I missed this new file in previous commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129407 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -0,0 +1,973 @@
+//===-- llvm/CodeGen/DwarfCompileUnit.cpp - Dwarf Compile Unit ------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing dwarf compile unit.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "dwarfdebug"
+
+#include "DwarfCompileUnit.h"
+#include "DwarfDebug.h"
+#include "llvm/Constants.h"
+#include "llvm/Analysis/DIBuilder.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetFrameLowering.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/ADT/APFloat.h"
+#include "llvm/Support/ErrorHandling.h"
+
+using namespace llvm;
+
+/// CompileUnit - Compile unit constructor.
+CompileUnit::CompileUnit(unsigned I, DIE *D, AsmPrinter *A, DwarfDebug *DW)
+  : ID(I), CUDie(D), Asm(A), DD(DW), IndexTyDie(0) {
+  DIEIntegerOne = new (DIEValueAllocator) DIEInteger(1);
+}
+
+/// ~CompileUnit - Destructor for compile unit.
+CompileUnit::~CompileUnit() {
+  for (unsigned j = 0, M = DIEBlocks.size(); j < M; ++j)
+    DIEBlocks[j]->~DIEBlock();
+}
+
+/// createDIEEntry - Creates a new DIEEntry to be a proxy for a debug
+/// information entry.
+DIEEntry *CompileUnit::createDIEEntry(DIE *Entry) {
+  DIEEntry *Value = new (DIEValueAllocator) DIEEntry(Entry);
+  return Value;
+}
+
+/// addUInt - Add an unsigned integer attribute data and value.
+///
+void CompileUnit::addUInt(DIE *Die, unsigned Attribute,
+                          unsigned Form, uint64_t Integer) {
+  if (!Form) Form = DIEInteger::BestForm(false, Integer);
+  DIEValue *Value = Integer == 1 ?
+    DIEIntegerOne : new (DIEValueAllocator) DIEInteger(Integer);
+  Die->addValue(Attribute, Form, Value);
+}
+
+/// addSInt - Add an signed integer attribute data and value.
+///
+void CompileUnit::addSInt(DIE *Die, unsigned Attribute,
+                          unsigned Form, int64_t Integer) {
+  if (!Form) Form = DIEInteger::BestForm(true, Integer);
+  DIEValue *Value = new (DIEValueAllocator) DIEInteger(Integer);
+  Die->addValue(Attribute, Form, Value);
+}
+
+/// addString - Add a string attribute data and value. DIEString only
+/// keeps string reference.
+void CompileUnit::addString(DIE *Die, unsigned Attribute, unsigned Form,
+                            StringRef String) {
+  DIEValue *Value = new (DIEValueAllocator) DIEString(String);
+  Die->addValue(Attribute, Form, Value);
+}
+
+/// addLabel - Add a Dwarf label attribute data and value.
+///
+void CompileUnit::addLabel(DIE *Die, unsigned Attribute, unsigned Form,
+                           const MCSymbol *Label) {
+  DIEValue *Value = new (DIEValueAllocator) DIELabel(Label);
+  Die->addValue(Attribute, Form, Value);
+}
+
+/// addDelta - Add a label delta attribute data and value.
+///
+void CompileUnit::addDelta(DIE *Die, unsigned Attribute, unsigned Form,
+                           const MCSymbol *Hi, const MCSymbol *Lo) {
+  DIEValue *Value = new (DIEValueAllocator) DIEDelta(Hi, Lo);
+  Die->addValue(Attribute, Form, Value);
+}
+
+/// addDIEEntry - Add a DIE attribute data and value.
+///
+void CompileUnit::addDIEEntry(DIE *Die, unsigned Attribute, unsigned Form,
+                              DIE *Entry) {
+  Die->addValue(Attribute, Form, createDIEEntry(Entry));
+}
+
+
+/// addBlock - Add block data.
+///
+void CompileUnit::addBlock(DIE *Die, unsigned Attribute, unsigned Form,
+                           DIEBlock *Block) {
+  Block->ComputeSize(Asm);
+  DIEBlocks.push_back(Block); // Memoize so we can call the destructor later on.
+  Die->addValue(Attribute, Block->BestForm(), Block);
+}
+
+/// addSourceLine - Add location information to specified debug information
+/// entry.
+void CompileUnit::addSourceLine(DIE *Die, DIVariable V) {
+  // Verify variable.
+  if (!V.Verify())
+    return;
+  
+  unsigned Line = V.getLineNumber();
+  if (Line == 0)
+    return;
+  unsigned FileID = DD->GetOrCreateSourceID(V.getContext().getFilename(),
+                                            V.getContext().getDirectory());
+  assert(FileID && "Invalid file id");
+  addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
+  addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
+}
+
+/// addSourceLine - Add location information to specified debug information
+/// entry.
+void CompileUnit::addSourceLine(DIE *Die, DIGlobalVariable G) {
+  // Verify global variable.
