MFC 261991:

Upgrade our copy of llvm/clang to 3.4 release.  This version supports
all of the features in the current working draft of the upcoming C++
standard, provisionally named C++1y.

The code generator's performance is greatly increased, and the loop
auto-vectorizer is now enabled at -Os and -O2 in addition to -O3.  The
PowerPC backend has made several major improvements to code generation
quality and compile time, and the X86, SPARC, ARM32, Aarch64 and SystemZ
backends have all seen major feature work.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.4/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.4/tools/clang/docs/ReleaseNotes.html>

MFC 262121 (by emaste):

Update lldb for clang/llvm 3.4 import

This commit largely restores the lldb source to the upstream r196259
snapshot with the addition of threaded inferior support and a few bug
fixes.

Specific upstream lldb revisions restored include:
   SVN      git
  181387  779e6ac
  181703  7bef4e2
  182099  b31044e
  182650  f2dcf35
  182683  0d91b80
  183862  15c1774
  183929  99447a6
  184177  0b2934b
  184948  4dc3761
  184954  007e7bc
  186990  eebd175

Sponsored by:	DARPA, AFRL

MFC 262186 (by emaste):

Fix mismerge in r262121

A break statement was lost in the merge.  The error had no functional
impact, but restore it to reduce the diff against upstream.

MFC 262303:

Pull in r197521 from upstream clang trunk (by rdivacky):

  Use the integrated assembler by default on FreeBSD/ppc and ppc64.

Requested by:	jhibbits

MFC 262611:

Pull in r196874 from upstream llvm trunk:

  Fix a crash that occurs when PWD is invalid.

  MCJIT needs to be able to run in hostile environments, even when PWD
  is invalid. There's no need to crash MCJIT in this case.

  The obvious fix is to simply leave MCContext's CompilationDir empty
  when PWD can't be determined. This way, MCJIT clients,
  and other clients that link with LLVM don't need a valid working directory.

  If we do want to guarantee valid CompilationDir, that should be done
  only for clients of getCompilationDir(). This is as simple as checking
  for an empty string.

  The only current use of getCompilationDir is EmitGenDwarfInfo, which
  won't conceivably run with an invalid working dir. However, in the
  purely hypothetically and untestable case that this happens, the
  AT_comp_dir will be omitted from the compilation_unit DIE.

This should help fix assertions occurring with ports-mgmt/tinderbox,
when it is using jails, and sometimes invalidates clang's current
working directory.

Reported by:	decke

MFC 262809:

Pull in r203007 from upstream clang trunk:

  Don't produce an alias between destructors with different calling conventions.

  Fixes pr19007.

(Please note that is an LLVM PR identifier, not a FreeBSD one.)

This should fix Firefox and/or libxul crashes (due to problems with
regparm/stdcall calling conventions) on i386.

Reported by:	multiple users on freebsd-current
PR:		bin/187103

MFC 263048:

Repair recognition of "CC" as an alias for the C++ compiler, since it
was silently broken by upstream for a Windows-specific use-case.

Apparently some versions of CMake still rely on this archaic feature...

Reported by:	rakuco

MFC 263049:

Garbage collect the old way of adding the libstdc++ include directories
in clang's InitHeaderSearch.cpp.  This has been superseded by David
Chisnall's commit in r255321.

Moreover, if libc++ is used, the libstdc++ include directories should
not be in the search path at all.  These directories are now only used
if you pass -stdlib=libstdc++.

