Define a find_symbol_identifiers function

This compute a similar set to the find_symbols(const exprt &,
find_symbols_sett &, bool, bool) function but returns the computed set.

Author: romainbrenguier

src/goto-instrument/concurrency.cpp

@@ -131,10 +131,8 @@ void concurrency_instrumentationt::instrument(
 
 void concurrency_instrumentationt::collect(const exprt &expr)
 {
-  for(const auto &symbol_expr : find_symbols(expr))
+  for(const auto &identifier : find_symbol_identifiers(expr))
   {
-    const irep_idt &identifier = symbol_expr.get_identifier();
-
     namespacet ns(symbol_table);
     const symbolt &symbol = ns.lookup(identifier);
 

src/util/find_symbols.cpp

@@ -88,6 +88,16 @@ std::set<symbol_exprt> find_symbols(const exprt &src)
     .map([](const exprt &e) { return to_symbol_expr(e); });
 }
 
+std::unordered_set<irep_idt> find_symbol_identifiers(const exprt &src)
+{
+  std::unordered_set<irep_idt> result;
+  src.visit_pre([&](const exprt &e) {
+    if(e.id() == ID_symbol)
+      result.insert(to_symbol_expr(e).get_identifier());
+  });
+  return result;
+}
+
 void find_symbols(kindt kind, const typet &src, find_symbols_sett &dest);
 
 void find_symbols(kindt kind, const exprt &src, find_symbols_sett &dest)

src/util/find_symbols.h

@@ -63,6 +63,9 @@ void find_symbols(
 /// Find sub expressions with id ID_symbol
 std::set<symbol_exprt> find_symbols(const exprt &src);
 
+/// Find identifiers of the sub expressions with id ID_symbol
+std::unordered_set<irep_idt> find_symbol_identifiers(const exprt &src);
+
 /// \return true if one of the symbols in \p src is present in \p symbols
 bool has_symbol(
   const exprt &src,