Richard Biener <richard.guent...@gmail.com> writes: > On Mon, Dec 9, 2013 at 3:49 PM, Kenneth Zadeck <zad...@naturalbridge.com> > wrote: >> On 12/08/2013 05:35 AM, Richard Biener wrote: >>> >>> Richard Sandiford <rdsandif...@googlemail.com> wrote: >>>> >>>> Kenneth Zadeck <zad...@naturalbridge.com> writes: >>>>>>>>> >>>>>>>>> #define WIDE_INT_MAX_ELTS \ >>>>>>>>> - ((4 * MAX_BITSIZE_MODE_ANY_INT + HOST_BITS_PER_WIDE_INT - 1) \ >>>>>>>>> - / HOST_BITS_PER_WIDE_INT) >>>>>>>>> + (((MAX_BITSIZE_MODE_ANY_INT + HOST_BITS_PER_WIDE_INT - 1) \ >>>>>>>>> + / HOST_BITS_PER_WIDE_INT) + 1) >>>>>>>> >>>>>>>> I think this should be: >>>>>>>> >>>>>>>> (MAX_BITSIZE_MODE_ANY_INT / HOST_BITS_PER_WIDE_INT + 1) >>>>>>>> >>>>>>>> We only need an extra HWI if MAX_BITSIZE_MODE_ANY_INT is an exact >>>> >>>> multiple >>>>>>>> >>>>>>>> of HOST_BITS_PER_WIDE_INT. >>>>>>> >>>>>>> we will do this later when some other issues that Eric B raised are >>>> >>>> settled. >>>>>> >>>>>> I think you're talking about defining MAX_BITSIZE_MODE_ANY_INT as >>>>>> MAX_SIZE_MODE_ANY_INT * BITS_PER_UNIT, but that's orthogonal to the >>>>>> change above. IMO it doesn't make sense to both round up the >>>> >>>> division >>>>>> >>>>>> and also add 1 to the result. So I think we should make this change >>>>>> regardless of whatever follows. >>>>>> >>>>>> Looks good to me otherwise, thanks. >>>>>> >>>>>> Richard >>>>>> >>>>> so this one works the way you want. While it is true the the >>>> >>>> problems >>>>> >>>>> are disjoint, the solution will likely evolving change the same lines >>>> >>>> of >>>>> >>>>> source in two different ways. >>>> >>>> Well, if we're changing the definition of WIDE_INT_MAX_ELTS now (and we >>>> are) >>>> I think we should change it to something that makes sense. All we want >>>> is >>>> 1 extra bit. We don't need to round up the size and then add a whole >>>> HWI on top. Doing that will potentially pessimise targets that don't >>>> need anything beyond SImode. >>> >>> I agree. >>> >>> Richard. >> >> Done, ok to commit? > > + early examination of the target's mode file. The WIDE_INT_MAX_ELTS > + can accomodate at least 1 more bit so that unsigned numbers of that > + mode can be represented. Note that it is still possible to create > + fixed_wide_ints that have precisions greater than > + MAX_BITSIZE_MODE_ANY_INT. This can be useful when representing a > + double-width multiplication result, for example. */ > #define WIDE_INT_MAX_ELTS \ > - ((4 * MAX_BITSIZE_MODE_ANY_INT + HOST_BITS_PER_WIDE_INT - 1) \ > - / HOST_BITS_PER_WIDE_INT) > + (((MAX_BITSIZE_MODE_ANY_INT + HOST_BITS_PER_WIDE_INT - 1) \ > + / HOST_BITS_PER_WIDE_INT)) > + > > that doesn't reserve 1 more bit, it just rounds up. For one more bit you > need to add 1, so > > #define WIDE_INT_MAX_ELTS \ > + (((MAX_BITSIZE_MODE_ANY_INT + 1 + HOST_BITS_PER_WIDE_INT - 1) \ > + / HOST_BITS_PER_WIDE_INT)) > > no?
Or just: (MAX_BITSIZE_MODE_ANY_INT / HOST_BITS_PER_WIDE_INT + 1) as above. Richard
