lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp

   1 //===-------- LegalizeTypesGeneric.cpp - Generic type legalization --------===//
   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 file implements generic type expansion and splitting for LegalizeTypes.
  11 // The routines here perform legalization when the details of the type (such as
  12 // whether it is an integer or a float) do not matter.
  13 // Expansion is the act of changing a computation in an illegal type to be a
  14 // computation in two identical registers of a smaller type.  The Lo/Hi part
  15 // is required to be stored first in memory on little/big-endian machines.
  16 // Splitting is the act of changing a computation in an illegal type to be a
  17 // computation in two not necessarily identical registers of a smaller type.
  18 // There are no requirements on how the type is represented in memory.
  19 //
  20 //===----------------------------------------------------------------------===//
  21
  22 #include "LegalizeTypes.h"
  23 #include "llvm/Target/TargetData.h"
  24 #include "llvm/CodeGen/PseudoSourceValue.h"
  25 using namespace llvm;
  26
  27 //===----------------------------------------------------------------------===//
  28 // Generic Result Expansion.
  29 //===----------------------------------------------------------------------===//
  30
  31 // These routines assume that the Lo/Hi part is stored first in memory on
  32 // little/big-endian machines, followed by the Hi/Lo part.  This means that
  33 // they cannot be used as is on vectors, for which Lo is always stored first.
  34
  35 void DAGTypeLegalizer::ExpandRes_BITCAST(SDNode *N, SDValue &Lo, SDValue &Hi) {
  36   EVT OutVT = N->getValueType(0);
  37   EVT NOutVT = TLI.getTypeToTransformTo(*DAG.getContext(), OutVT);
  38   SDValue InOp = N->getOperand(0);
  39   EVT InVT = InOp.getValueType();
  40   DebugLoc dl = N->getDebugLoc();
  41
  42   // Handle some special cases efficiently.
  43   switch (getTypeAction(InVT)) {
  44     default:
  45       assert(false && "Unknown type action!");
  46     case Legal:
  47     case PromoteInteger:
  48       break;
  49     case SoftenFloat:
  50       // Convert the integer operand instead.
  51       SplitInteger(GetSoftenedFloat(InOp), Lo, Hi);
  52       Lo = DAG.getNode(ISD::BITCAST, dl, NOutVT, Lo);
  53       Hi = DAG.getNode(ISD::BITCAST, dl, NOutVT, Hi);
  54       return;
  55     case ExpandInteger:
  56     case ExpandFloat:
  57       // Convert the expanded pieces of the input.
  58       GetExpandedOp(InOp, Lo, Hi);
  59       Lo = DAG.getNode(ISD::BITCAST, dl, NOutVT, Lo);
  60       Hi = DAG.getNode(ISD::BITCAST, dl, NOutVT, Hi);
  61       return;
  62     case SplitVector:
  63       GetSplitVector(InOp, Lo, Hi);
  64       if (TLI.isBigEndian())
  65         std::swap(Lo, Hi);
  66       Lo = DAG.getNode(ISD::BITCAST, dl, NOutVT, Lo);
  67       Hi = DAG.getNode(ISD::BITCAST, dl, NOutVT, Hi);
  68       return;
  69     case ScalarizeVector:
  70       // Convert the element instead.
  71       SplitInteger(BitConvertToInteger(GetScalarizedVector(InOp)), Lo, Hi);
  72       Lo = DAG.getNode(ISD::BITCAST, dl, NOutVT, Lo);
  73       Hi = DAG.getNode(ISD::BITCAST, dl, NOutVT, Hi);
  74       return;
  75     case WidenVector: {
  76       assert(!(InVT.getVectorNumElements() & 1) && "Unsupported BITCAST");
  77       InOp = GetWidenedVector(InOp);
  78       EVT InNVT = EVT::getVectorVT(*DAG.getContext(), InVT.getVectorElementType(),
  79                                    InVT.getVectorNumElements()/2);
  80       Lo = DAG.getNode(ISD::EXTRACT_SUBVECTOR, dl, InNVT, InOp,
  81                        DAG.getIntPtrConstant(0));
  82       Hi = DAG.getNode(ISD::EXTRACT_SUBVECTOR, dl, InNVT, InOp,
  83                        DAG.getIntPtrConstant(InNVT.getVectorNumElements()));
  84       if (TLI.isBigEndian())
  85         std::swap(Lo, Hi);
  86       Lo = DAG.getNode(ISD::BITCAST, dl, NOutVT, Lo);
  87       Hi = DAG.getNode(ISD::BITCAST, dl, NOutVT, Hi);
  88       return;
  89     }
  90   }
  91
  92   if (InVT.isVector() && OutVT.isInteger()) {
  93     // Handle cases like i64 = BITCAST v1i64 on x86, where the operand
  94     // is legal but the result is not.
