[llvm] [IR][Instructions] Add `CallBase::getCalledFunctionName` helper (PR #127038)

[Matt Arsenault via llvm-commits]

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@@ -1345,6 +1345,16 @@ class CallBase : public Instruction {
     return nullptr;
   }
 
+  /// Shortcut to retrieving the name of the called function.
+  /// Returns std::nullopt, if the function cannot be found.
+  std::optional<StringRef> getCalledFunctionName() const {
+    Function *F = getCalledFunction();
+    if (F)
+      return F->getName();
+
+    return std::nullopt;
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arsenm wrote:

Which is the kind of failure you are trying to avoid needing to worry about? 

https://github.com/llvm/llvm-project/pull/127038