[PATCH] D68916: [ARM] Accept ldrb.w mnemonic for certain addressing modes (PR43382)

[Sander de Smalen via Phabricator via llvm-commits]

sdesmalen added a comment.

In D68916#1741305 <https://reviews.llvm.org/D68916#1741305>, @efriedma wrote:

> Do you have a reply to the following?
>
> In D68916#1708799 <https://reviews.llvm.org/D68916#1708799>, @efriedma wrote:
>
> > It looks like the normal instruction patterns resolve the issue using "Constraints", to specify "Rn_wb".  I guess that isn't possible for aliases, though, at least at the moment?
>


>From my discussion with @chill today, that seems to be the issue indeed. TableGen doesn't use the `$addr.base = $Rn_wb` constraint from the instruction to materialize the second output register for the InstAliases. This is probably best fixed in TableGen itself, but having seen some of that code I can appreciate there is a tradeoff here whether or not to go the `AsmMatchConverter` route.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D68916/new/

https://reviews.llvm.org/D68916