786146 - IonMonkey: eagerly generate stubs/wrappers, store in runtime

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Brian Hackett [Laid off!]]

Attachment: patch (01854460aa68)

The main difficulty with bug 785762 is the need to get IonCode objects for various stubs (VM function wrappers, etc.) that are lazily generated and need to be constructed on the main thread.  It would be much simpler for off thread compilation if these objects were eagerly generated and guaranteed present during code generation, so that the compilation thread does not have to try to allocate any IonCode objects nor defer a linking step to later.

The attached patch eagerly generates all stubs/wrappers which were formerly lazily generated.  On my machine this takes about .2ms and generates about 16KB of code (plus the IonCode objects themselves).  This is a little steep when done per compartment, so this patch also moves this data into a new IonRuntime.  The stubs are allocated in the atoms compartment and, once created, are not collected until the runtime is destroyed.

Comment 1

[Nicolas B. Pierron [:nbp]]

Comment on attachment 655857 [details] [diff] [review]
patch (01854460aa68)

Review of attachment 655857 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/ion/Ion.cpp
@@ +142,2 @@
>  {
> +    SwitchToCompartment sc(cx, cx->runtime->atomsCompartment);

I agree with the final goal, but either this compartment should be renamed or these executable pieces of code should be allocated in their own compartment.

Comment 2

[Brian Hackett [Laid off!]]

Pushed, with a couple tweaks to unbitrot off thread compilation.

https://hg.mozilla.org/integration/mozilla-inbound/rev/589b6766b99a

Comment 3

[Ryan VanderMeulen [:RyanVM]]

This blew up tests pretty bad. Backed out.
https://hg.mozilla.org/integration/mozilla-inbound/rev/f5e702c39521

See the TBPL push for logs of the bustage.
https://tbpl.mozilla.org/?tree=Mozilla-Inbound&rev=589b6766b99a

Comment 4

[Brian Hackett [Laid off!]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/6ba78023b367

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/6ba78023b367