[PATCH] D89381: [SCEV] Re-enable "Use nw flag and symbolic iteration count to sharpen ranges of AddRecs", attempt 3

[Nikita Popov via Phabricator via llvm-commits]

nikic accepted this revision.
nikic added a comment.
This revision is now accepted and ready to land.

LG for landing under the flag.

I already landed a couple of SCEV improvements on Sunday that improved compile-time (while also improving nowrap inference), and am still pursuing some more leads, so I hope we can drop the flag in the future.



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Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:5735
+  MaxBECount = getNoopOrZeroExtend(MaxBECount, AddRec->getType());
+  const SCEV *RangeWidth = getNegativeSCEV(getOne(AddRec->getType()));
+  const SCEV *StepAbs = getUMinExpr(Step, getNegativeSCEV(Step));
----------------
You can use the recently added getMinusOne() here.


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Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:5764
+  ConstantRange EndRange =
+      IsSigned ? getSignedRange(End) : getUnsignedRange(End);
+  ConstantRange RangeBetween = StartRange.unionWith(EndRange);
----------------
It might make more sense to use `getRangeRef(Start, SignHint)` and `getRangeRef(End, SignHint)` here, rather than going SignHint -> IsSigned -> SignHint.


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Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:5773
+      IsSigned ? RangeBetween.getLower().sge(RangeBetween.getUpper())
+               : RangeBetween.getLower().uge(RangeBetween.getUpper());
+  if (IsWrappingRange)
----------------
You can use isWrappedSet() and isSignWrappedSet() here (there are some special cases due to the half-open range).


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  https://reviews.llvm.org/D89381/new/

https://reviews.llvm.org/D89381