Copy-on-write arrays.

src/arm/macro-assembler-arm.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 1549 matching lines @@
 void MacroAssembler::AssertRegisterIsRoot(Register reg,
                                           Heap::RootListIndex index) {
   if (FLAG_debug_code) {
     LoadRoot(ip, index);
     cmp(reg, ip);
     Check(eq, "Register did not match expected root");
   }
 }
 
 
+void MacroAssembler::AssertFastElements(Register elements) {
+  if (FLAG_debug_code) {
+    ASSERT(!elements.is(ip));
+    Label ok;
+    push(elements);
+    ldr(elements, FieldMemOperand(elements, HeapObject::kMapOffset));
+    LoadRoot(ip, Heap::kFixedArrayMapRootIndex);
+    cmp(elements, ip);
+    b(eq, &ok);
+    LoadRoot(ip, Heap::kFixedCOWArrayMapRootIndex);
+    cmp(elements, ip);
+    b(eq, &ok);
+    Abort("JSObject with fast elements map has slow elements");
+    bind(&ok);
+    pop(elements);
+  }
+}
+
+
 void MacroAssembler::Check(Condition cc, const char* msg) {
   Label L;
   b(cc, &L);
   Abort(msg);
   // will not return here
   bind(&L);
 }
 
 
 void MacroAssembler::Abort(const char* msg) {
@@ skipping 337 matching lines @@
 
 void CodePatcher::Emit(Address addr) {
   masm()->emit(reinterpret_cast<Instr>(addr));
 }
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM