[Debuginfo][COFF] Minimal serialization support for precompiled types records

This change adds support for the LF_PRECOMP and LF_ENDPRECOMP records required
to read/write Microsoft precompiled types .objs.
See https://en.wikipedia.org/wiki/Precompiled_header#Microsoft_Visual_C_and_C++

This also adds handling for the .debug$P section, which is actually a .debug$T
section in disguise, found only in precompiled .objs.

Differential Revision: https://reviews.llvm.org/D45283

llvm-svn: 329613

1 files changed, 333 insertions, 323 deletions

diff --git a/llvm/lib/DebugInfo/CodeView/RecordName.cpp b/llvm/lib/DebugInfo/CodeView/RecordName.cpp
index e6fd7cd3d28..d18d346e86a 100644
--- a/llvm/lib/DebugInfo/CodeView/RecordName.cpp
+++ b/llvm/lib/DebugInfo/CodeView/RecordName.cpp
@@ -1,323 +1,333 @@
-//===- RecordName.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/DebugInfo/CodeView/RecordName.h"
-
-#include "llvm/ADT/SmallString.h"
-#include "llvm/DebugInfo/CodeView/CVSymbolVisitor.h"
-#include "llvm/DebugInfo/CodeView/CVTypeVisitor.h"
-#include "llvm/DebugInfo/CodeView/SymbolRecordMapping.h"
-#include "llvm/DebugInfo/CodeView/TypeVisitorCallbacks.h"
-#include "llvm/Support/FormatVariadic.h"
-
-using namespace llvm;
-using namespace llvm::codeview;
-
-namespace {
-class TypeNameComputer : public TypeVisitorCallbacks {
-  /// The type collection.  Used to calculate names of nested types.
-  TypeCollection &Types;
-  TypeIndex CurrentTypeIndex = TypeIndex::None();
-
-  /// Name of the current type. Only valid before visitTypeEnd.
-  SmallString<256> Name;
-
-public:
-  explicit TypeNameComputer(TypeCollection &Types) : Types(Types) {}
-
-  StringRef name() const { return Name; }
-
-  /// Paired begin/end actions for all types. Receives all record data,
-  /// including the fixed-length record prefix.
-  Error visitTypeBegin(CVType &Record) override;
-  Error visitTypeBegin(CVType &Record, TypeIndex Index) override;
-  Error visitTypeEnd(CVType &Record) override;
-
-#define TYPE_RECORD(EnumName, EnumVal, Name)                                   \
-  Error visitKnownRecord(CVType &CVR, Name##Record &Record) override;
-#define TYPE_RECORD_ALIAS(EnumName, EnumVal, Name, AliasName)
-#define MEMBER_RECORD(EnumName, EnumVal, Name)
-#include "llvm/DebugInfo/CodeView/CodeViewTypes.def"
-};
-} // namespace
-
-Error TypeNameComputer::visitTypeBegin(CVType &Record) {
-  llvm_unreachable("Must call visitTypeBegin with a TypeIndex!");
-  return Error::success();
-}
-
-Error TypeNameComputer::visitTypeBegin(CVType &Record, TypeIndex Index) {
-  // Reset Name to the empty string. If the visitor sets it, we know it.
-  Name = "";
-  CurrentTypeIndex = Index;
-  return Error::success();
-}
-
-Error TypeNameComputer::visitTypeEnd(CVType &CVR) { return Error::success(); }
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR,
-                                         FieldListRecord &FieldList) {
-  Name = "<field list>";
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVRecord<TypeLeafKind> &CVR,
-                                         StringIdRecord &String) {
-  Name = String.getString();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, ArgListRecord &Args) {
-  auto Indices = Args.getIndices();
-  uint32_t Size = Indices.size();
-  Name = "(";
-  for (uint32_t I = 0; I < Size; ++I) {
-    assert(Indices[I] < CurrentTypeIndex);
-
-    Name.append(Types.getTypeName(Indices[I]));
-    if (I + 1 != Size)
-      Name.append(", ");
-  }
-  Name.push_back(')');
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR,
-                                         StringListRecord &Strings) {
-  auto Indices = Strings.getIndices();
-  uint32_t Size = Indices.size();
-  Name = "\"";
-  for (uint32_t I = 0; I < Size; ++I) {
-    Name.append(Types.getTypeName(Indices[I]));
-    if (I + 1 != Size)
-      Name.append("\" \"");
-  }
-  Name.push_back('\"');
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, ClassRecord &Class) {
-  Name = Class.getName();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, UnionRecord &Union) {
-  Name = Union.getName();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, EnumRecord &Enum) {
-  Name = Enum.getName();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, ArrayRecord &AT) {
-  Name = AT.getName();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, VFTableRecord &VFT) {
-  Name = VFT.getName();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, MemberFuncIdRecord &Id) {
-  Name = Id.getName();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, ProcedureRecord &Proc) {
-  StringRef Ret = Types.getTypeName(Proc.getReturnType());
-  StringRef Params = Types.getTypeName(Proc.getArgumentList());
-  Name = formatv("{0} {1}", Ret, Params).sstr<256>();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR,
-                                         MemberFunctionRecord &MF) {
-  StringRef Ret = Types.getTypeName(MF.getReturnType());
-  StringRef Class = Types.getTypeName(MF.getClassType());
-  StringRef Params = Types.getTypeName(MF.getArgumentList());
-  Name = formatv("{0} {1}::{2}", Ret, Class, Params).sstr<256>();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, FuncIdRecord &Func) {
