[PATCH] D129734: [InstCombine] Canonicalize GEP of GEP by swapping constant-indexed GEP to the front

[William Junda Huang via Phabricator via llvm-commits]

huangjd created this revision.
huangjd added reviewers: davidxl, Carrot, nikic, spatel, reames, aeubanks.
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Alternative implementation to D125845 <https://reviews.llvm.org/D125845>. This way the code is cleaner as it will not interfere with LICM, because swapping constant GEP to the front will actually allow LICM to move it out of the loop. In addition, it is possibly more beneficial to codegen since evaluation of variable indices is pushed to the back, reducing potential pipeline stall on some architectures.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D129734

Files:
  llvm/lib/Transforms/InstCombine/InstCombineInternal.h
  llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
  llvm/test/Transforms/InstCombine/gep-canonicalize-constant-indices.ll
  llvm/test/Transforms/InstCombine/gep-combine-loop-invariant.ll
  llvm/test/Transforms/InstCombine/gep-merge-constant-indices.ll
  llvm/test/Transforms/InstCombine/opaque-ptr.ll
  llvm/test/Transforms/LoopVectorize/AArch64/vector-reverse-mask4.ll
  llvm/test/Transforms/LoopVectorize/interleaved-accesses.ll

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