Experimental post-pass scheduling support. Post-pass scheduling
is currently off by default, and can be enabled with
-disable-post-RA-scheduler=false.

This doesn't have a significant impact on most code yet because it doesn't
yet do anything to address anti-dependencies and it doesn't attempt to
disambiguate memory references. Also, several popular targets
don't have pipeline descriptions yet.

The majority of the changes here are splitting the SelectionDAG-specific
code out of ScheduleDAG, so that ScheduleDAG can be moved to
libLLVMCodeGen.a. The interface between ScheduleDAG-using code and
the rest of the scheduling code is somewhat rough and will evolve.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59676 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodesEmit.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodesEmit.cpp
new file mode 100644
index 0000000..dc9313b
--- /dev/null
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodesEmit.cpp
@@ -0,0 +1,661 @@
+//===---- ScheduleDAGEmit.cpp - Emit routines for the ScheduleDAG class ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This implements the Emit routines for the ScheduleDAG class, which creates
+// MachineInstrs according to the computed schedule.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "pre-RA-sched"
+#include "llvm/CodeGen/ScheduleDAGSDNodes.h"
+#include "llvm/CodeGen/MachineConstantPool.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/MathExtras.h"
+using namespace llvm;
+
+STATISTIC(NumCommutes,   "Number of instructions commuted");
+
+/// getInstrOperandRegClass - Return register class of the operand of an
+/// instruction of the specified TargetInstrDesc.
+static const TargetRegisterClass*
+getInstrOperandRegClass(const TargetRegisterInfo *TRI, 
+                        const TargetInstrInfo *TII, const TargetInstrDesc &II,
+                        unsigned Op) {
+  if (Op >= II.getNumOperands()) {
+    assert(II.isVariadic() && "Invalid operand # of instruction");
+    return NULL;
+  }
+  if (II.OpInfo[Op].isLookupPtrRegClass())
+    return TII->getPointerRegClass();
+  return TRI->getRegClass(II.OpInfo[Op].RegClass);
+}
+
+/// EmitCopyFromReg - Generate machine code for an CopyFromReg node or an
+/// implicit physical register output.
+void ScheduleDAGSDNodes::EmitCopyFromReg(SDNode *Node, unsigned ResNo,
+                                         bool IsClone, unsigned SrcReg,
+                                         DenseMap<SDValue, unsigned> &VRBaseMap) {
+  unsigned VRBase = 0;
+  if (TargetRegisterInfo::isVirtualRegister(SrcReg)) {
+    // Just use the input register directly!
+    SDValue Op(Node, ResNo);
+    if (IsClone)
+      VRBaseMap.erase(Op);
+    bool isNew = VRBaseMap.insert(std::make_pair(Op, SrcReg)).second;
+    isNew = isNew; // Silence compiler warning.
+    assert(isNew && "Node emitted out of order - early");
+    return;
+  }
+
+  // If the node is only used by a CopyToReg and the dest reg is a vreg, use
+  // the CopyToReg'd destination register instead of creating a new vreg.
+  bool MatchReg = true;
+  const TargetRegisterClass *UseRC = NULL;
+  for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
+       UI != E; ++UI) {
+    SDNode *User = *UI;
+    bool Match = true;
+    if (User->getOpcode() == ISD::CopyToReg && 
+        User->getOperand(2).getNode() == Node &&
+        User->getOperand(2).getResNo() == ResNo) {
+      unsigned DestReg = cast<RegisterSDNode>(User->getOperand(1))->getReg();
+      if (TargetRegisterInfo::isVirtualRegister(DestReg)) {
+        VRBase = DestReg;
+        Match = false;
+      } else if (DestReg != SrcReg)
+        Match = false;
+    } else {
+      for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i) {
+        SDValue Op = User->getOperand(i);
+        if (Op.getNode() != Node || Op.getResNo() != ResNo)
+          continue;
+        MVT VT = Node->getValueType(Op.getResNo());
+        if (VT == MVT::Other || VT == MVT::Flag)
+          continue;
+        Match = false;
+        if (User->isMachineOpcode()) {
+          const TargetInstrDesc &II = TII->get(User->getMachineOpcode());
+          const TargetRegisterClass *RC =
+            getInstrOperandRegClass(TRI,TII,II,i+II.getNumDefs());
+          if (!UseRC)
+            UseRC = RC;
+          else if (RC)
+            assert(UseRC == RC &&
+                   "Multiple uses expecting different register classes!");
+        }
+      }
+    }
+    MatchReg &= Match;
+    if (VRBase)
+      break;
+  }
+
+  MVT VT = Node->getValueType(ResNo);
+  const TargetRegisterClass *SrcRC = 0, *DstRC = 0;
+  SrcRC = TRI->getPhysicalRegisterRegClass(SrcReg, VT);
+  
+  // Figure out the register class to create for the destreg.
