lib/CodeGen/AsmPrinter/DIEHash.cpp - fp2-dev/platform/external/llvm - Gitiles

 //===-- llvm/CodeGen/DIEHash.cpp - Dwarf Hashing Framework ----------------===//
 //
 //                     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 DWARF4 hashing of DIEs.
 //
 //===----------------------------------------------------------------------===//

 #define DEBUG_TYPE "dwarfdebug"

 #include "DIE.h"
 #include "DIEHash.h"
 #include "DwarfCompileUnit.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/MD5.h"
 #include "llvm/Support/raw_ostream.h"

 using namespace llvm;

 /// \brief Grabs the string in whichever attribute is passed in and returns
 /// a reference to it.
 static StringRef getDIEStringAttr(DIE *Die, uint16_t Attr) {
   const SmallVectorImpl<DIEValue *> &Values = Die->getValues();
   const DIEAbbrev &Abbrevs = Die->getAbbrev();

   // Iterate through all the attributes until we find the one we're
   // looking for, if we can't find it return an empty string.
   for (size_t i = 0; i < Values.size(); ++i) {
     if (Abbrevs.getData()[i].getAttribute() == Attr) {
       DIEValue *V = Values[i];
       assert(isa<DIEString>(V) && "String requested. Not a string.");
       DIEString *S = cast<DIEString>(V);
       return S->getString();
     }
   }
   return StringRef("");
 }

 /// \brief Adds the string in \p Str to the hash. This also hashes
 /// a trailing NULL with the string.
 void DIEHash::addString(StringRef Str) {
   DEBUG(dbgs() << "Adding string " << Str << " to hash.\n");
   Hash.update(Str);
   Hash.update(makeArrayRef((uint8_t)'\0'));
 }

 // FIXME: The LEB128 routines are copied and only slightly modified out of
 // LEB128.h.

 /// \brief Adds the unsigned in \p Value to the hash encoded as a ULEB128.
 void DIEHash::addULEB128(uint64_t Value) {
   DEBUG(dbgs() << "Adding ULEB128 " << Value << " to hash.\n");
   do {
     uint8_t Byte = Value & 0x7f;
     Value >>= 7;
     if (Value != 0)
       Byte |= 0x80; // Mark this byte to show that more bytes will follow.
     Hash.update(Byte);
   } while (Value != 0);
 }

 void DIEHash::addSLEB128(int64_t Value) {
   DEBUG(dbgs() << "Adding ULEB128 " << Value << " to hash.\n");
   bool More;
   do {
     uint8_t Byte = Value & 0x7f;
     Value >>= 7;
     More = !((((Value == 0 ) && ((Byte & 0x40) == 0)) ||
               ((Value == -1) && ((Byte & 0x40) != 0))));
     if (More)
       Byte |= 0x80; // Mark this byte to show that more bytes will follow.
     Hash.update(Byte);
   } while (More);
 }

 /// \brief Including \p Parent adds the context of Parent to the hash..
 void DIEHash::addParentContext(DIE *Parent) {

   DEBUG(dbgs() << "Adding parent context to hash...\n");

   // [7.27.2] For each surrounding type or namespace beginning with the
   // outermost such construct...
   SmallVector<DIE *, 1> Parents;
   while (Parent->getTag() != dwarf::DW_TAG_compile_unit) {
     Parents.push_back(Parent);
     Parent = Parent->getParent();
   }

   // Reverse iterate over our list to go from the outermost construct to the
   // innermost.
   for (SmallVectorImpl<DIE *>::reverse_iterator I = Parents.rbegin(),
                                                 E = Parents.rend();
        I != E; ++I) {
     DIE *Die = *I;

     // ... Append the letter "C" to the sequence...
     addULEB128('C');

     // ... Followed by the DWARF tag of the construct...
     addULEB128(Die->getTag());

     // ... Then the name, taken from the DW_AT_name attribute.
     StringRef Name = getDIEStringAttr(Die, dwarf::DW_AT_name);
     DEBUG(dbgs() << "... adding context: " << Name << "\n");
     if (!Name.empty())
       addString(Name);
   }
 }

 // Collect all of the attributes for a particular DIE in single structure.
 void DIEHash::collectAttributes(DIE *Die, DIEAttrs &Attrs) {
   const SmallVectorImpl<DIEValue *> &Values = Die->getValues();
   const DIEAbbrev &Abbrevs = Die->getAbbrev();

 #define COLLECT_ATTR(NAME)                                                     \
   case dwarf::NAME:                                                            \
     Attrs.NAME.Val = Values[i];                                                \
     Attrs.NAME.Desc = &Abbrevs.getData()[i];                                   \
     break

   for (size_t i = 0, e = Values.size(); i != e; ++i) {
     DEBUG(dbgs() << "Attribute: "
                  << dwarf::AttributeString(Abbrevs.getData()[i].getAttribute())
                  << " added.\n");
     switch (Abbrevs.getData()[i].getAttribute()) {
     COLLECT_ATTR(DW_AT_name);
     COLLECT_ATTR(DW_AT_accessibility);
     COLLECT_ATTR(DW_AT_address_class);
     COLLECT_ATTR(DW_AT_allocated);
     COLLECT_ATTR(DW_AT_artificial);
     COLLECT_ATTR(DW_AT_associated);
     COLLECT_ATTR(DW_AT_binary_scale);
     COLLECT_ATTR(DW_AT_bit_offset);
     COLLECT_ATTR(DW_AT_bit_size);
     COLLECT_ATTR(DW_AT_bit_stride);
     COLLECT_ATTR(DW_AT_byte_size);
     COLLECT_ATTR(DW_AT_byte_stride);
     COLLECT_ATTR(DW_AT_const_expr);
     COLLECT_ATTR(DW_AT_const_value);
     COLLECT_ATTR(DW_AT_containing_type);
     COLLECT_ATTR(DW_AT_count);
     COLLECT_ATTR(DW_AT_data_bit_offset);
     COLLECT_ATTR(DW_AT_data_location);
     COLLECT_ATTR(DW_AT_data_member_location);
     COLLECT_ATTR(DW_AT_decimal_scale);
     COLLECT_ATTR(DW_AT_decimal_sign);
     COLLECT_ATTR(DW_AT_default_value);
     COLLECT_ATTR(DW_AT_digit_count);
     COLLECT_ATTR(DW_AT_discr);
     COLLECT_ATTR(DW_AT_discr_list);
     COLLECT_ATTR(DW_AT_discr_value);
     COLLECT_ATTR(DW_AT_encoding);
     COLLECT_ATTR(DW_AT_enum_class);
     COLLECT_ATTR(DW_AT_endianity);
     COLLECT_ATTR(DW_AT_explicit);
     COLLECT_ATTR(DW_AT_is_optional);
     COLLECT_ATTR(DW_AT_location);
     COLLECT_ATTR(DW_AT_lower_bound);
     COLLECT_ATTR(DW_AT_mutable);
     COLLECT_ATTR(DW_AT_ordering);
     COLLECT_ATTR(DW_AT_picture_string);
     COLLECT_ATTR(DW_AT_prototyped);
     COLLECT_ATTR(DW_AT_small);
     COLLECT_ATTR(DW_AT_segment);
     COLLECT_ATTR(DW_AT_string_length);
     COLLECT_ATTR(DW_AT_threads_scaled);
     COLLECT_ATTR(DW_AT_upper_bound);
     COLLECT_ATTR(DW_AT_use_location);
     COLLECT_ATTR(DW_AT_use_UTF8);
     COLLECT_ATTR(DW_AT_variable_parameter);
     COLLECT_ATTR(DW_AT_virtuality);
     COLLECT_ATTR(DW_AT_visibility);
     COLLECT_ATTR(DW_AT_vtable_elem_location);
     COLLECT_ATTR(DW_AT_type);
     default:
       break;
     }
   }
 }

 // Hash an individual attribute \param Attr based on the type of attribute and
 // the form.
 void DIEHash::hashAttribute(AttrEntry Attr, dwarf::Tag Tag) {
   const DIEValue *Value = Attr.Val;
   const DIEAbbrevData *Desc = Attr.Desc;

   // 7.27 Step 3
   // ... An attribute that refers to another type entry T is processed as
   // follows:
   if (const DIEEntry *EntryAttr = dyn_cast<DIEEntry>(Value)) {
     DIE *Entry = EntryAttr->getEntry();

     // Step 5
     // If the tag in Step 3 is one of ...
     if (Tag == dwarf::DW_TAG_pointer_type) {
       // ... and the referenced type (via the DW_AT_type or DW_AT_friend
       // attribute) ...
       assert(Desc->getAttribute() == dwarf::DW_AT_type ||
              Desc->getAttribute() == dwarf::DW_AT_friend);
       // [FIXME] ... has a DW_AT_name attribute,
       // append the letter 'N'
       addULEB128('N');

       // the DWARF attribute code (DW_AT_type or DW_AT_friend),
       addULEB128(Desc->getAttribute());

       // the context of the tag,
       if (DIE *Parent = Entry->getParent())
         addParentContext(Parent);

       // the letter 'E',
       addULEB128('E');

       // and the name of the type.
       addString(getDIEStringAttr(Entry, dwarf::DW_AT_name));

       // FIXME:
       // For DW_TAG_friend, if the referenced entry is the DW_TAG_subprogram,
       // the context is omitted and the name to be used is the ABI-specific name
       // of the subprogram (e.g., the mangled linker name).
       return;
     }

     unsigned &DieNumber = Numbering[Entry];
     if (DieNumber) {
       // a) If T is in the list of [previously hashed types], use the letter
       // 'R' as the marker
       addULEB128('R');

       addULEB128(Desc->getAttribute());

