* Re: + fls-change-parameter-to-unsigned-int.patch added to -mm tree
[not found] <20181105233301.KlgdF%akpm@linux-foundation.org>
@ 2018-11-06 15:14 ` Alexey Dobriyan
2018-11-06 15:44 ` Matthew Wilcox
0 siblings, 1 reply; 3+ messages in thread
From: Alexey Dobriyan @ 2018-11-06 15:14 UTC (permalink / raw)
To: willy; +Cc: linux-kernel, tglx, linux-arch
On Mon, Nov 05, 2018 at 03:33:01PM -0800, akpm@linux-foundation.org wrote:
> -static inline int fls(int x)
> +static inline int fls(unsigned int x)
> {
> - return fls64((unsigned int) x);
> + return fls64(x);
> }
Should it return "unsigned"? Logically it should.
I remember doing this and there was some code size increase :-(
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: + fls-change-parameter-to-unsigned-int.patch added to -mm tree
2018-11-06 15:14 ` + fls-change-parameter-to-unsigned-int.patch added to -mm tree Alexey Dobriyan
@ 2018-11-06 15:44 ` Matthew Wilcox
2018-11-06 17:01 ` Alexey Dobriyan
0 siblings, 1 reply; 3+ messages in thread
From: Matthew Wilcox @ 2018-11-06 15:44 UTC (permalink / raw)
To: Alexey Dobriyan; +Cc: linux-kernel, tglx, linux-arch
On Tue, Nov 06, 2018 at 06:14:44PM +0300, Alexey Dobriyan wrote:
> On Mon, Nov 05, 2018 at 03:33:01PM -0800, akpm@linux-foundation.org wrote:
>
> > -static inline int fls(int x)
> > +static inline int fls(unsigned int x)
> > {
> > - return fls64((unsigned int) x);
> > + return fls64(x);
> > }
>
> Should it return "unsigned"? Logically it should.
> I remember doing this and there was some code size increase :-(
Yes, it returns a number in the range [0-32], so it can absolutely
be unsigned. I'm kind of surprised it made any difference.
When you say "doing this", what did you try? unsigned fls(unsigned),
int fls(unsigned) or unsigned fls(int) ?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: + fls-change-parameter-to-unsigned-int.patch added to -mm tree
2018-11-06 15:44 ` Matthew Wilcox
@ 2018-11-06 17:01 ` Alexey Dobriyan
0 siblings, 0 replies; 3+ messages in thread
From: Alexey Dobriyan @ 2018-11-06 17:01 UTC (permalink / raw)
To: Matthew Wilcox; +Cc: linux-kernel, tglx, linux-arch
On Tue, Nov 06, 2018 at 07:44:37AM -0800, Matthew Wilcox wrote:
> On Tue, Nov 06, 2018 at 06:14:44PM +0300, Alexey Dobriyan wrote:
> > On Mon, Nov 05, 2018 at 03:33:01PM -0800, akpm@linux-foundation.org wrote:
> >
> > > -static inline int fls(int x)
> > > +static inline int fls(unsigned int x)
> > > {
> > > - return fls64((unsigned int) x);
> > > + return fls64(x);
> > > }
> >
> > Should it return "unsigned"? Logically it should.
> > I remember doing this and there was some code size increase :-(
>
> Yes, it returns a number in the range [0-32], so it can absolutely
> be unsigned. I'm kind of surprised it made any difference.
>
> When you say "doing this", what did you try? unsigned fls(unsigned),
> int fls(unsigned) or unsigned fls(int) ?
I did "unsigned fls()" with and without
if (rv > 32)
__builtin_unreachable();
but I didn't send anything because there was something erratic with code
generation.
^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] <20181105233301.KlgdF%akpm@linux-foundation.org>
2018-11-06 15:14 ` + fls-change-parameter-to-unsigned-int.patch added to -mm tree Alexey Dobriyan
2018-11-06 15:44 ` Matthew Wilcox
2018-11-06 17:01 ` Alexey Dobriyan
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