[PATCH] D109325: [ARM] Teach DemandedVectorElts about VMOVN lanes

Mon Sep 6 07:31:35 PDT 2021

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

The class of instructions that write to narrow top/bottom lanes only demand the even or odd elements of the input lanes. Which means that VMOVNT; VMOVNB demands no lanes from the original input. This teaches that to instcombine from the target hooks available through ARMTTIImpl.

https://reviews.llvm.org/D109325

Files:
  llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
  llvm/lib/Target/ARM/ARMTargetTransformInfo.h
  llvm/test/Transforms/InstCombine/ARM/mve-narrow.ll

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