MachineModuleInfo.cpp

//===-- llvm/CodeGen/MachineModuleInfo.cpp ----------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/MachineModuleInfo.h"

#include "llvm/Constants.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineLocation.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/DerivedTypes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Intrinsics.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/Streams.h"
using namespace llvm;
using namespace llvm::dwarf;

// Handle the Pass registration stuff necessary to use TargetData's.
static RegisterPass<MachineModuleInfo>
X("machinemoduleinfo", "Module Information");
char MachineModuleInfo::ID = 0;

//===----------------------------------------------------------------------===//

/// getGlobalVariablesUsing - Return all of the GlobalVariables which have the
/// specified value in their initializer somewhere.
static void
getGlobalVariablesUsing(Value *V, std::vector<GlobalVariable*> &Result) {
  // Scan though value users.
  for (Value::use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I) {
    if (GlobalVariable *GV = dyn_cast<GlobalVariable>(*I)) {
      // If the user is a GlobalVariable then add to result.
      Result.push_back(GV);
    } else if (Constant *C = dyn_cast<Constant>(*I)) {
      // If the user is a constant variable then scan its users
      getGlobalVariablesUsing(C, Result);
    }
  }
}

/// getGlobalVariablesUsing - Return all of the GlobalVariables that use the
/// named GlobalVariable.
static void
getGlobalVariablesUsing(Module &M, const std::string &RootName,
                        std::vector<GlobalVariable*> &Result) {
  std::vector<const Type*> FieldTypes;
  FieldTypes.push_back(Type::Int32Ty);
  FieldTypes.push_back(Type::Int32Ty);

  // Get the GlobalVariable root.
  GlobalVariable *UseRoot = M.getGlobalVariable(RootName,
                                                StructType::get(FieldTypes));

  // If present and linkonce then scan for users.
  if (UseRoot && UseRoot->hasLinkOnceLinkage())
    getGlobalVariablesUsing(UseRoot, Result);
}
  
/// isStringValue - Return true if the given value can be coerced to a string.
///
static bool isStringValue(Value *V) {
  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
    if (GV->hasInitializer() && isa<ConstantArray>(GV->getInitializer())) {
      ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
      return Init->isString();
    }
  } else if (Constant *C = dyn_cast<Constant>(V)) {
    if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
      return isStringValue(GV);
    else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
      if (CE->getOpcode() == Instruction::GetElementPtr) {
        if (CE->getNumOperands() == 3 &&
            cast<Constant>(CE->getOperand(1))->isNullValue() &&
            isa<ConstantInt>(CE->getOperand(2))) {
          return isStringValue(CE->getOperand(0));
        }
      }
    }
  }
  return false;
}

/// getGlobalVariable - Return either a direct or cast Global value.
///
static GlobalVariable *getGlobalVariable(Value *V) {
  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
    return GV;
  } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
    if (CE->getOpcode() == Instruction::BitCast) {
      return dyn_cast<GlobalVariable>(CE->getOperand(0));
    } else if (CE->getOpcode() == Instruction::GetElementPtr) {
      for (unsigned int i=1; i<CE->getNumOperands(); i++) {
        if (!CE->getOperand(i)->isNullValue())
          return NULL;
      }
      return dyn_cast<GlobalVariable>(CE->getOperand(0));
    }
  }
  return NULL;
}

/// isGlobalVariable - Return true if the given value can be coerced to a
/// GlobalVariable.
static bool isGlobalVariable(Value *V) {
  if (isa<GlobalVariable>(V) || isa<ConstantPointerNull>(V)) {
    return true;
  } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
    if (CE->getOpcode() == Instruction::BitCast) {
      return isa<GlobalVariable>(CE->getOperand(0));
    } else if (CE->getOpcode() == Instruction::GetElementPtr) {
      for (unsigned int i=1; i<CE->getNumOperands(); i++) {
        if (!CE->getOperand(i)->isNullValue())
          return false;
      }
      return isa<GlobalVariable>(CE->getOperand(0));
    }
  }
  return false;
}

