Also allow nocf_check only with -fsanitize=kcfi

Author: samitolvanen

clang/lib/Sema/SemaDeclAttr.cpp

@@ -2028,7 +2028,8 @@ static void handleStandardNoReturnAttr(Sema &S, Decl *D, const ParsedAttr &A) {
 }
 
 static void handleNoCfCheckAttr(Sema &S, Decl *D, const ParsedAttr &Attrs) {
-  if (!S.getLangOpts().CFProtectionBranch)
+  if (!S.getLangOpts().CFProtectionBranch &&
+      !S.getLangOpts().Sanitize.has(SanitizerKind::KCFI))
     S.Diag(Attrs.getLoc(), diag::warn_nocf_check_attribute_ignored);
   else
     handleSimpleAttribute<AnyX86NoCfCheckAttr>(S, D, Attrs);

clang/lib/Sema/SemaType.cpp

@@ -7936,7 +7936,8 @@ static bool handleFunctionTypeAttr(TypeProcessingState &state, ParsedAttr &attr,
   }
 
   if (attr.getKind() == ParsedAttr::AT_AnyX86NoCfCheck) {
-    if (!S.getLangOpts().CFProtectionBranch) {
+    if (!S.getLangOpts().CFProtectionBranch &&
+        !S.getLangOpts().Sanitize.has(SanitizerKind::KCFI)) {
       S.Diag(attr.getLoc(), diag::warn_nocf_check_attribute_ignored);
       attr.setInvalid();
       return true;

clang/test/Sema/attr-nocf_check.c

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -triple=x86_64-unknown-unknown -verify -fcf-protection=branch -fsyntax-only %s
+// RUN: %clang_cc1 -triple=x86_64-unknown-unknown -verify -fsanitize=kcfi -fsyntax-only %s
 
 // Function pointer definition.
 typedef void (*FuncPointerWithNoCfCheck)(void) __attribute__((nocf_check)); // no-warning