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

[Nikita Popov via llvm-commits]

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@@ -58,8 +58,11 @@ class LibCallsShrinkWrap : public InstVisitor<LibCallsShrinkWrap> {
   bool perform() {
     bool Changed = false;
     for (auto &CI : WorkList) {
-      LLVM_DEBUG(dbgs() << "CDCE calls: " << CI->getCalledFunction()->getName()
-                        << "\n");
+      auto CalleeName = CI->getCalledFunctionName();
----------------
nikic wrote:

```suggestion
      std::optional<StringRef> CalleeName = CI->getCalledFunctionName();
```

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