/// getUIntOperand - Return ith operand if it is an unsigned integer.
///
static ConstantInt *getUIntOperand(GlobalVariable *GV, unsigned i) {
  // Make sure the GlobalVariable has an initializer.
  if (!GV->hasInitializer()) return NULL;
  
  // Get the initializer constant.
  ConstantStruct *CI = dyn_cast<ConstantStruct>(GV->getInitializer());
  if (!CI) return NULL;
  
  // Check if there is at least i + 1 operands.
  unsigned N = CI->getNumOperands();
  if (i >= N) return NULL;

  // Check constant.
  return dyn_cast<ConstantInt>(CI->getOperand(i));
}

//===----------------------------------------------------------------------===//

static unsigned CountFields(DebugInfoDesc *DD) {
  unsigned Count = 0;

  switch (DD->getTag()) {
  case DW_TAG_anchor:           // AnchorDesc
    // Tag
    // AnchorTag
    Count = 2;
    break;
  case DW_TAG_compile_unit:     // CompileUnitDesc
    // [DW_TAG_anchor]
    // if (Version == 0) DebugVersion
    // Language
    // FileName
    // Directory
    // Producer
    Count = 6;
  
    // Handle cases out of sync with compiler.
    if (DD->getVersion() == 0)
      ++Count;

    break;
  case DW_TAG_variable:         // GlobalVariableDesc
    // [DW_TAG_anchor]
    // Context
    // Name
    // FullName
    // LinkageName
    // File
    // Line
    // TyDesc
    // IsStatic
    // IsDefinition
    // Global
    Count = 12;
    break;
  case DW_TAG_subprogram:       // SubprogramDesc
    // [DW_TAG_anchor]
    // Context
    // Name
    // FullName
    // LinkageName
    // File
    // Line
    // TyDesc
    // IsStatic
    // IsDefinition
    Count = 11;
    break;
  case DW_TAG_lexical_block:    // BlockDesc
    // Tag
    // Context
    Count = 2;
    break;
  case DW_TAG_base_type:        // BasicTypeDesc
    // Tag
    // Context
    // Name
    // File
    // Line
    // Size
    // Align
    // Offset
    // if (Version > LLVMDebugVersion4) Flags
    // Encoding
    Count = 9;

    if (DD->getVersion() > LLVMDebugVersion4)
      ++Count;

    break;
  case DW_TAG_typedef:
  case DW_TAG_pointer_type:        
  case DW_TAG_reference_type:
  case DW_TAG_const_type:
  case DW_TAG_volatile_type:        
  case DW_TAG_restrict_type:
  case DW_TAG_member:
  case DW_TAG_inheritance:      // DerivedTypeDesc
    // Tag
    // Context
    // Name
    // File
    // Line
    // Size
    // Align
    // Offset
    // if (Version > LLVMDebugVersion4) Flags
    // FromType
    Count = 9;

    if (DD->getVersion() > LLVMDebugVersion4)
      ++Count;

    break;
  case DW_TAG_array_type:
  case DW_TAG_structure_type:
  case DW_TAG_union_type:
  case DW_TAG_enumeration_type:
  case DW_TAG_vector_type:
  case DW_TAG_subroutine_type:  // CompositeTypeDesc
    // Tag
    // Context
    // Name
    // File
    // Line
    // Size
    // Align
    // Offset
    // if (Version > LLVMDebugVersion4) Flags
    // FromType
    // Elements
    Count = 10;

    if (DD->getVersion() > LLVMDebugVersion4)
      ++Count;

    break;
  case DW_TAG_subrange_type:    // SubrangeDesc
    // Tag
    // Lo
    // Hi
    Count = 3;
    break;
  case DW_TAG_enumerator:       // EnumeratorDesc
    // Tag
    // Name
    // Value
    Count = 3;
    break;
  case DW_TAG_return_variable:
  case DW_TAG_arg_variable:
  case DW_TAG_auto_variable:    // VariableDesc
    // Tag
    // Context
    // Name
    // File
    // Line
    // TyDesc
    Count = 6;
    break;
  default:
    break;
  }

  return Count;
}

//===----------------------------------------------------------------------===//

/// ApplyToFields - Target the visitor to each field of the debug information
/// descriptor.
void DIVisitor::ApplyToFields(DebugInfoDesc *DD) {
  DD->ApplyToFields(this);
}

namespace {

//===----------------------------------------------------------------------===//
/// DIDeserializeVisitor - This DIVisitor deserializes all the fields in the
/// supplied DebugInfoDesc.
class DIDeserializeVisitor : public DIVisitor {
private:
  DIDeserializer &DR;                   // Active deserializer.
  unsigned I;                           // Current operand index.
  ConstantStruct *CI;                   // GlobalVariable constant initializer.

