v8/test/mjsunit/harmony/bigint/regress-tostring-2.js
Jakob Kummerow dcc6bd76a9 [bigint] Two more fixes for fast .toString()
Firstly, the fast path checking for applicability of the equality
"A/B = 0 with remainder A" must use the condition "A<B", not "A<=B".
Secondly, *all* early return paths must ensure that enough padding
'0' characters are written.

Fixed: chromium:1236694
Bug: v8:11515
Change-Id: I3fa7e17f5f3969ddbb5417b53abf3bff3fc1355b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3075365
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76139}
2021-08-06 17:08:05 +00:00

33 lines
1.5 KiB
JavaScript

// Copyright 2021 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Specific regression test for crbug.com/1236694.
let long = '1000000000000000000000000000000000000000000000'.repeat(20) + '0';
let short = '100000000000000000000000000000000000000000000'.repeat(20) + '0';
BigInt(long).toLocaleString();
BigInt(short).toLocaleString();
// Generalized to test a range of similar inputs. Considerations to keep
// execution times reasonable while testing interesting cases:
// - The number of zeros should grow large enough to potentially fill two
// entire digits (i.e. >= 38), which makes the recursion take the early
// termination path, which is worthy of test coverage.
// - The number of repeats should grow large enough to shift any bug-triggering
// bit pattern to any position in a digit, i.e. >= 64.
// - Fewer repeats may be easier to debug in case of failure, but likely don't
// provide additional test coverage, so we test very few distinct values.
// - To test the fast algorithm, (zeros+1)*repeats must be >= 810 or so.
function test(zeros, repeats) {
let chunk = '1' + '0'.repeat(zeros);
let input = chunk.repeat(repeats);
assertEquals(input, BigInt(input).toString(),
`bug for ${zeros} zeros repeated ${repeats} times`);
}
for (let zeros = 1; zeros < 50; zeros++) {
for (let repeats = 64; repeats > 0; repeats -= 20) {
test(zeros, repeats);
}
}
test(96, 11); // Found to hit the extra-early recursion termination path.