+  if (!G.Verify())
+    return;
+
+  unsigned Line = G.getLineNumber();
+  if (Line == 0)
+    return;
+  unsigned FileID = DD->GetOrCreateSourceID(G.getContext().getFilename(),
+                                            G.getContext().getDirectory());
+  assert(FileID && "Invalid file id");
+  addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
+  addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
+}
+
+/// addSourceLine - Add location information to specified debug information
+/// entry.
+void CompileUnit::addSourceLine(DIE *Die, DISubprogram SP) {
+  // Verify subprogram.
+  if (!SP.Verify())
+    return;
+  // If the line number is 0, don't add it.
+  if (SP.getLineNumber() == 0)
+    return;
+
+  unsigned Line = SP.getLineNumber();
+  if (!SP.getContext().Verify())
+    return;
+  unsigned FileID = DD->GetOrCreateSourceID(SP.getFilename(), SP.getDirectory());
+  assert(FileID && "Invalid file id");
+  addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
+  addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
+}
+
+/// addSourceLine - Add location information to specified debug information
+/// entry.
+void CompileUnit::addSourceLine(DIE *Die, DIType Ty) {
+  // Verify type.
+  if (!Ty.Verify())
+    return;
+
+  unsigned Line = Ty.getLineNumber();
+  if (Line == 0 || !Ty.getContext().Verify())
+    return;
+  unsigned FileID = DD->GetOrCreateSourceID(Ty.getFilename(), Ty.getDirectory());
+  assert(FileID && "Invalid file id");
+  addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
+  addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
+}
+
+/// addSourceLine - Add location information to specified debug information
+/// entry.
+void CompileUnit::addSourceLine(DIE *Die, DINameSpace NS) {
+  // Verify namespace.
+  if (!NS.Verify())
+    return;
+
+  unsigned Line = NS.getLineNumber();
+  if (Line == 0)
+    return;
+  StringRef FN = NS.getFilename();
+
+  unsigned FileID = DD->GetOrCreateSourceID(FN, NS.getDirectory());
+  assert(FileID && "Invalid file id");
+  addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
+  addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
+}
+
+/// addVariableAddress - Add DW_AT_location attribute for a DbgVariable based
+/// on provided frame index.
+void CompileUnit::addVariableAddress(DbgVariable *&DV, DIE *Die, int64_t FI) {
+  MachineLocation Location;
+  unsigned FrameReg;
+  const TargetFrameLowering *TFI = Asm->TM.getFrameLowering();
+  int Offset = TFI->getFrameIndexReference(*Asm->MF, FI, FrameReg);
+  Location.set(FrameReg, Offset);
+
+  if (DV->variableHasComplexAddress())
+    addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
+  else if (DV->isBlockByrefVariable())
+    addBlockByrefAddress(DV, Die, dwarf::DW_AT_location, Location);
+  else
+    addAddress(Die, dwarf::DW_AT_location, Location);
+}
+
+/// addComplexAddress - Start with the address based on the location provided,
+/// and generate the DWARF information necessary to find the actual variable
+/// given the extra address information encoded in the DIVariable, starting from
+/// the starting location.  Add the DWARF information to the die.
+///
+void CompileUnit::addComplexAddress(DbgVariable *&DV, DIE *Die,
+                                    unsigned Attribute,
+                                    const MachineLocation &Location) {
+  DIType Ty = DV->getType();
+
+  // Decode the original location, and use that as the start of the byref
+  // variable's location.
+  const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
+  unsigned Reg = RI->getDwarfRegNum(Location.getReg(), false);
+  DIEBlock *Block = new (DIEValueAllocator) DIEBlock();
+
+  if (Location.isReg()) {
+    if (Reg < 32) {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_reg0 + Reg);
+    } else {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_regx);
+      addUInt(Block, 0, dwarf::DW_FORM_udata, Reg);
+    }
+  } else {
+    if (Reg < 32)
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_breg0 + Reg);
+    else {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_bregx);
+      addUInt(Block, 0, dwarf::DW_FORM_udata, Reg);
+    }
+
+    addUInt(Block, 0, dwarf::DW_FORM_sdata, Location.getOffset());
+  }
+
+  for (unsigned i = 0, N = DV->getNumAddrElements(); i < N; ++i) {
+    uint64_t Element = DV->getAddrElement(i);
+
+    if (Element == DIBuilder::OpPlus) {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_plus_uconst);
+      addUInt(Block, 0, dwarf::DW_FORM_udata, DV->getAddrElement(++i));
+    } else if (Element == DIBuilder::OpDeref) {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
+    } else llvm_unreachable("unknown DIBuilder Opcode");
+  }
+
+  // Now attach the location information to the DIE.
+  addBlock(Die, Attribute, 0, Block);
+}
+
+/* Byref variables, in Blocks, are declared by the programmer as "SomeType
+   VarName;", but the compiler creates a __Block_byref_x_VarName struct, and
+   gives the variable VarName either the struct, or a pointer to the struct, as
+   its type.  This is necessary for various behind-the-scenes things the
+   compiler needs to do with by-reference variables in Blocks.
+
+   However, as far as the original *programmer* is concerned, the variable
+   should still have type 'SomeType', as originally declared.
