[llvm] [LVI] Learn value ranges from ctpop results (PR #121945)

[Nikita Popov via llvm-commits]

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@@ -1159,6 +1159,28 @@ getRangeViaSLT(CmpInst::Predicate Pred, APInt RHS,
   return std::nullopt;
 }
 
+/// Get value range for a "ctpop(Val) Pred RHS" condition.
+static ValueLatticeElement getValueFromICmpCtpop(ICmpInst::Predicate Pred,
+                                                 Value *RHS) {
+  unsigned BitWidth = RHS->getType()->getPrimitiveSizeInBits();
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nikic wrote:

getScalarSizeInBits() also works on vectors. It's not relevant here (unless maybe for select conditions?) but most code in LLVM handles scalars and vectors, so it's best to always use this API.

https://github.com/llvm/llvm-project/pull/121945