Add support for STL NOT instruction

Extends the language subset of Statement List by the NOT instruction,
used for simply negating the current state of the rlo.

Author: MatWise

src/statement-list/scanner.l

@@ -116,6 +116,7 @@ void statement_list_scanner_init()
   CLR                 { loc(); return TOK_CLR_RLO; }
   S                   { loc(); return TOK_SET; }
   R                   { loc(); return TOK_RESET; }
+  NOT                 { loc(); return TOK_NOT; }
   A                   { loc(); return TOK_AND; }
   AN                  { loc(); return TOK_AND_NOT; }
   O                   { loc(); return TOK_OR; }

src/statement-list/statement_list_typecheck.cpp

@@ -387,6 +387,8 @@ void statement_list_typecheckt::typecheck_statement_list_instruction(
     typecheck_statement_list_accu_real_lte(op_code);
   else if(ID_statement_list_accu_real_gte == statement)
     typecheck_statement_list_accu_real_gte(op_code);
+  else if(ID_statement_list_not == statement)
+    typecheck_statement_list_not(op_code);
   else if(ID_statement_list_and == statement)
     typecheck_statement_list_and(op_code, tia_element);
   else if(ID_statement_list_and_not == statement)
@@ -753,6 +755,20 @@ void statement_list_typecheckt::typecheck_statement_list_accu_real_gte(
   typecheck_accumulator_compare_instruction(ID_ge);
 }
 
+void statement_list_typecheckt::typecheck_statement_list_not(
+  const codet &op_code)
+{
+  typecheck_instruction_without_operand(op_code);
+  if(fc_bit)
+  {
+    const not_exprt unsimplified{rlo_bit};
+    rlo_bit = simplify_expr(unsimplified, namespacet(symbol_table));
+    or_bit = false;
+  }
+  else
+    initialize_bit_expression(false_exprt{});
+}
+
 void statement_list_typecheckt::typecheck_statement_list_and(
   const codet &op_code,
   const symbolt &tia_element)

src/statement-list/statement_list_typecheck.h

@@ -364,6 +364,11 @@ class statement_list_typecheckt : public typecheckt
 
   // Bit Logic instructions
 
+  /// Performs a typecheck on a STL boolean NOT instruction. Reads and modifies
+  /// the RLO, OR and FC bit.
+  /// \param op_code: OP code of the instruction.
+  void typecheck_statement_list_not(const codet &op_code);
+
   /// Performs a typecheck on a STL boolean And instruction. Reads and modifies
   /// the RLO, OR and FC bit.
   /// \param op_code: OP code of the instruction.