Index: llvm/lib/Passes/StandardInstrumentations.cpp
===================================================================
--- llvm/lib/Passes/StandardInstrumentations.cpp
+++ llvm/lib/Passes/StandardInstrumentations.cpp
@@ -647,13 +647,12 @@
 
   ChangedIRData::report(
       Before, After, [&](const ChangedFuncData *B, const ChangedFuncData *A) {
+        assert((B || A) && "Both functions cannot be missing.");
         ChangedFuncData Missing;
         if (!B)
           B = &Missing;
         else if (!A)
           A = &Missing;
-        assert(B != &Missing && A != &Missing &&
-               "Both functions cannot be missing.");
         handleFunctionCompare(Name, Prefix, PassID, true, *B, *A);
       });
 }
Index: llvm/test/Other/print-changed-diff.ll
===================================================================
--- /dev/null
+++ llvm/test/Other/print-changed-diff.ll
@@ -0,0 +1,15 @@
+; D107989 This triggered an assert
+
+; RUN: opt  -passes=globalopt < %s -disable-output -print-changed=diff-quiet
+
+define signext i32 @main()  {
+entry:
+  ret i32 0
+}
+
+define internal void @f() {
+entry:
+  ret void
+}
+
+