[llvm] [InstCombine] Infer exact for lshr by cttz (PR #136696)

[Nikita Popov via llvm-commits]

=?utf-8?b?6buD5ZyL5bqt?= <we3223 at gmail.com>,
=?utf-8?b?6buD5ZyL5bqt?= <we3223 at gmail.com>
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In-Reply-To: <llvm.org/llvm/llvm-project/pull/136696 at github.com>


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@@ -994,6 +994,12 @@ static bool setShiftFlags(BinaryOperator &I, const SimplifyQuery &Q) {
       I.setIsExact();
       return true;
     }
+    // Infer 'exact' flag if shift amount is cttz(x, 1) on the same operand.
----------------
nikic wrote:

```suggestion
    // Infer 'exact' flag if shift amount is cttz(x) on the same operand.
```

https://github.com/llvm/llvm-project/pull/136696