Convert diamond shaped control flow into a single conditional instruction.

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;
+
+const POWER_OF_2 = 0x1000000000;
+
+bigPower(i) => (i == 11) ? 0 : POWER_OF_2;
+
+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);
+    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));
+  Expect.equals(3, f4(44));
+
+  Expect.equals(1, f5(0));
+  Expect.equals(0, f5(44));
+  Expect.equals(3, f6(0));
+  Expect.equals(2, f6(44));
+  Expect.equals(1, f7(null));
+  Expect.equals(0, f7(44));
+  Expect.equals(3, f8(null));
+  Expect.equals(2, f8(44));
+
+  Expect.equals(0, f9(0));
+  Expect.equals(1, f9(44));
+  Expect.equals(2, f10(0));
+  Expect.equals(3, f10(44));
+  Expect.equals(0, f11(null));
+  Expect.equals(1, f11(44));
+  Expect.equals(2, f12(null));
+  Expect.equals(3, f12(44));
+
+  Expect.equals(1, f13(0));
+  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));
+}