Infer cond_expr in SSA_assignment_step

This can be deduced fro lhs and rhs without having to give it to the
constructor.

Author: romainbrenguier

src/goto-symex/ssa_step.cpp

@@ -221,7 +221,6 @@ SSA_assignment_stept::SSA_assignment_stept(
   exprt _ssa_full_lhs,
   exprt _original_full_lhs,
   exprt _ssa_rhs,
-  exprt _cond_expr,
   symex_targett::assignment_typet _assignment_type)
   : SSA_stept(source, goto_trace_stept::typet::ASSIGNMENT)
 {
@@ -231,7 +230,7 @@ SSA_assignment_stept::SSA_assignment_stept(
   original_full_lhs = std::move(_original_full_lhs);
   ssa_rhs = std::move(_ssa_rhs);
   assignment_type = _assignment_type;
-  cond_expr = std::move(_cond_expr);
+  cond_expr = equal_exprt(ssa_lhs, ssa_rhs);
   hidden =
     assignment_type != symex_targett::assignment_typet::STATE &&
     assignment_type !=

src/goto-symex/ssa_step.h

@@ -205,7 +205,6 @@ class SSA_assignment_stept : public SSA_stept
     exprt ssa_full_lhs,
     exprt original_full_lhs,
     exprt ssa_rhs,
-    exprt cond_expr,
     symex_targett::assignment_typet assignment_type);
 };
 

src/goto-symex/symex_target_equation.cpp

@@ -121,7 +121,6 @@ void symex_target_equationt::assignment(
     ssa_full_lhs,
     original_full_lhs,
     ssa_rhs,
-    equal_exprt(ssa_lhs, ssa_rhs),
     assignment_type});
 
   merge_ireps(SSA_steps.back());