[llvm] [SDAG] Allow folding stack slots into sincos/frexp in more cases (PR #118117)

[Benjamin Maxwell via llvm-commits]

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@@ -2515,13 +2550,25 @@ bool SelectionDAG::expandMultipleResultFPLibCall(
     SDValue StoreValue = ST->getValue();
     unsigned ResNo = StoreValue.getResNo();
     Type *StoreType = StoreValue.getValueType().getTypeForEVT(Ctx);
-    if (CallRetResNo == ResNo || !ST->isSimple() ||
+    if (
+        // Ensure the store corresponds to an output pointer.
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MacDue wrote:

This is a (really) long if condition with multiple cases, I added comments to make the checks a little easier to follow.  

https://github.com/llvm/llvm-project/pull/118117