[llvm] [SDAG] Honor signed arguments in floating point libcalls (PR #109134)

[Matt Arsenault via llvm-commits]

================
@@ -2205,7 +2205,13 @@ void SelectionDAGLegalize::ExpandFPLibCall(SDNode* Node,
     Results.push_back(Tmp.first);
     Results.push_back(Tmp.second);
   } else {
-    SDValue Tmp = ExpandLibCall(LC, Node, false).first;
+    bool IsSignedArgument = false;
+    switch (Node->getOpcode()) {
+    case ISD::FLDEXP:
+      IsSignedArgument = true;
+      break;
+    }
----------------
arsenm wrote:

```suggestion
    bool IsSignedArgument = Node->getOpcode() == ISD::FLDEXP;
```

https://github.com/llvm/llvm-project/pull/109134