+  if (VRBase) {
+    DstRC = MRI.getRegClass(VRBase);
+  } else if (UseRC) {
+    assert(UseRC->hasType(VT) && "Incompatible phys register def and uses!");
+    DstRC = UseRC;
+  } else {
+    DstRC = TLI->getRegClassFor(VT);
+  }
+    
+  // If all uses are reading from the src physical register and copying the
+  // register is either impossible or very expensive, then don't create a copy.
+  if (MatchReg && SrcRC->getCopyCost() < 0) {
+    VRBase = SrcReg;
+  } else {
+    // Create the reg, emit the copy.
+    VRBase = MRI.createVirtualRegister(DstRC);
+    bool Emitted =
+      TII->copyRegToReg(*BB, BB->end(), VRBase, SrcReg, DstRC, SrcRC);
+    Emitted = Emitted; // Silence compiler warning.
+    assert(Emitted && "Unable to issue a copy instruction!");
+  }
+
+  SDValue Op(Node, ResNo);
+  if (IsClone)
+    VRBaseMap.erase(Op);
+  bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second;
+  isNew = isNew; // Silence compiler warning.
+  assert(isNew && "Node emitted out of order - early");
+}
+
+/// getDstOfCopyToRegUse - If the only use of the specified result number of
+/// node is a CopyToReg, return its destination register. Return 0 otherwise.
+unsigned ScheduleDAGSDNodes::getDstOfOnlyCopyToRegUse(SDNode *Node,
+                                                      unsigned ResNo) const {
+  if (!Node->hasOneUse())
+    return 0;
+
+  SDNode *User = *Node->use_begin();
+  if (User->getOpcode() == ISD::CopyToReg && 
+      User->getOperand(2).getNode() == Node &&
+      User->getOperand(2).getResNo() == ResNo) {
+    unsigned Reg = cast<RegisterSDNode>(User->getOperand(1))->getReg();
+    if (TargetRegisterInfo::isVirtualRegister(Reg))
+      return Reg;
+  }
+  return 0;
+}
+
+void ScheduleDAGSDNodes::CreateVirtualRegisters(SDNode *Node, MachineInstr *MI,
+                                 const TargetInstrDesc &II,
+                                 DenseMap<SDValue, unsigned> &VRBaseMap) {
+  assert(Node->getMachineOpcode() != TargetInstrInfo::IMPLICIT_DEF &&
+         "IMPLICIT_DEF should have been handled as a special case elsewhere!");
+
+  for (unsigned i = 0; i < II.getNumDefs(); ++i) {
+    // If the specific node value is only used by a CopyToReg and the dest reg
+    // is a vreg, use the CopyToReg'd destination register instead of creating
+    // a new vreg.
+    unsigned VRBase = 0;
+    for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
+         UI != E; ++UI) {
+      SDNode *User = *UI;
+      if (User->getOpcode() == ISD::CopyToReg && 
+          User->getOperand(2).getNode() == Node &&
+          User->getOperand(2).getResNo() == i) {
+        unsigned Reg = cast<RegisterSDNode>(User->getOperand(1))->getReg();
+        if (TargetRegisterInfo::isVirtualRegister(Reg)) {
+          VRBase = Reg;
+          MI->addOperand(MachineOperand::CreateReg(Reg, true));
+          break;
+        }
+      }
+    }
+
+    // Create the result registers for this node and add the result regs to
+    // the machine instruction.
+    if (VRBase == 0) {
+      const TargetRegisterClass *RC = getInstrOperandRegClass(TRI, TII, II, i);
+      assert(RC && "Isn't a register operand!");
+      VRBase = MRI.createVirtualRegister(RC);
+      MI->addOperand(MachineOperand::CreateReg(VRBase, true));
+    }
+
+    SDValue Op(Node, i);
+    bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second;
+    isNew = isNew; // Silence compiler warning.
