BitcodeReader.cpp revision f581c3b81ee793ce1dcce4b4755393e56148ea68 
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      return Stream.ReadBlockEnd();
165    }
166
167    if (Code == bitc::ENTER_SUBBLOCK) {
168      // No known subblocks, always skip them.
169      Stream.ReadSubBlockID();
170      if (Stream.SkipBlock())
171        return Error("Malformed block record");
172      continue;
173    }
174
175    if (Code == bitc::DEFINE_ABBREV) {
176      Stream.ReadAbbrevRecord();
177      continue;
178    }
179
180    // Read a record.
181    Record.clear();
182    const Type *ResultTy = 0;
183    switch (Stream.ReadRecord(Code, Record)) {
184    default:  // Default behavior: unknown type.
185      ResultTy = 0;
186      break;
187    case bitc::TYPE_CODE_NUMENTRY: // TYPE_CODE_NUMENTRY: [numentries]
188      // TYPE_CODE_NUMENTRY contains a count of the number of types in the
189      // type list.  This allows us to reserve space.
190      if (Record.size() < 1)
191        return Error("Invalid TYPE_CODE_NUMENTRY record");
192      TypeList.reserve(Record[0]);
193      continue;
194    case bitc::TYPE_CODE_META:      // TYPE_CODE_META: [metacode]...
195      // No metadata supported yet.
196      if (Record.size() < 1)
197        return Error("Invalid TYPE_CODE_META record");
198      continue;
199
200    case bitc::TYPE_CODE_VOID:      // VOID
201      ResultTy = Type::VoidTy;
202      break;
203    case bitc::TYPE_CODE_FLOAT:     // FLOAT
204      ResultTy = Type::FloatTy;
205      break;
206    case bitc::TYPE_CODE_DOUBLE:    // DOUBLE
207      ResultTy = Type::DoubleTy;
208      break;
209    case bitc::TYPE_CODE_LABEL:     // LABEL
210      ResultTy = Type::LabelTy;
211      break;
212    case bitc::TYPE_CODE_OPAQUE:    // OPAQUE
213      ResultTy = 0;
214      break;
215    case bitc::TYPE_CODE_INTEGER:   // INTEGER: [width]
216      if (Record.size() < 1)
217        return Error("Invalid Integer type record");
218
219      ResultTy = IntegerType::get(Record[0]);
220      break;
221    case bitc::TYPE_CODE_POINTER:   // POINTER: [pointee type]
222      if (Record.size() < 1)
223        return Error("Invalid POINTER type record");
224      ResultTy = PointerType::get(getTypeByID(Record[0], true));
225      break;
226    case bitc::TYPE_CODE_FUNCTION: {
227      // FUNCTION: [vararg, retty, #pararms, paramty N]
228      if (Record.size() < 3 || Record.size() < Record[2]+3)
229        return Error("Invalid FUNCTION type record");
230      std::vector<const Type*> ArgTys;
231      for (unsigned i = 0, e = Record[2]; i != e; ++i)
232        ArgTys.push_back(getTypeByID(Record[3+i], true));
233
234      // FIXME: PARAM TYS.
235      ResultTy = FunctionType::get(getTypeByID(Record[1], true), ArgTys,
236                                   Record[0]);
237      break;
238    }
239    case bitc::TYPE_CODE_STRUCT: {  // STRUCT: [ispacked, #elts, eltty x N]
240      if (Record.size() < 2 || Record.size() < Record[1]+2)
241        return Error("Invalid STRUCT type record");
242      std::vector<const Type*> EltTys;
243      for (unsigned i = 0, e = Record[1]; i != e; ++i)
244        EltTys.push_back(getTypeByID(Record[2+i], true));
245      ResultTy = StructType::get(EltTys, Record[0]);
246      break;
247    }
248    case bitc::TYPE_CODE_ARRAY:     // ARRAY: [numelts, eltty]
249      if (Record.size() < 2)
250        return Error("Invalid ARRAY type record");
251      ResultTy = ArrayType::get(getTypeByID(Record[1], true), Record[0]);
252      break;
253    case bitc::TYPE_CODE_VECTOR:    // VECTOR: [numelts, eltty]
254      if (Record.size() < 2)
255        return Error("Invalid VECTOR type record");
256      ResultTy = VectorType::get(getTypeByID(Record[1], true), Record[0]);
257      break;
258    }
259
260    if (NumRecords == TypeList.size()) {
261      // If this is a new type slot, just append it.