-  Name = Func.getName();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, TypeServer2Record &TS) {
-  Name = TS.getName();
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, PointerRecord &Ptr) {
-
-  if (Ptr.isPointerToMember()) {
-    const MemberPointerInfo &MI = Ptr.getMemberInfo();
-
-    StringRef Pointee = Types.getTypeName(Ptr.getReferentType());
-    StringRef Class = Types.getTypeName(MI.getContainingType());
-    Name = formatv("{0} {1}::*", Pointee, Class);
-  } else {
-    Name.append(Types.getTypeName(Ptr.getReferentType()));
-
-    if (Ptr.getMode() == PointerMode::LValueReference)
-      Name.append("&");
-    else if (Ptr.getMode() == PointerMode::RValueReference)
-      Name.append("&&");
-    else if (Ptr.getMode() == PointerMode::Pointer)
-      Name.append("*");
-
-    // Qualifiers in pointer records apply to the pointer, not the pointee, so
-    // they go on the right.
-    if (Ptr.isConst())
-      Name.append(" const");
-    if (Ptr.isVolatile())
-      Name.append(" volatile");
-    if (Ptr.isUnaligned())
-      Name.append(" __unaligned");
-    if (Ptr.isRestrict())
-      Name.append(" __restrict");
-  }
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, ModifierRecord &Mod) {
-  uint16_t Mods = static_cast<uint16_t>(Mod.getModifiers());
-
-  if (Mods & uint16_t(ModifierOptions::Const))
-    Name.append("const ");
-  if (Mods & uint16_t(ModifierOptions::Volatile))
-    Name.append("volatile ");
-  if (Mods & uint16_t(ModifierOptions::Unaligned))
-    Name.append("__unaligned ");
-  Name.append(Types.getTypeName(Mod.getModifiedType()));
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR,
-                                         VFTableShapeRecord &Shape) {
-  Name = formatv("<vftable {0} methods>", Shape.getEntryCount());
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(
-    CVType &CVR, UdtModSourceLineRecord &ModSourceLine) {
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR,
-                                         UdtSourceLineRecord &SourceLine) {
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, BitFieldRecord &BF) {
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR,
-                                         MethodOverloadListRecord &Overloads) {
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, BuildInfoRecord &BI) {
-  return Error::success();
-}
-
-Error TypeNameComputer::visitKnownRecord(CVType &CVR, LabelRecord &R) {
-  return Error::success();
-}
-
-std::string llvm::codeview::computeTypeName(TypeCollection &Types,
-                                            TypeIndex Index) {
-  TypeNameComputer Computer(Types);
-  CVType Record = Types.getType(Index);
-  if (auto EC = visitTypeRecord(Record, Index, Computer)) {
-    consumeError(std::move(EC));
-    return "<unknown UDT>";
-  }
-  return Computer.name();
-}
-
-static int getSymbolNameOffset(CVSymbol Sym) {
-  switch (Sym.kind()) {
-  // See ProcSym
-  case SymbolKind::S_GPROC32:
-  case SymbolKind::S_LPROC32:
-  case SymbolKind::S_GPROC32_ID:
-  case SymbolKind::S_LPROC32_ID:
-  case SymbolKind::S_LPROC32_DPC:
-  case SymbolKind::S_LPROC32_DPC_ID:
-    return 35;
-  // See Thunk32Sym
-  case SymbolKind::S_THUNK32:
-    return 21;
-  // See SectionSym
-  case SymbolKind::S_SECTION:
-    return 16;
-  // See CoffGroupSym
-  case SymbolKind::S_COFFGROUP:
-    return 14;
-  // See PublicSym32, FileStaticSym, RegRelativeSym, DataSym, ThreadLocalDataSym
-  case SymbolKind::S_PUB32:
-  case SymbolKind::S_FILESTATIC:
-  case SymbolKind::S_REGREL32:
-  case SymbolKind::S_GDATA32:
-  case SymbolKind::S_LDATA32:
-  case SymbolKind::S_LMANDATA:
-  case SymbolKind::S_GMANDATA:
-  case SymbolKind::S_LTHREAD32:
-  case SymbolKind::S_GTHREAD32:
-    return 10;
-  // See RegisterSym and LocalSym
-  case SymbolKind::S_REGISTER:
-  case SymbolKind::S_LOCAL:
-    return 6;
-  // See BlockSym
-  case SymbolKind::S_BLOCK32:
-    return 18;
-  // See LabelSym
-  case SymbolKind::S_LABEL32:
-    return 7;
-  // See ObjNameSym, ExportSym, and UDTSym
-  case SymbolKind::S_OBJNAME:
-  case SymbolKind::S_EXPORT:
-  case SymbolKind::S_UDT:
-    return 4;
-  // See BPRelativeSym
-  case SymbolKind::S_BPREL32:
-    return 8;
-  default:
-    return -1;
-  }
-}
-
-StringRef llvm::codeview::getSymbolName(CVSymbol Sym) {
-  if (Sym.kind() == SymbolKind::S_CONSTANT) {
-    // S_CONSTANT is preceded by an APSInt, which has a variable length.  So we
-    // have to do a full deserialization.
-    BinaryStreamReader Reader(Sym.content(), llvm::support::little);
-    // The container doesn't matter for single records.
-    SymbolRecordMapping Mapping(Reader, CodeViewContainer::ObjectFile);
-    ConstantSym Const(SymbolKind::S_CONSTANT);
-    cantFail(Mapping.visitSymbolBegin(Sym));
-    cantFail(Mapping.visitKnownRecord(Sym, Const));
-    cantFail(Mapping.visitSymbolEnd(Sym));
-    return Const.Name;
-  }
-
-  int Offset = getSymbolNameOffset(Sym);
-  if (Offset == -1)
-    return StringRef();
-
-  StringRef StringData = toStringRef(Sym.content()).drop_front(Offset);
-  return StringData.split('\0').first;
-}
+//===- RecordName.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/DebugInfo/CodeView/RecordName.h"

