[PATCH] D107603: Fold (add (select lhs, rhs, cc, 0, y), x) -> (select lhs, rhs, cc, x, (add x, y))

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: asb, luismarques, khchen, arcbbb, evandro, jrtc27, frasercrmck, HsiangKai.
Herald added subscribers: StephenFan, apazos, sameer.abuasal, s.egerton, Jim, jocewei, PkmX, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, niosHD, sabuasal, simoncook, johnrusso, rbar, hiraditya.
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Similar for sub except sub isn't commutative.

Modify the existing and/or/xor folds to also work on ISD::SELECT
and not just RISCVISD::SELECT_CC. This is needed to make sure
we do this transform before type legalization turns i32 add/sub
into add/sub+sign_extend_inreg on RV64. If we don't do this before
that, the sign_extend_inreg will still be after the select.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D107603

Files:
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/test/CodeGen/RISCV/rv32zbs.ll
  llvm/test/CodeGen/RISCV/select-binop-identity.ll

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