Messages in this thread | | | Date | Tue, 27 Jul 2021 20:19:35 +1000 (AEST) | From | Finn Thain <> | Subject | Re: [PATCH 1/5] nubus: Simplify check in remove callback |
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On Tue, 27 Jul 2021, Geert Uytterhoeven wrote:
> On Tue, Jul 27, 2021 at 11:50 AM Finn Thain <fthain@linux-m68k.org> wrote: > > On Tue, 27 Jul 2021, Uwe Kleine-König wrote: > > > Apart from that, the compiler might already assume dev->driver being > > > non-NULL after to_nubus_driver(dev->driver) was called. > > > > I don't understand how a compiler can make that assumption. But then, > > I don't know why compilers do a lot of the things they do... > > It is one of those recent optimizations people have been complaining > about. Once you have dereferenced a pointer, compilers may remove all > further NULL-checks, assuming they can't happen, as the code would have > crashed anyway before due to the dereference.
But that's the point -- there is no dereference, just pointer arithmetic.
> Good luck running on bare metal with RAM at zero ;-)
Quite. | |