Messages in this thread | | | Subject | Re: [PATCH 1/1] vsprintf: optimize decimal conversion (again) | Date | Tue, 27 Mar 2012 19:12:51 +0200 | From | "Michal Nazarewicz" <> |
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On Mon, 26 Mar 2012 22:20:52 +0200, H. Peter Anvin <hpa@zytor.com> wrote:
> On 03/26/2012 01:13 PM, Andrew Morton wrote: >> On Mon, 26 Mar 2012 21:56:38 +0200 >> Denys Vlasenko <vda.linux@googlemail.com> wrote: >> >>>>> +#if BITS_PER_LONG != 32 || (~(0ULL)>>1) != ((1ULL<<63)-1) >>>> >>>> What's this for? >>> >>> The second check should be just BITS_PER_LONG_LONG != 64, >>> but we don't have BITS_PER_LONG_LONG. >> >> So let's add BITS_PER_LONG_LONG rather than hacking around its absence! > > First of all, the #if is wrong: the preprocessor doesn't support data > types and does all arithmetic at (u)intmax_t precision.
Maybe a regular “if” instead of macro would suffice here? Compiler should be smart enough to optimise out the dead path.
> As far as BITS_PER_LONG_LONG, there are tons of places in the kernel > which already require that long long is exactly 64 bits. That may or > may not be a good thing, but for right now one could simply: > > #define BITS_PER_LONG_LONG 64
-- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michał “mina86” Nazarewicz (o o) ooo +----<email/xmpp: mpn@google.com>--------------ooO--(_)--Ooo-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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