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

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev created this revision.
mkazantsev added reviewers: lebedev.ri, fhahn, reames, skatkov.
Herald added subscribers: llvm-commits, hiraditya.
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mkazantsev requested review of this revision.

We can sharpen the range of a AddRec if we know that it does not
self-wrap and know the symbolic iteration count in the loop. If we can
evaluate the value of AddRec on the last iteration and prove that at least
one its intermediate value lies between start and end, then no-wrap flag
allows us to conclude that all of them also lie between start and end. So
the estimate of range can be improved to union of ranges of start and end.


https://reviews.llvm.org/D89381

Files:
  llvm/include/llvm/Analysis/ScalarEvolution.h
  llvm/lib/Analysis/ScalarEvolution.cpp
  llvm/test/Analysis/ScalarEvolution/no-wrap-symbolic-becount.ll
  llvm/test/Transforms/IndVarSimplify/X86/eliminate-trunc.ll
  llvm/test/Transforms/IndVarSimplify/promote-iv-to-eliminate-casts.ll
  llvm/test/Transforms/IndVarSimplify/widen-loop-comp.ll

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