[llvm] [Knowbits] Make nuw and nsw support in computeForAddSub optimal (PR #83382)

[Matt Arsenault via llvm-commits]

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@@ -564,7 +564,7 @@ void GISelKnownBits::computeKnownBitsImpl(Register R, KnownBits &Known,
     // right.
     KnownBits ExtKnown = KnownBits::makeConstant(APInt(BitWidth, BitWidth));
     KnownBits ShiftKnown = KnownBits::computeForAddSub(
-        /*Add*/ false, /*NSW*/ false, ExtKnown, WidthKnown);
+        /*Add*/ false, /*NSW*/ false, /* NUW*/ false, ExtKnown, WidthKnown);
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arsenm wrote:

```suggestion
        /*Add=*/ false, /*NSW=*/ false, /* NUW=*/ false, ExtKnown, WidthKnown);
```

https://github.com/llvm/llvm-project/pull/83382