+
+   The function getBlockByrefType dives into the __Block_byref_x_VarName
+   struct to find the original type of the variable, which is then assigned to
+   the variable's Debug Information Entry as its real type.  So far, so good.
+   However now the debugger will expect the variable VarName to have the type
+   SomeType.  So we need the location attribute for the variable to be an
+   expression that explains to the debugger how to navigate through the
+   pointers and struct to find the actual variable of type SomeType.
+
+   The following function does just that.  We start by getting
+   the "normal" location for the variable. This will be the location
+   of either the struct __Block_byref_x_VarName or the pointer to the
+   struct __Block_byref_x_VarName.
+
+   The struct will look something like:
+
+   struct __Block_byref_x_VarName {
+     ... <various fields>
+     struct __Block_byref_x_VarName *forwarding;
+     ... <various other fields>
+     SomeType VarName;
+     ... <maybe more fields>
+   };
+
+   If we are given the struct directly (as our starting point) we
+   need to tell the debugger to:
+
+   1).  Add the offset of the forwarding field.
+
+   2).  Follow that pointer to get the real __Block_byref_x_VarName
+   struct to use (the real one may have been copied onto the heap).
+
+   3).  Add the offset for the field VarName, to find the actual variable.
+
+   If we started with a pointer to the struct, then we need to
+   dereference that pointer first, before the other steps.
+   Translating this into DWARF ops, we will need to append the following
+   to the current location description for the variable:
+
+   DW_OP_deref                    -- optional, if we start with a pointer
+   DW_OP_plus_uconst <forward_fld_offset>
+   DW_OP_deref
+   DW_OP_plus_uconst <varName_fld_offset>
+
+   That is what this function does.  */
+
+/// addBlockByrefAddress - Start with the address based on the location
+/// provided, and generate the DWARF information necessary to find the
+/// actual Block variable (navigating the Block struct) based on the
+/// starting location.  Add the DWARF information to the die.  For
+/// more information, read large comment just above here.
+///
+void CompileUnit::addBlockByrefAddress(DbgVariable *&DV, DIE *Die,
+                                       unsigned Attribute,
+                                       const MachineLocation &Location) {
+  DIType Ty = DV->getType();
+  DIType TmpTy = Ty;
+  unsigned Tag = Ty.getTag();
+  bool isPointer = false;
+
+  StringRef varName = DV->getName();
+
+  if (Tag == dwarf::DW_TAG_pointer_type) {
+    DIDerivedType DTy = DIDerivedType(Ty);
+    TmpTy = DTy.getTypeDerivedFrom();
+    isPointer = true;
+  }
+
+  DICompositeType blockStruct = DICompositeType(TmpTy);
+
+  // Find the __forwarding field and the variable field in the __Block_byref
+  // struct.
+  DIArray Fields = blockStruct.getTypeArray();
+  DIDescriptor varField = DIDescriptor();
+  DIDescriptor forwardingField = DIDescriptor();
+
+  for (unsigned i = 0, N = Fields.getNumElements(); i < N; ++i) {
+    DIDescriptor Element = Fields.getElement(i);
+    DIDerivedType DT = DIDerivedType(Element);
+    StringRef fieldName = DT.getName();
+    if (fieldName == "__forwarding")
+      forwardingField = Element;
+    else if (fieldName == varName)
+      varField = Element;
+  }
+
+  // Get the offsets for the forwarding field and the variable field.
+  unsigned forwardingFieldOffset =
+    DIDerivedType(forwardingField).getOffsetInBits() >> 3;
+  unsigned varFieldOffset =
+    DIDerivedType(varField).getOffsetInBits() >> 3;
+
+  // Decode the original location, and use that as the start of the byref
+  // variable's location.
+  const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
+  unsigned Reg = RI->getDwarfRegNum(Location.getReg(), false);
+  DIEBlock *Block = new (DIEValueAllocator) DIEBlock();
+
+  if (Location.isReg()) {
+    if (Reg < 32)
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_reg0 + Reg);
+    else {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_regx);
+      addUInt(Block, 0, dwarf::DW_FORM_udata, Reg);
+    }
+  } else {
+    if (Reg < 32)
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_breg0 + Reg);
+    else {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_bregx);
+      addUInt(Block, 0, dwarf::DW_FORM_udata, Reg);
+    }
+
+    addUInt(Block, 0, dwarf::DW_FORM_sdata, Location.getOffset());
+  }
+
+  // If we started with a pointer to the __Block_byref... struct, then
+  // the first thing we need to do is dereference the pointer (DW_OP_deref).
+  if (isPointer)
+    addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
+
+  // Next add the offset for the '__forwarding' field:
+  // DW_OP_plus_uconst ForwardingFieldOffset.  Note there's no point in
+  // adding the offset if it's 0.
+  if (forwardingFieldOffset > 0) {
+    addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_plus_uconst);
+    addUInt(Block, 0, dwarf::DW_FORM_udata, forwardingFieldOffset);
+  }
+
+  // Now dereference the __forwarding field to get to the real __Block_byref
+  // struct:  DW_OP_deref.
+  addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
+
+  // Now that we've got the real __Block_byref... struct, add the offset
+  // for the variable's field to get to the location of the actual variable:
+  // DW_OP_plus_uconst varFieldOffset.  Again, don't add if it's 0.
+  if (varFieldOffset > 0) {
+    addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_plus_uconst);
+    addUInt(Block, 0, dwarf::DW_FORM_udata, varFieldOffset);
+  }
+
+  // Now attach the location information to the DIE.
+  addBlock(Die, Attribute, 0, Block);
+}
+
+/// addAddress - Add an address attribute to a die based on the location
+/// provided.
+void CompileUnit::addAddress(DIE *Die, unsigned Attribute,
+                             const MachineLocation &Location) {
+  const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
+  unsigned Reg = RI->getDwarfRegNum(Location.getReg(), false);
+  DIEBlock *Block = new (DIEValueAllocator) DIEBlock();
+
+  if (RI->getFrameRegister(*Asm->MF) == Location.getReg()
+      && Location.getOffset()) {
+    // If variable offset is based in frame register then use fbreg.
+    addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_fbreg);
+    addSInt(Block, 0, dwarf::DW_FORM_sdata, Location.getOffset());
+    addBlock(Die, Attribute, 0, Block);
+    return;
+  }
+
+  if (Location.isReg()) {
+    if (Reg < 32) {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_reg0 + Reg);
+    } else {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_regx);
+      addUInt(Block, 0, dwarf::DW_FORM_udata, Reg);
+    }
+  } else {
+    if (Reg < 32) {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_breg0 + Reg);
+    } else {
+      addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_bregx);
+      addUInt(Block, 0, dwarf::DW_FORM_udata, Reg);
+    }
+
+    addUInt(Block, 0, dwarf::DW_FORM_sdata, Location.getOffset());
+  }
+
+  addBlock(Die, Attribute, 0, Block);
+}
+
+/// addRegisterAddress - Add register location entry in variable DIE.
+bool CompileUnit::addRegisterAddress(DIE *Die, const MachineOperand &MO) {
+  assert (MO.isReg() && "Invalid machine operand!");
+  if (!MO.getReg())
+    return false;
+  MachineLocation Location;
+  Location.set(MO.getReg());
+  addAddress(Die, dwarf::DW_AT_location, Location);
+  return true;
+}
+
+/// addConstantValue - Add constant value entry in variable DIE.
+bool CompileUnit::addConstantValue(DIE *Die, const MachineOperand &MO) {
+  assert (MO.isImm() && "Invalid machine operand!");
+  DIEBlock *Block = new (DIEValueAllocator) DIEBlock();
+  unsigned Imm = MO.getImm();
+  addUInt(Block, 0, dwarf::DW_FORM_udata, Imm);
+  addBlock(Die, dwarf::DW_AT_const_value, 0, Block);
+  return true;
+}
+
+/// addConstantFPValue - Add constant value entry in variable DIE.
+bool CompileUnit::addConstantFPValue(DIE *Die, const MachineOperand &MO) {
+  assert (MO.isFPImm() && "Invalid machine operand!");
+  DIEBlock *Block = new (DIEValueAllocator) DIEBlock();
+  APFloat FPImm = MO.getFPImm()->getValueAPF();
+
+  // Get the raw data form of the floating point.
+  const APInt FltVal = FPImm.bitcastToAPInt();
+  const char *FltPtr = (const char*)FltVal.getRawData();
+
+  int NumBytes = FltVal.getBitWidth() / 8; // 8 bits per byte.
+  bool LittleEndian = Asm->getTargetData().isLittleEndian();
+  int Incr = (LittleEndian ? 1 : -1);
+  int Start = (LittleEndian ? 0 : NumBytes - 1);
+  int Stop = (LittleEndian ? NumBytes : -1);
+
+  // Output the constant to DWARF one byte at a time.
+  for (; Start != Stop; Start += Incr)
+    addUInt(Block, 0, dwarf::DW_FORM_data1,
+            (unsigned char)0xFF & FltPtr[Start]);
+
+  addBlock(Die, dwarf::DW_AT_const_value, 0, Block);
+  return true;
+}
+
+/// addConstantValue - Add constant value entry in variable DIE.
+bool CompileUnit::addConstantValue(DIE *Die, ConstantInt *CI,
+                                   bool Unsigned) {
+  if (CI->getBitWidth() <= 64) {
+    if (Unsigned)
+      addUInt(Die, dwarf::DW_AT_const_value, dwarf::DW_FORM_udata,
+              CI->getZExtValue());
+    else
+      addSInt(Die, dwarf::DW_AT_const_value, dwarf::DW_FORM_sdata,
+              CI->getSExtValue());
+    return true;
+  }
+
+  DIEBlock *Block = new (DIEValueAllocator) DIEBlock();
+
+  // Get the raw data form of the large APInt.
+  const APInt Val = CI->getValue();
+  const char *Ptr = (const char*)Val.getRawData();
+
+  int NumBytes = Val.getBitWidth() / 8; // 8 bits per byte.
