[llvm-branch-commits] [clang] [clang] callee_type metadata for indirect calls (PR #117036)

[Paul Kirth via llvm-branch-commits]

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@@ -2869,9 +2870,23 @@ static void setLinkageForGV(llvm::GlobalValue *GV, const NamedDecl *ND) {
     GV->setLinkage(llvm::GlobalValue::ExternalWeakLinkage);
 }
 
+static bool hasExistingGeneralizedTypeMD(llvm::Function *F) {
+  llvm::MDNode *MD = F->getMetadata(llvm::LLVMContext::MD_type);
+  if (!MD)
+    return false;
+  return MD->hasGeneralizedMDString();
+}
+
 void CodeGenModule::createFunctionTypeMetadataForIcall(const FunctionDecl *FD,
                                                        llvm::Function *F) {
-  // Only if we are checking indirect calls.
+  if (CodeGenOpts.CallGraphSection && !hasExistingGeneralizedTypeMD(F) &&
+      (!F->hasLocalLinkage() ||
+       F->getFunction().hasAddressTaken(nullptr, /*IgnoreCallbackUses=*/true,
+                                        /*IgnoreAssumeLikeCalls=*/true,
+                                        /*IgnoreLLVMUsed=*/false)))
+    F->addTypeMetadata(0, CreateMetadataIdentifierGeneralized(FD->getType()));
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ilovepi wrote:

Doesn't this function just emit the type metadata if the function *could* be used as an indirect call target? The function name doesn't really communicate that though (at least to me). 

Based on that reading, I'd say limiting it to any non-local function (e.g. could be addr taken in another TU) and any local function that has its address taken makes sense for the call-graph use-case.

Or was there some other aspect that concerns you?

https://github.com/llvm/llvm-project/pull/117036