llvm-6502/lib/Target/IA64/IA64ISelDAGToDAG.cpp

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//===---- IA64ISelDAGToDAG.cpp - IA64 pattern matching inst selector ------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Duraid Madina and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a pattern matching instruction selector for IA64,
// converting a legalized dag to an IA64 dag.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "ia64-codegen"
#include "IA64.h"
#include "IA64TargetMachine.h"
#include "IA64ISelLowering.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Constants.h"
#include "llvm/GlobalValue.h"
#include "llvm/Intrinsics.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include <queue>
#include <set>
using namespace llvm;
namespace {
//===--------------------------------------------------------------------===//
/// IA64DAGToDAGISel - IA64 specific code to select IA64 machine
/// instructions for SelectionDAG operations.
///
class IA64DAGToDAGISel : public SelectionDAGISel {
IA64TargetLowering IA64Lowering;
unsigned GlobalBaseReg;
public:
IA64DAGToDAGISel(IA64TargetMachine &TM)
: SelectionDAGISel(IA64Lowering), IA64Lowering(*TM.getTargetLowering()) {}
virtual bool runOnFunction(Function &Fn) {
// Make sure we re-emit a set of the global base reg if necessary
GlobalBaseReg = 0;
return SelectionDAGISel::runOnFunction(Fn);
}
/// getI64Imm - Return a target constant with the specified value, of type
/// i64.
inline SDOperand getI64Imm(uint64_t Imm) {
return CurDAG->getTargetConstant(Imm, MVT::i64);
}
/// getGlobalBaseReg - insert code into the entry mbb to materialize the PIC
/// base register. Return the virtual register that holds this value.
// SDOperand getGlobalBaseReg(); TODO: hmm
// Select - Convert the specified operand from a target-independent to a
// target-specific node if it hasn't already been changed.
SDNode *Select(SDOperand N);
SDNode *SelectIntImmediateExpr(SDOperand LHS, SDOperand RHS,
unsigned OCHi, unsigned OCLo,
bool IsArithmetic = false,
bool Negate = false);
SDNode *SelectBitfieldInsert(SDNode *N);
/// SelectCC - Select a comparison of the specified values with the
/// specified condition code, returning the CR# of the expression.
SDOperand SelectCC(SDOperand LHS, SDOperand RHS, ISD::CondCode CC);
/// SelectAddr - Given the specified address, return the two operands for a
/// load/store instruction, and return true if it should be an indexed [r+r]
/// operation.
bool SelectAddr(SDOperand Addr, SDOperand &Op1, SDOperand &Op2);
/// InstructionSelectBasicBlock - This callback is invoked by
/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
virtual void InstructionSelectBasicBlock(SelectionDAG &DAG);
virtual const char *getPassName() const {
return "IA64 (Itanium) DAG->DAG Instruction Selector";
}
// Include the pieces autogenerated from the target description.
#include "IA64GenDAGISel.inc"
private:
SDNode *SelectDIV(SDOperand Op);
};
}
/// InstructionSelectBasicBlock - This callback is invoked by
/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
void IA64DAGToDAGISel::InstructionSelectBasicBlock(SelectionDAG &DAG) {
DEBUG(BB->dump());
// Select target instructions for the DAG.
DAG.setRoot(SelectRoot(DAG.getRoot()));
DAG.RemoveDeadNodes();
// Emit machine code to BB.
ScheduleAndEmitDAG(DAG);
}
SDNode *IA64DAGToDAGISel::SelectDIV(SDOperand Op) {
SDNode *N = Op.Val;
SDOperand Chain = N->getOperand(0);
SDOperand Tmp1 = N->getOperand(0);
SDOperand Tmp2 = N->getOperand(1);
AddToISelQueue(Chain);
AddToISelQueue(Tmp1);
AddToISelQueue(Tmp2);
bool isFP=false;
if(MVT::isFloatingPoint(Tmp1.getValueType()))
isFP=true;
bool isModulus=false; // is it a division or a modulus?
bool isSigned=false;
switch(N->getOpcode()) {
case ISD::FDIV:
case ISD::SDIV: isModulus=false; isSigned=true; break;
case ISD::UDIV: isModulus=false; isSigned=false; break;
case ISD::FREM:
case ISD::SREM: isModulus=true; isSigned=true; break;
case ISD::UREM: isModulus=true; isSigned=false; break;
}
// TODO: check for integer divides by powers of 2 (or other simple patterns?)
