[llvm] [ConstantRange] Handle `Intrinsic::ctpop` (PR #68310)

[Nikita Popov via llvm-commits]

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@@ -1736,6 +1739,52 @@ ConstantRange ConstantRange::ctlz(bool ZeroIsPoison) const {
                      APInt(getBitWidth(), getUnsignedMin().countl_zero() + 1));
 }
 
+static ConstantRange getUnsignedPopCountRange(const APInt &Lower,
+                                              const APInt &Upper) {
+  assert(Lower.ule(Upper) && "Unexpected wrapped set.");
+  unsigned BitWidth = Lower.getBitWidth();
+  if (Lower == Upper)
+    return ConstantRange::getEmpty(BitWidth);
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nikic wrote:

Can we assert this case doesn't happen (possibly with the isUpperWrapped -> isWrappedSet suggestion below)?

https://github.com/llvm/llvm-project/pull/68310