1614041 - Allow parsing modules using stencils rather than GC objects.

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P2)

Description

[Matthew Gaudet (he/him) [:mgaudet]]

We need to be able to parse modules without requiring the allocation of GC'd objects.

Comment 1

[Ted Campbell [:tcampbell]]

The ModuleObject allocation needs to be handled, but this is similar to the standalone JSFunction case and should be straightforward.

The import/export map is currently built of JSObjects that are allocated in the middle of parsing. We need a stencil abstraction for the following types:

• RequestedModuleObject
• ImportEntryObject
• ExportEntryObject
  These are currently aggregated into ArrayObjects that are attached to the ModuleObject.

Some sort of Import/ExportMap Stencil data structure probably needs to be defined.

Comment 2

[Ted Campbell [:tcampbell]]

Attachment: Bug 1614041 - Defer ModuleBuilder GC allocations

Introduce StencilModuleEntry type to replace {Import,Export}EntryObject
during parsing. Avoid allocating those GC objects until the initModule call.

Comment 3

[Ted Campbell [:tcampbell]]

Attachment: Bug 1614041 - Do not allocate ModuleObject until after parsing

Defer the ModuleObject::functionDeclarations list initiailization until after
parsing.

Depends on D83206

Comment 4

[Ted Campbell [:tcampbell]]

Attachment: Bug 1614041 - Stop using ModuleObject* in ScopeCreationData

Similar to what is done for FunctionScope, defer the initialization of
ModuleScope::Data::module field until creating concrete scope.

Depends on D83206

Comment 5

[Ted Campbell [:tcampbell]]

Attachment: Bug 1614041 - Store FunctionDeclarations in StencilModuleMetadata

Use StencilModuleMetadata to hold module function-declarations list so that a
ModuleObject is no longer needed to perform parsing.

Depends on D83269

Comment 6

[Ted Campbell [:tcampbell]]

Attachment: Bug 1614041 - Move ModuleObject allocation into Stencil instantiation

Depends on D83270

Comment 7

[Ted Campbell [:tcampbell]]

Attachment: Bug 1614041 - Stop storing binding name in module function-decl list

The binding name is by definition the explicitName of the JSFunction so do
not store a copy of it. This avoids needing to trace that anymore.

Depends on D83269

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5db78863ff43
Defer ModuleBuilder GC allocations r=arai
https://hg.mozilla.org/integration/autoland/rev/73a1977876d1
Stop using ModuleObject* in ScopeCreationData r=mgaudet
https://hg.mozilla.org/integration/autoland/rev/c66757095dd4
Stop storing binding name in module function-decl list r=arai
https://hg.mozilla.org/integration/autoland/rev/24520be1a1ce
Store FunctionDeclarations in StencilModuleMetadata r=arai
https://hg.mozilla.org/integration/autoland/rev/32d800de8502
Move ModuleObject allocation into Stencil instantiation r=arai

Comment 9

[Atila Butkovits]

Backed outfor causing assertion failure at jsapi.cpp.

Backout link: https://hg.mozilla.org/integration/autoland/rev/5974b9e65af447c1d1b6918ea7887822f05c9a02

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&selectedTaskRun=VIAF_qhcSTSW3lv9yqoYAA.0&resultStatus=testfailed%2Cbusted%2Cexception&revision=32d800de8502b505408a347cb562c7963ab50192

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=309675182&repo=autoland&lineNumber=1778

Comment 10

[Ted Campbell [:tcampbell]]

JS_SetElement cannot be used on helper-threads, so I have restored the behaviour to use NativeObject::initDenseElement. I also modified the AssertHeapIsIdle check to disallow helper threads and verify no further issues. I will open a bug to permanently land these checks since they would have caught the problem sooner.

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/deb22e4b7e1e
Defer ModuleBuilder GC allocations r=arai
https://hg.mozilla.org/integration/autoland/rev/7d5c34919a24
Stop using ModuleObject* in ScopeCreationData r=mgaudet
https://hg.mozilla.org/integration/autoland/rev/ec3d556893bc
Stop storing binding name in module function-decl list r=arai
https://hg.mozilla.org/integration/autoland/rev/0776aaa8e255
Store FunctionDeclarations in StencilModuleMetadata r=arai
https://hg.mozilla.org/integration/autoland/rev/7eaf75ab590a
Move ModuleObject allocation into Stencil instantiation r=arai

Comment 12

[Dorel Luca [:dluca]]

Backed out 5 changesets (bug 1614041) for Spidermonkey failure on gecko/js/src/vm/NativeObject.h. CLOSED TREE

Log:
https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=309684554&repo=autoland&lineNumber=3966

Push with failures:
https://treeherder.mozilla.org/#/jobs?repo=autoland&group_state=expanded&revision=7eaf75ab590a297f8acc56cfec2cc43dcdf1dc3a

Backout:
https://hg.mozilla.org/integration/autoland/rev/45605357f44cedf5d3d6544750c68d482dca0844

Comment 13

[Jan de Mooij [:jandem]]

(In reply to Ted Campbell [:tcampbell] from comment #10)

I also modified the AssertHeapIsIdle check to disallow helper threads and verify no further issues.

See also the CHECK_THREAD macro where we explicitly allow helper thread contexts... Maybe it's time to change that. But all this is why I'm pushing for removing helper thread JSContexts completely in the future.

Comment 14

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a9af5a14e497
Defer ModuleBuilder GC allocations r=arai
https://hg.mozilla.org/integration/autoland/rev/8823ae6243b7
Stop using ModuleObject* in ScopeCreationData r=mgaudet
https://hg.mozilla.org/integration/autoland/rev/e08aadd71f4d
Stop storing binding name in module function-decl list r=arai
https://hg.mozilla.org/integration/autoland/rev/5927f5feaebf
Store FunctionDeclarations in StencilModuleMetadata r=arai
https://hg.mozilla.org/integration/autoland/rev/29ff06b4a609
Move ModuleObject allocation into Stencil instantiation r=arai

Comment 15

[Alexandru Michis [:malexandru]]

https://hg.mozilla.org/mozilla-central/rev/a9af5a14e497
https://hg.mozilla.org/mozilla-central/rev/8823ae6243b7
https://hg.mozilla.org/mozilla-central/rev/e08aadd71f4d
https://hg.mozilla.org/mozilla-central/rev/5927f5feaebf
https://hg.mozilla.org/mozilla-central/rev/29ff06b4a609