add bv-size reduce #6137

- add option smt.bv.reduce_size.
  - it allows to apply incremental pre-processing of bit-vectors by identifying ranges that are known to be constant.
    This rewrite is beneficial, for instance, when bit-vectors are constrained to have many high-level bits set to 0.

src/smt/params/smt_params_helper.pyg

@@ -50,6 +50,7 @@ def_module_params(module_name='smt',
                           ('bv.watch_diseq', BOOL, False, 'use watch lists instead of eager axioms for bit-vectors'),
                           ('bv.delay', BOOL, True, 'delay internalize expensive bit-vector operations'),
                           ('bv.eq_axioms', BOOL, True, 'enable redundant equality axioms for bit-vectors'),
+                          ('bv.size_reduce', BOOL, False, 'turn assertions that set the upper bits of a bit-vector to constants into a substitution that replaces the bit-vector with constant bits. Useful for minimizing circuits as many input bits to circuits are constant'),
                           ('arith.random_initial_value', BOOL, False, 'use random initial values in the simplex-based procedure for linear arithmetic'),
                           ('arith.solver', UINT, 6, 'arithmetic solver: 0 - no solver, 1 - bellman-ford based solver (diff. logic only), 2 - simplex based solver, 3 - floyd-warshall based solver (diff. logic only) and no theory combination 4 - utvpi, 5 - infinitary lra, 6 - lra solver'),
                           ('arith.nl', BOOL, True, '(incomplete) nonlinear arithmetic support based on Groebner basis and interval propagation, relevant only if smt.arith.solver=2'),

src/smt/params/theory_bv_params.cpp

@@ -28,6 +28,7 @@ void theory_bv_params::updt_params(params_ref const & _p) {
     m_bv_enable_int2bv2int = p.bv_enable_int2bv(); 
     m_bv_delay = p.bv_delay();
     m_bv_eq_axioms = p.bv_eq_axioms();
+    m_bv_size_reduce = p.bv_size_reduce();
 }
 
 #define DISPLAY_PARAM(X) out << #X"=" << X << std::endl;
@@ -42,4 +43,5 @@ void theory_bv_params::display(std::ostream & out) const {
     DISPLAY_PARAM(m_bv_blast_max_size);
     DISPLAY_PARAM(m_bv_enable_int2bv2int);
     DISPLAY_PARAM(m_bv_delay);
+    DISPLAY_PARAM(m_bv_size_reduce);
 }

src/smt/params/theory_bv_params.h

@@ -36,6 +36,7 @@ struct theory_bv_params {
     bool         m_bv_enable_int2bv2int = true;
     bool         m_bv_watch_diseq = false;
     bool         m_bv_delay = true;
+    bool         m_bv_size_reduce = false;
     theory_bv_params(params_ref const & p = params_ref()) {
         updt_params(p);
     }