SDOperand TmpPR, TmpPR2;
SDOperand TmpF1, TmpF2, TmpF3, TmpF4, TmpF5, TmpF6, TmpF7, TmpF8;
SDOperand TmpF9, TmpF10,TmpF11,TmpF12,TmpF13,TmpF14,TmpF15;
SDNode *Result;
// we'll need copies of F0 and F1
SDOperand F0 = CurDAG->getRegister(IA64::F0, MVT::f64);
SDOperand F1 = CurDAG->getRegister(IA64::F1, MVT::f64);
// OK, emit some code:
if(!isFP) {
// first, load the inputs into FP regs.
TmpF1 =
SDOperand(CurDAG->getTargetNode(IA64::SETFSIG, MVT::f64, Tmp1), 0);
Chain = TmpF1.getValue(1);
TmpF2 =
SDOperand(CurDAG->getTargetNode(IA64::SETFSIG, MVT::f64, Tmp2), 0);
Chain = TmpF2.getValue(1);
// next, convert the inputs to FP
if(isSigned) {
TmpF3 =
SDOperand(CurDAG->getTargetNode(IA64::FCVTXF, MVT::f64, TmpF1), 0);
Chain = TmpF3.getValue(1);
TmpF4 =
SDOperand(CurDAG->getTargetNode(IA64::FCVTXF, MVT::f64, TmpF2), 0);
Chain = TmpF4.getValue(1);
} else { // is unsigned
TmpF3 =
SDOperand(CurDAG->getTargetNode(IA64::FCVTXUFS1, MVT::f64, TmpF1), 0);
Chain = TmpF3.getValue(1);
TmpF4 =
SDOperand(CurDAG->getTargetNode(IA64::FCVTXUFS1, MVT::f64, TmpF2), 0);
Chain = TmpF4.getValue(1);
}
} else { // this is an FP divide/remainder, so we 'leak' some temp
// regs and assign TmpF3=Tmp1, TmpF4=Tmp2
TmpF3=Tmp1;
TmpF4=Tmp2;
}
// we start by computing an approximate reciprocal (good to 9 bits?)
// note, this instruction writes _both_ TmpF5 (answer) and TmpPR (predicate)
if(isFP)
TmpF5 = SDOperand(CurDAG->getTargetNode(IA64::FRCPAS0, MVT::f64, MVT::i1,
TmpF3, TmpF4), 0);
else
TmpF5 = SDOperand(CurDAG->getTargetNode(IA64::FRCPAS1, MVT::f64, MVT::i1,
TmpF3, TmpF4), 0);
TmpPR = TmpF5.getValue(1);
Chain = TmpF5.getValue(2);
SDOperand minusB;
if(isModulus) { // for remainders, it'll be handy to have
// copies of -input_b
minusB = SDOperand(CurDAG->getTargetNode(IA64::SUB, MVT::i64,
CurDAG->getRegister(IA64::r0, MVT::i64), Tmp2), 0);
Chain = minusB.getValue(1);
}
SDOperand TmpE0, TmpY1, TmpE1, TmpY2;
SDOperand OpsE0[] = { TmpF4, TmpF5, F1, TmpPR };
TmpE0 = SDOperand(CurDAG->getTargetNode(IA64::CFNMAS1, MVT::f64,
OpsE0, 4), 0);
Chain = TmpE0.getValue(1);
SDOperand OpsY1[] = { TmpF5, TmpE0, TmpF5, TmpPR };
TmpY1 = SDOperand(CurDAG->getTargetNode(IA64::CFMAS1, MVT::f64,
OpsY1, 4), 0);
Chain = TmpY1.getValue(1);
SDOperand OpsE1[] = { TmpE0, TmpE0, F0, TmpPR };
TmpE1 = SDOperand(CurDAG->getTargetNode(IA64::CFMAS1, MVT::f64,
OpsE1, 4), 0);
Chain = TmpE1.getValue(1);
