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extended calculation of info for regexes (#4656)
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* extended calculation of info for regexes, updated tracing of state_graph with regex info

* took care of PR comments and fixed some info calculation bugs

* fix rlimit for clang-10 (#4658)

* merge

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

* extended calculation of info for regexes, updated tracing of state_graph with regex info

* took care of PR comments and fixed some info calculation bugs

* added missing return statements, reordered def of compl to match declaration order of methods

* fixed loop lower bound bug in loop info and default nullable value in invalid_info

* fixed type bug: bool to lbool

* trying to remove invisible control characters

* renamed compl method (compl is a reserved c++ keyword) to complement

Co-authored-by: Arie Gurfinkel <arie.gurfinkel@uwaterloo.ca>
Co-authored-by: Nikolaj Bjorner <nbjorner@microsoft.com>
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@NikolajBjorner @agurfinkel
NikolajBjorner and agurfinkel authored Aug 22, 2020
2 parents 2d5b749 + 1e29ba7 commit db65381
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216 changes: 197 additions & 19 deletions src/ast/seq_decl_plugin.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1624,8 +1624,9 @@ seq_util::rex::info seq_util::rex::get_info_rec(expr* e) const {
if (result.is_valid())
return result;
if (!is_app(e))
return invalid_info;
result = mk_info_rec(to_app(e));
result = unknown_info;
else
result = mk_info_rec(to_app(e));
m_infos.setx(e->get_id(), result, invalid_info);
STRACE("re_info", tout << "compute_info(" << pp(u.re, e) << ")=" << result << std::endl;);
return result;
Expand All @@ -1637,67 +1638,244 @@ seq_util::rex::info seq_util::rex::get_info_rec(expr* e) const {
*/
seq_util::rex::info seq_util::rex::mk_info_rec(app* e) const {
info i1, i2;
lbool nullable(l_false);
unsigned min_length(0), lower_bound(0);
bool is_value(false);
bool normalized(false);
if (e->get_family_id() == u.get_family_id()) {
switch (e->get_decl()->get_decl_kind())
{
case OP_RE_EMPTY_SET:
return info(UINT_MAX);
return info(true, true, true, true, true, true, false, l_false, UINT_MAX, 0);
case OP_RE_FULL_SEQ_SET:
return info(true, true, true, true, true, true, false, l_true, 0, 1);
case OP_RE_STAR:
i1 = get_info_rec(e->get_arg(0));
return i1.star();
case OP_RE_OPTION:
return info(0);
i1 = get_info_rec(e->get_arg(0));
return i1.opt();
case OP_RE_RANGE:
case OP_RE_FULL_CHAR_SET:
case OP_RE_OF_PRED:
return info(1);
//TBD: check if the character predicate contains uninterpreted symbols or is nonground or is unsat
//TBD: check if the range is unsat
return info(true, true, true, true, true, true, true, l_false, 1, 0);
case OP_RE_CONCAT:
i1 = get_info_rec(e->get_arg(0));
i2 = get_info_rec(e->get_arg(1));
return info(u.max_plus(i1.min_length, i2.min_length));
return i1.concat(i2, u.re.is_concat(e->get_arg(0)));
case OP_RE_UNION:
i1 = get_info_rec(e->get_arg(0));
i2 = get_info_rec(e->get_arg(1));
return info(std::min(i1.min_length, i2.min_length));
return i1.disj(i2);
case OP_RE_INTERSECT:
i1 = get_info_rec(e->get_arg(0));
i2 = get_info_rec(e->get_arg(1));
return info(std::max(i1.min_length, i2.min_length));
return i1.conj(i2);
case OP_SEQ_TO_RE:
return info(u.str.min_length(e->get_arg(0)));
min_length = u.str.min_length(e->get_arg(0));
is_value = m.is_value(e->get_arg(0));
nullable = (is_value && min_length == 0 ? l_true : (min_length > 0 ? l_false : l_undef));
return info(true, true, is_value, true, true, true, (min_length == 1 && u.str.max_length(e->get_arg(0)) == 1), nullable, min_length, 0);
case OP_RE_REVERSE:
case OP_RE_PLUS:
return get_info_rec(e->get_arg(0));
case OP_RE_PLUS:
i1 = get_info_rec(e->get_arg(0));
return i1.plus();
case OP_RE_COMPLEMENT:
return info(0);
i1 = get_info_rec(e->get_arg(0));
return i1.complement();
case OP_RE_LOOP:
i1 = get_info_rec(e->get_arg(0));
return info(u.max_mul(i1.min_length, e->get_decl()->get_parameter(0).get_int()));
lower_bound = e->get_decl()->get_parameter(0).get_int();
return i1.loop(lower_bound);
case OP_RE_DIFF:
i1 = get_info_rec(e->get_arg(0));
i2 = get_info_rec(e->get_arg(1));
return info(std::max(i1.min_length, i2.min_length > 0 ? 0 : UINT_MAX));
return i1.diff(i2);
}
return invalid_info;
return unknown_info;
}
expr* c, * t, * f;
if (u.m.is_ite(e, c, t, f)) {
i1 = get_info_rec(t);
i2 = get_info_rec(f);
return info(std::min(i1.min_length, i2.min_length));
return i1.orelse(i2);
}
return invalid_info;
return unknown_info;
}

