[llvm] [InstCombine] Add handling for (or (zext x), (shl (zext (ashr x, bw-1))), bw) -> (sext x) fold (PR #130316)

[Yingwei Zheng via llvm-commits]

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@@ -3122,13 +3122,12 @@ static Value *matchOrConcat(Instruction &Or, InstCombiner::BuilderTy &Builder) {
   // iX ext split: extending or(zext(x),shl(zext(y),bw/2) pattern
   // to consume sext/ashr: or(zext(sext(x)),shl(zext(sext(ashr(x))),bw/2)
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dtcxzyw wrote:

Comments need to be updated. BTW, `bw/2` should be changed to `bw-1`.


https://github.com/llvm/llvm-project/pull/130316