Lazy deopt without code patching.

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index 12dd5fa2f6fdcc37fd861a2de0c6adc4eb08164f..b724c02d76e7f61e4b08bb7fa0bfdea40f33ae9a 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -19,6 +19,7 @@
 #include "vm/os_thread.h"
 #include "vm/timer.h"
 #include "vm/token_position.h"
+#include "vm/growable_array.h"
 
 namespace dart {
 
@@ -70,6 +71,18 @@ class ThreadRegistry;
 class UserTag;
 
 
+class PendingLazyDeopt {
+ public:
+  PendingLazyDeopt(uword fp, uword pc) : fp_(fp), pc_(pc) { }
+  uword fp() { return fp_; }
+  uword pc() { return pc_; }
+
+ private:
+  uword fp_;
+  uword pc_;
+};
+
+
 class IsolateVisitor {
  public:
   IsolateVisitor() {}
@@ -390,6 +403,9 @@ class Isolate : public BaseIsolate {
     return object_id_ring_;
   }
 
+  MallocGrowableArray<PendingLazyDeopt>* pending_deopts() {
+    return pending_deopts_;
+  }
   bool IsDeoptimizing() const { return deopt_context_ != NULL; }
   DeoptContext* deopt_context() const { return deopt_context_; }
   void set_deopt_context(DeoptContext* value) {
@@ -740,6 +756,7 @@ class Isolate : public BaseIsolate {
   Dart_GcPrologueCallback gc_prologue_callback_;
   Dart_GcEpilogueCallback gc_epilogue_callback_;
   intptr_t defer_finalization_count_;
+  MallocGrowableArray<PendingLazyDeopt>* pending_deopts_;
   DeoptContext* deopt_context_;
 
   bool is_service_isolate_;