adding pre-processing of BP constraints

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/ast/rewriter/pb_rewriter.cpp

@@ -18,6 +18,60 @@ Notes:
 --*/
 
 #include "pb_rewriter.h"
+#include "pb_rewriter_def.h"
+#include "ast_pp.h"
+
+
+class pb_ast_rewriter_util {
+    ast_manager& m;
+    expr_ref_vector m_refs;
+public:
+
+    typedef std::pair<expr*, rational> arg_t;
+    typedef vector<arg_t> args_t;
+    typedef rational numeral;
+
+    pb_ast_rewriter_util(ast_manager& m): m(m), m_refs(m) {}
+
+    expr* negate(expr* e) {
+        if (m.is_true(e)) {
+            return m.mk_false();
+        }
+        if (m.is_false(e)) {
+            return m.mk_true();
+        }
+        if (m.is_not(e, e)) {
+            return e;
+        }
+        m_refs.push_back(m.mk_not(e));
+        return m_refs.back();
+    }
+
+    void display(std::ostream& out, expr* e) {
+        out << mk_pp(e, m);
+    }
+
+    bool is_negated(expr* e) const {
+        return m.is_not(e);
+    }
+
+    bool is_true(expr* e) const {
+        return m.is_true(e);
+    }
+
+    bool is_false(expr* e) const {
+        return m.is_false(e);
+    }
+
+    struct compare {
+        bool operator()(std::pair<expr*,rational> const& a,
+                        std::pair<expr*,rational> const& b) {
+            return a.first->get_id() < b.first->get_id();
+        }
+
+    };
+};
+
 
 br_status pb_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * const * args, expr_ref & result) {
     ast_manager& m = result.get_manager();
@@ -32,34 +86,59 @@ br_status pb_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * cons
         }
     }
     rational k = m_util.get_k(f);
+
+    vector<std::pair<expr*,rational> > vec;
+    for (unsigned i = 0; i < num_args; ++i) {
+        vec.push_back(std::make_pair(args[i], m_util.get_coeff(f, i)));
+    }
     
     switch(f->get_decl_kind()) {
     case OP_AT_MOST_K:
     case OP_PB_LE:
-        if (sum > k) {
-            result = m.mk_false();
-            return BR_DONE;
+        for (unsigned i = 0; i < num_args; ++i) {
+            vec[i].second.neg();
         }
-        if (maxsum <= k) {
-            result = m.mk_true();
-            return BR_DONE;
-        }
-        return BR_FAILED;
+        k.neg();
+        break;
     case OP_AT_LEAST_K:
     case OP_PB_GE:
-        if (sum >= k) {
-            result = m.mk_true();
-            return BR_DONE;
-        }
-        if (maxsum < k) {
-            result = m.mk_false();
-            return BR_DONE;
-        }
-        return BR_FAILED;
+        break;
     default:
         UNREACHABLE();
         return BR_FAILED;
     }    
+
+    
+    pb_ast_rewriter_util pbu(m);
+    pb_rewriter_util<pb_ast_rewriter_util> util(pbu);
+
+    util.unique(vec, k);
+    lbool is_sat = util.normalize(vec, k);
+    util.prune(vec, k);
+    switch (is_sat) {
+    case l_true:
+        result = m.mk_true();
+        break;
+    case l_false:
+        result = m.mk_false();
+        break;
+    default:
+        m_args.reset();
+        m_coeffs.reset();
+        for (unsigned i = 0; i < vec.size(); ++i) {
+            m_args.push_back(vec[i].first);
+            m_coeffs.push_back(vec[i].second);
+        }
+        result = m_util.mk_ge(vec.size(), m_coeffs.c_ptr(), m_args.c_ptr(), k);
+        break;
+    }
+    TRACE("pb",
+          expr_ref tmp(m);
+          tmp = m.mk_app(f, num_args, args);
+          tout << tmp << "\n";
+          tout << result << "\n";);
+          
+    return BR_DONE;
 }