//===-- MSP430ISelLowering.cpp - MSP430 DAG Lowering Implementation ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the MSP430TargetLowering class.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "msp430-lower"
#include "MSP430ISelLowering.h"
#include "MSP430.h"
#include "MSP430MachineFunctionInfo.h"
#include "MSP430TargetMachine.h"
#include "MSP430Subtarget.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Intrinsics.h"
#include "llvm/CallingConv.h"
#include "llvm/GlobalVariable.h"
#include "llvm/GlobalAlias.h"
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/VectorExtras.h"
using namespace llvm;
typedef enum {
NoHWMult,
HWMultIntr,
HWMultNoIntr
} HWMultUseMode;
static cl::opt<HWMultUseMode>
HWMultMode("msp430-hwmult-mode",
cl::desc("Hardware multiplier use mode"),
cl::init(HWMultNoIntr),
cl::values(
clEnumValN(NoHWMult, "no",
"Do not use hardware multiplier"),
clEnumValN(HWMultIntr, "interrupts",
"Assume hardware multiplier can be used inside interrupts"),
clEnumValN(HWMultNoIntr, "use",
"Assume hardware multiplier cannot be used inside interrupts"),
clEnumValEnd));
MSP430TargetLowering::MSP430TargetLowering(MSP430TargetMachine &tm) :
TargetLowering(tm, new TargetLoweringObjectFileELF()),
Subtarget(*tm.getSubtargetImpl()), TM(tm) {
TD = getTargetData();
// Set up the register classes.
addRegisterClass(MVT::i8, MSP430::GR8RegisterClass);
addRegisterClass(MVT::i16, MSP430::GR16RegisterClass);
// Compute derived properties from the register classes
computeRegisterProperties();
// Provide all sorts of operation actions
// Division is expensive
setIntDivIsCheap(false);
setStackPointerRegisterToSaveRestore(MSP430::SPW);
setBooleanContents(ZeroOrOneBooleanContent);
setBooleanVectorContents(ZeroOrOneBooleanContent); // FIXME: Is this correct?
setSchedulingPreference(Sched::Latency);
// We have post-incremented loads / stores.
setIndexedLoadAction(ISD::POST_INC, MVT::i8, Legal);
setIndexedLoadAction(ISD::POST_INC, MVT::i16, Legal);
setLoadExtAction(ISD::EXTLOAD, MVT::i1, Promote);
setLoadExtAction(ISD::SEXTLOAD, MVT::i1, Promote);
setLoadExtAction(ISD::ZEXTLOAD, MVT::i1, Promote);
setLoadExtAction(ISD::SEXTLOAD, MVT::i8, Expand);
setLoadExtAction(ISD::SEXTLOAD, MVT::i16, Expand);
// We don't have any truncstores
setTruncStoreAction(MVT::i16, MVT::i8, Expand);
setOperationAction(ISD::SRA, MVT::i8, Custom);
setOperationAction(ISD::SHL, MVT::i8, Custom);
setOperationAction(ISD::SRL, MVT::i8, Custom);
setOperationAction(ISD::SRA, MVT::i16, Custom);
setOperationAction(ISD::SHL, MVT::i16, Custom);
setOperationAction(ISD::SRL, MVT::i16, Custom);
setOperationAction(ISD::ROTL, MVT::i8, Expand);
setOperationAction(ISD::ROTR, MVT::i8, Expand);
setOperationAction(ISD::ROTL, MVT::i16, Expand);
setOperationAction(ISD::ROTR, MVT::i16, Expand);
setOperationAction(ISD::GlobalAddress, MVT::i16, Custom);
setOperationAction(ISD::ExternalSymbol, MVT::i16, Custom);
setOperationAction(ISD::BlockAddress, MVT::i16, Custom);
setOperationAction(ISD::BR_JT, MVT::Other, Expand);
setOperationAction(ISD::BR_CC, MVT::i8, Custom);
setOperationAction(ISD::BR_CC, MVT::i16, Custom);
setOperationAction(ISD::BRCOND, MVT::Other, Expand);
setOperationAction(ISD::SETCC, MVT::i8, Custom);
setOperationAction(ISD::SETCC, MVT::i16, Custom);
setOperationAction(ISD::SELECT, MVT::i8, Expand);
setOperationAction(ISD::SELECT, MVT::i16, Expand);
setOperationAction(ISD::SELECT_CC, MVT::i8, Custom);
setOperationAction(ISD::SELECT_CC, MVT::i16, Custom);
setOperationAction(ISD::SIGN_EXTEND, MVT::i16, Custom);
setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i8, Expand);
setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i16, Expand);
setOperationAction(ISD::CTTZ, MVT::i8, Expand);
setOperationAction(ISD::CTTZ, MVT::i16, Expand);
setOperationAction(ISD::CTLZ, MVT::i8, Expand);
setOperationAction(ISD::CTLZ, MVT::i16, Expand);
setOperationAction(ISD::CTPOP, MVT::i8, Expand);
setOperationAction(ISD::CTPOP, MVT::i16, Expand);
setOperationAction(ISD::SHL_PARTS, MVT::i8, Expand);
setOperationAction(ISD::SHL_PARTS, MVT::i16, Expand);
setOperationAction(ISD::SRL_PARTS, MVT::i8, Expand);
setOperationAction(ISD::SRL_PARTS, MVT::i16, Expand);
setOperationAction(ISD::SRA_PARTS, MVT::i8, Expand);
setOperationAction(ISD::SRA_PARTS, MVT::i16, Expand);
setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i1, Expand);
// FIXME: Implement efficiently multiplication by a constant
setOperationAction(ISD::MUL, MVT::i8, Expand);
setOperationAction(ISD::MULHS, MVT::i8, Expand);
setOperationAction(ISD::MULHU, MVT::i8, Expand);
setOperationAction(ISD::SMUL_LOHI, MVT::i8, Expand);
setOperationAction(ISD::UMUL_LOHI, MVT::i8, Expand);
setOperationAction(ISD::MUL, MVT::i16, Expand);
setOperationAction(ISD::MULHS, MVT::i16, Expand);
setOperationAction(ISD::MULHU, MVT::i16, Expand);
setOperationAction(ISD::SMUL_LOHI, MVT::i16, Expand);
setOperationAction(ISD::UMUL_LOHI, MVT::i16, Expand);
setOperationAction(ISD::UDIV, MVT::i8, Expand);
setOperationAction(ISD::UDIVREM, MVT::i8, Expand);
setOperationAction(ISD::UREM, MVT::i8, Expand);
setOperationAction(ISD::SDIV, MVT::i8, Expand);
setOperationAction(ISD::SDIVREM, MVT::i8, Expand);
setOperationAction(ISD::SREM, MVT::i8, Expand);
setOperationAction(ISD::UDIV, MVT::i16, Expand);
setOperationAction(ISD::UDIVREM, MVT::i16, Expand);
setOperationAction(ISD::UREM, MVT::i16, Expand);
setOperationAction(ISD::SDIV, MVT::i16, Expand);
setOperationAction(ISD::SDIVREM, MVT::i16, Expand);
setOperationAction(ISD::SREM, MVT::i16, Expand);
// Libcalls names.