+    assert(isNew && "Node emitted out of order - early");
+  }
+}
+
+/// getVR - Return the virtual register corresponding to the specified result
+/// of the specified node.
+unsigned ScheduleDAGSDNodes::getVR(SDValue Op,
+                                   DenseMap<SDValue, unsigned> &VRBaseMap) {
+  if (Op.isMachineOpcode() &&
+      Op.getMachineOpcode() == TargetInstrInfo::IMPLICIT_DEF) {
+    // Add an IMPLICIT_DEF instruction before every use.
+    unsigned VReg = getDstOfOnlyCopyToRegUse(Op.getNode(), Op.getResNo());
+    // IMPLICIT_DEF can produce any type of result so its TargetInstrDesc
+    // does not include operand register class info.
+    if (!VReg) {
+      const TargetRegisterClass *RC = TLI->getRegClassFor(Op.getValueType());
+      VReg = MRI.createVirtualRegister(RC);
+    }
+    BuildMI(BB, TII->get(TargetInstrInfo::IMPLICIT_DEF), VReg);
+    return VReg;
+  }
+
+  DenseMap<SDValue, unsigned>::iterator I = VRBaseMap.find(Op);
+  assert(I != VRBaseMap.end() && "Node emitted out of order - late");
+  return I->second;
+}
+
+
+/// AddOperand - Add the specified operand to the specified machine instr.  II
+/// specifies the instruction information for the node, and IIOpNum is the
+/// operand number (in the II) that we are adding. IIOpNum and II are used for 
+/// assertions only.
+void ScheduleDAGSDNodes::AddOperand(MachineInstr *MI, SDValue Op,
+                                    unsigned IIOpNum,
+                                    const TargetInstrDesc *II,
+                                    DenseMap<SDValue, unsigned> &VRBaseMap) {
+  if (Op.isMachineOpcode()) {
+    // Note that this case is redundant with the final else block, but we
+    // include it because it is the most common and it makes the logic
+    // simpler here.
+    assert(Op.getValueType() != MVT::Other &&
+           Op.getValueType() != MVT::Flag &&
+           "Chain and flag operands should occur at end of operand list!");
+    // Get/emit the operand.
+    unsigned VReg = getVR(Op, VRBaseMap);
+    const TargetInstrDesc &TID = MI->getDesc();
+    bool isOptDef = IIOpNum < TID.getNumOperands() &&
+      TID.OpInfo[IIOpNum].isOptionalDef();
+    MI->addOperand(MachineOperand::CreateReg(VReg, isOptDef));
+    
+    // Verify that it is right.
+    assert(TargetRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
+#ifndef NDEBUG
+    if (II) {
+      // There may be no register class for this operand if it is a variadic
+      // argument (RC will be NULL in this case).  In this case, we just assume
+      // the regclass is ok.
+      const TargetRegisterClass *RC =
+                          getInstrOperandRegClass(TRI, TII, *II, IIOpNum);
+      assert((RC || II->isVariadic()) && "Expected reg class info!");
+      const TargetRegisterClass *VRC = MRI.getRegClass(VReg);
+      if (RC && VRC != RC) {
+        cerr << "Register class of operand and regclass of use don't agree!\n";
+        cerr << "Operand = " << IIOpNum << "\n";
+        cerr << "Op->Val = "; Op.getNode()->dump(DAG); cerr << "\n";
+        cerr << "MI = "; MI->print(cerr);
+        cerr << "VReg = " << VReg << "\n";
+        cerr << "VReg RegClass     size = " << VRC->getSize()
+             << ", align = " << VRC->getAlignment() << "\n";
+        cerr << "Expected RegClass size = " << RC->getSize()
+             << ", align = " << RC->getAlignment() << "\n";
+        cerr << "Fatal error, aborting.\n";
+        abort();
+      }
+    }
+#endif
+  } else if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
+    MI->addOperand(MachineOperand::CreateImm(C->getZExtValue()));
+  } else if (ConstantFPSDNode *F = dyn_cast<ConstantFPSDNode>(Op)) {
+    const ConstantFP *CFP = F->getConstantFPValue();
+    MI->addOperand(MachineOperand::CreateFPImm(CFP));
+  } else if (RegisterSDNode *R = dyn_cast<RegisterSDNode>(Op)) {
+    MI->addOperand(MachineOperand::CreateReg(R->getReg(), false));
+  } else if (GlobalAddressSDNode *TGA = dyn_cast<GlobalAddressSDNode>(Op)) {
+    MI->addOperand(MachineOperand::CreateGA(TGA->getGlobal(),TGA->getOffset()));
+  } else if (BasicBlockSDNode *BB = dyn_cast<BasicBlockSDNode>(Op)) {
+    MI->addOperand(MachineOperand::CreateMBB(BB->getBasicBlock()));
+  } else if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Op)) {
+    MI->addOperand(MachineOperand::CreateFI(FI->getIndex()));
+  } else if (JumpTableSDNode *JT = dyn_cast<JumpTableSDNode>(Op)) {
+    MI->addOperand(MachineOperand::CreateJTI(JT->getIndex()));
+  } else if (ConstantPoolSDNode *CP = dyn_cast<ConstantPoolSDNode>(Op)) {
+    int Offset = CP->getOffset();
+    unsigned Align = CP->getAlignment();
+    const Type *Type = CP->getType();
+    // MachineConstantPool wants an explicit alignment.
