Modifies assertion for possibly null code pointer.

runtime/vm/pages.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/pages.h"
 
 #include "platform/assert.h"
 #include "vm/compiler_stats.h"
 #include "vm/gc_marker.h"
 #include "vm/gc_sweeper.h"
@@ skipping 366 matching lines @@
     page = page->next();
   }
   page = large_pages_;
   while (page != NULL) {
     page->WriteProtect(read_only);
     page = page->next();
   }
 }
 
 
-
 class CodeDetacherVisitor : public ObjectVisitor {
  public:
   explicit CodeDetacherVisitor(Isolate* isolate) : ObjectVisitor(isolate) { }
 
   virtual void VisitObject(RawObject* obj);
 
  private:
+  static bool MayDetachCode(const Function& fn);
   DISALLOW_COPY_AND_ASSIGN(CodeDetacherVisitor);
 };
 
 
+bool CodeDetacherVisitor::MayDetachCode(const Function& fn) {
+  return fn.HasCode() &&  // Not already detached.
+         !fn.HasOptimizedCode() &&
+         !fn.HasBreakpoint() &&
+         (fn.usage_counter() > 0);
+}
+
+
 void CodeDetacherVisitor::VisitObject(RawObject* raw_obj) {
   Isolate* isolate = Isolate::Current();
   HANDLESCOPE(isolate);
   const Object& obj = Object::Handle(raw_obj);
   if (obj.GetClassId() == kFunctionCid) {
     const Function& fn = Function::Cast(obj);
-    if (!fn.HasOptimizedCode() &&
-        !fn.HasBreakpoint() &&
-        fn.HasCode() &&  // Not already detached.
-        (fn.usage_counter() > 0)) {
+    if (CodeDetacherVisitor::MayDetachCode(fn)) {
       fn.set_usage_counter(fn.usage_counter() / 2);
       if (fn.usage_counter() == 0) {
         if (FLAG_log_code_drop) {
           const String& name = String::Handle(fn.name());
           OS::Print("Detaching code for function %s\n", name.ToCString());
         }
         fn.DetachCode();
       }
     }
   }
@@ skipping 231 matching lines @@
     return 0;
   } else {
     ASSERT(total_time >= gc_time);
     int result= static_cast<int>((static_cast<double>(gc_time) /
                              static_cast<double>(total_time)) * 100);
     return result;
   }
 }
 
 }  // namespace dart