if (HWMultMode == HWMultIntr) {
setLibcallName(RTLIB::MUL_I8, "__mulqi3hw");
setLibcallName(RTLIB::MUL_I16, "__mulhi3hw");
} else if (HWMultMode == HWMultNoIntr) {
setLibcallName(RTLIB::MUL_I8, "__mulqi3hw_noint");
setLibcallName(RTLIB::MUL_I16, "__mulhi3hw_noint");
}
setMinFunctionAlignment(1);
setPrefFunctionAlignment(2);
}
SDValue MSP430TargetLowering::LowerOperation(SDValue Op,
SelectionDAG &DAG) const {
switch (Op.getOpcode()) {
case ISD::SHL: // FALLTHROUGH
case ISD::SRL:
case ISD::SRA: return LowerShifts(Op, DAG);
case ISD::GlobalAddress: return LowerGlobalAddress(Op, DAG);
case ISD::BlockAddress: return LowerBlockAddress(Op, DAG);
case ISD::ExternalSymbol: return LowerExternalSymbol(Op, DAG);
case ISD::SETCC: return LowerSETCC(Op, DAG);
case ISD::BR_CC: return LowerBR_CC(Op, DAG);
case ISD::SELECT_CC: return LowerSELECT_CC(Op, DAG);
case ISD::SIGN_EXTEND: return LowerSIGN_EXTEND(Op, DAG);
case ISD::RETURNADDR: return LowerRETURNADDR(Op, DAG);
case ISD::FRAMEADDR: return LowerFRAMEADDR(Op, DAG);
default:
llvm_unreachable("unimplemented operand");
return SDValue();
}
}
//===----------------------------------------------------------------------===//
// MSP430 Inline Assembly Support
//===----------------------------------------------------------------------===//
/// getConstraintType - Given a constraint letter, return the type of
/// constraint it is for this target.
TargetLowering::ConstraintType
MSP430TargetLowering::getConstraintType(const std::string &Constraint) const {
if (Constraint.size() == 1) {
switch (Constraint[0]) {
case 'r':
return C_RegisterClass;
default:
break;
}
}
return TargetLowering::getConstraintType(Constraint);
}
std::pair<unsigned, const TargetRegisterClass*>
MSP430TargetLowering::
getRegForInlineAsmConstraint(const std::string &Constraint,
EVT VT) const {
if (Constraint.size() == 1) {
// GCC Constraint Letters
switch (Constraint[0]) {
default: break;
case 'r': // GENERAL_REGS
if (VT == MVT::i8)
return std::make_pair(0U, MSP430::GR8RegisterClass);
return std::make_pair(0U, MSP430::GR16RegisterClass);
}
}
return TargetLowering::getRegForInlineAsmConstraint(Constraint, VT);
}
//===----------------------------------------------------------------------===//
// Calling Convention Implementation
//===----------------------------------------------------------------------===//
#include "MSP430GenCallingConv.inc"
SDValue
MSP430TargetLowering::LowerFormalArguments(SDValue Chain,
CallingConv::ID CallConv,
bool isVarArg,
const SmallVectorImpl<ISD::InputArg>
&Ins,
DebugLoc dl,
SelectionDAG &DAG,
SmallVectorImpl<SDValue> &InVals)
const {
switch (CallConv) {
default:
llvm_unreachable("Unsupported calling convention");
case CallingConv::C:
case CallingConv::Fast:
return LowerCCCArguments(Chain, CallConv, isVarArg, Ins, dl, DAG, InVals);
case CallingConv::MSP430_INTR:
if (Ins.empty())
return Chain;
else {
report_fatal_error("ISRs cannot have arguments");
return SDValue();
}
}
}
SDValue
MSP430TargetLowering::LowerCall(SDValue Chain, SDValue Callee,
CallingConv::ID CallConv, bool isVarArg,
bool &isTailCall,
const SmallVectorImpl<ISD::OutputArg> &Outs,
const SmallVectorImpl<SDValue> &OutVals,
const SmallVectorImpl<ISD::InputArg> &Ins,
DebugLoc dl, SelectionDAG &DAG,
SmallVectorImpl<SDValue> &InVals) const {
// MSP430 target does not yet support tail call optimization.
isTailCall = false;
switch (CallConv) {
default:
llvm_unreachable("Unsupported calling convention");
case CallingConv::Fast:
case CallingConv::C:
return LowerCCCCallTo(Chain, Callee, CallConv, isVarArg, isTailCall,
Outs, OutVals, Ins, dl, DAG, InVals);
case CallingConv::MSP430_INTR:
report_fatal_error("ISRs cannot be called directly");
return SDValue();
}
}
/// LowerCCCArguments - transform physical registers into virtual registers and
/// generate load operations for arguments places on the stack.
