[all-commits] [llvm/llvm-project] 2bcc4d: [EarlyCSE] Explicitly require AAResultsWrapperPass.

[Florian Hahn via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 2bcc4db761768f1b7431237920f26360549ca268
      https://github.com/llvm/llvm-project/commit/2bcc4db761768f1b7431237920f26360549ca268
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2020-09-09 (Wed, 09 Sep 2020)

  Changed paths:
    M llvm/lib/Transforms/Scalar/EarlyCSE.cpp
    M llvm/lib/Transforms/Scalar/GVN.cpp
    A llvm/test/Transforms/EarlyCSE/reuse-preserved-memoryssa.ll

  Log Message:
  -----------
  [EarlyCSE] Explicitly require AAResultsWrapperPass.

The MemorySSAWrapperPass depends on AAResultsWrapperPass and if
MemorySSA is preserved but AAResultsWrapperPass is not, this could lead
to a crash when updating the last user of the MemorySSAWrapperPass.

Alternatively AAResultsWrapperPass could be marked preserved by GVN, but
I am not sure if that would be safe. I am not sure what is required in
order to preserve AAResultsWrapperPass. At the moment, it seems like a
couple of passes that do similar transforms to GVN are preserving it.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D87137