Avoid calling ToRegister(register) when result is in register already, and re...

test/mjsunit/codegen-coverage.js

Index: test/mjsunit/codegen-coverage.js
===================================================================
--- test/mjsunit/codegen-coverage.js	(revision 4259)
+++ test/mjsunit/codegen-coverage.js	(working copy)
@@ -33,6 +33,13 @@
   return x;
 }
 
+function lookup(w, a) {
+  // This function tests a code path in the generation of a keyed load IC
+  // where the key and the value are both in the same register.
+  a = a;
+  w[a] = a;
+}
+
 function cover_codegen_paths() {
   var x = 1;
 
@@ -131,6 +138,12 @@
     assertEquals(1073741824, 1 - di);
 
     x = 3;
+    var w = { };
+    lookup(w, x);
+    lookup(w, x);
+    lookup(w, x);
+
+    x = 3;  // Terminate while loop.
   }
 }