[PATCH] D63629: [JumpThreading][PR42085] Fold constant TIs before calculating LoopHeaders

[Brian Rzycki via Phabricator via llvm-commits]

brzycki added a comment.

In D63629#1557870 <https://reviews.llvm.org/D63629#1557870>, @xbolva00 wrote:

> Yes, FindFunctionBackedges. But not sure if it would not introduce new regressions..


Yes, that's my concern as well. The way that JumpThreading uses `FindFunctionBackedges()` is a bit unusual as a proxy for detecting loop headers without dominators or loopinfo. I'm unsure if alternate forms of loopheader detection using this analysis can remove the need to eliminate these invalid edges in `F`. The core problem of this IR shape is JT's analysis fails to detect the true loop headers and eventually we thread across one.


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