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This commit is contained in:
Leonardo Alt
2020-07-23 18:49:03 +02:00
parent 003c9b9a5b
commit 5bb4e73693
10 changed files with 40 additions and 86 deletions
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libsmtutil/Z3CHCInterface.cpp
+15 -27
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@@ -36,7 +36,7 @@ Z3CHCInterface::Z3CHCInterface():
z3::set_param("rewriter.pull_cheap_ite", true);
z3::set_param("rlimit", Z3Interface::resourceLimit);
enablePreProcessing();
setSpacerOptions();
}
void Z3CHCInterface::declareVariable(string const& _name, SortPointer const& _sort)
@@ -104,7 +104,7 @@ pair<CheckResult, CHCSolverInterface::CexGraph> Z3CHCInterface::query(Expression
return {result, cex};
}
void Z3CHCInterface::enablePreProcessing()
void Z3CHCInterface::setSpacerOptions(bool _preProcessing)
{
// Spacer options.
// These needs to be set in the solver.
@@ -117,31 +117,12 @@ void Z3CHCInterface::enablePreProcessing()
// Ground pobs by using values from a model.
p.set("fp.spacer.ground_pobs", false);
// Enable Spacer optimization for better solving.
p.set("fp.xform.slice", true);
p.set("fp.xform.inline_linear", true);
p.set("fp.xform.inline_eager", true);
m_solver.set(p);
}
void Z3CHCInterface::disablePreProcessing()
{
// Spacer options.
// These needs to be set in the solver.
// https://github.com/Z3Prover/z3/blob/master/src/muz/base/fp_params.pyg
z3::params p(*m_context);
// These are useful for solving problems with arrays and loops.
// Use quantified lemma generalizer.
p.set("fp.spacer.q3.use_qgen", true);
p.set("fp.spacer.mbqi", false);
// Ground pobs by using values from a model.
p.set("fp.spacer.ground_pobs", false);
// Disable Spacer optimization for counterexample generation.
p.set("fp.xform.slice", false);
p.set("fp.xform.inline_linear", false);
p.set("fp.xform.inline_eager", false);
// Spacer optimization should be
// - enabled for better solving (default)
// - disable for counterexample generation
p.set("fp.xform.slice", _preProcessing);
p.set("fp.xform.inline_linear", _preProcessing);
p.set("fp.xform.inline_eager", _preProcessing);
m_solver.set(p);
}
@@ -151,6 +132,13 @@ Convert a ground refutation into a linear or nonlinear counterexample.
The counterexample is given as an implication graph of the form
`premises => conclusion` where `premises` are the predicates
from the body of nonlinear clauses, representing the proof graph.
This function is based on and similar to
https://github.com/Z3Prover/z3/blob/z3-4.8.8/src/muz/spacer/spacer_context.cpp#L2919
(spacer::context::get_ground_sat_answer)
which generates linear counterexamples.
It is modified here to accept nonlinear CHCs as well, generating a DAG
instead of a path.
*/
CHCSolverInterface::CexGraph Z3CHCInterface::cexGraph(z3::expr const& _proof)
{