Free names of inputs of an instruction that is generate at use site. An input of an instruction tha…

tests/compiler/dart2js/ssa_phi_codegen_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // Test that parameters keep their names in the output.
 
 import 'compiler_helper.dart';
 
 const String TEST_ONE = r"""
 void foo(bar) {
   var a = 1;
@@ skipping 37 matching lines @@
     if (i == 9) a = false;
     for (var j = 0; b; j = j + 1) {
       if (j == 9) b = false;
     }
   }
   print(a);
   print(b);
 }
 """;
 
+const String TEST_FIVE = r"""
+void main() {
+  var hash = 0;
+  for (var i = 0; i == 0; i = i + 1) {
+    hash = hash + 10;

[ngeoffray, 2013/03/26 11:29:02]

The codegen recognizes that "hash + 10" can be generated at use site.

+    hash = hash + 42;

[ngeoffray, 2013/03/26 11:29:02]

We would generate:
hash0 = hash + 10 + 42

Now we generate:
hash = hash + 10 + 42.

+  }
+  print(t);
+}
+""";
+
 main() {
   compileAndMatchFuzzy(TEST_ONE, 'foo', "var x = x === true \\? 2 : 3;");
   compileAndMatchFuzzy(TEST_ONE, 'foo', "print\\(x\\);");
 
   compileAndMatchFuzzy(TEST_TWO, 'main', "x \\+= 10");
   compileAndMatchFuzzy(TEST_TWO, 'main', "\\+\\+x");
 
   // Check that we don't have 'd = d' (using regexp back references).
   compileAndDoNotMatchFuzzy(TEST_THREE, 'foo', '(x) = \1');
   compileAndMatchFuzzy(TEST_THREE, 'foo', 'return x');
   // Check that a store just after the declaration of the local
   // only generates one instruction.
   compileAndMatchFuzzy(TEST_THREE, 'foo', 'x = 42');
 
-  var generated = compile(TEST_FOUR, entry: 'foo');
   compileAndDoNotMatchFuzzy(TEST_FOUR, 'foo', '(x) = \1;');
+
+  compileAndDoNotMatch(TEST_FIVE, 'main', new RegExp('hash0'));
 }