1643948 - CacheIR: Optimize arguments[Symbol.iterator]

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, enhancement, P3)

Description

[Tom S. (please needinfo tschuster)]

The Symbol.iterator property is lazily resolved on the arguments object. This is why we need a specialized stub similar to what we have for length.

Comment 1

[André Bargull [:anba]]

Attachment: Bug 1643948 - Part 1: Reify the arguments object iterator in the resolve hook. r=jandem!

Both arguments objects resolve hook were defining the iterator property, but
didn't set the corresponding ITERATOR_OVERRIDDEN_BIT flag. We don't need to
apply a similar change for the other resolved properties, because they're
using the (Un)MappedArgGetter and (Un)MappedArgSetter property functions.

In preparation for part two, the code to retrieve ArrayValues was already
moved into a separate function.

Comment 2

[André Bargull [:anba]]

Attachment: Bug 1643948 - Part 2: Optimise arguments[Symbol.iterator] in CacheIR. r=jandem!

This change allows to retrieve arguments[Symbol.iterator] without calling the
resolve hook and without actually adding the iterator function to the arguments
object.

Depends on D91030

Comment 3

[André Bargull [:anba]]

Attachment: Bug 1643948 - Part 3: Transpile GuardArgumentsObjectNotOverriddenIterator. r=jandem!

Depends on D91031

Comment 4

[André Bargull [:anba]]

Attachment: Bug 1643948 - Part 4: Add missing JitSpew_Codegen calls. r=jandem!

And remove calls from helper functions like emitLoadTypedElementResult()
and emitStoreTypedElement().

Depends on D91032

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/cdbe54a4b28f
Part 1: Reify the arguments object iterator in the resolve hook. r=jandem
https://hg.mozilla.org/integration/autoland/rev/ebc80496d7c1
Part 2: Optimise arguments[Symbol.iterator] in CacheIR. r=jandem
https://hg.mozilla.org/integration/autoland/rev/e8a33b1a8a73
Part 3: Transpile GuardArgumentsObjectNotOverriddenIterator. r=jandem
https://hg.mozilla.org/integration/autoland/rev/3acf673e3bc1
Part 4: Add missing JitSpew_Codegen calls. r=jandem

Comment 6

[Natalia Csoregi [:nataliaCs]]

Backed out for hazard failures on CacheIR.cpp

backout: https://hg.mozilla.org/integration/autoland/rev/53277b7f7f25f07c0fa18213ff6dffbb802a12dc

push: https://treeherder.mozilla.org/#/jobs?repo=autoland&group_state=expanded&searchStr=linux%2Cx64%2Cdebug%2Cspidermonkey%2Cbuilds%2Chazard-linux64-shell-haz%2Fdebug%2Ch&revision=3acf673e3bc151db9160387f0fd0d09433577677&selectedTaskRun=NyJZWijATBqinc8m3vshIQ.1

failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=316717908&repo=autoland&lineNumber=7220

[task 2020-09-25T13:13:34.280Z] TinderboxPrint: rooting hazards<br/>1
[task 2020-09-25T13:13:34.280Z] TinderboxPrint: (unsafe references to unrooted GC pointers)<br/>74
[task 2020-09-25T13:13:34.280Z] TinderboxPrint: (unnecessary roots)<br/>1052
[task 2020-09-25T13:13:34.280Z] TinderboxPrint: missing expected hazards<br/>0
[task 2020-09-25T13:13:34.281Z] TinderboxPrint: heap write hazards<br/>0
[task 2020-09-25T13:13:34.282Z] TEST-UNEXPECTED-FAIL | hazards | unrooted 'args' of type 'js::ArgumentsObject*' live across GC call at js/src/jit/CacheIR.cpp:2035
[task 2020-09-25T13:13:34.282Z] TEST-UNEXPECTED-FAIL | hazards | 1 rooting hazards detected

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/adc3ef732895
Part 1: Reify the arguments object iterator in the resolve hook. r=jandem
https://hg.mozilla.org/integration/autoland/rev/37b19e77ff1b
Part 2: Optimise arguments[Symbol.iterator] in CacheIR. r=jandem
https://hg.mozilla.org/integration/autoland/rev/9ec497f02595
Part 3: Transpile GuardArgumentsObjectNotOverriddenIterator. r=jandem
https://hg.mozilla.org/integration/autoland/rev/a8e63273be0e
Part 4: Add missing JitSpew_Codegen calls. r=jandem

Comment 8

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/adc3ef732895
https://hg.mozilla.org/mozilla-central/rev/37b19e77ff1b
https://hg.mozilla.org/mozilla-central/rev/9ec497f02595
https://hg.mozilla.org/mozilla-central/rev/a8e63273be0e