SDOperand OpsY2[] = { TmpY1, TmpE1, TmpY1, TmpPR };
TmpY2 = SDOperand(CurDAG->getTargetNode(IA64::CFMAS1, MVT::f64,
OpsY2, 4), 0);
Chain = TmpY2.getValue(1);
if(isFP) { // if this is an FP divide, we finish up here and exit early
if(isModulus)
assert(0 && "Sorry, try another FORTRAN compiler.");
SDOperand TmpE2, TmpY3, TmpQ0, TmpR0;
SDOperand OpsE2[] = { TmpE1, TmpE1, F0, TmpPR };
TmpE2 = SDOperand(CurDAG->getTargetNode(IA64::CFMAS1, MVT::f64,
OpsE2, 4), 0);
Chain = TmpE2.getValue(1);
SDOperand OpsY3[] = { TmpY2, TmpE2, TmpY2, TmpPR };
TmpY3 = SDOperand(CurDAG->getTargetNode(IA64::CFMAS1, MVT::f64,
OpsY3, 4), 0);
Chain = TmpY3.getValue(1);
SDOperand OpsQ0[] = { Tmp1, TmpY3, F0, TmpPR };
TmpQ0 =
SDOperand(CurDAG->getTargetNode(IA64::CFMADS1, MVT::f64, // double prec!
OpsQ0, 4), 0);
Chain = TmpQ0.getValue(1);
SDOperand OpsR0[] = { Tmp2, TmpQ0, Tmp1, TmpPR };
TmpR0 =
SDOperand(CurDAG->getTargetNode(IA64::CFNMADS1, MVT::f64, // double prec!
OpsR0, 4), 0);
Chain = TmpR0.getValue(1);
// we want Result to have the same target register as the frcpa, so
// we two-address hack it. See the comment "for this to work..." on
// page 48 of Intel application note #245415
SDOperand Ops[] = { TmpF5, TmpY3, TmpR0, TmpQ0, TmpPR };
Result = CurDAG->getTargetNode(IA64::TCFMADS0, MVT::f64, // d.p. s0 rndg!
Ops, 5);
Chain = SDOperand(Result, 1);
return Result; // XXX: early exit!
} else { // this is *not* an FP divide, so there's a bit left to do:
SDOperand TmpQ2, TmpR2, TmpQ3, TmpQ;
SDOperand OpsQ2[] = { TmpF3, TmpY2, F0, TmpPR };
TmpQ2 = SDOperand(CurDAG->getTargetNode(IA64::CFMAS1, MVT::f64,
OpsQ2, 4), 0);
Chain = TmpQ2.getValue(1);
SDOperand OpsR2[] = { TmpF4, TmpQ2, TmpF3, TmpPR };
TmpR2 = SDOperand(CurDAG->getTargetNode(IA64::CFNMAS1, MVT::f64,
OpsR2, 4), 0);
Chain = TmpR2.getValue(1);
// we want TmpQ3 to have the same target register as the frcpa? maybe we
// should two-address hack it. See the comment "for this to work..." on page
// 48 of Intel application note #245415
SDOperand OpsQ3[] = { TmpF5, TmpR2, TmpY2, TmpQ2, TmpPR };
TmpQ3 = SDOperand(CurDAG->getTargetNode(IA64::TCFMAS1, MVT::f64,
OpsQ3, 5), 0);
Chain = TmpQ3.getValue(1);
// STORY: without these two-address instructions (TCFMAS1 and TCFMADS0)
// the FPSWA won't be able to help out in the case of large/tiny
// arguments. Other fun bugs may also appear, e.g. 0/x = x, not 0.