public:
  DIDeserializeVisitor(DIDeserializer &D, GlobalVariable *GV)
    : DIVisitor(), DR(D), I(0), CI(cast<ConstantStruct>(GV->getInitializer()))
  {}
  
  /// Apply - Set the value of each of the fields.
  ///
  virtual void Apply(int &Field) {
    Constant *C = CI->getOperand(I++);
    Field = cast<ConstantInt>(C)->getSExtValue();
  }
  virtual void Apply(unsigned &Field) {
    Constant *C = CI->getOperand(I++);
    Field = cast<ConstantInt>(C)->getZExtValue();
  }
  virtual void Apply(int64_t &Field) {
    Constant *C = CI->getOperand(I++);
    Field = cast<ConstantInt>(C)->getSExtValue();
  }
  virtual void Apply(uint64_t &Field) {
    Constant *C = CI->getOperand(I++);
    Field = cast<ConstantInt>(C)->getZExtValue();
  }
  virtual void Apply(bool &Field) {
    Constant *C = CI->getOperand(I++);
    Field = cast<ConstantInt>(C)->getZExtValue();
  }
  virtual void Apply(std::string &Field) {
    Constant *C = CI->getOperand(I++);
    // Fills in the string if it succeeds
    if (!GetConstantStringInfo(C, Field))
      Field.clear();
  }
  virtual void Apply(DebugInfoDesc *&Field) {
    Constant *C = CI->getOperand(I++);
    Field = DR.Deserialize(C);
  }
  virtual void Apply(GlobalVariable *&Field) {
    Constant *C = CI->getOperand(I++);
    Field = getGlobalVariable(C);
  }
  virtual void Apply(std::vector<DebugInfoDesc *> &Field) {
    Field.resize(0);
    Constant *C = CI->getOperand(I++);
    GlobalVariable *GV = getGlobalVariable(C);
    if (GV->hasInitializer()) {
      if (ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer())) {
        for (unsigned i = 0, N = CA->getNumOperands(); i < N; ++i) {
          GlobalVariable *GVE = getGlobalVariable(CA->getOperand(i));
          DebugInfoDesc *DE = DR.Deserialize(GVE);
          Field.push_back(DE);
        }
      } else if (GV->getInitializer()->isNullValue()) {
        if (const ArrayType *T =
            dyn_cast<ArrayType>(GV->getType()->getElementType())) {
          Field.resize(T->getNumElements());
        }
      }
    }
  }
};

//===----------------------------------------------------------------------===//
/// DISerializeVisitor - This DIVisitor serializes all the fields in
/// the supplied DebugInfoDesc.
class DISerializeVisitor : public DIVisitor {
private:
  DISerializer &SR;                     // Active serializer.
  std::vector<Constant*> &Elements;     // Element accumulator.
  
public:
  DISerializeVisitor(DISerializer &S, std::vector<Constant*> &E)
  : DIVisitor()
  , SR(S)
  , Elements(E)
  {}
  
  /// Apply - Set the value of each of the fields.
  ///
  virtual void Apply(int &Field) {
    Elements.push_back(ConstantInt::get(Type::Int32Ty, int32_t(Field)));
  }
  virtual void Apply(unsigned &Field) {
    Elements.push_back(ConstantInt::get(Type::Int32Ty, uint32_t(Field)));
  }
  virtual void Apply(int64_t &Field) {
    Elements.push_back(ConstantInt::get(Type::Int64Ty, int64_t(Field)));
  }
  virtual void Apply(uint64_t &Field) {
    Elements.push_back(ConstantInt::get(Type::Int64Ty, uint64_t(Field)));
  }
  virtual void Apply(bool &Field) {
    Elements.push_back(ConstantInt::get(Type::Int1Ty, Field));
  }
  virtual void Apply(std::string &Field) {
    Elements.push_back(SR.getString(Field));
  }
  virtual void Apply(DebugInfoDesc *&Field) {
    GlobalVariable *GV = NULL;
    
    // If non-NULL then convert to global.
    if (Field) GV = SR.Serialize(Field);
    
    // FIXME - At some point should use specific type.
    const PointerType *EmptyTy = SR.getEmptyStructPtrType();
    
    if (GV) {
      // Set to pointer to global.
      Elements.push_back(ConstantExpr::getBitCast(GV, EmptyTy));
    } else {
      // Use NULL.
      Elements.push_back(ConstantPointerNull::get(EmptyTy));
    }
  }
  virtual void Apply(GlobalVariable *&Field) {
    const PointerType *EmptyTy = SR.getEmptyStructPtrType();
    if (Field) {
      Elements.push_back(ConstantExpr::getBitCast(Field, EmptyTy));
    } else {
      Elements.push_back(ConstantPointerNull::get(EmptyTy));
    }
  }
  virtual void Apply(std::vector<DebugInfoDesc *> &Field) {
    const PointerType *EmptyTy = SR.getEmptyStructPtrType();
    unsigned N = Field.size();
    ArrayType *AT = ArrayType::get(EmptyTy, N);
    std::vector<Constant *> ArrayElements;

    for (unsigned i = 0, N = Field.size(); i < N; ++i) {
      if (DebugInfoDesc *Element = Field[i]) {
        GlobalVariable *GVE = SR.Serialize(Element);
        Constant *CE = ConstantExpr::getBitCast(GVE, EmptyTy);
        ArrayElements.push_back(cast<Constant>(CE));
      } else {
        ArrayElements.push_back(ConstantPointerNull::get(EmptyTy));
      }
    }
    
    Constant *CA = ConstantArray::get(AT, ArrayElements);
    GlobalVariable *CAGV = new GlobalVariable(AT, true,
                                              GlobalValue::InternalLinkage,
                                              CA, "llvm.dbg.array",
                                              SR.getModule());
    CAGV->setSection("llvm.metadata");
    Constant *CAE = ConstantExpr::getBitCast(CAGV, EmptyTy);
    Elements.push_back(CAE);
  }
};

//===----------------------------------------------------------------------===//
/// DIGetTypesVisitor - This DIVisitor gathers all the field types in
/// the supplied DebugInfoDesc.
class DIGetTypesVisitor : public DIVisitor {
private:
  DISerializer &SR;                     // Active serializer.
  std::vector<const Type*> &Fields;     // Type accumulator.
  
public:
  DIGetTypesVisitor(DISerializer &S, std::vector<const Type*> &F)
  : DIVisitor()
  , SR(S)
  , Fields(F)
  {}
  
  /// Apply - Set the value of each of the fields.
  ///
  virtual void Apply(int &Field) {
    Fields.push_back(Type::Int32Ty);
  }
  virtual void Apply(unsigned &Field) {
    Fields.push_back(Type::Int32Ty);
  }
  virtual void Apply(int64_t &Field) {
    Fields.push_back(Type::Int64Ty);
  }
  virtual void Apply(uint64_t &Field) {
    Fields.push_back(Type::Int64Ty);
  }
  virtual void Apply(bool &Field) {
    Fields.push_back(Type::Int1Ty);
  }
  virtual void Apply(std::string &Field) {
    Fields.push_back(SR.getStrPtrType());
  }
  virtual void Apply(DebugInfoDesc *&Field) {
    // FIXME - At some point should use specific type.
    const PointerType *EmptyTy = SR.getEmptyStructPtrType();
    Fields.push_back(EmptyTy);
  }
  virtual void Apply(GlobalVariable *&Field) {
    const PointerType *EmptyTy = SR.getEmptyStructPtrType();
    Fields.push_back(EmptyTy);
  }
  virtual void Apply(std::vector<DebugInfoDesc *> &Field) {
    const PointerType *EmptyTy = SR.getEmptyStructPtrType();
    Fields.push_back(EmptyTy);
  }
};

