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smt2_conv.cpp
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/*******************************************************************\
Module: SMT Backend
Author: Daniel Kroening, [email protected]
\*******************************************************************/
/// \file
/// SMT Backend
#include "smt2_conv.h"
#include <util/arith_tools.h>
#include <util/bitvector_expr.h>
#include <util/byte_operators.h>
#include <util/c_types.h>
#include <util/config.h>
#include <util/expr_iterator.h>
#include <util/expr_util.h>
#include <util/fixedbv.h>
#include <util/floatbv_expr.h>
#include <util/format_expr.h>
#include <util/ieee_float.h>
#include <util/invariant.h>
#include <util/mathematical_expr.h>
#include <util/namespace.h>
#include <util/pointer_offset_size.h>
#include <util/pointer_predicates.h>
#include <util/prefix.h>
#include <util/range.h>
#include <util/simplify_expr.h>
#include <util/std_expr.h>
#include <util/string2int.h>
#include <util/string_constant.h>
#include <util/threeval.h>
#include <solvers/flattening/boolbv_width.h>
#include <solvers/flattening/c_bit_field_replacement_type.h>
#include <solvers/floatbv/float_bv.h>
#include <solvers/prop/literal_expr.h>
#include "smt2_tokenizer.h"
#include <cstdint>
// Mark different kinds of error conditions
// Unexpected types and other combinations not implemented and not
// expected to be needed
#define UNEXPECTEDCASE(S) PRECONDITION_WITH_DIAGNOSTICS(false, S);
// General todos
#define SMT2_TODO(S) PRECONDITION_WITH_DIAGNOSTICS(false, "TODO: " S)
smt2_convt::smt2_convt(
const namespacet &_ns,
const std::string &_benchmark,
const std::string &_notes,
const std::string &_logic,
solvert _solver,
std::ostream &_out)
: use_FPA_theory(false),
use_array_of_bool(false),
use_as_const(false),
use_check_sat_assuming(false),
use_datatypes(false),
use_lambda_for_array(false),
emit_set_logic(true),
ns(_ns),
out(_out),
benchmark(_benchmark),
notes(_notes),
logic(_logic),
solver(_solver),
boolbv_width(_ns),
pointer_logic(_ns),
no_boolean_variables(0)
{
// We set some defaults differently
// for some solvers.
switch(solver)
{
case solvert::GENERIC:
break;
case solvert::BITWUZLA:
use_FPA_theory = true;
use_array_of_bool = true;
use_as_const = true;
use_check_sat_assuming = true;
use_lambda_for_array = true;
emit_set_logic = false;
break;
case solvert::BOOLECTOR:
break;
case solvert::CPROVER_SMT2:
use_FPA_theory = true;
use_array_of_bool = true;
use_as_const = true;
use_check_sat_assuming = true;
emit_set_logic = false;
break;
case solvert::CVC3:
break;
case solvert::CVC4:
logic = "ALL";
use_array_of_bool = true;
use_as_const = true;
break;
case solvert::CVC5:
logic = "ALL";
use_FPA_theory = true;
use_array_of_bool = true;
use_as_const = true;
use_check_sat_assuming = true;
use_datatypes = true;
break;
case solvert::MATHSAT:
break;
case solvert::YICES:
break;
case solvert::Z3:
use_array_of_bool = true;
use_as_const = true;
use_check_sat_assuming = true;
use_lambda_for_array = true;
emit_set_logic = false;
use_datatypes = true;
break;
}
write_header();
}
std::string smt2_convt::decision_procedure_text() const
{
return "SMT2";
}
void smt2_convt::print_assignment(std::ostream &os) const
{
// Boolean stuff
for(std::size_t v=0; v<boolean_assignment.size(); v++)
os << "b" << v << "=" << boolean_assignment[v] << "\n";
// others
}
tvt smt2_convt::l_get(literalt l) const
{
if(l.is_true())
return tvt(true);
if(l.is_false())
return tvt(false);
INVARIANT(
l.var_no() < boolean_assignment.size(),
"variable number shall be within bounds");
return tvt(boolean_assignment[l.var_no()]^l.sign());
}
void smt2_convt::write_header()
{
out << "; SMT 2" << "\n";
switch(solver)
{
// clang-format off
case solvert::GENERIC: break;
case solvert::BITWUZLA: out << "; Generated for Bitwuzla\n"; break;
case solvert::BOOLECTOR: out << "; Generated for Boolector\n"; break;
case solvert::CPROVER_SMT2:
out << "; Generated for the CPROVER SMT2 solver\n"; break;
case solvert::CVC3: out << "; Generated for CVC 3\n"; break;
case solvert::CVC4: out << "; Generated for CVC 4\n"; break;
case solvert::CVC5: out << "; Generated for CVC 5\n"; break;
case solvert::MATHSAT: out << "; Generated for MathSAT\n"; break;
case solvert::YICES: out << "; Generated for Yices\n"; break;
case solvert::Z3: out << "; Generated for Z3\n"; break;
// clang-format on
}
out << "(set-info :source \"" << notes << "\")" << "\n";
out << "(set-option :produce-models true)" << "\n";
// We use a broad mixture of logics, so on some solvers
// its better not to declare here.
// set-logic should come after setting options
if(emit_set_logic && !logic.empty())
out << "(set-logic " << logic << ")" << "\n";
}
void smt2_convt::write_footer()
{
out << "\n";
// fix up the object sizes
for(const auto &object : object_sizes)
define_object_size(object.second, object.first);
if(use_check_sat_assuming && !assumptions.empty())
{
out << "(check-sat-assuming (";
for(const auto &assumption : assumptions)
convert_literal(to_literal_expr(assumption).get_literal());
out << "))\n";
}
else
{
// add the assumptions, if any
if(!assumptions.empty())
{
out << "; assumptions\n";
for(const auto &assumption : assumptions)
{
out << "(assert ";
convert_literal(to_literal_expr(assumption).get_literal());
out << ")"
<< "\n";
}
}
out << "(check-sat)\n";
}
out << "\n";
if(solver!=solvert::BOOLECTOR)
{
for(const auto &id : smt2_identifiers)
out << "(get-value (" << id << "))"
<< "\n";
}
out << "\n";
out << "(exit)\n";
out << "; end of SMT2 file"
<< "\n";
}
/// Returns true iff \p type has effective width of zero bits.
static bool is_zero_width(const typet &type, const namespacet &ns)
{
if(type.id() == ID_empty)
return true;
else if(type.id() == ID_struct_tag)
return is_zero_width(ns.follow_tag(to_struct_tag_type(type)), ns);
else if(type.id() == ID_union_tag)
return is_zero_width(ns.follow_tag(to_union_tag_type(type)), ns);
else if(type.id() == ID_struct || type.id() == ID_union)
{
for(const auto &comp : to_struct_union_type(type).components())
{
if(!is_zero_width(comp.type(), ns))
return false;
}
return true;
}
else if(auto array_type = type_try_dynamic_cast<array_typet>(type))
{
// we ignore array_type->size().is_zero() for now as there may be
// out-of-bounds accesses that we need to model
return is_zero_width(array_type->element_type(), ns);
}
else
return false;
}
void smt2_convt::define_object_size(
const irep_idt &id,
const object_size_exprt &expr)
{
const exprt &ptr = expr.pointer();
std::size_t pointer_width = boolbv_width(ptr.type());
std::size_t number = 0;
std::size_t h=pointer_width-1;
std::size_t l=pointer_width-config.bv_encoding.object_bits;
