastEmit_rri(MVT::SimpleValueType, MVT::SimpleValueType,
+ ISD::NodeType,
+ unsigned /*Op0*/, unsigned /*Op1*/,
+ uint64_t /*Imm*/) {
return 0;
}
/// If that fails, it materializes the immediate into a register and try
/// FastEmit_rr instead.
unsigned FastISel::FastEmit_ri_(MVT::SimpleValueType VT, ISD::NodeType Opcode,
- unsigned Op0, uint64_t Imm,
- MVT::SimpleValueType ImmType) {
- unsigned ResultReg = 0;
+ unsigned Op0, uint64_t Imm,
+ MVT::SimpleValueType ImmType) {
// First check if immediate type is legal. If not, we can't use the ri form.
- if (TLI.getOperationAction(ISD::Constant, ImmType) == TargetLowering::Legal)
- ResultReg = FastEmit_ri(VT, Opcode, Op0, Imm, ImmType);
+ unsigned ResultReg = FastEmit_ri(VT, VT, Opcode, Op0, Imm);
if (ResultReg != 0)
return ResultReg;
- return FastEmit_rr(VT, Opcode, Op0, FastEmit_i(ImmType, Imm));
+ unsigned MaterialReg = FastEmit_i(ImmType, ImmType, ISD::Constant, Imm);
+ if (MaterialReg == 0)
+ return 0;
+ return FastEmit_rr(VT, VT, Opcode, Op0, MaterialReg);
+}
+
+/// FastEmit_rf_ - This method is a wrapper of FastEmit_ri. It first tries
+/// to emit an instruction with a floating-point immediate operand using
+/// FastEmit_rf. If that fails, it materializes the immediate into a register
+/// and try FastEmit_rr instead.
+unsigned FastISel::FastEmit_rf_(MVT::SimpleValueType VT, ISD::NodeType Opcode,
+ unsigned Op0, ConstantFP *FPImm,
+ MVT::SimpleValueType ImmType) {
+ // First check if immediate type is legal. If not, we can't use the rf form.
+ unsigned ResultReg = FastEmit_rf(VT, VT, Opcode, Op0, FPImm);
+ if (ResultReg != 0)
+ return ResultReg;
+
+ // Materialize the constant in a register.
+ unsigned MaterialReg = FastEmit_f(ImmType, ImmType, ISD::ConstantFP, FPImm);
+ if (MaterialReg == 0) {
+ // If the target doesn't have a way to directly enter a floating-point
+ // value into a register, use an alternate approach.
+ // TODO: The current approach only supports floating-point constants
+ // that can be constructed by conversion from integer values. This should
+ // be replaced by code that creates a load from a constant-pool entry,
+ // which will require some target-specific work.
+ const APFloat &Flt = FPImm->getValueAPF();
+ MVT IntVT = TLI.getPointerTy();
+
+ uint64_t x[2];
+ uint32_t IntBitWidth = IntVT.getSizeInBits();
+ if (Flt.convertToInteger(x, IntBitWidth, /*isSigned=*/true,
+ APFloat::rmTowardZero) != APFloat::opOK)
+ return 0;
+ APInt IntVal(IntBitWidth, 2, x);
+
+ unsigned IntegerReg = FastEmit_i(IntVT.getSimpleVT(), IntVT.getSimpleVT(),
+ ISD::Constant, IntVal.getZExtValue());
+ if (IntegerReg == 0)
+ return 0;
+ MaterialReg = FastEmit_r(IntVT.getSimpleVT(), VT,
+ ISD::SINT_TO_FP, IntegerReg);
+ if (MaterialReg == 0)
+ return 0;
+ }
+ return FastEmit_rr(VT, VT, Opcode, Op0, MaterialReg);
+}
+
+unsigned FastISel::createResultReg(const TargetRegisterClass* RC) {
+ return MRI.createVirtualRegister(RC);
}
unsigned FastISel::FastEmitInst_(unsigned MachineInstOpcode,
const TargetRegisterClass* RC) {
- unsigned ResultReg = MRI.createVirtualRegister(RC);
+ unsigned ResultReg = createResultReg(RC);
const TargetInstrDesc &II = TII.get(MachineInstOpcode);
BuildMI(MBB, II, ResultReg);
unsigned FastISel::FastEmitInst_r(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0) {
- unsigned ResultReg = MRI.createVirtualRegister(RC);
+ unsigned ResultReg = createResultReg(RC);
const TargetInstrDesc &II = TII.get(MachineInstOpcode);
BuildMI(MBB, II, ResultReg).addReg(Op0);
unsigned FastISel::FastEmitInst_rr(unsigned MachineInstOpcode,
const TargetRegisterClass *RC,
unsigned Op0, unsigned Op1) {
- unsigned ResultReg = MRI.createVirtualRegister(RC);
+ unsigned ResultReg = createResultReg(RC);
const TargetInstrDesc &II = TII.get(MachineInstOpcode);
BuildMI(MBB, II, ResultReg).addReg(Op0).addReg(Op1);
return ResultReg;
}
+
+unsigned FastISel::FastEmitInst_ri(unsigned MachineInstOpcode,
+ const TargetRegisterClass *RC,
+ unsigned Op0, uint64_t Imm) {
+ unsigned ResultReg = createResultReg(RC);
+ const TargetInstrDesc &II = TII.get(MachineInstOpcode);
+
+ BuildMI(MBB, II, ResultReg).addReg(Op0).addImm(Imm);
+ return ResultReg;
+}
+
+unsigned FastISel::FastEmitInst_rf(unsigned MachineInstOpcode,
+ const TargetRegisterClass *RC,
+ unsigned Op0, ConstantFP *FPImm) {
+ unsigned ResultReg = createResultReg(RC);
+ const TargetInstrDesc &II = TII.get(MachineInstOpcode);
+
+ BuildMI(MBB, II, ResultReg).addReg(Op0).addFPImm(FPImm);
+ return ResultReg;
+}
+
+unsigned FastISel::FastEmitInst_rri(unsigned MachineInstOpcode,
+ const TargetRegisterClass *RC,
+ unsigned Op0, unsigned Op1, uint64_t Imm) {
+ unsigned ResultReg = createResultReg(RC);
+ const TargetInstrDesc &II = TII.get(MachineInstOpcode);
+
+ BuildMI(MBB, II, ResultReg).addReg(Op0).addReg(Op1).addImm(Imm);
+ return ResultReg;
+}
+
+unsigned FastISel::FastEmitInst_i(unsigned MachineInstOpcode,
+ const TargetRegisterClass *RC,
+ uint64_t Imm) {
+ unsigned ResultReg = createResultReg(RC);
+ const TargetInstrDesc &II = TII.get(MachineInstOpcode);
+
+ BuildMI(MBB, II, ResultReg).addImm(Imm);
+ return ResultReg;
+}
+
+unsigned FastISel::FastEmitInst_extractsubreg(unsigned Op0, uint32_t Idx) {
+ const TargetRegisterClass* RC = MRI.getRegClass(Op0);
+ const TargetRegisterClass* SRC = *(RC->subregclasses_begin()+Idx-1);
+
+ unsigned ResultReg = createResultReg(SRC);
+ const TargetInstrDesc &II = TII.get(TargetInstrInfo::EXTRACT_SUBREG);
+
+ BuildMI(MBB, II, ResultReg).addReg(Op0).addImm(Idx);
+ return ResultReg;
+}