Bug 21295 – Replace ExecState with a call frame Register pointer

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Cameron Zwarich (cpst)]

Darin has been working on replacing ExecStates with a call frame Register pointer. This should be a small increase in function call performance.

[Darin Adler]

*** Bug 21214 has been marked as a duplicate of this bug. ***

[Darin Adler]

Created attachment 24036 [details]
some work in progress on getting fields out of ExecState

[Darin Adler]

Created attachment 24059 [details]
patch

[Geoffrey Garen]

Comment on attachment 24059 [details]
patch

+        ScopeChainNode(ScopeChainNode* next, JSObject* object, JSGlobalData* globalData, JSObject* globalThis)
+            : next(next)
+            , object(object)
+            , globalData(globalData)
+            , globalThis(globalThis)

I don't think you ended up using this, did you?

r=me -- should probably remove the ScopeChainNode change.

[Darin Adler]

(In reply to comment #4)
> (From update of attachment 24059 [details] [edit])
> +        ScopeChainNode(ScopeChainNode* next, JSObject* object, JSGlobalData*
> globalData, JSObject* globalThis)
> +            : next(next)
> +            , object(object)
> +            , globalData(globalData)
> +            , globalThis(globalThis)
> 
> I don't think you ended up using this, did you?

Yes, I did. That's still the way we get JSGlobalData faster in the more typical cases. It's possible we could roll that optimization back out because the really hot cases get it from the CTI. But all my performance testing has been with both mechanisms in place.

[Darin Adler]

(In reply to comment #5)
> Yes, I did. That's still the way we get JSGlobalData faster in the more typical
> cases.

More typical case means anyone who calls exec->globalData().

[Geoffrey Garen]

okeedokee!

[Darin Adler]

Comment on attachment 24059 [details]
patch

Clearing flag since I landed this.

http://trac.webkit.org/changeset/37257

[Darin Adler]

Created attachment 24090 [details]
patch

[Cameron Zwarich (cpst)]

Comment on attachment 24090 [details]
patch

r=me if you do the

#define exec CallFrame::create(r)

workaround for the local variable 'exec' in Machine::privateExecute() that we discussed, and then remove the use of 'exec' afterwards in a followup patch.

[Darin Adler]

http://trac.webkit.org/changeset/37297