Clean-up irep-id emptyness checks in util

Author: peterschrammel

src/util/find_symbols.cpp

@@ -153,7 +153,7 @@ void find_symbols(kindt kind, const typet &src, find_symbols_sett &dest)
       find_symbols(kind, *it, dest);
 
       // irep_idt identifier=it->get_identifier();
-      // if(identifier!=irep_idt() && (kind==F_TYPE || kind==F_BOTH))
+      // if(!identifier.empty() && (kind==F_TYPE || kind==F_BOTH))
       //  dest.insert(identifier);
     }
   }

src/util/simplify_expr.cpp

@@ -2322,7 +2322,7 @@ bool simplify_exprt::simplify_rec(exprt &expr)
   {
     const exprt &new_expr=cache_result.first->second;
 
-    if(new_expr.id()==irep_idt())
+    if(new_expr.id().empty())
       return true; // no change
 
     expr=new_expr;

src/util/simplify_utils.cpp

@@ -99,7 +99,7 @@ static bool sort_and_join(
   const struct saj_tablet &saj_entry,
   const irep_idt &type_id)
 {
-  for(unsigned i=0; saj_entry.type_ids[i]!=irep_idt(); i++)
+  for(unsigned i=0; !saj_entry.type_ids[i].empty(); i++)
     if(type_id==saj_entry.type_ids[i])
       return true;
 
@@ -112,7 +112,7 @@ static const struct saj_tablet &sort_and_join(
 {
   unsigned i=0;
 
-  for( ; saj_table[i].id!=irep_idt(); i++)
+  for( ; !saj_table[i].id.empty(); i++)
     if(id==saj_table[i].id &&
        sort_and_join(saj_table[i], type_id))
       return saj_table[i];
@@ -129,7 +129,7 @@ bool sort_and_join(exprt &expr)
 
   const struct saj_tablet &saj_entry=
     sort_and_join(expr.id(), expr.type().id());
-  if(saj_entry.id==irep_idt())
+  if(saj_entry.id.empty())
     return true;
 
   // check operand types

src/util/std_types.cpp

@@ -15,14 +15,14 @@ Author: Daniel Kroening, kroening@kroening.com
 std::size_t fixedbv_typet::get_integer_bits() const
 {
   const irep_idt integer_bits=get(ID_integer_bits);
-  assert(integer_bits!=irep_idt());
+  assert(!integer_bits.empty());
   return unsafe_string2unsigned(id2string(integer_bits));
 }
 
 std::size_t floatbv_typet::get_f() const
 {
   const irep_idt &f=get(ID_f);
-  assert(f!=irep_idt());
+  assert(!f.empty());
   return unsafe_string2unsigned(id2string(f));
 }