Bias commutative single-use register inputs and support lea adds

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index c09f261c2e1772e7bfe6548c01f0c5946a4eb8f2..c0cc9cfaf6181344199c2a3685631800299fd2ce 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -3394,13 +3394,21 @@ class HBinaryOperation: public HTemplateInstruction<3> {
 
   // TODO(kasperl): Move these helpers to the IA-32 Lithium
   // instruction sequence builder.
-  HValue* LeastConstantOperand() {
-    if (IsCommutative() && left()->IsConstant()) return right();
+  HValue* BetterCandidateForRegisterOperand() {
+    if (IsCommutative()) {
+      if (left()->IsConstant()) return right();
+      if (right()->IsConstant()) return left();
+      if (right()->UseCount() == 1) return right();
+    }
     return left();
   }
 
-  HValue* MostConstantOperand() {
-    if (IsCommutative() && left()->IsConstant()) return left();
+  HValue* WorseCandidateForRegisterOperand() {
+    if (IsCommutative()) {
+      if (left()->IsConstant()) return left();
+      if (right()->IsConstant()) return right();
+      if (right()->UseCount() == 1) return left();
+    }
     return right();
   }