[IR][Instructions] Add CallBase::getCalledFunctionName helper

[tsymalla]

There's a lot of uses of getCalledFunction()->getName(), without ever checking if getCalledFunction() returns a nullptr. Add a new helper that returns an std::optional<StringRef>, that can be used to

• Avoid method chaining
• Have a more safe shortcut to get the callee name.

[llvmbot]

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Author: Thomas Symalla (tsymalla)

Changes

There's a lot of uses of getCalledFunction()->getName(), without ever checking if getCalledFunction() returns a nullptr. Add a new helper that returns an std::optional<StringRef>, that can be used to

• Avoid method chaining
• Have a more safe shortcut to get the callee name.

---

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

1 Files Affected:

• (modified) llvm/include/llvm/IR/InstrTypes.h (+10)

diff --git a/llvm/include/llvm/IR/InstrTypes.h b/llvm/include/llvm/IR/InstrTypes.h
index 90fe864d4ae71..c55a5a589fc53 100644
--- a/llvm/include/llvm/IR/InstrTypes.h
+++ b/llvm/include/llvm/IR/InstrTypes.h
@@ -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;
+  }
+
   /// Return true if the callsite is an indirect call.
   bool isIndirectCall() const;
 

[nikic]

If you're introducing a new helper API, please also update existing code that can make use of it.

[nikic]

Can we use an empty StringRef as the sentinel instead?

[tsymalla]

Technically, yes, but I think std::optional is a better fit, since using operator* on the return value would fail if no value is present.

[arsenm]

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

[nikic]

From a quick git grep "getCalledFunction()->getName()", it looks like there are a lot more places that could use this.

[tsymalla]

From a quick git grep "getCalledFunction()->getName()", it looks like there are a lot more places that could use this.

Yep. I wanted to see if the change is generally accepted at first, before changing all the code. I'll follow up with the remainder.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[tsymalla-AMD]

Sorry for the massive update. All callsites of getCalledFunction()->getName() should now be updated plus some extra changes.