1843987 - Automatically tigger concurrent delazification for off-thread compilation if the option is set

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P3)

Description

[Tooru Fujisawa [:arai]]

Currently the concurrent delazification is triggered from ParseTask.
in order to move the off-thread compilation code to Gecko thread, the DelazifyTask or equivalent needs to be triggered from Gecko thread.

Comment 1

[Tooru Fujisawa [:arai]]

Given the concurrent delazification is triggered automatically inside bytecode compiler for on-main-thread compilation,
it's better aligning to it also in off-thread compilation.

Comment 2

[Tooru Fujisawa [:arai]]

The DelazifyTask::runtime field is used in the following places:

• js::CancelOffThreadDelazify called by JSRuntime::destroyRuntime
• WaitForAllDelazifyTasks called by CompileGlobalScriptToStencilAndMaybeInstantiate

the query in the latter can be done with ScriptSource, given CompileGlobalScriptToStencilAndMaybeInstantiate triggers the same delazification and it knows the ScriptSource.
the query in the former cannot be done with ScriptSource, given ScriptSource isn't associated with JSRuntime.

So, if we want to cancel delazify task on JSRuntime::destroyRuntime, we'll need to pass JSRuntime pointer via JS::FrontendContext.
but given the script cache is no longer strongly associated with runtime, it's not much necessary to explicitly wait in JSRuntime::destroyRuntime.
Also, given JSRuntime::destroyRuntime purges the cache, the DelazifyTask will soon stop when the current function gets delazified.

https://searchfox.org/mozilla-central/rev/3c7b40d1d74c26a82486f38b5828c3f3a43e05da/js/src/vm/Runtime.cpp#215,228

void JSRuntime::destroyRuntime() {
...
  caches().purgeStencils();

Comment 3

[Tooru Fujisawa [:arai]]

actually, we can just cancel DelazifyTask which has no runtime when a runtime is getting destroyed.

Comment 4

[Tooru Fujisawa [:arai]]

Attachment: Bug 1843987 - Automatically trigger concurrent delazification also for off-thread compilation if the CompileOptions flag is set. r?nbp!

Depends on D184357

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/cdc989c09e3d
Automatically trigger concurrent delazification also for off-thread compilation if the CompileOptions flag is set. r=nbp

Comment 6

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/cdc989c09e3d