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

[Thomas Symalla via llvm-commits]

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

>From 065431f845b7e1954a3cc53070223ad5fe50512e Mon Sep 17 00:00:00 2001
From: Thomas Symalla <github at thomassymalla.de>
Date: Thu, 13 Feb 2025 10:53:43 +0100
Subject: [PATCH 1/2] Add CallBase::getCalledFunctionName

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.
---
 llvm/include/llvm/IR/InstrTypes.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

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;
 

>From 5d90a01141362b79c86e5b2c2eda05a86c0a9b65 Mon Sep 17 00:00:00 2001
From: Thomas Symalla <github at thomassymalla.de>
Date: Thu, 20 Feb 2025 09:29:48 +0100
Subject: [PATCH 2/2] Some refactorings to make use of the new helper.

`LibCallsShrinkWrap::perform`: This uses the potentially `nullptr` value
inside the loop in a debug statement before asserting on it. Move the
assertion outside `perform(CallInst &)`.

Some other arbitrary uses to replace `getCalledFunction()->getName()`.
---
 llvm/include/llvm/Analysis/VectorUtils.h         | 7 +++----
 llvm/lib/Transforms/Utils/InlineFunction.cpp     | 2 +-
 llvm/lib/Transforms/Utils/LibCallsShrinkWrap.cpp | 8 +++++---
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/llvm/include/llvm/Analysis/VectorUtils.h b/llvm/include/llvm/Analysis/VectorUtils.h
index f21594c557e0e..84ff40be22a4c 100644
--- a/llvm/include/llvm/Analysis/VectorUtils.h
+++ b/llvm/include/llvm/Analysis/VectorUtils.h
@@ -41,11 +41,10 @@ class VFDatabase {
   /// a vector Function ABI.
   static void getVFABIMappings(const CallInst &CI,
                                SmallVectorImpl<VFInfo> &Mappings) {
-    if (!CI.getCalledFunction())
+    const auto ScalarName = CI.getCalledFunctionName();
+    if (!ScalarName.has_value())
       return;
 
-    const StringRef ScalarName = CI.getCalledFunction()->getName();
-
     SmallVector<std::string, 8> ListOfStrings;
     // The check for the vector-function-abi-variant attribute is done when
     // retrieving the vector variant names here.
@@ -59,7 +58,7 @@ class VFDatabase {
       // ensuring that the variant described in the attribute has a
       // corresponding definition or declaration of the vector
       // function in the Module M.
-      if (Shape && (Shape->ScalarName == ScalarName)) {
+      if (Shape && (Shape->ScalarName == *ScalarName)) {
         assert(CI.getModule()->getFunction(Shape->VectorName) &&
                "Vector function is missing.");
         Mappings.push_back(*Shape);
diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index b92d8b16daad2..dbcfcf9700c10 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -1983,7 +1983,7 @@ static void trackInlinedStores(Function::iterator Start, Function::iterator End,
                                const CallBase &CB) {
   LLVM_DEBUG(errs() << "trackInlinedStores into "
                     << Start->getParent()->getName() << " from "
-                    << CB.getCalledFunction()->getName() << "\n");
+                    << *CB.getCalledFunctionName() << "\n");
   const DataLayout &DL = CB.getDataLayout();
   at::trackAssignments(Start, End, collectEscapedLocals(DL, CB), DL);
 }
diff --git a/llvm/lib/Transforms/Utils/LibCallsShrinkWrap.cpp b/llvm/lib/Transforms/Utils/LibCallsShrinkWrap.cpp
index 9fe655e548c22..8f50d06fe1663 100644
--- a/llvm/lib/Transforms/Utils/LibCallsShrinkWrap.cpp
+++ b/llvm/lib/Transforms/Utils/LibCallsShrinkWrap.cpp
@@ -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();
+      assert(CalleeName.has_value() &&
+             "perform() should apply to a non-empty callee");
+
+      LLVM_DEBUG(dbgs() << "CDCE calls: " << *CalleeName << "\n");
       if (perform(CI)) {
         Changed = true;
         LLVM_DEBUG(dbgs() << "Transformed\n");
@@ -487,7 +490,6 @@ void LibCallsShrinkWrap::shrinkWrapCI(CallInst *CI, Value *Cond) {
 bool LibCallsShrinkWrap::perform(CallInst *CI) {
   LibFunc Func;
   Function *Callee = CI->getCalledFunction();
-  assert(Callee && "perform() should apply to a non-empty callee");
   TLI.getLibFunc(*Callee, Func);
   assert(Func && "perform() is not expecting an empty function");