[lldb] Add support for demangling D symbols

This is part of https://github.com/dlang/projects/issues/81 .

This patch enables support for D programming language demangler by using a
pretty printed stacktrace with demangled D symbols, when present.

Signed-off-by: Luís Ferreira <contact@lsferreira.net>

Reviewed By: JDevlieghere, teemperor

Differential Revision: https://reviews.llvm.org/D110578

lldb/include/lldb/Core/Mangled.h

@@ -44,7 +44,8 @@ public:
     eManglingSchemeNone = 0,
     eManglingSchemeMSVC,
     eManglingSchemeItanium,
-    eManglingSchemeRustV0
+    eManglingSchemeRustV0,
+    eManglingSchemeD
   };
 
   /// Default constructor.

lldb/source/Core/Mangled.cpp

@@ -45,6 +45,9 @@ Mangled::ManglingScheme Mangled::GetManglingScheme(llvm::StringRef const name) {
   if (name.startswith("_R"))
     return Mangled::eManglingSchemeRustV0;
 
+  if (name.startswith("_D"))
+    return Mangled::eManglingSchemeD;
+
   if (name.startswith("_Z"))
     return Mangled::eManglingSchemeItanium;
 
@@ -185,6 +188,19 @@ static char *GetRustV0DemangledStr(const char *M) {
   return demangled_cstr;
 }
 
+static char *GetDLangDemangledStr(const char *M) {
+  char *demangled_cstr = llvm::dlangDemangle(M);
+
+  if (Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_DEMANGLE)) {
+    if (demangled_cstr && demangled_cstr[0])
+      LLDB_LOG(log, "demangled dlang: {0} -> \"{1}\"", M, demangled_cstr);
+    else
+      LLDB_LOG(log, "demangled dlang: {0} -> error: failed to demangle", M);
+  }
+
+  return demangled_cstr;
+}
+
 // Explicit demangling for scheduled requests during batch processing. This
 // makes use of ItaniumPartialDemangler's rich demangle info
 bool Mangled::DemangleWithRichManglingInfo(
@@ -244,7 +260,8 @@ bool Mangled::DemangleWithRichManglingInfo(
   }
 
   case eManglingSchemeRustV0:
-    // Rich demangling scheme is not supported for Rust
+  case eManglingSchemeD:
+    // Rich demangling scheme is not supported
     return false;
   }
   llvm_unreachable("Fully covered switch above!");
@@ -278,6 +295,9 @@ ConstString Mangled::GetDemangledName() const {
       case eManglingSchemeRustV0:
         demangled_name = GetRustV0DemangledStr(mangled_name);
         break;
+      case eManglingSchemeD:
+        demangled_name = GetDLangDemangledStr(mangled_name);
+        break;
       case eManglingSchemeNone:
         llvm_unreachable("eManglingSchemeNone was handled already");
       }

lldb/source/Symbol/Symtab.cpp

@@ -248,10 +248,8 @@ static bool lldb_skip_name(llvm::StringRef mangled,
 
   // No filters for this scheme yet. Include all names in indexing.
   case Mangled::eManglingSchemeMSVC:
-    return false;
-
-  // No filters for this scheme yet. Include all names in indexing.
   case Mangled::eManglingSchemeRustV0:
+  case Mangled::eManglingSchemeD:
     return false;
 
   // Don't try and demangle things we can't categorize.

lldb/unittests/Core/MangledTest.cpp

@@ -72,6 +72,24 @@ TEST(MangledTest, EmptyForInvalidRustV0Name) {
   EXPECT_STREQ("", the_demangled.GetCString());
 }
 
+TEST(MangledTest, ResultForValidDLangName) {
+  ConstString mangled_name("_Dmain");
+  Mangled the_mangled(mangled_name);
+  ConstString the_demangled = the_mangled.GetDemangledName();
+
+  ConstString expected_result("D main");
+  EXPECT_STREQ(expected_result.GetCString(), the_demangled.GetCString());
+}
+
+TEST(MangledTest, EmptyForInvalidDLangName) {
+  ConstString mangled_name("_DDD");
+  Mangled the_mangled(mangled_name);
+  ConstString the_demangled = the_mangled.GetDemangledName();
+
+  EXPECT_STREQ("", the_demangled.GetCString());
+}
+
+
 TEST(MangledTest, NameIndexes_FindFunctionSymbols) {
   SubsystemRAII<FileSystem, HostInfo, ObjectFileELF, SymbolFileSymtab>
       subsystems;