[all-commits] [llvm/llvm-project] 43d48e: [PowerPC] Add option to disable perfect shuffle

[Qiu Chaofan via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 43d48ed22029e92d88c608c55c6c42490ec3a243
      https://github.com/llvm/llvm-project/commit/43d48ed22029e92d88c608c55c6c42490ec3a243
  Author: Qiu Chaofan <qiucofan at cn.ibm.com>
  Date:   2022-02-21 (Mon, 21 Feb 2022)

  Changed paths:
    M llvm/lib/Target/PowerPC/PPCISelLowering.cpp

  Log Message:
  -----------
  [PowerPC] Add option to disable perfect shuffle

Perfect shuffle was introduced into PowerPC backend years ago, and only
available in big-endian subtargets. This optimization has good effects
in simple cases, but brings serious negative impact in large programs
with many shuffle instructions sharing the same mask.

Here introduces a temporary backend hidden option to control it until we
implemented better way to fix the gap in vectorshuffle decomposition.

Reviewed By: jsji

Differential Revision: https://reviews.llvm.org/D120072