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    SubjectRe: [PATCH 1/1] vsprintf: optimize decimal conversion (again)
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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

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