+

+#include "llvm/ADT/SmallString.h"

+#include "llvm/DebugInfo/CodeView/CVSymbolVisitor.h"

+#include "llvm/DebugInfo/CodeView/CVTypeVisitor.h"

+#include "llvm/DebugInfo/CodeView/SymbolRecordMapping.h"

+#include "llvm/DebugInfo/CodeView/TypeVisitorCallbacks.h"

+#include "llvm/Support/FormatVariadic.h"

+

+using namespace llvm;

+using namespace llvm::codeview;

+

+namespace {

+class TypeNameComputer : public TypeVisitorCallbacks {

+  /// The type collection.  Used to calculate names of nested types.

+  TypeCollection &Types;

+  TypeIndex CurrentTypeIndex = TypeIndex::None();

+

+  /// Name of the current type. Only valid before visitTypeEnd.

+  SmallString<256> Name;

+

+public:

+  explicit TypeNameComputer(TypeCollection &Types) : Types(Types) {}

+

+  StringRef name() const { return Name; }

+

+  /// Paired begin/end actions for all types. Receives all record data,

+  /// including the fixed-length record prefix.

+  Error visitTypeBegin(CVType &Record) override;

+  Error visitTypeBegin(CVType &Record, TypeIndex Index) override;

+  Error visitTypeEnd(CVType &Record) override;

+

+#define TYPE_RECORD(EnumName, EnumVal, Name)                                   \

+  Error visitKnownRecord(CVType &CVR, Name##Record &Record) override;

+#define TYPE_RECORD_ALIAS(EnumName, EnumVal, Name, AliasName)

+#define MEMBER_RECORD(EnumName, EnumVal, Name)

+#include "llvm/DebugInfo/CodeView/CodeViewTypes.def"

+};

+} // namespace

+

+Error TypeNameComputer::visitTypeBegin(CVType &Record) {

+  llvm_unreachable("Must call visitTypeBegin with a TypeIndex!");

+  return Error::success();

+}

+

+Error TypeNameComputer::visitTypeBegin(CVType &Record, TypeIndex Index) {

+  // Reset Name to the empty string. If the visitor sets it, we know it.

+  Name = "";

+  CurrentTypeIndex = Index;

+  return Error::success();

+}

+

+Error TypeNameComputer::visitTypeEnd(CVType &CVR) { return Error::success(); }

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR,

+                                         FieldListRecord &FieldList) {

+  Name = "<field list>";

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVRecord<TypeLeafKind> &CVR,

+                                         StringIdRecord &String) {

+  Name = String.getString();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, ArgListRecord &Args) {

+  auto Indices = Args.getIndices();

+  uint32_t Size = Indices.size();

+  Name = "(";

+  for (uint32_t I = 0; I < Size; ++I) {

+    assert(Indices[I] < CurrentTypeIndex);

+

+    Name.append(Types.getTypeName(Indices[I]));

+    if (I + 1 != Size)

+      Name.append(", ");

+  }

+  Name.push_back(')');

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR,

+                                         StringListRecord &Strings) {

+  auto Indices = Strings.getIndices();

+  uint32_t Size = Indices.size();

+  Name = "\"";

+  for (uint32_t I = 0; I < Size; ++I) {

+    Name.append(Types.getTypeName(Indices[I]));

+    if (I + 1 != Size)

+      Name.append("\" \"");

+  }

+  Name.push_back('\"');

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, ClassRecord &Class) {

+  Name = Class.getName();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, UnionRecord &Union) {

+  Name = Union.getName();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, EnumRecord &Enum) {

+  Name = Enum.getName();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, ArrayRecord &AT) {

+  Name = AT.getName();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, VFTableRecord &VFT) {

+  Name = VFT.getName();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, MemberFuncIdRecord &Id) {

+  Name = Id.getName();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, ProcedureRecord &Proc) {

+  StringRef Ret = Types.getTypeName(Proc.getReturnType());

+  StringRef Params = Types.getTypeName(Proc.getArgumentList());

+  Name = formatv("{0} {1}", Ret, Params).sstr<256>();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR,

+                                         MemberFunctionRecord &MF) {

+  StringRef Ret = Types.getTypeName(MF.getReturnType());

+  StringRef Class = Types.getTypeName(MF.getClassType());

+  StringRef Params = Types.getTypeName(MF.getArgumentList());

+  Name = formatv("{0} {1}::{2}", Ret, Class, Params).sstr<256>();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, FuncIdRecord &Func) {

+  Name = Func.getName();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, TypeServer2Record &TS) {

+  Name = TS.getName();

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, PointerRecord &Ptr) {

+

+  if (Ptr.isPointerToMember()) {

+    const MemberPointerInfo &MI = Ptr.getMemberInfo();

+

+    StringRef Pointee = Types.getTypeName(Ptr.getReferentType());

+    StringRef Class = Types.getTypeName(MI.getContainingType());

+    Name = formatv("{0} {1}::*", Pointee, Class);

+  } else {

+    Name.append(Types.getTypeName(Ptr.getReferentType()));

+

+    if (Ptr.getMode() == PointerMode::LValueReference)

+      Name.append("&");

+    else if (Ptr.getMode() == PointerMode::RValueReference)

+      Name.append("&&");

+    else if (Ptr.getMode() == PointerMode::Pointer)

+      Name.append("*");

+

+    // Qualifiers in pointer records apply to the pointer, not the pointee, so

+    // they go on the right.

+    if (Ptr.isConst())

+      Name.append(" const");

+    if (Ptr.isVolatile())

+      Name.append(" volatile");

+    if (Ptr.isUnaligned())

+      Name.append(" __unaligned");

+    if (Ptr.isRestrict())

+      Name.append(" __restrict");

+  }

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, ModifierRecord &Mod) {

+  uint16_t Mods = static_cast<uint16_t>(Mod.getModifiers());

+

+  if (Mods & uint16_t(ModifierOptions::Const))

+    Name.append("const ");

+  if (Mods & uint16_t(ModifierOptions::Volatile))

+    Name.append("volatile ");

+  if (Mods & uint16_t(ModifierOptions::Unaligned))