// FIXME: struct return stuff
// FIXME: varargs
SDValue
MSP430TargetLowering::LowerCCCArguments(SDValue Chain,
CallingConv::ID CallConv,
bool isVarArg,
const SmallVectorImpl<ISD::InputArg>
&Ins,
DebugLoc dl,
SelectionDAG &DAG,
SmallVectorImpl<SDValue> &InVals)
const {
MachineFunction &MF = DAG.getMachineFunction();
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineRegisterInfo &RegInfo = MF.getRegInfo();
// Assign locations to all of the incoming arguments.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(),
getTargetMachine(), ArgLocs, *DAG.getContext());
CCInfo.AnalyzeFormalArguments(Ins, CC_MSP430);
assert(!isVarArg && "Varargs not supported yet");
for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
if (VA.isRegLoc()) {
// Arguments passed in registers
EVT RegVT = VA.getLocVT();
switch (RegVT.getSimpleVT().SimpleTy) {
default:
{
#ifndef NDEBUG
errs() << "LowerFormalArguments Unhandled argument type: "
<< RegVT.getSimpleVT().SimpleTy << "\n";
#endif
llvm_unreachable(0);
}
case MVT::i16:
unsigned VReg =
RegInfo.createVirtualRegister(MSP430::GR16RegisterClass);
RegInfo.addLiveIn(VA.getLocReg(), VReg);
SDValue ArgValue = DAG.getCopyFromReg(Chain, dl, VReg, RegVT);
// If this is an 8-bit value, it is really passed promoted to 16
// bits. Insert an assert[sz]ext to capture this, then truncate to the
// right size.
if (VA.getLocInfo() == CCValAssign::SExt)
ArgValue = DAG.getNode(ISD::AssertSext, dl, RegVT, ArgValue,
DAG.getValueType(VA.getValVT()));
else if (VA.getLocInfo() == CCValAssign::ZExt)
ArgValue = DAG.getNode(ISD::AssertZext, dl, RegVT, ArgValue,
DAG.getValueType(VA.getValVT()));
if (VA.getLocInfo() != CCValAssign::Full)
ArgValue = DAG.getNode(ISD::TRUNCATE, dl, VA.getValVT(), ArgValue);
InVals.push_back(ArgValue);
}
} else {
// Sanity check
assert(VA.isMemLoc());
// Load the argument to a virtual register
unsigned ObjSize = VA.getLocVT().getSizeInBits()/8;
if (ObjSize > 2) {
errs() << "LowerFormalArguments Unhandled argument type: "
<< EVT(VA.getLocVT()).getEVTString()
<< "\n";
}
// Create the frame index object for this incoming parameter...
int FI = MFI->CreateFixedObject(ObjSize, VA.getLocMemOffset(), true);
// Create the SelectionDAG nodes corresponding to a load
//from this parameter
SDValue FIN = DAG.getFrameIndex(FI, MVT::i16);
InVals.push_back(DAG.getLoad(VA.getLocVT(), dl, Chain, FIN,
MachinePointerInfo::getFixedStack(FI),
false, false, 0));
}
}
return Chain;
}
SDValue
MSP430TargetLowering::LowerReturn(SDValue Chain,
CallingConv::ID CallConv, bool isVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs,
const SmallVectorImpl<SDValue> &OutVals,
DebugLoc dl, SelectionDAG &DAG) const {
// CCValAssign - represent the assignment of the return value to a location
SmallVector<CCValAssign, 16> RVLocs;
// ISRs cannot return any value.
if (CallConv == CallingConv::MSP430_INTR && !Outs.empty()) {
report_fatal_error("ISRs cannot return any value");
return SDValue();
}
// CCState - Info about the registers and stack slot.
CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(),
getTargetMachine(), RVLocs, *DAG.getContext());
// Analize return values.
CCInfo.AnalyzeReturn(Outs, RetCC_MSP430);
// If this is the first return lowered for this function, add the regs to the
// liveout set for the function.
if (DAG.getMachineFunction().getRegInfo().liveout_empty()) {
for (unsigned i = 0; i != RVLocs.size(); ++i)
if (RVLocs[i].isRegLoc())
DAG.getMachineFunction().getRegInfo().addLiveOut(RVLocs[i].getLocReg());
}
SDValue Flag;
// Copy the result values into the output registers.
for (unsigned i = 0; i != RVLocs.size(); ++i) {
CCValAssign &VA = RVLocs[i];
assert(VA.isRegLoc() && "Can only return in registers!");
Chain = DAG.getCopyToReg(Chain, dl, VA.getLocReg(),
OutVals[i], Flag);
// Guarantee that all emitted copies are stuck together,
// avoiding something bad.
Flag = Chain.getValue(1);
}
unsigned Opc = (CallConv == CallingConv::MSP430_INTR ?
MSP430ISD::RETI_FLAG : MSP430ISD::RET_FLAG);
if (Flag.getNode())
return DAG.getNode(Opc, dl, MVT::Other, Chain, Flag);
// Return Void
return DAG.getNode(Opc, dl, MVT::Other, Chain);
}
/// LowerCCCCallTo - functions arguments are copied from virtual regs to
/// (physical regs)/(stack frame), CALLSEQ_START and CALLSEQ_END are emitted.
/// TODO: sret.