262      TypeList.push_back(ResultTy ? ResultTy : OpaqueType::get());
263      ++NumRecords;
264    } else if (ResultTy == 0) {
265      // Otherwise, this was forward referenced, so an opaque type was created,
266      // but the result type is actually just an opaque.  Leave the one we
267      // created previously.
268      ++NumRecords;
269    } else {
270      // Otherwise, this was forward referenced, so an opaque type was created.
271      // Resolve the opaque type to the real type now.
272      assert(NumRecords < TypeList.size() && "Typelist imbalance");
273      const OpaqueType *OldTy = cast<OpaqueType>(TypeList[NumRecords++].get());
274
275      // Don't directly push the new type on the Tab. Instead we want to replace
276      // the opaque type we previously inserted with the new concrete value. The
277      // refinement from the abstract (opaque) type to the new type causes all
278      // uses of the abstract type to use the concrete type (NewTy). This will
279      // also cause the opaque type to be deleted.
280      const_cast<OpaqueType*>(OldTy)->refineAbstractTypeTo(ResultTy);
281
282      // This should have replaced the old opaque type with the new type in the
283      // value table... or with a preexisting type that was already in the
284      // system.  Let's just make sure it did.
285      assert(TypeList[NumRecords-1].get() != OldTy &&
286             "refineAbstractType didn't work!");
287    }
288  }
289}
290
291
292bool BitcodeReader::ParseTypeSymbolTable(BitstreamReader &Stream) {
293  if (Stream.EnterSubBlock())
294    return Error("Malformed block record");
295
296  SmallVector<uint64_t, 64> Record;
297
298  // Read all the records for this type table.
299  std::string TypeName;
300  while (1) {
301    unsigned Code = Stream.ReadCode();
302    if (Code == bitc::END_BLOCK)
303      return Stream.ReadBlockEnd();
304
305    if (Code == bitc::ENTER_SUBBLOCK) {
306      // No known subblocks, always skip them.
307      Stream.ReadSubBlockID();
308      if (Stream.SkipBlock())
309        return Error("Malformed block record");
310      continue;
311    }
312
313    if (Code == bitc::DEFINE_ABBREV) {
314      Stream.ReadAbbrevRecord();
315      continue;
316    }
317
318    // Read a record.
319    Record.clear();
320    switch (Stream.ReadRecord(Code, Record)) {
321    default:  // Default behavior: unknown type.
322      break;
323    case bitc::TST_CODE_ENTRY:    // TST_ENTRY: [typeid, namelen, namechar x N]
324      if (ConvertToString(Record, 1, TypeName))
325        return Error("Invalid TST_ENTRY record");
326      unsigned TypeID = Record[0];
327      if (TypeID >= TypeList.size())
328        return Error("Invalid Type ID in TST_ENTRY record");
329
330      TheModule->addTypeName(TypeName, TypeList[TypeID].get());
331      TypeName.clear();
332      break;
333    }
334  }
335}
336
337bool BitcodeReader::ParseValueSymbolTable(BitstreamReader &Stream) {
338  if (Stream.EnterSubBlock())
339    return Error("Malformed block record");
340
341  SmallVector<uint64_t, 64> Record;
342
343  // Read all the records for this value table.
344  SmallString<128> ValueName;
345  while (1) {
346    unsigned Code = Stream.ReadCode();
347    if (Code == bitc::END_BLOCK)
348      return Stream.ReadBlockEnd();
349
350    if (Code == bitc::ENTER_SUBBLOCK) {
351      // No known subblocks, always skip them.
352      Stream.ReadSubBlockID();
353      if (Stream.SkipBlock())
354        return Error("Malformed block record");
355      continue;
356    }
357
358    if (Code == bitc::DEFINE_ABBREV) {
359      Stream.ReadAbbrevRecord();
360      continue;
361    }
362
363    // Read a record.
