MoveOnlyWrappedTypeEliminator: handle open_existential_box instructions

Fixes a compiler crash

rdar://136460032

Author: eeckstein

lib/SILOptimizer/Mandatory/MoveOnlyWrappedTypeEliminator.cpp

@@ -199,6 +199,7 @@ struct SILMoveOnlyWrappedTypeEliminatorVisitor
   NO_UPDATE_NEEDED(Object)
   NO_UPDATE_NEEDED(OpenExistentialRef)
   NO_UPDATE_NEEDED(OpenExistentialAddr)
+  NO_UPDATE_NEEDED(OpenExistentialBox)
   NO_UPDATE_NEEDED(ConvertFunction)
   NO_UPDATE_NEEDED(RefToBridgeObject)
   NO_UPDATE_NEEDED(BridgeObjectToRef)

test/SILOptimizer/moveonly_type_eliminator.sil

@@ -4,6 +4,7 @@
 sil_stage raw
 
 import Builtin
+import Swift
 
 //////////////////
 // Declarations //
@@ -38,8 +39,6 @@ struct KlassPair {
 
 sil @use_klass : $@convention(thin) (@guaranteed Klass) -> ()
 
-protocol Error {}
-
 ///////////
 // Tests //
 ///////////
@@ -616,6 +615,17 @@ bb0(%x : @guaranteed $any Error):
   return %em : $@thick any Error.Type
 }
 
+// CHECK-LABEL: sil [ossa] @existential_box :
+// CHECK:         %1 = open_existential_box %0 : $any Error
+// CHECK-LABEL: } // end sil function 'existential_box'
+sil [ossa] @existential_box : $@convention(thin) (@guaranteed any Error) -> () {
+bb0(%x : @guaranteed $any Error):
+  %y = copyable_to_moveonlywrapper [guaranteed] %x : $any Error
+  %o = open_existential_box %y : $@moveOnly (any Error) to $*@opened("01234567-89AB-CDEF-0123-000000000000", Error) Self
+  %r = tuple ()
+  return %r : $()
+}
+
 // CHECK-LABEL: sil [ossa] @builtin_tsanInoutAccess : {{.*}} {
 // CHECK:         builtin "tsanInoutAccess"
 // CHECK-LABEL: } // end sil function 'builtin_tsanInoutAccess'