[PATCH] D74228: [PatternMatch] Match XOR variant of unsigned-add overflow check.

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

In D74228#1870646 <https://reviews.llvm.org/D74228#1870646>, @fhahn wrote:

> So should I prepare a set of patches for the improved target hook? Or SelDag? I would slightly prefer CGP for that, also with GlobalISel in mind and that's were we already do the expansion for similar cases.


It's an odd argument to add to CGP if we are using GlobalISel for codegen. CGP is intended to be a SDAG-only hack because of the basic block limitation there. Without the block limitation, we should favor doing transforms in the "official" codegen form. So IIUC, GISel should never use CGP. Eventually, the GISel path must re-implement the combines in both CGP and SDAG to become perf-equivalent. So I'd favor SDAG on this patch unless there's evidence that the 'not' and 'cmp' are not always in the same block?
@nikic or others - does that match your expectations?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D74228/new/

https://reviews.llvm.org/D74228