[llvm] [Scalarizer][DirectX] support structs return types (PR #111569)

[Farzon Lotfi via llvm-commits]

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@@ -1195,7 +1261,7 @@ bool ScalarizerVisitor::finish() {
     if (!Op->use_empty()) {
       // The value is still needed, so recreate it using a series of
       // insertelements and/or shufflevectors.
-      Value *Res;
+      Value *Res = nullptr;
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farzonl wrote:

Reflexive change sorry. Uninitialized reads were a pattern I use to look for in security reviews. But looks like we never do anything but assign to Res so erroneous thinking on my part. Wasn't thinking this might be done this way to catch new conditions. 

https://github.com/llvm/llvm-project/pull/111569