1 files changed, 25 insertions, 3 deletions
diff --git a/llvm/lib/Demangle/MicrosoftDemangle.cpp b/llvm/lib/Demangle/MicrosoftDemangle.cpp
index 041d327..c1e6e14 100644
--- a/llvm/lib/Demangle/MicrosoftDemangle.cpp
+++ b/llvm/lib/Demangle/MicrosoftDemangle.cpp
@@ -747,16 +747,38 @@ SymbolNode *Demangler::demangleDeclarator(StringView &MangledName) {
 
 // Parser entry point.
 SymbolNode *Demangler::parse(StringView &MangledName) {
-  // We can't demangle MD5 names, just output them as-is.
-  // Also, MSVC-style mangled symbols must start with '?'.
   if (MangledName.startsWith("??@")) {
     // This is an MD5 mangled name.  We can't demangle it, just return the
     // mangled name.
+    // An MD5 mangled name is ??@ followed by 32 characters and a terminating @.
+    size_t MD5Last = MangledName.find('@', strlen("??@"));
+    if (MD5Last == StringView::npos) {
+      Error = true;
+      return nullptr;
+    }
+    const char* Start = MangledName.begin();
+    MangledName = MangledName.dropFront(MD5Last + 1);
+
+    // There are two additional special cases for MD5 names:
+    // 1. For complete object locators where the object name is long enough
+    //    for the object to have an MD5 name, the complete object locator is
+    //    called ??@...@??_R4@ (with a trailing "??_R4@" instead of the usual
+    //    leading "??_R4". This is handled here.
+    // 2. For catchable types, in versions of MSVC before 2015 (<1900) or after
+    //    2017.2 (>= 1914), the catchable type mangling is _CT??@...@??@...@8
+    //    instead of_CT??@...@8 with just one MD5 name. Since we don't yet
+    //    demangle catchable types anywhere, this isn't handled for MD5 names
+    //    either.
+    MangledName.consumeFront("??_R4@");
+
+    StringView MD5(Start, MangledName.begin());
     SymbolNode *S = Arena.alloc<SymbolNode>(NodeKind::Md5Symbol);
-    S->Name = synthesizeQualifiedName(Arena, MangledName);
+    S->Name = synthesizeQualifiedName(Arena, MD5);
+
     return S;
   }
 
+  // MSVC-style mangled symbols must start with '?'.
   if (!MangledName.startsWith('?')) {
     Error = true;
     return nullptr;