Restore back pointer from Instructions to Code

runtime/vm/raw_object.h

 // 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.
 
 #ifndef VM_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/atomic.h"
 #include "vm/globals.h"
@@ skipping 1066 matching lines @@
   Entry* first_entry() { return &ptr()->data()[0]; }
 
   friend class Object;
   friend class SnapshotReader;
 };
 
 
 class RawInstructions : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(Instructions);
 
+  RawObject** from() {
+    return reinterpret_cast<RawObject**>(&ptr()->code_);
+  }
+  RawCode* code_;
+  RawObject** to() {
+    return reinterpret_cast<RawObject**>(&ptr()->code_);
+  }
+
   int32_t size_;
 
   // Variable length data follows here.
   uint8_t* data() { OPEN_ARRAY_START(uint8_t, uint8_t); }
 
   // Private helper function used while visiting stack frames. The
   // code which iterates over dart frames is also called during GC and
   // is not allowed to create handles.
   static bool ContainsPC(RawInstructions* raw_instr, uword pc);
 
@@ skipping 1132 matching lines @@
   COMPILE_ASSERT(kExternalTypedDataInt8ArrayCid ==
                  kTypedDataInt8ArrayViewCid + 15);
   COMPILE_ASSERT(kByteBufferCid == kExternalTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kNullCid == kByteBufferCid + 1);
   return (kNullCid - kTypedDataInt8ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_