Avoid redundant smi check for Math.abs

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 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 3416 matching lines @@
   Register input_reg = ToRegister(instr->value());
   __ testl(input_reg, input_reg);
   Label is_positive;
   __ j(not_sign, &is_positive, Label::kNear);
   __ negl(input_reg);  // Sets flags.
   DeoptimizeIf(negative, instr->environment());
   __ bind(&is_positive);
 }
 
 
+void LCodeGen::EmitInteger64MathAbs(LMathAbs* instr) {
+  Register input_reg = ToRegister(instr->value());
+  __ testq(input_reg, input_reg);
+  Label is_positive;
+  __ j(not_sign, &is_positive, Label::kNear);
+  __ neg(input_reg);  // Sets flags.
+  DeoptimizeIf(negative, instr->environment());
+  __ bind(&is_positive);
+}
+
+
 void LCodeGen::DoMathAbs(LMathAbs* instr) {
   // Class for deferred case.
   class DeferredMathAbsTaggedHeapNumber: public LDeferredCode {
    public:
     DeferredMathAbsTaggedHeapNumber(LCodeGen* codegen, LMathAbs* instr)
         : LDeferredCode(codegen), instr_(instr) { }
     virtual void Generate() {
       codegen()->DoDeferredMathAbsTaggedHeapNumber(instr_);
     }
     virtual LInstruction* instr() { return instr_; }
    private:
     LMathAbs* instr_;
   };
 
   ASSERT(instr->value()->Equals(instr->result()));
   Representation r = instr->hydrogen()->value()->representation();
 
   if (r.IsDouble()) {
     XMMRegister scratch = xmm0;
     XMMRegister input_reg = ToDoubleRegister(instr->value());
     __ xorps(scratch, scratch);
     __ subsd(scratch, input_reg);
     __ andpd(input_reg, scratch);
   } else if (r.IsInteger32()) {
     EmitIntegerMathAbs(instr);
+  } else if (r.IsSmi()) {
+    EmitInteger64MathAbs(instr);
   } else {  // Tagged case.
     DeferredMathAbsTaggedHeapNumber* deferred =
         new(zone()) DeferredMathAbsTaggedHeapNumber(this, instr);
     Register input_reg = ToRegister(instr->value());
     // Smi check.
     __ JumpIfNotSmi(input_reg, deferred->entry());
     __ SmiToInteger32(input_reg, input_reg);
     EmitIntegerMathAbs(instr);
     __ Integer32ToSmi(input_reg, input_reg);
     __ bind(deferred->exit());
@@ skipping 2102 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64