//===----------------------------------------------------------------------===//
/// DIVerifyVisitor - This DIVisitor verifies all the field types against
/// a constant initializer.
class DIVerifyVisitor : public DIVisitor {
private:
  DIVerifier &VR;                       // Active verifier.
  bool IsValid;                         // Validity status.
  unsigned I;                           // Current operand index.
  ConstantStruct *CI;                   // GlobalVariable constant initializer.
  
public:
  DIVerifyVisitor(DIVerifier &V, GlobalVariable *GV)
  : DIVisitor()
  , VR(V)
  , IsValid(true)
  , I(0)
  , CI(cast<ConstantStruct>(GV->getInitializer()))
  {
  }
  
  // Accessors.
  bool isValid() const { return IsValid; }
  
  /// Apply - Set the value of each of the fields.
  ///
  virtual void Apply(int &Field) {
    Constant *C = CI->getOperand(I++);
    IsValid = IsValid && isa<ConstantInt>(C);
  }
  virtual void Apply(unsigned &Field) {
    Constant *C = CI->getOperand(I++);
    IsValid = IsValid && isa<ConstantInt>(C);
  }
  virtual void Apply(int64_t &Field) {
    Constant *C = CI->getOperand(I++);
    IsValid = IsValid && isa<ConstantInt>(C);
  }
  virtual void Apply(uint64_t &Field) {
    Constant *C = CI->getOperand(I++);
    IsValid = IsValid && isa<ConstantInt>(C);
  }
  virtual void Apply(bool &Field) {
    Constant *C = CI->getOperand(I++);
    IsValid = IsValid && isa<ConstantInt>(C) && C->getType() == Type::Int1Ty;
  }
  virtual void Apply(std::string &Field) {
    Constant *C = CI->getOperand(I++);
    IsValid = IsValid &&
              (!C || isStringValue(C) || C->isNullValue());
  }
  virtual void Apply(DebugInfoDesc *&Field) {
    // FIXME - Prepare the correct descriptor.
    Constant *C = CI->getOperand(I++);
    IsValid = IsValid && isGlobalVariable(C);
  }
  virtual void Apply(GlobalVariable *&Field) {
    Constant *C = CI->getOperand(I++);
    IsValid = IsValid && isGlobalVariable(C);
  }
  virtual void Apply(std::vector<DebugInfoDesc *> &Field) {
    Constant *C = CI->getOperand(I++);
    IsValid = IsValid && isGlobalVariable(C);
    if (!IsValid) return;

    GlobalVariable *GV = getGlobalVariable(C);
    IsValid = IsValid && GV && GV->hasInitializer();
    if (!IsValid) return;
    
    ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
    IsValid = IsValid && CA;
    if (!IsValid) return;

    for (unsigned i = 0, N = CA->getNumOperands(); IsValid && i < N; ++i) {
      IsValid = IsValid && isGlobalVariable(CA->getOperand(i));
      if (!IsValid) return;
    
      GlobalVariable *GVE = getGlobalVariable(CA->getOperand(i));
      VR.Verify(GVE);
    }
  }
};

}

//===----------------------------------------------------------------------===//

/// TagFromGlobal - Returns the tag number from a debug info descriptor
/// GlobalVariable.   Return DIIValid if operand is not an unsigned int. 
unsigned DebugInfoDesc::TagFromGlobal(GlobalVariable *GV) {
  ConstantInt *C = getUIntOperand(GV, 0);
  return C ? ((unsigned)C->getZExtValue() & ~LLVMDebugVersionMask) :
             (unsigned)DW_TAG_invalid;
}

/// VersionFromGlobal - Returns the version number from a debug info
/// descriptor GlobalVariable.  Return DIIValid if operand is not an unsigned
/// int.
unsigned  DebugInfoDesc::VersionFromGlobal(GlobalVariable *GV) {
  ConstantInt *C = getUIntOperand(GV, 0);
  return C ? ((unsigned)C->getZExtValue() & LLVMDebugVersionMask) :
             (unsigned)DW_TAG_invalid;
}

