[all-commits] [llvm/llvm-project] 8e2a0e: [AArch64] Break up larger shuffle-masks into legal...

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 8e2a0e61f53887c98219cf8e8057f53bf507cd9b
      https://github.com/llvm/llvm-project/commit/8e2a0e61f53887c98219cf8e8057f53bf507cd9b
  Author: David Green <david.green at arm.com>
  Date:   2022-04-27 (Wed, 27 Apr 2022)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
    M llvm/test/Analysis/CostModel/AArch64/shuffle-other.ll

  Log Message:
  -----------
  [AArch64] Break up larger shuffle-masks into legal sizes in getShuffleCost

Given a larger-than-legal shuffle mask, the final codegen will split
into multiple sub-vectors. This attempts to model that in
AArch64TTIImpl::getShuffleCost, splitting masks up according to the size
of the legalized vectors. If the sub-masks have at most 2 input sources
we can call getShuffleCost on them and sum the costs, to get a more
accurate final cost for the entire shuffle. The call to
improveShuffleKindFromMask helps to improve the shuffle kind for the
sub-mask cost call.

Differential Revision: https://reviews.llvm.org/D123414