added variants of goto_programt::insert_before/after that take instruction

This avoids duplicate initialization of the inserted instruction.

Author: Daniel Kroening

src/goto-programs/goto_program.h

@@ -573,6 +573,14 @@ class goto_programt
     return instructions.insert(target, instructiont());
   }
 
+  /// Insertion before the instruction pointed-to by the given instruction
+  /// iterator `target`.
+  /// \return newly inserted location
+  targett insert_before(const_targett target, const instructiont &i)
+  {
+    return instructions.insert(target, i);
+  }
+
   /// Insertion after the instruction pointed-to by the given instruction
   /// iterator `target`.
   /// \return newly inserted location
@@ -581,6 +589,14 @@ class goto_programt
     return instructions.insert(std::next(target), instructiont());
   }
 
+  /// Insertion after the instruction pointed-to by the given instruction
+  /// iterator `target`.
+  /// \return newly inserted location
+  targett insert_after(const_targett target, const instructiont &i)
+  {
+    return instructions.insert(std::next(target), i);
+  }
+
   /// Appends the given program `p` to `*this`. `p` is destroyed.
   void destructive_append(goto_programt &p)
   {