Add instruction tags to saved ICData (debug mode only).

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 1460 matching lines @@
   RawObject** to_precompiled_snapshot() {
     return reinterpret_cast<RawObject**>(&ptr()->args_descriptor_);
   }
   RawObject* owner_;  // Parent/calling function or original IC of cloned IC.
   RawObject** to() {
     return reinterpret_cast<RawObject**>(&ptr()->owner_);
   }
   int32_t deopt_id_;     // Deoptimization id corresponding to this IC.
   uint32_t state_bits_;  // Number of arguments tested in IC, deopt reasons,
                          // range feedback.
+#if defined(TAG_IC_DATA)
+  intptr_t tag_;  // Debugging, verifying that the icdata is assigned to the
+                  // same instruction again. Store -1 or Instruction::Tag.
+#endif
 };
 
 
 class RawMegamorphicCache : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(MegamorphicCache);
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->buckets_);
   }
   RawArray* buckets_;
@@ skipping 876 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_