[webkit-reviews] review requested: [Bug 181599] PoisonedWriteBarrier : [Attachment 331235] patch

[bugzilla-daemon at webkit.org]

JF Bastien <jfbastien at apple.com> has asked  for review:
Bug 181599: PoisonedWriteBarrier
https://bugs.webkit.org/show_bug.cgi?id=181599

Attachment 331235: patch

https://bugs.webkit.org/attachment.cgi?id=331235&action=review




--- Comment #8 from JF Bastien <jfbastien at apple.com> ---
Created attachment 331235

  --> https://bugs.webkit.org/attachment.cgi?id=331235&action=review

patch

> > Source/JavaScriptCore/runtime/WriteBarrier.h:113
> > +	     validateCell<T>(Traits::unwrap(cell));
> > +	     return Traits::unwrap(cell);
> 
> I suggest pre-caching the unwrapped pointer:
>     T* resultCell = Traits::unwrap(cell);
>     validateCell<T>(resultCell);
>     return resultCell;
> 
> > Source/JavaScriptCore/runtime/WriteBarrier.h:121
> > +	     validateCell(Traits::unwrap(cell));
> > +	     return Traits::unwrap(cell);
> 
> Ditto.  precache?

Done x 2.

> > Source/JavaScriptCore/wasm/js/WasmToJS.cpp:482
> > +	
jit.move(CCallHelpers::TrustedImm64(JSWebAssemblyInstance::PoisonedBarrier<WebA
ssemblyToJSCallee>::poison), importJSCellGPRReg);
> 
> It is wrong to assume that importJSCellGPRReg (i.e. GPRInfo::regT0) !==
> GPRInfo::argumentGPR0.  In fact, on ARM64 (and most other architectures),
> they are the same.  You're just lucky that they aren't the same on x86_64
> here.  Please fix.

Nice, good catch! I hadn't looked at all the ISAs. Fixed now.