- Use the simulator to do atomic operations that could also

runtime/vm/atomic.h

Index: runtime/vm/atomic.h
===================================================================
--- runtime/vm/atomic.h	(revision 41298)
+++ runtime/vm/atomic.h	(working copy)
@@ -8,6 +8,7 @@
 #include "platform/globals.h"
 
 #include "vm/allocation.h"
+#include "vm/simulator.h"
 
 namespace dart {
 
@@ -15,6 +16,8 @@
  public:
   // Atomically fetch the value at p and increment the value at p.
   // Returns the original value at p.
+  //
+  // NOTE: Not to be used for any atomic operations involving generated code.

[koda, 2014/10/27 14:05:10]

This is a bit vague. "involving memory locations that are accessed by generated
code" maybe?

[Ivan Posva, 2014/10/27 17:58:23]

Done.

   static uintptr_t FetchAndIncrement(uintptr_t* p);
 
   static uword CompareAndSwapWord(uword* ptr, uword old_value, uword new_value);
@@ -23,6 +26,10 @@
 
 }  // namespace dart
 
+// We need to use the simulator to ensure that atomic operations are observed
+// both in C++ and in generated code if the simulator is active.
+#include "vm/atomic_simulator.h"
+
 #if defined(TARGET_OS_ANDROID)
 #include "vm/atomic_android.h"
 #elif defined(TARGET_OS_LINUX)