364    Record.clear();
365    switch (Stream.ReadRecord(Code, Record)) {
366    default:  // Default behavior: unknown type.
367      break;
368    case bitc::TST_CODE_ENTRY:    // VST_ENTRY: [valueid, namelen, namechar x N]
369      if (ConvertToString(Record, 1, ValueName))
370        return Error("Invalid TST_ENTRY record");
371      unsigned ValueID = Record[0];
372      if (ValueID >= ValueList.size())
373        return Error("Invalid Value ID in VST_ENTRY record");
374      Value *V = ValueList[ValueID];
375
376      V->setName(&ValueName[0], ValueName.size());
377      ValueName.clear();
378      break;
379    }
380  }
381}
382
383/// DecodeSignRotatedValue - Decode a signed value stored with the sign bit in
384/// the LSB for dense VBR encoding.
385static uint64_t DecodeSignRotatedValue(uint64_t V) {
386  if ((V & 1) == 0)
387    return V >> 1;
388  if (V != 1)
389    return -(V >> 1);
390  // There is no such thing as -0 with integers.  "-0" really means MININT.
391  return 1ULL << 63;
392}
393
394bool BitcodeReader::ParseConstants(BitstreamReader &Stream) {
395  if (Stream.EnterSubBlock())
396    return Error("Malformed block record");
397
398  SmallVector<uint64_t, 64> Record;
399
400  // Read all the records for this value table.
401  const Type *CurTy = Type::Int32Ty;
402  unsigned NextCstNo = ValueList.size();
403  while (1) {
404    unsigned Code = Stream.ReadCode();
405    if (Code == bitc::END_BLOCK) {
406      // If there are global var inits to process, do so now.
407      if (!GlobalInits.empty()) {
408        while (!GlobalInits.empty()) {
409          unsigned ValID = GlobalInits.back().second;
410          if (ValID >= ValueList.size())
411            return Error("Invalid value ID for global var init!");
412          if (Constant *C = dyn_cast<Constant>(ValueList[ValID]))
413            GlobalInits.back().first->setInitializer(C);
414          else
415            return Error("Global variable initializer is not a constant!");
416          GlobalInits.pop_back();
417        }
418      }
419
420      if (NextCstNo != ValueList.size())
421        return Error("Invalid constant reference!");
422
423      return Stream.ReadBlockEnd();
424    }
425
426    if (Code == bitc::ENTER_SUBBLOCK) {
427      // No known subblocks, always skip them.
428      Stream.ReadSubBlockID();
429      if (Stream.SkipBlock())
430        return Error("Malformed block record");
431      continue;
432    }
433
434    if (Code == bitc::DEFINE_ABBREV) {
435      Stream.ReadAbbrevRecord();
436      continue;
437    }
438
439    // Read a record.
440    Record.clear();
441    Value *V = 0;
442    switch (Stream.ReadRecord(Code, Record)) {
443    default:  // Default behavior: unknown constant
444    case bitc::CST_CODE_UNDEF:     // UNDEF
445      V = UndefValue::get(CurTy);
446      break;
447    case bitc::CST_CODE_SETTYPE:   // SETTYPE: [typeid]
448      if (Record.empty())
449        return Error("Malformed CST_SETTYPE record");
450      if (Record[0] >= TypeList.size())
451        return Error("Invalid Type ID in CST_SETTYPE record");
452      CurTy = TypeList[Record[0]];
453      continue;  // Skip the ValueList manipulation.
454    case bitc::CST_CODE_NULL:      // NULL
455      V = Constant::getNullValue(CurTy);
456      break;
457    case bitc::CST_CODE_INTEGER:   // INTEGER: [intval]
458      if (!isa<IntegerType>(CurTy) || Record.empty())
459        return Error("Invalid CST_INTEGER record");
460      V = ConstantInt::get(CurTy, DecodeSignRotatedValue(Record[0]));
461      break;
462    case bitc::CST_CODE_WIDE_INTEGER: {// WIDE_INTEGER: [n, n x intval]
463      if (!isa<IntegerType>(CurTy) || Record.empty() ||
464          Record.size() < Record[0]+1)
465        return Error("Invalid WIDE_INTEGER record");
466
467      unsigned NumWords = Record[0];
468      uint64_t *Data = new uint64_t[NumWords];
469      for (unsigned i = 0; i != NumWords; ++i)
470        Data[i] = DecodeSignRotatedValue(Record[i+1]);
471      V = ConstantInt::get(APInt(cast<IntegerType>(CurTy)->getBitWidth(),
472                                 NumWords, Data));
473      break;
474    }
475    case bitc::CST_CODE_FLOAT:     // FLOAT: [fpval]
476      if (Record.empty())
477        return Error("Invalid FLOAT record");
478      if (CurTy == Type::FloatTy)
479        V = ConstantFP::get(CurTy, BitsToFloat(Record[0]));
480      else if (CurTy == Type::DoubleTy)
481        V = ConstantFP::get(CurTy, BitsToDouble(Record[0]));
482      else
483        V = UndefValue::get(CurTy);
484      break;
485
486    case bitc::CST_CODE_AGGREGATE: {// AGGREGATE: [n, n x value number]
487      if (Record.empty() || Record.size() < Record[0]+1)
488        return Error("Invalid CST_AGGREGATE record");
489
490      unsigned Size = Record[0];
491      std::vector<Constant*> Elts;
492
493      if (const StructType *STy = dyn_cast<StructType>(CurTy)) {
494        for (unsigned i = 0; i != Size; ++i)
495          Elts.push_back(ValueList.getConstantFwdRef(Record[i+1],
496                                                     STy->getElementType(i)));
497        V = ConstantStruct::get(STy, Elts);
498      } else if (const ArrayType *ATy = dyn_cast<ArrayType>(CurTy)) {
499        const Type *EltTy = ATy->getElementType();
500        for (unsigned i = 0; i != Size; ++i)
501          Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], EltTy));
502        V = ConstantArray::get(ATy, Elts);
503      } else if (const VectorType *VTy = dyn_cast<VectorType>(CurTy)) {
504        const Type *EltTy = VTy->getElementType();
505        for (unsigned i = 0; i != Size; ++i)
506          Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], EltTy));
507        V = ConstantVector::get(Elts);
508      } else {
509        V = UndefValue::get(CurTy);
510      }
511      break;
512    }
513
514    case bitc::CST_CODE_CE_BINOP: {  // CE_BINOP: [opcode, opval, opval]
515      if (Record.size() < 3) return Error("Invalid CE_BINOP record");
516      int Opc = GetDecodedBinaryOpcode(Record[0], CurTy);
517      if (Opc < 0) return UndefValue::get(CurTy);  // Unknown binop.
518
519      Constant *LHS = ValueList.getConstantFwdRef(Record[1], CurTy);
520      Constant *RHS = ValueList.getConstantFwdRef(Record[2], CurTy);
521      V = ConstantExpr::get(Opc, LHS, RHS);
522      break;
523    }
524    case bitc::CST_CODE_CE_CAST: {  // CE_CAST: [opcode, opty, opval]
525      if (Record.size() < 3) return Error("Invalid CE_CAST record");
526      int Opc = GetDecodedCastOpcode(Record[0]);
527      if (Opc < 0) return UndefValue::get(CurTy);  // Unknown cast.
528
529      const Type *OpTy = getTypeByID(Record[1]);
530      Constant *Op = ValueList.getConstantFwdRef(Record[2], OpTy);
531      V = ConstantExpr::getCast(Opc, Op, CurTy);
532      break;
533    }
534    case bitc::CST_CODE_CE_GEP: {  // CE_GEP:        [n x operands]
535      if ((Record.size() & 1) == 0) return Error("Invalid CE_GEP record");
536      SmallVector<Constant*, 16> Elts;
537      for (unsigned i = 1, e = Record.size(); i != e; i += 2) {
538        const Type *ElTy = getTypeByID(Record[i]);
539        if (!ElTy) return Error("Invalid CE_GEP record");
540        Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], ElTy));
541      }
542      return ConstantExpr::getGetElementPtr(Elts[0], &Elts[1], Elts.size()-1);
543    }
544    case bitc::CST_CODE_CE_SELECT:  // CE_SELECT: [opval#, opval#, opval#]
545      if (Record.size() < 3) return Error("Invalid CE_SELECT record");
546      V = ConstantExpr::getSelect(ValueList.getConstantFwdRef(Record[0],
547                                                              Type::Int1Ty),
548                                  ValueList.getConstantFwdRef(Record[1],CurTy),
549                                  ValueList.getConstantFwdRef(Record[2],CurTy));
550      break;
551    case bitc::CST_CODE_CE_EXTRACTELT: { // CE_EXTRACTELT: [opty, opval, opval]
552      if (Record.size() < 3) return Error("Invalid CE_EXTRACTELT record");
553      const VectorType *OpTy =
554        dyn_cast_or_null<VectorType>(getTypeByID(Record[0]));
555      if (OpTy == 0) return Error("Invalid CE_EXTRACTELT record");
556      Constant *Op0 = ValueList.getConstantFwdRef(Record[1], OpTy);
557      Constant *Op1 = ValueList.getConstantFwdRef(Record[2],
558                                                  OpTy->getElementType());
559      V = ConstantExpr::getExtractElement(Op0, Op1);
560      break;
561    }
562    case bitc::CST_CODE_CE_INSERTELT: { // CE_INSERTELT: [opval, opval, opval]
563      const VectorType *OpTy = dyn_cast<VectorType>(CurTy);
564      if (Record.size() < 3 || OpTy == 0)
565        return Error("Invalid CE_INSERTELT record");
566      Constant *Op0 = ValueList.getConstantFwdRef(Record[0], OpTy);
567      Constant *Op1 = ValueList.getConstantFwdRef(Record[1],
568                                                  OpTy->getElementType());
569      Constant *Op2 = ValueList.getConstantFwdRef(Record[2], Type::Int32Ty);
570      V = ConstantExpr::getInsertElement(Op0, Op1, Op2);
571      break;
572    }
573    case bitc::CST_CODE_CE_SHUFFLEVEC: { // CE_SHUFFLEVEC: [opval, opval, opval]
574      const VectorType *OpTy = dyn_cast<VectorType>(CurTy);
575      if (Record.size() < 3 || OpTy == 0)
576        return Error("Invalid CE_INSERTELT record");
577      Constant *Op0 = ValueList.getConstantFwdRef(Record[0], OpTy);
578      Constant *Op1 = ValueList.getConstantFwdRef(Record[1], OpTy);
579      const Type *ShufTy=VectorType::get(Type::Int32Ty, OpTy->getNumElements());
580      Constant *Op2 = ValueList.getConstantFwdRef(Record[2], ShufTy);
581      V = ConstantExpr::getShuffleVector(Op0, Op1, Op2);
582      break;
583    }
584    case bitc::CST_CODE_CE_CMP: {     // CE_CMP: [opty, opval, opval, pred]
585      if (Record.size() < 4) return Error("Invalid CE_CMP record");
586      const Type *OpTy = getTypeByID(Record[0]);
587      if (OpTy == 0) return Error("Invalid CE_CMP record");
588      Constant *Op0 = ValueList.getConstantFwdRef(Record[1], OpTy);
589      Constant *Op1 = ValueList.getConstantFwdRef(Record[2], OpTy);
590
591      if (OpTy->isFloatingPoint())
592        V = ConstantExpr::getFCmp(Record[3], Op0, Op1);
593      else
594        V = ConstantExpr::getICmp(Record[3], Op0, Op1);
595      break;
596    }
597    }
598
599    if (NextCstNo == ValueList.size())
600      ValueList.push_back(V);
601    else if (ValueList[NextCstNo] == 0)
602      ValueList.initVal(NextCstNo, V);
603    else {
604      // If there was a forward reference to this constant,
605      Value *OldV = ValueList[NextCstNo];
606      ValueList.setOperand(NextCstNo, V);
607      OldV->replaceAllUsesWith(V);
608      delete OldV;
609    }
610
611    ++NextCstNo;
612  }
613}
614
615bool BitcodeReader::ParseModule(BitstreamReader &Stream,
616                                const std::string &ModuleID) {
617  // Reject multiple MODULE_BLOCK's in a single bitstream.
618  if (TheModule)
619    return Error("Multiple MODULE_BLOCKs in same stream");
620
621  if (Stream.EnterSubBlock())
622    return Error("Malformed block record");
623
624  // Otherwise, create the module.
