[PATCH] D152568: [InstCombine] Transform `(bitwise1 (bitwise2 (lshift1 X, C), C1), (lshift2 Y, C))`

[Noah Goldstein via Phabricator via llvm-commits]

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We can transform to:
`(lshift1 (bitwise1 (bitwise2 X, (inv_lshift1 C, C1), Y)), C1)`

Saving an instruction IFF:
`lshift1` is same opcode as `lshift2`
Either `bitwise1` and/or `bitwise2` is `and`.

Proof: https://alive2.llvm.org/ce/z/jejvxD

This is to help fix the regression caused in D151807 <https://reviews.llvm.org/D151807>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D152568

Files:
  llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
  llvm/test/Transforms/InstCombine/bitwise-and-shifts.ll
  llvm/test/Transforms/InstCombine/or-shifted-masks.ll

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