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