An unnecessary check for the range of a smi was being performed in

src/arm/code-stubs-arm.cc

 // Copyright 2012 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 4671 matching lines @@
   // A monomorphic cache hit or an already megamorphic state: invoke the
   // function without changing the state.
   __ cmp(r3, r1);
   __ b(eq, &done);
   __ CompareRoot(r3, Heap::kUndefinedValueRootIndex);
   __ b(eq, &done);
 
   // Special handling of the Array() function, which caches not only the
   // monomorphic Array function but the initial ElementsKind with special
   // sentinels
-  Handle<Object> terminal_kind_sentinel =
-      TypeFeedbackCells::MonomorphicArraySentinel(masm->isolate(),
-                                                  LAST_FAST_ELEMENTS_KIND);
   __ JumpIfNotSmi(r3, &miss);
-  __ cmp(r3, Operand(terminal_kind_sentinel));

[danno, 2013/06/13 15:19:44]

How about you turn this into:

  if (FLAG_debug_code) {
    __ cmp(r3, Operand(terminal_kind_sentinel));
    Check(le, "Array function sentinel is not an Elementskind");
  }

on this and other platforms?

-  __ b(gt, &miss);
   // Make sure the function is the Array() function
   __ LoadArrayFunction(r3);
   __ cmp(r1, r3);
   __ b(ne, &megamorphic);
   __ jmp(&done);
 
   __ bind(&miss);
 
   // A monomorphic miss (i.e, here the cache is not uninitialized) goes
   // megamorphic.
@@ skipping 2782 matching lines @@
     __ Jump(generic_construct_stub, RelocInfo::CODE_TARGET);
   }
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM