Messages in this thread | | | Date | Wed, 5 May 2021 17:34:54 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] sched: Work around undefined behavior in sched class checking |
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On Wed, May 05, 2021 at 07:34:42AM -0700, Andi Kleen wrote: > > > Use RELOC_HIDE to make this work. This hides the symbols from gcc, > > > so the optimizer won't make these assumption. I also split > > > the BUG_ONs in multiple. > > > > Urgh, that insanity again :/ Can't we pretty please get a GCC flag to > > disable that? > > Even if that was done (I could totally see the gcc people pushing back on this; > why should they add special flags just for Linux developers not understanding > ISO-C?)
I understand C fine, I just don't agree with it. I also want to explicitly define as much UB as is possible, because UB is just utter garbage.
So just like we do with -fwrapv and others, add more knobs that explictly define away UB. Less UB is more better. This being C it's unlikely we'll ever get to no UB, but we should damn well try :-)
> you would still need the fix for already shipping compilers.
Yes, there is that.
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