625  TheModule = new Module(ModuleID);
626
627  SmallVector<uint64_t, 64> Record;
628  std::vector<std::string> SectionTable;
629
630  // Read all the records for this module.
631  while (!Stream.AtEndOfStream()) {
632    unsigned Code = Stream.ReadCode();
633    if (Code == bitc::END_BLOCK) {
634      if (!GlobalInits.empty())
635        return Error("Malformed global initializer set");
636      return Stream.ReadBlockEnd();
637    }
638
639    if (Code == bitc::ENTER_SUBBLOCK) {
640      switch (Stream.ReadSubBlockID()) {
641      default:  // Skip unknown content.
642        if (Stream.SkipBlock())
643          return Error("Malformed block record");
644        break;
645      case bitc::TYPE_BLOCK_ID:
646        if (ParseTypeTable(Stream))
647          return true;
648        break;
649      case bitc::TYPE_SYMTAB_BLOCK_ID:
650        if (ParseTypeSymbolTable(Stream))
651          return true;
652        break;
653      case bitc::VALUE_SYMTAB_BLOCK_ID:
654        if (ParseValueSymbolTable(Stream))
655          return true;
656        break;
657      case bitc::CONSTANTS_BLOCK_ID:
658        if (ParseConstants(Stream))
659          return true;
660        break;
661      }
662      continue;
663    }
664
665    if (Code == bitc::DEFINE_ABBREV) {
666      Stream.ReadAbbrevRecord();
667      continue;
668    }
669
670    // Read a record.
671    switch (Stream.ReadRecord(Code, Record)) {
672    default: break;  // Default behavior, ignore unknown content.
673    case bitc::MODULE_CODE_VERSION:  // VERSION: [version#]
674      if (Record.size() < 1)
675        return Error("Malformed MODULE_CODE_VERSION");
676      // Only version #0 is supported so far.
677      if (Record[0] != 0)
678        return Error("Unknown bitstream version!");
679      break;
680    case bitc::MODULE_CODE_TRIPLE: {  // TRIPLE: [strlen, strchr x N]
681      std::string S;
682      if (ConvertToString(Record, 0, S))
683        return Error("Invalid MODULE_CODE_TRIPLE record");
684      TheModule->setTargetTriple(S);
685      break;
686    }
687    case bitc::MODULE_CODE_DATALAYOUT: {  // DATALAYOUT: [strlen, strchr x N]
688      std::string S;
689      if (ConvertToString(Record, 0, S))
690        return Error("Invalid MODULE_CODE_DATALAYOUT record");
691      TheModule->setDataLayout(S);
692      break;
693    }
694    case bitc::MODULE_CODE_ASM: {  // ASM: [strlen, strchr x N]
695      std::string S;
696      if (ConvertToString(Record, 0, S))
697        return Error("Invalid MODULE_CODE_ASM record");
698      TheModule->setModuleInlineAsm(S);
699      break;
700    }
701    case bitc::MODULE_CODE_DEPLIB: {  // DEPLIB: [strlen, strchr x N]
702      std::string S;
703      if (ConvertToString(Record, 0, S))
704        return Error("Invalid MODULE_CODE_DEPLIB record");
705      TheModule->addLibrary(S);
706      break;
707    }
708    case bitc::MODULE_CODE_SECTIONNAME: {  // SECTIONNAME: [strlen, strchr x N]
709      std::string S;
710      if (ConvertToString(Record, 0, S))
711        return Error("Invalid MODULE_CODE_SECTIONNAME record");
712      SectionTable.push_back(S);
713      break;
714    }
715    // GLOBALVAR: [type, isconst, initid,
716    //             linkage, alignment, section, visibility, threadlocal]
717    case bitc::MODULE_CODE_GLOBALVAR: {
718      if (Record.size() < 6)
719        return Error("Invalid MODULE_CODE_GLOBALVAR record");
720      const Type *Ty = getTypeByID(Record[0]);
721      if (!isa<PointerType>(Ty))
722        return Error("Global not a pointer type!");
723      Ty = cast<PointerType>(Ty)->getElementType();
724
725      bool isConstant = Record[1];
726      GlobalValue::LinkageTypes Linkage = GetDecodedLinkage(Record[3]);
727      unsigned Alignment = (1 << Record[4]) >> 1;
728      std::string Section;
729      if (Record[5]) {
730        if (Record[5]-1 >= SectionTable.size())
731          return Error("Invalid section ID");
732        Section = SectionTable[Record[5]-1];
733      }
734      GlobalValue::VisibilityTypes Visibility = GlobalValue::DefaultVisibility;
735      if (Record.size() >= 6) Visibility = GetDecodedVisibility(Record[6]);
736      bool isThreadLocal = false;
737      if (Record.size() >= 7) isThreadLocal = Record[7];
738
739      GlobalVariable *NewGV =
740        new GlobalVariable(Ty, isConstant, Linkage, 0, "", TheModule);
741      NewGV->setAlignment(Alignment);
742      if (!Section.empty())
743        NewGV->setSection(Section);
744      NewGV->setVisibility(Visibility);
745      NewGV->setThreadLocal(isThreadLocal);
746
747      ValueList.push_back(NewGV);
748
749      // Remember which value to use for the global initializer.
