BitcodeReader.cpp revision 07d98b4afbdcbb4eed048400d9116de1ec83e866 
1//===- BitcodeReader.cpp - Internal BitcodeReader implementation ----------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by Chris Lattner and is distributed under
6// the University of Illinois Open Source License.  See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This header defines the BitcodeReader class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "BitcodeReader.h"
15#include "llvm/Bitcode/BitstreamReader.h"
16#include "llvm/Constants.h"
17#include "llvm/DerivedTypes.h"
18#include "llvm/Module.h"
19#include "llvm/ADT/SmallString.h"
20#include "llvm/Support/MathExtras.h"
21using namespace llvm;
22
23/// ConvertToString - Convert a string from a record into an std::string, return
24/// true on failure.
25template<typename StrTy>
26static bool ConvertToString(SmallVector<uint64_t, 64> &Record, unsigned Idx,
27                            StrTy &Result) {
28  if (Record.size() < Idx+1 || Record.size() < Record[Idx]+Idx+1)
29    return true;
30
31  for (unsigned i = 0, e = Record[Idx]; i != e; ++i)
32    Result += (char)Record[Idx+i+1];
33  return false;
34}
35
36static GlobalValue::LinkageTypes GetDecodedLinkage(unsigned Val) {
37  switch (Val) {
38  default: // Map unknown/new linkages to external
39  case 0: return GlobalValue::ExternalLinkage;
40  case 1: return GlobalValue::WeakLinkage;
41  case 2: return GlobalValue::AppendingLinkage;
42  case 3: return GlobalValue::InternalLinkage;
43  case 4: return GlobalValue::LinkOnceLinkage;
44  case 5: return GlobalValue::DLLImportLinkage;
45  case 6: return GlobalValue::DLLExportLinkage;
46  case 7: return GlobalValue::ExternalWeakLinkage;
47  }
48}
49
50static GlobalValue::VisibilityTypes GetDecodedVisibility(unsigned Val) {
51  switch (Val) {
52  default: // Map unknown visibilities to default.
53  case 0: return GlobalValue::DefaultVisibility;
54  case 1: return GlobalValue::HiddenVisibility;
55  }
56}
57
58static int GetDecodedCastOpcode(unsigned Val) {
59  switch (Val) {
60  default: return -1;
61  case bitc::CAST_TRUNC   : return Instruction::Trunc;
62  case bitc::CAST_ZEXT    : return Instruction::ZExt;
63  case bitc::CAST_SEXT    : return Instruction::SExt;
64  case bitc::CAST_FPTOUI  : return Instruction::FPToUI;
65  case bitc::CAST_FPTOSI  : return Instruction::FPToSI;
66  case bitc::CAST_UITOFP  : return Instruction::UIToFP;
67  case bitc::CAST_SITOFP  : return Instruction::SIToFP;
68  case bitc::CAST_FPTRUNC : return Instruction::FPTrunc;
69  case bitc::CAST_FPEXT   : return Instruction::FPExt;
70  case bitc::CAST_PTRTOINT: return Instruction::PtrToInt;
71  case bitc::CAST_INTTOPTR: return Instruction::IntToPtr;
72  case bitc::CAST_BITCAST : return Instruction::BitCast;
73  }
74}
75static int GetDecodedBinaryOpcode(unsigned Val, const Type *Ty) {
76  switch (Val) {
77  default: return -1;
78  case bitc::BINOP_ADD:  return Instruction::Add;
79  case bitc::BINOP_SUB:  return Instruction::Sub;
80  case bitc::BINOP_MUL:  return Instruction::Mul;
81  case bitc::BINOP_UDIV: return Instruction::UDiv;
82  case bitc::BINOP_SDIV:
83    return Ty->isFPOrFPVector() ? Instruction::FDiv : Instruction::SDiv;
84  case bitc::BINOP_UREM: return Instruction::URem;
85  case bitc::BINOP_SREM:
86    return Ty->isFPOrFPVector() ? Instruction::FRem : Instruction::SRem;
87  case bitc::BINOP_SHL:  return Instruction::Shl;
88  case bitc::BINOP_LSHR: return Instruction::LShr;
89  case bitc::BINOP_ASHR: return Instruction::AShr;
90  case bitc::BINOP_AND:  return Instruction::And;
91  case bitc::BINOP_OR:   return Instruction::Or;
92  case bitc::BINOP_XOR:  return Instruction::Xor;
93  }
94}
95
96
97namespace {
98  /// @brief A class for maintaining the slot number definition
99  /// as a placeholder for the actual definition for forward constants defs.
