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

[Sander de Smalen via cfe-commits]

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@@ -7513,6 +7516,30 @@ 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.
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sdesmalen-arm wrote:

This comment reads a bit strange. What about:

```
// If the call requires a streaming-mode change and has scalable vector
// arguments or return values, then warn the user that the streaming and
// non-streaming vector lengths may be different.
```

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