From db8b81d2d33c1ab6457176ee43157e0aaf925be6 Mon Sep 17 00:00:00 2001
From: Martin Storsjo <martin@martin.st>
Date: Fri, 4 Oct 2019 07:22:37 +0000
Subject: [PATCH] Revert "[Symbolize] Use the local MSVC C++ demangler instead
 of relying on dbghelp. NFC."

This reverts SVN r373698, as it broke sanitizer tests, e.g. in
http://lab.llvm.org:8011/builders/sanitizer-windows/builds/52441.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@373701 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/DebugInfo/Symbolize/Symbolize.cpp        | 41 +++++++++++++++++++++++++---
 test/tools/llvm-symbolizer/coff-dwarf.test   |  3 ++
 test/tools/llvm-symbolizer/coff-exports.test |  5 ++++
 3 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/lib/DebugInfo/Symbolize/Symbolize.cpp b/lib/DebugInfo/Symbolize/Symbolize.cpp
index 389a8f743e9..8e1852bcf8e 100644
--- a/lib/DebugInfo/Symbolize/Symbolize.cpp
+++ b/lib/DebugInfo/Symbolize/Symbolize.cpp
@@ -35,6 +35,19 @@
 #include <cassert>
 #include <cstring>
 
+#if defined(_MSC_VER)
+#include <Windows.h>
+
+// This must be included after windows.h.
+#include <DbgHelp.h>
+#pragma comment(lib, "dbghelp.lib")
+
+// Windows.h conflicts with our COFF header definitions.
+#ifdef IMAGE_FILE_MACHINE_I386
+#undef IMAGE_FILE_MACHINE_I386
+#endif
+#endif
+
 namespace llvm {
 namespace symbolize {
 
@@ -511,11 +524,31 @@ LLVMSymbolizer::DemangleName(const std::string &Name,
                              const SymbolizableModule *DbiModuleDescriptor) {
   // We can spoil names of symbols with C linkage, so use an heuristic
   // approach to check if the name should be demangled.
-  // MSVC C++ mangled symbols start with '?', while itanium mangled ones
-  // start with _Z.
-  if (Name.substr(0, 2) == "_Z" || (!Name.empty() && Name.front() == '?'))
-    return demangle(Name);
+  if (Name.substr(0, 2) == "_Z") {
+    int status = 0;
+    char *DemangledName = itaniumDemangle(Name.c_str(), nullptr, nullptr, &status);
+    if (status != 0)
+      return Name;
+    std::string Result = DemangledName;
+    free(DemangledName);
+    return Result;
+  }
 
+#if defined(_MSC_VER)
+  if (!Name.empty() && Name.front() == '?') {
+    // Only do MSVC C++ demangling on symbols starting with '?'.
+    char DemangledName[1024] = {0};
+    DWORD result = ::UnDecorateSymbolName(
+        Name.c_str(), DemangledName, 1023,
+        UNDNAME_NO_ACCESS_SPECIFIERS |       // Strip public, private, protected
+            UNDNAME_NO_ALLOCATION_LANGUAGE | // Strip __thiscall, __stdcall, etc
+            UNDNAME_NO_THROW_SIGNATURES |    // Strip throw() specifications
+            UNDNAME_NO_MEMBER_TYPE | // Strip virtual, static, etc specifiers
+            UNDNAME_NO_MS_KEYWORDS | // Strip all MS extension keywords
+            UNDNAME_NO_FUNCTION_RETURNS); // Strip function return types
+    return (result == 0) ? Name : std::string(DemangledName);
+  }
+#endif
   if (DbiModuleDescriptor && DbiModuleDescriptor->isWin32Module())
     return std::string(demanglePE32ExternCFunc(Name));
   return Name;
diff --git a/test/tools/llvm-symbolizer/coff-dwarf.test b/test/tools/llvm-symbolizer/coff-dwarf.test
index 21d06b197ee..790763a2ddf 100644
--- a/test/tools/llvm-symbolizer/coff-dwarf.test
+++ b/test/tools/llvm-symbolizer/coff-dwarf.test
@@ -5,6 +5,9 @@ RUN:     | FileCheck %s
 RUN: llvm-symbolizer 0x5009 0x5038 -i --relative-address -obj="%p/Inputs/coff-dwarf.exe" \
 RUN:     | FileCheck %s
 
+This test relies on UnDecorateSymbolName, which is Windows-only.
+REQUIRES: target-windows, system-windows
+
 CHECK: foo(void)
 CHECK: coff-dwarf.cpp:7
 CHECK: bar(void)
diff --git a/test/tools/llvm-symbolizer/coff-exports.test b/test/tools/llvm-symbolizer/coff-exports.test
index a5d972f6e49..8678aae2960 100644
--- a/test/tools/llvm-symbolizer/coff-exports.test
+++ b/test/tools/llvm-symbolizer/coff-exports.test
@@ -5,6 +5,11 @@ RUN:   | FileCheck %s
 RUN: llvm-symbolizer 0x500A 0x5038 0x504B -i --relative-address -obj="%p/Inputs/coff-exports.exe" \
 RUN:   | FileCheck %s
 
+This test relies on UnDecorateSymbolName, which is Win32-only.
+REQUIRES: system-windows
+REQUIRES: target-windows
+FIXME: This test depends on host, not target.
+
 We get the expected stack trace, except 'foo' appears for the 'bar' frame
 because 'bar' isn't in the export table.
 
-- 
2.11.4.GIT