Start using the overwrite mode from the full codegens to generate...

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
===================================================================
--- src/x64/full-codegen-x64.cc	(revision 5338)
+++ src/x64/full-codegen-x64.cc	(working copy)
@@ -1218,7 +1218,10 @@
   if (expr->is_compound()) {
     Location saved_location = location_;
     location_ = kAccumulator;
-    EmitBinaryOp(expr->binary_op(), Expression::kValue);
+    OverwriteMode mode = expr->value()->ResultOverwriteAllowed()
+        ? OVERWRITE_RIGHT
+        : NO_OVERWRITE;
+    EmitBinaryOp(expr->binary_op(), Expression::kValue, mode);
     location_ = saved_location;
   }
 
@@ -1261,12 +1264,16 @@
 
 
 void FullCodeGenerator::EmitBinaryOp(Token::Value op,
-                                     Expression::Context context) {
-  __ push(result_register());
-  GenericBinaryOpStub stub(op,
-                           NO_OVERWRITE,
-                           NO_GENERIC_BINARY_FLAGS);
-  __ CallStub(&stub);
+                                     Expression::Context context,
+                                     OverwriteMode mode) {
+  GenericBinaryOpStub stub(op, mode, NO_GENERIC_BINARY_FLAGS);
+  if (stub.ArgsInRegistersSupported()) {
+    __ pop(rdx);
+    stub.GenerateCall(masm_, rdx, rax);
+  } else {
+    __ push(result_register());
+    __ CallStub(&stub);
+  }
   Apply(context, rax);
 }
 
@@ -2646,9 +2653,7 @@
 
     case Token::SUB: {
       Comment cmt(masm_, "[ UnaryOperation (SUB)");
-      bool can_overwrite =
-          (expr->expression()->AsBinaryOperation() != NULL &&
-           expr->expression()->AsBinaryOperation()->ResultOverwriteAllowed());
+      bool can_overwrite = expr->expression()->ResultOverwriteAllowed();
       UnaryOverwriteMode overwrite =
           can_overwrite ? UNARY_OVERWRITE : UNARY_NO_OVERWRITE;
       GenericUnaryOpStub stub(Token::SUB, overwrite);
@@ -2662,9 +2667,7 @@
 
     case Token::BIT_NOT: {
       Comment cmt(masm_, "[ UnaryOperation (BIT_NOT)");
-      bool can_overwrite =
-          (expr->expression()->AsBinaryOperation() != NULL &&
-           expr->expression()->AsBinaryOperation()->ResultOverwriteAllowed());
+      bool can_overwrite = expr->expression()->ResultOverwriteAllowed();
       UnaryOverwriteMode overwrite =
           can_overwrite ? UNARY_OVERWRITE : UNARY_NO_OVERWRITE;
       GenericUnaryOpStub stub(Token::BIT_NOT, overwrite);
@@ -2780,7 +2783,7 @@
 
   // Inline smi case if we are in a loop.
   Label stub_call, done;
-  if (loop_depth() > 0) {
+  if (ShouldInlineSmiCase(expr->op())) {
     if (expr->op() == Token::INC) {
       __ SmiAddConstant(rax, rax, Smi::FromInt(1));
     } else {
@@ -2995,7 +2998,7 @@
   }
 
   VisitForValue(expr->left(), kStack);
-  switch (expr->op()) {
+  switch (op) {
     case Token::IN:
       VisitForValue(expr->right(), kStack);
       __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION);
@@ -3017,7 +3020,7 @@
       VisitForValue(expr->right(), kAccumulator);
       Condition cc = no_condition;
       bool strict = false;
-      switch (expr->op()) {
+      switch (op) {
         case Token::EQ_STRICT:
           strict = true;
           // Fall through.