/// DescFactory - Create an instance of debug info descriptor based on Tag.
/// Return NULL if not a recognized Tag.
DebugInfoDesc *DebugInfoDesc::DescFactory(unsigned Tag) {
  switch (Tag) {
  case DW_TAG_anchor:           return new AnchorDesc();
  case DW_TAG_compile_unit:     return new CompileUnitDesc();
  case DW_TAG_variable:         return new GlobalVariableDesc();
  case DW_TAG_subprogram:       return new SubprogramDesc();
  case DW_TAG_lexical_block:    return new BlockDesc();
  case DW_TAG_base_type:        return new BasicTypeDesc();
  case DW_TAG_typedef:
  case DW_TAG_pointer_type:        
  case DW_TAG_reference_type:
  case DW_TAG_const_type:
  case DW_TAG_volatile_type:        
  case DW_TAG_restrict_type:
  case DW_TAG_member:
  case DW_TAG_inheritance:      return new DerivedTypeDesc(Tag);
  case DW_TAG_array_type:
  case DW_TAG_structure_type:
  case DW_TAG_union_type:
  case DW_TAG_enumeration_type:
  case DW_TAG_vector_type:
  case DW_TAG_subroutine_type:  return new CompositeTypeDesc(Tag);
  case DW_TAG_subrange_type:    return new SubrangeDesc();
  case DW_TAG_enumerator:       return new EnumeratorDesc();
  case DW_TAG_return_variable:
  case DW_TAG_arg_variable:
  case DW_TAG_auto_variable:    return new VariableDesc(Tag);
  default: break;
  }
  return NULL;
}

/// getLinkage - get linkage appropriate for this type of descriptor.
///
GlobalValue::LinkageTypes DebugInfoDesc::getLinkage() const {
  return GlobalValue::InternalLinkage;
}

/// ApplyToFields - Target the vistor to the fields of the descriptor.
///
void DebugInfoDesc::ApplyToFields(DIVisitor *Visitor) {
  Visitor->Apply(Tag);
}

//===----------------------------------------------------------------------===//

AnchorDesc::AnchorDesc()
: DebugInfoDesc(DW_TAG_anchor)
, AnchorTag(0)
{}
AnchorDesc::AnchorDesc(AnchoredDesc *D)
: DebugInfoDesc(DW_TAG_anchor)
, AnchorTag(D->getTag())
{}

// Implement isa/cast/dyncast.
bool AnchorDesc::classof(const DebugInfoDesc *D) {
  return D->getTag() == DW_TAG_anchor;
}
  
/// getLinkage - get linkage appropriate for this type of descriptor.
///
GlobalValue::LinkageTypes AnchorDesc::getLinkage() const {
  return GlobalValue::LinkOnceLinkage;
}

/// ApplyToFields - Target the visitor to the fields of the TransUnitDesc.
///
void AnchorDesc::ApplyToFields(DIVisitor *Visitor) {
  DebugInfoDesc::ApplyToFields(Visitor);
  
  Visitor->Apply(AnchorTag);
}

/// getDescString - Return a string used to compose global names and labels. A
/// A global variable name needs to be defined for each debug descriptor that is
/// anchored. NOTE: that each global variable named here also needs to be added
/// to the list of names left external in the internalizer.
///   ExternalNames.insert("llvm.dbg.compile_units");
///   ExternalNames.insert("llvm.dbg.global_variables");
///   ExternalNames.insert("llvm.dbg.subprograms");
const char *AnchorDesc::getDescString() const {
  switch (AnchorTag) {
  case DW_TAG_compile_unit: return CompileUnitDesc::AnchorString;
  case DW_TAG_variable:     return GlobalVariableDesc::AnchorString;
  case DW_TAG_subprogram:   return SubprogramDesc::AnchorString;
  default: break;
  }

  assert(0 && "Tag does not have a case for anchor string");
  return "";
}

/// getTypeString - Return a string used to label this descriptors type.
///
const char *AnchorDesc::getTypeString() const {
  return "llvm.dbg.anchor.type";
}

#ifndef NDEBUG
void AnchorDesc::dump() {
  cerr << getDescString() << " "
       << "Version(" << getVersion() << "), "
       << "Tag(" << getTag() << "), "
       << "AnchorTag(" << AnchorTag << ")\n";
}
#endif

//===----------------------------------------------------------------------===//

AnchoredDesc::AnchoredDesc(unsigned T)
: DebugInfoDesc(T)
, Anchor(NULL)
{}

/// ApplyToFields - Target the visitor to the fields of the AnchoredDesc.
///
void AnchoredDesc::ApplyToFields(DIVisitor *Visitor) {
  DebugInfoDesc::ApplyToFields(Visitor);

  Visitor->Apply(Anchor);
}

//===----------------------------------------------------------------------===//

CompileUnitDesc::CompileUnitDesc()
: AnchoredDesc(DW_TAG_compile_unit)
, Language(0)
, FileName("")
, Directory("")
, Producer("")
{}

// Implement isa/cast/dyncast.
bool CompileUnitDesc::classof(const DebugInfoDesc *D) {
  return D->getTag() == DW_TAG_compile_unit;
}

/// ApplyToFields - Target the visitor to the fields of the CompileUnitDesc.
///
void CompileUnitDesc::ApplyToFields(DIVisitor *Visitor) {
  AnchoredDesc::ApplyToFields(Visitor);
  
  // Handle cases out of sync with compiler.
  if (getVersion() == 0) {
    unsigned DebugVersion;
    Visitor->Apply(DebugVersion);
  }

  Visitor->Apply(Language);
  Visitor->Apply(FileName);
  Visitor->Apply(Directory);
  Visitor->Apply(Producer);
}

/// getDescString - Return a string used to compose global names and labels.
///
const char *CompileUnitDesc::getDescString() const {
  return "llvm.dbg.compile_unit";
}

/// getTypeString - Return a string used to label this descriptors type.
///
const char *CompileUnitDesc::getTypeString() const {
  return "llvm.dbg.compile_unit.type";
}

/// getAnchorString - Return a string used to label this descriptor's anchor.
///
const char *const CompileUnitDesc::AnchorString = "llvm.dbg.compile_units";
const char *CompileUnitDesc::getAnchorString() const {
  return AnchorString;
}

#ifndef NDEBUG
void CompileUnitDesc::dump() {
  cerr << getDescString() << " "
       << "Version(" << getVersion() << "), "
       << "Tag(" << getTag() << "), "
       << "Anchor(" << getAnchor() << "), "
       << "Language(" << Language << "), "
       << "FileName(\"" << FileName << "\"), "
       << "Directory(\"" << Directory << "\"), "
       << "Producer(\"" << Producer << "\")\n";
}
#endif

//===----------------------------------------------------------------------===//

TypeDesc::TypeDesc(unsigned T)
: DebugInfoDesc(T)
, Context(NULL)
, Name("")
, File(NULL)
, Line(0)
, Size(0)
, Align(0)
, Offset(0)
, Flags(0)
{}

/// ApplyToFields - Target the visitor to the fields of the TypeDesc.
///
void TypeDesc::ApplyToFields(DIVisitor *Visitor) {
  DebugInfoDesc::ApplyToFields(Visitor);
  
  Visitor->Apply(Context);
  Visitor->Apply(Name);
  Visitor->Apply(File);
  Visitor->Apply(Line);
  Visitor->Apply(Size);
  Visitor->Apply(Align);
  Visitor->Apply(Offset);
  if (getVersion() > LLVMDebugVersion4) Visitor->Apply(Flags);
}

/// getDescString - Return a string used to compose global names and labels.
///
const char *TypeDesc::getDescString() const {
  return "llvm.dbg.type";
}

/// getTypeString - Return a string used to label this descriptor's type.
///
const char *TypeDesc::getTypeString() const {
  return "llvm.dbg.type.type";
}

#ifndef NDEBUG
void TypeDesc::dump() {
  cerr << getDescString() << " "
       << "Version(" << getVersion() << "), "
       << "Tag(" << getTag() << "), "
       << "Context(" << Context << "), "
       << "Name(\"" << Name << "\"), "
       << "File(" << File << "), "
       << "Line(" << Line << "), "
       << "Size(" << Size << "), "
       << "Align(" << Align << "), "
       << "Offset(" << Offset << "), "
       << "Flags(" << Flags << ")\n";
}
#endif

