Messages in this thread | | | From | Andy Shevchenko <> | Date | Mon, 15 Nov 2021 16:14:21 +0200 | Subject | Re: [PATCH v2 1/1] PCI: brcmstb: Use BIT() as __GENMASK() is for internal use only |
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On Mon, Nov 15, 2021 at 4:01 PM Robin Murphy <robin.murphy@arm.com> wrote: > On 2021-11-15 11:20, Andy Shevchenko wrote: > > Use BIT() as __GENMASK() is for internal use only. The rationale > > of switching to BIT() is to provide better generated code. The > > GENMASK() against non-constant numbers may produce an ugly assembler > > code. On contrary the BIT() is simply converted to corresponding shift > > operation. > > FWIW, If you care about code quality and want the compiler to do the > obvious thing, why not specify it as the obvious thing: > > u32 val = ~0 << msi->legacy_shift;
Obvious and buggy (from the C standard point of view)? :-)
> Personally I don't think that abusing BIT() in the context of setting > multiple bits is any better than abusing __GENMASK()...
No, BIT() is not abused here, but __GENMASK().
After all it's up to you, folks, consider that as a bug report.
-- With Best Regards, Andy Shevchenko
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