lib/VMCore/Constants.cpp

   1 //===-- Constants.cpp - Implement Constant nodes --------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the Constant* classes...
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Constants.h"
  15 #include "ConstantFolding.h"
  16 #include "llvm/DerivedTypes.h"
  17 #include "llvm/GlobalValue.h"
  18 #include "llvm/Instructions.h"
  19 #include "llvm/SymbolTable.h"
  20 #include "llvm/Module.h"
  21 #include "llvm/ADT/StringExtras.h"
  22 #include "llvm/Support/MathExtras.h"
  23 #include "llvm/Support/Visibility.h"
  24 #include <algorithm>
  25 #include <iostream>
  26 using namespace llvm;
  27
  28 ConstantBool *ConstantBool::True  = new ConstantBool(true);
  29 ConstantBool *ConstantBool::False = new ConstantBool(false);
  30
  31
  32 //===----------------------------------------------------------------------===//
  33 //                              Constant Class
  34 //===----------------------------------------------------------------------===//
  35
  36 void Constant::destroyConstantImpl() {
  37   // When a Constant is destroyed, there may be lingering
  38   // references to the constant by other constants in the constant pool.  These
  39   // constants are implicitly dependent on the module that is being deleted,
  40   // but they don't know that.  Because we only find out when the CPV is
  41   // deleted, we must now notify all of our users (that should only be
  42   // Constants) that they are, in fact, invalid now and should be deleted.
  43   //
  44   while (!use_empty()) {
  45     Value *V = use_back();
  46 #ifndef NDEBUG      // Only in -g mode...
  47     if (!isa<Constant>(V))
  48       std::cerr << "While deleting: " << *this
  49                 << "\n\nUse still stuck around after Def is destroyed: "
  50                 << *V << "\n\n";
  51 #endif
  52     assert(isa<Constant>(V) && "References remain to Constant being destroyed");
  53     Constant *CV = cast<Constant>(V);
  54     CV->destroyConstant();
  55
  56     // The constant should remove itself from our use list...
  57     assert((use_empty() || use_back() != V) && "Constant not removed!");
  58   }
  59
  60   // Value has no outstanding references it is safe to delete it now...
  61   delete this;
  62 }
  63
  64 // Static constructor to create a '0' constant of arbitrary type...
  65 Constant *Constant::getNullValue(const Type *Ty) {
  66   switch (Ty->getTypeID()) {
  67   case Type::BoolTyID: {
  68     static Constant *NullBool = ConstantBool::get(false);
  69     return NullBool;
  70   }
  71   case Type::SByteTyID: {
  72     static Constant *NullSByte = ConstantSInt::get(Type::SByteTy, 0);
  73     return NullSByte;
  74   }
  75   case Type::UByteTyID: {
  76     static Constant *NullUByte = ConstantUInt::get(Type::UByteTy, 0);
  77     return NullUByte;
  78   }
  79   case Type::ShortTyID: {
  80     static Constant *NullShort = ConstantSInt::get(Type::ShortTy, 0);
  81     return NullShort;
  82   }
  83   case Type::UShortTyID: {
  84     static Constant *NullUShort = ConstantUInt::get(Type::UShortTy, 0);
  85     return NullUShort;
  86   }
  87   case Type::IntTyID: {
  88     static Constant *NullInt = ConstantSInt::get(Type::IntTy, 0);
  89     return NullInt;
  90   }
  91   case Type::UIntTyID: {
  92     static Constant *NullUInt = ConstantUInt::get(Type::UIntTy, 0);
  93     return NullUInt;
  94   }
  95   case Type::LongTyID: {
  96     static Constant *NullLong = ConstantSInt::get(Type::LongTy, 0);
  97     return NullLong;
  98   }
  99   case Type::ULongTyID: {
 100     static Constant *NullULong = ConstantUInt::get(Type::ULongTy, 0);
 101     return NullULong;
 102   }
 103
 104   case Type::FloatTyID: {
 105     static Constant *NullFloat = ConstantFP::get(Type::FloatTy, 0);
 106     return NullFloat;
 107   }
 108   case Type::DoubleTyID: {
 109     static Constant *NullDouble = ConstantFP::get(Type::DoubleTy, 0);
 110     return NullDouble;
 111   }
 112
 113   case Type::PointerTyID:
 114     return ConstantPointerNull::get(cast<PointerType>(Ty));
 115
 116   case Type::StructTyID:
 117   case Type::ArrayTyID:
 118   case Type::PackedTyID:
 119     return ConstantAggregateZero::get(Ty);
 120   default:
 121     // Function, Label, or Opaque type?
 122     assert(!"Cannot create a null constant of that type!");
 123     return 0;
 124   }
 125 }
 126
 127 // Static constructor to create the maximum constant of an integral type...
 128 ConstantIntegral *ConstantIntegral::getMaxValue(const Type *Ty) {
 129   switch (Ty->getTypeID()) {
 130   case Type::BoolTyID:   return ConstantBool::True;
 131   case Type::SByteTyID:
 132   case Type::ShortTyID:
 133   case Type::IntTyID:
 134   case Type::LongTyID: {
 135     // Calculate 011111111111111...
 136     unsigned TypeBits = Ty->getPrimitiveSize()*8;
 137     int64_t Val = INT64_MAX;             // All ones
 138     Val >>= 64-TypeBits;                 // Shift out unwanted 1 bits...
 139     return ConstantSInt::get(Ty, Val);
 140   }
 141
 142   case Type::UByteTyID:
 143   case Type::UShortTyID:
 144   case Type::UIntTyID:
 145   case Type::ULongTyID:  return getAllOnesValue(Ty);
 146
 147   default: return 0;
 148   }
 149 }
 150
 151 // Static constructor to create the minimum constant for an integral type...
 152 ConstantIntegral *ConstantIntegral::getMinValue(const Type *Ty) {
 153   switch (Ty->getTypeID()) {
 154   case Type::BoolTyID:   return ConstantBool::False;
 155   case Type::SByteTyID:
 156   case Type::ShortTyID:
 157   case Type::IntTyID:
 158   case Type::LongTyID: {
 159      // Calculate 1111111111000000000000
 160      unsigned TypeBits = Ty->getPrimitiveSize()*8;
 161      int64_t Val = -1;                    // All ones
 162      Val <<= TypeBits-1;                  // Shift over to the right spot
 163      return ConstantSInt::get(Ty, Val);
 164   }
 165
 166   case Type::UByteTyID:
 167   case Type::UShortTyID:
 168   case Type::UIntTyID:
 169   case Type::ULongTyID:  return ConstantUInt::get(Ty, 0);
 170
 171   default: return 0;
 172   }
 173 }
 174
 175 // Static constructor to create an integral constant with all bits set
 176 ConstantIntegral *ConstantIntegral::getAllOnesValue(const Type *Ty) {
 177   switch (Ty->getTypeID()) {
 178   case Type::BoolTyID:   return ConstantBool::True;
 179   case Type::SByteTyID:
 180   case Type::ShortTyID:
 181   case Type::IntTyID:
 182   case Type::LongTyID:   return ConstantSInt::get(Ty, -1);
 183
 184   case Type::UByteTyID:
 185   case Type::UShortTyID:
 186   case Type::UIntTyID:
 187   case Type::ULongTyID: {
 188     // Calculate ~0 of the right type...
 189     unsigned TypeBits = Ty->getPrimitiveSize()*8;
 190     uint64_t Val = ~0ULL;                // All ones
 191     Val >>= 64-TypeBits;                 // Shift out unwanted 1 bits...
 192     return ConstantUInt::get(Ty, Val);
 193   }
 194   default: return 0;
 195   }
 196 }
 197
 198 bool ConstantUInt::isAllOnesValue() const {
 199   unsigned TypeBits = getType()->getPrimitiveSize()*8;
 200   uint64_t Val = ~0ULL;                // All ones
 201   Val >>= 64-TypeBits;                 // Shift out inappropriate bits
 202   return getValue() == Val;
 203 }
 204
 205
 206 //===----------------------------------------------------------------------===//
 207 //                            ConstantXXX Classes
 208 //===----------------------------------------------------------------------===//
 209
 210 //===----------------------------------------------------------------------===//
 211 //                             Normal Constructors
 212
 213 ConstantIntegral::ConstantIntegral(const Type *Ty, ValueTy VT, uint64_t V)
 214   : Constant(Ty, VT, 0, 0) {
 215     Val.Unsigned = V;
 216 }
 217
 218 ConstantBool::ConstantBool(bool V)
 219   : ConstantIntegral(Type::BoolTy, ConstantBoolVal, V) {
 220 }
 221
 222 ConstantInt::ConstantInt(const Type *Ty, ValueTy VT, uint64_t V)
 223   : ConstantIntegral(Ty, VT, V) {
 224 }
 225
 226 ConstantSInt::ConstantSInt(const Type *Ty, int64_t V)
 227   : ConstantInt(Ty, ConstantSIntVal, V) {
 228   assert(Ty->isInteger() && Ty->isSigned() &&
 229          "Illegal type for signed integer constant!");
 230   assert(isValueValidForType(Ty, V) && "Value too large for type!");
 231 }
 232
 233 ConstantUInt::ConstantUInt(const Type *Ty, uint64_t V)
 234   : ConstantInt(Ty, ConstantUIntVal, V) {
 235   assert(Ty->isInteger() && Ty->isUnsigned() &&
 236          "Illegal type for unsigned integer constant!");
 237   assert(isValueValidForType(Ty, V) && "Value too large for type!");
 238 }
 239
 240 ConstantFP::ConstantFP(const Type *Ty, double V)
 241   : Constant(Ty, ConstantFPVal, 0, 0) {
 242   assert(isValueValidForType(Ty, V) && "Value too large for type!");
 243   Val = V;
 244 }
 245
 246 ConstantArray::ConstantArray(const ArrayType *T,
 247                              const std::vector<Constant*> &V)
 248   : Constant(T, ConstantArrayVal, new Use[V.size()], V.size()) {
 249   assert(V.size() == T->getNumElements() &&
 250          "Invalid initializer vector for constant array");
 251   Use *OL = OperandList;
 252   for (std::vector<Constant*>::const_iterator I = V.begin(), E = V.end();
 253        I != E; ++I, ++OL) {
 254     Constant *C = *I;
 255     assert((C->getType() == T->getElementType() ||
 256             (T->isAbstract() &&
 257              C->getType()->getTypeID() == T->getElementType()->getTypeID())) &&
 258            "Initializer for array element doesn't match array element type!");
 259     OL->init(C, this);
 260   }
 261 }
 262
 263 ConstantArray::~ConstantArray() {
 264   delete [] OperandList;
 265 }
 266
 267 ConstantStruct::ConstantStruct(const StructType *T,
 268                                const std::vector<Constant*> &V)
 269   : Constant(T, ConstantStructVal, new Use[V.size()], V.size()) {
 270   assert(V.size() == T->getNumElements() &&
 271          "Invalid initializer vector for constant structure");
 272   Use *OL = OperandList;
 273   for (std::vector<Constant*>::const_iterator I = V.begin(), E = V.end();
 274        I != E; ++I, ++OL) {
 275     Constant *C = *I;
 276     assert((C->getType() == T->getElementType(I-V.begin()) ||
 277             ((T->getElementType(I-V.begin())->isAbstract() ||
 278               C->getType()->isAbstract()) &&
 279              T->getElementType(I-V.begin())->getTypeID() ==
 280                    C->getType()->getTypeID())) &&
 281            "Initializer for struct element doesn't match struct element type!");
 282     OL->init(C, this);
 283   }
 284 }
 285
 286 ConstantStruct::~ConstantStruct() {
 287   delete [] OperandList;
 288 }
 289
 290
 291 ConstantPacked::ConstantPacked(const PackedType *T,
 292                                const std::vector<Constant*> &V)
 293   : Constant(T, ConstantPackedVal, new Use[V.size()], V.size()) {
 294   Use *OL = OperandList;
 295     for (std::vector<Constant*>::const_iterator I = V.begin(), E = V.end();
 296          I != E; ++I, ++OL) {
 297       Constant *C = *I;
 298       assert((C->getType() == T->getElementType() ||
 299             (T->isAbstract() &&
 300              C->getType()->getTypeID() == T->getElementType()->getTypeID())) &&
 301            "Initializer for packed element doesn't match packed element type!");
 302     OL->init(C, this);
 303   }
 304 }
 305
 306 ConstantPacked::~ConstantPacked() {
 307   delete [] OperandList;
 308 }
 309
 310 /// UnaryConstantExpr - This class is private to Constants.cpp, and is used
 311 /// behind the scenes to implement unary constant exprs.
