[clang] [Clang] Update `__builtin_masked_load` to accept passthrough argument (PR #155652)

[Erich Keane via cfe-commits]

================
@@ -2295,6 +2295,15 @@ static ExprResult BuiltinMaskedLoad(Sema &S, CallExpr *TheCall) {
   QualType PointeeTy = PtrTy->getPointeeType();
   const VectorType *MaskVecTy = MaskTy->getAs<VectorType>();
   const VectorType *DataVecTy = PointeeTy->getAs<VectorType>();
+
+  if (TheCall->getNumArgs() == 3) {
+    Expr *PassThruArg = TheCall->getArg(2);
+    QualType PassThruTy = PassThruArg->getType();
+    if (!S.Context.hasSameType(PassThruTy, PointeeTy))
+      return S.Diag(PtrArg->getExprLoc(), diag::err_vec_masked_load_store_ptr)
+             << /* third */ 3 << PointeeTy;
----------------
erichkeane wrote:

```suggestion
             << /* third argument=*/ 3 << PointeeTy;
```

https://github.com/llvm/llvm-project/pull/155652