[Bug tree-optimization/61757] [4.10 Regression] genmodes failure with enable-checking

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61757

--- Comment #31 from rguenther at suse dot de <rguenther at suse dot de> ---
On July 14, 2014 8:57:31 PM CEST, law at redhat dot com
<gcc-bugzilla@gcc.gnu.org> wrote:
>https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61757
>
>Jeffrey A. Law <law at redhat dot com> changed:
>
>           What    |Removed                     |Added
>----------------------------------------------------------------------------
>                 CC|                            |law at redhat dot com
>
>--- Comment #30 from Jeffrey A. Law <law at redhat dot com> ---
>Richi -- in response to your question in c#26.  I'll be looking at a
>handful of
>DOM issues while in transit to the Cauldron.  That'll include another
>evaluation of whether or not we want to thread across back edges at
>all. 
>
>Invalidation of equivalences after traversing a backedge has been
>extremely
>problematical and I really question it's value in the real world.

For the case that triggered the miscompile it was useful. BTW, we do have
exactly all information necessary to invalidate with the dom walker unwind
stack. It just needs to be made somewhat more accessible, no?