[PATCH] D50977: [TableGen] Examine entire subreg compositions to detect ambiguity

[Ulrich Weigand via Phabricator via llvm-commits]

uweigand added a comment.

In D50977#1309705 <https://reviews.llvm.org/D50977#1309705>, @uweigand wrote:

> If so, maybe we can fix this by swapping around the low and high subregs of all other register definitions, so that then subreg_h32 *always* maps to subreg_h32(subreg_h64)), and instead of explicit subreg_hh32 and subreg_hl32 we have rather subreg_lh32 and subreg_ll32 ?


To elaborate on this, I've now implemented this here: https://reviews.llvm.org/D54962  (with a more detailed explanation)

This does indeed eliminate the warning, without any changes in code generation.  (And it is a back-end only patch with no TableGen changes required.)

@kparzysz, does that make sense to you?


Repository:
  rL LLVM

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  https://reviews.llvm.org/D50977/new/

https://reviews.llvm.org/D50977