[PATCH] D146813: [LICM] Reassociate GEPs to allow hoisting

[Nikita Popov via Phabricator via llvm-commits]

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Reassociate `gep (gep ptr, idx1), idx2` to `gep (gep ptr, idx2), idx1` if this would make the inner GEP loop invariant and thus hoistable.

This is intended to replace an InstCombine fold that does this (in https://github.com/llvm/llvm-project/blob/04f61fb73dc6a994ab267d431f2fdaedc67430ff/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp#L2006). The problem with the InstCombine fold is that LoopInfo is an optional dependency, so it is not performed reliably.


https://reviews.llvm.org/D146813

Files:
  llvm/lib/Transforms/Scalar/LICM.cpp
  llvm/test/Transforms/LICM/gep-reassociate.ll

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