100  class ConstantPlaceHolder : public ConstantExpr {
101    ConstantPlaceHolder();                       // DO NOT IMPLEMENT
102    void operator=(const ConstantPlaceHolder &); // DO NOT IMPLEMENT
103  public:
104    Use Op;
105    ConstantPlaceHolder(const Type *Ty)
106      : ConstantExpr(Ty, Instruction::UserOp1, &Op, 1),
107        Op(UndefValue::get(Type::Int32Ty), this) {
108    }
109  };
110}
111
112Constant *BitcodeReaderValueList::getConstantFwdRef(unsigned Idx,
113                                                    const Type *Ty) {
114  if (Idx >= size()) {
115    // Insert a bunch of null values.
116    Uses.resize(Idx+1);
117    OperandList = &Uses[0];
118    NumOperands = Idx+1;
119  }
120
121  if (Uses[Idx]) {
122    assert(Ty == getOperand(Idx)->getType() &&
123           "Type mismatch in constant table!");
124    return cast<Constant>(getOperand(Idx));
125  }
126
127  // Create and return a placeholder, which will later be RAUW'd.
128  Constant *C = new ConstantPlaceHolder(Ty);
129  Uses[Idx].init(C, this);
130  return C;
131}
132
133
134const Type *BitcodeReader::getTypeByID(unsigned ID, bool isTypeTable) {
135  // If the TypeID is in range, return it.
136  if (ID < TypeList.size())
137    return TypeList[ID].get();
138  if (!isTypeTable) return 0;
139
140  // The type table allows forward references.  Push as many Opaque types as
141  // needed to get up to ID.
142  while (TypeList.size() <= ID)
143    TypeList.push_back(OpaqueType::get());
144  return TypeList.back().get();
145}
146
147
148bool BitcodeReader::ParseTypeTable(BitstreamReader &Stream) {
149  if (Stream.EnterSubBlock())
150    return Error("Malformed block record");
151
152  if (!TypeList.empty())
153    return Error("Multiple TYPE_BLOCKs found!");
154
155  SmallVector<uint64_t, 64> Record;
156  unsigned NumRecords = 0;
157
158  // Read all the records for this type table.
159  while (1) {
160    unsigned Code = Stream.ReadCode();
161    if (Code == bitc::END_BLOCK) {
162      if (NumRecords != TypeList.size())
163        return Error("Invalid type forward reference in TYPE_BLOCK");
164      if (Stream.ReadBlockEnd())
165        return Error("Error at end of type table block");
166      return false;
167    }
168
169    if (Code == bitc::ENTER_SUBBLOCK) {
170      // No known subblocks, always skip them.
171      Stream.ReadSubBlockID();
172      if (Stream.SkipBlock())
173        return Error("Malformed block record");
174      continue;
175    }
176
177    if (Code == bitc::DEFINE_ABBREV) {
178      Stream.ReadAbbrevRecord();
179      continue;
180    }
181
182    // Read a record.
183    Record.clear();
184    const Type *ResultTy = 0;
185    switch (Stream.ReadRecord(Code, Record)) {
186    default:  // Default behavior: unknown type.
187      ResultTy = 0;
188      break;
189    case bitc::TYPE_CODE_NUMENTRY: // TYPE_CODE_NUMENTRY: [numentries]
190      // TYPE_CODE_NUMENTRY contains a count of the number of types in the
191      // type list.  This allows us to reserve space.
192      if (Record.size() < 1)
193        return Error("Invalid TYPE_CODE_NUMENTRY record");
194      TypeList.reserve(Record[0]);
195      continue;
196    case bitc::TYPE_CODE_META:      // TYPE_CODE_META: [metacode]...
197      // No metadata supported yet.
198      if (Record.size() < 1)
199        return Error("Invalid TYPE_CODE_META record");
200      continue;
201
202    case bitc::TYPE_CODE_VOID:      // VOID
203      ResultTy = Type::VoidTy;
204      break;
205    case bitc::TYPE_CODE_FLOAT:     // FLOAT
206      ResultTy = Type::FloatTy;
207      break;
208    case bitc::TYPE_CODE_DOUBLE:    // DOUBLE
209      ResultTy = Type::DoubleTy;
210      break;
211    case bitc::TYPE_CODE_LABEL:     // LABEL
212      ResultTy = Type::LabelTy;
213      break;
214    case bitc::TYPE_CODE_OPAQUE:    // OPAQUE
215      ResultTy = 0;
216      break;
217    case bitc::TYPE_CODE_INTEGER:   // INTEGER: [width]
218      if (Record.size() < 1)
219        return Error("Invalid Integer type record");
220
221      ResultTy = IntegerType::get(Record[0]);
222      break;
223    case bitc::TYPE_CODE_POINTER:   // POINTER: [pointee type]
224      if (Record.size() < 1)
225        return Error("Invalid POINTER type record");
226      ResultTy = PointerType::get(getTypeByID(Record[0], true));
227      break;
228    case bitc::TYPE_CODE_FUNCTION: {
229      // FUNCTION: [vararg, retty, #pararms, paramty N]
230      if (Record.size() < 3 || Record.size() < Record[2]+3)
231        return Error("Invalid FUNCTION type record");
232      std::vector<const Type*> ArgTys;
233      for (unsigned i = 0, e = Record[2]; i != e; ++i)
234        ArgTys.push_back(getTypeByID(Record[3+i], true));
235
236      // FIXME: PARAM TYS.
