Re-landing of "replace TrySync with Metadata".

runtime/vm/exceptions.h

Index: runtime/vm/exceptions.h
diff --git a/runtime/vm/exceptions.h b/runtime/vm/exceptions.h
index c2a3350042b24ec8941869ff52528da1d6f4e385..67a8ffcd7aeb6d1bdcec5e1314de322962b8c48b 100644
--- a/runtime/vm/exceptions.h
+++ b/runtime/vm/exceptions.h
@@ -102,6 +102,65 @@ struct ExceptionHandlerInfo {
   int8_t is_generated;         // True if this is a generated handler.
 };
 
+
+class CatchEntryState {
+ public:
+  enum { kCatchEntryStateIsMove = 1, kCatchEntryStateDestShift = 1 };
+
+  CatchEntryState() : data(NULL), ref_count(NULL) {}
+  explicit CatchEntryState(intptr_t* data_)
+      : data(data_), ref_count(new intptr_t(1)) {}

[Florian Schneider, 2017/03/09 16:33:32]

Style: Private fields end with _. Rename parameter to 'data' and the member to
'data_'

[Dmitry Olshansky, 2017/03/13 12:26:30]

Done.

+
+  CatchEntryState(const CatchEntryState& state) { Copy(state); }
+
+  ~CatchEntryState() { Destroy(); }
+
+  CatchEntryState& operator=(const CatchEntryState& state) {
+    Destroy();
+    Copy(state);
+    return *this;
+  }
+
+  bool Empty() { return ref_count == NULL; }
+
+  intptr_t Pairs() { return data[0]; }
+
+  intptr_t Src(intptr_t i) { return data[1 + 2 * i]; }
+
+  intptr_t Dest(intptr_t i) {
+    return data[2 + 2 * i] >> kCatchEntryStateDestShift;
+  }
+
+  bool isMove(intptr_t i) { return data[2 + 2 * i] & kCatchEntryStateIsMove; }
+
+ private:
+  void Destroy() {
+    if (ref_count != NULL) {
+      (*ref_count)--;
+      if (*ref_count == 0) {
+        delete ref_count;
+        delete[] data;
+      }
+    }
+  }
+
+  void Copy(const CatchEntryState& state) {
+    data = state.data;
+    ref_count = state.ref_count;
+    if (ref_count != NULL) {
+      (*ref_count)++;
+    }
+  }
+
+  // Data has the following format:
+  // 0 - number of pairs in this state
+  // 1-2 - 1st encoded src,dest pair
+  // 3-4 - 2nd pair
+  // ....
+  intptr_t* data;
+  intptr_t* ref_count;

[Florian Schneider, 2017/03/09 16:33:32]

s/ref_count/ref_count_/g

[Dmitry Olshansky, 2017/03/13 12:26:31]

Done.

+};
+
 }  // namespace dart
 
 #endif  // RUNTIME_VM_EXCEPTIONS_H_