if(isSigned)
TmpQ = SDOperand(CurDAG->getTargetNode(IA64::FCVTFXTRUNCS1,
MVT::f64, TmpQ3), 0);
else
TmpQ = SDOperand(CurDAG->getTargetNode(IA64::FCVTFXUTRUNCS1,
MVT::f64, TmpQ3), 0);
Chain = TmpQ.getValue(1);
if(isModulus) {
SDOperand FPminusB =
SDOperand(CurDAG->getTargetNode(IA64::SETFSIG, MVT::f64, minusB), 0);
Chain = FPminusB.getValue(1);
SDOperand Remainder =
SDOperand(CurDAG->getTargetNode(IA64::XMAL, MVT::f64,
TmpQ, FPminusB, TmpF1), 0);
Chain = Remainder.getValue(1);
Result = CurDAG->getTargetNode(IA64::GETFSIG, MVT::i64, Remainder);
Chain = SDOperand(Result, 1);
} else { // just an integer divide
Result = CurDAG->getTargetNode(IA64::GETFSIG, MVT::i64, TmpQ);
Chain = SDOperand(Result, 1);
}
return Result;
} // wasn't an FP divide
}
// Select - Convert the specified operand from a target-independent to a
// target-specific node if it hasn't already been changed.
SDNode *IA64DAGToDAGISel::Select(SDOperand Op) {
SDNode *N = Op.Val;
if (N->getOpcode() >= ISD::BUILTIN_OP_END &&
N->getOpcode() < IA64ISD::FIRST_NUMBER)
return NULL; // Already selected.
switch (N->getOpcode()) {
default: break;
case IA64ISD::BRCALL: { // XXX: this is also a hack!
SDOperand Chain = N->getOperand(0);
SDOperand InFlag; // Null incoming flag value.
AddToISelQueue(Chain);
if(N->getNumOperands()==3) { // we have an incoming chain, callee and flag
InFlag = N->getOperand(2);
AddToISelQueue(InFlag);
}
unsigned CallOpcode;
SDOperand CallOperand;
// if we can call directly, do so
if (GlobalAddressSDNode *GASD =
dyn_cast<GlobalAddressSDNode>(N->getOperand(1))) {
CallOpcode = IA64::BRCALL_IPREL_GA;
CallOperand = CurDAG->getTargetGlobalAddress(GASD->getGlobal(), MVT::i64);
} else if (isa<ExternalSymbolSDNode>(N->getOperand(1))) {
// FIXME: we currently NEED this case for correctness, to avoid
// "non-pic code with imm reloc.n against dynamic symbol" errors
CallOpcode = IA64::BRCALL_IPREL_ES;
CallOperand = N->getOperand(1);
} else {
// otherwise we need to load the function descriptor,
// load the branch target (function)'s entry point and GP,
// branch (call) then restore the GP
SDOperand FnDescriptor = N->getOperand(1);
AddToISelQueue(FnDescriptor);
// load the branch target's entry point [mem] and
// GP value [mem+8]
SDOperand targetEntryPoint=
SDOperand(CurDAG->getTargetNode(IA64::LD8, MVT::i64, FnDescriptor), 0);
Chain = targetEntryPoint.getValue(1);
SDOperand targetGPAddr=
SDOperand(CurDAG->getTargetNode(IA64::ADDS, MVT::i64,
FnDescriptor,
CurDAG->getConstant(8, MVT::i64)), 0);
Chain = targetGPAddr.getValue(1);
SDOperand targetGP =
SDOperand(CurDAG->getTargetNode(IA64::LD8, MVT::i64, targetGPAddr), 0);
Chain = targetGP.getValue(1);
Chain = CurDAG->getCopyToReg(Chain, IA64::r1, targetGP, InFlag);
InFlag = Chain.getValue(1);
Chain = CurDAG->getCopyToReg(Chain, IA64::B6, targetEntryPoint, InFlag); // FLAG these?
InFlag = Chain.getValue(1);
CallOperand = CurDAG->getRegister(IA64::B6, MVT::i64);
CallOpcode = IA64::BRCALL_INDIRECT;
}
// Finally, once everything is setup, emit the call itself
if(InFlag.Val)
Chain = SDOperand(CurDAG->getTargetNode(CallOpcode, MVT::Other, MVT::Flag,
CallOperand, InFlag), 0);
else // there might be no arguments
Chain = SDOperand(CurDAG->getTargetNode(CallOpcode, MVT::Other, MVT::Flag,
CallOperand, Chain), 0);
InFlag = Chain.getValue(1);
std::vector<SDOperand> CallResults;
CallResults.push_back(Chain);
CallResults.push_back(InFlag);
for (unsigned i = 0, e = CallResults.size(); i != e; ++i)
ReplaceUses(Op.getValue(i), CallResults[i]);
return NULL;
}
case IA64ISD::GETFD: {
SDOperand Input = N->getOperand(0);
AddToISelQueue(Input);
return CurDAG->getTargetNode(IA64::GETFD, MVT::i64, Input);
}
case ISD::FDIV:
case ISD::SDIV:
case ISD::UDIV:
case ISD::SREM:
case ISD::UREM:
return SelectDIV(Op);
case ISD::TargetConstantFP: {
SDOperand Chain = CurDAG->getEntryNode(); // this is a constant, so..