237      ResultTy = FunctionType::get(getTypeByID(Record[1], true), ArgTys,
238                                   Record[0]);
239      break;
240    }
241    case bitc::TYPE_CODE_STRUCT: {  // STRUCT: [ispacked, #elts, eltty x N]
242      if (Record.size() < 2 || Record.size() < Record[1]+2)
243        return Error("Invalid STRUCT type record");
244      std::vector<const Type*> EltTys;
245      for (unsigned i = 0, e = Record[1]; i != e; ++i)
246        EltTys.push_back(getTypeByID(Record[2+i], true));
247      ResultTy = StructType::get(EltTys, Record[0]);
248      break;
249    }
250    case bitc::TYPE_CODE_ARRAY:     // ARRAY: [numelts, eltty]
251      if (Record.size() < 2)
252        return Error("Invalid ARRAY type record");
253      ResultTy = ArrayType::get(getTypeByID(Record[1], true), Record[0]);
254      break;
255    case bitc::TYPE_CODE_VECTOR:    // VECTOR: [numelts, eltty]
256      if (Record.size() < 2)
257        return Error("Invalid VECTOR type record");
258      ResultTy = VectorType::get(getTypeByID(Record[1], true), Record[0]);
259      break;
260    }
261
262    if (NumRecords == TypeList.size()) {
263      // If this is a new type slot, just append it.
264      TypeList.push_back(ResultTy ? ResultTy : OpaqueType::get());
265      ++NumRecords;
266    } else if (ResultTy == 0) {
267      // Otherwise, this was forward referenced, so an opaque type was created,
268      // but the result type is actually just an opaque.  Leave the one we
269      // created previously.
270      ++NumRecords;
271    } else {
272      // Otherwise, this was forward referenced, so an opaque type was created.
273      // Resolve the opaque type to the real type now.
274      assert(NumRecords < TypeList.size() && "Typelist imbalance");
275      const OpaqueType *OldTy = cast<OpaqueType>(TypeList[NumRecords++].get());
276
277      // Don't directly push the new type on the Tab. Instead we want to replace
278      // the opaque type we previously inserted with the new concrete value. The
279      // refinement from the abstract (opaque) type to the new type causes all
280      // uses of the abstract type to use the concrete type (NewTy). This will
281      // also cause the opaque type to be deleted.
282      const_cast<OpaqueType*>(OldTy)->refineAbstractTypeTo(ResultTy);
283
284      // This should have replaced the old opaque type with the new type in the
285      // value table... or with a preexisting type that was already in the
286      // system.  Let's just make sure it did.
287      assert(TypeList[NumRecords-1].get() != OldTy &&
288             "refineAbstractType didn't work!");
289    }
290  }
291}
292
293
294bool BitcodeReader::ParseTypeSymbolTable(BitstreamReader &Stream) {
295  if (Stream.EnterSubBlock())
296    return Error("Malformed block record");
297
298  SmallVector<uint64_t, 64> Record;
299
300  // Read all the records for this type table.
301  std::string TypeName;
302  while (1) {
303    unsigned Code = Stream.ReadCode();
304    if (Code == bitc::END_BLOCK) {
305      if (Stream.ReadBlockEnd())
306        return Error("Error at end of type symbol table block");
307      return false;
308    }
309
310    if (Code == bitc::ENTER_SUBBLOCK) {
311      // No known subblocks, always skip them.
312      Stream.ReadSubBlockID();
313      if (Stream.SkipBlock())
314        return Error("Malformed block record");
315      continue;
316    }
317
318    if (Code == bitc::DEFINE_ABBREV) {
319      Stream.ReadAbbrevRecord();
320      continue;
321    }
322
323    // Read a record.
324    Record.clear();
325    switch (Stream.ReadRecord(Code, Record)) {
326    default:  // Default behavior: unknown type.
327      break;
328    case bitc::TST_CODE_ENTRY:    // TST_ENTRY: [typeid, namelen, namechar x N]
329      if (ConvertToString(Record, 1, TypeName))
330        return Error("Invalid TST_ENTRY record");
331      unsigned TypeID = Record[0];
332      if (TypeID >= TypeList.size())
333        return Error("Invalid Type ID in TST_ENTRY record");
334
335      TheModule->addTypeName(TypeName, TypeList[TypeID].get());
336      TypeName.clear();
337      break;
338    }
339  }
340}
341
342bool BitcodeReader::ParseValueSymbolTable(BitstreamReader &Stream) {
343  if (Stream.EnterSubBlock())
344    return Error("Malformed block record");
345
346  SmallVector<uint64_t, 64> Record;
347
348  // Read all the records for this value table.
349  SmallString<128> ValueName;
350  while (1) {
351    unsigned Code = Stream.ReadCode();
352    if (Code == bitc::END_BLOCK) {
353      if (Stream.ReadBlockEnd())
354        return Error("Error at end of value symbol table block");
355      return false;
356    }
357    if (Code == bitc::ENTER_SUBBLOCK) {
358      // No known subblocks, always skip them.
359      Stream.ReadSubBlockID();
360      if (Stream.SkipBlock())
361        return Error("Malformed block record");
362      continue;
363    }
364
365    if (Code == bitc::DEFINE_ABBREV) {
366      Stream.ReadAbbrevRecord();
367      continue;
368    }
369
370    // Read a record.
371    Record.clear();
372    switch (Stream.ReadRecord(Code, Record)) {
373    default:  // Default behavior: unknown type.
374      break;
375    case bitc::TST_CODE_ENTRY:    // VST_ENTRY: [valueid, namelen, namechar x N]
376      if (ConvertToString(Record, 1, ValueName))
377        return Error("Invalid TST_ENTRY record");
378      unsigned ValueID = Record[0];
379      if (ValueID >= ValueList.size())
380        return Error("Invalid Value ID in VST_ENTRY record");
381      Value *V = ValueList[ValueID];
382
383      V->setName(&ValueName[0], ValueName.size());
384      ValueName.clear();
385      break;
386    }
387  }
388}
389
390/// DecodeSignRotatedValue - Decode a signed value stored with the sign bit in
391/// the LSB for dense VBR encoding.
392static uint64_t DecodeSignRotatedValue(uint64_t V) {
393  if ((V & 1) == 0)
394    return V >> 1;
395  if (V != 1)
396    return -(V >> 1);
397  // There is no such thing as -0 with integers.  "-0" really means MININT.
398  return 1ULL << 63;
399}
400
401/// ResolveGlobalAndAliasInits - Resolve all of the initializers for global
402/// values and aliases that we can.
403bool BitcodeReader::ResolveGlobalAndAliasInits() {
404  std::vector<std::pair<GlobalVariable*, unsigned> > GlobalInitWorklist;
405  std::vector<std::pair<GlobalAlias*, unsigned> > AliasInitWorklist;
406
407  GlobalInitWorklist.swap(GlobalInits);
408  AliasInitWorklist.swap(AliasInits);
409
410  while (!GlobalInitWorklist.empty()) {
411    unsigned ValID = GlobalInits.back().second;
412    if (ValID >= ValueList.size()) {
413      // Not ready to resolve this yet, it requires something later in the file.
414      GlobalInitWorklist.push_back(GlobalInits.back());
415    } else {
416      if (Constant *C = dyn_cast<Constant>(ValueList[ValID]))
417        GlobalInitWorklist.back().first->setInitializer(C);
418      else
419        return Error("Global variable initializer is not a constant!");
420    }
421    GlobalInitWorklist.pop_back();
422  }
423
424  while (!AliasInitWorklist.empty()) {
425    unsigned ValID = AliasInitWorklist.back().second;
426    if (ValID >= ValueList.size()) {
427      AliasInits.push_back(AliasInitWorklist.back());
428    } else {
429      if (Constant *C = dyn_cast<Constant>(ValueList[ValID]))
430        AliasInitWorklist.back().first->setAliasee(
431                                            // FIXME:
432                                            cast<GlobalValue>(C));
433      else
434        return Error("Alias initializer is not a constant!");
435    }
436    AliasInitWorklist.pop_back();
437  }
438  return false;
439}
440
441
442bool BitcodeReader::ParseConstants(BitstreamReader &Stream) {
443  if (Stream.EnterSubBlock())
444    return Error("Malformed block record");
445
446  SmallVector<uint64_t, 64> Record;
447
448  // Read all the records for this value table.
449  const Type *CurTy = Type::Int32Ty;
450  unsigned NextCstNo = ValueList.size();
451  while (1) {
452    unsigned Code = Stream.ReadCode();
453    if (Code == bitc::END_BLOCK) {
454      if (NextCstNo != ValueList.size())
455        return Error("Invalid constant reference!");
456
457      if (Stream.ReadBlockEnd())
458        return Error("Error at end of constants block");
459      return false;
460    }
461
462    if (Code == bitc::ENTER_SUBBLOCK) {
463      // No known subblocks, always skip them.
464      Stream.ReadSubBlockID();
465      if (Stream.SkipBlock())
466        return Error("Malformed block record");
467      continue;
468    }
469
470    if (Code == bitc::DEFINE_ABBREV) {
471      Stream.ReadAbbrevRecord();
472      continue;
473    }
474
475    // Read a record.
