[PATCH] D40718: [LSR] Complexity tradeoff in GenerateReassociationsImpl

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev created this revision.

During its work, `GenerateReassociationsImpl` may end up trying calculating a sum
of a huge amount of huge SCEVs. Attempts to simplify them lead to huge compile
time problem. This patch applies a heuristic that limits simplification recursion depth
depending on number of arguments in this method to get an acceptible compile time
in corner cases while it should not affect most of real situations.


https://reviews.llvm.org/D40718

Files:
  lib/Transforms/Scalar/LoopStrengthReduce.cpp
  test/Transforms/LoopStrengthReduce/2017-12-01-long_compilation_corner_case.ll

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