[PATCH] D89281: [AArch64] Optimize lowering of 128-bit shifts by a variable

[Eli Friedman via Phabricator via llvm-commits]

efriedma created this revision.
efriedma added reviewers: dmgreen, RKSimon, SjoerdMeijer.
Herald added subscribers: danielkiss, hiraditya, kristof.beyls.
Herald added a project: LLVM.
efriedma requested review of this revision.

This takes advantage of the work that's been done on funnel shifts to make the implementation more readable.

I think we could shave off one more instruction in the funnel shift lowering: if we do the shifts in the opposite order, we can fold the shift by one into the orr.  Mostly orthogonal to this patch, though.

The implementation here isn't really target-specific; maybe we should be doing this in target-independent code?


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D89281

Files:
  llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
  llvm/test/CodeGen/AArch64/arm64-long-shift.ll

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