476    Record.clear();
477    Value *V = 0;
478    switch (Stream.ReadRecord(Code, Record)) {
479    default:  // Default behavior: unknown constant
480    case bitc::CST_CODE_UNDEF:     // UNDEF
481      V = UndefValue::get(CurTy);
482      break;
483    case bitc::CST_CODE_SETTYPE:   // SETTYPE: [typeid]
484      if (Record.empty())
485        return Error("Malformed CST_SETTYPE record");
486      if (Record[0] >= TypeList.size())
487        return Error("Invalid Type ID in CST_SETTYPE record");
488      CurTy = TypeList[Record[0]];
489      continue;  // Skip the ValueList manipulation.
490    case bitc::CST_CODE_NULL:      // NULL
491      V = Constant::getNullValue(CurTy);
492      break;
493    case bitc::CST_CODE_INTEGER:   // INTEGER: [intval]
494      if (!isa<IntegerType>(CurTy) || Record.empty())
495        return Error("Invalid CST_INTEGER record");
496      V = ConstantInt::get(CurTy, DecodeSignRotatedValue(Record[0]));
497      break;
498    case bitc::CST_CODE_WIDE_INTEGER: {// WIDE_INTEGER: [n, n x intval]
499      if (!isa<IntegerType>(CurTy) || Record.empty() ||
500          Record.size() < Record[0]+1)
501        return Error("Invalid WIDE_INTEGER record");
502
503      unsigned NumWords = Record[0];
504      SmallVector<uint64_t, 8> Words;
505      Words.resize(NumWords);
506      for (unsigned i = 0; i != NumWords; ++i)
507        Words[i] = DecodeSignRotatedValue(Record[i+1]);
508      V = ConstantInt::get(APInt(cast<IntegerType>(CurTy)->getBitWidth(),
509                                 NumWords, &Words[0]));
510      break;
511    }
512    case bitc::CST_CODE_FLOAT:     // FLOAT: [fpval]
513      if (Record.empty())
514        return Error("Invalid FLOAT record");
515      if (CurTy == Type::FloatTy)
516        V = ConstantFP::get(CurTy, BitsToFloat(Record[0]));
517      else if (CurTy == Type::DoubleTy)
518        V = ConstantFP::get(CurTy, BitsToDouble(Record[0]));
519      else
520        V = UndefValue::get(CurTy);
521      break;
522
523    case bitc::CST_CODE_AGGREGATE: {// AGGREGATE: [n, n x value number]
524      if (Record.empty() || Record.size() < Record[0]+1)
525        return Error("Invalid CST_AGGREGATE record");
526
527      unsigned Size = Record[0];
528      std::vector<Constant*> Elts;
529
530      if (const StructType *STy = dyn_cast<StructType>(CurTy)) {
531        for (unsigned i = 0; i != Size; ++i)
532          Elts.push_back(ValueList.getConstantFwdRef(Record[i+1],
533                                                     STy->getElementType(i)));
534        V = ConstantStruct::get(STy, Elts);
535      } else if (const ArrayType *ATy = dyn_cast<ArrayType>(CurTy)) {
536        const Type *EltTy = ATy->getElementType();
537        for (unsigned i = 0; i != Size; ++i)
538          Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], EltTy));
539        V = ConstantArray::get(ATy, Elts);
540      } else if (const VectorType *VTy = dyn_cast<VectorType>(CurTy)) {
541        const Type *EltTy = VTy->getElementType();
542        for (unsigned i = 0; i != Size; ++i)
543          Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], EltTy));
544        V = ConstantVector::get(Elts);
545      } else {
546        V = UndefValue::get(CurTy);
547      }
548      break;
549    }
550
551    case bitc::CST_CODE_CE_BINOP: {  // CE_BINOP: [opcode, opval, opval]
552      if (Record.size() < 3) return Error("Invalid CE_BINOP record");
553      int Opc = GetDecodedBinaryOpcode(Record[0], CurTy);
554      if (Opc < 0) {
555        V = UndefValue::get(CurTy);  // Unknown binop.
556      } else {
557        Constant *LHS = ValueList.getConstantFwdRef(Record[1], CurTy);
558        Constant *RHS = ValueList.getConstantFwdRef(Record[2], CurTy);
559        V = ConstantExpr::get(Opc, LHS, RHS);
560      }
561      break;
562    }
563    case bitc::CST_CODE_CE_CAST: {  // CE_CAST: [opcode, opty, opval]
564      if (Record.size() < 3) return Error("Invalid CE_CAST record");
565      int Opc = GetDecodedCastOpcode(Record[0]);