+    if (Align == 0) {
+      Align = TM.getTargetData()->getPreferredTypeAlignmentShift(Type);
+      if (Align == 0) {
+        // Alignment of vector types.  FIXME!
+        Align = TM.getTargetData()->getABITypeSize(Type);
+        Align = Log2_64(Align);
+      }
+    }
+    
+    unsigned Idx;
+    if (CP->isMachineConstantPoolEntry())
+      Idx = ConstPool->getConstantPoolIndex(CP->getMachineCPVal(), Align);
+    else
+      Idx = ConstPool->getConstantPoolIndex(CP->getConstVal(), Align);
+    MI->addOperand(MachineOperand::CreateCPI(Idx, Offset));
+  } else if (ExternalSymbolSDNode *ES = dyn_cast<ExternalSymbolSDNode>(Op)) {
+    MI->addOperand(MachineOperand::CreateES(ES->getSymbol()));
+  } else {
+    assert(Op.getValueType() != MVT::Other &&
+           Op.getValueType() != MVT::Flag &&
+           "Chain and flag operands should occur at end of operand list!");
+    unsigned VReg = getVR(Op, VRBaseMap);
+    MI->addOperand(MachineOperand::CreateReg(VReg, false));
+    
+    // Verify that it is right.  Note that the reg class of the physreg and the
+    // vreg don't necessarily need to match, but the target copy insertion has
+    // to be able to handle it.  This handles things like copies from ST(0) to
+    // an FP vreg on x86.
+    assert(TargetRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
+    if (II && !II->isVariadic()) {
+      assert(getInstrOperandRegClass(TRI, TII, *II, IIOpNum) &&
+             "Don't have operand info for this instruction!");
+    }
+  }  
+}
+
+/// getSubRegisterRegClass - Returns the register class of specified register
+/// class' "SubIdx"'th sub-register class.
+static const TargetRegisterClass*
+getSubRegisterRegClass(const TargetRegisterClass *TRC, unsigned SubIdx) {
+  // Pick the register class of the subregister
+  TargetRegisterInfo::regclass_iterator I =
+    TRC->subregclasses_begin() + SubIdx-1;
+  assert(I < TRC->subregclasses_end() && 
+         "Invalid subregister index for register class");
+  return *I;
+}
+
+/// getSuperRegisterRegClass - Returns the register class of a superreg A whose
+/// "SubIdx"'th sub-register class is the specified register class and whose
+/// type matches the specified type.
+static const TargetRegisterClass*
+getSuperRegisterRegClass(const TargetRegisterClass *TRC,
+                         unsigned SubIdx, MVT VT) {
+  // Pick the register class of the superegister for this type
+  for (TargetRegisterInfo::regclass_iterator I = TRC->superregclasses_begin(),
+         E = TRC->superregclasses_end(); I != E; ++I)
+    if ((*I)->hasType(VT) && getSubRegisterRegClass(*I, SubIdx) == TRC)
+      return *I;
+  assert(false && "Couldn't find the register class");
+  return 0;
+}
+
+/// EmitSubregNode - Generate machine code for subreg nodes.
+///
+void ScheduleDAGSDNodes::EmitSubregNode(SDNode *Node, 
+                                        DenseMap<SDValue, unsigned> &VRBaseMap) {
+  unsigned VRBase = 0;
+  unsigned Opc = Node->getMachineOpcode();
+  
+  // If the node is only used by a CopyToReg and the dest reg is a vreg, use
+  // the CopyToReg'd destination register instead of creating a new vreg.
