[PATCH] D132771: [RISCV] Apply DeMorgan to (beqz (and/or (seteq), (xor Z, 1))) to remove the xor.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: reames, asb, luismarques, kito-cheng, frasercrmck.
Herald added subscribers: sunshaoce, VincentWu, luke957, StephenFan, vkmr, evandro, apazos, sameer.abuasal, s.egerton, Jim, benna, psnobl, jocewei, PkmX, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, jrtc27, shiva0217, niosHD, sabuasal, simoncook, johnrusso, rbar, hiraditya, arichardson.
Herald added a project: All.
craig.topper requested review of this revision.
Herald added subscribers: pcwang-thead, eopXD, MaskRay.
Herald added a project: LLVM.

We can rewrite to (bnez (or/and (setne), Z) is Z is 0/1.

Alternatively, we could canonicalize to (xor (or/and (setne), Z), 1)
even if there is no branch. The xor would not always get removed,
but it might enable other DeMorgan combines. I decided to be
conservative for this first patch and require the xor to be removed.

I have a couple other invertible setccs I will add in a follow up
patch.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132771

Files:
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/test/CodeGen/RISCV/setcc-logic.ll

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D132771.456061.patch
Type: text/x-patch
Size: 24274 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20220826/a455c6f8/attachment.bin>