Skip canonicalization check in LStoreKeyedFastDoubleElement when it is not needed:

src/arm/lithium-codegen-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 3597 matching lines @@
 
 
 void LCodeGen::DoStoreKeyedFastDoubleElement(
     LStoreKeyedFastDoubleElement* instr) {
   DwVfpRegister value = ToDoubleRegister(instr->value());
   Register elements = ToRegister(instr->elements());
   Register key = no_reg;
   Register scratch = scratch0();
   bool key_is_constant = instr->key()->IsConstantOperand();
   int constant_key = 0;
-  Label not_nan;
 
   // Calculate the effective address of the slot in the array to store the
   // double value.
   if (key_is_constant) {
     constant_key = ToInteger32(LConstantOperand::cast(instr->key()));
     if (constant_key & 0xF0000000) {
       Abort("array index constant value too big.");
     }
   } else {
     key = ToRegister(instr->key());
   }
   int shift_size = ElementsKindToShiftSize(FAST_DOUBLE_ELEMENTS);
   Operand operand = key_is_constant
       ? Operand(constant_key * (1 << shift_size) +
                 FixedDoubleArray::kHeaderSize - kHeapObjectTag)
       : Operand(key, LSL, shift_size);
   __ add(scratch, elements, operand);
   if (!key_is_constant) {
     __ add(scratch, scratch,
            Operand(FixedDoubleArray::kHeaderSize - kHeapObjectTag));
   }
 
-  // Check for NaN. All NaNs must be canonicalized.
-  __ VFPCompareAndSetFlags(value, value);
+  if (instr->NeedsCanonicalization()) {
+    // Check for NaN. All NaNs must be canonicalized.
+    __ VFPCompareAndSetFlags(value, value);
+    // Only load canonical NaN if the comparison above set the overflow.
+    __ Vmov(value,
+            FixedDoubleArray::canonical_not_the_hole_nan_as_double(),
+            vs);
+  }
 
-  // Only load canonical NaN if the comparison above set the overflow.
-  __ Vmov(value, FixedDoubleArray::canonical_not_the_hole_nan_as_double(), vs);
-
-  __ bind(&not_nan);
   __ vstr(value, scratch, 0);
 }
 
 
 void LCodeGen::DoStoreKeyedSpecializedArrayElement(
     LStoreKeyedSpecializedArrayElement* instr) {
 
   Register external_pointer = ToRegister(instr->external_pointer());
   Register key = no_reg;
   ElementsKind elements_kind = instr->elements_kind();
@@ skipping 1487 matching lines @@
   __ sub(scratch, result, Operand(index, LSL, kPointerSizeLog2 - kSmiTagSize));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal