lib/CodeGen/SelectionDAG/ScheduleDAGSDNodesEmit.cpp

   1 //===---- ScheduleDAGEmit.cpp - Emit routines for the ScheduleDAG class ---===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This implements the Emit routines for the ScheduleDAG class, which creates
  11 // MachineInstrs according to the computed schedule.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #define DEBUG_TYPE "pre-RA-sched"
  16 #include "ScheduleDAGSDNodes.h"
  17 #include "llvm/CodeGen/MachineConstantPool.h"
  18 #include "llvm/CodeGen/MachineFunction.h"
  19 #include "llvm/CodeGen/MachineInstrBuilder.h"
  20 #include "llvm/CodeGen/MachineRegisterInfo.h"
  21 #include "llvm/Target/TargetData.h"
  22 #include "llvm/Target/TargetMachine.h"
  23 #include "llvm/Target/TargetInstrInfo.h"
  24 #include "llvm/Target/TargetLowering.h"
  25 #include "llvm/ADT/Statistic.h"
  26 #include "llvm/Support/CommandLine.h"
  27 #include "llvm/Support/Debug.h"
  28 #include "llvm/Support/ErrorHandling.h"
  29 #include "llvm/Support/MathExtras.h"
  30 using namespace llvm;
  31
  32 /// EmitCopyFromReg - Generate machine code for an CopyFromReg node or an
  33 /// implicit physical register output.
  34 void ScheduleDAGSDNodes::
  35 EmitCopyFromReg(SDNode *Node, unsigned ResNo, bool IsClone, bool IsCloned,
  36                 unsigned SrcReg, DenseMap<SDValue, unsigned> &VRBaseMap) {
  37   unsigned VRBase = 0;
  38   if (TargetRegisterInfo::isVirtualRegister(SrcReg)) {
  39     // Just use the input register directly!
  40     SDValue Op(Node, ResNo);
  41     if (IsClone)
  42       VRBaseMap.erase(Op);
  43     bool isNew = VRBaseMap.insert(std::make_pair(Op, SrcReg)).second;
  44     isNew = isNew; // Silence compiler warning.
  45     assert(isNew && "Node emitted out of order - early");
  46     return;
  47   }
  48
  49   // If the node is only used by a CopyToReg and the dest reg is a vreg, use
  50   // the CopyToReg'd destination register instead of creating a new vreg.
  51   bool MatchReg = true;
  52   const TargetRegisterClass *UseRC = NULL;
  53   if (!IsClone && !IsCloned)
  54     for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
  55          UI != E; ++UI) {
  56       SDNode *User = *UI;
  57       bool Match = true;
  58       if (User->getOpcode() == ISD::CopyToReg &&
  59           User->getOperand(2).getNode() == Node &&
  60           User->getOperand(2).getResNo() == ResNo) {
  61         unsigned DestReg = cast<RegisterSDNode>(User->getOperand(1))->getReg();
  62         if (TargetRegisterInfo::isVirtualRegister(DestReg)) {
  63           VRBase = DestReg;
  64           Match = false;
  65         } else if (DestReg != SrcReg)
  66           Match = false;
  67       } else {
  68         for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i) {
  69           SDValue Op = User->getOperand(i);
  70           if (Op.getNode() != Node || Op.getResNo() != ResNo)
  71             continue;
  72           EVT VT = Node->getValueType(Op.getResNo());
  73           if (VT == MVT::Other || VT == MVT::Flag)
  74             continue;
  75           Match = false;
  76           if (User->isMachineOpcode()) {
  77             const TargetInstrDesc &II = TII->get(User->getMachineOpcode());
  78             const TargetRegisterClass *RC = 0;
  79             if (i+II.getNumDefs() < II.getNumOperands())
  80               RC = II.OpInfo[i+II.getNumDefs()].getRegClass(TRI);
  81             if (!UseRC)
  82               UseRC = RC;
  83             else if (RC) {
  84               const TargetRegisterClass *ComRC = getCommonSubClass(UseRC, RC);
  85               // If multiple uses expect disjoint register classes, we emit
  86               // copies in AddRegisterOperand.
  87               if (ComRC)
  88                 UseRC = ComRC;
  89             }
  90           }
  91         }
  92       }
  93       MatchReg &= Match;
  94       if (VRBase)
  95         break;
  96     }
  97
  98   EVT VT = Node->getValueType(ResNo);
  99   const TargetRegisterClass *SrcRC = 0, *DstRC = 0;
 100   SrcRC = TRI->getPhysicalRegisterRegClass(SrcReg, VT);
 101
 102   // Figure out the register class to create for the destreg.
 103   if (VRBase) {
 104     DstRC = MRI.getRegClass(VRBase);
 105   } else if (UseRC) {
 106     assert(UseRC->hasType(VT) && "Incompatible phys register def and uses!");
 107     DstRC = UseRC;
 108   } else {
 109     DstRC = TLI->getRegClassFor(VT);
 110   }
 111
 112   // If all uses are reading from the src physical register and copying the
 113   // register is either impossible or very expensive, then don't create a copy.
 114   if (MatchReg && SrcRC->getCopyCost() < 0) {
 115     VRBase = SrcReg;
 116   } else {
 117     // Create the reg, emit the copy.
 118     VRBase = MRI.createVirtualRegister(DstRC);
 119     bool Emitted = TII->copyRegToReg(*BB, InsertPos, VRBase, SrcReg,
 120                                      DstRC, SrcRC);
 121
 122     assert(Emitted && "Unable to issue a copy instruction!\n");
 123     (void) Emitted;
 124   }
 125
 126   SDValue Op(Node, ResNo);
 127   if (IsClone)
 128     VRBaseMap.erase(Op);
 129   bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second;
 130   isNew = isNew; // Silence compiler warning.
 131   assert(isNew && "Node emitted out of order - early");
 132 }
 133
 134 /// getDstOfCopyToRegUse - If the only use of the specified result number of
 135 /// node is a CopyToReg, return its destination register. Return 0 otherwise.
 136 unsigned ScheduleDAGSDNodes::getDstOfOnlyCopyToRegUse(SDNode *Node,
 137                                                       unsigned ResNo) const {
 138   if (!Node->hasOneUse())
 139     return 0;
 140
 141   SDNode *User = *Node->use_begin();
 142   if (User->getOpcode() == ISD::CopyToReg &&
 143       User->getOperand(2).getNode() == Node &&
 144       User->getOperand(2).getResNo() == ResNo) {
 145     unsigned Reg = cast<RegisterSDNode>(User->getOperand(1))->getReg();
 146     if (TargetRegisterInfo::isVirtualRegister(Reg))
 147       return Reg;
 148   }
 149   return 0;
 150 }
 151
 152 void ScheduleDAGSDNodes::CreateVirtualRegisters(SDNode *Node, MachineInstr *MI,
 153                                        const TargetInstrDesc &II,
 154                                        bool IsClone, bool IsCloned,
 155                                        DenseMap<SDValue, unsigned> &VRBaseMap) {
 156   assert(Node->getMachineOpcode() != TargetInstrInfo::IMPLICIT_DEF &&
 157          "IMPLICIT_DEF should have been handled as a special case elsewhere!");
 158
 159   for (unsigned i = 0; i < II.getNumDefs(); ++i) {
 160     // If the specific node value is only used by a CopyToReg and the dest reg
 161     // is a vreg in the same register class, use the CopyToReg'd destination
 162     // register instead of creating a new vreg.
 163     unsigned VRBase = 0;
 164     const TargetRegisterClass *RC = II.OpInfo[i].getRegClass(TRI);
 165     if (II.OpInfo[i].isOptionalDef()) {
 166       // Optional def must be a physical register.
 167       unsigned NumResults = CountResults(Node);
 168       VRBase = cast<RegisterSDNode>(Node->getOperand(i-NumResults))->getReg();
 169       assert(TargetRegisterInfo::isPhysicalRegister(VRBase));
 170       MI->addOperand(MachineOperand::CreateReg(VRBase, true));
 171     }
 172
 173     if (!VRBase && !IsClone && !IsCloned)
 174       for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
 175            UI != E; ++UI) {
 176         SDNode *User = *UI;
 177         if (User->getOpcode() == ISD::CopyToReg &&
 178             User->getOperand(2).getNode() == Node &&
 179             User->getOperand(2).getResNo() == i) {
 180           unsigned Reg = cast<RegisterSDNode>(User->getOperand(1))->getReg();
 181           if (TargetRegisterInfo::isVirtualRegister(Reg)) {
 182             const TargetRegisterClass *RegRC = MRI.getRegClass(Reg);
 183             if (RegRC == RC) {
 184               VRBase = Reg;
 185               MI->addOperand(MachineOperand::CreateReg(Reg, true));
 186               break;
 187             }
 188           }
 189         }
 190       }
 191
 192     // Create the result registers for this node and add the result regs to
 193     // the machine instruction.
