Strict Mode assignment to read only property.

src/ic-inl.h

 // Copyright 2006-2008 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
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@@ skipping 58 matching lines @@
   // Convert target address to the code object. Code::GetCodeFromTargetAddress
   // is safe for use during GC where the map might be marked.
   Code* result = Code::GetCodeFromTargetAddress(target);
   ASSERT(result->is_inline_cache_stub());
   return result;
 }
 
 
 void IC::SetTargetAtAddress(Address address, Code* target) {
   ASSERT(target->is_inline_cache_stub() || target->is_compare_ic_stub());
+#ifdef DEBUG
+  // STORE_IC and KEYED_STORE_IC use Code::extra_ic_state() to mark
+  // ICs as strict mode. The strict-ness of the IC must be preserved.
+  Code* old_target = GetTargetAtAddress(address);
+  if (old_target->kind() == Code::STORE_IC ||
+      old_target->kind() == Code::KEYED_STORE_IC) {
+    ASSERT(old_target->extra_ic_state() == target->extra_ic_state());
+  }
+#endif

[Martin Maly, 2011/02/27 23:04:04]

This is a check that ICs do not migrate from strict mode to non-strict and vice
versa.

For added paranoia there is another check in StoreIC::set_target and
KeyedStoreIC::set_target and they are ultimately redundant. I am open to which
to keep and which to drop.

   Assembler::set_target_address_at(address, target->instruction_start());
 }
 
 
 InlineCacheHolderFlag IC::GetCodeCacheForObject(Object* object,
                                                 JSObject* holder) {
   if (object->IsJSObject()) {
     return GetCodeCacheForObject(JSObject::cast(object), holder);
   }
   // If the object is a value, we use the prototype map for the cache.
@@ skipping 22 matching lines @@
 JSObject* IC::GetCodeCacheHolder(Object* object, InlineCacheHolderFlag holder) {
   Object* map_owner = (holder == OWN_MAP ? object : object->GetPrototype());
   ASSERT(map_owner->IsJSObject());
   return JSObject::cast(map_owner);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_IC_INL_H_