//===----------------------------------------------------------------------===//

BasicTypeDesc::BasicTypeDesc()
: TypeDesc(DW_TAG_base_type)
, Encoding(0)
{}

// Implement isa/cast/dyncast.
bool BasicTypeDesc::classof(const DebugInfoDesc *D) {
  return D->getTag() == DW_TAG_base_type;
}

/// ApplyToFields - Target the visitor to the fields of the BasicTypeDesc.
///
void BasicTypeDesc::ApplyToFields(DIVisitor *Visitor) {
  TypeDesc::ApplyToFields(Visitor);
  
  Visitor->Apply(Encoding);
}

/// getDescString - Return a string used to compose global names and labels.
///
const char *BasicTypeDesc::getDescString() const {
  return "llvm.dbg.basictype";
}

/// getTypeString - Return a string used to label this descriptor's type.
///
const char *BasicTypeDesc::getTypeString() const {
  return "llvm.dbg.basictype.type";
}

#ifndef NDEBUG
void BasicTypeDesc::dump() {
  cerr << getDescString() << " "
       << "Version(" << getVersion() << "), "
       << "Tag(" << getTag() << "), "
       << "Context(" << getContext() << "), "
       << "Name(\"" << getName() << "\"), "
       << "Size(" << getSize() << "), "
       << "Encoding(" << Encoding << ")\n";
}
#endif

//===----------------------------------------------------------------------===//

DerivedTypeDesc::DerivedTypeDesc(unsigned T)
: TypeDesc(T)
, FromType(NULL)
{}

// Implement isa/cast/dyncast.
bool DerivedTypeDesc::classof(const DebugInfoDesc *D) {
  unsigned T =  D->getTag();
  switch (T) {
  case DW_TAG_typedef:
  case DW_TAG_pointer_type:
  case DW_TAG_reference_type:
  case DW_TAG_const_type:
  case DW_TAG_volatile_type:
  case DW_TAG_restrict_type:
  case DW_TAG_member:
  case DW_TAG_inheritance:
    return true;
  default: break;
  }
  return false;
}

/// ApplyToFields - Target the visitor to the fields of the DerivedTypeDesc.
///
void DerivedTypeDesc::ApplyToFields(DIVisitor *Visitor) {
  TypeDesc::ApplyToFields(Visitor);
  
  Visitor->Apply(FromType);
}

/// getDescString - Return a string used to compose global names and labels.
///
const char *DerivedTypeDesc::getDescString() const {
  return "llvm.dbg.derivedtype";
}

/// getTypeString - Return a string used to label this descriptor's type.
///
const char *DerivedTypeDesc::getTypeString() const {
  return "llvm.dbg.derivedtype.type";
}

#ifndef NDEBUG
void DerivedTypeDesc::dump() {
  cerr << getDescString() << " "
       << "Version(" << getVersion() << "), "
       << "Tag(" << getTag() << "), "
       << "Context(" << getContext() << "), "
       << "Name(\"" << getName() << "\"), "
       << "Size(" << getSize() << "), "
       << "File(" << getFile() << "), "
       << "Line(" << getLine() << "), "
       << "FromType(" << FromType << ")\n";
}
#endif

//===----------------------------------------------------------------------===//

CompositeTypeDesc::CompositeTypeDesc(unsigned T)
: DerivedTypeDesc(T)
, Elements()
{}
  
// Implement isa/cast/dyncast.
bool CompositeTypeDesc::classof(const DebugInfoDesc *D) {
  unsigned T =  D->getTag();
  switch (T) {
  case DW_TAG_array_type:
  case DW_TAG_structure_type:
  case DW_TAG_union_type:
  case DW_TAG_enumeration_type:
  case DW_TAG_vector_type:
  case DW_TAG_subroutine_type:
    return true;
  default: break;
  }
  return false;
}

/// ApplyToFields - Target the visitor to the fields of the CompositeTypeDesc.
///
void CompositeTypeDesc::ApplyToFields(DIVisitor *Visitor) {
  DerivedTypeDesc::ApplyToFields(Visitor);  

  Visitor->Apply(Elements);