 194     if (VRBase == 0) {
 195       assert(RC && "Isn't a register operand!");
 196       VRBase = MRI.createVirtualRegister(RC);
 197       MI->addOperand(MachineOperand::CreateReg(VRBase, true));
 198     }
 199
 200     SDValue Op(Node, i);
 201     if (IsClone)
 202       VRBaseMap.erase(Op);
 203     bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second;
 204     isNew = isNew; // Silence compiler warning.
 205     assert(isNew && "Node emitted out of order - early");
 206   }
 207 }
 208
 209 /// getVR - Return the virtual register corresponding to the specified result
 210 /// of the specified node.
 211 unsigned ScheduleDAGSDNodes::getVR(SDValue Op,
 212                                    DenseMap<SDValue, unsigned> &VRBaseMap) {
 213   if (Op.isMachineOpcode() &&
 214       Op.getMachineOpcode() == TargetInstrInfo::IMPLICIT_DEF) {
 215     // Add an IMPLICIT_DEF instruction before every use.
 216     unsigned VReg = getDstOfOnlyCopyToRegUse(Op.getNode(), Op.getResNo());
 217     // IMPLICIT_DEF can produce any type of result so its TargetInstrDesc
 218     // does not include operand register class info.
 219     if (!VReg) {
 220       const TargetRegisterClass *RC = TLI->getRegClassFor(Op.getValueType());
 221       VReg = MRI.createVirtualRegister(RC);
 222     }
 223     BuildMI(BB, Op.getDebugLoc(), TII->get(TargetInstrInfo::IMPLICIT_DEF),VReg);
 224     return VReg;
 225   }
 226
 227   DenseMap<SDValue, unsigned>::iterator I = VRBaseMap.find(Op);
 228   assert(I != VRBaseMap.end() && "Node emitted out of order - late");
 229   return I->second;
 230 }
 231
 232
 233 /// AddRegisterOperand - Add the specified register as an operand to the
 234 /// specified machine instr. Insert register copies if the register is
 235 /// not in the required register class.
 236 void
 237 ScheduleDAGSDNodes::AddRegisterOperand(MachineInstr *MI, SDValue Op,
 238                                        unsigned IIOpNum,
 239                                        const TargetInstrDesc *II,
 240                                        DenseMap<SDValue, unsigned> &VRBaseMap) {
 241   assert(Op.getValueType() != MVT::Other &&
 242          Op.getValueType() != MVT::Flag &&
 243          "Chain and flag operands should occur at end of operand list!");
 244   // Get/emit the operand.
 245   unsigned VReg = getVR(Op, VRBaseMap);
 246   assert(TargetRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
 247
 248   const TargetInstrDesc &TID = MI->getDesc();
 249   bool isOptDef = IIOpNum < TID.getNumOperands() &&
 250     TID.OpInfo[IIOpNum].isOptionalDef();
 251
 252   // If the instruction requires a register in a different class, create
 253   // a new virtual register and copy the value into it.
 254   if (II) {
 255     const TargetRegisterClass *SrcRC = MRI.getRegClass(VReg);
 256     const TargetRegisterClass *DstRC = 0;
 257     if (IIOpNum < II->getNumOperands())
 258       DstRC = II->OpInfo[IIOpNum].getRegClass(TRI);
 259     assert((DstRC || (TID.isVariadic() && IIOpNum >= TID.getNumOperands())) &&
 260            "Don't have operand info for this instruction!");
 261     if (DstRC && SrcRC != DstRC && !SrcRC->hasSuperClass(DstRC)) {
 262       unsigned NewVReg = MRI.createVirtualRegister(DstRC);
 263       bool Emitted = TII->copyRegToReg(*BB, InsertPos, NewVReg, VReg,
 264                                        DstRC, SrcRC);
 265       assert(Emitted && "Unable to issue a copy instruction!\n");
 266       (void) Emitted;
 267       VReg = NewVReg;
 268     }
 269   }
 270
 271   MI->addOperand(MachineOperand::CreateReg(VReg, isOptDef));
 272 }
 273
 274 /// AddOperand - Add the specified operand to the specified machine instr.  II
 275 /// specifies the instruction information for the node, and IIOpNum is the
 276 /// operand number (in the II) that we are adding. IIOpNum and II are used for
 277 /// assertions only.
