Improve internal compiler API so that OSR code is never installed on function.

runtime/lib/mirrors.cc

Index: runtime/lib/mirrors.cc
diff --git a/runtime/lib/mirrors.cc b/runtime/lib/mirrors.cc
index 1dade418b20d37dcac6e91577b4a9dfe5a4c9293..6668c4dc54c0062cd8c35fbcc4f6e60de6eabd1a 100644
--- a/runtime/lib/mirrors.cc
+++ b/runtime/lib/mirrors.cc
@@ -96,10 +96,10 @@ static void EnsureConstructorsAreCompiled(const Function& func) {
     UNREACHABLE();
   }
   if (!func.HasCode()) {
-    const Error& error =
-        Error::Handle(zone, Compiler::CompileFunction(thread, func));
-    if (!error.IsNull()) {
-      Exceptions::PropagateError(error);
+    const Object& result =

[Vyacheslav Egorov (Google), 2017/03/30 09:58:52]

There are a lot of places that do this. Maybe you need a helper?

Compile::EnsureCode(thread, func) {
  // ...  
}

notice that returning Null in such places is also an error - so maybe assert
that it does not happen. We expect to have code attached to the function after
this invocation.

Maybe even put something on the function itself:

Function::EnsureCode() {
 if (func.HasCode()) return;
 ...
}

[erikcorry, 2017/03/30 12:26:33]

Done.

+        Object::Handle(zone, Compiler::CompileFunction(thread, func));
+    if (result.IsError()) {
+      Exceptions::PropagateError(Error::Cast(result));
       UNREACHABLE();
     }
   }