1654991 - Move construction/assignment of nsTArray is too complex

Status: RESOLVED FIXED

(Core :: XPCOM, task)

Description

[Simon Giesecke [:sg] [he/him]]

Move construction/assignment (and similarly Assign/AppendElements operations moving from a source array) should be simple operations. However, right now they are based on SwapArrayElements, which due to its generality is quite complex. This can be simplified based on the knowledge that the target array is empty. For move construction, this can even be further simplified when we know that the target array is not an AutoTArray.

Comment 1

[Simon Giesecke [:sg] [he/him]]

Attachment: Bug 1654991 - Simplify move constructor of nsTArray_Impl. r=#xpcom-reviewers

Comment 2

[Simon Giesecke [:sg] [he/him]]

Attachment: Bug 1654991 - Provide and use special case of ShrinkCapacityToZero. r=#xpcom-reviewers

Depends on D84804

Comment 3

[Simon Giesecke [:sg] [he/him]]

Attachment: Bug 1654991 - Simplify moving operator=, Assign and AppendElements. r=#xpcom-reviewers

Depends on D84805

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/cf3bfb91d98c
Simplify move constructor of nsTArray_Impl. r=froydnj
https://hg.mozilla.org/integration/autoland/rev/6a7964ba549f
Provide and use special case of ShrinkCapacityToZero. r=froydnj
https://hg.mozilla.org/integration/autoland/rev/a353dd5b3f08
Simplify moving operator=, Assign and AppendElements. r=froydnj

Comment 5

[Noemi Erli[:noemi_erli]]

Backed out 4 changesets (Bug 1654992, Bug 1654991) for causing timeous in mask-opacity-1e.html

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&group_state=expanded&resultStatus=testfailed%2Cbusted%2Cexception&revision=11f0f54c6e0a641470e6fba29733b3ab764df3ef&selectedTaskRun=aYbsuHJtQCuppxmgE3P_BA.0

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=311901321&repo=autoland&lineNumber=2840

Backout: https://hg.mozilla.org/integration/autoland/rev/61c16b78c2513fb0c6f552ee5fddd1c1648105a2

Comment 6

[Simon Giesecke [:sg] [he/him]]

The defect was in the patch for Bug 1654992, which I now fixed.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/58b72de320e1
Simplify move constructor of nsTArray_Impl. r=froydnj
https://hg.mozilla.org/integration/autoland/rev/649d2bc6ad86
Provide and use special case of ShrinkCapacityToZero. r=froydnj
https://hg.mozilla.org/integration/autoland/rev/6f09ee25da28
Simplify moving operator=, Assign and AppendElements. r=froydnj

Comment 8

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/58b72de320e1
https://hg.mozilla.org/mozilla-central/rev/649d2bc6ad86
https://hg.mozilla.org/mozilla-central/rev/6f09ee25da28