[PATCH] ARM: Homogeneous aggregates must be allocated to contiguous registers

[Renato Golin]

  Hi James,

  I'm not advocating for piling up more hacks, because, even though this request implements the feature in the back-end (thus freeing the front-end from architectural decisions regarding HA on ARM), it will not free the front-end from architectural decisions regarding HA on other platforms, or anything else in them for that matter.

  It'll also introduce code in the back-end to deal with an already existing hack (splitting structures into arguments), and once PCS helpers are in place, this code will be dead, as much as all other hacks in the front-end. Even though other front-ends can continue hacking the argument list as they are to deal with this PCS problem, new front-ends will still have to split them into arguments and maybe re-order them, which is still a hack.

  My only point is to keep hacks in the front-end until such a time when someone creates a PCS helper, rather than adding hacks all over the place. The former will make it easier to spot all the hacks until such day comes. This also seemed to be the general consensus for a number of years.

  But that's just a weak opinion, and I won't oppose to this change if other people feel it's the right way.

  cheers,
  --renato

http://llvm-reviews.chandlerc.com/D3082