       // and use the unsigned LEB128 encoding of [the index of T in the
       // list] as the attribute value;
       addULEB128(DieNumber);
       return;
     }

     // otherwise, b) use the letter 'T' as a the marker, ...
     addULEB128('T');

     addULEB128(Desc->getAttribute());

     // ... process the type T recursively by performing Steps 2 through 7, and
     // use the result as the attribute value.
     DieNumber = Numbering.size();
     computeHash(Entry);
     return;
   }

   // Other attribute values use the letter 'A' as the marker, ...
   addULEB128('A');

   addULEB128(Desc->getAttribute());

   // ... and the value consists of the form code (encoded as an unsigned LEB128
   // value) followed by the encoding of the value according to the form code. To
   // ensure reproducibility of the signature, the set of forms used in the
   // signature computation is limited to the following: DW_FORM_sdata,
   // DW_FORM_flag, DW_FORM_string, and DW_FORM_block.
   switch (Desc->getForm()) {
   case dwarf::DW_FORM_string:
     llvm_unreachable(
         "Add support for DW_FORM_string if we ever start emitting them again");
   case dwarf::DW_FORM_GNU_str_index:
   case dwarf::DW_FORM_strp:
     addULEB128(dwarf::DW_FORM_string);
     addString(cast<DIEString>(Value)->getString());
     break;
   case dwarf::DW_FORM_data1:
   case dwarf::DW_FORM_data2:
   case dwarf::DW_FORM_data4:
   case dwarf::DW_FORM_data8:
   case dwarf::DW_FORM_udata:
     addULEB128(dwarf::DW_FORM_sdata);
     addSLEB128((int64_t)cast<DIEInteger>(Value)->getValue());
     break;
   default:
     llvm_unreachable("Add support for additional forms");
   }
 }

 // Go through the attributes from \param Attrs in the order specified in 7.27.4
 // and hash them.
 void DIEHash::hashAttributes(const DIEAttrs &Attrs, dwarf::Tag Tag) {
 #define ADD_ATTR(ATTR)                                                         \
   {                                                                            \
     if (ATTR.Val != 0)                                                         \
       hashAttribute(ATTR, Tag);                                                \
   }

   ADD_ATTR(Attrs.DW_AT_name);
   ADD_ATTR(Attrs.DW_AT_accessibility);
   ADD_ATTR(Attrs.DW_AT_address_class);
   ADD_ATTR(Attrs.DW_AT_allocated);
   ADD_ATTR(Attrs.DW_AT_artificial);
   ADD_ATTR(Attrs.DW_AT_associated);
   ADD_ATTR(Attrs.DW_AT_binary_scale);
   ADD_ATTR(Attrs.DW_AT_bit_offset);
   ADD_ATTR(Attrs.DW_AT_bit_size);
   ADD_ATTR(Attrs.DW_AT_bit_stride);
   ADD_ATTR(Attrs.DW_AT_byte_size);
   ADD_ATTR(Attrs.DW_AT_byte_stride);
   ADD_ATTR(Attrs.DW_AT_const_expr);
   ADD_ATTR(Attrs.DW_AT_const_value);
   ADD_ATTR(Attrs.DW_AT_containing_type);
   ADD_ATTR(Attrs.DW_AT_count);
   ADD_ATTR(Attrs.DW_AT_data_bit_offset);
   ADD_ATTR(Attrs.DW_AT_data_location);
   ADD_ATTR(Attrs.DW_AT_data_member_location);
   ADD_ATTR(Attrs.DW_AT_decimal_scale);
   ADD_ATTR(Attrs.DW_AT_decimal_sign);
   ADD_ATTR(Attrs.DW_AT_default_value);
   ADD_ATTR(Attrs.DW_AT_digit_count);
   ADD_ATTR(Attrs.DW_AT_discr);
   ADD_ATTR(Attrs.DW_AT_discr_list);
   ADD_ATTR(Attrs.DW_AT_discr_value);
   ADD_ATTR(Attrs.DW_AT_encoding);
   ADD_ATTR(Attrs.DW_AT_enum_class);
   ADD_ATTR(Attrs.DW_AT_endianity);
   ADD_ATTR(Attrs.DW_AT_explicit);
   ADD_ATTR(Attrs.DW_AT_is_optional);
   ADD_ATTR(Attrs.DW_AT_location);
   ADD_ATTR(Attrs.DW_AT_lower_bound);
   ADD_ATTR(Attrs.DW_AT_mutable);
   ADD_ATTR(Attrs.DW_AT_ordering);
   ADD_ATTR(Attrs.DW_AT_picture_string);
   ADD_ATTR(Attrs.DW_AT_prototyped);
   ADD_ATTR(Attrs.DW_AT_small);
   ADD_ATTR(Attrs.DW_AT_segment);
   ADD_ATTR(Attrs.DW_AT_string_length);
   ADD_ATTR(Attrs.DW_AT_threads_scaled);
   ADD_ATTR(Attrs.DW_AT_upper_bound);
   ADD_ATTR(Attrs.DW_AT_use_location);
   ADD_ATTR(Attrs.DW_AT_use_UTF8);
   ADD_ATTR(Attrs.DW_AT_variable_parameter);
   ADD_ATTR(Attrs.DW_AT_virtuality);
   ADD_ATTR(Attrs.DW_AT_visibility);
   ADD_ATTR(Attrs.DW_AT_vtable_elem_location);
   ADD_ATTR(Attrs.DW_AT_type);

