Fix BinaryOpIC implementation on ARM....

src/arm/codegen-arm.cc

 // Copyright 2010 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 6450 matching lines @@
       __ vcvt_f64_s32(d7, s15);
     } else {
       // Write Smi from r0 to r3 and r2 in double format.
       __ mov(r7, Operand(r0));
       ConvertToDoubleStub stub3(r3, r2, r7, r6);
       __ push(lr);
       __ Call(stub3.GetCode(), RelocInfo::CODE_TARGET);
       __ pop(lr);
     }
 
+    // HEAP_NUMBERS stub is slower than GENERIC on a pair of smis.
+    // r0 is known to be a smi. If r1 is also a smi then switch to GENERIC.
+    Label r1_is_not_smi;
+    if (runtime_operands_type_ == BinaryOpIC::HEAP_NUMBERS) {
+      __ tst(r1, Operand(kSmiTagMask));
+      __ b(ne, &r1_is_not_smi);
+      GenerateTypeTransition(masm);
+      __ jmp(&r1_is_smi);
+    }
+
     __ bind(&finished_loading_r0);
 
     // Move r1 to a double in r0-r1.
     __ tst(r1, Operand(kSmiTagMask));
     __ b(eq, &r1_is_smi);  // It's a Smi so don't check it's a heap number.
+    __ bind(&r1_is_not_smi);
     __ CompareObjectType(r1, r4, r4, HEAP_NUMBER_TYPE);
     __ b(ne, &slow);
     if (mode_ == OVERWRITE_LEFT) {
       __ mov(r5, Operand(r1));  // Overwrite this heap number.
     }
     if (use_fp_registers) {
       CpuFeatures::Scope scope(VFP3);
       // Load the double from tagged HeapNumber r1 to d6.
       __ sub(r7, r1, Operand(kHeapObjectTag));
       __ vldr(d6, r7, HeapNumber::kValueOffset);
@@ skipping 2840 matching lines @@
 
   // Just jump to runtime to add the two strings.
   __ bind(&string_add_runtime);
   __ TailCallRuntime(Runtime::kStringAdd, 2, 1);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal