[clang] [Clang][AArch64] Warn when calling streaming/non-streaming about vect… (PR #79842)

[Sander de Smalen via cfe-commits]

================
@@ -7513,6 +7516,36 @@ void Sema::checkCall(NamedDecl *FDecl, const FunctionProtoType *Proto,
       }
     }
 
+    auto *CallerFD = dyn_cast<FunctionDecl>(CurContext);
+    bool IsCalleeStreaming =
+        (ExtInfo.AArch64SMEAttributes & FunctionType::SME_PStateSMEnabledMask);
+    bool IsCalleeStreamingCompatible =
+        (ExtInfo.AArch64SMEAttributes &
+         FunctionType::SME_PStateSMCompatibleMask);
+    bool IsBuiltin = (FD && FD->getBuiltinID());
+    AnyScalableArgsOrRet |= Proto->getReturnType()->isSizelessVectorType();
+
+    // If the caller is a function and the callee has a different
+    // non-compitable streaming attribute. If it passed any VL-based arguments
+    // or return VL-based value, then warn that the streaming and non-streaming
+    // vector lengths may be different.
+    if (CallerFD && Context.getTargetInfo().hasFeature("sme") && !IsBuiltin) {
----------------
sdesmalen-arm wrote:

```suggestion
    if (CallerFD && !IsBuiltin) {
```

It is valid to compile the following function without `+sme`:
```
void streaming_compatible_fn(svint32_t v, void (*foo)(svint32_t)) __arm_streaming_compatible {
  foo(v);
}
```

https://github.com/llvm/llvm-project/pull/79842