[NFC][CodeGen][CFI] Extract CreateMetadataIdentifierForFnType (#158189)

For #158193

Author: vitalybuka

clang/lib/CodeGen/CGExpr.cpp

@@ -6496,11 +6496,8 @@ RValue CodeGenFunction::EmitCall(QualType CalleeType,
     SanitizerDebugLocation SanScope(this, {CheckOrdinal}, CheckHandler);
     EmitSanitizerStatReport(llvm::SanStat_CFI_ICall);
 
-    llvm::Metadata *MD;
-    if (CGM.getCodeGenOpts().SanitizeCfiICallGeneralizePointers)
-      MD = CGM.CreateMetadataIdentifierGeneralized(QualType(FnType, 0));
-    else
-      MD = CGM.CreateMetadataIdentifierForType(QualType(FnType, 0));
+    llvm::Metadata *MD =
+        CGM.CreateMetadataIdentifierForFnType(QualType(FnType, 0));
 
     llvm::Value *TypeId = llvm::MetadataAsValue::get(getLLVMContext(), MD);
 

clang/lib/CodeGen/CodeGenModule.cpp

@@ -7934,6 +7934,13 @@ CodeGenModule::CreateMetadataIdentifierImpl(QualType T, MetadataTypeMap &Map,
   return InternalId;
 }
 
+llvm::Metadata *CodeGenModule::CreateMetadataIdentifierForFnType(QualType T) {
+  assert(isa<FunctionType>(T));
+  if (getCodeGenOpts().SanitizeCfiICallGeneralizePointers)
+    return CreateMetadataIdentifierGeneralized(T);
+  return CreateMetadataIdentifierForType(T);
+}
+
 llvm::Metadata *CodeGenModule::CreateMetadataIdentifierForType(QualType T) {
   return CreateMetadataIdentifierImpl(T, MetadataIdMap, "");
 }

clang/lib/CodeGen/CodeGenModule.h

@@ -1623,6 +1623,9 @@ class CodeGenModule : public CodeGenTypeCache {
   /// Generate a KCFI type identifier for T.
   llvm::ConstantInt *CreateKCFITypeId(QualType T, StringRef Salt);
 
+  /// Create a metadata identifier for the given function type.
+  llvm::Metadata *CreateMetadataIdentifierForFnType(QualType T);
+
   /// Create a metadata identifier for the given type. This may either be an
   /// MDString (for external identifiers) or a distinct unnamed MDNode (for
   /// internal identifiers).