  95     EVT NVT = EVT::getVectorVT(*DAG.getContext(), NOutVT, 2);
  96
  97     if (isTypeLegal(NVT)) {
  98       SDValue CastInOp = DAG.getNode(ISD::BITCAST, dl, NVT, InOp);
  99       Lo = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, NOutVT, CastInOp,
 100                        DAG.getIntPtrConstant(0));
 101       Hi = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, NOutVT, CastInOp,
 102                        DAG.getIntPtrConstant(1));
 103
 104       if (TLI.isBigEndian())
 105         std::swap(Lo, Hi);
 106
 107       return;
 108     }
 109   }
 110
 111   // Lower the bit-convert to a store/load from the stack.
 112   assert(NOutVT.isByteSized() && "Expanded type not byte sized!");
 113
 114   // Create the stack frame object.  Make sure it is aligned for both
 115   // the source and expanded destination types.
 116   unsigned Alignment =
 117     TLI.getTargetData()->getPrefTypeAlignment(NOutVT.
 118                                               getTypeForEVT(*DAG.getContext()));
 119   SDValue StackPtr = DAG.CreateStackTemporary(InVT, Alignment);
 120   int SPFI = cast<FrameIndexSDNode>(StackPtr.getNode())->getIndex();
 121   MachinePointerInfo PtrInfo = MachinePointerInfo::getFixedStack(SPFI);
 122
 123   // Emit a store to the stack slot.
 124   SDValue Store = DAG.getStore(DAG.getEntryNode(), dl, InOp, StackPtr, PtrInfo,
 125                                false, false, 0);
 126
 127   // Load the first half from the stack slot.
 128   Lo = DAG.getLoad(NOutVT, dl, Store, StackPtr, PtrInfo, false, false, 0);
 129
 130   // Increment the pointer to the other half.
 131   unsigned IncrementSize = NOutVT.getSizeInBits() / 8;
 132   StackPtr = DAG.getNode(ISD::ADD, dl, StackPtr.getValueType(), StackPtr,
 133                          DAG.getIntPtrConstant(IncrementSize));
 134
 135   // Load the second half from the stack slot.
 136   Hi = DAG.getLoad(NOutVT, dl, Store, StackPtr,
 137                    PtrInfo.getWithOffset(IncrementSize), false,
 138                    false, MinAlign(Alignment, IncrementSize));
 139
 140   // Handle endianness of the load.
 141   if (TLI.isBigEndian())
 142     std::swap(Lo, Hi);
 143 }
 144
 145 void DAGTypeLegalizer::ExpandRes_BUILD_PAIR(SDNode *N, SDValue &Lo,
 146                                             SDValue &Hi) {
 147   // Return the operands.
 148   Lo = N->getOperand(0);
 149   Hi = N->getOperand(1);
 150 }
 151
 152 void DAGTypeLegalizer::ExpandRes_EXTRACT_ELEMENT(SDNode *N, SDValue &Lo,
 153                                                  SDValue &Hi) {
 154   GetExpandedOp(N->getOperand(0), Lo, Hi);
 155   SDValue Part = cast<ConstantSDNode>(N->getOperand(1))->getZExtValue() ?
 156                    Hi : Lo;
 157
 158   assert(Part.getValueType() == N->getValueType(0) &&
 159          "Type twice as big as expanded type not itself expanded!");
 160
 161   GetPairElements(Part, Lo, Hi);
 162 }
 163
 164 void DAGTypeLegalizer::ExpandRes_EXTRACT_VECTOR_ELT(SDNode *N, SDValue &Lo,
 165                                                     SDValue &Hi) {
 166   SDValue OldVec = N->getOperand(0);
 167   unsigned OldElts = OldVec.getValueType().getVectorNumElements();
 168   DebugLoc dl = N->getDebugLoc();
 169
 170   // Convert to a vector of the expanded element type, for example
 171   // <3 x i64> -> <6 x i32>.
