[all-commits] [llvm/llvm-project] 75b3c3: [ARM] Disable UpperBound loop unrolling for MVE ta...

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 75b3c3d267bf49b9061db55c4527cfea9e62f77a
      https://github.com/llvm/llvm-project/commit/75b3c3d267bf49b9061db55c4527cfea9e62f77a
  Author: David Green <david.green at arm.com>
  Date:   2023-10-31 (Tue, 31 Oct 2023)

  Changed paths:
    M llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
    A llvm/test/Transforms/LoopUnroll/ARM/mve-upperbound.ll

  Log Message:
  -----------
  [ARM] Disable UpperBound loop unrolling for MVE tail predicated loops. (#69709)

For MVE tail predicated loops, better code can be generated by keeping
the loop whole than to unroll to an upper bound, which requires the
expansion of active lane masks that can be difficult to generate good
code for. This patch disables UpperBound unrolling when we find a
active_lane_mask in the loop.