 312 namespace {
 313 class VISIBILITY_HIDDEN UnaryConstantExpr : public ConstantExpr {
 314   Use Op;
 315 public:
 316   UnaryConstantExpr(unsigned Opcode, Constant *C, const Type *Ty)
 317     : ConstantExpr(Ty, Opcode, &Op, 1), Op(C, this) {}
 318 };
 319 }
 320
 321 static bool isSetCC(unsigned Opcode) {
 322   return Opcode == Instruction::SetEQ || Opcode == Instruction::SetNE ||
 323          Opcode == Instruction::SetLT || Opcode == Instruction::SetGT ||
 324          Opcode == Instruction::SetLE || Opcode == Instruction::SetGE;
 325 }
 326
 327 /// BinaryConstantExpr - This class is private to Constants.cpp, and is used
 328 /// behind the scenes to implement binary constant exprs.
 329 namespace {
 330 class VISIBILITY_HIDDEN BinaryConstantExpr : public ConstantExpr {
 331   Use Ops[2];
 332 public:
 333   BinaryConstantExpr(unsigned Opcode, Constant *C1, Constant *C2)
 334     : ConstantExpr(isSetCC(Opcode) ? Type::BoolTy : C1->getType(),
 335                    Opcode, Ops, 2) {
 336     Ops[0].init(C1, this);
 337     Ops[1].init(C2, this);
 338   }
 339 };
 340 }
 341
 342 /// SelectConstantExpr - This class is private to Constants.cpp, and is used
 343 /// behind the scenes to implement select constant exprs.
 344 namespace {
 345 class VISIBILITY_HIDDEN SelectConstantExpr : public ConstantExpr {
 346   Use Ops[3];
 347 public:
 348   SelectConstantExpr(Constant *C1, Constant *C2, Constant *C3)
 349     : ConstantExpr(C2->getType(), Instruction::Select, Ops, 3) {
 350     Ops[0].init(C1, this);
 351     Ops[1].init(C2, this);
 352     Ops[2].init(C3, this);
 353   }
 354 };
 355 }
 356
 357 /// ExtractElementConstantExpr - This class is private to
 358 /// Constants.cpp, and is used behind the scenes to implement
 359 /// extractelement constant exprs.
 360 namespace {
 361 class VISIBILITY_HIDDEN ExtractElementConstantExpr : public ConstantExpr {
 362   Use Ops[2];
 363 public:
 364   ExtractElementConstantExpr(Constant *C1, Constant *C2)
 365     : ConstantExpr(cast<PackedType>(C1->getType())->getElementType(),
 366                    Instruction::ExtractElement, Ops, 2) {
 367     Ops[0].init(C1, this);
 368     Ops[1].init(C2, this);
 369   }
 370 };
 371 }
 372
 373 /// InsertElementConstantExpr - This class is private to
 374 /// Constants.cpp, and is used behind the scenes to implement
 375 /// insertelement constant exprs.
 376 namespace {
 377 class VISIBILITY_HIDDEN InsertElementConstantExpr : public ConstantExpr {
 378   Use Ops[3];
 379 public:
 380   InsertElementConstantExpr(Constant *C1, Constant *C2, Constant *C3)
 381     : ConstantExpr(C1->getType(), Instruction::InsertElement,
 382                    Ops, 3) {
 383     Ops[0].init(C1, this);
 384     Ops[1].init(C2, this);
 385     Ops[2].init(C3, this);
 386   }
 387 };
 388 }
 389
 390 /// ShuffleVectorConstantExpr - This class is private to
 391 /// Constants.cpp, and is used behind the scenes to implement
 392 /// shufflevector constant exprs.
 393 namespace {
 394 class VISIBILITY_HIDDEN ShuffleVectorConstantExpr : public ConstantExpr {
 395   Use Ops[3];
 396 public:
 397   ShuffleVectorConstantExpr(Constant *C1, Constant *C2, Constant *C3)
 398   : ConstantExpr(C1->getType(), Instruction::ShuffleVector,
 399                  Ops, 3) {
 400     Ops[0].init(C1, this);
 401     Ops[1].init(C2, this);
 402     Ops[2].init(C3, this);
 403   }
 404 };
 405 }
 406
 407 /// GetElementPtrConstantExpr - This class is private to Constants.cpp, and is
 408 /// used behind the scenes to implement getelementpr constant exprs.
 409 namespace {
 410 struct VISIBILITY_HIDDEN GetElementPtrConstantExpr : public ConstantExpr {
 411   GetElementPtrConstantExpr(Constant *C, const std::vector<Constant*> &IdxList,
 412                             const Type *DestTy)
 413     : ConstantExpr(DestTy, Instruction::GetElementPtr,
 414                    new Use[IdxList.size()+1], IdxList.size()+1) {
 415     OperandList[0].init(C, this);
 416     for (unsigned i = 0, E = IdxList.size(); i != E; ++i)
 417       OperandList[i+1].init(IdxList[i], this);
 418   }
 419   ~GetElementPtrConstantExpr() {
 420     delete [] OperandList;
 421   }
 422 };
 423 }
 424
 425 /// ConstantExpr::get* - Return some common constants without having to
 426 /// specify the full Instruction::OPCODE identifier.
 427 ///
 428 Constant *ConstantExpr::getNeg(Constant *C) {
 429   if (!C->getType()->isFloatingPoint())
 430     return get(Instruction::Sub, getNullValue(C->getType()), C);
 431   else
 432     return get(Instruction::Sub, ConstantFP::get(C->getType(), -0.0), C);
 433 }
 434 Constant *ConstantExpr::getNot(Constant *C) {
 435   assert(isa<ConstantIntegral>(C) && "Cannot NOT a nonintegral type!");
 436   return get(Instruction::Xor, C,
 437              ConstantIntegral::getAllOnesValue(C->getType()));
 438 }
 439 Constant *ConstantExpr::getAdd(Constant *C1, Constant *C2) {
 440   return get(Instruction::Add, C1, C2);
 441 }
 442 Constant *ConstantExpr::getSub(Constant *C1, Constant *C2) {
 443   return get(Instruction::Sub, C1, C2);
 444 }
 445 Constant *ConstantExpr::getMul(Constant *C1, Constant *C2) {
 446   return get(Instruction::Mul, C1, C2);
 447 }
 448 Constant *ConstantExpr::getDiv(Constant *C1, Constant *C2) {
 449   return get(Instruction::Div, C1, C2);
 450 }
 451 Constant *ConstantExpr::getRem(Constant *C1, Constant *C2) {
 452   return get(Instruction::Rem, C1, C2);
 453 }
 454 Constant *ConstantExpr::getAnd(Constant *C1, Constant *C2) {
 455   return get(Instruction::And, C1, C2);
 456 }
 457 Constant *ConstantExpr::getOr(Constant *C1, Constant *C2) {
 458   return get(Instruction::Or, C1, C2);
 459 }
 460 Constant *ConstantExpr::getXor(Constant *C1, Constant *C2) {
 461   return get(Instruction::Xor, C1, C2);
 462 }
 463 Constant *ConstantExpr::getSetEQ(Constant *C1, Constant *C2) {
 464   return get(Instruction::SetEQ, C1, C2);
 465 }
 466 Constant *ConstantExpr::getSetNE(Constant *C1, Constant *C2) {
 467   return get(Instruction::SetNE, C1, C2);
 468 }
 469 Constant *ConstantExpr::getSetLT(Constant *C1, Constant *C2) {
 470   return get(Instruction::SetLT, C1, C2);
 471 }
 472 Constant *ConstantExpr::getSetGT(Constant *C1, Constant *C2) {
 473   return get(Instruction::SetGT, C1, C2);
 474 }
 475 Constant *ConstantExpr::getSetLE(Constant *C1, Constant *C2) {
 476   return get(Instruction::SetLE, C1, C2);
 477 }
 478 Constant *ConstantExpr::getSetGE(Constant *C1, Constant *C2) {
 479   return get(Instruction::SetGE, C1, C2);
 480 }
 481 Constant *ConstantExpr::getShl(Constant *C1, Constant *C2) {
 482   return get(Instruction::Shl, C1, C2);
 483 }
 484 Constant *ConstantExpr::getShr(Constant *C1, Constant *C2) {
 485   return get(Instruction::Shr, C1, C2);
 486 }
 487
 488 Constant *ConstantExpr::getUShr(Constant *C1, Constant *C2) {
 489   if (C1->getType()->isUnsigned()) return getShr(C1, C2);
 490   return getCast(getShr(getCast(C1,
 491                     C1->getType()->getUnsignedVersion()), C2), C1->getType());
 492 }
 493
 494 Constant *ConstantExpr::getSShr(Constant *C1, Constant *C2) {
 495   if (C1->getType()->isSigned()) return getShr(C1, C2);
 496   return getCast(getShr(getCast(C1,
 497                         C1->getType()->getSignedVersion()), C2), C1->getType());
 498 }
 499
 500 /// getWithOperandReplaced - Return a constant expression identical to this
 501 /// one, but with the specified operand set to the specified value.
