[llvm-bugs] [Bug 37929] JumpThreading can take take several minutes on large functions

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=37929

Chijun Sima <simachijun at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |simachijun at gmail.com
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
 Fixed By Commit(s)|                            |r345353

--- Comment #1 from Chijun Sima <simachijun at gmail.com> ---
The issue exposed by the reproducer is that JumpThreading is trying to update
the dominator tree with a great number of updates, which causes poor
performance because the time complexity of the incremental updating algorithm
is proportional to the number of updates. 

Fixed in r345353 (https://reviews.llvm.org/rL345353) by reconstructing the
dominator tree in this case. The time used by Dominator Tree updating reduces
from 297s to 0.15s by the commit when compiling the reproducer with -O3 + UBSan
locally.

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