1434030 - Baldr: re-optimize stack limit and JSContext retrieval

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, enhancement)

Description

[Luke Wagner [:luke]]

Attachment: rm-cx-indirection

Now that the JSContext cooperative scheduling functionality is no longer needed, a given JSObject (and, transitively, wasm::Instance) can assume a fixed OS thread and JSContext*.  This allows removing several indirections in wasm that were added to allow a single TlsData* to bounce between threads.  (JIT stack overflow checks could be optimized as well.)

Comment 1

[Jakob Stoklund Olesen [:jolesen]]

Cretonne doesn't yet implement stack overflow checks. Tracked here: https://github.com/stoklund/cretonne/issues/234

Comment 2

[Luke Wagner [:luke]]

Attachment: rm-cx-indirection

... and of course that should be stackLimit*ForJitCode*().

Comment 3

[Jan de Mooij [:jandem]]

Comment on attachment 8946456 [details] [diff] [review]
rm-cx-indirection

Review of attachment 8946456 [details] [diff] [review]:
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I wonder if we need to remove the testing functions from the JS shell first, but we can worry about that if this breaks fuzzing.

Comment 4

[Luke Wagner [:luke]]

(In reply to Jan de Mooij [:jandem] from comment #3)
> I wonder if we need to remove the testing functions from the JS shell first,
> but we can worry about that if this breaks fuzzing.

When I landed the inverse patch, I tried to write a test for it that would have crashed but, iirc, it wasn't possible because the shell testing was so limited that you couldn't, e.g., hop a single JSObject between threads.  That's what got me worried/emailing that, if we ever actually used cooperative contexts, there were other bugs lurking.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/1802ba58c11a
Baldr: re-optimize stack limit and JSContext retrieval (r=jandem)

Comment 6

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/1802ba58c11a