ARM64: Generate optimized code for Math.floor and Math.round with double outputs.

src/hydrogen-instructions.h

 // 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 954 matching lines @@
   // This function must be overridden for instructions with flag kUseGVN, to
   // compare the non-Operand parts of the instruction.
   virtual bool DataEquals(HValue* other) {
     UNREACHABLE();
     return false;
   }
 
   virtual Representation RepresentationFromInputs() {
     return representation();
   }
-  Representation RepresentationFromUses();
+  virtual Representation RepresentationFromUses();
   Representation RepresentationFromUseRequirements();
   bool HasNonSmiUse();
   virtual void UpdateRepresentation(Representation new_rep,
                                     HInferRepresentationPhase* h_infer,
                                     const char* reason);
   void AddDependantsToWorklist(HInferRepresentationPhase* h_infer);
 
   virtual void RepresentationChanged(Representation to) { }
 
   virtual Range* InferRange(Zone* zone);
@@ skipping 1663 matching lines @@
         default:
           UNREACHABLE();
           return Representation::None();
       }
     }
   }
 
   virtual Range* InferRange(Zone* zone) V8_OVERRIDE;
 
   virtual HValue* Canonicalize() V8_OVERRIDE;
+  virtual Representation RepresentationFromUses() V8_OVERRIDE;
   virtual Representation RepresentationFromInputs() V8_OVERRIDE;
 
   BuiltinFunctionId op() const { return op_; }
   const char* OpName() const;
 
   DECLARE_CONCRETE_INSTRUCTION(UnaryMathOperation)
 
  protected:
   virtual bool DataEquals(HValue* other) V8_OVERRIDE {
     HUnaryMathOperation* b = HUnaryMathOperation::cast(other);
     return op_ == b->op();
   }
 
  private:
+  // Indicates if we support a double (and int32) output for Math.floor and
+  // Math.round.
+  bool SupportsFlexibleFloorAndRound() const {
+#ifdef V8_TARGET_ARCH_ARM64
+    return true;
+#else
+    return false;
+#endif
+  }
   HUnaryMathOperation(HValue* context, HValue* value, BuiltinFunctionId op)
       : HTemplateInstruction<2>(HType::TaggedNumber()), op_(op) {
     SetOperandAt(0, context);
     SetOperandAt(1, value);
     switch (op) {
       case kMathFloor:
       case kMathRound:
+        if (SupportsFlexibleFloorAndRound()) {
+          SetFlag(kFlexibleRepresentation);
+        } else {
+          set_representation(Representation::Integer32());
+        }
+        break;
       case kMathClz32:
         set_representation(Representation::Integer32());
         break;
       case kMathAbs:
         // Not setting representation here: it is None intentionally.
         SetFlag(kFlexibleRepresentation);
         // TODO(svenpanne) This flag is actually only needed if representation()
         // is tagged, and not when it is an unboxed double or unboxed integer.
         SetChangesFlag(kNewSpacePromotion);
         break;
@@ skipping 4876 matching lines @@
   virtual bool IsDeletable() const V8_OVERRIDE { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_