 172   EVT OldVT = N->getValueType(0);
 173   EVT NewVT = TLI.getTypeToTransformTo(*DAG.getContext(), OldVT);
 174
 175   SDValue NewVec = DAG.getNode(ISD::BITCAST, dl,
 176                                EVT::getVectorVT(*DAG.getContext(),
 177                                                 NewVT, 2*OldElts),
 178                                OldVec);
 179
 180   // Extract the elements at 2 * Idx and 2 * Idx + 1 from the new vector.
 181   SDValue Idx = N->getOperand(1);
 182
 183   // Make sure the type of Idx is big enough to hold the new values.
 184   if (Idx.getValueType().bitsLT(TLI.getPointerTy()))
 185     Idx = DAG.getNode(ISD::ZERO_EXTEND, dl, TLI.getPointerTy(), Idx);
 186
 187   Idx = DAG.getNode(ISD::ADD, dl, Idx.getValueType(), Idx, Idx);
 188   Lo = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, NewVT, NewVec, Idx);
 189
 190   Idx = DAG.getNode(ISD::ADD, dl, Idx.getValueType(), Idx,
 191                     DAG.getConstant(1, Idx.getValueType()));
 192   Hi = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, NewVT, NewVec, Idx);
 193
 194   if (TLI.isBigEndian())
 195     std::swap(Lo, Hi);
 196 }
 197
 198 void DAGTypeLegalizer::ExpandRes_NormalLoad(SDNode *N, SDValue &Lo,
 199                                             SDValue &Hi) {
 200   assert(ISD::isNormalLoad(N) && "This routine only for normal loads!");
 201   DebugLoc dl = N->getDebugLoc();
 202
 203   LoadSDNode *LD = cast<LoadSDNode>(N);
 204   EVT NVT = TLI.getTypeToTransformTo(*DAG.getContext(), LD->getValueType(0));
 205   SDValue Chain = LD->getChain();
 206   SDValue Ptr = LD->getBasePtr();
 207   unsigned Alignment = LD->getAlignment();
 208   bool isVolatile = LD->isVolatile();
 209   bool isNonTemporal = LD->isNonTemporal();
 210
 211   assert(NVT.isByteSized() && "Expanded type not byte sized!");
 212
 213   Lo = DAG.getLoad(NVT, dl, Chain, Ptr, LD->getPointerInfo(),
 214                    isVolatile, isNonTemporal, Alignment);
 215
 216   // Increment the pointer to the other half.
 217   unsigned IncrementSize = NVT.getSizeInBits() / 8;
 218   Ptr = DAG.getNode(ISD::ADD, dl, Ptr.getValueType(), Ptr,
 219                     DAG.getIntPtrConstant(IncrementSize));
 220   Hi = DAG.getLoad(NVT, dl, Chain, Ptr,
 221                    LD->getPointerInfo().getWithOffset(IncrementSize),
 222                    isVolatile, isNonTemporal,
 223                    MinAlign(Alignment, IncrementSize));
 224
 225   // Build a factor node to remember that this load is independent of the
 226   // other one.
 227   Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Lo.getValue(1),
 228                       Hi.getValue(1));
 229
 230   // Handle endianness of the load.
 231   if (TLI.isBigEndian())
 232     std::swap(Lo, Hi);
 233
 234   // Modified the chain - switch anything that used the old chain to use
 235   // the new one.
 236   ReplaceValueWith(SDValue(N, 1), Chain);
 237 }
 238
 239 void DAGTypeLegalizer::ExpandRes_VAARG(SDNode *N, SDValue &Lo, SDValue &Hi) {
 240   EVT OVT = N->getValueType(0);
 241   EVT NVT = TLI.getTypeToTransformTo(*DAG.getContext(), OVT);
 242   SDValue Chain = N->getOperand(0);
 243   SDValue Ptr = N->getOperand(1);
 244   DebugLoc dl = N->getDebugLoc();
 245   const unsigned Align = N->getConstantOperandVal(3);
 246
 247   Lo = DAG.getVAArg(NVT, dl, Chain, Ptr, N->getOperand(2), Align);
 248   Hi = DAG.getVAArg(NVT, dl, Lo.getValue(1), Ptr, N->getOperand(2), 0);
 249
 250   // Handle endianness of the load.
 251   if (TLI.isBigEndian())
 252     std::swap(Lo, Hi);
 253
 254   // Modified the chain - switch anything that used the old chain to use
 255   // the new one.
 256   ReplaceValueWith(SDValue(N, 1), Hi.getValue(1));
 257 }
 258
 259
 260 //===--------------------------------------------------------------------===//
 261 // Generic Operand Expansion.
 262 //===--------------------------------------------------------------------===//
 263
 264 SDValue DAGTypeLegalizer::ExpandOp_BITCAST(SDNode *N) {
 265   DebugLoc dl = N->getDebugLoc();
 266   if (N->getValueType(0).isVector()) {
 267     // An illegal expanding type is being converted to a legal vector type.
 268     // Make a two element vector out of the expanded parts and convert that
 269     // instead, but only if the new vector type is legal (otherwise there
 270     // is no point, and it might create expansion loops).  For example, on
 271     // x86 this turns v1i64 = BITCAST i64 into v1i64 = BITCAST v2i32.
 272     EVT OVT = N->getOperand(0).getValueType();
 273     EVT NVT = EVT::getVectorVT(*DAG.getContext(),
 274                                TLI.getTypeToTransformTo(*DAG.getContext(), OVT),
 275                                2);
 276
 277     if (isTypeLegal(NVT)) {
 278       SDValue Parts[2];
 279       GetExpandedOp(N->getOperand(0), Parts[0], Parts[1]);
 280
 281       if (TLI.isBigEndian())
 282         std::swap(Parts[0], Parts[1]);
 283
 284       SDValue Vec = DAG.getNode(ISD::BUILD_VECTOR, dl, NVT, Parts, 2);
 285       return DAG.getNode(ISD::BITCAST, dl, N->getValueType(0), Vec);
 286     }
 287   }
 288
 289   // Otherwise, store to a temporary and load out again as the new type.
 290   return CreateStackStoreLoad(N->getOperand(0), N->getValueType(0));
 291 }
 292
 293 SDValue DAGTypeLegalizer::ExpandOp_BUILD_VECTOR(SDNode *N) {
 294   // The vector type is legal but the element type needs expansion.
 295   EVT VecVT = N->getValueType(0);
 296   unsigned NumElts = VecVT.getVectorNumElements();
 297   EVT OldVT = N->getOperand(0).getValueType();
 298   EVT NewVT = TLI.getTypeToTransformTo(*DAG.getContext(), OldVT);
 299   DebugLoc dl = N->getDebugLoc();
 300
 301   assert(OldVT == VecVT.getVectorElementType() &&
 302          "BUILD_VECTOR operand type doesn't match vector element type!");
 303
 304   // Build a vector of twice the length out of the expanded elements.
 305   // For example <3 x i64> -> <6 x i32>.
 306   std::vector<SDValue> NewElts;
 307   NewElts.reserve(NumElts*2);
 308
 309   for (unsigned i = 0; i < NumElts; ++i) {
 310     SDValue Lo, Hi;
 311     GetExpandedOp(N->getOperand(i), Lo, Hi);
 312     if (TLI.isBigEndian())
 313       std::swap(Lo, Hi);
 314     NewElts.push_back(Lo);
 315     NewElts.push_back(Hi);
 316   }
 317
 318   SDValue NewVec = DAG.getNode(ISD::BUILD_VECTOR, dl,
 319                                EVT::getVectorVT(*DAG.getContext(),
 320                                                 NewVT, NewElts.size()),
 321                                &NewElts[0], NewElts.size());
 322
 323   // Convert the new vector to the old vector type.
 324   return DAG.getNode(ISD::BITCAST, dl, VecVT, NewVec);
 325 }
 326
 327 SDValue DAGTypeLegalizer::ExpandOp_EXTRACT_ELEMENT(SDNode *N) {
 328   SDValue Lo, Hi;
 329   GetExpandedOp(N->getOperand(0), Lo, Hi);
 330   return cast<ConstantSDNode>(N->getOperand(1))->getZExtValue() ? Hi : Lo;
 331 }
 332
 333 SDValue DAGTypeLegalizer::ExpandOp_INSERT_VECTOR_ELT(SDNode *N) {
 334   // The vector type is legal but the element type needs expansion.
 335   EVT VecVT = N->getValueType(0);
 336   unsigned NumElts = VecVT.getVectorNumElements();
 337   DebugLoc dl = N->getDebugLoc();
 338
 339   SDValue Val = N->getOperand(1);
 340   EVT OldEVT = Val.getValueType();
 341   EVT NewEVT = TLI.getTypeToTransformTo(*DAG.getContext(), OldEVT);
 342
 343   assert(OldEVT == VecVT.getVectorElementType() &&
 344          "Inserted element type doesn't match vector element type!");
 345
 346   // Bitconvert to a vector of twice the length with elements of the expanded
 347   // type, insert the expanded vector elements, and then convert back.
 348   EVT NewVecVT = EVT::getVectorVT(*DAG.getContext(), NewEVT, NumElts*2);
 349   SDValue NewVec = DAG.getNode(ISD::BITCAST, dl,
 350                                NewVecVT, N->getOperand(0));
 351
 352   SDValue Lo, Hi;
 353   GetExpandedOp(Val, Lo, Hi);
 354   if (TLI.isBigEndian())
 355     std::swap(Lo, Hi);
 356
 357   SDValue Idx = N->getOperand(2);
 358   Idx = DAG.getNode(ISD::ADD, dl, Idx.getValueType(), Idx, Idx);
 359   NewVec = DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, NewVecVT, NewVec, Lo, Idx);
 360   Idx = DAG.getNode(ISD::ADD, dl,
 361                     Idx.getValueType(), Idx, DAG.getIntPtrConstant(1));
 362   NewVec =  DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, NewVecVT, NewVec, Hi, Idx);
 363
 364   // Convert the new vector to the old vector type.
 365   return DAG.getNode(ISD::BITCAST, dl, VecVT, NewVec);
 366 }
 367
 368 SDValue DAGTypeLegalizer::ExpandOp_SCALAR_TO_VECTOR(SDNode *N) {
 369   DebugLoc dl = N->getDebugLoc();
 370   EVT VT = N->getValueType(0);
 371   assert(VT.getVectorElementType() == N->getOperand(0).getValueType() &&
 372          "SCALAR_TO_VECTOR operand type doesn't match vector element type!");
 373   unsigned NumElts = VT.getVectorNumElements();
 374   SmallVector<SDValue, 16> Ops(NumElts);
 375   Ops[0] = N->getOperand(0);
 376   SDValue UndefVal = DAG.getUNDEF(Ops[0].getValueType());
 377   for (unsigned i = 1; i < NumElts; ++i)
 378     Ops[i] = UndefVal;
 379   return DAG.getNode(ISD::BUILD_VECTOR, dl, VT, &Ops[0], NumElts);
 380 }
 381
 382 SDValue DAGTypeLegalizer::ExpandOp_NormalStore(SDNode *N, unsigned OpNo) {
 383   assert(ISD::isNormalStore(N) && "This routine only for normal stores!");
 384   assert(OpNo == 1 && "Can only expand the stored value so far");
 385   DebugLoc dl = N->getDebugLoc();
 386
 387   StoreSDNode *St = cast<StoreSDNode>(N);
 388   EVT NVT = TLI.getTypeToTransformTo(*DAG.getContext(),
 389                                      St->getValue().getValueType());
 390   SDValue Chain = St->getChain();
 391   SDValue Ptr = St->getBasePtr();
 392   unsigned Alignment = St->getAlignment();
 393   bool isVolatile = St->isVolatile();
 394   bool isNonTemporal = St->isNonTemporal();
 395
 396   assert(NVT.isByteSized() && "Expanded type not byte sized!");
 397   unsigned IncrementSize = NVT.getSizeInBits() / 8;
 398
 399   SDValue Lo, Hi;
 400   GetExpandedOp(St->getValue(), Lo, Hi);
 401
 402   if (TLI.isBigEndian())
 403     std::swap(Lo, Hi);
 404
 405   Lo = DAG.getStore(Chain, dl, Lo, Ptr, St->getPointerInfo(),
 406                     isVolatile, isNonTemporal, Alignment);
 407
 408   Ptr = DAG.getNode(ISD::ADD, dl, Ptr.getValueType(), Ptr,
 409                     DAG.getIntPtrConstant(IncrementSize));
 410   assert(isTypeLegal(Ptr.getValueType()) && "Pointers must be legal!");
 411   Hi = DAG.getStore(Chain, dl, Hi, Ptr,
 412                     St->getPointerInfo().getWithOffset(IncrementSize),
 413                     isVolatile, isNonTemporal,
 414                     MinAlign(Alignment, IncrementSize));
 415
 416   return DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Lo, Hi);
 417 }
 418
 419
 420 //===--------------------------------------------------------------------===//
 421 // Generic Result Splitting.