 278 void ScheduleDAGSDNodes::AddOperand(MachineInstr *MI, SDValue Op,
 279                                     unsigned IIOpNum,
 280                                     const TargetInstrDesc *II,
 281                                     DenseMap<SDValue, unsigned> &VRBaseMap) {
 282   if (Op.isMachineOpcode()) {
 283     AddRegisterOperand(MI, Op, IIOpNum, II, VRBaseMap);
 284   } else if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
 285     MI->addOperand(MachineOperand::CreateImm(C->getZExtValue()));
 286   } else if (ConstantFPSDNode *F = dyn_cast<ConstantFPSDNode>(Op)) {
 287     const ConstantFP *CFP = F->getConstantFPValue();
 288     MI->addOperand(MachineOperand::CreateFPImm(CFP));
 289   } else if (RegisterSDNode *R = dyn_cast<RegisterSDNode>(Op)) {
 290     MI->addOperand(MachineOperand::CreateReg(R->getReg(), false));
 291   } else if (GlobalAddressSDNode *TGA = dyn_cast<GlobalAddressSDNode>(Op)) {
 292     MI->addOperand(MachineOperand::CreateGA(TGA->getGlobal(), TGA->getOffset(),
 293                                             TGA->getTargetFlags()));
 294   } else if (BasicBlockSDNode *BBNode = dyn_cast<BasicBlockSDNode>(Op)) {
 295     MI->addOperand(MachineOperand::CreateMBB(BBNode->getBasicBlock()));
 296   } else if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Op)) {
 297     MI->addOperand(MachineOperand::CreateFI(FI->getIndex()));
 298   } else if (JumpTableSDNode *JT = dyn_cast<JumpTableSDNode>(Op)) {
 299     MI->addOperand(MachineOperand::CreateJTI(JT->getIndex(),
 300                                              JT->getTargetFlags()));
 301   } else if (ConstantPoolSDNode *CP = dyn_cast<ConstantPoolSDNode>(Op)) {
 302     int Offset = CP->getOffset();
 303     unsigned Align = CP->getAlignment();
 304     const Type *Type = CP->getType();
 305     // MachineConstantPool wants an explicit alignment.
 306     if (Align == 0) {
 307       Align = TM.getTargetData()->getPrefTypeAlignment(Type);
 308       if (Align == 0) {
 309         // Alignment of vector types.  FIXME!
 310         Align = TM.getTargetData()->getTypeAllocSize(Type);
 311       }
 312     }
 313
 314     unsigned Idx;
 315     if (CP->isMachineConstantPoolEntry())
 316       Idx = ConstPool->getConstantPoolIndex(CP->getMachineCPVal(), Align);
 317     else
 318       Idx = ConstPool->getConstantPoolIndex(CP->getConstVal(), Align);
 319     MI->addOperand(MachineOperand::CreateCPI(Idx, Offset,
 320                                              CP->getTargetFlags()));
 321   } else if (ExternalSymbolSDNode *ES = dyn_cast<ExternalSymbolSDNode>(Op)) {
 322     MI->addOperand(MachineOperand::CreateES(ES->getSymbol(),
 323                                             ES->getTargetFlags()));
 324   } else {
 325     assert(Op.getValueType() != MVT::Other &&
 326            Op.getValueType() != MVT::Flag &&
 327            "Chain and flag operands should occur at end of operand list!");
 328     AddRegisterOperand(MI, Op, IIOpNum, II, VRBaseMap);
 329   }
 330 }
 331
 332 /// getSuperRegisterRegClass - Returns the register class of a superreg A whose
 333 /// "SubIdx"'th sub-register class is the specified register class and whose
 334 /// type matches the specified type.
