[llvm-bugs] [Bug 34466] opt crashes with "opt -instcombine -adce -newgvn -gvn-hoist ": Assertion `DT->dominates(NewBB, OldBB) && "invalid path"' failed

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=34466

Jakub Kuderski <kubakuderski at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
           Assignee|unassignedbugs at nondot.org   |kubakuderski at gmail.com
             Status|NEW                         |RESOLVED

--- Comment #13 from Jakub Kuderski <kubakuderski at gmail.com> ---
I could not reproduce the bug with reduced test-cases with r314161 -- I tried
both the IR and c source version and don't get any ICEs. Only the original c
source triggers ICE for me.

-------------------------------------------------------------

This bug should be fixed by r314254. The problem was that the incremental
updater in ADCE would not invalidate DT's DFS numbers when it performed only
deletions (and no insertions). This must confuse some other transform and make
it misbehave, but I was not able to track it down precisely.

I think that a true 'fix' would be to make the DomTree verifier also check DFS
numbers if they are marked as valid.

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