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https://github.com/Z3Prover/z3
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125 lines
3.3 KiB
C++
125 lines
3.3 KiB
C++
/*++
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Copyright (c) 2006 Microsoft Corporation
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Module Name:
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maximise_ac_sharing.h
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Abstract:
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<abstract>
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Author:
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Leonardo de Moura (leonardo) 2008-10-22.
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Revision History:
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--*/
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#ifndef _MAXIMISE_AC_SHARING_H_
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#define _MAXIMISE_AC_SHARING_H_
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#include"simplifier.h"
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#include"hashtable.h"
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#include"bv_decl_plugin.h"
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#include"region.h"
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/**
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\brief Functor used to maximise the amount of shared terms in an expression.
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The idea is to rewrite AC terms to maximise sharing.
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Example:
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(f (bvadd a (bvadd b c)) (bvadd a (bvadd b d)))
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is rewritten to:
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(f (bvadd (bvadd a b) c) (bvadd (bvadd a b) d))
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\warning This class uses an opportunistic heuristic to maximise sharing.
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There is no guarantee that the optimal expression will be produced.
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*/
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class maximise_ac_sharing {
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struct entry {
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func_decl * m_decl;
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expr * m_arg1;
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expr * m_arg2;
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entry(func_decl * d = 0, expr * arg1 = 0, expr * arg2 = 0):m_decl(d), m_arg1(arg1), m_arg2(arg2) {
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SASSERT((d == 0 && arg1 == 0 && arg2 == 0) || (d != 0 && arg1 != 0 && arg2 != 0));
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if (arg1->get_id() > arg2->get_id())
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std::swap(m_arg1, m_arg2);
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}
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unsigned hash() const {
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unsigned a = m_decl->get_id();
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unsigned b = m_arg1->get_id();
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unsigned c = m_arg2->get_id();
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mix(a,b,c);
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return c;
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}
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bool operator==(entry const & e) const {
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return m_decl == e.m_decl && m_arg1 == e.m_arg1 && m_arg2 == e.m_arg2;
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}
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};
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typedef ptr_hashtable<entry, obj_ptr_hash<entry>, deref_eq<entry> > cache;
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protected:
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class ac_plugin : public simplifier_plugin {
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maximise_ac_sharing & m_owner;
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svector<decl_kind> m_kinds; //!< kinds to be processed
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public:
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ac_plugin(symbol const & fname, ast_manager & m, maximise_ac_sharing & owner);
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void register_kind(decl_kind k);
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virtual ~ac_plugin();
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virtual bool reduce(func_decl * f, unsigned num_args, expr * const * args, expr_ref & result);
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};
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friend class ac_plugin;
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private:
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ast_manager & m_manager;
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simplifier m_simplifier;
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bool m_init;
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region m_region;
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cache m_cache;
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ptr_vector<entry> m_entries;
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unsigned_vector m_scopes;
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bool contains(func_decl * f, expr * arg1, expr * arg2);
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void insert(func_decl * f, expr * arg1, expr * arg2);
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void restore_entries(unsigned old_lim);
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void init() {
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if (!m_init) {
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init_core();
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m_init = true;
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}
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}
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protected:
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virtual void init_core() = 0;
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virtual bool is_numeral(expr * n) const = 0;
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void register_plugin(ac_plugin * p) { m_simplifier.register_plugin(p); }
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public:
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maximise_ac_sharing(ast_manager & m);
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virtual ~maximise_ac_sharing();
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void operator()(expr * s, expr_ref & r, proof_ref & p);
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void push_scope();
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void pop_scope(unsigned num_scopes);
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void reset();
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ast_manager & get_manager() { return m_manager; }
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};
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class maximise_bv_sharing : public maximise_ac_sharing {
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bv_util m_util;
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protected:
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virtual void init_core();
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virtual bool is_numeral(expr * n) const;
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public:
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maximise_bv_sharing(ast_manager & m);
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};
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#endif /* _MAXIMISE_AC_SHARING_H_ */
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