1474348 - Fix two spec compliance bugs in the BlockOnPromise fast path

Status: RESOLVED FIXED

(Core :: JavaScript: Standard Library, enhancement)

Description

[André Bargull [:anba]]

This fast path [1] needs to check that the onFulfilled function doesn't return an object and that the |blockedPromise| doesn't have the PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS (PROMISE_FLAG_DEFAULT_RESOLVE_FUNCTION / PROMISE_FLAG_DEFAULT_REJECT_FUNCTION) flag set.


[1] https://searchfox.org/mozilla-central/rev/28daa2806c89684b3dfa4f0b551db1d099dda7c2/js/src/builtin/Promise.cpp#3315-3316

Comment 1

[André Bargull [:anba]]

Attachment: bug1474348-part1-accessors-and-flags.patch

Adds some additional accessor methods to the PromiseObject class and combines the PROMISE_FLAG_DEFAULT_RESOLVE_FUNCTION and PROMISE_FLAG_DEFAULT_REJECT_FUNCTION into a single PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS flag to avoid giving the impression that it is possible to have only one default resolving function.

Comment 2

[André Bargull [:anba]]

Attachment: bug1474348-part2-fix-fastpath.patch

Fixes the two bugs by ensuring that |onFulfilled| doesn't return an object and the blocked promise doesn't have the PROMISE_FLAG_DEFAULT_RESOLVING_FUNCTIONS flag set.

Sorry for the convoluted test cases, it seems like both bugs require a rather complex set-up to get triggered.

Comment 3

[Tooru Fujisawa [:arai]]

Comment on attachment 8990761 [details] [diff] [review]
bug1474348-part1-accessors-and-flags.patch

Review of attachment 8990761 [details] [diff] [review]:
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thanks!

Comment 4

[André Bargull [:anba]]

Try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=2133169d4fc2576043c38a0f2f92d2af7b13925a

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/f80f0ce62873
Part 1: Add accessors for Promise fixed slots and combine default resolving functions flags. r=arai
https://hg.mozilla.org/integration/mozilla-inbound/rev/ff0152ae26bd
Part 2: Don't use BlockOnPromise fast path with non-default resolving functions. r=arai

Comment 6

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/f80f0ce62873
https://hg.mozilla.org/mozilla-central/rev/ff0152ae26bd