ARM: Support record write stubs for incremental marking.

src/arm/macro-assembler-arm.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 421 matching lines @@
 
   // Skip barrier if writing a smi.
   if (smi_check == INLINE_SMI_CHECK) {
     JumpIfSmi(value, &done);
   }
 
   // Although the object register is tagged, the offset is relative to the start
   // of the object, so so offset must be a multiple of kPointerSize.
   ASSERT(IsAligned(offset, kPointerSize));
 
-  add(dst, object, Operand(offset));
+  add(dst, object, Operand(offset - kHeapObjectTag));
   if (emit_debug_code()) {
     Label ok;
-    JumpIfNotSmi(dst, &ok);
+    tst(dst, Operand((1 << kPointerSizeLog2) - 1));
+    b(eq, &ok);
     stop("Unaligned cell in write barrier");
     bind(&ok);
   }
 
   RecordWrite(object,
               dst,
               value,
               lr_status,
               save_fp,
               remembered_set_action,
@@ skipping 2921 matching lines @@
 void CodePatcher::EmitCondition(Condition cond) {
   Instr instr = Assembler::instr_at(masm_.pc_);
   instr = (instr & ~kCondMask) | cond;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM