[PATCH] D95551: [ARM] One-off identity shuffle

[Dave Green via Phabricator via llvm-commits]

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

A One-Off Identity mask is a shuffle that is mostly an identity mask from as single source but contains a single element out-of-place, either from a different vector or from another position in the same vector. As opposed to lowering this via a ARMISD::BUILD_VECTOR we can generate an extract/insert pair directly. Under ARM with individually accessible lane elements this often becomes a simple lane move.

This also alters the LowerVECTOR_SHUFFLEUsingMovs code to use v4f32 (not v4i32), a more natural type for lane moves.


https://reviews.llvm.org/D95551

Files:
  llvm/lib/Target/ARM/ARMISelLowering.cpp
  llvm/test/CodeGen/Thumb2/mve-shuffle.ll
  llvm/test/CodeGen/Thumb2/mve-vld3.ll
  llvm/test/CodeGen/Thumb2/mve-vst3.ll
  llvm/test/CodeGen/Thumb2/mve-vst4.ll

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