+  for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
+       UI != E; ++UI) {
+    SDNode *User = *UI;
+    if (User->getOpcode() == ISD::CopyToReg && 
+        User->getOperand(2).getNode() == Node) {
+      unsigned DestReg = cast<RegisterSDNode>(User->getOperand(1))->getReg();
+      if (TargetRegisterInfo::isVirtualRegister(DestReg)) {
+        VRBase = DestReg;
+        break;
+      }
+    }
+  }
+  
+  if (Opc == TargetInstrInfo::EXTRACT_SUBREG) {
+    unsigned SubIdx = cast<ConstantSDNode>(Node->getOperand(1))->getZExtValue();
+
+    // Create the extract_subreg machine instruction.
+    MachineInstr *MI = BuildMI(*MF, TII->get(TargetInstrInfo::EXTRACT_SUBREG));
+
+    // Figure out the register class to create for the destreg.
+    unsigned VReg = getVR(Node->getOperand(0), VRBaseMap);
+    const TargetRegisterClass *TRC = MRI.getRegClass(VReg);
+    const TargetRegisterClass *SRC = getSubRegisterRegClass(TRC, SubIdx);
+
+    if (VRBase) {
+      // Grab the destination register
+#ifndef NDEBUG
+      const TargetRegisterClass *DRC = MRI.getRegClass(VRBase);
+      assert(SRC && DRC && SRC == DRC && 
+             "Source subregister and destination must have the same class");
+#endif
+    } else {
+      // Create the reg
+      assert(SRC && "Couldn't find source register class");
+      VRBase = MRI.createVirtualRegister(SRC);
+    }
+    
+    // Add def, source, and subreg index
+    MI->addOperand(MachineOperand::CreateReg(VRBase, true));
+    AddOperand(MI, Node->getOperand(0), 0, 0, VRBaseMap);
+    MI->addOperand(MachineOperand::CreateImm(SubIdx));
+    BB->push_back(MI);    
+  } else if (Opc == TargetInstrInfo::INSERT_SUBREG ||
+             Opc == TargetInstrInfo::SUBREG_TO_REG) {
+    SDValue N0 = Node->getOperand(0);
+    SDValue N1 = Node->getOperand(1);
+    SDValue N2 = Node->getOperand(2);
+    unsigned SubReg = getVR(N1, VRBaseMap);
+    unsigned SubIdx = cast<ConstantSDNode>(N2)->getZExtValue();
+    
+      
+    // Figure out the register class to create for the destreg.
+    const TargetRegisterClass *TRC = 0;
+    if (VRBase) {
+      TRC = MRI.getRegClass(VRBase);
+    } else {
+      TRC = getSuperRegisterRegClass(MRI.getRegClass(SubReg), SubIdx, 
+                                     Node->getValueType(0));
+      assert(TRC && "Couldn't determine register class for insert_subreg");
+      VRBase = MRI.createVirtualRegister(TRC); // Create the reg
+    }
+    
+    // Create the insert_subreg or subreg_to_reg machine instruction.
+    MachineInstr *MI = BuildMI(*MF, TII->get(Opc));
+    MI->addOperand(MachineOperand::CreateReg(VRBase, true));
+    
+    // If creating a subreg_to_reg, then the first input operand
+    // is an implicit value immediate, otherwise it's a register
+    if (Opc == TargetInstrInfo::SUBREG_TO_REG) {
+      const ConstantSDNode *SD = cast<ConstantSDNode>(N0);
+      MI->addOperand(MachineOperand::CreateImm(SD->getZExtValue()));
+    } else
+      AddOperand(MI, N0, 0, 0, VRBaseMap);
+    // Add the subregster being inserted
+    AddOperand(MI, N1, 0, 0, VRBaseMap);
+    MI->addOperand(MachineOperand::CreateImm(SubIdx));
+    BB->push_back(MI);
+  } else
+    assert(0 && "Node is not insert_subreg, extract_subreg, or subreg_to_reg");
+     
+  SDValue Op(Node, 0);
+  bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second;
+  isNew = isNew; // Silence compiler warning.
+  assert(isNew && "Node emitted out of order - early");
+}
+
+/// EmitNode - Generate machine code for an node and needed dependencies.
