On January 24, 2018 6:40:25 PM GMT+01:00, Jakub Jelinek <ja...@redhat.com> wrote: >On Wed, Jan 24, 2018 at 06:36:02PM +0100, Martin Jambor wrote: >> > I think there's already a set of attributes that prevent cloning >and >> > or are adjusted by the IPA param machinery. The Martins or Honza >> > should know better. >> >> I am not sure I understand the problem but if >> tree_versionable_function_p returns false, the local.versionable bit >is >> not set and no cloning for that function happens. >> >> If it is sufficient that IPA-CP and other IPA passes do not change >the >> function type in any way (in practice that they don't remove >> parameters), it is sufficient to clear the local.can_change_signature >> cgraph flag in compute_fn_summary() in ipa-fnsummary.c. That is how >we >> handle, or rather avoid handling, fnspec attributes. > >Well, "omp declare simd" is a part of the ABI just for the original >exported >functions, for everything else it is a pure optimization, but I'm not >sure >if we want to deoptimize e.g. callers of these functions outside of >loops >by disabling the signature changing cloning for those. For calls from >within OpenMP simd regions or other loops where we try hard to >vectorize >them, it might make sense not to change those callers, for callers from >other loops, a question.
Until we can distinguish the cases I think not changing the signature by default might be a good thing. Richard. > Jakub