566      if (Opc < 0) {
567        V = UndefValue::get(CurTy);  // Unknown cast.
568      } else {
569        const Type *OpTy = getTypeByID(Record[1]);
570        Constant *Op = ValueList.getConstantFwdRef(Record[2], OpTy);
571        V = ConstantExpr::getCast(Opc, Op, CurTy);
572      }
573      break;
574    }
575    case bitc::CST_CODE_CE_GEP: {  // CE_GEP:        [n x operands]
576      if ((Record.size() & 1) == 0) return Error("Invalid CE_GEP record");
577      SmallVector<Constant*, 16> Elts;
578      for (unsigned i = 1, e = Record.size(); i != e; i += 2) {
579        const Type *ElTy = getTypeByID(Record[i]);
580        if (!ElTy) return Error("Invalid CE_GEP record");
581        Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], ElTy));
582      }
583      V = ConstantExpr::getGetElementPtr(Elts[0], &Elts[1], Elts.size()-1);
584      break;
585    }
586    case bitc::CST_CODE_CE_SELECT:  // CE_SELECT: [opval#, opval#, opval#]
587      if (Record.size() < 3) return Error("Invalid CE_SELECT record");
588      V = ConstantExpr::getSelect(ValueList.getConstantFwdRef(Record[0],
589                                                              Type::Int1Ty),
590                                  ValueList.getConstantFwdRef(Record[1],CurTy),
591                                  ValueList.getConstantFwdRef(Record[2],CurTy));
592      break;
593    case bitc::CST_CODE_CE_EXTRACTELT: { // CE_EXTRACTELT: [opty, opval, opval]
594      if (Record.size() < 3) return Error("Invalid CE_EXTRACTELT record");
595      const VectorType *OpTy =
596        dyn_cast_or_null<VectorType>(getTypeByID(Record[0]));
597      if (OpTy == 0) return Error("Invalid CE_EXTRACTELT record");
598      Constant *Op0 = ValueList.getConstantFwdRef(Record[1], OpTy);
599      Constant *Op1 = ValueList.getConstantFwdRef(Record[2],
600                                                  OpTy->getElementType());
601      V = ConstantExpr::getExtractElement(Op0, Op1);
602      break;
603    }
604    case bitc::CST_CODE_CE_INSERTELT: { // CE_INSERTELT: [opval, opval, opval]
605      const VectorType *OpTy = dyn_cast<VectorType>(CurTy);
606      if (Record.size() < 3 || OpTy == 0)
607        return Error("Invalid CE_INSERTELT record");
608      Constant *Op0 = ValueList.getConstantFwdRef(Record[0], OpTy);
609      Constant *Op1 = ValueList.getConstantFwdRef(Record[1],
610                                                  OpTy->getElementType());
611      Constant *Op2 = ValueList.getConstantFwdRef(Record[2], Type::Int32Ty);
612      V = ConstantExpr::getInsertElement(Op0, Op1, Op2);
613      break;
614    }
615    case bitc::CST_CODE_CE_SHUFFLEVEC: { // CE_SHUFFLEVEC: [opval, opval, opval]
616      const VectorType *OpTy = dyn_cast<VectorType>(CurTy);
617      if (Record.size() < 3 || OpTy == 0)
618        return Error("Invalid CE_INSERTELT record");
619      Constant *Op0 = ValueList.getConstantFwdRef(Record[0], OpTy);
620      Constant *Op1 = ValueList.getConstantFwdRef(Record[1], OpTy);
621      const Type *ShufTy=VectorType::get(Type::Int32Ty, OpTy->getNumElements());
622      Constant *Op2 = ValueList.getConstantFwdRef(Record[2], ShufTy);
623      V = ConstantExpr::getShuffleVector(Op0, Op1, Op2);
624      break;
625    }
626    case bitc::CST_CODE_CE_CMP: {     // CE_CMP: [opty, opval, opval, pred]
627      if (Record.size() < 4) return Error("Invalid CE_CMP record");
628      const Type *OpTy = getTypeByID(Record[0]);
629      if (OpTy == 0) return Error("Invalid CE_CMP record");
630      Constant *Op0 = ValueList.getConstantFwdRef(Record[1], OpTy);
631      Constant *Op1 = ValueList.getConstantFwdRef(Record[2], OpTy);
632
633      if (OpTy->isFloatingPoint())
634        V = ConstantExpr::getFCmp(Record[3], Op0, Op1);
635      else
636        V = ConstantExpr::getICmp(Record[3], Op0, Op1);
637      break;
638    }
639    }
640
641    if (NextCstNo == ValueList.size())
642      ValueList.push_back(V);
643    else if (ValueList[NextCstNo] == 0)
644      ValueList.initVal(NextCstNo, V);
645    else {
646      // If there was a forward reference to this constant,
647      Value *OldV = ValueList[NextCstNo];
648      ValueList.setOperand(NextCstNo, V);
649      OldV->replaceAllUsesWith(V);
650      delete OldV;
651    }
652
653    ++NextCstNo;
654  }
655}
656
657bool BitcodeReader::ParseModule(BitstreamReader &Stream,
658                                const std::string &ModuleID) {
659  // Reject multiple MODULE_BLOCK's in a single bitstream.
