Make bit-operations return a positive result.

tests/language/positive_bit_operations_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.
+
+constants() {
+  Expect.equals(0x80000000, 0x80000000 | 0);
+  Expect.equals(0x80000001, 0x80000000 | 1);
+  Expect.equals(0x80000000, 0x80000000 | 0x80000000);
+  Expect.equals(0xFFFFFFFF, 0xFFFF0000 | 0xFFFF);
+  Expect.equals(0x80000000, 0x80000000 & 0xFFFFFFFF);
+  Expect.equals(0x80000000, 0x80000000 & 0x80000000);
+  Expect.equals(0x80000000, 0x80000000 & 0xF0000000);
+  Expect.equals(0x80000000, 0xFFFFFFFF & 0x80000000);
+  Expect.equals(0x80000000, 0x80000000 ^ 0);
+  Expect.equals(0xFFFFFFFF, 0x80000000 ^ 0x7FFFFFFF);
+  Expect.equals(0xFFFFFFFF, 0x7FFFFFFF ^ 0x80000000);
+  Expect.equals(0xF0000000, 0x70000000 ^ 0x80000000);
+  Expect.equals(0x80000000, 1 << 31);
+  Expect.equals(0xFFFFFFF0, 0xFFFFFFF << 4);
+  Expect.equals(0x7FFFFFFF, 0xFFFFFFFF >> 1);
+  Expect.equals(0xFFFFFFFC,
+                ((((((0xFFFFFFF << 4) // 0xFFFFFFF0
+                                >> 1) // 0x7FFFFFF8
+                                | 0x80000000) // 0xFFFFFFF8
+                                >> 2) // 0x3FFFFFFE
+                                ^ 0x40000000) // 0x7FFFFFFE
+                                << 1));
+}
+
+foo(i) {
+  if (i != 0) {
+    y--;
+    foo(i - 1);
+    y++;
+  }
+}
+
+var y;
+
+// id returns [x] in a way that should be difficult to predict statically.
+id(x) {
+  y = x;
+  foo(10);
+  return y;
+}
+
+interceptors() {
+  Expect.equals(0x80000000, id(0x80000000) | id(0));
+  Expect.equals(0x80000001, id(0x80000000) | id(1));
+  Expect.equals(0x80000000, id(0x80000000) | id(0x80000000));
+  Expect.equals(0xFFFFFFFF, id(0xFFFF0000) | id(0xFFFF));
+  Expect.equals(0x80000000, id(0x80000000) & id(0xFFFFFFFF));
+  Expect.equals(0x80000000, id(0x80000000) & id(0x80000000));
+  Expect.equals(0x80000000, id(0x80000000) & id(0xF0000000));
+  Expect.equals(0x80000000, id(0xFFFFFFFF) & id(0x80000000));
+  Expect.equals(0x80000000, id(0x80000000) ^ id(0));
+  Expect.equals(0xFFFFFFFF, id(0x80000000) ^ id(0x7FFFFFFF));
+  Expect.equals(0xFFFFFFFF, id(0x7FFFFFFF) ^ id(0x80000000));
+  Expect.equals(0xF0000000, id(0x70000000) ^ id(0x80000000));
+  Expect.equals(0x80000000, id(1) << id(31));
+  Expect.equals(0xFFFFFFF0, id(0xFFFFFFF) << id(4));
+  Expect.equals(0x7FFFFFFF, id(0xFFFFFFFF) >> id(1));
+  Expect.equals(0xFFFFFFFC,
+                ((((((id(0xFFFFFFF) << 4) // 0xFFFFFFF0
+                                    >> 1) // 0x7FFFFFF8
+                                    | 0x80000000) // 0xFFFFFFF8
+                                    >> 2) // 0x3FFFFFFE
+                                    ^ 0x40000000) // 0x7FFFFFFE
+                                    << 1));
+}
+
+speculative() {
+  var a = id(0x80000000);
+  var b = id(0);
+  var c = id(1);
+  var d = id(0xFFFF0000);
+  var e = id(0xFFFF);
+  var f = id(0xFFFFFFFF);
+  var g = id(0xF0000000);
+  var h = id(0x7FFFFFFF);
+  var j = id(0x70000000);
+  var k = id(31);
+  var l = id(4);
+  var m = id(0xFFFFFFF);
+  for (int i = 0; i < 1; i++) {
+    Expect.equals(0x80000000, a | b);
+    Expect.equals(0x80000001, a | c);
+    Expect.equals(0x80000000, a | a);
+    Expect.equals(0xFFFFFFFF, d | e);
+    Expect.equals(0x80000000, a & f);
+    Expect.equals(0x80000000, a & a);
+    Expect.equals(0x80000000, a & g);
+    Expect.equals(0x80000000, f & a);
+    Expect.equals(0x80000000, a ^ b);
+    Expect.equals(0xFFFFFFFF, a ^ h);
+    Expect.equals(0xFFFFFFFF, h ^ a);
+    Expect.equals(0xF0000000, j ^ a);
+    Expect.equals(0x80000000, c << k);
+    Expect.equals(0xFFFFFFF0, m << l);
+    Expect.equals(0x7FFFFFFF, f >> c);
+    Expect.equals(0xFFFFFFFC,
+                  ((((((m << 4) // 0xFFFFFFF0
+                          >> 1) // 0x7FFFFFF8
+                          | 0x80000000) // 0xFFFFFFF8
+                          >> 2) // 0x3FFFFFFE
+                          ^ 0x40000000) // 0x7FFFFFFE
+                          << 1));
+  }
+}
+
+main() {
+  constants();
+  interceptors();
+  speculative();
+}