[all-commits] [llvm/llvm-project] 28d071: [DAGCombiner] Add combine avg from shifts (#113909)

[dnsampaio via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 28d071803387b6b5c2ba6bc8321aa8e35168167a
      https://github.com/llvm/llvm-project/commit/28d071803387b6b5c2ba6bc8321aa8e35168167a
  Author: dnsampaio <dnsampaio at gmail.com>
  Date:   2024-10-31 (Thu, 31 Oct 2024)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/lib/Target/ARM/ARMISelLowering.cpp
    M llvm/lib/Target/ARM/ARMInstrMVE.td
    M llvm/test/CodeGen/AArch64/avg.ll
    M llvm/test/CodeGen/AArch64/sve-hadd.ll

  Log Message:
  -----------
  [DAGCombiner] Add combine avg from shifts (#113909)

This teaches dagcombiner to fold:
`(asr (add nsw x, y), 1) -> (avgfloors x, y)`
`(lsr (add nuw x, y), 1) -> (avgflooru x, y)`

as well the combine them to a ceil variant:
`(avgfloors (add nsw x, y), 1) -> (avgceils x, y)` 
`(avgflooru (add nuw x, y), 1) -> (avgceilu x, y)`

iff valid for the target.

Removes some of the ARM MVE patterns that are now dead code.
It adds the avg opcodes to `IsQRMVEInstruction` as to preserve the
immediate splatting as before.



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