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[InstCombine] Improve infinite loop detection

Authored by kuhar on Dec 18 2019, 1:00 PM.



This patch limits the default number of iterations performed by InstCombine. It also exposes a new option that allows to specify how many iterations is considered getting stuck in an infinite loop.

Based on experiments performed on real-world C++ programs, InstCombine seems to perform at most ~8-20 iterations, so treating 1000 iterations as an infinite loop seems like a safe choice. See D71145 for details.

The two limits can be specified via command line options.

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kuhar created this revision.Dec 18 2019, 1:00 PM
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spatel accepted this revision.Dec 20 2019, 9:57 AM


This revision is now accepted and ready to land.Dec 20 2019, 9:57 AM
This revision was automatically updated to reflect the committed changes.