Leave typecasts on variables on stack

Instead of removing all typecasts from variables on the stack, we extract the
necessary information of the bare expression from a temporary variable via a
`reference_wrapper`.

Author: Matthias Güdemann

jbmc/src/java_bytecode/java_bytecode_convert_method.cpp

@@ -25,6 +25,7 @@ Author: Daniel Kroening, kroening@kroening.com
 #include <util/arith_tools.h>
 #include <util/c_types.h>
 #include <util/expr_initializer.h>
+#include <util/expr_util.h>
 #include <util/ieee_float.h>
 #include <util/invariant.h>
 #include <util/namespace.h>
@@ -3184,28 +3185,34 @@ void java_bytecode_convert_methodt::save_stack_entries(
 {
   for(auto &stack_entry : stack)
   {
+    // remove typecasts if existing
+    const auto &entry = skip_typecast(stack_entry);
+
     // variables or static fields and symbol -> save symbols with same id
-    if((write_type==bytecode_write_typet::VARIABLE ||
-        write_type==bytecode_write_typet::STATIC_FIELD) &&
-       stack_entry.id()==ID_symbol)
+    if(
+      (write_type == bytecode_write_typet::VARIABLE ||
+       write_type == bytecode_write_typet::STATIC_FIELD) &&
+      entry.id() == ID_symbol)
     {
-      const symbol_exprt &var=to_symbol_expr(stack_entry);
-      if(var.get_identifier()==identifier)
+      if(to_symbol_expr(entry).get_identifier() == identifier)
         create_stack_tmp_var(tmp_var_prefix, tmp_var_type, block, stack_entry);
     }
 
     // array reference and dereference -> save all references on the stack
-    else if(write_type==bytecode_write_typet::ARRAY_REF &&
-            stack_entry.id()==ID_dereference)
+    else if(
+      write_type == bytecode_write_typet::ARRAY_REF &&
+      entry.id() == ID_dereference)
+    {
       create_stack_tmp_var(tmp_var_prefix, tmp_var_type, block, stack_entry);
+    }
 
     // field and member access -> compare component name
-    else if(write_type==bytecode_write_typet::FIELD &&
-            stack_entry.id()==ID_member)
+    else if(
+      write_type == bytecode_write_typet::FIELD &&
+      entry.id() == ID_member)
     {
-      const irep_idt &entry_id=
-        to_member_expr(stack_entry).get_component_name();
-      if(entry_id==identifier)
+      const irep_idt &entry_id = to_member_expr(entry).get_component_name();
+      if(entry_id == identifier)
         create_stack_tmp_var(tmp_var_prefix, tmp_var_type, block, stack_entry);
     }
   }