[all-commits] [llvm/llvm-project] e412ba: [MachineVerifier] add checks for INLINEASM_BR

[Nick Desaulniers via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e412bac9125a806d147f4f545dd057fac0b4a8f0
      https://github.com/llvm/llvm-project/commit/e412bac9125a806d147f4f545dd057fac0b4a8f0
  Author: Nick Desaulniers <ndesaulniers at google.com>
  Date:   2022-08-19 (Fri, 19 Aug 2022)

  Changed paths:
    M llvm/lib/CodeGen/MachineVerifier.cpp
    A llvm/test/MachineVerifier/verify-inlineasmbr.mir

  Log Message:
  -----------
  [MachineVerifier] add checks for INLINEASM_BR

Test for a case we observed after the initial implementation of D129997
landed, in which case we observed a crash while building the ppc64le
Linux kernel. In that case, we had one block with two exits, both to the
same successor. Removing one of the exits corrupted the
successor/predecessor lists.

So when we have an INLINEASM_BR, check a few things for each indirect
target:
1. that it exists.
2. that it is listed in our successors.
3. that its predecessor list contains the parent MBB of INLINEASM_BR.

This would have caught the regression discovered after D129997 landed,
after the pass that was problematic (early-tailduplication) rather than
getting a stack trace in a later pass (regalloc) that doesn't understand
the anomaly and crashes.

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D130290