Revert "Simplify and fix implicit closure check, speed up Closure_equals"

runtime/lib/function.cc

Index: runtime/lib/function.cc
diff --git a/runtime/lib/function.cc b/runtime/lib/function.cc
index af6969d1a912bb1bbbe5a43b2871bca77dc4ebbd..0bd2c70d429b5d098b97b05524b2a60a447c9335 100644
--- a/runtime/lib/function.cc
+++ b/runtime/lib/function.cc
@@ -35,30 +35,33 @@ DEFINE_NATIVE_ENTRY(Closure_equals, 2) {
       Closure::CheckedHandle(zone, arguments->NativeArgAt(0));
   GET_NATIVE_ARGUMENT(Instance, other, arguments->NativeArgAt(1));
   ASSERT(!other.IsNull());
-  // For implicit instance closures compare receiver instance and function's
-  // name and owner (multiple function objects could exist for the same
-  // function due to hot reload).
-  // Objects of other closure kinds are unique, so use identity comparison.
-  if (receiver.raw() == other.raw()) {
-    return Bool::True().raw();
-  }
-  const Function& func_a = Function::Handle(zone, receiver.function());
-  if (func_a.IsImplicitInstanceClosureFunction()) {
-    if (other.IsClosure()) {
-      const Closure& other_closure = Closure::Cast(other);
-      const Function& func_b = Function::Handle(zone, other_closure.function());
-      if (func_b.IsImplicitInstanceClosureFunction()) {
+  if (receiver.raw() == other.raw()) return Bool::True().raw();
+  if (other.IsClosure()) {
+    const Function& func_a = Function::Handle(zone, receiver.function());
+    const Function& func_b =
+        Function::Handle(zone, Closure::Cast(other).function());
+    if (func_a.raw() == func_b.raw()) {
+      ASSERT(!func_a.IsImplicitStaticClosureFunction());
+      if (func_a.IsImplicitInstanceClosureFunction()) {
         const Context& context_a = Context::Handle(zone, receiver.context());
         const Context& context_b =
-            Context::Handle(zone, other_closure.context());
-        RawObject* receiver_a = context_a.At(0);
-        RawObject* receiver_b = context_b.At(0);
-        if ((receiver_a == receiver_b) &&
-            ((func_a.raw() == func_b.raw()) ||
-             ((func_a.name() == func_b.name()) &&
-              (func_a.Owner() == func_b.Owner())))) {
-          return Bool::True().raw();
-        }
+            Context::Handle(zone, Closure::Cast(other).context());
+        const Object& receiver_a = Object::Handle(zone, context_a.At(0));
+        const Object& receiver_b = Object::Handle(zone, context_b.At(0));
+        if (receiver_a.raw() == receiver_b.raw()) return Bool::True().raw();
+      }
+    } else if (func_a.IsImplicitInstanceClosureFunction() &&
+               func_b.IsImplicitInstanceClosureFunction()) {
+      // TODO(rmacnak): Patch existing tears off during reload instead.
+      const Context& context_a = Context::Handle(zone, receiver.context());
+      const Context& context_b =
+          Context::Handle(zone, Closure::Cast(other).context());
+      const Object& receiver_a = Object::Handle(zone, context_a.At(0));
+      const Object& receiver_b = Object::Handle(zone, context_b.At(0));
+      if ((receiver_a.raw() == receiver_b.raw()) &&
+          (func_a.name() == func_b.name()) &&
+          (func_a.Owner() == func_b.Owner())) {
+        return Bool::True().raw();
       }
     }
   }