+  bool LittleEndian = Asm->getTargetData().isLittleEndian();
+  int Incr = (LittleEndian ? 1 : -1);
+  int Start = (LittleEndian ? 0 : NumBytes - 1);
+  int Stop = (LittleEndian ? NumBytes : -1);
+
+  // Output the constant to DWARF one byte at a time.
+  for (; Start != Stop; Start += Incr)
+    addUInt(Block, 0, dwarf::DW_FORM_data1,
+            (unsigned char)0xFF & Ptr[Start]);
+
+  addBlock(Die, dwarf::DW_AT_const_value, 0, Block);
+  return true;
+}
+
+/// addTemplateParams - Add template parameters in buffer.
+void CompileUnit::addTemplateParams(DIE &Buffer, DIArray TParams) {
+  // Add template parameters.
+  for (unsigned i = 0, e = TParams.getNumElements(); i != e; ++i) {
+    DIDescriptor Element = TParams.getElement(i);
+    if (Element.isTemplateTypeParameter())
+      Buffer.addChild(getOrCreateTemplateTypeParameterDIE(
+                        DITemplateTypeParameter(Element)));
+    else if (Element.isTemplateValueParameter())
+      Buffer.addChild(getOrCreateTemplateValueParameterDIE(
+                        DITemplateValueParameter(Element)));
+  }
+
+}
+/// addToContextOwner - Add Die into the list of its context owner's children.
+void CompileUnit::addToContextOwner(DIE *Die, DIDescriptor Context) {
+  if (Context.isType()) {
+    DIE *ContextDIE = getOrCreateTypeDIE(DIType(Context));
+    ContextDIE->addChild(Die);
+  } else if (Context.isNameSpace()) {
+    DIE *ContextDIE = getOrCreateNameSpace(DINameSpace(Context));
+    ContextDIE->addChild(Die);
+  } else if (Context.isSubprogram()) {
+    DIE *ContextDIE = DD->createSubprogramDIE(DISubprogram(Context));
+    ContextDIE->addChild(Die);
+  } else if (DIE *ContextDIE = getDIE(Context))
+    ContextDIE->addChild(Die);
+  else
+    addDie(Die);
+}
+
+/// getOrCreateTypeDIE - Find existing DIE or create new DIE for the
+/// given DIType.
+DIE *CompileUnit::getOrCreateTypeDIE(DIType Ty) {
+  DIE *TyDIE = getDIE(Ty);
+  if (TyDIE)
+    return TyDIE;
+
+  // Create new type.
+  TyDIE = new DIE(dwarf::DW_TAG_base_type);
+  insertDIE(Ty, TyDIE);
+  if (Ty.isBasicType())
+    constructTypeDIE(*TyDIE, DIBasicType(Ty));
+  else if (Ty.isCompositeType())
+    constructTypeDIE(*TyDIE, DICompositeType(Ty));
+  else {
+    assert(Ty.isDerivedType() && "Unknown kind of DIType");
+    constructTypeDIE(*TyDIE, DIDerivedType(Ty));
+  }
+
+  addToContextOwner(TyDIE, Ty.getContext());
+  return TyDIE;
+}
+
+/// addType - Add a new type attribute to the specified entity.
+void CompileUnit::addType(DIE *Entity, DIType Ty) {
+  if (!Ty.Verify())
+    return;
+
+  // Check for pre-existence.
+  DIEEntry *Entry = getDIEEntry(Ty);
+  // If it exists then use the existing value.
+  if (Entry) {
+    Entity->addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, Entry);
+    return;
+  }
+
+  // Construct type.
+  DIE *Buffer = getOrCreateTypeDIE(Ty);
+
+  // Set up proxy.
+  Entry = createDIEEntry(Buffer);
+  insertDIEEntry(Ty, Entry);
+
+  Entity->addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, Entry);
+}
+
+/// constructTypeDIE - Construct basic type die from DIBasicType.
+void CompileUnit::constructTypeDIE(DIE &Buffer, DIBasicType BTy) {
+  // Get core information.
+  StringRef Name = BTy.getName();
+  Buffer.setTag(dwarf::DW_TAG_base_type);
+  addUInt(&Buffer, dwarf::DW_AT_encoding,  dwarf::DW_FORM_data1,
+          BTy.getEncoding());
+
+  // Add name if not anonymous or intermediate type.
+  if (!Name.empty())
+    addString(&Buffer, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
+  uint64_t Size = BTy.getSizeInBits() >> 3;
+  addUInt(&Buffer, dwarf::DW_AT_byte_size, 0, Size);
+}
+
+/// constructTypeDIE - Construct derived type die from DIDerivedType.
+void CompileUnit::constructTypeDIE(DIE &Buffer, DIDerivedType DTy) {
+  // Get core information.
+  StringRef Name = DTy.getName();
+  uint64_t Size = DTy.getSizeInBits() >> 3;
+  unsigned Tag = DTy.getTag();
+
+  // FIXME - Workaround for templates.