660  if (TheModule)
661    return Error("Multiple MODULE_BLOCKs in same stream");
662
663  if (Stream.EnterSubBlock())
664    return Error("Malformed block record");
665
666  // Otherwise, create the module.
667  TheModule = new Module(ModuleID);
668
669  SmallVector<uint64_t, 64> Record;
670  std::vector<std::string> SectionTable;
671
672  // Read all the records for this module.
673  while (!Stream.AtEndOfStream()) {
674    unsigned Code = Stream.ReadCode();
675    if (Code == bitc::END_BLOCK) {
676      ResolveGlobalAndAliasInits();
677      if (!GlobalInits.empty() || !AliasInits.empty())
678        return Error("Malformed global initializer set");
679      if (Stream.ReadBlockEnd())
680        return Error("Error at end of module block");
681      return false;
682    }
683
684    if (Code == bitc::ENTER_SUBBLOCK) {
685      switch (Stream.ReadSubBlockID()) {
686      default:  // Skip unknown content.
687        if (Stream.SkipBlock())
688          return Error("Malformed block record");
689        break;
690      case bitc::TYPE_BLOCK_ID:
691        if (ParseTypeTable(Stream))
692          return true;
693        break;
694      case bitc::TYPE_SYMTAB_BLOCK_ID:
695        if (ParseTypeSymbolTable(Stream))
696          return true;
697        break;
698      case bitc::VALUE_SYMTAB_BLOCK_ID:
699        if (ParseValueSymbolTable(Stream))
700          return true;
701        break;
702      case bitc::CONSTANTS_BLOCK_ID:
703        if (ParseConstants(Stream) || ResolveGlobalAndAliasInits())
704          return true;
705        break;
706      }
707      continue;
708    }
709
710    if (Code == bitc::DEFINE_ABBREV) {
711      Stream.ReadAbbrevRecord();
712      continue;
713    }
714
715    // Read a record.
716    switch (Stream.ReadRecord(Code, Record)) {
717    default: break;  // Default behavior, ignore unknown content.
718    case bitc::MODULE_CODE_VERSION:  // VERSION: [version#]
719      if (Record.size() < 1)
720        return Error("Malformed MODULE_CODE_VERSION");
721      // Only version #0 is supported so far.
722      if (Record[0] != 0)
723        return Error("Unknown bitstream version!");
724      break;
725    case bitc::MODULE_CODE_TRIPLE: {  // TRIPLE: [strlen, strchr x N]
726      std::string S;
727      if (ConvertToString(Record, 0, S))
728        return Error("Invalid MODULE_CODE_TRIPLE record");
729      TheModule->setTargetTriple(S);
730      break;
731    }
732    case bitc::MODULE_CODE_DATALAYOUT: {  // DATALAYOUT: [strlen, strchr x N]
733      std::string S;
734      if (ConvertToString(Record, 0, S))
735        return Error("Invalid MODULE_CODE_DATALAYOUT record");
736      TheModule->setDataLayout(S);
737      break;
738    }
739    case bitc::MODULE_CODE_ASM: {  // ASM: [strlen, strchr x N]
740      std::string S;
741      if (ConvertToString(Record, 0, S))
742        return Error("Invalid MODULE_CODE_ASM record");
743      TheModule->setModuleInlineAsm(S);
744      break;
745    }
746    case bitc::MODULE_CODE_DEPLIB: {  // DEPLIB: [strlen, strchr x N]
747      std::string S;
748      if (ConvertToString(Record, 0, S))
749        return Error("Invalid MODULE_CODE_DEPLIB record");
750      TheModule->addLibrary(S);
751      break;
752    }
753    case bitc::MODULE_CODE_SECTIONNAME: {  // SECTIONNAME: [strlen, strchr x N]
754      std::string S;
755      if (ConvertToString(Record, 0, S))
756        return Error("Invalid MODULE_CODE_SECTIONNAME record");
757      SectionTable.push_back(S);
758      break;
759    }
760    // GLOBALVAR: [type, isconst, initid,
761    //             linkage, alignment, section, visibility, threadlocal]
762    case bitc::MODULE_CODE_GLOBALVAR: {
763      if (Record.size() < 6)
764        return Error("Invalid MODULE_CODE_GLOBALVAR record");
765      const Type *Ty = getTypeByID(Record[0]);
766      if (!isa<PointerType>(Ty))
767        return Error("Global not a pointer type!");
768      Ty = cast<PointerType>(Ty)->getElementType();
769
770      bool isConstant = Record[1];
771      GlobalValue::LinkageTypes Linkage = GetDecodedLinkage(Record[3]);
772      unsigned Alignment = (1 << Record[4]) >> 1;
773      std::string Section;
774      if (Record[5]) {
775        if (Record[5]-1 >= SectionTable.size())
776          return Error("Invalid section ID");
777        Section = SectionTable[Record[5]-1];
778      }
779      GlobalValue::VisibilityTypes Visibility = GlobalValue::DefaultVisibility;
780      if (Record.size() >= 6) Visibility = GetDecodedVisibility(Record[6]);
781      bool isThreadLocal = false;
782      if (Record.size() >= 7) isThreadLocal = Record[7];
783
784      GlobalVariable *NewGV =
785        new GlobalVariable(Ty, isConstant, Linkage, 0, "", TheModule);
786      NewGV->setAlignment(Alignment);
787      if (!Section.empty())
788        NewGV->setSection(Section);
789      NewGV->setVisibility(Visibility);
790      NewGV->setThreadLocal(isThreadLocal);
791
792      ValueList.push_back(NewGV);
793
794      // Remember which value to use for the global initializer.
