[PATCH] D111878: [SCEV] Allow non-overflowing binops when analyzing SCC

[Max Kazantsev via Phabricator via llvm-commits]

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First step of Phi SCC processing was proving that the range of phi-translated
set of external inputs is the union of these inputs.

As the 2nd step, we also allow nuw+nsw binary operations to be included into
the SCC. For such SCCs, not only Phi translation, but also arithmetics is possible,
so we cannot just say its range is union of inputs. However, both Phi translation
and nuw+nsw arithmetic operation preserve the following invariant:
"If all external inputs into this SCC were non-negative, the SCC itself is also non-negative".

In practice, it is very useful to prove range of chunked Phis, what is shown in tests.


https://reviews.llvm.org/D111878

Files:
  llvm/include/llvm/Analysis/ScalarEvolution.h
  llvm/lib/Analysis/ScalarEvolution.cpp
  llvm/test/Analysis/ScalarEvolution/outer_phi.ll
  llvm/test/Analysis/ScalarEvolution/pr49856.ll
  llvm/test/Analysis/ScalarEvolution/shift-recurrences.ll
  llvm/test/Analysis/ScalarEvolution/trivial-phis.ll
  llvm/test/Transforms/IndVarSimplify/outer_phi.ll

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