Support Int32 representation for selected binary operations.

tests/standalone/unboxed_int_converter_test.dart

+// Copyright (c) 2014, 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 UnboxedIntConverter for int32.
+
+import "package:expect/expect.dart";
+import "dart:typed_data";
+
+int32_to_mint(a, b) {
+  var sum = 0;
+  var j = 0;
+  for (var i = a; i <= b; i++) {

[Florian Schneider, 2014/08/27 09:36:51]

This test does not seem to cover all int32 operations. e.g. do we have any test
coverage with int32 phis?

[Vyacheslav Egorov (Google), 2014/08/27 11:45:37]

both `sum` and `j` are int32 phis here. 

I will add all supported operations into this test.

+    sum -= (j * ++j) & 0xff;
+  }
+
+  return 0xffffffff + sum;
+}
+
+mint_to_int32(a, c, d) {
+  return a * a * a * (c - d);
+}
+
+uint32_to_int32(a, c) {
+  return (a * a * a) * (c & 0xFFFFFFFF);
+
+}
+
+main() {
+  for (var j = 0; j < 10000; j++) {
+    Expect.equals(4294839503, int32_to_mint(0, 1000));
+    Expect.equals(-8, mint_to_int32(2, 0x100000000, 0x100000001));
+    Expect.equals(8, uint32_to_int32(2, 0x100000001));
+  }
+  Expect.equals(8 * 0x80000001, uint32_to_int32(2, 0x180000001));
+}