Revert "Revert "Make CXXNewExpr contain only a single initialier, and not hold the used constructor itself.""

This reintroduces commit r150682 with a fix for the Bullet benchmark crash.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150685 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index 7df8f6f..4843716 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -2351,10 +2351,20 @@
     Out << '_';
     mangleType(New->getAllocatedType());
     if (New->hasInitializer()) {
+      // FIXME: Does this mean "parenthesized initializer"?
       Out << "pi";
-      for (CXXNewExpr::const_arg_iterator I = New->constructor_arg_begin(),
-             E = New->constructor_arg_end(); I != E; ++I)
-        mangleExpression(*I);
+      const Expr *Init = New->getInitializer();
+      if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(Init)) {
+        // Directly inline the initializers.
+        for (CXXConstructExpr::const_arg_iterator I = CCE->arg_begin(),
+                                                  E = CCE->arg_end();
+             I != E; ++I)
+          mangleExpression(*I);
+      } else if (const ParenListExpr *PLE = dyn_cast<ParenListExpr>(Init)) {
+        for (unsigned i = 0, e = PLE->getNumExprs(); i != e; ++i)
+          mangleExpression(PLE->getExpr(i));
+      } else
+        mangleExpression(Init);
     }
     Out << 'E';
     break;