+///
+void ScheduleDAGSDNodes::EmitNode(SDNode *Node, bool IsClone,
+                                  DenseMap<SDValue, unsigned> &VRBaseMap) {
+  // If machine instruction
+  if (Node->isMachineOpcode()) {
+    unsigned Opc = Node->getMachineOpcode();
+    
+    // Handle subreg insert/extract specially
+    if (Opc == TargetInstrInfo::EXTRACT_SUBREG || 
+        Opc == TargetInstrInfo::INSERT_SUBREG ||
+        Opc == TargetInstrInfo::SUBREG_TO_REG) {
+      EmitSubregNode(Node, VRBaseMap);
+      return;
+    }
+
+    if (Opc == TargetInstrInfo::IMPLICIT_DEF)
+      // We want a unique VR for each IMPLICIT_DEF use.
+      return;
+    
+    const TargetInstrDesc &II = TII->get(Opc);
+    unsigned NumResults = CountResults(Node);
+    unsigned NodeOperands = CountOperands(Node);
+    unsigned MemOperandsEnd = ComputeMemOperandsEnd(Node);
+    bool HasPhysRegOuts = (NumResults > II.getNumDefs()) &&
+                          II.getImplicitDefs() != 0;
+#ifndef NDEBUG
+    unsigned NumMIOperands = NodeOperands + NumResults;
+    assert((II.getNumOperands() == NumMIOperands ||
+            HasPhysRegOuts || II.isVariadic()) &&
+           "#operands for dag node doesn't match .td file!"); 
+#endif
+
+    // Create the new machine instruction.
+    MachineInstr *MI = BuildMI(*MF, II);
+    
+    // Add result register values for things that are defined by this
+    // instruction.
+    if (NumResults)
+      CreateVirtualRegisters(Node, MI, II, VRBaseMap);
+    
+    // Emit all of the actual operands of this instruction, adding them to the
+    // instruction as appropriate.
+    for (unsigned i = 0; i != NodeOperands; ++i)
+      AddOperand(MI, Node->getOperand(i), i+II.getNumDefs(), &II, VRBaseMap);
+
+    // Emit all of the memory operands of this instruction
+    for (unsigned i = NodeOperands; i != MemOperandsEnd; ++i)
+      AddMemOperand(MI, cast<MemOperandSDNode>(Node->getOperand(i))->MO);
+
+    // Commute node if it has been determined to be profitable.
+    if (CommuteSet.count(Node)) {
+      MachineInstr *NewMI = TII->commuteInstruction(MI);
+      if (NewMI == 0)
+        DOUT << "Sched: COMMUTING FAILED!\n";
+      else {
+        DOUT << "Sched: COMMUTED TO: " << *NewMI;
+        if (MI != NewMI) {
+          MF->DeleteMachineInstr(MI);
+          MI = NewMI;
+        }
+        ++NumCommutes;
+      }
+    }
+
+    if (II.usesCustomDAGSchedInsertionHook())
+      // Insert this instruction into the basic block using a target
+      // specific inserter which may returns a new basic block.
+      BB = TLI->EmitInstrWithCustomInserter(MI, BB);
+    else
+      BB->push_back(MI);
+
+    // Additional results must be an physical register def.
+    if (HasPhysRegOuts) {
+      for (unsigned i = II.getNumDefs(); i < NumResults; ++i) {
+        unsigned Reg = II.getImplicitDefs()[i - II.getNumDefs()];
+        if (Node->hasAnyUseOfValue(i))
+          EmitCopyFromReg(Node, i, IsClone, Reg, VRBaseMap);
+      }
+    }
+    return;
+  }
+
+  switch (Node->getOpcode()) {
+  default:
+#ifndef NDEBUG
+    Node->dump(DAG);
+#endif
+    assert(0 && "This target-independent node should have been selected!");
+    break;
+  case ISD::EntryToken:
+    assert(0 && "EntryToken should have been excluded from the schedule!");
+    break;
+  case ISD::TokenFactor: // fall thru
+    break;
+  case ISD::CopyToReg: {
+    unsigned SrcReg;
+    SDValue SrcVal = Node->getOperand(2);
+    if (RegisterSDNode *R = dyn_cast<RegisterSDNode>(SrcVal))
+      SrcReg = R->getReg();
+    else
+      SrcReg = getVR(SrcVal, VRBaseMap);
+      
+    unsigned DestReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
+    if (SrcReg == DestReg) // Coalesced away the copy? Ignore.