SDValue
MSP430TargetLowering::LowerCCCCallTo(SDValue Chain, SDValue Callee,
CallingConv::ID CallConv, bool isVarArg,
bool isTailCall,
const SmallVectorImpl<ISD::OutputArg>
&Outs,
const SmallVectorImpl<SDValue> &OutVals,
const SmallVectorImpl<ISD::InputArg> &Ins,
DebugLoc dl, SelectionDAG &DAG,
SmallVectorImpl<SDValue> &InVals) const {
// Analyze operands of the call, assigning locations to each operand.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(),
getTargetMachine(), ArgLocs, *DAG.getContext());
CCInfo.AnalyzeCallOperands(Outs, CC_MSP430);
// Get a count of how many bytes are to be pushed on the stack.
unsigned NumBytes = CCInfo.getNextStackOffset();
Chain = DAG.getCALLSEQ_START(Chain ,DAG.getConstant(NumBytes,
getPointerTy(), true));
SmallVector<std::pair<unsigned, SDValue>, 4> RegsToPass;
SmallVector<SDValue, 12> MemOpChains;
SDValue StackPtr;
// Walk the register/memloc assignments, inserting copies/loads.
for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
SDValue Arg = OutVals[i];
// Promote the value if needed.
switch (VA.getLocInfo()) {
default: llvm_unreachable("Unknown loc info!");
case CCValAssign::Full: break;
case CCValAssign::SExt:
Arg = DAG.getNode(ISD::SIGN_EXTEND, dl, VA.getLocVT(), Arg);
break;
case CCValAssign::ZExt:
Arg = DAG.getNode(ISD::ZERO_EXTEND, dl, VA.getLocVT(), Arg);
break;
case CCValAssign::AExt:
Arg = DAG.getNode(ISD::ANY_EXTEND, dl, VA.getLocVT(), Arg);
break;
}
// Arguments that can be passed on register must be kept at RegsToPass
// vector
if (VA.isRegLoc()) {
RegsToPass.push_back(std::make_pair(VA.getLocReg(), Arg));
} else {
assert(VA.isMemLoc());
if (StackPtr.getNode() == 0)
StackPtr = DAG.getCopyFromReg(Chain, dl, MSP430::SPW, getPointerTy());
SDValue PtrOff = DAG.getNode(ISD::ADD, dl, getPointerTy(),
StackPtr,
DAG.getIntPtrConstant(VA.getLocMemOffset()));
MemOpChains.push_back(DAG.getStore(Chain, dl, Arg, PtrOff,
MachinePointerInfo(),false, false, 0));
}
}
// Transform all store nodes into one single node because all store nodes are
// independent of each other.
if (!MemOpChains.empty())
Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
&MemOpChains[0], MemOpChains.size());
// Build a sequence of copy-to-reg nodes chained together with token chain and
// flag operands which copy the outgoing args into registers. The InFlag in
// necessary since all emitted instructions must be stuck together.
SDValue InFlag;
for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i) {
Chain = DAG.getCopyToReg(Chain, dl, RegsToPass[i].first,
RegsToPass[i].second, InFlag);
InFlag = Chain.getValue(1);
}
// If the callee is a GlobalAddress node (quite common, every direct call is)
// turn it into a TargetGlobalAddress node so that legalize doesn't hack it.
// Likewise ExternalSymbol -> TargetExternalSymbol.
if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee))
Callee = DAG.getTargetGlobalAddress(G->getGlobal(), dl, MVT::i16);
else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(Callee))
Callee = DAG.getTargetExternalSymbol(E->getSymbol(), MVT::i16);
// Returns a chain & a flag for retval copy to use.
SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
SmallVector<SDValue, 8> Ops;
Ops.push_back(Chain);
Ops.push_back(Callee);
// Add argument registers to the end of the list so that they are
// known live into the call.
for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i)
Ops.push_back(DAG.getRegister(RegsToPass[i].first,
RegsToPass[i].second.getValueType()));
if (InFlag.getNode())
Ops.push_back(InFlag);
Chain = DAG.getNode(MSP430ISD::CALL, dl, NodeTys, &Ops[0], Ops.size());
InFlag = Chain.getValue(1);
// Create the CALLSEQ_END node.
Chain = DAG.getCALLSEQ_END(Chain,
DAG.getConstant(NumBytes, getPointerTy(), true),
DAG.getConstant(0, getPointerTy(), true),
InFlag);
InFlag = Chain.getValue(1);
// Handle result values, copying them out of physregs into vregs that we
// return.
return LowerCallResult(Chain, InFlag, CallConv, isVarArg, Ins, dl,
DAG, InVals);
}
/// LowerCallResult - Lower the result values of a call into the
/// appropriate copies out of appropriate physical registers.
///
SDValue
MSP430TargetLowering::LowerCallResult(SDValue Chain, SDValue InFlag,
CallingConv::ID CallConv, bool isVarArg,
const SmallVectorImpl<ISD::InputArg> &Ins,
DebugLoc dl, SelectionDAG &DAG,
SmallVectorImpl<SDValue> &InVals) const {
// Assign locations to each value returned by this call.
SmallVector<CCValAssign, 16> RVLocs;
CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(),
getTargetMachine(), RVLocs, *DAG.getContext());
CCInfo.AnalyzeCallResult(Ins, RetCC_MSP430);
// Copy all of the result registers out of their specified physreg.
for (unsigned i = 0; i != RVLocs.size(); ++i) {
Chain = DAG.getCopyFromReg(Chain, dl, RVLocs[i].getLocReg(),
RVLocs[i].getValVT(), InFlag).getValue(1);
InFlag = Chain.getValue(2);
InVals.push_back(Chain.getValue(0));
}
return Chain;
}
SDValue MSP430TargetLowering::LowerShifts(SDValue Op,
SelectionDAG &DAG) const {
unsigned Opc = Op.getOpcode();
SDNode* N = Op.getNode();
EVT VT = Op.getValueType();
DebugLoc dl = N->getDebugLoc();
// Expand non-constant shifts to loops:
if (!isa<ConstantSDNode>(N->getOperand(1)))
switch (Opc) {
default:
assert(0 && "Invalid shift opcode!");
case ISD::SHL:
return DAG.getNode(MSP430ISD::SHL, dl,
VT, N->getOperand(0), N->getOperand(1));
case ISD::SRA:
return DAG.getNode(MSP430ISD::SRA, dl,
VT, N->getOperand(0), N->getOperand(1));
case ISD::SRL:
return DAG.getNode(MSP430ISD::SRL, dl,
VT, N->getOperand(0), N->getOperand(1));
}
uint64_t ShiftAmount = cast<ConstantSDNode>(N->getOperand(1))->getZExtValue();
// Expand the stuff into sequence of shifts.
// FIXME: for some shift amounts this might be done better!
