bool Z3SolverImpl::internalRunSolver(
const Query &query, const std::vector<const Array *> *objects,
std::vector<std::vector<unsigned char> > *values, bool &hasSolution) {
TimerStatIncrementer t(stats::queryTime);
// TODO: Does making a new solver for each query have a performance
// impact vs making one global solver and using push and pop?
// TODO: is the "simple_solver" the right solver to use for
// best performance?
Z3_solver theSolver = Z3_mk_simple_solver(builder->ctx);
Z3_solver_inc_ref(builder->ctx, theSolver);
Z3_solver_set_params(builder->ctx, theSolver, solverParameters);
runStatusCode = SOLVER_RUN_STATUS_FAILURE;
for (ConstraintManager::const_iterator it = query.constraints.begin(),
ie = query.constraints.end();
it != ie; ++it) {
Z3_solver_assert(builder->ctx, theSolver, builder->construct(*it));
}
++stats::queries;
if (objects)
++stats::queryCounterexamples;
Z3ASTHandle z3QueryExpr =
Z3ASTHandle(builder->construct(query.expr), builder->ctx);
// KLEE Queries are validity queries i.e.
// ∀ X Constraints(X) → query(X)
// but Z3 works in terms of satisfiability so instead we ask the
// negation of the equivalent i.e.
// ∃ X Constraints(X) ∧ ¬ query(X)
Z3_solver_assert(
builder->ctx, theSolver,
Z3ASTHandle(Z3_mk_not(builder->ctx, z3QueryExpr), builder->ctx));
::Z3_lbool satisfiable = Z3_solver_check(builder->ctx, theSolver);
runStatusCode = handleSolverResponse(theSolver, satisfiable, objects, values,
hasSolution);
Z3_solver_dec_ref(builder->ctx, theSolver);
// Clear the builder's cache to prevent memory usage exploding.
// By using ``autoClearConstructCache=false`` and clearning now
// we allow Z3_ast expressions to be shared from an entire
// ``Query`` rather than only sharing within a single call to
// ``builder->construct()``.
builder->clearConstructCache();
if (runStatusCode == SolverImpl::SOLVER_RUN_STATUS_SUCCESS_SOLVABLE ||
runStatusCode == SolverImpl::SOLVER_RUN_STATUS_SUCCESS_UNSOLVABLE) {
if (hasSolution) {
++stats::queriesInvalid;
} else {
++stats::queriesValid;
}
return true; // success
}
return false; // failed
}
static void tst_get_implied_equalities1() {
Z3_config cfg = Z3_mk_config();
Z3_context ctx = Z3_mk_context(cfg);
Z3_del_config(cfg);
Z3_sort int_ty = Z3_mk_int_sort(ctx);
Z3_ast a = mk_int_var(ctx,"a");
Z3_ast b = mk_int_var(ctx,"b");
Z3_ast c = mk_int_var(ctx,"c");
Z3_ast d = mk_int_var(ctx,"d");
Z3_func_decl f = Z3_mk_func_decl(ctx, Z3_mk_string_symbol(ctx,"f"), 1, &int_ty, int_ty);
Z3_ast fa = Z3_mk_app(ctx, f, 1, &a);
Z3_ast fb = Z3_mk_app(ctx, f, 1, &b);
Z3_ast fc = Z3_mk_app(ctx, f, 1, &c);
unsigned const num_terms = 7;
unsigned i;
Z3_ast terms[7] = { a, b, c, d, fa, fb, fc };
unsigned class_ids[7] = { 0, 0, 0, 0, 0, 0, 0 };
Z3_solver solver = Z3_mk_simple_solver(ctx);
Z3_solver_inc_ref(ctx, solver);
Z3_solver_assert(ctx, solver, Z3_mk_eq(ctx, a, b));
Z3_solver_assert(ctx, solver, Z3_mk_eq(ctx, b, d));
Z3_solver_assert(ctx, solver, Z3_mk_le(ctx, fa, fc));
Z3_solver_assert(ctx, solver, Z3_mk_le(ctx, fc, d));
Z3_get_implied_equalities(ctx, solver, num_terms, terms, class_ids);
for (i = 0; i < num_terms; ++i) {
printf("Class %s |-> %d\n", Z3_ast_to_string(ctx, terms[i]), class_ids[i]);
}
SASSERT(class_ids[1] == class_ids[0]);
SASSERT(class_ids[2] != class_ids[0]);
SASSERT(class_ids[3] == class_ids[0]);
SASSERT(class_ids[4] != class_ids[0]);
SASSERT(class_ids[5] != class_ids[0]);
SASSERT(class_ids[6] != class_ids[0]);
SASSERT(class_ids[4] == class_ids[5]);
printf("asserting b <= f(a)\n");
Z3_solver_assert(ctx, solver, Z3_mk_le(ctx, b, fa));
Z3_get_implied_equalities(ctx, solver, num_terms, terms, class_ids);
for (i = 0; i < num_terms; ++i) {
printf("Class %s |-> %d\n", Z3_ast_to_string(ctx, terms[i]), class_ids[i]);
}
SASSERT(class_ids[1] == class_ids[0]);
SASSERT(class_ids[2] != class_ids[0]);
SASSERT(class_ids[3] == class_ids[0]);
SASSERT(class_ids[4] == class_ids[0]);
SASSERT(class_ids[5] == class_ids[0]);
SASSERT(class_ids[6] == class_ids[0]);
Z3_solver_dec_ref(ctx, solver);
/* delete logical context */
Z3_del_context(ctx);
}
/**
\brief Finds the maximal number of assumptions that can be satisfied.
An assumption is any formula preceded with the :assumption keyword.
"Hard" constraints can be supported by using the :formula keyword.
Input: file in SMT-LIB format, and MaxSAT algorithm to be used: 0 - Naive, 1 - Fu&Malik's algo.
Output: the maximum number of assumptions that can be satisfied.
*/
int smtlib_maxsat(char * file_name, int approach)
{
Z3_context ctx;
Z3_solver s;
unsigned i;
Z3_optimize opt;
unsigned num_hard_cnstrs, num_soft_cnstrs;
Z3_ast * hard_cnstrs, * soft_cnstrs;
Z3_ast_vector hard, objs;
Z3_app soft;
unsigned result = 0;
ctx = mk_context();
s = mk_solver(ctx);
opt = Z3_mk_optimize(ctx);
Z3_optimize_inc_ref(ctx, opt);
Z3_optimize_from_file(ctx, opt, file_name);
hard = Z3_optimize_get_assertions(ctx, opt);
Z3_ast_vector_inc_ref(ctx, hard);
num_hard_cnstrs = Z3_ast_vector_size(ctx, hard);
hard_cnstrs = (Z3_ast *) malloc(sizeof(Z3_ast) * (num_hard_cnstrs));
for (i = 0; i < num_hard_cnstrs; i++) {
hard_cnstrs[i] = Z3_ast_vector_get(ctx, hard, i);
}
objs = Z3_optimize_get_objectives(ctx, opt);
Z3_ast_vector_inc_ref(ctx, objs);
// soft constraints are stored in a single objective which is a sum
// of if-then-else expressions.
soft = Z3_to_app(ctx, Z3_ast_vector_get(ctx, objs, 0));
num_soft_cnstrs = Z3_get_app_num_args(ctx, soft);
soft_cnstrs = (Z3_ast *) malloc(sizeof(Z3_ast) * (num_soft_cnstrs));
for (i = 0; i < num_soft_cnstrs; ++i) {
soft_cnstrs[i] = Z3_get_app_arg(ctx, Z3_to_app(ctx, Z3_get_app_arg(ctx, soft, i)), 0);
}
switch (approach) {
case NAIVE_MAXSAT:
result = naive_maxsat(ctx, s, num_hard_cnstrs, hard_cnstrs, num_soft_cnstrs, soft_cnstrs);
break;
case FU_MALIK_MAXSAT:
result = fu_malik_maxsat(ctx, s, num_hard_cnstrs, hard_cnstrs, num_soft_cnstrs, soft_cnstrs);
break;
default:
/* Exercise: implement your own MaxSAT algorithm.*/
error("Not implemented yet.");
break;
}
free_cnstr_array(hard_cnstrs);
free_cnstr_array(soft_cnstrs);
Z3_solver_dec_ref(ctx, s);
Z3_optimize_dec_ref(ctx, opt);
return result;
}
/**
\brief Small test for the at-most-one constraint.
