[clang] [AArch64][SME] Warn when using a streaming builtin from a non-streaming function (PR #74064)

[Sander de Smalen via cfe-commits]

================
@@ -3168,11 +3168,70 @@ static void checkArmStreamingBuiltin(Sema &S, CallExpr *TheCall,
         << TheCall->getSourceRange() << "streaming compatible";
     return;
   }
+
+  if (FnType == ArmNonStreaming && BuiltinType == ArmStreaming) {
+    S.Diag(TheCall->getBeginLoc(), diag::warn_attribute_arm_sm_incompat_builtin)
+        << TheCall->getSourceRange() << "non-streaming";
+  }
+}
+
+static bool hasSMEZAState(const FunctionDecl *FD) {
+  if (FD->hasAttr<ArmNewZAAttr>())
+    return true;
+  if (const auto *T = FD->getType()->getAs<FunctionProtoType>())
+    if (T->getAArch64SMEAttributes() & FunctionType::SME_PStateZASharedMask)
+      return true;
+  return false;
+}
+
+static bool hasSMEZAState(unsigned BuiltinID) {
+  switch (BuiltinID) {
+  default:
+    return false;
+#define GET_SME_BUILTIN_HAS_ZA_STATE
+#include "clang/Basic/arm_sme_builtins_za_state.inc"
+#undef GET_SME_BUILTIN_HAS_ZA_STATE
+  }
+}
+
+bool Sema::CheckSMEBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
+  if (const FunctionDecl *FD = getCurFunctionDecl()) {
+    std::optional<ArmStreamingType> BuiltinType;
----------------
sdesmalen-arm wrote:

Why is this `std::optional<ArmStreamingType>` rather than `ArmStreamingType` ?
We could just set the `default:` case below to be `ArmNonStreaming`.

https://github.com/llvm/llvm-project/pull/74064