[PATCH] D72436: [SCEV] get a more accurate range for AddRecExpr with nsw flag

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

Logic looks good to me. As @efriedma mentioned some extra tests would be good, especially for the different sign cases. The current test only covers negative start with negative step.



================
Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:5702
+              ConstantRange(SignedMin, APInt::getSignedMinValue(BitWidth)),
+              RangeType);
+      } else if (AllNonPos) {
----------------
It's possible to use `getNonEmpty()` to avoid the explicit check for signed-min / signed-max:

```
ConservativeResult = ConservativeResult.intersectWith(
    ConstantRange::getNonEmpty(getSignedRangeMin(AddRec->getStart()),
    APInt::getSignedMinValue(BitWidth)),
    RangeType);
```


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https://reviews.llvm.org/D72436