Index: utils/TableGen/CodeGenDAGPatterns.cpp
===================================================================
--- utils/TableGen/CodeGenDAGPatterns.cpp
+++ utils/TableGen/CodeGenDAGPatterns.cpp
@@ -3220,7 +3220,7 @@
   // Scan all of the named values in the destination pattern, rejecting them if
   // they don't exist in the input pattern.
   for (const auto &Entry : DstNames) {
-    if (SrcNames[Entry.first].first == nullptr)
+    if (SrcNames.count(Entry.first) == 0)
       Pattern->error("Pattern has input without matching name in output: $" +
                      Entry.first);
   }
@@ -3228,8 +3228,8 @@
   // Scan all of the named values in the source pattern, rejecting them if the
   // name isn't used in the dest, and isn't used to tie two values together.
   for (const auto &Entry : SrcNames)
-    if (DstNames[Entry.first].first == nullptr &&
-        SrcNames[Entry.first].second == 1)
+    if (DstNames.count(Entry.first) == 0 &&
+        Entry.second.second == 1)
       Pattern->error("Pattern has dead named input: $" + Entry.first);
 
   PatternsToMatch.push_back(PTM);