[PATCH] D157578: [DAGCombiner] Fold unsigned and/or of comparisons checking boundaries

[Noah Goldstein via Phabricator via llvm-commits]

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The boundary comparisons are of the pattern:

- Inclusive: `(and (icmp uge/ugt Val, Lo), (icmp ule/ult Val, Hi))`
- Exclusive: `(or (icmp ule/ult Val, Lo), (icmp uge/ugt Val, Hi))`

If we are able to prove `Hi u> Lo` (or sometimes only `Hi u>= Lo`), we
can often optimize these patterns to:

  `(icmp ule/ult (sub Val, Lo), (sub Hi, Lo))`

Proofs: https://alive2.llvm.org/ce/z/ZM3mXB


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D157578

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  llvm/test/CodeGen/AMDGPU/wave32.ll
  llvm/test/CodeGen/X86/icmp-in-unsigned-bounds.ll

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