for(const auto &o : pointer_logic.objects)
{
const typet &type = o.type();
auto size_expr = size_of_expr(type, ns);
if(
(o.id() != ID_symbol && o.id() != ID_string_constant) ||
!size_expr.has_value())
{
++number;
continue;
}
find_symbols(*size_expr);
out << "(assert (=> (= "
<< "((_ extract " << h << " " << l << ") ";
convert_expr(ptr);
out << ") (_ bv" << number << " " << config.bv_encoding.object_bits << "))"
<< "(= " << id << " ";
convert_expr(*size_expr);
out << ")))\n";
++number;
}
}
decision_proceduret::resultt smt2_convt::dec_solve(const exprt &assumption)
{
if(assumption.is_nil())
write_footer();
else
{
assumptions.push_back(literal_exprt(convert(assumption)));
write_footer();
assumptions.pop_back();
}
out.flush();
return decision_proceduret::resultt::D_ERROR;
}
exprt smt2_convt::get(const exprt &expr) const
{
if(expr.id()==ID_symbol)
{
const irep_idt &id=to_symbol_expr(expr).get_identifier();
identifier_mapt::const_iterator it=identifier_map.find(id);
if(it!=identifier_map.end())
return it->second.value;
return expr;
}
else if(expr.id()==ID_nondet_symbol)
{
const irep_idt &id=to_nondet_symbol_expr(expr).get_identifier();
identifier_mapt::const_iterator it=identifier_map.find(id);
if(it!=identifier_map.end())
return it->second.value;
}
else if(expr.id() == ID_literal)
{
auto l = to_literal_expr(expr).get_literal();
if(l_get(l).is_true())
return true_exprt();
else
return false_exprt();
}
else if(expr.id() == ID_not)
{
auto op = get(to_not_expr(expr).op());
if(op.is_true())
return false_exprt();
else if(op.is_false())
return true_exprt();
}
else if(
expr.is_constant() || expr.id() == ID_empty_union ||
(!expr.has_operands() && (expr.id() == ID_struct || expr.id() == ID_array)))
{
return expr;
}
else if(expr.has_operands())
{
exprt copy = expr;
for(auto &op : copy.operands())
{
exprt eval_op = get(op);
if(eval_op.is_nil())
return nil_exprt{};
op = std::move(eval_op);
}
return copy;
}
return nil_exprt();
}
constant_exprt smt2_convt::parse_literal(
const irept &src,
const typet &type)
{
// See http://www.grammatech.com/resources/smt/SMTLIBTutorial.pdf for the
// syntax of SMTlib2 literals.
//
// A literal expression is one of the following forms:
//
// * Numeral -- this is a natural number in decimal and is of the form:
// 0|([1-9][0-9]*)
// * Decimal -- this is a decimal expansion of a real number of the form:
// (0|[1-9][0-9]*)[.]([0-9]+)
// * Binary -- this is a natural number in binary and is of the form:
// #b[01]+
// * Hex -- this is a natural number in hexadecimal and is of the form:
// #x[0-9a-fA-F]+
//
// Right now I'm not parsing decimals. It'd be nice if we had a real YACC
// parser here, but whatever.
mp_integer value;
if(!src.id().empty())
{
const std::string &s=src.id_string();
if(s.size()>=2 && s[0]=='#' && s[1]=='b')
{
// Binary #b010101
value=string2integer(s.substr(2), 2);
}
else if(s.size()>=2 && s[0]=='#' && s[1]=='x')
{
// Hex #x012345
value=string2integer(s.substr(2), 16);
}
else
{
// Numeral
value=string2integer(s);
}
}
else if(src.get_sub().size()==2 &&
src.get_sub()[0].id()=="-") // (- 100)
{
value=-string2integer(src.get_sub()[1].id_string());
}
else if(src.get_sub().size()==3 &&
src.get_sub()[0].id()=="_" &&
// (_ bvDECIMAL_VALUE SIZE)
src.get_sub()[1].id_string().substr(0, 2)=="bv")
{
value=string2integer(src.get_sub()[1].id_string().substr(2));
}
else if(src.get_sub().size()==4 &&
src.get_sub()[0].id()=="fp") // (fp signbv exponentbv significandbv)
{
if(type.id()==ID_floatbv)
{
const floatbv_typet &floatbv_type=to_floatbv_type(type);
constant_exprt s1 = parse_literal(src.get_sub()[1], unsignedbv_typet(1));
constant_exprt s2 =
parse_literal(src.get_sub()[2], unsignedbv_typet(floatbv_type.get_e()));
constant_exprt s3 =
parse_literal(src.get_sub()[3], unsignedbv_typet(floatbv_type.get_f()));
const auto s1_int = numeric_cast_v<mp_integer>(s1);
const auto s2_int = numeric_cast_v<mp_integer>(s2);
const auto s3_int = numeric_cast_v<mp_integer>(s3);
// stitch the bits together
value = bitwise_or(
s1_int << (floatbv_type.get_e() + floatbv_type.get_f()),
bitwise_or((s2_int << floatbv_type.get_f()), s3_int));
}
else
value=0;
}
else if(src.get_sub().size()==4 &&
src.get_sub()[0].id()=="_" &&
src.get_sub()[1].id()=="+oo") // (_ +oo e s)
{
std::size_t e = unsafe_string2size_t(src.get_sub()[2].id_string());
std::size_t s = unsafe_string2size_t(src.get_sub()[3].id_string());
return ieee_floatt::plus_infinity(ieee_float_spect(s - 1, e)).to_expr();
}
else if(src.get_sub().size()==4 &&
src.get_sub()[0].id()=="_" &&
src.get_sub()[1].id()=="-oo") // (_ -oo e s)
{
std::size_t e = unsafe_string2size_t(src.get_sub()[2].id_string());
std::size_t s = unsafe_string2size_t(src.get_sub()[3].id_string());
return ieee_floatt::minus_infinity(ieee_float_spect(s - 1, e)).to_expr();
}
else if(src.get_sub().size()==4 &&
src.get_sub()[0].id()=="_" &&
src.get_sub()[1].id()=="NaN") // (_ NaN e s)
{
std::size_t e = unsafe_string2size_t(src.get_sub()[2].id_string());
std::size_t s = unsafe_string2size_t(src.get_sub()[3].id_string());
return ieee_floatt::NaN(ieee_float_spect(s - 1, e)).to_expr();
}
if(type.id()==ID_signedbv ||
type.id()==ID_unsignedbv ||
type.id()==ID_c_enum ||
type.id()==ID_c_bool)
{
return from_integer(value, type);
}
else if(type.id()==ID_c_enum_tag)
{
constant_exprt result =
from_integer(value, ns.follow_tag(to_c_enum_tag_type(type)));
// restore the c_enum_tag type
result.type() = type;
return result;
}
else if(type.id()==ID_fixedbv ||
type.id()==ID_floatbv)
{
std::size_t width=boolbv_width(type);
return constant_exprt(integer2bvrep(value, width), type);
}
else if(type.id()==ID_integer ||
type.id()==ID_range)
{
return from_integer(value, type);
}
else
UNREACHABLE_BECAUSE(
"smt2_convt::parse_literal should not be of unsupported type " +
type.id_string());
}
exprt smt2_convt::parse_array(
const irept &src,
const array_typet &type)
{
std::unordered_map<int64_t, exprt> operands_map;
walk_array_tree(&operands_map, src, type);
exprt::operandst operands;
// Try to find the default value, if there is none then set it
auto maybe_default_op = operands_map.find(-1);
exprt default_op;
if(maybe_default_op == operands_map.end())
default_op = nil_exprt();
else
default_op = maybe_default_op->second;
int64_t i = 0;
auto maybe_size = numeric_cast<std::int64_t>(type.size());
if(maybe_size.has_value())
{
while(i < maybe_size.value())
{
auto found_op = operands_map.find(i);
if(found_op != operands_map.end())
operands.emplace_back(found_op->second);
else
operands.emplace_back(default_op);
i++;
}
}
else
{
// Array size is unknown, keep adding with known indexes in order
// until we fail to find one.
