[MS Demangler] Fix several crashes and demangling bugs.

These bugs were found by writing a Python script which spidered
the entire Chromium build directory tree demangling every symbol
in every object file.  At the start, the tool printed:

  Processed 27443 object files.
  2926377/2936108 symbols successfully demangled (99.6686%)
  9731 symbols could not be demangled (0.3314%)
  14589 files crashed while demangling (53.1611%)

After this patch, it prints:

  Processed 27443 object files.
  41295518/41295617 symbols successfully demangled (99.9998%)
  99 symbols could not be demangled (0.0002%)
  0 files crashed while demangling (0.0000%)

The issues fixed in this patch are:

  * Ignore empty parameter packs.  Previously we would encounter
    a mangling for an empty parameter pack and add a null node
    to the AST.  Since we don't print these anyway, we now just
    don't add anything to the AST and ignore it entirely.  This
    fixes some of the crashes.

  * Account for "incorrect" string literal demanglings.  Apparently
    an older version of clang would not truncate mangled string
    literals to 32 bytes of encoded character data.  The demangling
    code however would allocate a 32 byte buffer thinking that it
    would not encounter more than this, and overrun the buffer.
    We now demangle up to 128 bytes of data, since the buggy
    clang would encode up to 32 *characters* of data.

  * Extended support for demangling init-fini stubs.  If you had
    something like
      struct Foo {
        static vector<string> S;
      };
    this would generate a dynamic atexit initializer *for the
    variable*.  We didn't handle this, but now we print something
    nice.  This is actually an improvement over undname, which will
    fail to demangle this at all.

  * Fixed one case of static this adjustment.  We weren't handling
    several thunk codes so we didn't recognize the mangling.  These
    are now handled.

  * Fixed a back-referencing problem.  Member pointer templates
    should have their components considered for back-referencing

The remaining 99 symbols which can't be demangled are all symbols
which are compiler-generated and undname can't demangle either.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341000 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Zachary Turner

lib/Demangle/MicrosoftDemangle.cpp

@@ -350,8 +350,8 @@ class Demangler {
   VariableSymbolNode *
   demangleRttiBaseClassDescriptorNode(ArenaAllocator &Arena,
                                       StringView &MangledName);
-  FunctionSymbolNode *demangleDynamicStructorFunction(StringView &MangledName,
-                                                      bool IsDestructor);
+  FunctionSymbolNode *demangleInitFiniStub(StringView &MangledName,
+                                           bool IsDestructor);
 
   NamedIdentifierNode *demangleSimpleName(StringView &MangledName,
                                           bool Memorize);
@@ -520,16 +520,35 @@ Demangler::demangleRttiBaseClassDescriptorNode(ArenaAllocator &Arena,
   return VSN;
 }
 
-FunctionSymbolNode *
-Demangler::demangleDynamicStructorFunction(StringView &MangledName,
-                                           bool IsDestructor) {
+FunctionSymbolNode *Demangler::demangleInitFiniStub(StringView &MangledName,
+                                                    bool IsDestructor) {
   DynamicStructorIdentifierNode *DSIN =
       Arena.alloc<DynamicStructorIdentifierNode>();
   DSIN->IsDestructor = IsDestructor;
-  DSIN->Name = demangleFullyQualifiedTypeName(MangledName);
-  QualifiedNameNode *QNN = synthesizeQualifiedName(Arena, DSIN);
-  FunctionSymbolNode *FSN = demangleFunctionEncoding(MangledName);
-  FSN->Name = QNN;
+
+  // What follows is a main symbol name. This may include namespaces or class
+  // back references.
+  QualifiedNameNode *QN = demangleFullyQualifiedSymbolName(MangledName);
+
+  SymbolNode *Symbol = demangleEncodedSymbol(MangledName, QN);
+  FunctionSymbolNode *FSN = nullptr;
+  Symbol->Name = QN;
+
+  if (Symbol->kind() == NodeKind::VariableSymbol) {
+    DSIN->Variable = static_cast<VariableSymbolNode *>(Symbol);
+    if (!MangledName.consumeFront('@')) {
+      Error = true;
+      return nullptr;
+    }
+
+    FSN = demangleFunctionEncoding(MangledName);
+    FSN->Name = synthesizeQualifiedName(Arena, DSIN);
+  } else {
+    FSN = static_cast<FunctionSymbolNode *>(Symbol);
+    DSIN->Name = Symbol->Name;
+    FSN->Name = synthesizeQualifiedName(Arena, DSIN);
+  }
+
   return FSN;
 }
 
