Overload field_sensitivityt::apply for ssa_exprt

For two of the eight call sites of field_sensitivityt::apply we know at
compile time that an ssa_exprt is being passed in. We can thus avoid
redundant is-it-an-SSA-expression tests for those cases, and also know
that we do not need to look at any operands.

Author: tautschnig

src/goto-symex/field_sensitivity.cpp

@@ -18,6 +18,18 @@ Author: Michael Tautschnig
 
 #define ENABLE_ARRAY_FIELD_SENSITIVITY
 
+exprt field_sensitivityt::apply(
+  const namespacet &ns,
+  goto_symex_statet &state,
+  ssa_exprt ssa_expr,
+  bool write) const
+{
+  if(!run_apply || write)
+    return std::move(ssa_expr);
+  else
+    return get_fields(ns, state, ssa_expr);
+}
+
 exprt field_sensitivityt::apply(
   const namespacet &ns,
   goto_symex_statet &state,
@@ -33,9 +45,9 @@ exprt field_sensitivityt::apply(
       *it = apply(ns, state, std::move(*it), write);
   }
 
-  if(is_ssa_expr(expr) && !write)
+  if(!write && is_ssa_expr(expr))
   {
-    return get_fields(ns, state, to_ssa_expr(expr));
+    return apply(ns, state, to_ssa_expr(expr), write);
   }
   else if(
     !write && expr.id() == ID_member &&

src/goto-symex/field_sensitivity.h

@@ -119,6 +119,12 @@ class field_sensitivityt
   exprt
   apply(const namespacet &ns, goto_symex_statet &state, exprt expr, bool write)
     const;
+  /// \copydoc apply(const namespacet&,goto_symex_statet&,exprt,bool) const
+  exprt apply(
+    const namespacet &ns,
+    goto_symex_statet &state,
+    ssa_exprt expr,
+    bool write) const;
 
   /// Compute an expression representing the individual components of a
   /// field-sensitive SSA representation of \p ssa_expr.