Support use of external strings as inputs to LoadCodeUnitsInstr.

runtime/vm/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_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 6071 matching lines @@
  public:
   static uint16_t CharAt(const String& str, intptr_t index) {
     NoGCScope no_gc;
     return *CharAddr(str, index);
   }
 
   static void* GetPeer(const String& str) {
     return raw_ptr(str)->external_data_->peer();
   }
 
+  static intptr_t external_data_offset() {
+    return OFFSET_OF(RawExternalOneByteString, external_data_);
+  }
+
   // We use the same maximum elements for all strings.
   static const intptr_t kBytesPerElement = 1;
   static const intptr_t kMaxElements = String::kMaxElements;
 
   static intptr_t InstanceSize() {
     return String::RoundedAllocationSize(sizeof(RawExternalOneByteString));
   }
 
   static RawExternalOneByteString* New(const uint8_t* characters,
                                        intptr_t len,
@@ skipping 56 matching lines @@
  public:
   static uint16_t CharAt(const String& str, intptr_t index) {
     NoGCScope no_gc;
     return *CharAddr(str, index);
   }
 
   static void* GetPeer(const String& str) {
     return raw_ptr(str)->external_data_->peer();
   }
 
+  static intptr_t external_data_offset() {
+    return OFFSET_OF(RawExternalTwoByteString, external_data_);
+  }
+
   // We use the same maximum elements for all strings.
   static const intptr_t kBytesPerElement = 2;
   static const intptr_t kMaxElements = String::kMaxElements;
 
   static intptr_t InstanceSize() {
     return String::RoundedAllocationSize(sizeof(RawExternalTwoByteString));
   }
 
   static RawExternalTwoByteString* New(const uint16_t* characters,
                                        intptr_t len,
@@ skipping 1404 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_