Active smi-only optimizations for large array literals.

src/x64/ic-x64.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 691 matching lines @@
   __ bind(&fast_object_without_map_check);
   // Smi stores don't require further checks.
   Label non_smi_value;
   __ JumpIfNotSmi(rax, &non_smi_value);
   // It's irrelevant whether array is smi-only or not when writing a smi.
   __ movq(FieldOperand(rbx, rcx, times_pointer_size, FixedArray::kHeaderSize),
           rax);
   __ ret(0);
 
   __ bind(&non_smi_value);
-  if (FLAG_smi_only_arrays) {
-    // Writing a non-smi, check whether array allows non-smi elements.
-    // r9: receiver's map
-    __ CheckFastObjectElements(r9, &slow, Label::kNear);
-  }
+  // Writing a non-smi, check whether array allows non-smi elements.
+  // r9: receiver's map
+  __ CheckFastObjectElements(r9, &slow, Label::kNear);
   __ lea(rcx,
          FieldOperand(rbx, rcx, times_pointer_size, FixedArray::kHeaderSize));
   __ movq(Operand(rcx, 0), rax);
   __ movq(rdx, rax);
   __ RecordWrite(
       rbx, rcx, rdx, kDontSaveFPRegs, EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
   __ ret(0);
 
   __ bind(&fast_double_with_map_check);
   // Check for fast double array case. If this fails, call through to the
@@ skipping 972 matching lines @@
   Condition cc = *jmp_address == Assembler::kJncShortOpcode
       ? not_zero
       : zero;
   *jmp_address = static_cast<byte>(Assembler::kJccShortPrefix | cc);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64