auto found_op = operands_map.find(i);
while(found_op != operands_map.end())
{
operands.emplace_back(found_op->second);
i++;
found_op = operands_map.find(i);
}
operands.emplace_back(default_op);
}
return array_exprt(operands, type);
}
void smt2_convt::walk_array_tree(
std::unordered_map<int64_t, exprt> *operands_map,
const irept &src,
const array_typet &type)
{
if(src.get_sub().size()==4 && src.get_sub()[0].id()=="store")
{
// This is the SMT syntax being parsed here
// (store array index value)
// Recurse
walk_array_tree(operands_map, src.get_sub()[1], type);
const auto index_expr = parse_rec(src.get_sub()[2], type.size().type());
const constant_exprt index_constant = to_constant_expr(index_expr);
mp_integer tempint;
bool failure = to_integer(index_constant, tempint);
if(failure)
return;
long index = tempint.to_long();
exprt value = parse_rec(src.get_sub()[3], type.element_type());
operands_map->emplace(index, value);
}
else if(src.get_sub().size()==2 &&
src.get_sub()[0].get_sub().size()==3 &&
src.get_sub()[0].get_sub()[0].id()=="as" &&
src.get_sub()[0].get_sub()[1].id()=="const")
{
// (as const type_info default_value)
exprt default_value = parse_rec(src.get_sub()[1], type.element_type());
operands_map->emplace(-1, default_value);
}
else
{
auto bindings_it = current_bindings.find(src.id());
if(bindings_it != current_bindings.end())
walk_array_tree(operands_map, bindings_it->second, type);
}
}
exprt smt2_convt::parse_union(
const irept &src,
const union_typet &type)
{
// these are always flat
PRECONDITION(!type.components().empty());
const union_typet::componentt &first=type.components().front();
std::size_t width=boolbv_width(type);
exprt value = parse_rec(src, unsignedbv_typet(width));
if(value.is_nil())
return nil_exprt();
const typecast_exprt converted(value, first.type());
return union_exprt(first.get_name(), converted, type);
}
struct_exprt
smt2_convt::parse_struct(const irept &src, const struct_typet &type)
{
const struct_typet::componentst &components =
type.components();
struct_exprt result(exprt::operandst(components.size(), nil_exprt()), type);
if(components.empty())
return result;
if(use_datatypes)
{
// Structs look like:
// (mk-struct.1 <component0> <component1> ... <componentN>)
std::size_t j = 1;
for(std::size_t i=0; i<components.size(); i++)
{
const struct_typet::componentt &c=components[i];
if(is_zero_width(components[i].type(), ns))
{
result.operands()[i] = nil_exprt{};
}
else
{
DATA_INVARIANT(
src.get_sub().size() > j, "insufficient number of component values");
result.operands()[i] = parse_rec(src.get_sub()[j], c.type());
++j;
}
}
}
else
{
// These are just flattened, i.e., we expect to see a monster bit vector.
std::size_t total_width=boolbv_width(type);
const auto l = parse_literal(src, unsignedbv_typet(total_width));
const irep_idt binary =
integer2binary(numeric_cast_v<mp_integer>(l), total_width);
CHECK_RETURN(binary.size() == total_width);
std::size_t offset=0;
for(std::size_t i=0; i<components.size(); i++)
{
if(is_zero_width(components[i].type(), ns))
continue;
std::size_t component_width=boolbv_width(components[i].type());
INVARIANT(
offset + component_width <= total_width,
"struct component bits shall be within struct bit vector");
std::string component_binary=
"#b"+id2string(binary).substr(
total_width-offset-component_width, component_width);
result.operands()[i]=
parse_rec(irept(component_binary), components[i].type());
offset+=component_width;
}
}
return result;
}
exprt smt2_convt::parse_rec(const irept &src, const typet &type)
{
if(src.get_sub().size() == 3 && src.get_sub()[0].id() == ID_let)
{
// This is produced by Z3
// (let (....) (....))
