[ownership] When erroring since we visited an instruction that we should never visit, dump the instruction.

Author: gottesmm

lib/SIL/OperandOwnership.cpp

@@ -110,7 +110,9 @@ class OperandOwnershipKindClassifier
 #define SHOULD_NEVER_VISIT_INST(INST)                                          \
   OperandOwnershipKindMap OperandOwnershipKindClassifier::visit##INST##Inst(   \
       INST##Inst *i) {                                                         \
-    llvm_unreachable("Visited instruction that should never be visited?!");    \
+    llvm::errs() << "Unhandled inst: " << *i;                                  \
+    llvm::report_fatal_error(                                                  \
+        "Visited instruction that should never be visited?!");                 \
   }
 SHOULD_NEVER_VISIT_INST(AllocBox)
 SHOULD_NEVER_VISIT_INST(AllocExistentialBox)