SDOperand V;
if (cast<ConstantFPSDNode>(N)->isExactlyValue(+0.0)) {
V = CurDAG->getCopyFromReg(Chain, IA64::F0, MVT::f64);
} else if (cast<ConstantFPSDNode>(N)->isExactlyValue(+1.0)) {
V = CurDAG->getCopyFromReg(Chain, IA64::F1, MVT::f64);
} else
assert(0 && "Unexpected FP constant!");
ReplaceUses(SDOperand(N, 0), V);
return 0;
}
case ISD::FrameIndex: { // TODO: reduce creepyness
int FI = cast<FrameIndexSDNode>(N)->getIndex();
if (N->hasOneUse())
return CurDAG->SelectNodeTo(N, IA64::MOV, MVT::i64,
CurDAG->getTargetFrameIndex(FI, MVT::i64));
else
return CurDAG->getTargetNode(IA64::MOV, MVT::i64,
CurDAG->getTargetFrameIndex(FI, MVT::i64));
}
case ISD::ConstantPool: { // TODO: nuke the constant pool
// (ia64 doesn't need one)
ConstantPoolSDNode *CP = cast<ConstantPoolSDNode>(N);
Constant *C = CP->getConstVal();
SDOperand CPI = CurDAG->getTargetConstantPool(C, MVT::i64,
CP->getAlignment());
return CurDAG->getTargetNode(IA64::ADDL_GA, MVT::i64, // ?
CurDAG->getRegister(IA64::r1, MVT::i64), CPI);
}
case ISD::GlobalAddress: {
GlobalValue *GV = cast<GlobalAddressSDNode>(N)->getGlobal();
SDOperand GA = CurDAG->getTargetGlobalAddress(GV, MVT::i64);
SDOperand Tmp =
SDOperand(CurDAG->getTargetNode(IA64::ADDL_GA, MVT::i64,
CurDAG->getRegister(IA64::r1,
MVT::i64), GA), 0);
return CurDAG->getTargetNode(IA64::LD8, MVT::i64, Tmp);
}
/* XXX
case ISD::ExternalSymbol: {
SDOperand EA = CurDAG->getTargetExternalSymbol(
cast<ExternalSymbolSDNode>(N)->getSymbol(),
MVT::i64);
SDOperand Tmp = CurDAG->getTargetNode(IA64::ADDL_EA, MVT::i64,
CurDAG->getRegister(IA64::r1,
MVT::i64),
EA);
return CurDAG->getTargetNode(IA64::LD8, MVT::i64, Tmp);
}
*/
case ISD::LOAD: { // FIXME: load -1, not 1, for bools?
LoadSDNode *LD = cast<LoadSDNode>(N);
SDOperand Chain = LD->getChain();
SDOperand Address = LD->getBasePtr();
AddToISelQueue(Chain);
AddToISelQueue(Address);
MVT::ValueType TypeBeingLoaded = LD->getLoadedVT();
unsigned Opc;
switch (TypeBeingLoaded) {
default:
#ifndef NDEBUG
N->dump();
#endif
assert(0 && "Cannot load this type!");
case MVT::i1: { // this is a bool
Opc = IA64::LD1; // first we load a byte, then compare for != 0
if(N->getValueType(0) == MVT::i1) { // XXX: early exit!