auto previous_bindings = current_bindings;
for(const auto &binding : src.get_sub()[1].get_sub())
{
const irep_idt &name = binding.get_sub()[0].id();
current_bindings.emplace(name, binding.get_sub()[1]);
}
exprt result = parse_rec(src.get_sub()[2], type);
current_bindings = std::move(previous_bindings);
return result;
}
auto bindings_it = current_bindings.find(src.id());
if(bindings_it != current_bindings.end())
{
return parse_rec(bindings_it->second, type);
}
if(
type.id() == ID_signedbv || type.id() == ID_unsignedbv ||
type.id() == ID_integer || type.id() == ID_rational ||
type.id() == ID_real || type.id() == ID_c_enum ||
type.id() == ID_c_enum_tag || type.id() == ID_fixedbv ||
type.id() == ID_floatbv || type.id() == ID_c_bool)
{
return parse_literal(src, type);
}
else if(type.id()==ID_bool)
{
if(src.id()==ID_1 || src.id()==ID_true)
return true_exprt();
else if(src.id()==ID_0 || src.id()==ID_false)
return false_exprt();
}
else if(type.id()==ID_pointer)
{
// these come in as bit-vector literals
std::size_t width=boolbv_width(type);
constant_exprt bv_expr = parse_literal(src, unsignedbv_typet(width));
mp_integer v = numeric_cast_v<mp_integer>(bv_expr);
// split into object and offset
mp_integer pow=power(2, width-config.bv_encoding.object_bits);
pointer_logict::pointert ptr{numeric_cast_v<std::size_t>(v / pow), v % pow};
return annotated_pointer_constant_exprt(
bv_expr.get_value(),
pointer_logic.pointer_expr(ptr, to_pointer_type(type)));
}
else if(type.id()==ID_struct)
{
return parse_struct(src, to_struct_type(type));
}
else if(type.id() == ID_struct_tag)
{
auto struct_expr =
parse_struct(src, ns.follow_tag(to_struct_tag_type(type)));
// restore the tag type
struct_expr.type() = type;
return std::move(struct_expr);
}
else if(type.id()==ID_union)
{
return parse_union(src, to_union_type(type));
}
else if(type.id() == ID_union_tag)
{
auto union_expr = parse_union(src, ns.follow_tag(to_union_tag_type(type)));
// restore the tag type
union_expr.type() = type;
return union_expr;
}
else if(type.id()==ID_array)
{
return parse_array(src, to_array_type(type));
}
return nil_exprt();
}
void smt2_convt::convert_address_of_rec(
const exprt &expr,
const pointer_typet &result_type)
{
if(
expr.id() == ID_symbol || expr.is_constant() ||
expr.id() == ID_string_constant || expr.id() == ID_label)
{
const std::size_t object_bits = config.bv_encoding.object_bits;
const std::size_t max_objects = std::size_t(1) << object_bits;
const mp_integer object_id = pointer_logic.add_object(expr);
if(object_id >= max_objects)
{
throw analysis_exceptiont{
"too many addressed objects: maximum number of objects is set to 2^n=" +
std::to_string(max_objects) +
" (with n=" + std::to_string(object_bits) + "); " +
"use the `--object-bits n` option to increase the maximum number"};
}
out << "(concat (_ bv" << object_id << " " << object_bits << ")"
<< " (_ bv0 " << boolbv_width(result_type) - object_bits << "))";
}
else if(expr.id()==ID_index)
{
const index_exprt &index_expr = to_index_expr(expr);
const exprt &array = index_expr.array();
const exprt &index = index_expr.index();
if(index.is_zero())
{
if(array.type().id()==ID_pointer)
convert_expr(array);
else if(array.type().id()==ID_array)
convert_address_of_rec(array, result_type);
else
UNREACHABLE;
}
else
{
// this is really pointer arithmetic
index_exprt new_index_expr = index_expr;
new_index_expr.index() = from_integer(0, index.type());
address_of_exprt address_of_expr(
new_index_expr,
pointer_type(to_array_type(array.type()).element_type()));
plus_exprt plus_expr{address_of_expr, index};
convert_expr(plus_expr);
}
}
