[PATCH] D89381: [SCEV] Use nw flag and symbolic iteration count to sharpen ranges of AddRecs

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev added inline comments.


================
Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:5744
+  };
+  if (isKnownPositive(Step) && isKnownPredicate(LEPred, Start, End)) {
+    if (!ProveBetween(LEPred))
----------------
efriedma wrote:
> At first I wasn't sure what `isKnownPredicate(LEPred, Start, End))` was checking, but then I figured out it's accounting for the possibility of crossing INT_MAX/UINT_MAX, since nw doesn't exclude that.  I think an alternate way of satisfying this condition would be to check for nsw/nuw.
> 
> 
`nuw/nsw` checks should be, in different ways, already incorporated inside of `isKnownPredicate`.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D89381/new/

https://reviews.llvm.org/D89381