Fixes a couple problems with GC of unoptimized code.

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
===================================================================
--- runtime/vm/code_generator.cc	(revision 30197)
+++ runtime/vm/code_generator.cc	(working copy)
@@ -1343,9 +1343,15 @@
   if (FLAG_use_osr && (interrupt_bits == 0)) {
     DartFrameIterator iterator;
     StackFrame* frame = iterator.NextFrame();
-    const Function& function = Function::Handle(frame->LookupDartFunction());
+    const Code& code = Code::ZoneHandle(frame->LookupDartCode());
+    const Function& function = Function::Handle(code.function());
     ASSERT(!function.IsNull());
-    if (!CanOptimizeFunction(function, isolate)) return;
+    if (!function.HasCode()) {

[Ivan Posva, 2013/11/16 00:06:21]

Code should not be detachable as it is live on the stack.

[zra, 2013/11/18 18:54:33]

Changed to ASSERT.

+      function.ReattachCode(code);
+    }
+    if (!CanOptimizeFunction(function, isolate)) {
+      return;
+    }
     intptr_t osr_id =
         Code::Handle(function.unoptimized_code()).GetDeoptIdForOsr(frame->pc());
     if (FLAG_trace_osr) {
@@ -1356,9 +1362,12 @@
     }
 
     const Code& original_code = Code::Handle(function.CurrentCode());
+    ASSERT(!original_code.IsNull());
     const Error& error =
         Error::Handle(Compiler::CompileOptimizedFunction(function, osr_id));
-    if (!error.IsNull()) Exceptions::PropagateError(error);
+    if (!error.IsNull()) {
+      Exceptions::PropagateError(error);
+    }
 
     const Code& optimized_code = Code::Handle(function.CurrentCode());
     // The current code will not be changed in the case that the compiler