else if(expr.id()==ID_member)
{
const member_exprt &member_expr=to_member_expr(expr);
const exprt &struct_op=member_expr.struct_op();
const typet &struct_op_type = struct_op.type();
DATA_INVARIANT(
struct_op_type.id() == ID_struct || struct_op_type.id() == ID_struct_tag,
"member expression operand shall have struct type");
const struct_typet &struct_type = to_struct_type(ns.follow(struct_op_type));
const irep_idt &component_name = member_expr.get_component_name();
const auto offset = member_offset(struct_type, component_name, ns);
CHECK_RETURN(offset.has_value() && *offset >= 0);
unsignedbv_typet index_type(boolbv_width(result_type));
// pointer arithmetic
out << "(bvadd ";
convert_address_of_rec(struct_op, result_type);
convert_expr(from_integer(*offset, index_type));
out << ")"; // bvadd
}
else if(expr.id()==ID_if)
{
const if_exprt &if_expr = to_if_expr(expr);
out << "(ite ";
convert_expr(if_expr.cond());
out << " ";
convert_address_of_rec(if_expr.true_case(), result_type);
out << " ";
convert_address_of_rec(if_expr.false_case(), result_type);
out << ")";
}
else
INVARIANT(
false,
"operand of address of expression should not be of kind " +
expr.id_string());
}
static bool has_quantifier(const exprt &expr)
{
bool result = false;
expr.visit_post([&result](const exprt &node) {
if(node.id() == ID_exists || node.id() == ID_forall)
result = true;
});
return result;
}
literalt smt2_convt::convert(const exprt &expr)
{
PRECONDITION(expr.is_boolean());
// Three cases where no new handle is needed.
if(expr.is_true())
return const_literal(true);
else if(expr.is_false())
return const_literal(false);
else if(expr.id()==ID_literal)
return to_literal_expr(expr).get_literal();
// Need a new handle
out << "\n";
exprt prepared_expr = prepare_for_convert_expr(expr);
literalt l(no_boolean_variables, false);
no_boolean_variables++;
out << "; convert\n";
out << "; Converting var_no " << l.var_no() << " with expr ID of "
<< expr.id_string() << "\n";
// We're converting the expression, so store it in the defined_expressions
// store and in future we use the literal instead of the whole expression
// Note that here we are always converting, so we do not need to consider
// other literal kinds, only "|B###|"
// Z3 refuses get-value when a defined symbol contains a quantifier.
if(has_quantifier(prepared_expr))
{
out << "(declare-fun ";
convert_literal(l);
out << " () Bool)\n";
out << "(assert (= ";
convert_literal(l);
out << ' ';
convert_expr(prepared_expr);
out << "))\n";
}
else
{
auto identifier =
convert_identifier(std::string{"B"} + std::to_string(l.var_no()));
defined_expressions[expr] = identifier;
smt2_identifiers.insert(identifier);
out << "(define-fun " << identifier << " () Bool ";
convert_expr(prepared_expr);
out << ")\n";
}
return l;
}
exprt smt2_convt::handle(const exprt &expr)
{
// We can only improve Booleans.
if(!expr.is_boolean())
return expr;
return literal_exprt(convert(expr));
}
void smt2_convt::convert_literal(const literalt l)
{
if(l==const_literal(false))
out << "false";
else if(l==const_literal(true))
out << "true";
else
{
if(l.sign())
out << "(not ";
const auto identifier =
convert_identifier("B" + std::to_string(l.var_no()));
out << identifier;
if(l.sign())
out << ")";
smt2_identifiers.insert(identifier);
}
}
void smt2_convt::push()
{
UNIMPLEMENTED;
}
void smt2_convt::push(const std::vector<exprt> &_assumptions)
{
INVARIANT(assumptions.empty(), "nested contexts are not supported");
assumptions = _assumptions;
}
void smt2_convt::pop()
{
assumptions.clear();
}
static bool is_smt2_simple_identifier(const std::string &identifier)
{
if(identifier.empty())