SMV: set type

This fixes typechecking for set literals, assignments from set literals to
variables of the element type, and typechecking for the "in" set membership
operator.

Author: kroening

regression/smv/expressions/smv_set2.smv

@@ -7,3 +7,6 @@ ASSIGN init(x) := {1, 2, 3};
        next(x) := x;
 
 SPEC x in my_set;
+
+-- the rhs set can be a singleton
+SPEC (x in 1) | (x in 2);

regression/smv/expressions/smv_set3.desc

@@ -0,0 +1,10 @@
+KNOWNBUG
+smv_set3.smv
+--bdd
+^\[spec1\] x in my_set: PROVED$
+^EXIT=0$
+^SIGNAL=0$
+--
+^warning: ignoring
+--
+The smv_setin operator is not implemented.

src/hw_cbmc_irep_ids.h

@@ -23,6 +23,7 @@ IREP_ID_ONE(smv_next)
 IREP_ID_ONE(smv_iff)
 IREP_ID_TWO(C_smv_iff, "#smv_iff")
 IREP_ID_ONE(smv_resize)
+IREP_ID_ONE(smv_set)
 IREP_ID_ONE(smv_setin)
 IREP_ID_ONE(smv_setnotin)
 IREP_ID_ONE(smv_signed_cast)

src/smvlang/expr2smv.cpp

@@ -902,6 +902,10 @@ std::string type2smv(const typet &type, const namespacet &ns)
   {
     return type.get_string(ID_from) + ".." + type.get_string(ID_to);
   }
+  else if(type.id() == ID_smv_set)
+  {
+    return "set";
+  }
   else if(type.id()=="submodule")
   {
     auto code = type.get_string(ID_identifier);

src/smvlang/parser.y

@@ -176,7 +176,6 @@ static void new_module(YYSTYPE &module)
 %token LTLWFF_Token	"LTLWFF"
 %token PSLWFF_Token	"PSLWFF"
 %token COMPWFF_Token	"COMPWFF"
-%token IN_Token		"IN"
 %token MIN_Token	"MIN"
 %token MAX_Token	"MAX"
 %token MIRROR_Token	"MIRROR"
@@ -289,7 +288,7 @@ static void new_module(YYSTYPE &module)
 %left  EX_Token AX_Token EF_Token AF_Token EG_Token AG_Token E_Token A_Token U_Token R_Token V_Token F_Token G_Token H_Token O_Token S_Token T_Token X_Token Y_Token Z_Token EBF_Token ABF_Token EBG_Token ABG_Token
 %left  EQUAL_Token NOTEQUAL_Token LT_Token GT_Token LE_Token GE_Token
 %left  union_Token
-%left  IN_Token NOTIN_Token
+%left  in_Token
 %left  mod_Token /* Precedence from CMU SMV, different from NuSMV */
 %left  LTLT_Token GTGT_Token
 %left  PLUS_Token MINUS_Token
@@ -673,7 +672,7 @@ formula    : term
 term       : variable_identifier
            | next_Token '(' term ')'  { init($$, ID_smv_next); mto($$, $3); }
            | '(' formula ')'          { $$=$2; }
-           | '{' formula_list '}'     { $$=$2; stack_expr($$).id("smv_nondet_choice"); }
+           | '{' formula_list '}'     { $$=$2; stack_expr($$).id(ID_smv_set); }
            | INC_Token '(' term ')'   { init($$, "inc"); mto($$, $3); }
            | DEC_Token '(' term ')'   { init($$, "dec"); mto($$, $3); }
            | ADD_Token '(' term ',' term ')' { j_binary($$, $3, ID_plus, $5); }
@@ -709,8 +708,7 @@ term       : variable_identifier
            | term GT_Token       term { binary($$, $1, ID_gt, $3); }
            | term GE_Token       term { binary($$, $1, ID_ge, $3); }
            | term union_Token    term { binary($$, $1, ID_smv_union, $3); }
-           | term IN_Token       term { binary($$, $1, ID_smv_setin, $3); }
-           | term NOTIN_Token    term { binary($$, $1, ID_smv_setnotin, $3); }
+           | term in_Token       term { binary($$, $1, ID_smv_setin, $3); }
            | extend_Token '(' term ',' term ')' { binary($$, $3, ID_smv_extend, $5); }
            | resize_Token '(' term ',' term ')' { binary($$, $3, ID_smv_resize, $5); }
            | signed_Token '(' term ')' { init($$, ID_smv_signed_cast); mto($$, $3); }

src/smvlang/scanner.l

@@ -101,7 +101,6 @@ void newlocation(YYSTYPE &x)
 "LTLWFF"	token(LTLWFF_Token);
 "PSLWFF"	token(PSLWFF_Token);
 "COMPWFF"	token(COMPWFF_Token);
-"IN"		token(IN_Token);
 "MIN"		token(MIN_Token);
 "MAX"		token(MAX_Token);
 "MIRROR"	token(MIRROR_Token);

src/smvlang/smv_typecheck.cpp

@@ -1001,7 +1001,26 @@ void smv_typecheckt::typecheck_expr_rec(exprt &expr, modet mode)
   }
   else if(expr.id() == ID_smv_setin)
   {
-    expr.type()=bool_typet();
+    auto &lhs = to_binary_expr(expr).lhs();
+    auto &rhs = to_binary_expr(expr).rhs();
+
+    typecheck_expr_rec(lhs, mode);
+    typecheck_expr_rec(rhs, mode);
+
+    // The RHS can be a set or a singleton
+    if(rhs.type().id() == ID_smv_set)
+    {
+    }
+    else
+    {
+      typet op_type =
+        type_union(lhs.type(), rhs.type(), expr.source_location());
+
+      convert_expr_to(lhs, op_type);
+      convert_expr_to(rhs, op_type);
+    }
+
+    expr.type() = bool_typet();
   }
   else if(expr.id() == ID_smv_setnotin)
   {
@@ -1232,6 +1251,11 @@ void smv_typecheckt::typecheck_expr_rec(exprt &expr, modet mode)
         << "signed operand must have unsigned word type";
     }
   }
+  else if(expr.id() == ID_smv_set)
+  {
+    // a set literal
+    expr.type() = typet{ID_smv_set};
+  }
   else
   {
     throw errort().with_location(expr.find_source_location())
@@ -1285,28 +1309,50 @@ Function: smv_typecheckt::convert_expr_to
 