+      break;
+      
+    const TargetRegisterClass *SrcTRC = 0, *DstTRC = 0;
+    // Get the register classes of the src/dst.
+    if (TargetRegisterInfo::isVirtualRegister(SrcReg))
+      SrcTRC = MRI.getRegClass(SrcReg);
+    else
+      SrcTRC = TRI->getPhysicalRegisterRegClass(SrcReg,SrcVal.getValueType());
+
+    if (TargetRegisterInfo::isVirtualRegister(DestReg))
+      DstTRC = MRI.getRegClass(DestReg);
+    else
+      DstTRC = TRI->getPhysicalRegisterRegClass(DestReg,
+                                            Node->getOperand(1).getValueType());
+    TII->copyRegToReg(*BB, BB->end(), DestReg, SrcReg, DstTRC, SrcTRC);
+    break;
+  }
+  case ISD::CopyFromReg: {
+    unsigned SrcReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
+    EmitCopyFromReg(Node, 0, IsClone, SrcReg, VRBaseMap);
+    break;
+  }
+  case ISD::INLINEASM: {
+    unsigned NumOps = Node->getNumOperands();
+    if (Node->getOperand(NumOps-1).getValueType() == MVT::Flag)
+      --NumOps;  // Ignore the flag operand.
+      
+    // Create the inline asm machine instruction.
+    MachineInstr *MI = BuildMI(*MF, TII->get(TargetInstrInfo::INLINEASM));
+
+    // Add the asm string as an external symbol operand.
+    const char *AsmStr =
+      cast<ExternalSymbolSDNode>(Node->getOperand(1))->getSymbol();
+    MI->addOperand(MachineOperand::CreateES(AsmStr));
+      
+    // Add all of the operand registers to the instruction.
+    for (unsigned i = 2; i != NumOps;) {
+      unsigned Flags =
+        cast<ConstantSDNode>(Node->getOperand(i))->getZExtValue();
+      unsigned NumVals = Flags >> 3;
+        
+      MI->addOperand(MachineOperand::CreateImm(Flags));
+      ++i;  // Skip the ID value.
+        
+      switch (Flags & 7) {
+      default: assert(0 && "Bad flags!");
+      case 2:   // Def of register.
+        for (; NumVals; --NumVals, ++i) {
+          unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
+          MI->addOperand(MachineOperand::CreateReg(Reg, true));
+        }
+        break;
+      case 6:   // Def of earlyclobber register.
+        for (; NumVals; --NumVals, ++i) {
+          unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
+          MI->addOperand(MachineOperand::CreateReg(Reg, true, false, false, 
+                                                   false, 0, true));
+        }
+        break;
+      case 1:  // Use of register.
+      case 3:  // Immediate.
+      case 4:  // Addressing mode.
+        // The addressing mode has been selected, just add all of the
+        // operands to the machine instruction.
+        for (; NumVals; --NumVals, ++i)
+          AddOperand(MI, Node->getOperand(i), 0, 0, VRBaseMap);
+        break;
+      }
+    }
+    BB->push_back(MI);
+    break;
+  }
+  }
+}
+
+/// EmitSchedule - Emit the machine code in scheduled order.
+MachineBasicBlock *ScheduleDAGSDNodes::EmitSchedule() {
+  DenseMap<SDValue, unsigned> VRBaseMap;
+  DenseMap<SUnit*, unsigned> CopyVRBaseMap;
+  for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
+    SUnit *SU = Sequence[i];
+    if (!SU) {
+      // Null SUnit* is a noop.
+      EmitNoop();
+      continue;
+    }
+
+    // For pre-regalloc scheduling, create instructions corresponding to the
+    // SDNode and any flagged SDNodes and append them to the block.
+    SmallVector<SDNode *, 4> FlaggedNodes;
+    for (SDNode *N = SU->getNode()->getFlaggedNode(); N; N = N->getFlaggedNode())
+      FlaggedNodes.push_back(N);
+    while (!FlaggedNodes.empty()) {
+      EmitNode(FlaggedNodes.back(), SU->OrigNode != SU, VRBaseMap);
+      FlaggedNodes.pop_back();
+    }
+    if (!SU->getNode())
+      EmitCrossRCCopy(SU, CopyVRBaseMap);
+    else
+      EmitNode(SU->getNode(), SU->OrigNode != SU, VRBaseMap);
+  }
+
+  return BB;
+}