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    SubjectRe: [RFC][PATCH] introduce ptr_diff()
    Date
    David Howells <dhowells@redhat.com> writes:

    > Namhyung Kim <namhyung@gmail.com> wrote:
    >
    >> + if (is_power_of_2(__size)) \
    >> + __diff = (__addr1 - __addr2) >> ilog2(__size); \
    >> + else \
    >> + __diff = (__addr1 - __addr2) / __size; \
    >
    > You shouldn't need to do this. The compiler's optimiser should switch a
    > divide to a shift for a power-of-2 divisor.

    Only when the numerator is provably non-negative, which is certainly
    not the case here.

    --
    Måns Rullgård
    mans@mansr.com

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