[Bug rtl-optimization/66790] Invalid uninitialized register handling in REE

[ebotcazou at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66790

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |bonzini at gnu dot org,
                   |                            |zadeck at naturalbridge dot com

--- Comment #17 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> So I think there's three things to solve
>  - which problem should df_live be using, the one it says it's using or the
> one it actually does
>  - if it's the former, see if passes using the information need fixing
>  - if it's the latter and we need the new problem from this patch, ensure
> that it actually works correctly (initializing the out bitmaps to all ones,
> probably).

That sounds like a good plan.  On second thoughts, for the first point, maybe a
native speaker understands "an available definition on any path" as "an
available definition on one path, whatever it is", in which case the
description would be correct, albeit very confusing for non-native speakers. 
It would be good to have some insight from the DF maintainers here (CCed).

In any case, what's needed to fix the bug is "an available definition on every
path" and that's what Pierre-Marie's patch implements.  We're going to review
it in light of your remarks.