[PATCH] D119075: [DAGCombine][ARM] Custom lower smaller-than-legal MULH/AVG/ABD

[Dave Green via Phabricator via llvm-commits]

dmgreen updated this revision to Diff 483097.
dmgreen added a comment.
Herald added a subscriber: StephenFan.
Herald added a project: All.

Rebase the current patch. I would like to try and get something like this in if we can.

Unfortunately you seem to have given some pretty good reasons why the suggestions you made will not easily work. The lowering is target specific to uses the NVCast. I was attempting to make use of larger (potentially legal) hadds in combineShiftToAVG, but x86 wants to widen, not promote, and really wants to use the existing custom lowering it has. It would be better for Arm to use extend(hadd) than hadd(extend, extend), but as far as I understand that needs NVCast to be correct for BE.

Any suggestions on how to proceed?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D119075/new/

https://reviews.llvm.org/D119075

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
  llvm/lib/Target/ARM/ARMISelLowering.cpp
  llvm/test/CodeGen/Thumb2/mve-vabdus.ll
  llvm/test/CodeGen/Thumb2/mve-vhadd.ll
  llvm/test/CodeGen/Thumb2/mve-vmulh.ll

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