 502 Constant *ConstantExpr::getWithOperandReplaced(unsigned OpNo,
 503                                                Constant *Op) const {
 504   assert(OpNo < getNumOperands() && "Operand num is out of range!");
 505   assert(Op->getType() == getOperand(OpNo)->getType() &&
 506          "Replacing operand with value of different type!");
 507   if (getOperand(OpNo) == Op)
 508     return const_cast<ConstantExpr*>(this);
 509
 510   Constant *Op0, *Op1, *Op2;
 511   switch (getOpcode()) {
 512   case Instruction::Cast:
 513     return ConstantExpr::getCast(Op, getType());
 514   case Instruction::Select:
 515     Op0 = (OpNo == 0) ? Op : getOperand(0);
 516     Op1 = (OpNo == 1) ? Op : getOperand(1);
 517     Op2 = (OpNo == 2) ? Op : getOperand(2);
 518     return ConstantExpr::getSelect(Op0, Op1, Op2);
 519   case Instruction::InsertElement:
 520     Op0 = (OpNo == 0) ? Op : getOperand(0);
 521     Op1 = (OpNo == 1) ? Op : getOperand(1);
 522     Op2 = (OpNo == 2) ? Op : getOperand(2);
 523     return ConstantExpr::getInsertElement(Op0, Op1, Op2);
 524   case Instruction::ExtractElement:
 525     Op0 = (OpNo == 0) ? Op : getOperand(0);
 526     Op1 = (OpNo == 1) ? Op : getOperand(1);
 527     return ConstantExpr::getExtractElement(Op0, Op1);
 528   case Instruction::ShuffleVector:
 529     Op0 = (OpNo == 0) ? Op : getOperand(0);
 530     Op1 = (OpNo == 1) ? Op : getOperand(1);
 531     Op2 = (OpNo == 2) ? Op : getOperand(2);
 532     return ConstantExpr::getShuffleVector(Op0, Op1, Op2);
 533   case Instruction::GetElementPtr: {
 534     std::vector<Constant*> Ops;
 535     for (unsigned i = 1, e = getNumOperands(); i != e; ++i)
 536       Ops.push_back(getOperand(i));
 537     if (OpNo == 0)
 538       return ConstantExpr::getGetElementPtr(Op, Ops);
 539     Ops[OpNo-1] = Op;
 540     return ConstantExpr::getGetElementPtr(getOperand(0), Ops);
 541   }
 542   default:
 543     assert(getNumOperands() == 2 && "Must be binary operator?");
 544     Op0 = (OpNo == 0) ? Op : getOperand(0);
 545     Op1 = (OpNo == 1) ? Op : getOperand(1);
 546     return ConstantExpr::get(getOpcode(), Op0, Op1);
 547   }
 548 }
 549
 550 /// getWithOperands - This returns the current constant expression with the
 551 /// operands replaced with the specified values.  The specified operands must
 552 /// match count and type with the existing ones.
 553 Constant *ConstantExpr::
 554 getWithOperands(const std::vector<Constant*> &Ops) const {
 555   assert(Ops.size() == getNumOperands() && "Operand count mismatch!");
 556   bool AnyChange = false;
 557   for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
 558     assert(Ops[i]->getType() == getOperand(i)->getType() &&
 559            "Operand type mismatch!");
 560     AnyChange |= Ops[i] != getOperand(i);
 561   }
 562   if (!AnyChange)  // No operands changed, return self.
 563     return const_cast<ConstantExpr*>(this);
 564
 565   switch (getOpcode()) {
 566   case Instruction::Cast:
 567     return ConstantExpr::getCast(Ops[0], getType());
 568   case Instruction::Select:
 569     return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
 570   case Instruction::InsertElement:
 571     return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]);
 572   case Instruction::ExtractElement:
 573     return ConstantExpr::getExtractElement(Ops[0], Ops[1]);
 574   case Instruction::ShuffleVector:
 575     return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]);
 576   case Instruction::GetElementPtr: {
 577     std::vector<Constant*> ActualOps(Ops.begin()+1, Ops.end());
 578     return ConstantExpr::getGetElementPtr(Ops[0], ActualOps);
 579   }
 580   default:
 581     assert(getNumOperands() == 2 && "Must be binary operator?");
 582     return ConstantExpr::get(getOpcode(), Ops[0], Ops[1]);
 583   }
 584 }
 585
 586
 587 //===----------------------------------------------------------------------===//
 588 //                      isValueValidForType implementations
 589
 590 bool ConstantSInt::isValueValidForType(const Type *Ty, int64_t Val) {
 591   switch (Ty->getTypeID()) {
 592   default:
 593     return false;         // These can't be represented as integers!!!
 594     // Signed types...
 595   case Type::SByteTyID:
 596     return (Val <= INT8_MAX && Val >= INT8_MIN);
 597   case Type::ShortTyID:
 598     return (Val <= INT16_MAX && Val >= INT16_MIN);
 599   case Type::IntTyID:
 600     return (Val <= int(INT32_MAX) && Val >= int(INT32_MIN));
 601   case Type::LongTyID:
 602     return true;          // This is the largest type...
 603   }
 604 }
 605
 606 bool ConstantUInt::isValueValidForType(const Type *Ty, uint64_t Val) {
 607   switch (Ty->getTypeID()) {
 608   default:
 609     return false;         // These can't be represented as integers!!!
 610
 611     // Unsigned types...
 612   case Type::UByteTyID:
 613     return (Val <= UINT8_MAX);
 614   case Type::UShortTyID:
 615     return (Val <= UINT16_MAX);
 616   case Type::UIntTyID:
 617     return (Val <= UINT32_MAX);
 618   case Type::ULongTyID:
 619     return true;          // This is the largest type...
 620   }
 621 }
 622
 623 bool ConstantFP::isValueValidForType(const Type *Ty, double Val) {
 624   switch (Ty->getTypeID()) {
 625   default:
 626     return false;         // These can't be represented as floating point!
 627
 628     // TODO: Figure out how to test if a double can be cast to a float!
 629   case Type::FloatTyID:
 630   case Type::DoubleTyID:
 631     return true;          // This is the largest type...
 632   }
 633 }
 634
 635 //===----------------------------------------------------------------------===//
 636 //                      Factory Function Implementation
 637
 638 // ConstantCreator - A class that is used to create constants by
 639 // ValueMap*.  This class should be partially specialized if there is
 640 // something strange that needs to be done to interface to the ctor for the
 641 // constant.
 642 //
 643 namespace llvm {
 644   template<class ConstantClass, class TypeClass, class ValType>
 645   struct VISIBILITY_HIDDEN ConstantCreator {
 646     static ConstantClass *create(const TypeClass *Ty, const ValType &V) {
 647       return new ConstantClass(Ty, V);
 648     }
 649   };
 650
 651   template<class ConstantClass, class TypeClass>
 652   struct VISIBILITY_HIDDEN ConvertConstantType {
 653     static void convert(ConstantClass *OldC, const TypeClass *NewTy) {
 654       assert(0 && "This type cannot be converted!\n");
 655       abort();
 656     }
 657   };
 658
 659   template<class ValType, class TypeClass, class ConstantClass,
 660            bool HasLargeKey = false  /*true for arrays and structs*/ >
 661   class VISIBILITY_HIDDEN ValueMap : public AbstractTypeUser {
 662   public:
 663     typedef std::pair<const Type*, ValType> MapKey;
 664     typedef std::map<MapKey, Constant *> MapTy;
 665     typedef std::map<Constant*, typename MapTy::iterator> InverseMapTy;
 666     typedef std::map<const Type*, typename MapTy::iterator> AbstractTypeMapTy;
 667   private:
 668     /// Map - This is the main map from the element descriptor to the Constants.
 669     /// This is the primary way we avoid creating two of the same shape
 670     /// constant.
 671     MapTy Map;
 672
 673     /// InverseMap - If "HasLargeKey" is true, this contains an inverse mapping
 674     /// from the constants to their element in Map.  This is important for
 675     /// removal of constants from the array, which would otherwise have to scan
 676     /// through the map with very large keys.
 677     InverseMapTy InverseMap;
 678
 679     /// AbstractTypeMap - Map for abstract type constants.
 680     ///
 681     AbstractTypeMapTy AbstractTypeMap;
 682
 683     friend void Constant::clearAllValueMaps();
 684   private:
 685     void clear(std::vector<Constant *> &Constants) {
 686       for(typename MapTy::iterator I = Map.begin(); I != Map.end(); ++I)
 687         Constants.push_back(I->second);
 688       Map.clear();
 689       AbstractTypeMap.clear();
 690       InverseMap.clear();
 691     }
 692
 693   public:
 694     typename MapTy::iterator map_end() { return Map.end(); }
 695
 696     /// InsertOrGetItem - Return an iterator for the specified element.
 697     /// If the element exists in the map, the returned iterator points to the
 698     /// entry and Exists=true.  If not, the iterator points to the newly
 699     /// inserted entry and returns Exists=false.  Newly inserted entries have
 700     /// I->second == 0, and should be filled in.
 701     typename MapTy::iterator InsertOrGetItem(std::pair<MapKey, Constant *>
 702                                    &InsertVal,
 703                                    bool &Exists) {
 704       std::pair<typename MapTy::iterator, bool> IP = Map.insert(InsertVal);
 705       Exists = !IP.second;
 706       return IP.first;
 707     }
 708
 709 private:
 710     typename MapTy::iterator FindExistingElement(ConstantClass *CP) {
 711       if (HasLargeKey) {
 712         typename InverseMapTy::iterator IMI = InverseMap.find(CP);
 713         assert(IMI != InverseMap.end() && IMI->second != Map.end() &&
 714                IMI->second->second == CP &&
 715                "InverseMap corrupt!");
 716         return IMI->second;
 717       }
 718
 719       typename MapTy::iterator I =
 720         Map.find(MapKey((TypeClass*)CP->getRawType(), getValType(CP)));
 721       if (I == Map.end() || I->second != CP) {
 722         // FIXME: This should not use a linear scan.  If this gets to be a
 723         // performance problem, someone should look at this.