// E.g.: foo >> (8 + N) => sxt(swpb(foo)) >> N
SDValue Victim = N->getOperand(0);
if (Opc == ISD::SRL && ShiftAmount) {
// Emit a special goodness here:
// srl A, 1 => clrc; rrc A
Victim = DAG.getNode(MSP430ISD::RRC, dl, VT, Victim);
ShiftAmount -= 1;
}
while (ShiftAmount--)
Victim = DAG.getNode((Opc == ISD::SHL ? MSP430ISD::RLA : MSP430ISD::RRA),
dl, VT, Victim);
return Victim;
}
SDValue MSP430TargetLowering::LowerGlobalAddress(SDValue Op,
SelectionDAG &DAG) const {
const GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
int64_t Offset = cast<GlobalAddressSDNode>(Op)->getOffset();
// Create the TargetGlobalAddress node, folding in the constant offset.
SDValue Result = DAG.getTargetGlobalAddress(GV, Op.getDebugLoc(),
getPointerTy(), Offset);
return DAG.getNode(MSP430ISD::Wrapper, Op.getDebugLoc(),
getPointerTy(), Result);
}
SDValue MSP430TargetLowering::LowerExternalSymbol(SDValue Op,
SelectionDAG &DAG) const {
DebugLoc dl = Op.getDebugLoc();
const char *Sym = cast<ExternalSymbolSDNode>(Op)->getSymbol();
SDValue Result = DAG.getTargetExternalSymbol(Sym, getPointerTy());
return DAG.getNode(MSP430ISD::Wrapper, dl, getPointerTy(), Result);;
}
SDValue MSP430TargetLowering::LowerBlockAddress(SDValue Op,
SelectionDAG &DAG) const {
DebugLoc dl = Op.getDebugLoc();
const BlockAddress *BA = cast<BlockAddressSDNode>(Op)->getBlockAddress();
SDValue Result = DAG.getBlockAddress(BA, getPointerTy(), /*isTarget=*/true);
return DAG.getNode(MSP430ISD::Wrapper, dl, getPointerTy(), Result);;
}
static SDValue EmitCMP(SDValue &LHS, SDValue &RHS, SDValue &TargetCC,
ISD::CondCode CC,
DebugLoc dl, SelectionDAG &DAG) {
// FIXME: Handle bittests someday
assert(!LHS.getValueType().isFloatingPoint() && "We don't handle FP yet");
// FIXME: Handle jump negative someday
MSP430CC::CondCodes TCC = MSP430CC::COND_INVALID;
switch (CC) {
default: llvm_unreachable("Invalid integer condition!");
case ISD::SETEQ:
TCC = MSP430CC::COND_E; // aka COND_Z
// Minor optimization: if LHS is a constant, swap operands, then the
// constant can be folded into comparison.
if (LHS.getOpcode() == ISD::Constant)
std::swap(LHS, RHS);
break;
case ISD::SETNE:
TCC = MSP430CC::COND_NE; // aka COND_NZ
// Minor optimization: if LHS is a constant, swap operands, then the
// constant can be folded into comparison.
if (LHS.getOpcode() == ISD::Constant)
std::swap(LHS, RHS);
break;
case ISD::SETULE:
std::swap(LHS, RHS); // FALLTHROUGH
case ISD::SETUGE:
// Turn lhs u>= rhs with lhs constant into rhs u< lhs+1, this allows us to
// fold constant into instruction.
if (const ConstantSDNode * C = dyn_cast<ConstantSDNode>(LHS)) {
LHS = RHS;
RHS = DAG.getConstant(C->getSExtValue() + 1, C->getValueType(0));
TCC = MSP430CC::COND_LO;
break;
}
TCC = MSP430CC::COND_HS; // aka COND_C
break;
case ISD::SETUGT:
std::swap(LHS, RHS); // FALLTHROUGH
case ISD::SETULT:
// Turn lhs u< rhs with lhs constant into rhs u>= lhs+1, this allows us to
// fold constant into instruction.
if (const ConstantSDNode * C = dyn_cast<ConstantSDNode>(LHS)) {
LHS = RHS;
RHS = DAG.getConstant(C->getSExtValue() + 1, C->getValueType(0));
TCC = MSP430CC::COND_HS;
break;
}
TCC = MSP430CC::COND_LO; // aka COND_NC
break;
case ISD::SETLE:
std::swap(LHS, RHS); // FALLTHROUGH
case ISD::SETGE:
// Turn lhs >= rhs with lhs constant into rhs < lhs+1, this allows us to
// fold constant into instruction.
if (const ConstantSDNode * C = dyn_cast<ConstantSDNode>(LHS)) {
LHS = RHS;
RHS = DAG.getConstant(C->getSExtValue() + 1, C->getValueType(0));
TCC = MSP430CC::COND_L;
break;
}
TCC = MSP430CC::COND_GE;
break;
case ISD::SETGT:
std::swap(LHS, RHS); // FALLTHROUGH
case ISD::SETLT:
// Turn lhs < rhs with lhs constant into rhs >= lhs+1, this allows us to
// fold constant into instruction.
if (const ConstantSDNode * C = dyn_cast<ConstantSDNode>(LHS)) {
LHS = RHS;
RHS = DAG.getConstant(C->getSExtValue() + 1, C->getValueType(0));
TCC = MSP430CC::COND_GE;
break;
}
TCC = MSP430CC::COND_L;
break;
}
TargetCC = DAG.getConstant(TCC, MVT::i8);
return DAG.getNode(MSP430ISD::CMP, dl, MVT::Glue, LHS, RHS);
}
SDValue MSP430TargetLowering::LowerBR_CC(SDValue Op, SelectionDAG &DAG) const {
SDValue Chain = Op.getOperand(0);
ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(1))->get();
SDValue LHS = Op.getOperand(2);
SDValue RHS = Op.getOperand(3);
SDValue Dest = Op.getOperand(4);
DebugLoc dl = Op.getDebugLoc();
SDValue TargetCC;
SDValue Flag = EmitCMP(LHS, RHS, TargetCC, CC, dl, DAG);
return DAG.getNode(MSP430ISD::BR_CC, dl, Op.getValueType(),
Chain, Dest, TargetCC, Flag);
}
SDValue MSP430TargetLowering::LowerSETCC(SDValue Op, SelectionDAG &DAG) const {
SDValue LHS = Op.getOperand(0);
SDValue RHS = Op.getOperand(1);
DebugLoc dl = Op.getDebugLoc();
// If we are doing an AND and testing against zero, then the CMP
// will not be generated. The AND (or BIT) will generate the condition codes,
// but they are different from CMP.
// FIXME: since we're doing a post-processing, use a pseudoinstr here, so
// lowering & isel wouldn't diverge.
bool andCC = false;
if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(RHS)) {
if (RHSC->isNullValue() && LHS.hasOneUse() &&
(LHS.getOpcode() == ISD::AND ||
(LHS.getOpcode() == ISD::TRUNCATE &&
LHS.getOperand(0).getOpcode() == ISD::AND))) {
andCC = true;
}
}
ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(2))->get();
SDValue TargetCC;
SDValue Flag = EmitCMP(LHS, RHS, TargetCC, CC, dl, DAG);
// Get the condition codes directly from the status register, if its easy.
// Otherwise a branch will be generated. Note that the AND and BIT
// instructions generate different flags than CMP, the carry bit can be used
// for NE/EQ.
bool Invert = false;
bool Shift = false;
bool Convert = true;
switch (cast<ConstantSDNode>(TargetCC)->getZExtValue()) {
default:
Convert = false;
break;
case MSP430CC::COND_HS:
// Res = SRW & 1, no processing is required
break;
case MSP430CC::COND_LO:
// Res = ~(SRW & 1)
Invert = true;
break;
case MSP430CC::COND_NE:
if (andCC) {
// C = ~Z, thus Res = SRW & 1, no processing is required
} else {
// Res = ~((SRW >> 1) & 1)
Shift = true;
Invert = true;
}
break;
case MSP430CC::COND_E:
Shift = true;
// C = ~Z for AND instruction, thus we can put Res = ~(SRW & 1), however,
// Res = (SRW >> 1) & 1 is 1 word shorter.
break;
}
EVT VT = Op.getValueType();
SDValue One = DAG.getConstant(1, VT);
if (Convert) {
SDValue SR = DAG.getCopyFromReg(DAG.getEntryNode(), dl, MSP430::SRW,
MVT::i16, Flag);
if (Shift)
// FIXME: somewhere this is turned into a SRL, lower it MSP specific?
SR = DAG.getNode(ISD::SRA, dl, MVT::i16, SR, One);
SR = DAG.getNode(ISD::AND, dl, MVT::i16, SR, One);
if (Invert)
SR = DAG.getNode(ISD::XOR, dl, MVT::i16, SR, One);
return SR;
} else {
SDValue Zero = DAG.getConstant(0, VT);
SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Glue);
SmallVector<SDValue, 4> Ops;
Ops.push_back(One);
Ops.push_back(Zero);
Ops.push_back(TargetCC);
Ops.push_back(Flag);
return DAG.getNode(MSP430ISD::SELECT_CC, dl, VTs, &Ops[0], Ops.size());
}
}
SDValue MSP430TargetLowering::LowerSELECT_CC(SDValue Op,
SelectionDAG &DAG) const {
SDValue LHS = Op.getOperand(0);
SDValue RHS = Op.getOperand(1);
SDValue TrueV = Op.getOperand(2);
SDValue FalseV = Op.getOperand(3);
ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(4))->get();
DebugLoc dl = Op.getDebugLoc();
SDValue TargetCC;
SDValue Flag = EmitCMP(LHS, RHS, TargetCC, CC, dl, DAG);
SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Glue);
SmallVector<SDValue, 4> Ops;
Ops.push_back(TrueV);
Ops.push_back(FalseV);
Ops.push_back(TargetCC);
Ops.push_back(Flag);
return DAG.getNode(MSP430ISD::SELECT_CC, dl, VTs, &Ops[0], Ops.size());
}
SDValue MSP430TargetLowering::LowerSIGN_EXTEND(SDValue Op,
SelectionDAG &DAG) const {
SDValue Val = Op.getOperand(0);
EVT VT = Op.getValueType();
DebugLoc dl = Op.getDebugLoc();
assert(VT == MVT::i16 && "Only support i16 for now!");
return DAG.getNode(ISD::SIGN_EXTEND_INREG, dl, VT,
DAG.getNode(ISD::ANY_EXTEND, dl, VT, Val),
DAG.getValueType(Val.getValueType()));
}
SDValue
MSP430TargetLowering::getReturnAddressFrameIndex(SelectionDAG &DAG) const {
MachineFunction &MF = DAG.getMachineFunction();
MSP430MachineFunctionInfo *FuncInfo = MF.getInfo<MSP430MachineFunctionInfo>();
int ReturnAddrIndex = FuncInfo->getRAIndex();
if (ReturnAddrIndex == 0) {
// Set up a frame object for the return address.
uint64_t SlotSize = TD->getPointerSize();
ReturnAddrIndex = MF.getFrameInfo()->CreateFixedObject(SlotSize, -SlotSize,
true);
FuncInfo->setRAIndex(ReturnAddrIndex);
}
return DAG.getFrameIndex(ReturnAddrIndex, getPointerTy());
}
SDValue MSP430TargetLowering::LowerRETURNADDR(SDValue Op,
SelectionDAG &DAG) const {
MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
MFI->setReturnAddressIsTaken(true);
unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
DebugLoc dl = Op.getDebugLoc();
if (Depth > 0) {
SDValue FrameAddr = LowerFRAMEADDR(Op, DAG);
SDValue Offset =
DAG.getConstant(TD->getPointerSize(), MVT::i16);
return DAG.getLoad(getPointerTy(), dl, DAG.getEntryNode(),
DAG.getNode(ISD::ADD, dl, getPointerTy(),
FrameAddr, Offset),
MachinePointerInfo(), false, false, 0);
}
// Just load the return address.
SDValue RetAddrFI = getReturnAddressFrameIndex(DAG);
return DAG.getLoad(getPointerTy(), dl, DAG.getEntryNode(),
RetAddrFI, MachinePointerInfo(), false, false, 0);
}
SDValue MSP430TargetLowering::LowerFRAMEADDR(SDValue Op,
SelectionDAG &DAG) const {
MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
MFI->setFrameAddressIsTaken(true);
EVT VT = Op.getValueType();
DebugLoc dl = Op.getDebugLoc(); // FIXME probably not meaningful
unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
SDValue FrameAddr = DAG.getCopyFromReg(DAG.getEntryNode(), dl,
MSP430::FPW, VT);
while (Depth--)
FrameAddr = DAG.getLoad(VT, dl, DAG.getEntryNode(), FrameAddr,
MachinePointerInfo(),
false, false, 0);
return FrameAddr;
}
/// getPostIndexedAddressParts - returns true by value, base pointer and
/// offset pointer and addressing mode by reference if this node can be
/// combined with a load / store to form a post-indexed load / store.
bool MSP430TargetLowering::getPostIndexedAddressParts(SDNode *N, SDNode *Op,
SDValue &Base,
SDValue &Offset,
ISD::MemIndexedMode &AM,
SelectionDAG &DAG) const {
LoadSDNode *LD = cast<LoadSDNode>(N);
if (LD->getExtensionType() != ISD::NON_EXTLOAD)
return false;
EVT VT = LD->getMemoryVT();
if (VT != MVT::i8 && VT != MVT::i16)
return false;
if (Op->getOpcode() != ISD::ADD)
return false;
if (ConstantSDNode *RHS = dyn_cast<ConstantSDNode>(Op->getOperand(1))) {
uint64_t RHSC = RHS->getZExtValue();
if ((VT == MVT::i16 && RHSC != 2) ||
(VT == MVT::i8 && RHSC != 1))
return false;
Base = Op->getOperand(0);
Offset = DAG.getConstant(RHSC, VT);
AM = ISD::POST_INC;
return true;
}
return false;
}
const char *MSP430TargetLowering::getTargetNodeName(unsigned Opcode) const {
switch (Opcode) {
default: return NULL;
case MSP430ISD::RET_FLAG: return "MSP430ISD::RET_FLAG";
case MSP430ISD::RETI_FLAG: return "MSP430ISD::RETI_FLAG";
case MSP430ISD::RRA: return "MSP430ISD::RRA";
case MSP430ISD::RLA: return "MSP430ISD::RLA";
case MSP430ISD::RRC: return "MSP430ISD::RRC";
case MSP430ISD::CALL: return "MSP430ISD::CALL";
case MSP430ISD::Wrapper: return "MSP430ISD::Wrapper";
case MSP430ISD::BR_CC: return "MSP430ISD::BR_CC";
case MSP430ISD::CMP: return "MSP430ISD::CMP";
case MSP430ISD::SELECT_CC: return "MSP430ISD::SELECT_CC";
case MSP430ISD::SHL: return "MSP430ISD::SHL";
case MSP430ISD::SRA: return "MSP430ISD::SRA";
}
}
bool MSP430TargetLowering::isTruncateFree(Type *Ty1,
Type *Ty2) const {
if (!Ty1->isIntegerTy() || !Ty2->isIntegerTy())
return false;
return (Ty1->getPrimitiveSizeInBits() > Ty2->getPrimitiveSizeInBits());
}
bool MSP430TargetLowering::isTruncateFree(EVT VT1, EVT VT2) const {
if (!VT1.isInteger() || !VT2.isInteger())
return false;
return (VT1.getSizeInBits() > VT2.getSizeInBits());
}
bool MSP430TargetLowering::isZExtFree(Type *Ty1, Type *Ty2) const {
// MSP430 implicitly zero-extends 8-bit results in 16-bit registers.
return 0 && Ty1->isIntegerTy(8) && Ty2->isIntegerTy(16);
}
bool MSP430TargetLowering::isZExtFree(EVT VT1, EVT VT2) const {
// MSP430 implicitly zero-extends 8-bit results in 16-bit registers.
return 0 && VT1 == MVT::i8 && VT2 == MVT::i16;
}
//===----------------------------------------------------------------------===//
// Other Lowering Code
//===----------------------------------------------------------------------===//
MachineBasicBlock*
MSP430TargetLowering::EmitShiftInstr(MachineInstr *MI,
MachineBasicBlock *BB) const {
MachineFunction *F = BB->getParent();
MachineRegisterInfo &RI = F->getRegInfo();
DebugLoc dl = MI->getDebugLoc();
const TargetInstrInfo &TII = *getTargetMachine().getInstrInfo();
unsigned Opc;
const TargetRegisterClass * RC;
switch (MI->getOpcode()) {
default:
assert(0 && "Invalid shift opcode!");
case MSP430::Shl8:
Opc = MSP430::SHL8r1;
RC = MSP430::GR8RegisterClass;
break;
case MSP430::Shl16:
Opc = MSP430::SHL16r1;
RC = MSP430::GR16RegisterClass;
break;
case MSP430::Sra8:
Opc = MSP430::SAR8r1;
RC = MSP430::GR8RegisterClass;
break;
case MSP430::Sra16:
Opc = MSP430::SAR16r1;
RC = MSP430::GR16RegisterClass;
break;
case MSP430::Srl8:
Opc = MSP430::SAR8r1c;
RC = MSP430::GR8RegisterClass;
break;
case MSP430::Srl16:
Opc = MSP430::SAR16r1c;
RC = MSP430::GR16RegisterClass;
break;
}
const BasicBlock *LLVM_BB = BB->getBasicBlock();
MachineFunction::iterator I = BB;
++I;
// Create loop block
MachineBasicBlock *LoopBB = F->CreateMachineBasicBlock(LLVM_BB);
MachineBasicBlock *RemBB = F->CreateMachineBasicBlock(LLVM_BB);
F->insert(I, LoopBB);
F->insert(I, RemBB);
// Update machine-CFG edges by transferring all successors of the current
// block to the block containing instructions after shift.
