[llvm] [NFC] Reduce copies created of ConstantRange when getting ConstantRangeAttributes. (PR #90335)

[Nikita Popov via llvm-commits]

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@@ -71,8 +71,8 @@ class Argument final : public Value {
   FPClassTest getNoFPClass() const;
 
   /// If this argument has a range attribute, return the value range of the
-  /// argument. Otherwise, std::nullopt is returned.
-  std::optional<ConstantRange> getRange() const;
+  /// argument. Otherwise, nullptr is returned.
+  const ConstantRange *getRange() const;
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nikic wrote:

I'd prefer to leave this alone as well, to keep the APIs consistent.

https://github.com/llvm/llvm-project/pull/90335