[PATCH] D103147: [SelectionDAG][RISCV] Don't unroll 0/1-type bool VSELECTs

[Fraser Cormack via Phabricator via llvm-commits]

frasercrmck created this revision.
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This patch extends the cases in which the legalizer is able to express
VSELECT in terms of XOR/AND/OR. When dealing with a VSELECT between
boolean vector types, the mask itself is an all-ones or all-ones value
of the operand type, so a 0/1 boolean type behaves identically to a 0/-1
type.

This greatly helps RISC-V which relies on expansion for these nodes. It
also allows scalable-vector bool VSELECTs to use the default expansion,
where before it would crash in SelectionDAG::UnrollVectorOp.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D103147

Files:
  llvm/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-vselect.ll
  llvm/test/CodeGen/RISCV/rvv/vselect-mask.ll

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