Porting r9392 to x64 (smi-only arrays).

src/x64/full-codegen-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 1437 matching lines @@
       continue;
     }
 
     if (!result_saved) {
       __ push(rax);
       result_saved = true;
     }
     VisitForAccumulatorValue(subexpr);
 
     // Store the subexpression value in the array's elements.
-    __ movq(rbx, Operand(rsp, 0));  // Copy of array literal.
-    __ movq(rbx, FieldOperand(rbx, JSObject::kElementsOffset));
+    __ movq(r8, Operand(rsp, 0));  // Copy of array literal.
+    __ movq(rbx, FieldOperand(r8, JSObject::kElementsOffset));
     int offset = FixedArray::kHeaderSize + (i * kPointerSize);
     __ movq(FieldOperand(rbx, offset), result_register());
 
+    Label no_map_change;
+    __ JumpIfSmi(result_register(), &no_map_change);
     // Update the write barrier for the array store.
-    __ RecordWriteField(rbx, offset, result_register(), rcx, kDontSaveFPRegs);
+    __ RecordWriteField(rbx, offset, result_register(), rcx,
+                        kDontSaveFPRegs,
+                        EMIT_REMEMBERED_SET,
+                        OMIT_SMI_CHECK);
+    if (FLAG_smi_only_arrays) {
+      __ movq(rdi, FieldOperand(rbx, JSObject::kMapOffset));
+      __ CheckFastSmiOnlyElements(rdi, &no_map_change, Label::kNear);
+      __ push(r8);
+      __ CallRuntime(Runtime::kNonSmiElementStored, 1);
+    }
+    __ bind(&no_map_change);
 
     PrepareForBailoutForId(expr->GetIdForElement(i), NO_REGISTERS);
   }
 
   if (result_saved) {
     context()->PlugTOS();
   } else {
     context()->Plug(rax);
   }
 }
@@ skipping 2709 matching lines @@
   *context_length = 0;
   return previous_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64