Messages in this thread | | | From | Nick Desaulniers <> | Date | Wed, 5 May 2021 10:08:03 -0700 | Subject | Re: [PATCH] sched: Work around undefined behavior in sched class checking |
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On Wed, May 5, 2021 at 9:49 AM Andi Kleen <ak@linux.intel.com> wrote: > > > On 5/5/2021 9:41 AM, Nick Desaulniers wrote: > > On Wed, May 5, 2021 at 7:39 AM Andi Kleen <ak@linux.intel.com> wrote: > >>> Would you please provide a > >>> minimal test case? > >> You can only reproduce it with a LTO build because it needs knowledge > >> between different translation units for this specific case. > >> > >> But gcc will totally do the optimization even without LTO if it can > >> prove the same inside a single TU. > > It would be helpful to isolate a test case that doesn't rely on LTO, > > if possible. > > Like I wrote earlier we used to see it all the time in __pa_symbol > before it used RELOC_HIDE. I bet if you make RELOC_HIDE a nop you'll see > multiple instances. > > But not sure why you want a test case?
In general, when making a feature request to a compiler vendor, having a digestible snippet of code that demonstrates the problem goes a long way, much further than "clone this branch of my fork of this project and do a build and something goes wrong somewhere." We're too busy to do that, please take the time to isolate it before making such requests.
-- Thanks, ~Nick Desaulniers
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