[llvm] r277690 - Revert "GVN-hoist: enable by default" & "Make GVN Hoisting obey optnone/bisect."

[Daniel Berlin via llvm-commits]

I can't get gvn-hoist to fail on this testcase no matter what i do, even on
darwin, with my own built clang at the same rev.


On Thu, Aug 4, 2016 at 10:10 AM, Bruno Cardoso Lopes <
bruno.cardoso at gmail.com> wrote:

> Hi Sebastian,
>
> Attached the reproducer with a preprocessed and bitcode testcase. Let
> me know if you need any help.
>
> On Thu, Aug 4, 2016 at 7:30 AM, Sebastian Pop <sebpop at gmail.com> wrote:
> > I will need a preprocessed file or a reduced testcase:
> > with the same cmake options as the bot, I was not able to see the fail
> > on x86_64-linux.
> > This was both when compiling with the system's gcc 5.4 and clang 3.8.
> > The fail may be related to the libc of the bot.
> >
> > Thanks,
> > Sebastian
> >
> > On Thu, Aug 4, 2016 at 8:10 AM, Sebastian Pop <sebpop at gmail.com> wrote:
> >> I am looking at this fail.
> >> I think I have enough information from the bot on how to reproduce the
> bug.
> >>
> >> On Thu, Aug 4, 2016 at 12:44 AM, Daniel Berlin <dberlin at dberlin.org>
> wrote:
> >>>
> >>>
> >>> On Wed, Aug 3, 2016 at 10:17 PM, Bruno Cardoso Lopes
> >>> <bruno.cardoso at gmail.com> wrote:
> >>>>
> >>>> Hi Daniel,
> >>>>
> >>>> On Wed, Aug 3, 2016 at 9:59 PM, Daniel Berlin <dberlin at dberlin.org>
> wrote:
> >>>> > so here's the super-curious question in my mind:
> >>>> >
> >>>> > Why didn't this break when this was enabled by default for like a
> month
> >>>> > before :)
> >>>>
> >>>> Not really sure why, I was not following the bots back then.
> >>>
> >>>
> >>> Yeah, it's semi-rhetorical. It's just really odd, and makes me think
> it's
> >>> related to one or more of the optimizations sebastian added (for
> example,
> >>> not recomputing DFS numbers).
> >>>
> >>>>
> >>>> Where
> >>>> there many changes following up the time it got off? Another
> >>>> possibility is that the bot could have been broken by another change
> >>>> that hid this?
> >>>> I can get my hands on the reproducer and send to you tomorrow if
> that's
> >>>> helpful.
> >>>>
> >>>
> >>> That would be really helpful.
> >>>
> >>>>
> >>>> -Bruno
> >>>>
> >>>> --
> >>>> Bruno Cardoso Lopes
> >>>> http://www.brunocardoso.cc
> >>>
> >>>
>
>
>
> --
> Bruno Cardoso Lopes
> http://www.brunocardoso.cc
>
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