 724         for (I = Map.begin(); I != Map.end() && I->second != CP; ++I)
 725           /* empty */;
 726       }
 727       return I;
 728     }
 729 public:
 730
 731     /// getOrCreate - Return the specified constant from the map, creating it if
 732     /// necessary.
 733     ConstantClass *getOrCreate(const TypeClass *Ty, const ValType &V) {
 734       MapKey Lookup(Ty, V);
 735       typename MapTy::iterator I = Map.lower_bound(Lookup);
 736       if (I != Map.end() && I->first == Lookup)
 737         return static_cast<ConstantClass *>(I->second);  // Is it in the map?
 738
 739       // If no preexisting value, create one now...
 740       ConstantClass *Result =
 741         ConstantCreator<ConstantClass,TypeClass,ValType>::create(Ty, V);
 742
 743       /// FIXME: why does this assert fail when loading 176.gcc?
 744       //assert(Result->getType() == Ty && "Type specified is not correct!");
 745       I = Map.insert(I, std::make_pair(MapKey(Ty, V), Result));
 746
 747       if (HasLargeKey)  // Remember the reverse mapping if needed.
 748         InverseMap.insert(std::make_pair(Result, I));
 749
 750       // If the type of the constant is abstract, make sure that an entry exists
 751       // for it in the AbstractTypeMap.
 752       if (Ty->isAbstract()) {
 753         typename AbstractTypeMapTy::iterator TI =
 754           AbstractTypeMap.lower_bound(Ty);
 755
 756         if (TI == AbstractTypeMap.end() || TI->first != Ty) {
 757           // Add ourselves to the ATU list of the type.
 758           cast<DerivedType>(Ty)->addAbstractTypeUser(this);
 759
 760           AbstractTypeMap.insert(TI, std::make_pair(Ty, I));
 761         }
 762       }
 763       return Result;
 764     }
 765
 766     void remove(ConstantClass *CP) {
 767       typename MapTy::iterator I = FindExistingElement(CP);
 768       assert(I != Map.end() && "Constant not found in constant table!");
 769       assert(I->second == CP && "Didn't find correct element?");
 770
 771       if (HasLargeKey)  // Remember the reverse mapping if needed.
 772         InverseMap.erase(CP);
 773
 774       // Now that we found the entry, make sure this isn't the entry that
 775       // the AbstractTypeMap points to.
 776       const TypeClass *Ty = static_cast<const TypeClass *>(I->first.first);
 777       if (Ty->isAbstract()) {
 778         assert(AbstractTypeMap.count(Ty) &&
 779                "Abstract type not in AbstractTypeMap?");
 780         typename MapTy::iterator &ATMEntryIt = AbstractTypeMap[Ty];
 781         if (ATMEntryIt == I) {
 782           // Yes, we are removing the representative entry for this type.
 783           // See if there are any other entries of the same type.
 784           typename MapTy::iterator TmpIt = ATMEntryIt;
 785
 786           // First check the entry before this one...
 787           if (TmpIt != Map.begin()) {
 788             --TmpIt;
 789             if (TmpIt->first.first != Ty) // Not the same type, move back...
 790               ++TmpIt;
 791           }
 792
 793           // If we didn't find the same type, try to move forward...
 794           if (TmpIt == ATMEntryIt) {
 795             ++TmpIt;
 796             if (TmpIt == Map.end() || TmpIt->first.first != Ty)
 797               --TmpIt;   // No entry afterwards with the same type
 798           }
 799
 800           // If there is another entry in the map of the same abstract type,
 801           // update the AbstractTypeMap entry now.
 802           if (TmpIt != ATMEntryIt) {
 803             ATMEntryIt = TmpIt;
 804           } else {
 805             // Otherwise, we are removing the last instance of this type
 806             // from the table.  Remove from the ATM, and from user list.
 807             cast<DerivedType>(Ty)->removeAbstractTypeUser(this);
 808             AbstractTypeMap.erase(Ty);
 809           }
 810         }
 811       }
 812
 813       Map.erase(I);
 814     }
 815
 816
 817     /// MoveConstantToNewSlot - If we are about to change C to be the element
 818     /// specified by I, update our internal data structures to reflect this
 819     /// fact.
 820     void MoveConstantToNewSlot(ConstantClass *C, typename MapTy::iterator I) {
 821       // First, remove the old location of the specified constant in the map.
 822       typename MapTy::iterator OldI = FindExistingElement(C);
 823       assert(OldI != Map.end() && "Constant not found in constant table!");
 824       assert(OldI->second == C && "Didn't find correct element?");
 825
 826       // If this constant is the representative element for its abstract type,
 827       // update the AbstractTypeMap so that the representative element is I.
 828       if (C->getType()->isAbstract()) {
 829         typename AbstractTypeMapTy::iterator ATI =
 830             AbstractTypeMap.find(C->getType());
 831         assert(ATI != AbstractTypeMap.end() &&
 832                "Abstract type not in AbstractTypeMap?");
 833         if (ATI->second == OldI)
 834           ATI->second = I;
 835       }
 836
 837       // Remove the old entry from the map.
 838       Map.erase(OldI);
 839
 840       // Update the inverse map so that we know that this constant is now
 841       // located at descriptor I.
 842       if (HasLargeKey) {
 843         assert(I->second == C && "Bad inversemap entry!");
 844         InverseMap[C] = I;
 845       }
 846     }
 847
 848     void refineAbstractType(const DerivedType *OldTy, const Type *NewTy) {
 849       typename AbstractTypeMapTy::iterator I =
 850         AbstractTypeMap.find(cast<Type>(OldTy));
 851
 852       assert(I != AbstractTypeMap.end() &&
 853              "Abstract type not in AbstractTypeMap?");
 854
 855       // Convert a constant at a time until the last one is gone.  The last one
 856       // leaving will remove() itself, causing the AbstractTypeMapEntry to be
 857       // eliminated eventually.
 858       do {
 859         ConvertConstantType<ConstantClass,
 860                             TypeClass>::convert(
 861                                 static_cast<ConstantClass *>(I->second->second),
 862                                                 cast<TypeClass>(NewTy));
 863
 864         I = AbstractTypeMap.find(cast<Type>(OldTy));
 865       } while (I != AbstractTypeMap.end());
 866     }
 867
 868     // If the type became concrete without being refined to any other existing
 869     // type, we just remove ourselves from the ATU list.
 870     void typeBecameConcrete(const DerivedType *AbsTy) {
 871       AbsTy->removeAbstractTypeUser(this);
 872     }
 873
 874     void dump() const {
 875       std::cerr << "Constant.cpp: ValueMap\n";
 876     }
 877   };
 878 }
 879
 880 //---- ConstantUInt::get() and ConstantSInt::get() implementations...
 881 //
 882 static ValueMap< int64_t, Type, ConstantSInt> SIntConstants;
 883 static ValueMap<uint64_t, Type, ConstantUInt> UIntConstants;
 884
 885 ConstantSInt *ConstantSInt::get(const Type *Ty, int64_t V) {
 886   return SIntConstants.getOrCreate(Ty, V);
 887 }
 888
 889 ConstantUInt *ConstantUInt::get(const Type *Ty, uint64_t V) {
 890   return UIntConstants.getOrCreate(Ty, V);
 891 }
 892
 893 ConstantInt *ConstantInt::get(const Type *Ty, unsigned char V) {
 894   assert(V <= 127 && "Can only be used with very small positive constants!");
 895   if (Ty->isSigned()) return ConstantSInt::get(Ty, V);
 896   return ConstantUInt::get(Ty, V);
 897 }
 898
 899 //---- ConstantFP::get() implementation...
 900 //
 901 namespace llvm {
 902   template<>
 903   struct ConstantCreator<ConstantFP, Type, uint64_t> {
 904     static ConstantFP *create(const Type *Ty, uint64_t V) {
 905       assert(Ty == Type::DoubleTy);
 906       return new ConstantFP(Ty, BitsToDouble(V));
 907     }
 908   };
 909   template<>
 910   struct ConstantCreator<ConstantFP, Type, uint32_t> {
 911     static ConstantFP *create(const Type *Ty, uint32_t V) {
 912       assert(Ty == Type::FloatTy);
 913       return new ConstantFP(Ty, BitsToFloat(V));
 914     }
 915   };
 916 }
 917
 918 static ValueMap<uint64_t, Type, ConstantFP> DoubleConstants;
 919 static ValueMap<uint32_t, Type, ConstantFP> FloatConstants;
 920
 921 bool ConstantFP::isNullValue() const {
 922   return DoubleToBits(Val) == 0;
 923 }
 924
 925 bool ConstantFP::isExactlyValue(double V) const {
 926   return DoubleToBits(V) == DoubleToBits(Val);
 927 }
 928
 929
 930 ConstantFP *ConstantFP::get(const Type *Ty, double V) {
 931   if (Ty == Type::FloatTy) {
 932     // Force the value through memory to normalize it.
 933     return FloatConstants.getOrCreate(Ty, FloatToBits(V));
 934   } else {
 935     assert(Ty == Type::DoubleTy);
 936     return DoubleConstants.getOrCreate(Ty, DoubleToBits(V));
 937   }
 938 }
 939
 940 //---- ConstantAggregateZero::get() implementation...
 941 //
 942 namespace llvm {
 943   // ConstantAggregateZero does not take extra "value" argument...
 944   template<class ValType>
 945   struct ConstantCreator<ConstantAggregateZero, Type, ValType> {
 946     static ConstantAggregateZero *create(const Type *Ty, const ValType &V){
 947       return new ConstantAggregateZero(Ty);
 948     }
 949   };
 950
 951   template<>
 952   struct ConvertConstantType<ConstantAggregateZero, Type> {
 953     static void convert(ConstantAggregateZero *OldC, const Type *NewTy) {
 954       // Make everyone now use a constant of the new type...
 955       Constant *New = ConstantAggregateZero::get(NewTy);
 956       assert(New != OldC && "Didn't replace constant??");
 957       OldC->uncheckedReplaceAllUsesWith(New);
 958       OldC->destroyConstant();     // This constant is now dead, destroy it.
 959     }
 960   };
 961 }
 962
 963 static ValueMap<char, Type, ConstantAggregateZero> AggZeroConstants;
 964
 965 static char getValType(ConstantAggregateZero *CPZ) { return 0; }
 966
 967 Constant *ConstantAggregateZero::get(const Type *Ty) {
 968   assert((isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<PackedType>(Ty)) &&
 969          "Cannot create an aggregate zero of non-aggregate type!");
 970   return AggZeroConstants.getOrCreate(Ty, 0);
 971 }
 972
 973 // destroyConstant - Remove the constant from the constant table...