795      if (unsigned InitID = Record[2])
796        GlobalInits.push_back(std::make_pair(NewGV, InitID-1));
797      break;
798    }
799    // FUNCTION:  [type, callingconv, isproto, linkage, alignment, section,
800    //             visibility]
801    case bitc::MODULE_CODE_FUNCTION: {
802      if (Record.size() < 7)
803        return Error("Invalid MODULE_CODE_FUNCTION record");
804      const Type *Ty = getTypeByID(Record[0]);
805      if (!isa<PointerType>(Ty))
806        return Error("Function not a pointer type!");
807      const FunctionType *FTy =
808        dyn_cast<FunctionType>(cast<PointerType>(Ty)->getElementType());
809      if (!FTy)
810        return Error("Function not a pointer to function type!");
811
812      Function *Func = new Function(FTy, GlobalValue::ExternalLinkage,
813                                    "", TheModule);
814
815      Func->setCallingConv(Record[1]);
816      Func->setLinkage(GetDecodedLinkage(Record[3]));
817      Func->setAlignment((1 << Record[4]) >> 1);
818      if (Record[5]) {
819        if (Record[5]-1 >= SectionTable.size())
820          return Error("Invalid section ID");
821        Func->setSection(SectionTable[Record[5]-1]);
822      }
823      Func->setVisibility(GetDecodedVisibility(Record[6]));
824
825      ValueList.push_back(Func);
826      break;
827    }
828    // ALIAS: [alias type, aliasee val#, linkage]
829    case bitc::MODULE_CODE_ALIAS:
830      if (Record.size() < 3)
831        return Error("Invalid MODULE_ALIAS record");
832      const Type *Ty = getTypeByID(Record[0]);
833      if (!isa<PointerType>(Ty))
834        return Error("Function not a pointer type!");
835
836      GlobalAlias *NewGA = new GlobalAlias(Ty, GetDecodedLinkage(Record[2]),
837                                           "", 0, TheModule);
838      ValueList.push_back(NewGA);
839      AliasInits.push_back(std::make_pair(NewGA, Record[1]));
840      break;
841    }
842    Record.clear();
843  }
844
845  return Error("Premature end of bitstream");
846}
847
848
849bool BitcodeReader::ParseBitcode(unsigned char *Buf, unsigned Length,
850                                 const std::string &ModuleID) {
851  TheModule = 0;
852
853  if (Length & 3)
854    return Error("Bitcode stream should be a multiple of 4 bytes in length");
855
856  BitstreamReader Stream(Buf, Buf+Length);
857
858  // Sniff for the signature.
859  if (Stream.Read(8) != 'B' ||
860      Stream.Read(8) != 'C' ||
861      Stream.Read(4) != 0x0 ||
862      Stream.Read(4) != 0xC ||
863      Stream.Read(4) != 0xE ||
864      Stream.Read(4) != 0xD)
865    return Error("Invalid bitcode signature");
866
867  // We expect a number of well-defined blocks, though we don't necessarily
868  // need to understand them all.
869  while (!Stream.AtEndOfStream()) {
870    unsigned Code = Stream.ReadCode();
871
872    if (Code != bitc::ENTER_SUBBLOCK)
873      return Error("Invalid record at top-level");
874
875    unsigned BlockID = Stream.ReadSubBlockID();
876
877    // We only know the MODULE subblock ID.
878    if (BlockID == bitc::MODULE_BLOCK_ID) {
879      if (ParseModule(Stream, ModuleID))
880        return true;
881    } else if (Stream.SkipBlock()) {
882      return Error("Malformed block record");
883    }
884  }
885
886  return false;
887}
888