Add a value range analysis phase to remove bounds checks.

tests/compiler/dart2js/value_range_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.
+
+#import("compiler_helper.dart");
+
+const int REMOVED = 0;
+const int ABOVE_ZERO = 1;
+const int BELOW_LENGTH = 2;
+const int KEPT = 3;
+
+final List TESTS = [
+"""
+main() {
+  var a = new List();
+  var sum = 0;
+  for (int i = 0; i < a.length; i++) {
+    sum += a[i];
+  }
+  return sum;
+}
+""",
+REMOVED,
+
+"""
+main(value) {
+  var a = new List();
+  var sum = 0;
+  for (int i = 0; i < value; i++) {
+    sum += a[i];
+  }
+  return sum;
+}
+""",
+ABOVE_ZERO,
+
+"""
+main(check) {
+  // Make sure value is an int.
+  var value = check ? 42 : 54;
+  var a = new List(value);
+  var sum = 0;
+  for (int i = 0; i < value; i++) {
+    sum += a[i];
+  }
+  return sum;
+}
+""",
+REMOVED,
+
+"""
+main() {
+  var a = new List();
+  return a[0];
+}
+""",
+KEPT,
+
+"""
+main() {
+  var a = new List();
+  return a.removeLast();
+}
+""",
+KEPT,
+
+"""
+main() {
+  var a = new List(4);
+  return a[0];
+}
+""",
+REMOVED,
+
+"""
+main() {
+  var a = new List(4);
+  return a.removeLast();
+}
+""",
+REMOVED,
+
+"""
+main(value) {
+  var a = new List(value);
+  return a[value];
+}
+""",
+KEPT,
+
+"""
+main(value) {
+  var a = new List(1024);
+  return a[1023 & value];
+}
+""",
+REMOVED,
+
+"""
+main(value) {
+  var a = new List(1024);
+  return a[1024 & value];
+}
+""",
+ABOVE_ZERO
+];
+
+expect(String code, int kind) {
+  String generated = compile(code);
+  switch (kind) {
+    case REMOVED:
+      Expect.isTrue(!generated.contains('ioore'));
+      break;
+
+    case ABOVE_ZERO:
+      Expect.isTrue(!generated.contains('> 0'));
+      break;
+
+    case BELOW_LENGTH:
+      Expect.isTrue(!generated.contains('||'));
+      break;
+
+    case KEPT:
+      Expect.isTrue(generated.contains('ioore'));
+      break;
+  }
+}
+
+
+main() {
+  for (int i = 0; i < TESTS.length;  i += 2) {
+    expect(TESTS[i], TESTS[i + 1]);
+  }
+}