[webkit-reviews] review granted: [Bug 185438] Deferred firing of structure transition watchpoints is racy : [Attachment 339886] Patch

[bugzilla-daemon at webkit.org]

Saam Barati <sbarati at apple.com> has granted Michael Saboff
<msaboff at apple.com>'s request for review:
Bug 185438: Deferred firing of structure transition watchpoints is racy
https://bugs.webkit.org/show_bug.cgi?id=185438

Attachment 339886: Patch

https://bugs.webkit.org/attachment.cgi?id=339886&action=review




--- Comment #3 from Saam Barati <sbarati at apple.com> ---
Comment on attachment 339886
  --> https://bugs.webkit.org/attachment.cgi?id=339886
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=339886&action=review

r=me

Seems reasonable. Can you add a test even if it's racy?

> Source/JavaScriptCore/bytecode/Watchpoint.cpp:101
> +    m_state = IsInvalidated; // Do after moving watchpoints to deferred to
transfer original.

I don't follow this comment here. Maybe:
"Do after moving watchpoints to deferredWatchpoints so deferredWatchpoints gets
our current state."

That said, we always know state will be IsWatched

> Source/JavaScriptCore/bytecode/Watchpoint.h:332
> +    void fireAll(VM& vm, DeferredWatchpointFire* deferred)
> +    {
> +	   if (isFat()) {
> +	       fat()->fireAll(vm, deferred);
> +	       return;
> +	   }
> +	   if (decodeState(m_data) == ClearWatchpoint)
> +	       return;
> +	   m_data = encodeState(IsInvalidated);
> +	   WTF::storeStoreFence();
> +    }

Maybe this can be templatized or abstracted since it's almost identical to
above fireAll?

> Source/JavaScriptCore/runtime/Structure.cpp:-204
> - 

please revert