   // FIXME: Add the extended attributes.
 }

 // Add all of the attributes for \param Die to the hash.
 void DIEHash::addAttributes(DIE *Die) {
   DIEAttrs Attrs = {};
   collectAttributes(Die, Attrs);
   hashAttributes(Attrs, Die->getTag());
 }

 // Compute the hash of a DIE. This is based on the type signature computation
 // given in section 7.27 of the DWARF4 standard. It is the md5 hash of a
 // flattened description of the DIE.
 void DIEHash::computeHash(DIE *Die) {
   // Append the letter 'D', followed by the DWARF tag of the DIE.
   addULEB128('D');
   addULEB128(Die->getTag());

   // Add each of the attributes of the DIE.
   addAttributes(Die);

   // Then hash each of the children of the DIE.
   for (std::vector<DIE *>::const_iterator I = Die->getChildren().begin(),
                                           E = Die->getChildren().end();
        I != E; ++I)
     computeHash(*I);

   // Following the last (or if there are no children), append a zero byte.
   Hash.update(makeArrayRef((uint8_t)'\0'));
 }

 /// This is based on the type signature computation given in section 7.27 of the
 /// DWARF4 standard. It is the md5 hash of a flattened description of the DIE
 /// with the exception that we are hashing only the context and the name of the
 /// type.
 uint64_t DIEHash::computeDIEODRSignature(DIE *Die) {

   // Add the contexts to the hash. We won't be computing the ODR hash for
   // function local types so it's safe to use the generic context hashing
   // algorithm here.
   // FIXME: If we figure out how to account for linkage in some way we could
   // actually do this with a slight modification to the parent hash algorithm.
   DIE *Parent = Die->getParent();
   if (Parent)
     addParentContext(Parent);

   // Add the current DIE information.

   // Add the DWARF tag of the DIE.
   addULEB128(Die->getTag());

   // Add the name of the type to the hash.
   addString(getDIEStringAttr(Die, dwarf::DW_AT_name));

   // Now get the result.
   MD5::MD5Result Result;
   Hash.final(Result);

   // ... take the least significant 8 bytes and return those. Our MD5
   // implementation always returns its results in little endian, swap bytes
   // appropriately.
   return *reinterpret_cast<support::ulittle64_t *>(Result + 8);
 }

 /// This is based on the type signature computation given in section 7.27 of the
 /// DWARF4 standard. It is an md5 hash of the flattened description of the DIE
 /// with the inclusion of the full CU and all top level CU entities.
 // TODO: Initialize the type chain at 0 instead of 1 for CU signatures.
 uint64_t DIEHash::computeCUSignature(DIE *Die) {
   Numbering.clear();
   Numbering[Die] = 1;

   // Hash the DIE.
   computeHash(Die);

   // Now return the result.
   MD5::MD5Result Result;
   Hash.final(Result);

   // ... take the least significant 8 bytes and return those. Our MD5
   // implementation always returns its results in little endian, swap bytes
   // appropriately.
   return *reinterpret_cast<support::ulittle64_t *>(Result + 8);
 }

 /// This is based on the type signature computation given in section 7.27 of the
 /// DWARF4 standard. It is an md5 hash of the flattened description of the DIE
 /// with the inclusion of additional forms not specifically called out in the
 /// standard.
 uint64_t DIEHash::computeTypeSignature(DIE *Die) {
   Numbering.clear();
   Numbering[Die] = 1;

   if (DIE *Parent = Die->getParent())
     addParentContext(Parent);

   // Hash the DIE.
   computeHash(Die);

   // Now return the result.
   MD5::MD5Result Result;
   Hash.final(Result);

   // ... take the least significant 8 bytes and return those. Our MD5
   // implementation always returns its results in little endian, swap bytes
   // appropriately.
   return *reinterpret_cast<support::ulittle64_t *>(Result + 8);
 }
	//===-- llvm/CodeGen/DIEHash.cpp - Dwarf Hashing Framework ----------------===//
	//
	// 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 DWARF4 hashing of DIEs.
	//
	//===----------------------------------------------------------------------===//

	#define DEBUG_TYPE "dwarfdebug"

	#include "DIE.h"
	#include "DIEHash.h"
	#include "DwarfCompileUnit.h"
	#include "llvm/ADT/ArrayRef.h"
	#include "llvm/ADT/StringRef.h"
	#include "llvm/Support/Debug.h"
	#include "llvm/Support/Dwarf.h"
	#include "llvm/Support/Endian.h"
	#include "llvm/Support/MD5.h"
	#include "llvm/Support/raw_ostream.h"

	using namespace llvm;

	/// \brief Grabs the string in whichever attribute is passed in and returns
	/// a reference to it.
	static StringRef getDIEStringAttr(DIE *Die, uint16_t Attr) {
	const SmallVectorImpl<DIEValue *> &Values = Die->getValues();
	const DIEAbbrev &Abbrevs = Die->getAbbrev();

	// Iterate through all the attributes until we find the one we're
	// looking for, if we can't find it return an empty string.
	for (size_t i = 0; i < Values.size(); ++i) {
	if (Abbrevs.getData()[i].getAttribute() == Attr) {
	DIEValue *V = Values[i];
	assert(isa<DIEString>(V) && "String requested. Not a string.");
	DIEString *S = cast<DIEString>(V);
	return S->getString();
	}
	}
	return StringRef("");
	}

	/// \brief Adds the string in \p Str to the hash. This also hashes
	/// a trailing NULL with the string.
	void DIEHash::addString(StringRef Str) {
	DEBUG(dbgs() << "Adding string " << Str << " to hash.\n");
	Hash.update(Str);
	Hash.update(makeArrayRef((uint8_t)'\0'));
	}

	// FIXME: The LEB128 routines are copied and only slightly modified out of
	// LEB128.h.

	/// \brief Adds the unsigned in \p Value to the hash encoded as a ULEB128.
	void DIEHash::addULEB128(uint64_t Value) {
	DEBUG(dbgs() << "Adding ULEB128 " << Value << " to hash.\n");
	do {
	uint8_t Byte = Value & 0x7f;
	Value >>= 7;
	if (Value != 0)
	Byte \|= 0x80; // Mark this byte to show that more bytes will follow.
	Hash.update(Byte);
	} while (Value != 0);
	}

	void DIEHash::addSLEB128(int64_t Value) {
	DEBUG(dbgs() << "Adding ULEB128 " << Value << " to hash.\n");
	bool More;
	do {
	uint8_t Byte = Value & 0x7f;
	Value >>= 7;
	More = !((((Value == 0 ) && ((Byte & 0x40) == 0)) \|\|
	((Value == -1) && ((Byte & 0x40) != 0))));
	if (More)
	Byte \|= 0x80; // Mark this byte to show that more bytes will follow.
	Hash.update(Byte);
	} while (More);
	}

	/// \brief Including \p Parent adds the context of Parent to the hash..
	void DIEHash::addParentContext(DIE *Parent) {

	DEBUG(dbgs() << "Adding parent context to hash...\n");

	// [7.27.2] For each surrounding type or namespace beginning with the
	// outermost such construct...
	SmallVector<DIE *, 1> Parents;
	while (Parent->getTag() != dwarf::DW_TAG_compile_unit) {
	Parents.push_back(Parent);
	Parent = Parent->getParent();
	}

	// Reverse iterate over our list to go from the outermost construct to the
	// innermost.
	for (SmallVectorImpl<DIE *>::reverse_iterator I = Parents.rbegin(),
	E = Parents.rend();
	I != E; ++I) {
	DIE Die = I;

	// ... Append the letter "C" to the sequence...
	addULEB128('C');

	// ... Followed by the DWARF tag of the construct...
	addULEB128(Die->getTag());

	// ... Then the name, taken from the DW_AT_name attribute.
	StringRef Name = getDIEStringAttr(Die, dwarf::DW_AT_name);
	DEBUG(dbgs() << "... adding context: " << Name << "\n");
	if (!Name.empty())
	addString(Name);
	}
	}

	// Collect all of the attributes for a particular DIE in single structure.
	void DIEHash::collectAttributes(DIE *Die, DIEAttrs &Attrs) {
	const SmallVectorImpl<DIEValue *> &Values = Die->getValues();
	const DIEAbbrev &Abbrevs = Die->getAbbrev();

	#define COLLECT_ATTR(NAME) \
	case dwarf::NAME: \
	Attrs.NAME.Val = Values[i]; \
	Attrs.NAME.Desc = &Abbrevs.getData()[i]; \
	break

	for (size_t i = 0, e = Values.size(); i != e; ++i) {
	DEBUG(dbgs() << "Attribute: "
	<< dwarf::AttributeString(Abbrevs.getData()[i].getAttribute())
	<< " added.\n");
	switch (Abbrevs.getData()[i].getAttribute()) {
	COLLECT_ATTR(DW_AT_name);
	COLLECT_ATTR(DW_AT_accessibility);
	COLLECT_ATTR(DW_AT_address_class);
	COLLECT_ATTR(DW_AT_allocated);
	COLLECT_ATTR(DW_AT_artificial);
	COLLECT_ATTR(DW_AT_associated);
	COLLECT_ATTR(DW_AT_binary_scale);
	COLLECT_ATTR(DW_AT_bit_offset);
	COLLECT_ATTR(DW_AT_bit_size);
	COLLECT_ATTR(DW_AT_bit_stride);
	COLLECT_ATTR(DW_AT_byte_size);
	COLLECT_ATTR(DW_AT_byte_stride);
	COLLECT_ATTR(DW_AT_const_expr);
	COLLECT_ATTR(DW_AT_const_value);
	COLLECT_ATTR(DW_AT_containing_type);
	COLLECT_ATTR(DW_AT_count);
	COLLECT_ATTR(DW_AT_data_bit_offset);
	COLLECT_ATTR(DW_AT_data_location);
	COLLECT_ATTR(DW_AT_data_member_location);
	COLLECT_ATTR(DW_AT_decimal_scale);
	COLLECT_ATTR(DW_AT_decimal_sign);
	COLLECT_ATTR(DW_AT_default_value);
	COLLECT_ATTR(DW_AT_digit_count);
	COLLECT_ATTR(DW_AT_discr);
	COLLECT_ATTR(DW_AT_discr_list);
	COLLECT_ATTR(DW_AT_discr_value);
	COLLECT_ATTR(DW_AT_encoding);
	COLLECT_ATTR(DW_AT_enum_class);
	COLLECT_ATTR(DW_AT_endianity);
	COLLECT_ATTR(DW_AT_explicit);
	COLLECT_ATTR(DW_AT_is_optional);
	COLLECT_ATTR(DW_AT_location);
	COLLECT_ATTR(DW_AT_lower_bound);
	COLLECT_ATTR(DW_AT_mutable);
	COLLECT_ATTR(DW_AT_ordering);
	COLLECT_ATTR(DW_AT_picture_string);
	COLLECT_ATTR(DW_AT_prototyped);
	COLLECT_ATTR(DW_AT_small);
	COLLECT_ATTR(DW_AT_segment);
	COLLECT_ATTR(DW_AT_string_length);
	COLLECT_ATTR(DW_AT_threads_scaled);
	COLLECT_ATTR(DW_AT_upper_bound);
	COLLECT_ATTR(DW_AT_use_location);
	COLLECT_ATTR(DW_AT_use_UTF8);
	COLLECT_ATTR(DW_AT_variable_parameter);
	COLLECT_ATTR(DW_AT_virtuality);
	COLLECT_ATTR(DW_AT_visibility);
	COLLECT_ATTR(DW_AT_vtable_elem_location);
	COLLECT_ATTR(DW_AT_type);
	default:
	break;
	}
	}
	}

	// Hash an individual attribute \param Attr based on the type of attribute and
	// the form.
	void DIEHash::hashAttribute(AttrEntry Attr, dwarf::Tag Tag) {
	const DIEValue *Value = Attr.Val;
	const DIEAbbrevData *Desc = Attr.Desc;

	// 7.27 Step 3
	// ... An attribute that refers to another type entry T is processed as
	// follows:
	if (const DIEEntry *EntryAttr = dyn_cast<DIEEntry>(Value)) {
	DIE *Entry = EntryAttr->getEntry();

	// Step 5
	// If the tag in Step 3 is one of ...
	if (Tag == dwarf::DW_TAG_pointer_type) {
	// ... and the referenced type (via the DW_AT_type or DW_AT_friend
	// attribute) ...
	assert(Desc->getAttribute() == dwarf::DW_AT_type \|\|
	Desc->getAttribute() == dwarf::DW_AT_friend);
	// [FIXME] ... has a DW_AT_name attribute,
	// append the letter 'N'
	addULEB128('N');

	// the DWARF attribute code (DW_AT_type or DW_AT_friend),
	addULEB128(Desc->getAttribute());

	// the context of the tag,
	if (DIE *Parent = Entry->getParent())
	addParentContext(Parent);

	// the letter 'E',
	addULEB128('E');

	// and the name of the type.
	addString(getDIEStringAttr(Entry, dwarf::DW_AT_name));

	// FIXME:
	// For DW_TAG_friend, if the referenced entry is the DW_TAG_subprogram,
	// the context is omitted and the name to be used is the ABI-specific name
	// of the subprogram (e.g., the mangled linker name).
	return;
	}

	unsigned &DieNumber = Numbering[Entry];
	if (DieNumber) {
	// a) If T is in the list of [previously hashed types], use the letter
	// 'R' as the marker
	addULEB128('R');

	addULEB128(Desc->getAttribute());

	// and use the unsigned LEB128 encoding of [the index of T in the
	// list] as the attribute value;
	addULEB128(DieNumber);
	return;
	}

	// otherwise, b) use the letter 'T' as a the marker, ...
	addULEB128('T');

	addULEB128(Desc->getAttribute());

	// ... process the type T recursively by performing Steps 2 through 7, and
	// use the result as the attribute value.
	DieNumber = Numbering.size();
	computeHash(Entry);
	return;
	}

	// Other attribute values use the letter 'A' as the marker, ...
	addULEB128('A');

	addULEB128(Desc->getAttribute());

	// ... and the value consists of the form code (encoded as an unsigned LEB128
	// value) followed by the encoding of the value according to the form code. To
	// ensure reproducibility of the signature, the set of forms used in the
	// signature computation is limited to the following: DW_FORM_sdata,
	// DW_FORM_flag, DW_FORM_string, and DW_FORM_block.
	switch (Desc->getForm()) {
	case dwarf::DW_FORM_string:
	llvm_unreachable(
	"Add support for DW_FORM_string if we ever start emitting them again");
	case dwarf::DW_FORM_GNU_str_index:
	case dwarf::DW_FORM_strp:
	addULEB128(dwarf::DW_FORM_string);
	addString(cast<DIEString>(Value)->getString());
	break;
	case dwarf::DW_FORM_data1:
	case dwarf::DW_FORM_data2:
	case dwarf::DW_FORM_data4:
	case dwarf::DW_FORM_data8:
	case dwarf::DW_FORM_udata:
	addULEB128(dwarf::DW_FORM_sdata);
	addSLEB128((int64_t)cast<DIEInteger>(Value)->getValue());
	break;
	default:
	llvm_unreachable("Add support for additional forms");
	}
	}

	// Go through the attributes from \param Attrs in the order specified in 7.27.4
	// and hash them.
	void DIEHash::hashAttributes(const DIEAttrs &Attrs, dwarf::Tag Tag) {
	#define ADD_ATTR(ATTR) \
	{ \
	if (ATTR.Val != 0) \
	hashAttribute(ATTR, Tag); \
	}

	ADD_ATTR(Attrs.DW_AT_name);
	ADD_ATTR(Attrs.DW_AT_accessibility);
	ADD_ATTR(Attrs.DW_AT_address_class);
	ADD_ATTR(Attrs.DW_AT_allocated);
	ADD_ATTR(Attrs.DW_AT_artificial);
	ADD_ATTR(Attrs.DW_AT_associated);
	ADD_ATTR(Attrs.DW_AT_binary_scale);
	ADD_ATTR(Attrs.DW_AT_bit_offset);
	ADD_ATTR(Attrs.DW_AT_bit_size);
	ADD_ATTR(Attrs.DW_AT_bit_stride);
	ADD_ATTR(Attrs.DW_AT_byte_size);
	ADD_ATTR(Attrs.DW_AT_byte_stride);
	ADD_ATTR(Attrs.DW_AT_const_expr);
	ADD_ATTR(Attrs.DW_AT_const_value);
	ADD_ATTR(Attrs.DW_AT_containing_type);
	ADD_ATTR(Attrs.DW_AT_count);
	ADD_ATTR(Attrs.DW_AT_data_bit_offset);
	ADD_ATTR(Attrs.DW_AT_data_location);
	ADD_ATTR(Attrs.DW_AT_data_member_location);
	ADD_ATTR(Attrs.DW_AT_decimal_scale);
	ADD_ATTR(Attrs.DW_AT_decimal_sign);
	ADD_ATTR(Attrs.DW_AT_default_value);
	ADD_ATTR(Attrs.DW_AT_digit_count);
	ADD_ATTR(Attrs.DW_AT_discr);
	ADD_ATTR(Attrs.DW_AT_discr_list);
	ADD_ATTR(Attrs.DW_AT_discr_value);
	ADD_ATTR(Attrs.DW_AT_encoding);
	ADD_ATTR(Attrs.DW_AT_enum_class);
	ADD_ATTR(Attrs.DW_AT_endianity);
	ADD_ATTR(Attrs.DW_AT_explicit);
	ADD_ATTR(Attrs.DW_AT_is_optional);
	ADD_ATTR(Attrs.DW_AT_location);
	ADD_ATTR(Attrs.DW_AT_lower_bound);
	ADD_ATTR(Attrs.DW_AT_mutable);
	ADD_ATTR(Attrs.DW_AT_ordering);
	ADD_ATTR(Attrs.DW_AT_picture_string);
	ADD_ATTR(Attrs.DW_AT_prototyped);
	ADD_ATTR(Attrs.DW_AT_small);
	ADD_ATTR(Attrs.DW_AT_segment);
	ADD_ATTR(Attrs.DW_AT_string_length);
	ADD_ATTR(Attrs.DW_AT_threads_scaled);
	ADD_ATTR(Attrs.DW_AT_upper_bound);
	ADD_ATTR(Attrs.DW_AT_use_location);
	ADD_ATTR(Attrs.DW_AT_use_UTF8);
	ADD_ATTR(Attrs.DW_AT_variable_parameter);
	ADD_ATTR(Attrs.DW_AT_virtuality);
	ADD_ATTR(Attrs.DW_AT_visibility);
	ADD_ATTR(Attrs.DW_AT_vtable_elem_location);
	ADD_ATTR(Attrs.DW_AT_type);

	// FIXME: Add the extended attributes.
	}

	// Add all of the attributes for \param Die to the hash.
	void DIEHash::addAttributes(DIE *Die) {
	DIEAttrs Attrs = {};
	collectAttributes(Die, Attrs);
	hashAttributes(Attrs, Die->getTag());
	}

	// Compute the hash of a DIE. This is based on the type signature computation
	// given in section 7.27 of the DWARF4 standard. It is the md5 hash of a
	// flattened description of the DIE.
	void DIEHash::computeHash(DIE *Die) {
	// Append the letter 'D', followed by the DWARF tag of the DIE.
	addULEB128('D');
	addULEB128(Die->getTag());

	// Add each of the attributes of the DIE.
	addAttributes(Die);

	// Then hash each of the children of the DIE.
	for (std::vector<DIE *>::const_iterator I = Die->getChildren().begin(),
	E = Die->getChildren().end();
	I != E; ++I)
	computeHash(*I);

	// Following the last (or if there are no children), append a zero byte.
	Hash.update(makeArrayRef((uint8_t)'\0'));
	}

	/// This is based on the type signature computation given in section 7.27 of the
	/// DWARF4 standard. It is the md5 hash of a flattened description of the DIE
	/// with the exception that we are hashing only the context and the name of the
	/// type.
	uint64_t DIEHash::computeDIEODRSignature(DIE *Die) {

	// Add the contexts to the hash. We won't be computing the ODR hash for
	// function local types so it's safe to use the generic context hashing
	// algorithm here.
	// FIXME: If we figure out how to account for linkage in some way we could
	// actually do this with a slight modification to the parent hash algorithm.
	DIE *Parent = Die->getParent();
	if (Parent)
	addParentContext(Parent);

	// Add the current DIE information.

	// Add the DWARF tag of the DIE.
	addULEB128(Die->getTag());

	// Add the name of the type to the hash.
	addString(getDIEStringAttr(Die, dwarf::DW_AT_name));

	// Now get the result.
	MD5::MD5Result Result;
	Hash.final(Result);

	// ... take the least significant 8 bytes and return those. Our MD5
	// implementation always returns its results in little endian, swap bytes
	// appropriately.
	return reinterpret_cast<support::ulittle64_t >(Result + 8);
	}

	/// This is based on the type signature computation given in section 7.27 of the
	/// DWARF4 standard. It is an md5 hash of the flattened description of the DIE
	/// with the inclusion of the full CU and all top level CU entities.
	// TODO: Initialize the type chain at 0 instead of 1 for CU signatures.
	uint64_t DIEHash::computeCUSignature(DIE *Die) {
	Numbering.clear();
	Numbering[Die] = 1;

	// Hash the DIE.
	computeHash(Die);

	// Now return the result.
	MD5::MD5Result Result;
	Hash.final(Result);

	// ... take the least significant 8 bytes and return those. Our MD5
	// implementation always returns its results in little endian, swap bytes
	// appropriately.
	return reinterpret_cast<support::ulittle64_t >(Result + 8);
	}

	/// This is based on the type signature computation given in section 7.27 of the
	/// DWARF4 standard. It is an md5 hash of the flattened description of the DIE
	/// with the inclusion of additional forms not specifically called out in the
	/// standard.
	uint64_t DIEHash::computeTypeSignature(DIE *Die) {
	Numbering.clear();
	Numbering[Die] = 1;

	if (DIE *Parent = Die->getParent())
	addParentContext(Parent);

	// Hash the DIE.
	computeHash(Die);

	// Now return the result.
	MD5::MD5Result Result;
	Hash.final(Result);

	// ... take the least significant 8 bytes and return those. Our MD5
	// implementation always returns its results in little endian, swap bytes
	// appropriately.
	return reinterpret_cast<support::ulittle64_t >(Result + 8);
	}