 974 //
 975 void ConstantAggregateZero::destroyConstant() {
 976   AggZeroConstants.remove(this);
 977   destroyConstantImpl();
 978 }
 979
 980 //---- ConstantArray::get() implementation...
 981 //
 982 namespace llvm {
 983   template<>
 984   struct ConvertConstantType<ConstantArray, ArrayType> {
 985     static void convert(ConstantArray *OldC, const ArrayType *NewTy) {
 986       // Make everyone now use a constant of the new type...
 987       std::vector<Constant*> C;
 988       for (unsigned i = 0, e = OldC->getNumOperands(); i != e; ++i)
 989         C.push_back(cast<Constant>(OldC->getOperand(i)));
 990       Constant *New = ConstantArray::get(NewTy, C);
 991       assert(New != OldC && "Didn't replace constant??");
 992       OldC->uncheckedReplaceAllUsesWith(New);
 993       OldC->destroyConstant();    // This constant is now dead, destroy it.
 994     }
 995   };
 996 }
 997
 998 static std::vector<Constant*> getValType(ConstantArray *CA) {
 999   std::vector<Constant*> Elements;
1000   Elements.reserve(CA->getNumOperands());
1001   for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
1002     Elements.push_back(cast<Constant>(CA->getOperand(i)));
1003   return Elements;
1004 }
1005
1006 typedef ValueMap<std::vector<Constant*>, ArrayType,
1007                  ConstantArray, true /*largekey*/> ArrayConstantsTy;
1008 static ArrayConstantsTy ArrayConstants;
1009
1010 Constant *ConstantArray::get(const ArrayType *Ty,
1011                              const std::vector<Constant*> &V) {
1012   // If this is an all-zero array, return a ConstantAggregateZero object
1013   if (!V.empty()) {
1014     Constant *C = V[0];
1015     if (!C->isNullValue())
1016       return ArrayConstants.getOrCreate(Ty, V);
1017     for (unsigned i = 1, e = V.size(); i != e; ++i)
1018       if (V[i] != C)
1019         return ArrayConstants.getOrCreate(Ty, V);
1020   }
1021   return ConstantAggregateZero::get(Ty);
1022 }
1023
1024 // destroyConstant - Remove the constant from the constant table...
1025 //
1026 void ConstantArray::destroyConstant() {
1027   ArrayConstants.remove(this);
1028   destroyConstantImpl();
1029 }
1030
1031 /// ConstantArray::get(const string&) - Return an array that is initialized to
1032 /// contain the specified string.  If length is zero then a null terminator is
1033 /// added to the specified string so that it may be used in a natural way.
1034 /// Otherwise, the length parameter specifies how much of the string to use
1035 /// and it won't be null terminated.
1036 ///
1037 Constant *ConstantArray::get(const std::string &Str, bool AddNull) {
1038   std::vector<Constant*> ElementVals;
1039   for (unsigned i = 0; i < Str.length(); ++i)
1040     ElementVals.push_back(ConstantSInt::get(Type::SByteTy, Str[i]));
1041
1042   // Add a null terminator to the string...
1043   if (AddNull) {
1044     ElementVals.push_back(ConstantSInt::get(Type::SByteTy, 0));
1045   }
1046
1047   ArrayType *ATy = ArrayType::get(Type::SByteTy, ElementVals.size());
1048   return ConstantArray::get(ATy, ElementVals);
1049 }
1050
1051 /// isString - This method returns true if the array is an array of sbyte or
1052 /// ubyte, and if the elements of the array are all ConstantInt's.
1053 bool ConstantArray::isString() const {
1054   // Check the element type for sbyte or ubyte...
1055   if (getType()->getElementType() != Type::UByteTy &&
1056       getType()->getElementType() != Type::SByteTy)
1057     return false;
1058   // Check the elements to make sure they are all integers, not constant
1059   // expressions.
1060   for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
1061     if (!isa<ConstantInt>(getOperand(i)))
1062       return false;
1063   return true;
1064 }
1065
1066 // getAsString - If the sub-element type of this array is either sbyte or ubyte,
1067 // then this method converts the array to an std::string and returns it.
1068 // Otherwise, it asserts out.
1069 //
1070 std::string ConstantArray::getAsString() const {
1071   assert(isString() && "Not a string!");
1072   std::string Result;
1073   for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
1074     Result += (char)cast<ConstantInt>(getOperand(i))->getRawValue();
1075   return Result;
1076 }
1077
1078
1079 //---- ConstantStruct::get() implementation...
1080 //
1081
1082 namespace llvm {
1083   template<>
1084   struct ConvertConstantType<ConstantStruct, StructType> {
1085     static void convert(ConstantStruct *OldC, const StructType *NewTy) {
1086       // Make everyone now use a constant of the new type...
1087       std::vector<Constant*> C;
1088       for (unsigned i = 0, e = OldC->getNumOperands(); i != e; ++i)
1089         C.push_back(cast<Constant>(OldC->getOperand(i)));
1090       Constant *New = ConstantStruct::get(NewTy, C);
1091       assert(New != OldC && "Didn't replace constant??");
1092
1093       OldC->uncheckedReplaceAllUsesWith(New);
1094       OldC->destroyConstant();    // This constant is now dead, destroy it.
1095     }
1096   };
1097 }
1098
1099 typedef ValueMap<std::vector<Constant*>, StructType,
1100                  ConstantStruct, true /*largekey*/> StructConstantsTy;
1101 static StructConstantsTy StructConstants;
1102
1103 static std::vector<Constant*> getValType(ConstantStruct *CS) {
1104   std::vector<Constant*> Elements;
1105   Elements.reserve(CS->getNumOperands());
1106   for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i)
1107     Elements.push_back(cast<Constant>(CS->getOperand(i)));
1108   return Elements;
1109 }
1110
1111 Constant *ConstantStruct::get(const StructType *Ty,
1112                               const std::vector<Constant*> &V) {
1113   // Create a ConstantAggregateZero value if all elements are zeros...
1114   for (unsigned i = 0, e = V.size(); i != e; ++i)
1115     if (!V[i]->isNullValue())
1116       return StructConstants.getOrCreate(Ty, V);
1117
1118   return ConstantAggregateZero::get(Ty);
1119 }
1120
1121 Constant *ConstantStruct::get(const std::vector<Constant*> &V) {
1122   std::vector<const Type*> StructEls;
1123   StructEls.reserve(V.size());
1124   for (unsigned i = 0, e = V.size(); i != e; ++i)
1125     StructEls.push_back(V[i]->getType());
1126   return get(StructType::get(StructEls), V);
1127 }
1128
1129 // destroyConstant - Remove the constant from the constant table...
1130 //
1131 void ConstantStruct::destroyConstant() {
1132   StructConstants.remove(this);
1133   destroyConstantImpl();
1134 }
1135
1136 //---- ConstantPacked::get() implementation...
1137 //
1138 namespace llvm {
1139   template<>
1140   struct ConvertConstantType<ConstantPacked, PackedType> {
1141     static void convert(ConstantPacked *OldC, const PackedType *NewTy) {
1142       // Make everyone now use a constant of the new type...
1143       std::vector<Constant*> C;
1144       for (unsigned i = 0, e = OldC->getNumOperands(); i != e; ++i)
1145         C.push_back(cast<Constant>(OldC->getOperand(i)));
1146       Constant *New = ConstantPacked::get(NewTy, C);
1147       assert(New != OldC && "Didn't replace constant??");
1148       OldC->uncheckedReplaceAllUsesWith(New);
1149       OldC->destroyConstant();    // This constant is now dead, destroy it.
1150     }
1151   };
1152 }
1153
1154 static std::vector<Constant*> getValType(ConstantPacked *CP) {
1155   std::vector<Constant*> Elements;
1156   Elements.reserve(CP->getNumOperands());
1157   for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
1158     Elements.push_back(CP->getOperand(i));
1159   return Elements;
1160 }
1161
1162 static ValueMap<std::vector<Constant*>, PackedType,
1163                 ConstantPacked> PackedConstants;
1164
1165 Constant *ConstantPacked::get(const PackedType *Ty,
1166                               const std::vector<Constant*> &V) {
1167   // If this is an all-zero packed, return a ConstantAggregateZero object
1168   if (!V.empty()) {
1169     Constant *C = V[0];
1170     if (!C->isNullValue())
1171       return PackedConstants.getOrCreate(Ty, V);
1172     for (unsigned i = 1, e = V.size(); i != e; ++i)
1173       if (V[i] != C)
1174         return PackedConstants.getOrCreate(Ty, V);
1175   }
1176   return ConstantAggregateZero::get(Ty);
1177 }
1178
1179 Constant *ConstantPacked::get(const std::vector<Constant*> &V) {
1180   assert(!V.empty() && "Cannot infer type if V is empty");
1181   return get(PackedType::get(V.front()->getType(),V.size()), V);
1182 }
1183
1184 // destroyConstant - Remove the constant from the constant table...
1185 //
1186 void ConstantPacked::destroyConstant() {
1187   PackedConstants.remove(this);
1188   destroyConstantImpl();
1189 }
1190
1191 //---- ConstantPointerNull::get() implementation...
1192 //
1193
1194 namespace llvm {
1195   // ConstantPointerNull does not take extra "value" argument...
1196   template<class ValType>
1197   struct ConstantCreator<ConstantPointerNull, PointerType, ValType> {
1198     static ConstantPointerNull *create(const PointerType *Ty, const ValType &V){
1199       return new ConstantPointerNull(Ty);
1200     }
1201   };
1202
1203   template<>
1204   struct ConvertConstantType<ConstantPointerNull, PointerType> {
1205     static void convert(ConstantPointerNull *OldC, const PointerType *NewTy) {
1206       // Make everyone now use a constant of the new type...
1207       Constant *New = ConstantPointerNull::get(NewTy);
1208       assert(New != OldC && "Didn't replace constant??");
1209       OldC->uncheckedReplaceAllUsesWith(New);
1210       OldC->destroyConstant();     // This constant is now dead, destroy it.
1211     }
1212   };
1213 }
1214
1215 static ValueMap<char, PointerType, ConstantPointerNull> NullPtrConstants;
1216
1217 static char getValType(ConstantPointerNull *) {
1218   return 0;
1219 }
1220
1221
1222 ConstantPointerNull *ConstantPointerNull::get(const PointerType *Ty) {
1223   return NullPtrConstants.getOrCreate(Ty, 0);
1224 }
1225
1226 // destroyConstant - Remove the constant from the constant table...