750      if (unsigned InitID = Record[2])
751        GlobalInits.push_back(std::make_pair(NewGV, InitID-1));
752      break;
753    }
754    // FUNCTION:  [type, callingconv, isproto, linkage, alignment, section,
755    //             visibility]
756    case bitc::MODULE_CODE_FUNCTION: {
757      if (Record.size() < 7)
758        return Error("Invalid MODULE_CODE_FUNCTION record");
759      const Type *Ty = getTypeByID(Record[0]);
760      if (!isa<PointerType>(Ty))
761        return Error("Function not a pointer type!");
762      const FunctionType *FTy =
763        dyn_cast<FunctionType>(cast<PointerType>(Ty)->getElementType());
764      if (!FTy)
765        return Error("Function not a pointer to function type!");
766
767      Function *Func = new Function(FTy, GlobalValue::ExternalLinkage,
768                                    "", TheModule);
769
770      Func->setCallingConv(Record[1]);
771      Func->setLinkage(GetDecodedLinkage(Record[3]));
772      Func->setAlignment((1 << Record[4]) >> 1);
773      if (Record[5]) {
774        if (Record[5]-1 >= SectionTable.size())
775          return Error("Invalid section ID");
776        Func->setSection(SectionTable[Record[5]-1]);
777      }
778      Func->setVisibility(GetDecodedVisibility(Record[6]));
779
780      ValueList.push_back(Func);
781      // TODO: remember initializer/global pair for later substitution.
782      break;
783    }
784    }
785    Record.clear();
786  }
787
788  return Error("Premature end of bitstream");
789}
790
791
792bool BitcodeReader::ParseBitcode(unsigned char *Buf, unsigned Length,
793                                 const std::string &ModuleID) {
794  TheModule = 0;
795
796  if (Length & 3)
797    return Error("Bitcode stream should be a multiple of 4 bytes in length");
798
799  BitstreamReader Stream(Buf, Buf+Length);
800
801  // Sniff for the signature.
802  if (Stream.Read(8) != 'B' ||
803      Stream.Read(8) != 'C' ||
804      Stream.Read(4) != 0x0 ||
805      Stream.Read(4) != 0xC ||
806      Stream.Read(4) != 0xE ||
807      Stream.Read(4) != 0xD)
808    return Error("Invalid bitcode signature");
809
810  // We expect a number of well-defined blocks, though we don't necessarily
811  // need to understand them all.
812  while (!Stream.AtEndOfStream()) {
813    unsigned Code = Stream.ReadCode();
814
815    if (Code != bitc::ENTER_SUBBLOCK)
816      return Error("Invalid record at top-level");
817
818    unsigned BlockID = Stream.ReadSubBlockID();
819
820    // We only know the MODULE subblock ID.
821    if (BlockID == bitc::MODULE_BLOCK_ID) {
822      if (ParseModule(Stream, ModuleID))
823        return true;
824    } else if (Stream.SkipBlock()) {
825      return Error("Malformed block record");
826    }
827  }
828
829  return false;
830}
831