[all-commits] [llvm/llvm-project] 37afd9: Double check that passes correctly set their Modif...

[serge-sans-paille via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 37afd99c768b29c7df7c5f2eb645362fb61f9915
      https://github.com/llvm/llvm-project/commit/37afd99c768b29c7df7c5f2eb645362fb61f9915
  Author: serge-sans-paille <sguelton at redhat.com>
  Date:   2020-07-08 (Wed, 08 Jul 2020)

  Changed paths:
    M llvm/lib/IR/LegacyPassManager.cpp
    M llvm/unittests/IR/LegacyPassManagerTest.cpp

  Log Message:
  -----------
  Double check that passes correctly set their Modified status

The approach is simple: if a pass reports that it's not modifying a
Function/Module, compute a loose hash of that Function/Module and compare it
with the original one. If we report no change but there's a hash change, then we
have an error.

This approach misses a lot of change but it's not super intrusive and can
detect most of the simple mistakes.

Differential Revision: https://reviews.llvm.org/D80916