[lldb] Reinstate original guard variable check

The isGuardVariableSymbol option for ignoring Microsoft's ABI
was originally added to get the bots green, but now that we found
the actual issue (that we checked for prefix instead of suffix
in the MS ABI check), we should be able to properly implement
the guard variable check without any strange Microsoft exceptions.

llvm-svn: 368802

Author: Teemperor

lldb/source/Plugins/ExpressionParser/Clang/IRForTarget.cpp

@@ -156,12 +156,9 @@ clang::NamedDecl *IRForTarget::DeclForGlobal(GlobalValue *global_val) {
 }
 
 /// Returns true iff the mangled symbol is for a static guard variable.
-static bool isGuardVariableSymbol(llvm::StringRef mangled_symbol,
-                                  bool check_ms_abi = true) {
-  bool result = mangled_symbol.startswith("_ZGV"); // Itanium ABI guard variable
-  if (check_ms_abi)
-    result |= mangled_symbol.endswith("@4IA"); // Microsoft ABI
-  return result;
+static bool isGuardVariableSymbol(llvm::StringRef mangled_symbol) {
+  return mangled_symbol.startswith("_ZGV") || // Itanium ABI
+         mangled_symbol.endswith("@4IA");     // Microsoft ABI
 }
 
 bool IRForTarget::CreateResultVariable(llvm::Function &llvm_function) {
@@ -181,9 +178,8 @@ bool IRForTarget::CreateResultVariable(llvm::Function &llvm_function) {
   for (StringMapEntry<llvm::Value *> &value_symbol : value_symbol_table) {
     result_name = value_symbol.first();
 
-    // Check if this is a guard variable. It seems this causes some hiccups
-    // on Windows, so let's only check for Itanium guard variables.
-    bool is_guard_var = isGuardVariableSymbol(result_name, /*MS ABI*/ false);
+    // Check if this is a guard variable.
+    const bool is_guard_var = isGuardVariableSymbol(result_name);
 
     if (result_name.contains("$__lldb_expr_result_ptr") && !is_guard_var) {
       found_result = true;