[llvm] [SDAG] Remove invalid check (NFC) (PR #146899)

[Matt Arsenault via llvm-commits]

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@@ -2518,7 +2518,7 @@ bool SelectionDAG::expandMultipleResultFPLibCall(
   unsigned NumResults = Node->getNumValues();
 
   const char *LCName = TLI->getLibcallName(LC);
-  if (!LC || !LCName)
+  if (!LCName)
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arsenm wrote:

It should include an explicit check against the invalid enum value (which I was also planning on moving to be 0). I have a pending patch which replaces most of this with checks against the LibcallImpl anyway 

https://github.com/llvm/llvm-project/pull/146899