1227 //
1228 void ConstantPointerNull::destroyConstant() {
1229   NullPtrConstants.remove(this);
1230   destroyConstantImpl();
1231 }
1232
1233
1234 //---- UndefValue::get() implementation...
1235 //
1236
1237 namespace llvm {
1238   // UndefValue does not take extra "value" argument...
1239   template<class ValType>
1240   struct ConstantCreator<UndefValue, Type, ValType> {
1241     static UndefValue *create(const Type *Ty, const ValType &V) {
1242       return new UndefValue(Ty);
1243     }
1244   };
1245
1246   template<>
1247   struct ConvertConstantType<UndefValue, Type> {
1248     static void convert(UndefValue *OldC, const Type *NewTy) {
1249       // Make everyone now use a constant of the new type.
1250       Constant *New = UndefValue::get(NewTy);
1251       assert(New != OldC && "Didn't replace constant??");
1252       OldC->uncheckedReplaceAllUsesWith(New);
1253       OldC->destroyConstant();     // This constant is now dead, destroy it.
1254     }
1255   };
1256 }
1257
1258 static ValueMap<char, Type, UndefValue> UndefValueConstants;
1259
1260 static char getValType(UndefValue *) {
1261   return 0;
1262 }
1263
1264
1265 UndefValue *UndefValue::get(const Type *Ty) {
1266   return UndefValueConstants.getOrCreate(Ty, 0);
1267 }
1268
1269 // destroyConstant - Remove the constant from the constant table.
1270 //
1271 void UndefValue::destroyConstant() {
1272   UndefValueConstants.remove(this);
1273   destroyConstantImpl();
1274 }
1275
1276
1277
1278
1279 //---- ConstantExpr::get() implementations...
1280 //
1281 typedef std::pair<unsigned, std::vector<Constant*> > ExprMapKeyType;
1282
1283 namespace llvm {
1284   template<>
1285   struct ConstantCreator<ConstantExpr, Type, ExprMapKeyType> {
1286     static ConstantExpr *create(const Type *Ty, const ExprMapKeyType &V) {
1287       if (V.first == Instruction::Cast)
1288         return new UnaryConstantExpr(Instruction::Cast, V.second[0], Ty);
1289       if ((V.first >= Instruction::BinaryOpsBegin &&
1290            V.first < Instruction::BinaryOpsEnd) ||
1291           V.first == Instruction::Shl || V.first == Instruction::Shr)
1292         return new BinaryConstantExpr(V.first, V.second[0], V.second[1]);
1293       if (V.first == Instruction::Select)
1294         return new SelectConstantExpr(V.second[0], V.second[1], V.second[2]);
1295       if (V.first == Instruction::ExtractElement)
1296         return new ExtractElementConstantExpr(V.second[0], V.second[1]);
1297       if (V.first == Instruction::InsertElement)
1298         return new InsertElementConstantExpr(V.second[0], V.second[1],
1299                                              V.second[2]);
1300       if (V.first == Instruction::ShuffleVector)
1301         return new ShuffleVectorConstantExpr(V.second[0], V.second[1],
1302                                              V.second[2]);
1303
1304       assert(V.first == Instruction::GetElementPtr && "Invalid ConstantExpr!");
1305
1306       std::vector<Constant*> IdxList(V.second.begin()+1, V.second.end());
1307       return new GetElementPtrConstantExpr(V.second[0], IdxList, Ty);
1308     }
1309   };
1310
1311   template<>
1312   struct ConvertConstantType<ConstantExpr, Type> {
1313     static void convert(ConstantExpr *OldC, const Type *NewTy) {
1314       Constant *New;
1315       switch (OldC->getOpcode()) {
1316       case Instruction::Cast:
1317         New = ConstantExpr::getCast(OldC->getOperand(0), NewTy);
1318         break;
1319       case Instruction::Select:
1320         New = ConstantExpr::getSelectTy(NewTy, OldC->getOperand(0),
1321                                         OldC->getOperand(1),
1322                                         OldC->getOperand(2));
1323         break;
1324       case Instruction::Shl:
1325       case Instruction::Shr:
1326         New = ConstantExpr::getShiftTy(NewTy, OldC->getOpcode(),
1327                                      OldC->getOperand(0), OldC->getOperand(1));
1328         break;
1329       default:
1330         assert(OldC->getOpcode() >= Instruction::BinaryOpsBegin &&
1331                OldC->getOpcode() < Instruction::BinaryOpsEnd);
1332         New = ConstantExpr::getTy(NewTy, OldC->getOpcode(), OldC->getOperand(0),
1333                                   OldC->getOperand(1));
1334         break;
1335       case Instruction::GetElementPtr:
1336         // Make everyone now use a constant of the new type...
1337         std::vector<Value*> Idx(OldC->op_begin()+1, OldC->op_end());
1338         New = ConstantExpr::getGetElementPtrTy(NewTy, OldC->getOperand(0), Idx);
1339         break;
1340       }
1341
1342       assert(New != OldC && "Didn't replace constant??");
1343       OldC->uncheckedReplaceAllUsesWith(New);
1344       OldC->destroyConstant();    // This constant is now dead, destroy it.
1345     }
1346   };
1347 } // end namespace llvm
1348
1349
1350 static ExprMapKeyType getValType(ConstantExpr *CE) {
1351   std::vector<Constant*> Operands;
1352   Operands.reserve(CE->getNumOperands());
1353   for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i)
1354     Operands.push_back(cast<Constant>(CE->getOperand(i)));
1355   return ExprMapKeyType(CE->getOpcode(), Operands);
1356 }
1357
1358 static ValueMap<ExprMapKeyType, Type, ConstantExpr> ExprConstants;
1359
1360 Constant *ConstantExpr::getCast(Constant *C, const Type *Ty) {
1361   assert(Ty->isFirstClassType() && "Cannot cast to an aggregate type!");
1362
1363   if (Constant *FC = ConstantFoldCastInstruction(C, Ty))
1364     return FC;          // Fold a few common cases...
1365
1366   // Look up the constant in the table first to ensure uniqueness
1367   std::vector<Constant*> argVec(1, C);
1368   ExprMapKeyType Key = std::make_pair(Instruction::Cast, argVec);
1369   return ExprConstants.getOrCreate(Ty, Key);
1370 }
1371
1372 Constant *ConstantExpr::getSignExtend(Constant *C, const Type *Ty) {
1373   assert(C->getType()->isIntegral() && Ty->isIntegral() &&
1374          C->getType()->getPrimitiveSize() <= Ty->getPrimitiveSize() &&
1375          "This is an illegal sign extension!");
1376   if (C->getType() != Type::BoolTy) {
1377     C = ConstantExpr::getCast(C, C->getType()->getSignedVersion());
1378     return ConstantExpr::getCast(C, Ty);
1379   } else {
1380     if (C == ConstantBool::True)
1381       return ConstantIntegral::getAllOnesValue(Ty);
1382     else
1383       return ConstantIntegral::getNullValue(Ty);
1384   }
1385 }
1386
1387 Constant *ConstantExpr::getZeroExtend(Constant *C, const Type *Ty) {
1388   assert(C->getType()->isIntegral() && Ty->isIntegral() &&
1389          C->getType()->getPrimitiveSize() <= Ty->getPrimitiveSize() &&
1390          "This is an illegal zero extension!");
1391   if (C->getType() != Type::BoolTy)
1392     C = ConstantExpr::getCast(C, C->getType()->getUnsignedVersion());
1393   return ConstantExpr::getCast(C, Ty);
1394 }
1395
1396 Constant *ConstantExpr::getSizeOf(const Type *Ty) {
1397   // sizeof is implemented as: (ulong) gep (Ty*)null, 1
1398   return getCast(
1399     getGetElementPtr(getNullValue(PointerType::get(Ty)),
1400                  std::vector<Constant*>(1, ConstantInt::get(Type::UIntTy, 1))),
1401     Type::ULongTy);
1402 }
1403
1404 Constant *ConstantExpr::getPtrPtrFromArrayPtr(Constant *C) {
1405   // pointer from array is implemented as: getelementptr arr ptr, 0, 0
1406   static std::vector<Constant*> Indices(2, ConstantUInt::get(Type::UIntTy, 0));
1407
1408   return ConstantExpr::getGetElementPtr(C, Indices);
1409 }
1410
1411 Constant *ConstantExpr::getTy(const Type *ReqTy, unsigned Opcode,
1412                               Constant *C1, Constant *C2) {
1413   if (Opcode == Instruction::Shl || Opcode == Instruction::Shr)
1414     return getShiftTy(ReqTy, Opcode, C1, C2);
1415   // Check the operands for consistency first
1416   assert((Opcode >= Instruction::BinaryOpsBegin &&
1417           Opcode < Instruction::BinaryOpsEnd) &&
1418          "Invalid opcode in binary constant expression");
1419   assert(C1->getType() == C2->getType() &&
1420          "Operand types in binary constant expression should match");
1421
1422   if (ReqTy == C1->getType() || (Instruction::isRelational(Opcode) &&
1423                                  ReqTy == Type::BoolTy))
1424     if (Constant *FC = ConstantFoldBinaryInstruction(Opcode, C1, C2))
1425       return FC;          // Fold a few common cases...