 335 static const TargetRegisterClass*
 336 getSuperRegisterRegClass(const TargetRegisterClass *TRC,
 337                          unsigned SubIdx, EVT VT) {
 338   // Pick the register class of the superegister for this type
 339   for (TargetRegisterInfo::regclass_iterator I = TRC->superregclasses_begin(),
 340          E = TRC->superregclasses_end(); I != E; ++I)
 341     if ((*I)->hasType(VT) && (*I)->getSubRegisterRegClass(SubIdx) == TRC)
 342       return *I;
 343   assert(false && "Couldn't find the register class");
 344   return 0;
 345 }
 346
 347 /// EmitSubregNode - Generate machine code for subreg nodes.
 348 ///
 349 void ScheduleDAGSDNodes::EmitSubregNode(SDNode *Node,
 350                                         DenseMap<SDValue, unsigned> &VRBaseMap){
 351   unsigned VRBase = 0;
 352   unsigned Opc = Node->getMachineOpcode();
 353
 354   // If the node is only used by a CopyToReg and the dest reg is a vreg, use
 355   // the CopyToReg'd destination register instead of creating a new vreg.
 356   for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
 357        UI != E; ++UI) {
 358     SDNode *User = *UI;
 359     if (User->getOpcode() == ISD::CopyToReg &&
 360         User->getOperand(2).getNode() == Node) {
 361       unsigned DestReg = cast<RegisterSDNode>(User->getOperand(1))->getReg();
 362       if (TargetRegisterInfo::isVirtualRegister(DestReg)) {
 363         VRBase = DestReg;
 364         break;
 365       }
 366     }
 367   }
 368
 369   if (Opc == TargetInstrInfo::EXTRACT_SUBREG) {
 370     unsigned SubIdx = cast<ConstantSDNode>(Node->getOperand(1))->getZExtValue();
 371
 372     // Create the extract_subreg machine instruction.
 373     MachineInstr *MI = BuildMI(MF, Node->getDebugLoc(),
 374                                TII->get(TargetInstrInfo::EXTRACT_SUBREG));
 375
 376     // Figure out the register class to create for the destreg.
 377     unsigned VReg = getVR(Node->getOperand(0), VRBaseMap);
 378     const TargetRegisterClass *TRC = MRI.getRegClass(VReg);
 379     const TargetRegisterClass *SRC = TRC->getSubRegisterRegClass(SubIdx);
 380     assert(SRC && "Invalid subregister index in EXTRACT_SUBREG");
 381
 382     // Figure out the register class to create for the destreg.
 383     // Note that if we're going to directly use an existing register,
 384     // it must be precisely the required class, and not a subclass
 385     // thereof.
 386     if (VRBase == 0 || SRC != MRI.getRegClass(VRBase)) {
 387       // Create the reg
 388       assert(SRC && "Couldn't find source register class");
 389       VRBase = MRI.createVirtualRegister(SRC);
 390     }
 391
 392     // Add def, source, and subreg index
 393     MI->addOperand(MachineOperand::CreateReg(VRBase, true));
 394     AddOperand(MI, Node->getOperand(0), 0, 0, VRBaseMap);
 395     MI->addOperand(MachineOperand::CreateImm(SubIdx));
 396     BB->insert(InsertPos, MI);
 397   } else if (Opc == TargetInstrInfo::INSERT_SUBREG ||
 398              Opc == TargetInstrInfo::SUBREG_TO_REG) {
 399     SDValue N0 = Node->getOperand(0);
 400     SDValue N1 = Node->getOperand(1);
 401     SDValue N2 = Node->getOperand(2);
 402     unsigned SubReg = getVR(N1, VRBaseMap);
 403     unsigned SubIdx = cast<ConstantSDNode>(N2)->getZExtValue();
 404     const TargetRegisterClass *TRC = MRI.getRegClass(SubReg);
 405     const TargetRegisterClass *SRC =
 406       getSuperRegisterRegClass(TRC, SubIdx,
 407                                Node->getValueType(0));
 408
 409     // Figure out the register class to create for the destreg.
 410     // Note that if we're going to directly use an existing register,
 411     // it must be precisely the required class, and not a subclass
 412     // thereof.
 413     if (VRBase == 0 || SRC != MRI.getRegClass(VRBase)) {
 414       // Create the reg
 415       assert(SRC && "Couldn't find source register class");
 416       VRBase = MRI.createVirtualRegister(SRC);
 417     }
 418
 419     // Create the insert_subreg or subreg_to_reg machine instruction.
