[PATCH] D73697: [LoopPredication] Optimize two exits case.

[Philip Reames via Phabricator via llvm-commits]

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If I'm reading the description and code correctly, you're basically trying to avoid generating the construct "a == umin(a, b)" right?  If so, what's the problem with generating that?  I would expect other transform passes (such as instcombine) to very happily rip that apart into the component pieces.  In fact, I see in instcombine the transform "foldICmpWithMinMax" which appears to do exactly that.  Why isn't that sufficient?

In fact, I took the predicate-exits.ll test file, ran it through loop-pred and then instcombine, and I see exactly the simplification expected.  This seems to result in the same form as your change, so why do we need the complexity here?


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