Don't use eax on x64. :)

src/x64/lithium-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 1511 matching lines @@
                                  LInstruction* instr) {
   // Change context if needed.
   bool change_context =
       (graph()->info()->closure()->context() != function->context()) ||
       scope()->contains_with() ||
       (scope()->num_heap_slots() > 0);
   if (change_context) {
     __ movq(rsi, FieldOperand(rdi, JSFunction::kContextOffset));
   }
 
-  // Set eax to arguments count if adaption is not needed. Assumes that eax
+  // Set rax to arguments count if adaption is not needed. Assumes that rax
   // is available to write to at this point.
   if (!function->NeedsArgumentsAdaption()) {
     __ Set(rax, arity);
   }
 
   LPointerMap* pointers = instr->pointer_map();
   RecordPosition(pointers->position());
 
   // Invoke function.
   if (*function == *graph()->info()->closure()) {
     __ CallSelf();
   } else {
     __ call(FieldOperand(rdi, JSFunction::kCodeEntryOffset));
   }
 
   // Setup deoptimization.
   RegisterLazyDeoptimization(instr);
 
   // Restore context.
   __ movq(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
 }
 
 
 void LCodeGen::DoCallConstantFunction(LCallConstantFunction* instr) {
-  ASSERT(ToRegister(instr->result()).is(eax));
+  ASSERT(ToRegister(instr->result()).is(rax));
   __ Move(rdi, instr->function());
   CallKnownFunction(instr->function(), instr->arity(), instr);
 }
 
 
 void LCodeGen::DoDeferredMathAbsTaggedHeapNumber(LUnaryMathOperation* instr) {
   Abort("Unimplemented: %s", "DoDeferredMathAbsTaggedHeapNumber");
 }
 
 
@@ skipping 469 matching lines @@
 
 void LCodeGen::DoOsrEntry(LOsrEntry* instr) {
   Abort("Unimplemented: %s", "DoOsrEntry");
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64