 420     MachineInstr *MI = BuildMI(MF, Node->getDebugLoc(), TII->get(Opc));
 421     MI->addOperand(MachineOperand::CreateReg(VRBase, true));
 422
 423     // If creating a subreg_to_reg, then the first input operand
 424     // is an implicit value immediate, otherwise it's a register
 425     if (Opc == TargetInstrInfo::SUBREG_TO_REG) {
 426       const ConstantSDNode *SD = cast<ConstantSDNode>(N0);
 427       MI->addOperand(MachineOperand::CreateImm(SD->getZExtValue()));
 428     } else
 429       AddOperand(MI, N0, 0, 0, VRBaseMap);
 430     // Add the subregster being inserted
 431     AddOperand(MI, N1, 0, 0, VRBaseMap);
 432     MI->addOperand(MachineOperand::CreateImm(SubIdx));
 433     BB->insert(InsertPos, MI);
 434   } else
 435     llvm_unreachable("Node is not insert_subreg, extract_subreg, or subreg_to_reg");
 436
 437   SDValue Op(Node, 0);
 438   bool isNew = VRBaseMap.insert(std::make_pair(Op, VRBase)).second;
 439   isNew = isNew; // Silence compiler warning.
 440   assert(isNew && "Node emitted out of order - early");
 441 }
 442
 443 /// EmitCopyToRegClassNode - Generate machine code for COPY_TO_REGCLASS nodes.
 444 /// COPY_TO_REGCLASS is just a normal copy, except that the destination
 445 /// register is constrained to be in a particular register class.
 446 ///
 447 void
 448 ScheduleDAGSDNodes::EmitCopyToRegClassNode(SDNode *Node,
 449                                        DenseMap<SDValue, unsigned> &VRBaseMap) {
 450   unsigned VReg = getVR(Node->getOperand(0), VRBaseMap);
 451   const TargetRegisterClass *SrcRC = MRI.getRegClass(VReg);
 452
 453   unsigned DstRCIdx = cast<ConstantSDNode>(Node->getOperand(1))->getZExtValue();
 454   const TargetRegisterClass *DstRC = TRI->getRegClass(DstRCIdx);
 455
 456   // Create the new VReg in the destination class and emit a copy.
 457   unsigned NewVReg = MRI.createVirtualRegister(DstRC);
 458   bool Emitted = TII->copyRegToReg(*BB, InsertPos, NewVReg, VReg,
 459                                    DstRC, SrcRC);
 460   assert(Emitted &&
 461          "Unable to issue a copy instruction for a COPY_TO_REGCLASS node!\n");
 462   (void) Emitted;
 463
 464   SDValue Op(Node, 0);
 465   bool isNew = VRBaseMap.insert(std::make_pair(Op, NewVReg)).second;
 466   isNew = isNew; // Silence compiler warning.
 467   assert(isNew && "Node emitted out of order - early");
 468 }
 469
 470 /// EmitNode - Generate machine code for an node and needed dependencies.
 471 ///
 472 void ScheduleDAGSDNodes::EmitNode(SDNode *Node, bool IsClone, bool IsCloned,
 473                                   DenseMap<SDValue, unsigned> &VRBaseMap) {
 474   // If machine instruction
 475   if (Node->isMachineOpcode()) {
 476     unsigned Opc = Node->getMachineOpcode();
 477
 478     // Handle subreg insert/extract specially
 479     if (Opc == TargetInstrInfo::EXTRACT_SUBREG ||
 480         Opc == TargetInstrInfo::INSERT_SUBREG ||
 481         Opc == TargetInstrInfo::SUBREG_TO_REG) {
 482       EmitSubregNode(Node, VRBaseMap);
 483       return;
 484     }
 485
 486     // Handle COPY_TO_REGCLASS specially.
 487     if (Opc == TargetInstrInfo::COPY_TO_REGCLASS) {
 488       EmitCopyToRegClassNode(Node, VRBaseMap);
 489       return;
 490     }
 491
 492     if (Opc == TargetInstrInfo::IMPLICIT_DEF)
 493       // We want a unique VR for each IMPLICIT_DEF use.