1 files changed, 507 insertions, 0 deletions

diff --git a/contrib/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp b/contrib/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
new file mode 100644
index 0000000..95eca90
--- /dev/null
+++ b/contrib/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
@@ -0,0 +1,507 @@
+//===-- 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 "DIEHash.h"
+
+#include "DIE.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(const 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(const 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<const DIE *, 1> Parents;
+  const DIE *Cur = &Parent;
+  while (Cur->getTag() != dwarf::DW_TAG_compile_unit) {
+    Parents.push_back(Cur);
+    Cur = Cur->getParent();
+  }
+
+  // Reverse iterate over our list to go from the outermost construct to the
+  // innermost.
+  for (SmallVectorImpl<const DIE *>::reverse_iterator I = Parents.rbegin(),
+                                                      E = Parents.rend();
+       I != E; ++I) {
+    const 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(const 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;
+    }
+  }
+}
+
+void DIEHash::hashShallowTypeReference(dwarf::Attribute Attribute,
+                                       const DIE &Entry, StringRef Name) {
+  // append the letter 'N'
+  addULEB128('N');
+
+  // the DWARF attribute code (DW_AT_type or DW_AT_friend),
+  addULEB128(Attribute);
+
+  // the context of the tag,
+  if (const DIE *Parent = Entry.getParent())
+    addParentContext(*Parent);
+
+  // the letter 'E',
+  addULEB128('E');
+
+  // and the name of the type.
+  addString(Name);
+
+  // Currently DW_TAG_friends are not used by Clang, but if they do become so,
+  // here's the relevant spec text to implement:
+  //
+  // 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).
+}
+
+void DIEHash::hashRepeatedTypeReference(dwarf::Attribute Attribute,
+                                        unsigned DieNumber) {
+  // a) If T is in the list of [previously hashed types], use the letter
+  // 'R' as the marker
+  addULEB128('R');
+
+  addULEB128(Attribute);
+
+  // and use the unsigned LEB128 encoding of [the index of T in the
+  // list] as the attribute value;
+  addULEB128(DieNumber);
+}
+
+void DIEHash::hashDIEEntry(dwarf::Attribute Attribute, dwarf::Tag Tag,
+                           const DIE &Entry) {
+  assert(Tag != dwarf::DW_TAG_friend && "No current LLVM clients emit friend "
+                                        "tags. Add support here when there's "
+                                        "a use case");
+  // Step 5
+  // If the tag in Step 3 is one of [the below tags]
+  if ((Tag == dwarf::DW_TAG_pointer_type ||
+       Tag == dwarf::DW_TAG_reference_type ||
+       Tag == dwarf::DW_TAG_rvalue_reference_type ||
+       Tag == dwarf::DW_TAG_ptr_to_member_type) &&
+      // and the referenced type (via the [below attributes])
+      // FIXME: This seems overly restrictive, and causes hash mismatches
+      // there's a decl/def difference in the containing type of a
+      // ptr_to_member_type, but it's what DWARF says, for some reason.
+      Attribute == dwarf::DW_AT_type) {
+    // ... has a DW_AT_name attribute,
+    StringRef Name = getDIEStringAttr(Entry, dwarf::DW_AT_name);
+    if (!Name.empty()) {
+      hashShallowTypeReference(Attribute, Entry, Name);
+      return;
+    }
+  }
+
+  unsigned &DieNumber = Numbering[&Entry];
+  if (DieNumber) {
+    hashRepeatedTypeReference(Attribute, DieNumber);
+    return;
+  }
+
+  // otherwise, b) use the letter 'T' as a the marker, ...
+  addULEB128('T');
+
+  addULEB128(Attribute);
+
+  // ... process the type T recursively by performing Steps 2 through 7, and
+  // use the result as the attribute value.
+  DieNumber = Numbering.size();
+  computeHash(Entry);
+}
+
+// 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;
+  dwarf::Attribute Attribute = Desc->getAttribute();
+
+  // 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)) {
+    hashDIEEntry(Attribute, Tag, *EntryAttr->getEntry());
+    return;
+  }
+
+  // Other attribute values use the letter 'A' as the marker, ...
+  addULEB128('A');
+
+  addULEB128(Attribute);
+
+  // ... 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(const DIE &Die) {
+  DIEAttrs Attrs = {};
+  collectAttributes(Die, Attrs);
+  hashAttributes(Attrs, Die.getTag());
+}
+
+void DIEHash::hashNestedType(const DIE &Die, StringRef Name) {
+  // 7.27 Step 7
+  // ... append the letter 'S',
+  addULEB128('S');
+
+  // the tag of C,
+  addULEB128(Die.getTag());
+
+  // and the name.
+  addString(Name);
+}
+
+// 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(const 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) {
+    // 7.27 Step 7
+    // If C is a nested type entry or a member function entry, ...
+    if (isType((*I)->getTag()) || (*I)->getTag() == dwarf::DW_TAG_subprogram) {
+      StringRef Name = getDIEStringAttr(**I, dwarf::DW_AT_name);
+      // ... and has a DW_AT_name attribute
+      if (!Name.empty()) {
+        hashNestedType(**I, Name);
+        continue;
+      }
+    }
+    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(const 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.
+  if (const DIE *Parent = Die.getParent())
+    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(const 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(const DIE &Die) {
+  Numbering.clear();
+  Numbering[&Die] = 1;
+
+  if (const 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);
+}