1426
1427   std::vector<Constant*> argVec(1, C1); argVec.push_back(C2);
1428   ExprMapKeyType Key = std::make_pair(Opcode, argVec);
1429   return ExprConstants.getOrCreate(ReqTy, Key);
1430 }
1431
1432 Constant *ConstantExpr::get(unsigned Opcode, Constant *C1, Constant *C2) {
1433 #ifndef NDEBUG
1434   switch (Opcode) {
1435   case Instruction::Add: case Instruction::Sub:
1436   case Instruction::Mul: case Instruction::Div:
1437   case Instruction::Rem:
1438     assert(C1->getType() == C2->getType() && "Op types should be identical!");
1439     assert((C1->getType()->isInteger() || C1->getType()->isFloatingPoint() ||
1440             isa<PackedType>(C1->getType())) &&
1441            "Tried to create an arithmetic operation on a non-arithmetic type!");
1442     break;
1443   case Instruction::And:
1444   case Instruction::Or:
1445   case Instruction::Xor:
1446     assert(C1->getType() == C2->getType() && "Op types should be identical!");
1447     assert((C1->getType()->isIntegral() || isa<PackedType>(C1->getType())) &&
1448            "Tried to create a logical operation on a non-integral type!");
1449     break;
1450   case Instruction::SetLT: case Instruction::SetGT: case Instruction::SetLE:
1451   case Instruction::SetGE: case Instruction::SetEQ: case Instruction::SetNE:
1452     assert(C1->getType() == C2->getType() && "Op types should be identical!");
1453     break;
1454   case Instruction::Shl:
1455   case Instruction::Shr:
1456     assert(C2->getType() == Type::UByteTy && "Shift should be by ubyte!");
1457     assert((C1->getType()->isInteger() || isa<PackedType>(C1->getType())) &&
1458            "Tried to create a shift operation on a non-integer type!");
1459     break;
1460   default:
1461     break;
1462   }
1463 #endif
1464
1465   if (Instruction::isRelational(Opcode))
1466     return getTy(Type::BoolTy, Opcode, C1, C2);
1467   else
1468     return getTy(C1->getType(), Opcode, C1, C2);
1469 }
1470
1471 Constant *ConstantExpr::getSelectTy(const Type *ReqTy, Constant *C,
1472                                     Constant *V1, Constant *V2) {
1473   assert(C->getType() == Type::BoolTy && "Select condition must be bool!");
1474   assert(V1->getType() == V2->getType() && "Select value types must match!");
1475   assert(V1->getType()->isFirstClassType() && "Cannot select aggregate type!");
1476
1477   if (ReqTy == V1->getType())
1478     if (Constant *SC = ConstantFoldSelectInstruction(C, V1, V2))
1479       return SC;        // Fold common cases
1480
1481   std::vector<Constant*> argVec(3, C);
1482   argVec[1] = V1;
1483   argVec[2] = V2;
1484   ExprMapKeyType Key = std::make_pair(Instruction::Select, argVec);
1485   return ExprConstants.getOrCreate(ReqTy, Key);
1486 }
1487
1488 /// getShiftTy - Return a shift left or shift right constant expr
1489 Constant *ConstantExpr::getShiftTy(const Type *ReqTy, unsigned Opcode,
1490                                    Constant *C1, Constant *C2) {
1491   // Check the operands for consistency first
1492   assert((Opcode == Instruction::Shl ||
1493           Opcode == Instruction::Shr) &&
1494          "Invalid opcode in binary constant expression");
1495   assert(C1->getType()->isIntegral() && C2->getType() == Type::UByteTy &&
1496          "Invalid operand types for Shift constant expr!");
1497
1498   if (Constant *FC = ConstantFoldBinaryInstruction(Opcode, C1, C2))
1499     return FC;          // Fold a few common cases...
1500
1501   // Look up the constant in the table first to ensure uniqueness
1502   std::vector<Constant*> argVec(1, C1); argVec.push_back(C2);
1503   ExprMapKeyType Key = std::make_pair(Opcode, argVec);
1504   return ExprConstants.getOrCreate(ReqTy, Key);
1505 }
1506
1507
1508 Constant *ConstantExpr::getGetElementPtrTy(const Type *ReqTy, Constant *C,
1509                                            const std::vector<Value*> &IdxList) {
1510   assert(GetElementPtrInst::getIndexedType(C->getType(), IdxList, true) &&
1511          "GEP indices invalid!");
1512
1513   if (Constant *FC = ConstantFoldGetElementPtr(C, IdxList))
1514     return FC;          // Fold a few common cases...
1515
1516   assert(isa<PointerType>(C->getType()) &&
1517          "Non-pointer type for constant GetElementPtr expression");
1518   // Look up the constant in the table first to ensure uniqueness
1519   std::vector<Constant*> ArgVec;
1520   ArgVec.reserve(IdxList.size()+1);
1521   ArgVec.push_back(C);
1522   for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
1523     ArgVec.push_back(cast<Constant>(IdxList[i]));
1524   const ExprMapKeyType &Key = std::make_pair(Instruction::GetElementPtr,ArgVec);
1525   return ExprConstants.getOrCreate(ReqTy, Key);
1526 }
1527
1528 Constant *ConstantExpr::getGetElementPtr(Constant *C,
1529                                          const std::vector<Constant*> &IdxList){
1530   // Get the result type of the getelementptr!
1531   std::vector<Value*> VIdxList(IdxList.begin(), IdxList.end());
1532
1533   const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), VIdxList,
1534                                                      true);
1535   assert(Ty && "GEP indices invalid!");
1536   return getGetElementPtrTy(PointerType::get(Ty), C, VIdxList);
1537 }
1538
1539 Constant *ConstantExpr::getGetElementPtr(Constant *C,
1540                                          const std::vector<Value*> &IdxList) {
1541   // Get the result type of the getelementptr!
1542   const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
1543                                                      true);
1544   assert(Ty && "GEP indices invalid!");
1545   return getGetElementPtrTy(PointerType::get(Ty), C, IdxList);
1546 }
1547
1548 Constant *ConstantExpr::getExtractElementTy(const Type *ReqTy, Constant *Val,
1549                                             Constant *Idx) {
1550   if (Constant *FC = ConstantFoldExtractElementInstruction(Val, Idx))
1551     return FC;          // Fold a few common cases...
1552   // Look up the constant in the table first to ensure uniqueness
1553   std::vector<Constant*> ArgVec(1, Val);
1554   ArgVec.push_back(Idx);
1555   const ExprMapKeyType &Key = std::make_pair(Instruction::ExtractElement,ArgVec);
1556   return ExprConstants.getOrCreate(ReqTy, Key);
1557 }
1558
1559 Constant *ConstantExpr::getExtractElement(Constant *Val, Constant *Idx) {
1560   assert(isa<PackedType>(Val->getType()) &&
1561          "Tried to create extractelement operation on non-packed type!");
1562   assert(Idx->getType() == Type::UIntTy &&
1563          "Extractelement index must be uint type!");
1564   return getExtractElementTy(cast<PackedType>(Val->getType())->getElementType(),
1565                              Val, Idx);
1566 }
1567
1568 Constant *ConstantExpr::getInsertElementTy(const Type *ReqTy, Constant *Val,
1569                                            Constant *Elt, Constant *Idx) {
1570   if (Constant *FC = ConstantFoldInsertElementInstruction(Val, Elt, Idx))
1571     return FC;          // Fold a few common cases...
1572   // Look up the constant in the table first to ensure uniqueness
1573   std::vector<Constant*> ArgVec(1, Val);
1574   ArgVec.push_back(Elt);
1575   ArgVec.push_back(Idx);
1576   const ExprMapKeyType &Key = std::make_pair(Instruction::InsertElement,ArgVec);
1577   return ExprConstants.getOrCreate(ReqTy, Key);
1578 }
1579
1580 Constant *ConstantExpr::getInsertElement(Constant *Val, Constant *Elt,
1581                                          Constant *Idx) {
1582   assert(isa<PackedType>(Val->getType()) &&
1583          "Tried to create insertelement operation on non-packed type!");
1584   assert(Elt->getType() == cast<PackedType>(Val->getType())->getElementType()
1585          && "Insertelement types must match!");
1586   assert(Idx->getType() == Type::UIntTy &&
1587          "Insertelement index must be uint type!");
1588   return getInsertElementTy(cast<PackedType>(Val->getType())->getElementType(),
1589                             Val, Elt, Idx);
1590 }
1591
1592 Constant *ConstantExpr::getShuffleVectorTy(const Type *ReqTy, Constant *V1,
1593                                            Constant *V2, Constant *Mask) {
1594   if (Constant *FC = ConstantFoldShuffleVectorInstruction(V1, V2, Mask))
1595     return FC;          // Fold a few common cases...
1596   // Look up the constant in the table first to ensure uniqueness
1597   std::vector<Constant*> ArgVec(1, V1);
1598   ArgVec.push_back(V2);
1599   ArgVec.push_back(Mask);
1600   const ExprMapKeyType &Key = std::make_pair(Instruction::ShuffleVector,ArgVec);
1601   return ExprConstants.getOrCreate(ReqTy, Key);
1602 }
1603
1604 Constant *ConstantExpr::getShuffleVector(Constant *V1, Constant *V2,
1605                                          Constant *Mask) {
1606   assert(ShuffleVectorInst::isValidOperands(V1, V2, Mask) &&
1607          "Invalid shuffle vector constant expr operands!");
1608   return getShuffleVectorTy(V1->getType(), V1, V2, Mask);
1609 }
1610
1611
1612 // destroyConstant - Remove the constant from the constant table...
1613 //
1614 void ConstantExpr::destroyConstant() {
1615   ExprConstants.remove(this);
1616   destroyConstantImpl();
1617 }
1618
1619 const char *ConstantExpr::getOpcodeName() const {
1620   return Instruction::getOpcodeName(getOpcode());
1621 }
1622
1623 //===----------------------------------------------------------------------===//
1624 //                replaceUsesOfWithOnConstant implementations
1625
1626 void ConstantArray::replaceUsesOfWithOnConstant(Value *From, Value *To,
1627                                                 Use *U) {
1628   assert(isa<Constant>(To) && "Cannot make Constant refer to non-constant!");
1629   Constant *ToC = cast<Constant>(To);
1630
1631   unsigned OperandToUpdate = U-OperandList;
1632   assert(getOperand(OperandToUpdate) == From && "ReplaceAllUsesWith broken!");
1633
1634   std::pair<ArrayConstantsTy::MapKey, Constant*> Lookup;
1635   Lookup.first.first = getType();
1636   Lookup.second = this;
1637
1638   std::vector<Constant*> &Values = Lookup.first.second;
1639   Values.reserve(getNumOperands());  // Build replacement array.
1640
1641   // Fill values with the modified operands of the constant array.  Also,
1642   // compute whether this turns into an all-zeros array.
1643   bool isAllZeros = false;
1644   if (!ToC->isNullValue()) {
1645     for (Use *O = OperandList, *E = OperandList+getNumOperands(); O != E; ++O)
1646       Values.push_back(cast<Constant>(O->get()));
1647   } else {
1648     isAllZeros = true;
1649     for (Use *O = OperandList, *E = OperandList+getNumOperands(); O != E; ++O) {
1650       Constant *Val = cast<Constant>(O->get());
1651       Values.push_back(Val);
1652       if (isAllZeros) isAllZeros = Val->isNullValue();
1653     }
1654   }
1655   Values[OperandToUpdate] = ToC;
1656
1657   Constant *Replacement = 0;
1658   if (isAllZeros) {
1659     Replacement = ConstantAggregateZero::get(getType());
1660   } else {
1661     // Check to see if we have this array type already.
1662     bool Exists;
1663     ArrayConstantsTy::MapTy::iterator I =
1664       ArrayConstants.InsertOrGetItem(Lookup, Exists);
1665
1666     if (Exists) {
1667       Replacement = I->second;
1668     } else {
1669       // Okay, the new shape doesn't exist in the system yet.  Instead of
1670       // creating a new constant array, inserting it, replaceallusesof'ing the
1671       // old with the new, then deleting the old... just update the current one
1672       // in place!
