Introduce read buffer for external strings when using charAt (ia32).

src/objects-debug.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 362 matching lines @@
 void String::StringVerify() {
   CHECK(IsString());
   CHECK(length() >= 0 && length() <= Smi::kMaxValue);
   if (IsSymbol()) {
     CHECK(!HEAP->InNewSpace(this));
   }
   if (IsConsString()) {
     ConsString::cast(this)->ConsStringVerify();
   } else if (IsSlicedString()) {
     SlicedString::cast(this)->SlicedStringVerify();
+  } else if (IsExternalString()) {
+    ExternalString::cast(this)->ExternalStringVerify();
   }
 }
 
 
 void ConsString::ConsStringVerify() {
   CHECK(this->first()->IsString());
   CHECK(this->second() == GetHeap()->empty_string() ||
         this->second()->IsString());
   CHECK(this->length() >= String::kMinNonFlatLength);
   if (this->IsFlat()) {
     // A flat cons can only be created by String::SlowTryFlatten.
     // Afterwards, the first part may be externalized.
     CHECK(this->first()->IsSeqString() || this->first()->IsExternalString());
   }
 }
 
 
 void SlicedString::SlicedStringVerify() {
   CHECK(!this->parent()->IsConsString());
   CHECK(!this->parent()->IsSlicedString());
   CHECK(this->length() >= SlicedString::kMinLength);
 }
 
 
+void ExternalString::ExternalStringVerify() {
+  if (IsBuffered()) {
+    CHECK(length() >= kMinBufferedStringLength);
+    int index = buffer_index();
+    CHECK(index == kInvalidBufferIndex || (index >= 0 && index < length()));
+  }
+}
+
+
 void JSFunction::JSFunctionVerify() {
   CHECK(IsJSFunction());
   VerifyObjectField(kPrototypeOrInitialMapOffset);
   VerifyObjectField(kNextFunctionLinkOffset);
   CHECK(code()->IsCode());
   CHECK(next_function_link()->IsUndefined() ||
         next_function_link()->IsJSFunction());
 }
 
 
@@ skipping 430 matching lines @@
         ASSERT(e->IsUndefined());
       }
     }
   }
 }
 
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal