From da298aa913754eb70cf2dc8fac0ed6b5ae72cfe9 Mon Sep 17 00:00:00 2001
From: Nico Weber <nicolasweber@gmx.de>
Date: Mon, 23 Sep 2019 13:13:37 +0000
Subject: [PATCH] llvm-undname: Add support for demangling typeinfo names

typeinfo names aren't symbols but string constant contents
stored in compiler-generated typeinfo objects, but llvm-cxxfilt
can demangle these for Itanium names.

In the MSVC ABI, these are just a '.' followed by a mangled
type -- this means they don't start with '?' like all MS-mangled
symbols do.

Differential Revision: https://reviews.llvm.org/D67851

llvm-svn: 372602
---
 llvm/include/llvm/Demangle/MicrosoftDemangle.h |  1 +
 llvm/lib/Demangle/MicrosoftDemangle.cpp        | 18 ++++++++++++++++++
 llvm/test/Demangle/invalid-manglings.test      |  5 +++++
 llvm/test/Demangle/ms-operators.test           |  3 +++
 4 files changed, 27 insertions(+)

diff --git a/llvm/include/llvm/Demangle/MicrosoftDemangle.h b/llvm/include/llvm/Demangle/MicrosoftDemangle.h
index 382e794..c6f26061 100644
--- a/llvm/include/llvm/Demangle/MicrosoftDemangle.h
+++ b/llvm/include/llvm/Demangle/MicrosoftDemangle.h
@@ -158,6 +158,7 @@ private:
                                     QualifiedNameNode *QN);
   SymbolNode *demangleDeclarator(StringView &MangledName);
   SymbolNode *demangleMD5Name(StringView &MangledName);
+  SymbolNode *demangleTypeinfoName(StringView &MangledName);
 
   VariableSymbolNode *demangleVariableEncoding(StringView &MangledName,
                                                StorageClass SC);
diff --git a/llvm/lib/Demangle/MicrosoftDemangle.cpp b/llvm/lib/Demangle/MicrosoftDemangle.cpp
index bf7d776..4be6e5a 100644
--- a/llvm/lib/Demangle/MicrosoftDemangle.cpp
+++ b/llvm/lib/Demangle/MicrosoftDemangle.cpp
@@ -783,8 +783,26 @@ SymbolNode *Demangler::demangleMD5Name(StringView &MangledName) {
   return S;
 }
 
+SymbolNode *Demangler::demangleTypeinfoName(StringView &MangledName) {
+  assert(MangledName.startsWith('.'));
+  MangledName.consumeFront('.');
+
+  TypeNode *T = demangleType(MangledName, QualifierMangleMode::Result);
+  if (Error || !MangledName.empty()) {
+    Error = true;
+    return nullptr;
+  }
+  return synthesizeVariable(Arena, T, "`RTTI Type Descriptor Name'");
+}
+
 // Parser entry point.
 SymbolNode *Demangler::parse(StringView &MangledName) {
+  // Typeinfo names are strings stored in RTTI data. They're not symbol names.
+  // It's still useful to demangle them. They're the only demangled entity
+  // that doesn't start with a "?" but a ".".
+  if (MangledName.startsWith('.'))
+    return demangleTypeinfoName(MangledName);
+
   if (MangledName.startsWith("??@"))
     return demangleMD5Name(MangledName);
 
diff --git a/llvm/test/Demangle/invalid-manglings.test b/llvm/test/Demangle/invalid-manglings.test
index 543c116..b772884 100644
--- a/llvm/test/Demangle/invalid-manglings.test
+++ b/llvm/test/Demangle/invalid-manglings.test
@@ -374,3 +374,8 @@
 ; CHECK-EMPTY:
 ; CHECK-NEXT: ??_P
 ; CHECK-NEXT: error: Invalid mangled name
+
+.?AUBase@@@8
+; CHECK-EMPTY:
+; CHECK-NEXT: .?AUBase@@@8
+; CHECK-NEXT: error: Invalid mangled name
diff --git a/llvm/test/Demangle/ms-operators.test b/llvm/test/Demangle/ms-operators.test
index 71a3a13..b940488 100644
--- a/llvm/test/Demangle/ms-operators.test
+++ b/llvm/test/Demangle/ms-operators.test
@@ -209,6 +209,9 @@
 ??_R0?AUBase@@@8
 ; CHECK: struct Base `RTTI Type Descriptor'
 
+.?AUBase@@
+; CHECK: struct Base `RTTI Type Descriptor Name'
+
 ??_R1A@?0A@EA@Base@@8
 ; CHECK: Base::`RTTI Base Class Descriptor at (0, -1, 0, 64)'
 
-- 
2.7.4