[PATCH] D28629: [SCEV] Limit recursion depth of constant evolving

[Michael Liao via Phabricator via llvm-commits]

hliao added a comment.

iterative one is quite straight-forward but I don't see whether it's necessary. 'getConstantEvolvingPHI' is used in 'computeExitCountExhaustively' to evolve loop symbolically to check trip count in brute-force manner. I hardly to see it's widely applied. Ofc, let's check the statistics to see whether that's reasonable.

In addition, if ' getConstantEvolvingPHI' is re-written in iterative scheme, 'EvaluateExpression' needs to be re-written too as the later is predicated from the former and may push the out-of-stack into the later.


Repository:
  rL LLVM

https://reviews.llvm.org/D28629