[llvm] [SelectionDAG] Fold constant PARTIAL_REDUCE_SMLA/UMLA/SUMLA nodes (PR #210351)

[Simon Pilgrim via llvm-commits]

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@@ -7,10 +7,40 @@
 //===----------------------------------------------------------------------===//
 
 #include "SelectionDAGTestBase.h"
+#include "llvm/ADT/ArrayRef.h"
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RKSimon wrote:

if we can its better to get more extensive IR test coverage instead of unit tests

https://github.com/llvm/llvm-project/pull/210351