On September 25, 2020 6:21:23 PM EDT, Ryan Scott <ryan.gl.sc...@gmail.com> wrote: ... >However, I discovered recently that there are places where GHC *does* >use >unboxed tuples with arity greater than 62. For example, the >GHC.Prim.unpackInt8X64# [2] function returns an unboxed tuple of size >64. I >was confused for a while about how this was even possible, but I >realized >later than GHC only enforces the tuple size limit in expressions and >patterns [3]. Simply having a type signature with a large unboxed tuple >is >fine in and of itself, and since unpackInt8X64# is implemented as a >primop, >no large unboxed tuples are ever used in the "body" of the function. >(Indeed, primops don't have function bodies in the conventional sense.) >Other functions in GHC.Prim that use unboxed tuples of arity 64 include >unpackWord8X64# [4], packInt8X64# [5], and packWord8X64# [6]. > >But this makes me wonder: how on earth is it even possible to *use* >unpackInt8X64#?
I strongly suspect that the answer here is "you can't yet no one has noticed until now." The SIMD operations were essentially introduced as a technology preview and therefore never had proper tests added. Only a subset of these operations have any tests at all and I doubt anyone has attempted to use the 64-wide operations, which are rather specialized. Cheers, - Ben _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
