For background compilation we copy ICData so that it is immutable during comnpilation. However, we …

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 1384 matching lines @@
   friend class SnapshotReader;
 };
 
 
 class RawICData : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(ICData);
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->owner_);
   }
-  RawFunction* owner_;         // Parent/calling function of this IC.
-  RawString* target_name_;     // Name of target function.
+  RawObject* owner_;  // Parent/calling function or original IC of cloned IC.
+  RawString* target_name_;  // Name of target function.
   RawArray* args_descriptor_;  // Arguments descriptor.
-  RawArray* ic_data_;          // Contains class-ids, target and count.
+  RawArray* ic_data_;  // Contains class-ids, target and count.
   RawObject** to() {
     return reinterpret_cast<RawObject**>(&ptr()->ic_data_);
   }
   int32_t deopt_id_;     // Deoptimization id corresponding to this IC.
   uint32_t state_bits_;  // Number of arguments tested in IC, deopt reasons,
                          // is closure call, JS warning issued, range feedback.
 };
 
 
 class RawMegamorphicCache : public RawObject {
@@ skipping 850 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_