[LLDB] Fix handling for the clang name mangling extension for block invocations

Add support for clangs  mangling extension for block invocations.

Differential Revision: https://reviews.llvm.org/D69738

lldb/include/lldb/Core/Mangled.h

@@ -261,6 +261,15 @@ public:
   bool DemangleWithRichManglingInfo(RichManglingContext &context,
                                     SkipMangledNameFn *skip_mangled_name);
 
+  /// Try to identify the mangling scheme used.
+  /// \param[in] name
+  ///     The name we are attempting to identify the mangling scheme for.
+  ///
+  /// \return
+  ///     eManglingSchemeNone if no known mangling scheme could be identified
+  ///     for s, otherwise the enumerator for the mangling scheme detected.
+  static Mangled::ManglingScheme GetManglingScheme(llvm::StringRef const name);
+
 private:
   /// Mangled member variables.
   ConstString m_mangled;           ///< The mangled version of the name

lldb/source/Core/Mangled.cpp

@@ -32,18 +32,8 @@
 #include <string.h>
 using namespace lldb_private;
 
-static inline Mangled::ManglingScheme cstring_mangling_scheme(const char *s) {
-  if (s) {
-    if (s[0] == '?')
-      return Mangled::eManglingSchemeMSVC;
-    if (s[0] == '_' && s[1] == 'Z')
-      return Mangled::eManglingSchemeItanium;
-  }
-  return Mangled::eManglingSchemeNone;
-}
-
-static inline bool cstring_is_mangled(const char *s) {
-  return cstring_mangling_scheme(s) != Mangled::eManglingSchemeNone;
+static inline bool cstring_is_mangled(llvm::StringRef s) {
+  return Mangled::GetManglingScheme(s) != Mangled::eManglingSchemeNone;
 }
 
 static ConstString 
@@ -99,6 +89,23 @@ get_demangled_name_without_arguments(ConstString mangled,
 
 #pragma mark Mangled
 
+Mangled::ManglingScheme Mangled::GetManglingScheme(llvm::StringRef const name) {
+  if (name.empty())
+    return Mangled::eManglingSchemeNone;
+
+  if (name.startswith("?"))
+    return Mangled::eManglingSchemeMSVC;
+
+  if (name.startswith("_Z"))
+    return Mangled::eManglingSchemeItanium;
+
+  // ___Z is a clang extension of block invocations
+  if (name.startswith("___Z"))
+    return Mangled::eManglingSchemeItanium;
+
+  return Mangled::eManglingSchemeNone;
+}
+
 Mangled::Mangled(ConstString s) : m_mangled(), m_demangled() {
   if (s)
     SetValue(s);
@@ -159,7 +166,7 @@ void Mangled::SetValue(ConstString s, bool mangled) {
 
 void Mangled::SetValue(ConstString name) {
   if (name) {
-    if (cstring_is_mangled(name.GetCString())) {
+    if (cstring_is_mangled(name.GetStringRef())) {
       m_demangled.Clear();
       m_mangled = name;
     } else {
@@ -232,7 +239,7 @@ bool Mangled::DemangleWithRichManglingInfo(
   assert(m_mangled);
 
   // Check whether or not we are interested in this name at all.
-  ManglingScheme scheme = cstring_mangling_scheme(m_mangled.GetCString());
+  ManglingScheme scheme = GetManglingScheme(m_mangled.GetStringRef());
   if (skip_mangled_name && skip_mangled_name(m_mangled.GetStringRef(), scheme))
     return false;
 
@@ -300,7 +307,7 @@ Mangled::GetDemangledName(lldb::LanguageType language) const {
 
     // Don't bother running anything that isn't mangled
     const char *mangled_name = m_mangled.GetCString();
-    ManglingScheme mangling_scheme{cstring_mangling_scheme(mangled_name)};
+    ManglingScheme mangling_scheme = GetManglingScheme(m_mangled.GetStringRef());
     if (mangling_scheme != eManglingSchemeNone &&
         !m_mangled.GetMangledCounterpart(m_demangled)) {
       // We didn't already mangle this name, demangle it and if all goes well
@@ -405,6 +412,7 @@ size_t Mangled::MemorySize() const {
 // within those targets.
 lldb::LanguageType Mangled::GuessLanguage() const {
   ConstString mangled = GetMangledName();
+
   if (mangled) {
     const char *mangled_name = mangled.GetCString();
     if (CPlusPlusLanguage::IsCPPMangledName(mangled_name))

lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp

@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Demangle/ItaniumDemangle.h"
 
+#include "lldb/Core/Mangled.h"
 #include "lldb/Core/PluginManager.h"
 #include "lldb/Core/UniqueCStringMap.h"
 #include "lldb/DataFormatters/CXXFunctionPointer.h"
@@ -238,18 +239,16 @@ std::string CPlusPlusLanguage::MethodName::GetScopeQualifiedName() {
   return res;
 }
 
-bool CPlusPlusLanguage::IsCPPMangledName(const char *name) {
+bool CPlusPlusLanguage::IsCPPMangledName(llvm::StringRef name) {
   // FIXME!! we should really run through all the known C++ Language plugins
   // and ask each one if this is a C++ mangled name
 
-  if (name == nullptr)
+  Mangled::ManglingScheme scheme = Mangled::GetManglingScheme(name);
+
+  if (scheme == Mangled::eManglingSchemeNone)
     return false;
 
-  // MSVC style mangling
-  if (name[0] == '?')
   return true;
-
-  return (name[0] != '\0' && name[0] == '_' && name[1] == 'Z');
 }
 
 bool CPlusPlusLanguage::ExtractContextAndIdentifier(

lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h

@@ -101,7 +101,7 @@ public:
 
   static lldb_private::ConstString GetPluginNameStatic();
 
-  static bool IsCPPMangledName(const char *name);
+  static bool IsCPPMangledName(llvm::StringRef name);
 
   // Extract C++ context and identifier from a string using heuristic matching
   // (as opposed to

lldb/unittests/Core/MangledTest.cpp

@@ -37,6 +37,17 @@ TEST(MangledTest, ResultForValidName) {
   EXPECT_STREQ(ExpectedResult.GetCString(), TheDemangled.GetCString());
 }
 
+TEST(MangledTest, ResultForBlockInvocation) {
+  ConstString MangledName("___Z1fU13block_pointerFviE_block_invoke");
+  Mangled TheMangled(MangledName);
+  ConstString TheDemangled =
+      TheMangled.GetDemangledName(eLanguageTypeC_plus_plus);
+
+  ConstString ExpectedResult(
+      "invocation function for block in f(void (int) block_pointer)");
+  EXPECT_STREQ(ExpectedResult.GetCString(), TheDemangled.GetCString());
+}
+
 TEST(MangledTest, EmptyForInvalidName) {
   ConstString MangledName("_ZN1a1b1cmxktpEEvm");
   Mangled TheMangled(MangledName);