[all-commits] [llvm/llvm-project] 1ffea9: [indvars] Support known positive extends in getExt...

[Philip Reames via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1ffea97ffdbe4148db7c6db4638d2ec56234c502
      https://github.com/llvm/llvm-project/commit/1ffea97ffdbe4148db7c6db4638d2ec56234c502
  Author: Philip Reames <preames at rivosinc.com>
  Date:   2023-11-03 (Fri, 03 Nov 2023)

  Changed paths:
    M llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
    M llvm/test/Transforms/IndVarSimplify/promote-iv-to-eliminate-casts.ll
    M llvm/test/Transforms/IndVarSimplify/widen-nonnegative.ll
    M llvm/test/Transforms/LoopFlatten/widen-iv.ll

  Log Message:
  -----------
  [indvars] Support known positive extends in getExtendedOperandRecurrence (#70990)

IndVars has the existing notion of a narrow definition which is known to
positive and thus both sign and zero extension kinds are actually the
same operations. There's existing logic for forming a SCEV based on the
extension kind and the no-wrap flags. This change extends that logic to
form the opposite extension kind for a positive def if doing so is
allowed by the flags. Note that we already do something analogous for
the getWideRecurrence case as well.