dart-sdk/tests/language/regress/regress11793_test.dart
Robert Nystrom 67539c2faf Migrate language_2/regress to NNBD.
Change-Id: I318742cd4303d70c0625c9efd98bb01087aa5de4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150466
Commit-Queue: Bob Nystrom <rnystrom@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
2020-06-13 01:00:22 +00:00

48 lines
1.6 KiB
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.
// Regression test for dart2js, whose value range analysis phase
// assumed loop phis that were integer necessarily had integer inputs.
var array = const [0, 0.5];
var globalB = array[0];
var otherArray = [5];
main() {
var b = globalB;
var a = b + 1;
if (otherArray[0] == 0) {
// Use a non-existing selector to prevent adding a bailout check.
(a as dynamic).noSuch();
a = otherArray[0];
}
// Use [a] to make sure it does not become dead code.
var f = array[a as int];
// Add an integer check on [b].
var d = array[b as int];
// This instruction will be GVN to the same value as [a].
// By being GVN'ed, [e] will have its type changed from integer
// to number: because of the int type check on [b], we know
// [: b + 1 :] returns an integer.
// However we update this instruction with the previous [: b + 1 :]
// that did not have that information and therefore only knows that
// the instruction returns a number.
var e = b + 1;
// Introduce a loop phi that has [e] as header input, and [e++] as
// update input. By having [e] as input, dart2js will compute an
// integer type for the phi. However, after GVN, [e] becomes a
// number.
while (otherArray[0] == 0) {
// Use [e] as an index for an array so that the value range
// analysis tries to compute a range for [e].
otherArray[e as int] = (d + f) as int;
e++;
}
}