@@ -569,9 +588,9 @@ SymbolNode *Demangler::demangleSpecialIntrinsic(StringView &MangledName) {
   case SpecialIntrinsicKind::RttiBaseClassDescriptor:
     return demangleRttiBaseClassDescriptorNode(Arena, MangledName);
   case SpecialIntrinsicKind::DynamicInitializer:
-    return demangleDynamicStructorFunction(MangledName, false);
+    return demangleInitFiniStub(MangledName, false);
   case SpecialIntrinsicKind::DynamicAtexitDestructor:
-    return demangleDynamicStructorFunction(MangledName, true);
+    return demangleInitFiniStub(MangledName, true);
   default:
     break;
   }
@@ -837,6 +856,8 @@ SymbolNode *Demangler::parse(StringView &MangledName) {
   // What follows is a main symbol name. This may include namespaces or class
   // back references.
   QualifiedNameNode *QN = demangleFullyQualifiedSymbolName(MangledName);
+  if (Error)
+    return nullptr;
 
   SymbolNode *Symbol = demangleEncodedSymbol(MangledName, QN);
   if (Symbol) {
@@ -1325,10 +1346,9 @@ Demangler::demangleStringLiteral(StringView &MangledName) {
         goto StringLiteralError;
     }
   } else {
-    if (StringByteSize > 32)
-      Result->IsTruncated = true;
-
-    constexpr unsigned MaxStringByteLength = 32;
+    // The max byte length is actually 32, but some compilers mangled strings
+    // incorrectly, so we have to assume it can go higher.
+    constexpr unsigned MaxStringByteLength = 32 * 4;
     uint8_t StringBytes[MaxStringByteLength];
 
     unsigned BytesDecoded = 0;
@@ -1337,6 +1357,9 @@ Demangler::demangleStringLiteral(StringView &MangledName) {
       StringBytes[BytesDecoded++] = demangleCharLiteral(MangledName);
     }
 
+    if (StringByteSize > BytesDecoded)
+      Result->IsTruncated = true;
+
     unsigned CharBytes =
         guessCharByteSize(StringBytes, BytesDecoded, StringByteSize);
     assert(StringByteSize % CharBytes == 0);
@@ -1587,6 +1610,10 @@ FuncClass Demangler::demangleFunctionClass(StringView &MangledName) {
     return FuncClass(FC_Private | FC_Virtual);
   case 'F':
     return FuncClass(FC_Private | FC_Virtual);
+  case 'G':
+    return FuncClass(FC_Private | FC_StaticThisAdjust);
+  case 'H':
+    return FuncClass(FC_Private | FC_StaticThisAdjust | FC_Far);
   case 'I':
     return FuncClass(FC_Protected);
   case 'J':
@@ -1760,7 +1787,6 @@ TypeNode *Demangler::demangleType(StringView &MangledName,
     Ty = demangleCustomType(MangledName);
   } else {
     Ty = demanglePrimitiveType(MangledName);
-    assert(Ty && !Error);
     if (!Ty || Error)
       return Ty;
   }
@@ -1976,14 +2002,14 @@ PointerTypeNode *Demangler::demangleMemberPointerType(StringView &MangledName) {
   Pointer->Quals = Qualifiers(Pointer->Quals | ExtQuals);
 
   if (MangledName.consumeFront("8")) {
-    Pointer->ClassParent = demangleFullyQualifiedSymbolName(MangledName);
+    Pointer->ClassParent = demangleFullyQualifiedTypeName(MangledName);
     Pointer->Pointee = demangleFunctionType(MangledName, true);
   } else {
     Qualifiers PointeeQuals = Q_None;
     bool IsMember = false;
     std::tie(PointeeQuals, IsMember) = demangleQualifiers(MangledName);
     assert(IsMember);
-    Pointer->ClassParent = demangleFullyQualifiedSymbolName(MangledName);
+    Pointer->ClassParent = demangleFullyQualifiedTypeName(MangledName);
 
     Pointer->Pointee = demangleType(MangledName, QualifierMangleMode::Drop);
     Pointer->Pointee->Quals = PointeeQuals;
@@ -2121,18 +2147,21 @@ Demangler::demangleTemplateParameterList(StringView &MangledName) {
   size_t Count = 0;
 
   while (!Error && !MangledName.startsWith('@')) {
+    if (MangledName.consumeFront("$S") || MangledName.consumeFront("$$V") ||
+        MangledName.consumeFront("$$$V")) {
+      // Empty parameter pack.
+      continue;
+    }
+
     ++Count;
+
     // Template parameter lists don't participate in back-referencing.
     *Current = Arena.alloc<NodeList>();
 
     NodeList &TP = **Current;
 
     TemplateParameterReferenceNode *TPRN = nullptr;
-    if (MangledName.consumeFront("$S") || MangledName.consumeFront("$$V") ||
-        MangledName.consumeFront("$$$V")) {
-      // Empty parameter pack.
-      TP.N = nullptr;
-    } else if (MangledName.consumeFront("$$Y")) {
+    if (MangledName.consumeFront("$$Y")) {
       // Template alias
       TP.N = demangleFullyQualifiedTypeName(MangledName);
     } else if (MangledName.consumeFront("$$B")) {

lib/Demangle/MicrosoftDemangleNodes.cpp

@@ -223,9 +223,15 @@ void DynamicStructorIdentifierNode::output(OutputStream &OS,
   else
     OS << "`dynamic initializer for ";
 
