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
}
char *Z3SolverImpl::getConstraintLog(const Query &query) {
std::vector<Z3ASTHandle> assumptions;
// We use a different builder here because we don't want to interfere
// with the solver's builder because it may change the solver builder's
// cache.
// NOTE: The builder does not set `z3LogInteractionFile` to avoid conflicting
// with whatever the solver's builder is set to do.
Z3Builder temp_builder(/*autoClearConstructCache=*/false,
/*z3LogInteractionFile=*/NULL);
for (std::vector<ref<Expr> >::const_iterator it = query.constraints.begin(),
ie = query.constraints.end();
it != ie; ++it) {
assumptions.push_back(temp_builder.construct(*it));
}
::Z3_ast *assumptionsArray = NULL;
int numAssumptions = query.constraints.size();
if (numAssumptions) {
assumptionsArray = (::Z3_ast *)malloc(sizeof(::Z3_ast) * numAssumptions);
for (int index = 0; index < numAssumptions; ++index) {
assumptionsArray[index] = (::Z3_ast)assumptions[index];
}
}
// KLEE Queries are validity queries i.e.
// ∀ X Constraints(X) → query(X)
// but Z3 works in terms of satisfiability so instead we ask the
// the negation of the equivalent i.e.
// ∃ X Constraints(X) ∧ ¬ query(X)
Z3ASTHandle formula = Z3ASTHandle(
Z3_mk_not(temp_builder.ctx, temp_builder.construct(query.expr)),
temp_builder.ctx);
::Z3_string result = Z3_benchmark_to_smtlib_string(
temp_builder.ctx,
/*name=*/"Emited by klee::Z3SolverImpl::getConstraintLog()",
/*logic=*/"",
/*status=*/"unknown",
/*attributes=*/"",
/*num_assumptions=*/numAssumptions,
/*assumptions=*/assumptionsArray,
/*formula=*/formula);
if (numAssumptions)
free(assumptionsArray);
// We need to trigger a dereference before the `temp_builder` gets destroyed.
// We do this indirectly by emptying `assumptions` and assigning to
// `formula`.
assumptions.clear();
formula = Z3ASTHandle(NULL, temp_builder.ctx);
// Client is responsible for freeing the returned C-string
return strdup(result);
}
bool Z3SolverImpl::validateZ3Model(::Z3_solver &theSolver, ::Z3_model &theModel) {
bool success = true;
::Z3_ast_vector constraints =
Z3_solver_get_assertions(builder->ctx, theSolver);
Z3_ast_vector_inc_ref(builder->ctx, constraints);
unsigned size = Z3_ast_vector_size(builder->ctx, constraints);
for (unsigned index = 0; index < size; ++index) {
Z3ASTHandle constraint = Z3ASTHandle(
Z3_ast_vector_get(builder->ctx, constraints, index), builder->ctx);
::Z3_ast rawEvaluatedExpr;
bool successfulEval =
Z3_model_eval(builder->ctx, theModel, constraint,
/*model_completion=*/Z3_TRUE, &rawEvaluatedExpr);
assert(successfulEval && "Failed to evaluate model");
// Use handle to do ref-counting.
Z3ASTHandle evaluatedExpr(rawEvaluatedExpr, builder->ctx);
Z3SortHandle sort =
Z3SortHandle(Z3_get_sort(builder->ctx, evaluatedExpr), builder->ctx);
assert(Z3_get_sort_kind(builder->ctx, sort) == Z3_BOOL_SORT &&
"Evaluated expression has wrong sort");
Z3_lbool evaluatedValue =
Z3_get_bool_value(builder->ctx, evaluatedExpr);
if (evaluatedValue != Z3_L_TRUE) {
llvm::errs() << "Validating model failed:\n"
<< "The expression:\n";
constraint.dump();
llvm::errs() << "evaluated to \n";
evaluatedExpr.dump();
llvm::errs() << "But should be true\n";
success = false;
}
}
if (!success) {
llvm::errs() << "Solver state:\n" << Z3_solver_to_string(builder->ctx, theSolver) << "\n";
llvm::errs() << "Model:\n" << Z3_model_to_string(builder->ctx, theModel) << "\n";
}
Z3_ast_vector_dec_ref(builder->ctx, constraints);
return success;
}
char *Z3SolverImpl::getConstraintLog(const Query &query) {
std::vector<Z3ASTHandle> assumptions;
for (std::vector<ref<Expr> >::const_iterator it = query.constraints.begin(),
ie = query.constraints.end();
it != ie; ++it) {
assumptions.push_back(builder->construct(*it));
}
::Z3_ast *assumptionsArray = NULL;
int numAssumptions = query.constraints.size();
if (numAssumptions) {
assumptionsArray = (::Z3_ast *)malloc(sizeof(::Z3_ast) * numAssumptions);
for (int index = 0; index < numAssumptions; ++index) {
assumptionsArray[index] = (::Z3_ast)assumptions[index];
}
}
// KLEE Queries are validity queries i.e.
// ∀ X Constraints(X) → query(X)
// but Z3 works in terms of satisfiability so instead we ask the
// the negation of the equivalent i.e.
// ∃ X Constraints(X) ∧ ¬ query(X)
Z3ASTHandle formula = Z3ASTHandle(
Z3_mk_not(builder->ctx, builder->construct(query.expr)), builder->ctx);
::Z3_string result = Z3_benchmark_to_smtlib_string(
builder->ctx,
/*name=*/"Emited by klee::Z3SolverImpl::getConstraintLog()",
/*logic=*/"",
/*status=*/"unknown",
/*attributes=*/"",
/*num_assumptions=*/numAssumptions,
/*assumptions=*/assumptionsArray,
/*formula=*/formula);
if (numAssumptions)
free(assumptionsArray);
// Client is responsible for freeing the returned C-string
return strdup(result);
}
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
}