Support IfThenElse instruction pattern for arbitrary smi constants.

tests/language/if_conversion_vm_test.dart

 // Copyright (c) 2013, 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 if-convertion pass in the optimizing compiler.
 
 import "package:expect/expect.dart";
 
 f1(i) => (i == 0) ? 0 : 1;
 f2(i) => (i == 0) ? 2 : 3;
 f3(i) => (i == null) ? 0 : 1;
 f4(i) => (i == null) ? 2 : 3;
 
 f5(i) => (i != 0) ? 0 : 1;
 f6(i) => (i != 0) ? 2 : 3;
 f7(i) => (i != null) ? 0 : 1;
 f8(i) => (i != null) ? 2 : 3;
 
 f9(i) => identical(i, 0) ? 0 : 1;
 f10(i) => identical(i, 0) ? 2 : 3;
 f11(i) => identical(i, null) ? 0 : 1;
 f12(i) => identical(i, null) ? 2 : 3;
 
 f13(i) => !identical(i, 0) ? 0 : 1;
 f14(i) => !identical(i, 0) ? 2 : 3;
 f15(i) => !identical(i, null) ? 0 : 1;
 f16(i) => !identical(i, null) ? 2 : 3;

[Florian Schneider, 2013/04/12 15:18:52]

Maybe add ad test for the cases 

!power_of_two && true_value == 0

power_of_two && true_value != 0

[Vyacheslav Egorov (Google), 2013/04/12 15:26:34]

Done.

 
 const POWER_OF_2 = 0x1000000000;
 
 bigPower(i) => (i == 11) ? 0 : POWER_OF_2;
 
+cse(i) {
+  final a = i == 0 ? 0 : 1;
+  final b = i == 0 ? 2 : 3;
+  return a + b;
+}
+
 main() {
   for (var i = 0; i < 10000; i++) {
     f1(i);
     f2(i);
     f3(i);
     f4(i);
     f5(i);
     f6(i);
     f7(i);
     f8(i);
     f9(i);
     f10(i);
     f11(i);
     f12(i);
     f13(i);
     f14(i);
     f15(i);
     f16(i);
+    cse(i);
     bigPower(i);
   }
 
   Expect.equals(0, f1(0));
   Expect.equals(1, f1(44));
   Expect.equals(2, f2(0));
   Expect.equals(3, f2(44));
   Expect.equals(0, f3(null));
   Expect.equals(1, f3(44));
   Expect.equals(2, f4(null));
@@ skipping 21 matching lines @@
   Expect.equals(0, f13(44));
   Expect.equals(3, f14(0));
   Expect.equals(2, f14(44));
   Expect.equals(1, f15(null));
   Expect.equals(0, f15(44));
   Expect.equals(3, f16(null));
   Expect.equals(2, f16(44));
 
   Expect.equals(0, bigPower(11));
   Expect.equals(POWER_OF_2, bigPower(12));
+
+  Expect.equals(2, cse(0));
+  Expect.equals(4, cse(1));
 }