Add new tactic bound-simplifier for integer-based bit-vector reasoning.

src/ast/simplifiers/bound_simplifier.h

@@ -0,0 +1,90 @@
+/*++
+Copyright (c) 2022 Microsoft Corporation
+
+Module Name:
+
+    bound_simplifier.h
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2023-01-22
+
+Description:
+
+    Collects bounds of sub-expressions and uses them to simplify modulus
+    expressions. 
+    propagate_ineqs_tactic handles other propagations with bounds.
+
+--*/
+
+#pragma once
+
+#include "ast/arith_decl_plugin.h"
+#include "ast/rewriter/th_rewriter.h"
+#include "ast/simplifiers/dependent_expr_state.h"
+#include "ast/simplifiers/bound_propagator.h"
+
+
+class bound_simplifier : public dependent_expr_simplifier {
+    arith_util              a;
+    th_rewriter             m_rewriter;
+    unsynch_mpq_manager     nm;
+    small_object_allocator  m_alloc;
+    bound_propagator        bp;
+    unsigned                m_num_vars = 0;
+    ptr_vector<expr>        m_var2expr;
+    unsigned_vector         m_expr2var;
+    bool                    m_updated = false;
+
+    struct rw_cfg;
+    struct rw;
+   
+    bool insert_bound(dependent_expr const& de);
+    void tighten_bound(dependent_expr const& de);
+
+    void reset();
+
+    expr* to_expr(unsigned v) const { 
+        return m_var2expr.get(v, nullptr); 
+    }
+
+    bool is_var(expr* e) const {
+        return UINT_MAX != m_expr2var.get(e->get_id(), UINT_MAX);
+    }
+
+    unsigned to_var(expr* e) { 
+        unsigned v = m_expr2var.get(e->get_id(), UINT_MAX); 
+        if (v == UINT_MAX) {
+            v = m_num_vars++;
+            bp.mk_var(v, a.is_int(e));
+            m_expr2var.setx(e->get_id(), v, UINT_MAX);
+            m_var2expr.setx(v, e, nullptr);
+        }
+        return v;
+    }
+
+    void assert_lower(expr* x, rational const& n, bool strict);
+    void assert_upper(expr* x, rational const& n, bool strict);
+
+    bool has_upper(expr* x, rational& n, bool& strict);
+    bool has_lower(expr* x, rational& n, bool& strict);
+
+    // e = x + offset
+    bool is_offset(expr* e, expr* x, rational& offset);
+
+public:
+
+    bound_simplifier(ast_manager& m, params_ref const& p, dependent_expr_state& fmls):
+        dependent_expr_simplifier(m, fmls),
+        a(m),
+        m_rewriter(m),
+        bp(nm, m_alloc, p) {
+    }
+
+    char const* name() const override { return "bounds-simplifier"; }
+      
+    bool supports_proofs() const override { return false; }
+
+    void reduce() override;
+};
+