[Bug tree-optimization/99101] optimization bug with -ffinite-loops

["251078896 at qq dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99101

--- Comment #3 from Rex <251078896 at qq dot com> ---
Dear Richard,

Your post is informative, but I can't follow them all. Where does those "<bb
2>", "basic block 14", "local count" come from? I'm very interested in this
kind of analysis (and tools). Could you give a hint to me? Thank you very
much.(In reply to Richard Biener from comment #2)
> And the heuristic in post-dom compute for infinite loops does not trigger
> because we do have an exit from the loop via EH which is noreturn and the
> processing
> of those CFG dead-ends first makes the loop reverse reachable but makes
> post-dominance "wrong".
> 
> Bin, you poked into this code recently as well, just in case you have any
> thoughts.
> 
> It might be that control dependence calculation should not use post
> dominators.

(In reply to Richard Biener from comment #2)
> And the heuristic in post-dom compute for infinite loops does not trigger
> because we do have an exit from the loop via EH which is noreturn and the
> processing
> of those CFG dead-ends first makes the loop reverse reachable but makes
> post-dominance "wrong".
> 
> Bin, you poked into this code recently as well, just in case you have any
> thoughts.
> 
> It might be that control dependence calculation should not use post
> dominators.