[Webkit-unassigned] [Bug 159859] DFG CSE should know how to decay a MultiGetByOffset

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=159859

Saam Barati <sbarati at apple.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|webkit-unassigned at lists.web |sbarati at apple.com
                   |kit.org                     |

--- Comment #3 from Saam Barati <sbarati at apple.com> ---
(In reply to comment #2)
> (In reply to comment #1)
> > Is MultiGetByOffset not dominated by a StructureCheck the way GetByOffset is?
> 
> It's not dominated by a CheckStructure.  The MultiGetByOffset does its own
> structure check.
> 
> We want one switch statement that both checks that we have the structure we
> want and loads the value.  CheckStructure with multiple structures in its
> set will be a switch and MultiGetByOffset is always a switch (unless we
> failed to strength-reduce a one-case MultiGetByOffset), so that would be two
> switches.  That's not cool, because we can't guarantee that B3 will
> jump-thread or tail-dup two switches in a row.  So, MultiGetByOffset is its
> own check.

Gotcha. I'll work on fixing this.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.webkit.org/pipermail/webkit-unassigned/attachments/20161028/93716ec7/attachment-0001.html>