 494       return;
 495
 496     const TargetInstrDesc &II = TII->get(Opc);
 497     unsigned NumResults = CountResults(Node);
 498     unsigned NodeOperands = CountOperands(Node);
 499     unsigned MemOperandsEnd = ComputeMemOperandsEnd(Node);
 500     bool HasPhysRegOuts = (NumResults > II.getNumDefs()) &&
 501                           II.getImplicitDefs() != 0;
 502 #ifndef NDEBUG
 503     unsigned NumMIOperands = NodeOperands + NumResults;
 504     assert((II.getNumOperands() == NumMIOperands ||
 505             HasPhysRegOuts || II.isVariadic()) &&
 506            "#operands for dag node doesn't match .td file!");
 507 #endif
 508
 509     // Create the new machine instruction.
 510     MachineInstr *MI = BuildMI(MF, Node->getDebugLoc(), II);
 511
 512     // Add result register values for things that are defined by this
 513     // instruction.
 514     if (NumResults)
 515       CreateVirtualRegisters(Node, MI, II, IsClone, IsCloned, VRBaseMap);
 516
 517     // Emit all of the actual operands of this instruction, adding them to the
 518     // instruction as appropriate.
 519     bool HasOptPRefs = II.getNumDefs() > NumResults;
 520     assert((!HasOptPRefs || !HasPhysRegOuts) &&
 521            "Unable to cope with optional defs and phys regs defs!");
 522     unsigned NumSkip = HasOptPRefs ? II.getNumDefs() - NumResults : 0;
 523     for (unsigned i = NumSkip; i != NodeOperands; ++i)
 524       AddOperand(MI, Node->getOperand(i), i-NumSkip+II.getNumDefs(), &II,
 525                  VRBaseMap);
 526
 527     // Emit all of the memory operands of this instruction
 528     for (unsigned i = NodeOperands; i != MemOperandsEnd; ++i)
 529       AddMemOperand(MI,cast<MemOperandSDNode>(Node->getOperand(i+NumSkip))->MO);
 530
 531     if (II.usesCustomDAGSchedInsertionHook()) {
 532       // Insert this instruction into the basic block using a target
 533       // specific inserter which may returns a new basic block.
 534       BB = TLI->EmitInstrWithCustomInserter(MI, BB);
 535       InsertPos = BB->end();
 536     } else {
 537       BB->insert(InsertPos, MI);
 538     }
 539
 540     // Additional results must be an physical register def.
 541     if (HasPhysRegOuts) {
 542       for (unsigned i = II.getNumDefs(); i < NumResults; ++i) {
 543         unsigned Reg = II.getImplicitDefs()[i - II.getNumDefs()];
 544         if (Node->hasAnyUseOfValue(i))
 545           EmitCopyFromReg(Node, i, IsClone, IsCloned, Reg, VRBaseMap);
 546       }
 547     }
 548     return;
 549   }
 550
 551   switch (Node->getOpcode()) {
 552   default:
 553 #ifndef NDEBUG
 554     Node->dump(DAG);
 555 #endif
 556     llvm_unreachable("This target-independent node should have been selected!");
 557     break;
 558   case ISD::EntryToken:
 559     llvm_unreachable("EntryToken should have been excluded from the schedule!");
 560     break;
 561   case ISD::MERGE_VALUES:
 562   case ISD::TokenFactor: // fall thru
 563     break;
 564   case ISD::CopyToReg: {
 565     unsigned SrcReg;
 566     SDValue SrcVal = Node->getOperand(2);
 567     if (RegisterSDNode *R = dyn_cast<RegisterSDNode>(SrcVal))
 568       SrcReg = R->getReg();
 569     else
 570       SrcReg = getVR(SrcVal, VRBaseMap);
 571
 572     unsigned DestReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
 573     if (SrcReg == DestReg) // Coalesced away the copy? Ignore.
 574       break;
 575
 576     const TargetRegisterClass *SrcTRC = 0, *DstTRC = 0;
 577     // Get the register classes of the src/dst.