1673       ArrayConstants.MoveConstantToNewSlot(this, I);
1674
1675       // Update to the new value.
1676       setOperand(OperandToUpdate, ToC);
1677       return;
1678     }
1679   }
1680
1681   // Otherwise, I do need to replace this with an existing value.
1682   assert(Replacement != this && "I didn't contain From!");
1683
1684   // Everyone using this now uses the replacement.
1685   uncheckedReplaceAllUsesWith(Replacement);
1686
1687   // Delete the old constant!
1688   destroyConstant();
1689 }
1690
1691 void ConstantStruct::replaceUsesOfWithOnConstant(Value *From, Value *To,
1692                                                  Use *U) {
1693   assert(isa<Constant>(To) && "Cannot make Constant refer to non-constant!");
1694   Constant *ToC = cast<Constant>(To);
1695
1696   unsigned OperandToUpdate = U-OperandList;
1697   assert(getOperand(OperandToUpdate) == From && "ReplaceAllUsesWith broken!");
1698
1699   std::pair<StructConstantsTy::MapKey, Constant*> Lookup;
1700   Lookup.first.first = getType();
1701   Lookup.second = this;
1702   std::vector<Constant*> &Values = Lookup.first.second;
1703   Values.reserve(getNumOperands());  // Build replacement struct.
1704
1705
1706   // Fill values with the modified operands of the constant struct.  Also,
1707   // compute whether this turns into an all-zeros struct.
1708   bool isAllZeros = false;
1709   if (!ToC->isNullValue()) {
1710     for (Use *O = OperandList, *E = OperandList+getNumOperands(); O != E; ++O)
1711       Values.push_back(cast<Constant>(O->get()));
1712   } else {
1713     isAllZeros = true;
1714     for (Use *O = OperandList, *E = OperandList+getNumOperands(); O != E; ++O) {
1715       Constant *Val = cast<Constant>(O->get());
1716       Values.push_back(Val);
1717       if (isAllZeros) isAllZeros = Val->isNullValue();
1718     }
1719   }
1720   Values[OperandToUpdate] = ToC;
1721
1722   Constant *Replacement = 0;
1723   if (isAllZeros) {
1724     Replacement = ConstantAggregateZero::get(getType());
1725   } else {
1726     // Check to see if we have this array type already.
1727     bool Exists;
1728     StructConstantsTy::MapTy::iterator I =
1729       StructConstants.InsertOrGetItem(Lookup, Exists);
1730
1731     if (Exists) {
1732       Replacement = I->second;
1733     } else {
1734       // Okay, the new shape doesn't exist in the system yet.  Instead of
1735       // creating a new constant struct, inserting it, replaceallusesof'ing the
1736       // old with the new, then deleting the old... just update the current one
1737       // in place!
1738       StructConstants.MoveConstantToNewSlot(this, I);
1739
1740       // Update to the new value.
1741       setOperand(OperandToUpdate, ToC);
1742       return;
1743     }
1744   }
1745
1746   assert(Replacement != this && "I didn't contain From!");
1747
1748   // Everyone using this now uses the replacement.
1749   uncheckedReplaceAllUsesWith(Replacement);
1750
1751   // Delete the old constant!
1752   destroyConstant();
1753 }
1754
1755 void ConstantPacked::replaceUsesOfWithOnConstant(Value *From, Value *To,
1756                                                  Use *U) {
1757   assert(isa<Constant>(To) && "Cannot make Constant refer to non-constant!");
1758
1759   std::vector<Constant*> Values;
1760   Values.reserve(getNumOperands());  // Build replacement array...
1761   for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
1762     Constant *Val = getOperand(i);
1763     if (Val == From) Val = cast<Constant>(To);
1764     Values.push_back(Val);
1765   }
1766
1767   Constant *Replacement = ConstantPacked::get(getType(), Values);
1768   assert(Replacement != this && "I didn't contain From!");
1769
1770   // Everyone using this now uses the replacement.
1771   uncheckedReplaceAllUsesWith(Replacement);
1772
1773   // Delete the old constant!
1774   destroyConstant();
1775 }
1776
1777 void ConstantExpr::replaceUsesOfWithOnConstant(Value *From, Value *ToV,
1778                                                Use *U) {
1779   assert(isa<Constant>(ToV) && "Cannot make Constant refer to non-constant!");
1780   Constant *To = cast<Constant>(ToV);
1781
1782   Constant *Replacement = 0;
1783   if (getOpcode() == Instruction::GetElementPtr) {
1784     std::vector<Constant*> Indices;
1785     Constant *Pointer = getOperand(0);
1786     Indices.reserve(getNumOperands()-1);
1787     if (Pointer == From) Pointer = To;
1788
1789     for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
1790       Constant *Val = getOperand(i);
1791       if (Val == From) Val = To;
1792       Indices.push_back(Val);
1793     }
1794     Replacement = ConstantExpr::getGetElementPtr(Pointer, Indices);
1795   } else if (getOpcode() == Instruction::Cast) {
1796     assert(getOperand(0) == From && "Cast only has one use!");
1797     Replacement = ConstantExpr::getCast(To, getType());
1798   } else if (getOpcode() == Instruction::Select) {
1799     Constant *C1 = getOperand(0);
1800     Constant *C2 = getOperand(1);
1801     Constant *C3 = getOperand(2);
1802     if (C1 == From) C1 = To;
1803     if (C2 == From) C2 = To;
1804     if (C3 == From) C3 = To;
1805     Replacement = ConstantExpr::getSelect(C1, C2, C3);
1806   } else if (getOpcode() == Instruction::ExtractElement) {
1807     Constant *C1 = getOperand(0);
1808     Constant *C2 = getOperand(1);
1809     if (C1 == From) C1 = To;
1810     if (C2 == From) C2 = To;
1811     Replacement = ConstantExpr::getExtractElement(C1, C2);
1812   } else if (getOpcode() == Instruction::InsertElement) {
1813     Constant *C1 = getOperand(0);
1814     Constant *C2 = getOperand(1);
1815     Constant *C3 = getOperand(1);
1816     if (C1 == From) C1 = To;
1817     if (C2 == From) C2 = To;
1818     if (C3 == From) C3 = To;
1819     Replacement = ConstantExpr::getInsertElement(C1, C2, C3);
1820   } else if (getOpcode() == Instruction::ShuffleVector) {
1821     Constant *C1 = getOperand(0);
1822     Constant *C2 = getOperand(1);
1823     Constant *C3 = getOperand(2);
1824     if (C1 == From) C1 = To;
1825     if (C2 == From) C2 = To;
1826     if (C3 == From) C3 = To;
1827     Replacement = ConstantExpr::getShuffleVector(C1, C2, C3);
1828   } else if (getNumOperands() == 2) {
1829     Constant *C1 = getOperand(0);
1830     Constant *C2 = getOperand(1);
1831     if (C1 == From) C1 = To;
1832     if (C2 == From) C2 = To;
1833     Replacement = ConstantExpr::get(getOpcode(), C1, C2);
1834   } else {
1835     assert(0 && "Unknown ConstantExpr type!");
1836     return;
1837   }
1838
1839   assert(Replacement != this && "I didn't contain From!");
1840
1841   // Everyone using this now uses the replacement.
1842   uncheckedReplaceAllUsesWith(Replacement);
1843
1844   // Delete the old constant!
1845   destroyConstant();
1846 }
1847
1848
1849
1850 /// clearAllValueMaps - This method frees all internal memory used by the
1851 /// constant subsystem, which can be used in environments where this memory
1852 /// is otherwise reported as a leak.
1853 void Constant::clearAllValueMaps() {
1854   std::vector<Constant *> Constants;
1855
1856   DoubleConstants.clear(Constants);
1857   FloatConstants.clear(Constants);
1858   SIntConstants.clear(Constants);
1859   UIntConstants.clear(Constants);
1860   AggZeroConstants.clear(Constants);
1861   ArrayConstants.clear(Constants);
1862   StructConstants.clear(Constants);
1863   PackedConstants.clear(Constants);
1864   NullPtrConstants.clear(Constants);
1865   UndefValueConstants.clear(Constants);
1866   ExprConstants.clear(Constants);
1867
1868   for (std::vector<Constant *>::iterator I = Constants.begin(),
1869        E = Constants.end(); I != E; ++I)
1870     (*I)->dropAllReferences();
1871   for (std::vector<Constant *>::iterator I = Constants.begin(),
1872        E = Constants.end(); I != E; ++I)
1873     (*I)->destroyConstantImpl();
1874   Constants.clear();
1875 }
1876
1877 /// getStringValue - Turn an LLVM constant pointer that eventually points to a
1878 /// global into a string value.  Return an empty string if we can't do it.
1879 /// Parameter Chop determines if the result is chopped at the first null
1880 /// terminator.
1881 ///
1882 std::string Constant::getStringValue(bool Chop, unsigned Offset) {
1883   if (GlobalVariable *GV = dyn_cast<GlobalVariable>(this)) {
1884     if (GV->hasInitializer() && isa<ConstantArray>(GV->getInitializer())) {
1885       ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
1886       if (Init->isString()) {
1887         std::string Result = Init->getAsString();
1888         if (Offset < Result.size()) {
1889           // If we are pointing INTO The string, erase the beginning...
1890           Result.erase(Result.begin(), Result.begin()+Offset);
1891
1892           // Take off the null terminator, and any string fragments after it.
1893           if (Chop) {
1894             std::string::size_type NullPos = Result.find_first_of((char)0);
1895             if (NullPos != std::string::npos)
1896               Result.erase(Result.begin()+NullPos, Result.end());
1897           }
1898           return Result;
1899         }
1900       }
1901     }
1902   } else if (Constant *C = dyn_cast<Constant>(this)) {
1903     if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
1904       return GV->getStringValue(Chop, Offset);
1905     else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1906       if (CE->getOpcode() == Instruction::GetElementPtr) {
1907         // Turn a gep into the specified offset.
1908         if (CE->getNumOperands() == 3 &&
1909             cast<Constant>(CE->getOperand(1))->isNullValue() &&
1910             isa<ConstantInt>(CE->getOperand(2))) {
1911           Offset += cast<ConstantInt>(CE->getOperand(2))->getRawValue();
1912           return CE->getOperand(0)->getStringValue(Chop, Offset);
1913         }
1914       }
1915     }
1916   }
1917   return "";
1918 }
1919