[llvm] [DemandedBits] Support non-constant shift amounts (PR #148880)

[Panagiotis Karouzakis via llvm-commits]

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@@ -76,6 +76,19 @@ void DemandedBits::determineLiveOperandBits(
           computeKnownBits(V2, Known2, DL, &AC, UserI, &DT);
         }
       };
+  auto GetShiftedRange = [&](unsigned Min, unsigned Max, bool ShiftLeft) {
+    using ShiftFn = APInt (APInt::*)(unsigned) const;
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karouzakisp wrote:

Yes, but I think we need either std::mem_fn or lambda functions for the binding. 

I think this is the simplest way to express it

https://github.com/llvm/llvm-project/pull/148880