[all-commits] [llvm/llvm-project] 1d178d: [Scheduling] Fall back to the fast cluster algorit...

[QingShan Zhang via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 1d178d600af77599b398930a640991c9c965a47c
      https://github.com/llvm/llvm-project/commit/1d178d600af77599b398930a640991c9c965a47c
  Author: QingShan Zhang <qshanz at cn.ibm.com>
  Date:   2020-11-02 (Mon, 02 Nov 2020)

  Changed paths:
    M llvm/lib/CodeGen/MachineScheduler.cpp
    M llvm/test/CodeGen/AArch64/aarch64-stp-cluster.ll

  Log Message:
  -----------
  [Scheduling] Fall back to the fast cluster algorithm if the DAG is too complex

We have added a new load/store cluster algorithm in D85517. However, AArch64 see
some compiling deg with the new algorithm as the IsReachable() is not cheap if
the DAG is complex. O(M+N) See https://bugs.llvm.org/show_bug.cgi?id=47966
So, this patch added a heuristic to switch to old cluster algorithm if the DAG is too complex.

Reviewed By: Owen Anderson

Differential Revision: https://reviews.llvm.org/D90144