+  if (Tag == dwarf::DW_TAG_inheritance) Tag = dwarf::DW_TAG_reference_type;
+
+  Buffer.setTag(Tag);
+
+  // Map to main type, void will not have a type.
+  DIType FromTy = DTy.getTypeDerivedFrom();
+  addType(&Buffer, FromTy);
+
+  // Add name if not anonymous or intermediate type.
+  if (!Name.empty())
+    addString(&Buffer, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
+
+  // Add size if non-zero (derived types might be zero-sized.)
+  if (Size)
+    addUInt(&Buffer, dwarf::DW_AT_byte_size, 0, Size);
+
+  // Add source line info if available and TyDesc is not a forward declaration.
+  if (!DTy.isForwardDecl())
+    addSourceLine(&Buffer, DTy);
+}
+
+/// constructTypeDIE - Construct type DIE from DICompositeType.
+void CompileUnit::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
+  // Get core information.
+  StringRef Name = CTy.getName();
+
+  uint64_t Size = CTy.getSizeInBits() >> 3;
+  unsigned Tag = CTy.getTag();
+  Buffer.setTag(Tag);
+
+  switch (Tag) {
+  case dwarf::DW_TAG_vector_type:
+  case dwarf::DW_TAG_array_type:
+    constructArrayTypeDIE(Buffer, &CTy);
+    break;
+  case dwarf::DW_TAG_enumeration_type: {
+    DIArray Elements = CTy.getTypeArray();
+
+    // Add enumerators to enumeration type.
+    for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
+      DIE *ElemDie = NULL;
+      DIDescriptor Enum(Elements.getElement(i));
+      if (Enum.isEnumerator()) {
+        ElemDie = constructEnumTypeDIE(DIEnumerator(Enum));
+        Buffer.addChild(ElemDie);
+      }
+    }
+  }
+    break;
+  case dwarf::DW_TAG_subroutine_type: {
+    // Add return type.
+    DIArray Elements = CTy.getTypeArray();
+    DIDescriptor RTy = Elements.getElement(0);
+    addType(&Buffer, DIType(RTy));
+
+    bool isPrototyped = true;
+    // Add arguments.
+    for (unsigned i = 1, N = Elements.getNumElements(); i < N; ++i) {
+      DIDescriptor Ty = Elements.getElement(i);
+      if (Ty.isUnspecifiedParameter()) {
+        DIE *Arg = new DIE(dwarf::DW_TAG_unspecified_parameters);
+        Buffer.addChild(Arg);
+        isPrototyped = false;
+      } else {
+        DIE *Arg = new DIE(dwarf::DW_TAG_formal_parameter);
+        addType(Arg, DIType(Ty));
+        Buffer.addChild(Arg);
+      }
+    }
+    // Add prototype flag.
+    if (isPrototyped)
+      addUInt(&Buffer, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag, 1);
+  }
+    break;
+  case dwarf::DW_TAG_structure_type:
+  case dwarf::DW_TAG_union_type:
+  case dwarf::DW_TAG_class_type: {
+    // Add elements to structure type.
+    DIArray Elements = CTy.getTypeArray();
+
+    // A forward struct declared type may not have elements available.
+    unsigned N = Elements.getNumElements();
+    if (N == 0)
+      break;
+
+    // Add elements to structure type.
+    for (unsigned i = 0; i < N; ++i) {
+      DIDescriptor Element = Elements.getElement(i);
+      DIE *ElemDie = NULL;
+      if (Element.isSubprogram()) {
+        DISubprogram SP(Element);
+        ElemDie = DD->createSubprogramDIE(DISubprogram(Element));
+        if (SP.isProtected())
+          addUInt(ElemDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_flag,
+                  dwarf::DW_ACCESS_protected);
+        else if (SP.isPrivate())
+          addUInt(ElemDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_flag,
+                  dwarf::DW_ACCESS_private);
+        else 
+          addUInt(ElemDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_flag,
+            dwarf::DW_ACCESS_public);
+        if (SP.isExplicit())
+          addUInt(ElemDie, dwarf::DW_AT_explicit, dwarf::DW_FORM_flag, 1);
+      }
+      else if (Element.isVariable()) {
+        DIVariable DV(Element);
+        ElemDie = new DIE(dwarf::DW_TAG_variable);
+        addString(ElemDie, dwarf::DW_AT_name, dwarf::DW_FORM_string,
+                  DV.getName());
+        addType(ElemDie, DV.getType());
+        addUInt(ElemDie, dwarf::DW_AT_declaration, dwarf::DW_FORM_flag, 1);
+        addUInt(ElemDie, dwarf::DW_AT_external, dwarf::DW_FORM_flag, 1);
+        addSourceLine(ElemDie, DV);
+      } else if (Element.isDerivedType())
+        ElemDie = createMemberDIE(DIDerivedType(Element));
+      else
+        continue;
+      Buffer.addChild(ElemDie);
+    }
+
+    if (CTy.isAppleBlockExtension())
+      addUInt(&Buffer, dwarf::DW_AT_APPLE_block, dwarf::DW_FORM_flag, 1);
+
+    unsigned RLang = CTy.getRunTimeLang();
+    if (RLang)
+      addUInt(&Buffer, dwarf::DW_AT_APPLE_runtime_class,
+              dwarf::DW_FORM_data1, RLang);
+
+    DICompositeType ContainingType = CTy.getContainingType();
+    if (DIDescriptor(ContainingType).isCompositeType())
+      addDIEEntry(&Buffer, dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4,
+                  getOrCreateTypeDIE(DIType(ContainingType)));
+    else {
+      DIDescriptor Context = CTy.getContext();
+      addToContextOwner(&Buffer, Context);
+    }
+
+    if (Tag == dwarf::DW_TAG_class_type) 
+      addTemplateParams(Buffer, CTy.getTemplateParams());
+
+    break;
+  }
+  default:
+    break;
+  }
+
+  // Add name if not anonymous or intermediate type.
+  if (!Name.empty())
+    addString(&Buffer, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
+
+  if (Tag == dwarf::DW_TAG_enumeration_type || Tag == dwarf::DW_TAG_class_type
+      || Tag == dwarf::DW_TAG_structure_type || Tag == dwarf::DW_TAG_union_type)
+    {
+    // Add size if non-zero (derived types might be zero-sized.)
+    if (Size)
+      addUInt(&Buffer, dwarf::DW_AT_byte_size, 0, Size);
+    else {
+      // Add zero size if it is not a forward declaration.
+      if (CTy.isForwardDecl())
+        addUInt(&Buffer, dwarf::DW_AT_declaration, dwarf::DW_FORM_flag, 1);
+      else
+        addUInt(&Buffer, dwarf::DW_AT_byte_size, 0, 0);
+    }
+
+    // Add source line info if available.
+    if (!CTy.isForwardDecl())
+      addSourceLine(&Buffer, CTy);
+  }
+}
+
+/// getOrCreateTemplateTypeParameterDIE - Find existing DIE or create new DIE 
+/// for the given DITemplateTypeParameter.
+DIE *
+CompileUnit::getOrCreateTemplateTypeParameterDIE(DITemplateTypeParameter TP) {
+  DIE *ParamDIE = getDIE(TP);
+  if (ParamDIE)
+    return ParamDIE;
+
+  ParamDIE = new DIE(dwarf::DW_TAG_template_type_parameter);
+  addType(ParamDIE, TP.getType());
+  addString(ParamDIE, dwarf::DW_AT_name, dwarf::DW_FORM_string, TP.getName());
+  return ParamDIE;
+}
+
+/// getOrCreateTemplateValueParameterDIE - Find existing DIE or create new DIE 
+/// for the given DITemplateValueParameter.
+DIE *
+CompileUnit::getOrCreateTemplateValueParameterDIE(DITemplateValueParameter TPV) {
+  DIE *ParamDIE = getDIE(TPV);
+  if (ParamDIE)
+    return ParamDIE;
+
+  ParamDIE = new DIE(dwarf::DW_TAG_template_value_parameter);
+  addType(ParamDIE, TPV.getType());
+  if (!TPV.getName().empty())
+    addString(ParamDIE, dwarf::DW_AT_name, dwarf::DW_FORM_string, TPV.getName());
+  addUInt(ParamDIE, dwarf::DW_AT_const_value, dwarf::DW_FORM_udata, 
+          TPV.getValue());
+  return ParamDIE;
+}
+
+/// constructSubrangeDIE - Construct subrange DIE from DISubrange.
+void CompileUnit::constructSubrangeDIE(DIE &Buffer, DISubrange SR, DIE *IndexTy){
+  DIE *DW_Subrange = new DIE(dwarf::DW_TAG_subrange_type);
+  addDIEEntry(DW_Subrange, dwarf::DW_AT_type, dwarf::DW_FORM_ref4, IndexTy);
+  int64_t L = SR.getLo();
+  int64_t H = SR.getHi();
+
+  // The L value defines the lower bounds which is typically zero for C/C++. The
+  // H value is the upper bounds.  Values are 64 bit.  H - L + 1 is the size
+  // of the array. If L > H then do not emit DW_AT_lower_bound and 
+  // DW_AT_upper_bound attributes. If L is zero and H is also zero then the
+  // array has one element and in such case do not emit lower bound.
+
+  if (L > H) {
+    Buffer.addChild(DW_Subrange);
+    return;
+  }
+  if (L)
+    addSInt(DW_Subrange, dwarf::DW_AT_lower_bound, 0, L);
+  addSInt(DW_Subrange, dwarf::DW_AT_upper_bound, 0, H);
+  Buffer.addChild(DW_Subrange);
+}
+
+/// constructArrayTypeDIE - Construct array type DIE from DICompositeType.
+void CompileUnit::constructArrayTypeDIE(DIE &Buffer,
+                                        DICompositeType *CTy) {
+  Buffer.setTag(dwarf::DW_TAG_array_type);
+  if (CTy->getTag() == dwarf::DW_TAG_vector_type)
+    addUInt(&Buffer, dwarf::DW_AT_GNU_vector, dwarf::DW_FORM_flag, 1);
+
+  // Emit derived type.
