ARM: Avoid duplicate vmla when merging vmul and vadd

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HYDROGEN_INSTRUCTIONS_H_
 #define V8_HYDROGEN_INSTRUCTIONS_H_
 
 #include "src/v8.h"
 
 #include "src/allocation.h"
@@ skipping 645 matching lines @@
   bool IsDefinedAfter(HBasicBlock* other) const;
 
   // Operands.
   virtual int OperandCount() = 0;
   virtual HValue* OperandAt(int index) const = 0;
   void SetOperandAt(int index, HValue* value);
 
   void DeleteAndReplaceWith(HValue* other);
   void ReplaceAllUsesWith(HValue* other);
   bool HasNoUses() const { return use_list_ == NULL; }
+  bool HasOneUse() const {
+    return use_list_ != NULL && use_list_->tail() == NULL;
+  }
   bool HasMultipleUses() const {
     return use_list_ != NULL && use_list_->tail() != NULL;
   }
   int UseCount() const;
 
   // Mark this HValue as dead and to be removed from other HValues' use lists.
   void Kill();
 
   int flags() const { return flags_; }
   void SetFlag(Flag f) { flags_ |= (1 << f); }
@@ skipping 3077 matching lines @@
     if (!IsCommutative()) return false;
 
     // Constant operands are better off on the right, they can be inlined in
     // many situations on most platforms.
     if (left()->IsConstant()) return true;
     if (right()->IsConstant()) return false;
 
     // Otherwise, if there is only one use of the right operand, it would be
     // better off on the left for platforms that only have 2-arg arithmetic
     // ops (e.g ia32, x64) that clobber the left operand.
-    return right()->UseCount() == 1;
+    return right()->HasOneUse();
   }
 
   HValue* BetterLeftOperand() {
     return AreOperandsBetterSwitched() ? right() : left();
   }
 
   HValue* BetterRightOperand() {
     return AreOperandsBetterSwitched() ? left() : right();
   }
 
@@ skipping 4028 matching lines @@
 };
 
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_