Bug 190317 – performJITMemcpy() should handle the case when the executable allocator is not initialized yet.

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

[Mark Lam]

When SeparatedWXHeaps is in use, jitWriteThunkGenerator() will call performJITMemcpy() to copy memory before the JIT fixed memory pool is initialize.  Before r236864, performJITMemcpy() would just do a memcpy in that case.  We need to restore the equivalent behavior.

<rdar://problem/45039398>

[Mark Lam]

Created attachment 351683 [details]
proposed patch.

[Saam Barati]

Comment on attachment 351683 [details]
proposed patch.

View in context: https://bugs.webkit.org/attachment.cgi?id=351683&action=review

> Source/JavaScriptCore/ChangeLog:10
> +        to copy memory before the JIT fixed memory pool is initialize.  Before r236864,

s/initialize/initialized

> Source/JavaScriptCore/ChangeLog:11
> +        performJITMemcpy() would just do a memcpy in that case.  We need to restore the

Why not just make it call memcpy? This feels like a roundabout way to solve that issue IMO

[Mark Lam]

(In reply to Saam Barati from comment #2)
> Comment on attachment 351683 [details]
> proposed patch.
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=351683&action=review
> 
> > Source/JavaScriptCore/ChangeLog:10
> > +        to copy memory before the JIT fixed memory pool is initialize.  Before r236864,
> 
> s/initialize/initialized

will fix.

> > Source/JavaScriptCore/ChangeLog:11
> > +        performJITMemcpy() would just do a memcpy in that case.  We need to restore the
> 
> Why not just make it call memcpy? This feels like a roundabout way to solve
> that issue IMO

Because jitWriteThunkGenerator() does not call performJITMemcpy() directly.  The call comes indirectly far below LinkBuffer::linkCode().

[Saam Barati]

Comment on attachment 351683 [details]
proposed patch.

r=me

[Mark Lam]

Thanks for the review.  Landed in r236880: <http://trac.webkit.org/r236880>.

[Mark Lam]

+ build fix landed in r236881: <http://trac.webkit.org/r236881>.