Port optimization of comparison with a trivial LHS from ia32 to x64.

src/x64/codegen-x64.cc

Index: src/x64/codegen-x64.cc
===================================================================
--- src/x64/codegen-x64.cc	(revision 4928)
+++ src/x64/codegen-x64.cc	(working copy)
@@ -3855,8 +3855,17 @@
     default:
       UNREACHABLE();
   }
-  Load(left);
-  Load(right);
+
+  if (left->IsTrivial()) {
+    Load(right);
+    Result right_result = frame_->Pop();
+    frame_->Push(left);
+    frame_->Push(&right_result);

[Lasse Reichstein, 2010/06/24 08:59:48]

Could we reverse the comparison instead, and keep left on top of the stack?

[William Hesse, 2010/06/24 14:43:53]

I don't think so, because the ToNumber calls inside comparison have to happen in
a certain order.

+  } else {
+    Load(left);
+    Load(right);
+  }
+
   Comparison(node, cc, strict, destination());
 }