return CurDAG->SelectNodeTo(N, IA64::CMPNE, MVT::i1, MVT::Other,
SDOperand(CurDAG->getTargetNode(Opc, MVT::i64, Address), 0),
CurDAG->getRegister(IA64::r0, MVT::i64),
Chain);
}
/* otherwise, we want to load a bool into something bigger: LD1
will do that for us, so we just fall through */
}
case MVT::i8: Opc = IA64::LD1; break;
case MVT::i16: Opc = IA64::LD2; break;
case MVT::i32: Opc = IA64::LD4; break;
case MVT::i64: Opc = IA64::LD8; break;
case MVT::f32: Opc = IA64::LDF4; break;
case MVT::f64: Opc = IA64::LDF8; break;
}
// TODO: comment this
return CurDAG->SelectNodeTo(N, Opc, N->getValueType(0), MVT::Other,
Address, Chain);
}
case ISD::STORE: {
StoreSDNode *ST = cast<StoreSDNode>(N);
SDOperand Address = ST->getBasePtr();
SDOperand Chain = ST->getChain();
AddToISelQueue(Address);
AddToISelQueue(Chain);
unsigned Opc;
if (ISD::isNON_TRUNCStore(N)) {
switch (N->getOperand(1).getValueType()) {
default: assert(0 && "unknown type in store");
case MVT::i1: { // this is a bool
Opc = IA64::ST1; // we store either 0 or 1 as a byte
// first load zero!
SDOperand Initial = CurDAG->getCopyFromReg(Chain, IA64::r0, MVT::i64);
Chain = Initial.getValue(1);
// then load 1 into the same reg iff the predicate to store is 1
SDOperand Tmp = ST->getValue();
AddToISelQueue(Tmp);
Tmp =
SDOperand(CurDAG->getTargetNode(IA64::TPCADDS, MVT::i64, Initial,
CurDAG->getTargetConstant(1, MVT::i64),
Tmp), 0);
return CurDAG->SelectNodeTo(N, Opc, MVT::Other, Address, Tmp, Chain);
}
case MVT::i64: Opc = IA64::ST8; break;
case MVT::f64: Opc = IA64::STF8; break;
}
} else { // Truncating store
switch(ST->getStoredVT()) {
default: assert(0 && "unknown type in truncstore");
case MVT::i8: Opc = IA64::ST1; break;
case MVT::i16: Opc = IA64::ST2; break;
case MVT::i32: Opc = IA64::ST4; break;
case MVT::f32: Opc = IA64::STF4; break;
}
}
SDOperand N1 = N->getOperand(1);
SDOperand N2 = N->getOperand(2);
AddToISelQueue(N1);
AddToISelQueue(N2);
return CurDAG->SelectNodeTo(N, Opc, MVT::Other, N2, N1, Chain);
}
case ISD::BRCOND: {
SDOperand Chain = N->getOperand(0);
SDOperand CC = N->getOperand(1);
AddToISelQueue(Chain);
AddToISelQueue(CC);
MachineBasicBlock *Dest =
cast<BasicBlockSDNode>(N->getOperand(2))->getBasicBlock();
//FIXME - we do NOT need long branches all the time
return CurDAG->SelectNodeTo(N, IA64::BRLCOND_NOTCALL, MVT::Other, CC,
CurDAG->getBasicBlock(Dest), Chain);
}
case ISD::CALLSEQ_START:
case ISD::CALLSEQ_END: {
int64_t Amt = cast<ConstantSDNode>(N->getOperand(1))->getValue();
unsigned Opc = N->getOpcode() == ISD::CALLSEQ_START ?
IA64::ADJUSTCALLSTACKDOWN : IA64::ADJUSTCALLSTACKUP;
SDOperand N0 = N->getOperand(0);
AddToISelQueue(N0);
return CurDAG->SelectNodeTo(N, Opc, MVT::Other, getI64Imm(Amt), N0);
}
case ISD::BR:
// FIXME: we don't need long branches all the time!
SDOperand N0 = N->getOperand(0);
AddToISelQueue(N0);
return CurDAG->SelectNodeTo(N, IA64::BRL_NOTCALL, MVT::Other,
N->getOperand(1), N0);
}
return SelectCode(Op);
}
/// createIA64DAGToDAGInstructionSelector - This pass converts a legalized DAG
/// into an IA64-specific DAG, ready for instruction scheduling.
///
FunctionPass
*llvm::createIA64DAGToDAGInstructionSelector(IA64TargetMachine &TM) {
return new IA64DAGToDAGISel(TM);
}