[PATCH] D106532: [ARM] Attempt to distribute reductions

[Dave Green via Phabricator via llvm-commits]

dmgreen created this revision.
dmgreen added reviewers: samtebbs, SjoerdMeijer, NickGuy, ostannard, simon_tatham.
Herald added subscribers: danielkiss, hiraditya, kristof.beyls.
dmgreen requested review of this revision.
Herald added a project: LLVM.

This adds a combine for adds of reductions, distributing them so that they occur sequentially to enable better use of accumulating VADDVA instructions. It combines:

  add(X, add(vecreduce(Y), vecreduce(Z))) -> add(add(X, vecreduce(Y)), vecreduce(Z))

and

  add(add(A, reduce(B)), add(C, reduce(D))) -> add(add(add(A, C), reduce(B)), reduce(D))

These together distribute the add's so that more reductions can be selected to VADDVA.


https://reviews.llvm.org/D106532

Files:
  llvm/lib/Target/ARM/ARMISelLowering.cpp
  llvm/test/CodeGen/Thumb2/mve-vaddv.ll
  llvm/test/CodeGen/Thumb2/mve-vecreduce-slp.ll

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