-  OS << "'";
-  Name->output(OS, Flags);
-  OS << "''";
+  if (Variable) {
+    OS << "`";
+    Variable->output(OS, Flags);
+    OS << "''";
+  } else {
+    OS << "'";
+    Name->output(OS, Flags);
+    OS << "''";
+  }
 }
 
 void NamedIdentifierNode::output(OutputStream &OS, OutputFlags Flags) const {

lib/Demangle/MicrosoftDemangleNodes.h

@@ -322,7 +322,7 @@ enum class NodeKind {
   LocalStaticGuardVariable,
   FunctionSymbol,
   VariableSymbol,
-  SpecialTableSymbol,
+  SpecialTableSymbol
 };
 
 struct Node {
@@ -443,6 +443,7 @@ struct DynamicStructorIdentifierNode : public IdentifierNode {
 
   void output(OutputStream &OS, OutputFlags Flags) const override;
 
+  VariableSymbolNode *Variable = nullptr;
   QualifiedNameNode *Name = nullptr;
   bool IsDestructor = false;
 };

test/Demangle/ms-back-references.test

@@ -169,3 +169,6 @@
 
 ?AddEmitPasses@EmitAssemblyHelper@?A0x43583946@@AEAA_NAEAVPassManager@legacy@llvm@@W4BackendAction@clang@@AEAVraw_pwrite_stream@5@PEAV85@@Z
 ; CHECK: bool __cdecl `anonymous namespace'::EmitAssemblyHelper::AddEmitPasses(class llvm::legacy::PassManager &, enum clang::BackendAction, class llvm::raw_pwrite_stream &, class llvm::raw_pwrite_stream *)
+
+??$forward@P8?$DecoderStream@$01@media@@AEXXZ@std@@YA$$QAP8?$DecoderStream@$01@media@@AEXXZAAP812@AEXXZ@Z
+; CHECK: void (__thiscall media::DecoderStream<2>::*&& __cdecl std::forward<void (__thiscall media::DecoderStream<2>::*)(void)>(void (__thiscall media::DecoderStream<2>::*&)(void)))(void)

test/Demangle/ms-operators.test

@@ -161,6 +161,9 @@
 ??_EBase@@UEAAPEAXI@Z
 ; CHECK: virtual void * __cdecl Base::`vector deleting dtor'(unsigned int)
 
+??_EBase@@G3AEPAXI@Z
+; CHECK: [thunk]: void * __thiscall Base::`vector deleting dtor'`adjustor{4}'(unsigned int)
+
 ??_F?$SomeTemplate@H@@QAEXXZ
 ; CHECK: void __thiscall SomeTemplate<int>::`default ctor closure'(void)
 
@@ -224,6 +227,9 @@
 ??__FFoo@@YAXXZ
 ; CHECK: void __cdecl `dynamic atexit destructor for 'Foo''(void)
 
+??__F_decisionToDFA@XPathLexer@@0V?$vector@VDFA@dfa@antlr4@@V?$allocator@VDFA@dfa@antlr4@@@std@@@std@@A@YAXXZ
+; CHECK: void __cdecl `dynamic atexit destructor for `static class std::vector<class antlr4::dfa::DFA, class std::allocator<class antlr4::dfa::DFA>> XPathLexer::_decisionToDFA''(void)
+
 ??__K_deg@@YAHO@Z
 ; CHECK: int __cdecl operator ""_deg(long double)
 

test/Demangle/ms-string-literals.test

@@ -761,4 +761,13 @@
 ; CHECK: const char16_t * {u"012345678901234"}
 
 ??_C@_0CA@KFPHPCC@0?$AA?$AA?$AA1?$AA?$AA?$AA2?$AA?$AA?$AA3?$AA?$AA?$AA4?$AA?$AA?$AA5?$AA?$AA?$AA6?$AA?$AA?$AA?$AA?$AA?$AA?$AA@
-; CHECK: const char32_t * {U"0123456"}
+; CHECK: const char32_t * {U"0123456"}
+
+; There are too many bytes encoded in this string literal (it should encode a max of 32 bytes)
+; but some buggy compilers will incorrectly generate this, so we need to be able to demangle
+; both the correct and incorrect versions.
+??_C@_0CG@HJGBPLNO@l?$AAo?$AAo?$AAk?$AAA?$AAh?$AAe?$AAa?$AAd?$AAH?$AAa?$AAr?$AAd?$AAB?$AAr?$AAe?$AAa?$AAk?$AA?$AA?$AA@
+; CHECK: const char16_t * {u"lookAheadHardBreak"}
+
+??_C@_0CG@HJGBPLNO@l?$AAo?$AAo?$AAk?$AAA?$AAh?$AAe?$AAa?$AAd?$AAH?$AAa?$AAr?$AAd?$AAB?$AAr?$AAe?$AA@
+; CHECK: const char16_t * {u"lookAheadHardBre"...}