1591600 - Move is-lazy state from JSFunction to BaseScript

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P2)

Description

[Ted Campbell [:tcampbell]]

To advance Bug 1529456, we can try to replace the JSFunction::isInterpretedLazy() logic with a IsLazyScript flag on BaseScript. This will remove the eventual-consistency issue of script clones and allow more simplifications in the JITs (since all clones of a function will be non-lazy if we observed the canonical function to be non lazy).

One issue is that LazySelfHosted functions still use the JSFunction::INTERPRETED_LAZY flag. We should consider if expanding the definition of LazySelfHostedScript to include flags is worthwhile to remove branching in the JITs.

Comment 1

[Ted Campbell [:tcampbell]]

Attachment: Bug 1591600 - Remove AutoAssertFunctionDelazificationCompletion

These checks are reliant on the details of current lazy-script handling and
interfere with removing the INTERPRETED_LAZY flag so remove them for now.

Comment 2

[Ted Campbell [:tcampbell]]

Attachment: Bug 1591600 - Remove uses of JSFunction::hasScript/hasLazyScript

JSFunction::hasScript is generally replaced by a new JSFunction::hasBytecode
helper. The hasScript case previously also matched incomplete functions so
extra checks are sometimes needed.

Depends on D65030

Comment 3

[Ted Campbell [:tcampbell]]

Attachment: Bug 1591600 - Replace JSFunction INTERPRETED_LAZY flag

Replace the INTERPRETED/INTERPRETED_LAZY flag with BASESCRIPT/SELFHOSTLAZY
flags. This delegates more of the responsibility onto the BaseScript itself
and will allow us to combine the lazy and non-lazy script instances in a
single BaseScript.

Depends on D65031

Comment 4

[Ted Campbell [:tcampbell]]

With these patches, the function no longer directly stores the is-lazy state bit. The eventual-consistency of function clones is still an issue though as functions each have a pointer to one of the lazy or non-lazy BaseScript. Once those instances are shared, this all becomes much simpler though.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/887c5a9b2bd0
Remove AutoAssertFunctionDelazificationCompletion r=mgaudet
https://hg.mozilla.org/integration/autoland/rev/1d5e317c2f05
Remove uses of JSFunction::hasScript/hasLazyScript r=mgaudet
https://hg.mozilla.org/integration/autoland/rev/a7f70eb61210
Replace JSFunction INTERPRETED_LAZY flag r=mgaudet

Comment 6

[Ted Campbell [:tcampbell]]

Attachment: Bug 1591600 - Follow-up clang-format fix in JSFunction.cpp. r?mgaudet

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/122b34044596
Follow-up clang-format fix in JSFunction.cpp. r=mgaudet

Comment 8

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/887c5a9b2bd0
https://hg.mozilla.org/mozilla-central/rev/1d5e317c2f05
https://hg.mozilla.org/mozilla-central/rev/a7f70eb61210
https://hg.mozilla.org/mozilla-central/rev/122b34044596