+    Name.append("__unaligned ");

+  Name.append(Types.getTypeName(Mod.getModifiedType()));

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR,

+                                         VFTableShapeRecord &Shape) {

+  Name = formatv("<vftable {0} methods>", Shape.getEntryCount());

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(

+    CVType &CVR, UdtModSourceLineRecord &ModSourceLine) {

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR,

+                                         UdtSourceLineRecord &SourceLine) {

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, BitFieldRecord &BF) {

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR,

+                                         MethodOverloadListRecord &Overloads) {

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, BuildInfoRecord &BI) {

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR, LabelRecord &R) {

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR,

+                                         PrecompRecord &Precomp) {

+  return Error::success();

+}

+

+Error TypeNameComputer::visitKnownRecord(CVType &CVR,

+                                         EndPrecompRecord &EndPrecomp) {

+  return Error::success();

+}

+

+std::string llvm::codeview::computeTypeName(TypeCollection &Types,

+                                            TypeIndex Index) {

+  TypeNameComputer Computer(Types);

+  CVType Record = Types.getType(Index);

+  if (auto EC = visitTypeRecord(Record, Index, Computer)) {

+    consumeError(std::move(EC));

+    return "<unknown UDT>";

+  }

+  return Computer.name();

+}

+

+static int getSymbolNameOffset(CVSymbol Sym) {

+  switch (Sym.kind()) {

+  // See ProcSym

+  case SymbolKind::S_GPROC32:

+  case SymbolKind::S_LPROC32:

+  case SymbolKind::S_GPROC32_ID:

+  case SymbolKind::S_LPROC32_ID:

+  case SymbolKind::S_LPROC32_DPC:

+  case SymbolKind::S_LPROC32_DPC_ID:

+    return 35;

+  // See Thunk32Sym

+  case SymbolKind::S_THUNK32:

+    return 21;

+  // See SectionSym

+  case SymbolKind::S_SECTION:

+    return 16;

+  // See CoffGroupSym

+  case SymbolKind::S_COFFGROUP:

+    return 14;

+  // See PublicSym32, FileStaticSym, RegRelativeSym, DataSym, ThreadLocalDataSym

+  case SymbolKind::S_PUB32:

+  case SymbolKind::S_FILESTATIC:

+  case SymbolKind::S_REGREL32:

+  case SymbolKind::S_GDATA32:

+  case SymbolKind::S_LDATA32:

+  case SymbolKind::S_LMANDATA:

+  case SymbolKind::S_GMANDATA:

+  case SymbolKind::S_LTHREAD32:

+  case SymbolKind::S_GTHREAD32:

+    return 10;

+  // See RegisterSym and LocalSym

+  case SymbolKind::S_REGISTER:

+  case SymbolKind::S_LOCAL:

+    return 6;

+  // See BlockSym

+  case SymbolKind::S_BLOCK32:

+    return 18;

+  // See LabelSym

+  case SymbolKind::S_LABEL32:

+    return 7;

+  // See ObjNameSym, ExportSym, and UDTSym

+  case SymbolKind::S_OBJNAME:

+  case SymbolKind::S_EXPORT:

+  case SymbolKind::S_UDT:

+    return 4;

+  // See BPRelativeSym

+  case SymbolKind::S_BPREL32:

+    return 8;

+  default:

+    return -1;

+  }

+}

+

+StringRef llvm::codeview::getSymbolName(CVSymbol Sym) {

+  if (Sym.kind() == SymbolKind::S_CONSTANT) {

+    // S_CONSTANT is preceded by an APSInt, which has a variable length.  So we

+    // have to do a full deserialization.

+    BinaryStreamReader Reader(Sym.content(), llvm::support::little);

+    // The container doesn't matter for single records.

+    SymbolRecordMapping Mapping(Reader, CodeViewContainer::ObjectFile);

+    ConstantSym Const(SymbolKind::S_CONSTANT);

+    cantFail(Mapping.visitSymbolBegin(Sym));

+    cantFail(Mapping.visitKnownRecord(Sym, Const));

+    cantFail(Mapping.visitSymbolEnd(Sym));

+    return Const.Name;

+  }

+

+  int Offset = getSymbolNameOffset(Sym);

+  if (Offset == -1)

+    return StringRef();

+

+  StringRef StringData = toStringRef(Sym.content()).drop_front(Offset);

+  return StringData.split('\0').first;

+}