Copy-on-write arrays.

src/ia32/macro-assembler-ia32.cc

 // Copyright 2006-2009 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 1446 matching lines @@
     bind(&skip);
   }
 }
 
 
 void MacroAssembler::Assert(Condition cc, const char* msg) {
   if (FLAG_debug_code) Check(cc, msg);
 }
 
 
+void MacroAssembler::AssertFastElements(Register elements) {
+  if (FLAG_debug_code) {
+    Label ok;
+    cmp(FieldOperand(elements, HeapObject::kMapOffset),
+        Immediate(Factory::fixed_array_map()));
+    j(equal, &ok);
+    cmp(FieldOperand(elements, HeapObject::kMapOffset),
+        Immediate(Factory::fixed_cow_array_map()));
+    j(equal, &ok);
+    Abort("JSObject with fast elements map has slow elements");
+    bind(&ok);
+  }
+}
+
+
 void MacroAssembler::Check(Condition cc, const char* msg) {
   Label L;
   j(cc, &L, taken);
   Abort(msg);
   // will not return here
   bind(&L);
 }
 
 
 void MacroAssembler::CheckStackAlignment() {
@@ skipping 194 matching lines @@
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32