Bug 194693 – [JSC] Do not even allocate JIT worklists in non-JIT mode

• Status: RESOLVED
• Resolution: FIXED
• Component: New Bugs

[Yusuke Suzuki]

[JSC] Do not even allocate JIT worklists in non-JIT mode

[Yusuke Suzuki]

Created attachment 362102 [details]
Patch

[Mark Lam]

Comment on attachment 362102 [details]
Patch

r=me

[WebKit Commit Bot]

Comment on attachment 362102 [details]
Patch

Clearing flags on attachment: 362102

Committed r241582: <https://trac.webkit.org/changeset/241582>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/48104783>

[Saam Barati]

Comment on attachment 362102 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=362102&action=review

> Source/JavaScriptCore/jit/JITWorklist.cpp:339
> +            WTF::storeStoreFence();

Why? Doesn’t the once act as a barrier?

[Yusuke Suzuki]

Comment on attachment 362102 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=362102&action=review

>> Source/JavaScriptCore/jit/JITWorklist.cpp:339
>> +            WTF::storeStoreFence();
> 
> Why? Doesn’t the once act as a barrier?

VM::~VM calls existingGlobalWorklistOrNull. It should not see half-baked JITWorklist.
If the race happens and VM::~VM missed the worklist, it is OK since it means no plan associated to destroyed VM exists in the worklist.

[Yusuke Suzuki]

Comment on attachment 362102 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=362102&action=review

>>> Source/JavaScriptCore/jit/JITWorklist.cpp:339
>>> +            WTF::storeStoreFence();
>> 
>> Why? Doesn’t the once act as a barrier?
> 
> VM::~VM calls existingGlobalWorklistOrNull. It should not see half-baked JITWorklist.
> If the race happens and VM::~VM missed the worklist, it is OK since it means no plan associated to destroyed VM exists in the worklist.

The important thing is... existingGlobalWorklistOrNull does not have barrier!
I thought that DFG worklists have some mechanism guarding worklists against this race, but DFG worklist seems racy. I should put the fence to DFG/FTL worklists & Wasm worklist too.