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09dcb16d13
Summary: Currently we always recompute LCSSA for outer loops after unrolling an inner loop. That leads to compile time problem when we have big loop nests, and we can solve it by avoiding unnecessary work. For instance, if w eonly do partial unrolling, we don't break LCSSA, so we don't need to rebuild it. Also, if all exits from the inner loop are inside the enclosing loop, then complete unrolling won't break LCSSA either. I replaced unconditional LCSSA recomputation with conditional recomputation + unconditional assert and added several tests, which were failing when I experimented with it. Soon I plan to follow up with a similar patch for recalculation of dominators tree. Reviewers: hfinkel, dexonsmith, bogner, joker.eph, chandlerc Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D14526 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253126 91177308-0d34-0410-b5e6-96231b3b80d8