 422 //===--------------------------------------------------------------------===//
 423
 424 // Be careful to make no assumptions about which of Lo/Hi is stored first in
 425 // memory (for vectors it is always Lo first followed by Hi in the following
 426 // bytes; for integers and floats it is Lo first if and only if the machine is
 427 // little-endian).
 428
 429 void DAGTypeLegalizer::SplitRes_MERGE_VALUES(SDNode *N,
 430                                              SDValue &Lo, SDValue &Hi) {
 431   // A MERGE_VALUES node can produce any number of values.  We know that the
 432   // first illegal one needs to be expanded into Lo/Hi.
 433   unsigned i;
 434
 435   // The string of legal results gets turned into input operands, which have
 436   // the same type.
 437   for (i = 0; isTypeLegal(N->getValueType(i)); ++i)
 438     ReplaceValueWith(SDValue(N, i), SDValue(N->getOperand(i)));
 439
 440   // The first illegal result must be the one that needs to be expanded.
 441   GetSplitOp(N->getOperand(i), Lo, Hi);
 442
 443   // Legalize the rest of the results into the input operands whether they are
 444   // legal or not.
 445   unsigned e = N->getNumValues();
 446   for (++i; i != e; ++i)
 447     ReplaceValueWith(SDValue(N, i), SDValue(N->getOperand(i)));
 448 }
 449
 450 void DAGTypeLegalizer::SplitRes_SELECT(SDNode *N, SDValue &Lo,
 451                                        SDValue &Hi) {
 452   SDValue LL, LH, RL, RH;
 453   DebugLoc dl = N->getDebugLoc();
 454   GetSplitOp(N->getOperand(1), LL, LH);
 455   GetSplitOp(N->getOperand(2), RL, RH);
 456
 457   SDValue Cond = N->getOperand(0);
 458   Lo = DAG.getNode(ISD::SELECT, dl, LL.getValueType(), Cond, LL, RL);
 459   Hi = DAG.getNode(ISD::SELECT, dl, LH.getValueType(), Cond, LH, RH);
 460 }
 461
 462 void DAGTypeLegalizer::SplitRes_SELECT_CC(SDNode *N, SDValue &Lo,
 463                                           SDValue &Hi) {
 464   SDValue LL, LH, RL, RH;
 465   DebugLoc dl = N->getDebugLoc();
 466   GetSplitOp(N->getOperand(2), LL, LH);
 467   GetSplitOp(N->getOperand(3), RL, RH);
 468
 469   Lo = DAG.getNode(ISD::SELECT_CC, dl, LL.getValueType(), N->getOperand(0),
 470                    N->getOperand(1), LL, RL, N->getOperand(4));
 471   Hi = DAG.getNode(ISD::SELECT_CC, dl, LH.getValueType(), N->getOperand(0),
 472                    N->getOperand(1), LH, RH, N->getOperand(4));
 473 }
 474
 475 void DAGTypeLegalizer::SplitRes_UNDEF(SDNode *N, SDValue &Lo, SDValue &Hi) {
 476   EVT LoVT, HiVT;
 477   GetSplitDestVTs(N->getValueType(0), LoVT, HiVT);
 478   Lo = DAG.getUNDEF(LoVT);
 479   Hi = DAG.getUNDEF(HiVT);
 480 }