+  addType(&Buffer, CTy->getTypeDerivedFrom());
+  DIArray Elements = CTy->getTypeArray();
+
+  // Get an anonymous type for index type.
+  DIE *IdxTy = getIndexTyDie();
+  if (!IdxTy) {
+    // Construct an anonymous type for index type.
+    IdxTy = new DIE(dwarf::DW_TAG_base_type);
+    addUInt(IdxTy, dwarf::DW_AT_byte_size, 0, sizeof(int32_t));
+    addUInt(IdxTy, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1,
+            dwarf::DW_ATE_signed);
+    addDie(IdxTy);
+    setIndexTyDie(IdxTy);
+  }
+
+  // Add subranges to array type.
+  for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
+    DIDescriptor Element = Elements.getElement(i);
+    if (Element.getTag() == dwarf::DW_TAG_subrange_type)
+      constructSubrangeDIE(Buffer, DISubrange(Element), IdxTy);
+  }
+}
+
+/// constructEnumTypeDIE - Construct enum type DIE from DIEnumerator.
+DIE *CompileUnit::constructEnumTypeDIE(DIEnumerator ETy) {
+  DIE *Enumerator = new DIE(dwarf::DW_TAG_enumerator);
+  StringRef Name = ETy.getName();
+  addString(Enumerator, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
+  int64_t Value = ETy.getEnumValue();
+  addSInt(Enumerator, dwarf::DW_AT_const_value, dwarf::DW_FORM_sdata, Value);
+  return Enumerator;
+}
+
+/// createMemberDIE - Create new member DIE.
+DIE *CompileUnit::createMemberDIE(DIDerivedType DT) {
+  DIE *MemberDie = new DIE(DT.getTag());
+  StringRef Name = DT.getName();
+  if (!Name.empty())
+    addString(MemberDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
+
+  addType(MemberDie, DT.getTypeDerivedFrom());
+
+  addSourceLine(MemberDie, DT);
+
+  DIEBlock *MemLocationDie = new (DIEValueAllocator) DIEBlock();
+  addUInt(MemLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_plus_uconst);
+
+  uint64_t Size = DT.getSizeInBits();
+  uint64_t FieldSize = DT.getOriginalTypeSize();
+
+  if (Size != FieldSize) {
+    // Handle bitfield.
+    addUInt(MemberDie, dwarf::DW_AT_byte_size, 0, DT.getOriginalTypeSize()>>3);
+    addUInt(MemberDie, dwarf::DW_AT_bit_size, 0, DT.getSizeInBits());
+
+    uint64_t Offset = DT.getOffsetInBits();
+    uint64_t AlignMask = ~(DT.getAlignInBits() - 1);
+    uint64_t HiMark = (Offset + FieldSize) & AlignMask;
+    uint64_t FieldOffset = (HiMark - FieldSize);
+    Offset -= FieldOffset;
+
+    // Maybe we need to work from the other end.
+    if (Asm->getTargetData().isLittleEndian())
+      Offset = FieldSize - (Offset + Size);
+    addUInt(MemberDie, dwarf::DW_AT_bit_offset, 0, Offset);
+
+    // Here WD_AT_data_member_location points to the anonymous
+    // field that includes this bit field.
+    addUInt(MemLocationDie, 0, dwarf::DW_FORM_udata, FieldOffset >> 3);
+
+  } else
+    // This is not a bitfield.
+    addUInt(MemLocationDie, 0, dwarf::DW_FORM_udata, DT.getOffsetInBits() >> 3);
+
+  if (DT.getTag() == dwarf::DW_TAG_inheritance
+      && DT.isVirtual()) {
+
+    // For C++, virtual base classes are not at fixed offset. Use following
+    // expression to extract appropriate offset from vtable.
+    // BaseAddr = ObAddr + *((*ObAddr) - Offset)
+
+    DIEBlock *VBaseLocationDie = new (DIEValueAllocator) DIEBlock();
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_dup);
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_udata, DT.getOffsetInBits());
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_minus);
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
+    addUInt(VBaseLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_plus);
+
+    addBlock(MemberDie, dwarf::DW_AT_data_member_location, 0,
+             VBaseLocationDie);
+  } else
+    addBlock(MemberDie, dwarf::DW_AT_data_member_location, 0, MemLocationDie);
+
+  if (DT.isProtected())
+    addUInt(MemberDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_flag,
+            dwarf::DW_ACCESS_protected);
+  else if (DT.isPrivate())
+    addUInt(MemberDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_flag,
+            dwarf::DW_ACCESS_private);
+  // Otherwise C++ member and base classes are considered public.
+  else if (DT.getCompileUnit().getLanguage() == dwarf::DW_LANG_C_plus_plus)
+    addUInt(MemberDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_flag,
+            dwarf::DW_ACCESS_public);
+  if (DT.isVirtual())
+    addUInt(MemberDie, dwarf::DW_AT_virtuality, dwarf::DW_FORM_flag,
+            dwarf::DW_VIRTUALITY_virtual);
+  return MemberDie;
+}