add demodulator simplifier

refactor demodulator-rewriter a bit to separate reusable features.

src/ast/simplifiers/demodulator_simplifier.h

@@ -0,0 +1,60 @@
+/*++
+Copyright (c) 2022 Microsoft Corporation
+
+Module Name:
+
+    demodulator_simplifier.h
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2022-12-4
+
+--*/
+
+#pragma once
+
+#include "ast/substitution/demodulator_rewriter.h"
+#include "ast/simplifiers/dependent_expr_state.h"
+#include "util/uint_set.h"
+
+class demodulator_index {
+    obj_map<func_decl, uint_set*> m_fwd_index, m_bwd_index; 
+    void add(func_decl* f, unsigned i, obj_map<func_decl, uint_set*>& map);
+    void del(func_decl* f, unsigned i, obj_map<func_decl, uint_set*>& map);
+ public:
+    ~demodulator_index();
+    void reset();
+    void insert_fwd(func_decl* f, unsigned i) { add(f, i, m_fwd_index); }
+    void remove_fwd(func_decl* f, unsigned i) { del(f, i, m_fwd_index); }
+    void insert_bwd(expr* e, unsigned i);
+    void remove_bwd(expr* e, unsigned i);
+    bool find_fwd(func_decl* f, uint_set*& s) { return m_bwd_index.find(f, s); }
+    bool find_bwd(func_decl* f, uint_set*& s) { return m_fwd_index.find(f, s); }
+    bool empty() const { return m_fwd_index.empty(); }
+};
+
+class demodulator_simplifier : public dependent_expr_simplifier {
+    typedef std::pair<app*, expr*> app_expr_pair;
+    demodulator_index         m_index;
+    demodulator_util          m_util;
+    demodulator_match_subst   m_match_subst;
+    demodulator_rewriter_util m_rewriter;
+    u_map<app_expr_pair>      m_rewrites;
+    uint_set                  m_processed, m_dependencies;
+    unsigned_vector           m_todo;
+    expr_ref_vector           m_pinned;
+
+    void rewrite(unsigned i);
+    bool rewrite1(func_decl* f, expr_ref_vector const& args, expr_ref& np);
+    expr* fml(unsigned i) { return m_fmls[i].fml(); }
+    expr_dependency* dep(unsigned i) { return m_fmls[i].dep(); }
+    void reschedule_processed(func_decl* f);
+    void reschedule_demodulators(func_decl* f, expr* lhs);
+    void reset();
+
+ public:
+     demodulator_simplifier(ast_manager& m, params_ref const& p, dependent_expr_state& st);
+     void reduce() override;
+
+    
+};