On 03/04/2020 13:27, Richard Sandiford wrote: > "Richard Earnshaw (lists)" <richard.earns...@arm.com> writes: >> On 02/04/2020 19:53, Richard Henderson via Gcc-patches wrote: >>> This is attacking case 3 of PR 94174. >>> >>> In v2, I unify the various subtract-with-borrow and add-with-carry >>> patterns that also output flags with unspecs. As suggested by >>> Richard Sandiford during review of v1. It does seem cleaner. >>> >> >> Really? I didn't need to use any unspecs for the Arm version of this. >> >> R. > > See https://gcc.gnu.org/pipermail/gcc-patches/2020-April/543063.html > (including quoted context) for how we got here. > > The same problem affects the existing aarch64 patterns like > *usub<GPI:mode>3_carryinC. Although that pattern avoids unspecs, > the compare:CC doesn't seem to be correct. > > Richard >
But I don't think you can use ANY_EXTEND in these comparisons. It doesn't describe what the instruction does, since the instruction does not really extend the values first. I would really expect this patch series to be pretty much a dual of this series that I posted last year for Arm. https://gcc.gnu.org/pipermail/gcc-patches/2019-October/532180.html R.