*/
void tst_at_most_one()
{
Z3_context ctx = mk_context();
Z3_solver s = mk_solver(ctx);
Z3_ast k1 = mk_bool_var(ctx, "k1");
Z3_ast k2 = mk_bool_var(ctx, "k2");
Z3_ast k3 = mk_bool_var(ctx, "k3");
Z3_ast k4 = mk_bool_var(ctx, "k4");
Z3_ast k5 = mk_bool_var(ctx, "k5");
Z3_ast k6 = mk_bool_var(ctx, "k6");
Z3_ast args1[5] = { k1, k2, k3, k4, k5 };
Z3_ast args2[3] = { k4, k5, k6 };
Z3_model m = 0;
Z3_lbool result;
printf("testing at-most-one constraint\n");
assert_at_most_one(ctx, s, 5, args1);
assert_at_most_one(ctx, s, 3, args2);
printf("it must be sat...\n");
result = Z3_solver_check(ctx, s);
if (result != Z3_L_TRUE)
error("BUG");
m = Z3_solver_get_model(ctx, s);
Z3_model_inc_ref(ctx, m);
printf("model:\n%s\n", Z3_model_to_string(ctx, m));
Z3_model_dec_ref(ctx, m);
Z3_solver_assert(ctx, s, mk_binary_or(ctx, k2, k3));
Z3_solver_assert(ctx, s, mk_binary_or(ctx, k1, k6));
printf("it must be sat...\n");
result = Z3_solver_check(ctx, s);
if (result != Z3_L_TRUE)
error("BUG");
m = Z3_solver_get_model(ctx, s);
Z3_model_inc_ref(ctx, m);
printf("model:\n%s\n", Z3_model_to_string(ctx, m));
Z3_solver_assert(ctx, s, mk_binary_or(ctx, k4, k5));
printf("it must be unsat...\n");
result = Z3_solver_check(ctx, s);
if (result != Z3_L_FALSE)
error("BUG");
Z3_model_dec_ref(ctx, m);
Z3_solver_dec_ref(ctx, s);
Z3_del_context(ctx);
}
static void tst_get_implied_equalities2() {
enable_trace("after_search");
enable_trace("get_implied_equalities");
enable_trace("implied_equalities");
Z3_config cfg = Z3_mk_config();
Z3_context ctx = Z3_mk_context(cfg);
Z3_del_config(cfg);
Z3_solver solver = Z3_mk_simple_solver(ctx);
Z3_solver_inc_ref(ctx, solver);
Z3_sort int_ty = Z3_mk_int_sort(ctx);
Z3_ast a = mk_int_var(ctx,"a");
Z3_ast b = mk_int_var(ctx,"b");
Z3_ast one = Z3_mk_numeral(ctx, "1", int_ty);
Z3_ast two = Z3_mk_numeral(ctx, "2", int_ty);
Z3_ast x = Z3_mk_const_array(ctx, int_ty, one);
Z3_ast y = Z3_mk_store(ctx, x, one, a);
Z3_ast z = Z3_mk_store(ctx, y, two , b);
Z3_ast u = Z3_mk_store(ctx, x, two , b);
Z3_ast v = Z3_mk_store(ctx, u, one , a);
unsigned const num_terms = 5;
unsigned i;
Z3_ast terms[5] = { x, y, z, u, v};
unsigned class_ids[5] = { 0, 0, 0, 0, 0};
Z3_get_implied_equalities(ctx, solver, num_terms, terms, class_ids);
for (i = 0; i < num_terms; ++i) {
printf("Class %s |-> %d\n", Z3_ast_to_string(ctx, terms[i]), class_ids[i]);
}
SASSERT(class_ids[1] != class_ids[0]);
SASSERT(class_ids[2] != class_ids[0]);
SASSERT(class_ids[3] != class_ids[0]);
SASSERT(class_ids[4] != class_ids[0]);
SASSERT(class_ids[4] == class_ids[2]);
SASSERT(class_ids[2] != class_ids[1]);
SASSERT(class_ids[3] != class_ids[1]);
SASSERT(class_ids[4] != class_ids[1]);
SASSERT(class_ids[3] != class_ids[2]);
/* delete logical context */
Z3_solver_dec_ref(ctx, solver);
Z3_del_context(ctx);
}
Z3Solver::~Z3Solver()
{
if (Ctx != Z3Ctx::NullPtr && Solver != nullptr) {
Z3_solver_dec_ref(*Ctx, Solver);
}
}
void z3_wrapper_free(z3_wrapper *z3) {
Z3_solver_dec_ref(z3->ctx, z3->solver);
Z3_del_context(z3->ctx);
free(z3->Ek_consts);
}
bool Z3SolverImpl::internalRunSolver(
const Query &query, const std::vector<const Array *> *objects,
std::vector<std::vector<unsigned char> > *values, bool &hasSolution) {
TimerStatIncrementer t(stats::queryTime);
// NOTE: Z3 will switch to using a slower solver internally if push/pop are
// used so for now it is likely that creating a new solver each time is the
// right way to go until Z3 changes its behaviour.
//
// TODO: Investigate using a custom tactic as described in
// https://github.com/klee/klee/issues/653
Z3_solver theSolver = Z3_mk_solver(builder->ctx);
Z3_solver_inc_ref(builder->ctx, theSolver);
Z3_solver_set_params(builder->ctx, theSolver, solverParameters);
runStatusCode = SOLVER_RUN_STATUS_FAILURE;
for (ConstraintManager::const_iterator it = query.constraints.begin(),
ie = query.constraints.end();
it != ie; ++it) {
Z3_solver_assert(builder->ctx, theSolver, builder->construct(*it));
}
++stats::queries;
if (objects)
++stats::queryCounterexamples;
Z3ASTHandle z3QueryExpr =
Z3ASTHandle(builder->construct(query.expr), builder->ctx);
// KLEE Queries are validity queries i.e.
// ∀ X Constraints(X) → query(X)
// but Z3 works in terms of satisfiability so instead we ask the
// negation of the equivalent i.e.
// ∃ X Constraints(X) ∧ ¬ query(X)
Z3_solver_assert(
builder->ctx, theSolver,
Z3ASTHandle(Z3_mk_not(builder->ctx, z3QueryExpr), builder->ctx));
if (dumpedQueriesFile) {
*dumpedQueriesFile << "; start Z3 query\n";
*dumpedQueriesFile << Z3_solver_to_string(builder->ctx, theSolver);
*dumpedQueriesFile << "(check-sat)\n";
*dumpedQueriesFile << "(reset)\n";
*dumpedQueriesFile << "; end Z3 query\n\n";
dumpedQueriesFile->flush();
}
::Z3_lbool satisfiable = Z3_solver_check(builder->ctx, theSolver);
runStatusCode = handleSolverResponse(theSolver, satisfiable, objects, values,
hasSolution);
Z3_solver_dec_ref(builder->ctx, theSolver);
// Clear the builder's cache to prevent memory usage exploding.
// By using ``autoClearConstructCache=false`` and clearning now
// we allow Z3_ast expressions to be shared from an entire
// ``Query`` rather than only sharing within a single call to
// ``builder->construct()``.
builder->clearConstructCache();
if (runStatusCode == SolverImpl::SOLVER_RUN_STATUS_SUCCESS_SOLVABLE ||
runStatusCode == SolverImpl::SOLVER_RUN_STATUS_SUCCESS_UNSOLVABLE) {
if (hasSolution) {
++stats::queriesInvalid;
} else {
++stats::queriesValid;
}
return true; // success
}
return false; // failed
}