RemBB->splice(RemBB->begin(), BB,
llvm::next(MachineBasicBlock::iterator(MI)),
BB->end());
RemBB->transferSuccessorsAndUpdatePHIs(BB);
// Add adges BB => LoopBB => RemBB, BB => RemBB, LoopBB => LoopBB
BB->addSuccessor(LoopBB);
BB->addSuccessor(RemBB);
LoopBB->addSuccessor(RemBB);
LoopBB->addSuccessor(LoopBB);
unsigned ShiftAmtReg = RI.createVirtualRegister(MSP430::GR8RegisterClass);
unsigned ShiftAmtReg2 = RI.createVirtualRegister(MSP430::GR8RegisterClass);
unsigned ShiftReg = RI.createVirtualRegister(RC);
unsigned ShiftReg2 = RI.createVirtualRegister(RC);
unsigned ShiftAmtSrcReg = MI->getOperand(2).getReg();
unsigned SrcReg = MI->getOperand(1).getReg();
unsigned DstReg = MI->getOperand(0).getReg();
// BB:
// cmp 0, N
// je RemBB
BuildMI(BB, dl, TII.get(MSP430::CMP8ri))
.addReg(ShiftAmtSrcReg).addImm(0);
BuildMI(BB, dl, TII.get(MSP430::JCC))
.addMBB(RemBB)
.addImm(MSP430CC::COND_E);
// LoopBB:
// ShiftReg = phi [%SrcReg, BB], [%ShiftReg2, LoopBB]
// ShiftAmt = phi [%N, BB], [%ShiftAmt2, LoopBB]
// ShiftReg2 = shift ShiftReg
// ShiftAmt2 = ShiftAmt - 1;
BuildMI(LoopBB, dl, TII.get(MSP430::PHI), ShiftReg)
.addReg(SrcReg).addMBB(BB)
.addReg(ShiftReg2).addMBB(LoopBB);
BuildMI(LoopBB, dl, TII.get(MSP430::PHI), ShiftAmtReg)
.addReg(ShiftAmtSrcReg).addMBB(BB)
.addReg(ShiftAmtReg2).addMBB(LoopBB);
BuildMI(LoopBB, dl, TII.get(Opc), ShiftReg2)
.addReg(ShiftReg);
BuildMI(LoopBB, dl, TII.get(MSP430::SUB8ri), ShiftAmtReg2)
.addReg(ShiftAmtReg).addImm(1);
BuildMI(LoopBB, dl, TII.get(MSP430::JCC))
.addMBB(LoopBB)
.addImm(MSP430CC::COND_NE);
// RemBB:
// DestReg = phi [%SrcReg, BB], [%ShiftReg, LoopBB]
BuildMI(*RemBB, RemBB->begin(), dl, TII.get(MSP430::PHI), DstReg)
.addReg(SrcReg).addMBB(BB)
.addReg(ShiftReg2).addMBB(LoopBB);
MI->eraseFromParent(); // The pseudo instruction is gone now.
return RemBB;
}
MachineBasicBlock*
MSP430TargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
MachineBasicBlock *BB) const {
unsigned Opc = MI->getOpcode();
if (Opc == MSP430::Shl8 || Opc == MSP430::Shl16 ||
Opc == MSP430::Sra8 || Opc == MSP430::Sra16 ||
Opc == MSP430::Srl8 || Opc == MSP430::Srl16)
return EmitShiftInstr(MI, BB);
const TargetInstrInfo &TII = *getTargetMachine().getInstrInfo();
DebugLoc dl = MI->getDebugLoc();
assert((Opc == MSP430::Select16 || Opc == MSP430::Select8) &&
"Unexpected instr type to insert");
// To "insert" a SELECT instruction, we actually have to insert the diamond
// control-flow pattern. The incoming instruction knows the destination vreg
// to set, the condition code register to branch on, the true/false values to
// select between, and a branch opcode to use.
const BasicBlock *LLVM_BB = BB->getBasicBlock();
MachineFunction::iterator I = BB;
++I;
// thisMBB:
// ...
// TrueVal = ...
// cmpTY ccX, r1, r2
// jCC copy1MBB
// fallthrough --> copy0MBB
MachineBasicBlock *thisMBB = BB;
MachineFunction *F = BB->getParent();
MachineBasicBlock *copy0MBB = F->CreateMachineBasicBlock(LLVM_BB);
MachineBasicBlock *copy1MBB = F->CreateMachineBasicBlock(LLVM_BB);
F->insert(I, copy0MBB);
F->insert(I, copy1MBB);
// Update machine-CFG edges by transferring all successors of the current
// block to the new block which will contain the Phi node for the select.
copy1MBB->splice(copy1MBB->begin(), BB,
llvm::next(MachineBasicBlock::iterator(MI)),
BB->end());
copy1MBB->transferSuccessorsAndUpdatePHIs(BB);
// Next, add the true and fallthrough blocks as its successors.
BB->addSuccessor(copy0MBB);
BB->addSuccessor(copy1MBB);
BuildMI(BB, dl, TII.get(MSP430::JCC))
.addMBB(copy1MBB)
.addImm(MI->getOperand(3).getImm());
// copy0MBB:
// %FalseValue = ...
// # fallthrough to copy1MBB
BB = copy0MBB;
// Update machine-CFG edges
BB->addSuccessor(copy1MBB);
// copy1MBB:
// %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, thisMBB ]
// ...
BB = copy1MBB;
BuildMI(*BB, BB->begin(), dl, TII.get(MSP430::PHI),
MI->getOperand(0).getReg())
.addReg(MI->getOperand(2).getReg()).addMBB(copy0MBB)
.addReg(MI->getOperand(1).getReg()).addMBB(thisMBB);
MI->eraseFromParent(); // The pseudo instruction is gone now.
return BB;
}