 \*******************************************************************/
 
-void smv_typecheckt::convert_expr_to(exprt &expr, const typet &type)
+void smv_typecheckt::convert_expr_to(exprt &expr, const typet &dest_type)
 {
-  PRECONDITION(type.is_not_nil());
+  const auto &src_type = expr.type();
 
-  if(expr.type() != type)
+  PRECONDITION(dest_type.is_not_nil());
+
+  if(src_type != dest_type)
   {
-    if(type.id() == ID_signedbv || type.id() == ID_unsignedbv)
+    if(src_type.id() == ID_smv_set && expr.id() == ID_smv_set)
+    {
+      // sets can be assigned to scalars, which yields a nondeterministic
+      // choice
+      std::string identifier =
+        module + "::var::" + std::to_string(nondet_count++);
+
+      expr.set(ID_identifier, identifier);
+      expr.set("#smv_nondet_choice", true);
+
+      expr.id(ID_constraint_select_one);
+      expr.type() = dest_type;
+
+      // apply recursively
+      for(auto &op : expr.operands())
+        convert_expr_to(op, dest_type);
+
+      return;
+    }
+
+    if(dest_type.id() == ID_signedbv || dest_type.id() == ID_unsignedbv)
     {
       // no implicit conversion
     }
-    else if(type.id() == ID_range)
+    else if(dest_type.id() == ID_range)
     {
-      if(expr.type().id() == ID_range)
+      if(src_type.id() == ID_range)
       {
         // range to range
         if(expr.id() == ID_constant)
         {
           // re-type the constant
           auto value = numeric_cast_v<mp_integer>(to_constant_expr(expr));
-          if(to_range_type(type).includes(value))
+          if(to_range_type(dest_type).includes(value))
           {
-            expr = from_integer(value, type);
+            expr = from_integer(value, dest_type);
             return;
           }
         }
@@ -1318,26 +1364,40 @@ void smv_typecheckt::convert_expr_to(exprt &expr, const typet &type)
           for(auto &op : expr.operands())
           {
             if(!condition)
-              convert_expr_to(op, type);
+              convert_expr_to(op, dest_type);
 
             condition = !condition;
           }
-          expr.type() = type;
+          expr.type() = dest_type;
           return;
         }
         else
         {
-          expr = typecast_exprt{expr, type};
+          expr = typecast_exprt{expr, dest_type};
           return;
         }
       }
+      else if(src_type.id() == ID_integer)
+      {
+        // integer to range
+        if(expr.id() == ID_constant)
+        {
+          // re-type the constant
+          auto value = numeric_cast_v<mp_integer>(to_constant_expr(expr));
+          if(to_range_type(dest_type).includes(value))
+          {
+            expr = from_integer(value, dest_type);
+            return;
+          }
+        }
+      }
     }
-    else if(type.id() == ID_bool)
+    else if(dest_type.id() == ID_bool)
     {
       // legacy -- convert 0/1 to false/true
-      if(expr.type().id() == ID_range)
+      if(src_type.id() == ID_range)
       {
-        auto &range_type = to_range_type(expr.type());
+        auto &range_type = to_range_type(src_type);
         if(range_type.get_from() == 0 && range_type.get_to() == 0)
         {
           expr = false_exprt{};
@@ -1350,43 +1410,41 @@ void smv_typecheckt::convert_expr_to(exprt &expr, const typet &type)
         }
       }
     }
-    else if(type.id() == ID_enumeration)
+    else if(dest_type.id() == ID_enumeration)
     {
-      auto &e_type = to_enumeration_type(type);
+      auto &e_type = to_enumeration_type(dest_type);
 
-      if(expr.id() == ID_constant && expr.type().id() == ID_enumeration)
+      if(expr.id() == ID_constant && src_type.id() == ID_enumeration)
       {
-        if(is_contained_in(to_enumeration_type(expr.type()), e_type))
+        if(is_contained_in(to_enumeration_type(src_type), e_type))
         {
           // re-type the constant
-          expr.type() = type;
+          expr.type() = dest_type;
           return;
         }
         else
         {
           throw errort().with_location(expr.find_source_location())
             << "enum " << to_string(expr) << " not a member of "
-            << to_string(type);
+            << to_string(dest_type);
         }
       }
       else if(expr.id() == ID_typecast)
       {
         // created by type unions
         auto &op = to_typecast_expr(expr).op();
-        if(
-          expr.type().id() == ID_enumeration &&
-          op.type().id() == ID_enumeration)
+        if(src_type.id() == ID_enumeration && op.type().id() == ID_enumeration)
         {
-          convert_expr_to(op, type);
+          convert_expr_to(op, dest_type);
           expr = std::move(op);
         }
       }
     }
 
     throw errort().with_location(expr.find_source_location())
-      << "Expected expression of type `" << to_string(type)
+      << "Expected expression of type `" << to_string(dest_type)
       << "', but got expression `" << to_string(expr) << "', which is of type `"
-      << to_string(expr.type()) << "'";
+      << to_string(src_type) << "'";
   }
 }