 578     if (TargetRegisterInfo::isVirtualRegister(SrcReg))
 579       SrcTRC = MRI.getRegClass(SrcReg);
 580     else
 581       SrcTRC = TRI->getPhysicalRegisterRegClass(SrcReg,SrcVal.getValueType());
 582
 583     if (TargetRegisterInfo::isVirtualRegister(DestReg))
 584       DstTRC = MRI.getRegClass(DestReg);
 585     else
 586       DstTRC = TRI->getPhysicalRegisterRegClass(DestReg,
 587                                             Node->getOperand(1).getValueType());
 588
 589     bool Emitted = TII->copyRegToReg(*BB, InsertPos, DestReg, SrcReg,
 590                                      DstTRC, SrcTRC);
 591     assert(Emitted && "Unable to issue a copy instruction!\n");
 592     (void) Emitted;
 593     break;
 594   }
 595   case ISD::CopyFromReg: {
 596     unsigned SrcReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
 597     EmitCopyFromReg(Node, 0, IsClone, IsCloned, SrcReg, VRBaseMap);
 598     break;
 599   }
 600   case ISD::INLINEASM: {
 601     unsigned NumOps = Node->getNumOperands();
 602     if (Node->getOperand(NumOps-1).getValueType() == MVT::Flag)
 603       --NumOps;  // Ignore the flag operand.
 604
 605     // Create the inline asm machine instruction.
 606     MachineInstr *MI = BuildMI(MF, Node->getDebugLoc(),
 607                                TII->get(TargetInstrInfo::INLINEASM));
 608
 609     // Add the asm string as an external symbol operand.
 610     const char *AsmStr =
 611       cast<ExternalSymbolSDNode>(Node->getOperand(1))->getSymbol();
 612     MI->addOperand(MachineOperand::CreateES(AsmStr));
 613
 614     // Add all of the operand registers to the instruction.
 615     for (unsigned i = 2; i != NumOps;) {
 616       unsigned Flags =
 617         cast<ConstantSDNode>(Node->getOperand(i))->getZExtValue();
 618       unsigned NumVals = InlineAsm::getNumOperandRegisters(Flags);
 619
 620       MI->addOperand(MachineOperand::CreateImm(Flags));
 621       ++i;  // Skip the ID value.
 622
 623       switch (Flags & 7) {
 624       default: llvm_unreachable("Bad flags!");
 625       case 2:   // Def of register.
 626         for (; NumVals; --NumVals, ++i) {
 627           unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
 628           MI->addOperand(MachineOperand::CreateReg(Reg, true));
 629         }
 630         break;
 631       case 6:   // Def of earlyclobber register.
 632         for (; NumVals; --NumVals, ++i) {
 633           unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
 634           MI->addOperand(MachineOperand::CreateReg(Reg, true, false, false,
 635                                                    false, false, true));
 636         }
 637         break;
 638       case 1:  // Use of register.
 639       case 3:  // Immediate.
 640       case 4:  // Addressing mode.
 641         // The addressing mode has been selected, just add all of the
 642         // operands to the machine instruction.
 643         for (; NumVals; --NumVals, ++i)
 644           AddOperand(MI, Node->getOperand(i), 0, 0, VRBaseMap);
 645         break;
 646       }
 647     }
 648     BB->insert(InsertPos, MI);
 649     break;
 650   }
 651   }
 652 }
 653
 654 /// EmitSchedule - Emit the machine code in scheduled order.
 655 MachineBasicBlock *ScheduleDAGSDNodes::EmitSchedule() {
 656   DenseMap<SDValue, unsigned> VRBaseMap;
 657   DenseMap<SUnit*, unsigned> CopyVRBaseMap;
 658   for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
 659     SUnit *SU = Sequence[i];
 660     if (!SU) {
 661       // Null SUnit* is a noop.
 662       EmitNoop();
 663       continue;
 664     }
 665
 666     // For pre-regalloc scheduling, create instructions corresponding to the
 667     // SDNode and any flagged SDNodes and append them to the block.
 668     if (!SU->getNode()) {
 669       // Emit a copy.
 670       EmitPhysRegCopy(SU, CopyVRBaseMap);
 671       continue;
 672     }
 673
 674     SmallVector<SDNode *, 4> FlaggedNodes;
 675     for (SDNode *N = SU->getNode()->getFlaggedNode(); N;
 676          N = N->getFlaggedNode())
 677       FlaggedNodes.push_back(N);
 678     while (!FlaggedNodes.empty()) {
 679       EmitNode(FlaggedNodes.back(), SU->OrigNode != SU, SU->isCloned,VRBaseMap);
 680       FlaggedNodes.pop_back();
 681     }
 682     EmitNode(SU->getNode(), SU->OrigNode != SU, SU->isCloned, VRBaseMap);
 683   }
 684
 685   return BB;
 686 }