std::ostream& seq_util::rex::info::display(std::ostream& out) const {
if (valid)
out << "info(" << "min_length=" << min_length << ")";
if (is_known()) {
out << "info("
<< "nullable=" << (nullable == l_true ? "T" : (nullable == l_false ? "F" : "U")) << ", "
<< "classical=" << (classical ? "T" : "F") << ", "
<< "standard=" << (standard ? "T" : "F") << ", "
<< "nonbranching=" << (nonbranching ? "T" : "F") << ", "
<< "normalized=" << (normalized ? "T" : "F") << ", "
<< "monadic=" << (monadic ? "T" : "F") << ", "
<< "singleton=" << (singleton ? "T" : "F") << ", "
<< "min_length=" << min_length << ", "
<< "star_height=" << star_height << ")";
}
else if (is_valid())
out << "UNKNOWN";
else
out << "invalid_info";
out << "INVALID";
return out;
}

/*
String representation of the info.
*/
std::string seq_util::rex::info::str() const {
std::ostringstream out;
display(out);
return out.str();
}

seq_util::rex::info seq_util::rex::info::star() const {
//if is_known() is false then all mentioned properties will remain false
return seq_util::rex::info(classical, classical, interpreted, nonbranching, normalized, monadic, false, l_true, 0, star_height + 1);
}

seq_util::rex::info seq_util::rex::info::plus() const {
if (is_known()) {
//r+ is not normalized if r is nullable, the normalized form would be r*
return info(classical, classical, interpreted, nonbranching, (nullable == l_false ? normalized : false), monadic, false, nullable, min_length, star_height + 1);
}
else
return *this;
}

seq_util::rex::info seq_util::rex::info::opt() const {
//if is_known() is false then all mentioned properties will remain false
return seq_util::rex::info(classical, classical, interpreted, nonbranching, normalized, monadic, false, l_true, 0, star_height);
}

seq_util::rex::info seq_util::rex::info::complement() const {
if (is_known()) {
lbool compl_nullable = (nullable == l_true ? l_false : (nullable == l_false ? l_true : l_undef));
unsigned compl_min_length = (compl_nullable == l_false ? 1 : 0);
return info(false, standard, interpreted, nonbranching, normalized, monadic, false, compl_nullable, compl_min_length, star_height);
}
else
return *this;
}

seq_util::rex::info seq_util::rex::info::concat(seq_util::rex::info & rhs, bool lhs_is_concat) const {
if (is_known()) {
if (rhs.is_known()) {
unsigned m = min_length + rhs.min_length;
if (m < min_length || m < rhs.min_length)
m = UINT_MAX;
return info(classical & rhs.classical,
classical && rhs.classical, //both args of concat must be classical for it to be standard
interpreted && rhs.interpreted,
nonbranching && rhs.nonbranching,
(normalized && !lhs_is_concat && rhs.normalized),
monadic && rhs.monadic,
false,
((nullable == l_false || rhs.nullable == l_false) ? l_false : ((nullable == l_true && rhs.nullable == l_true) ? l_true : l_undef)),
m,
std::max(star_height, rhs.star_height));
}
else
return rhs;
}
else
return *this;
}

seq_util::rex::info seq_util::rex::info::disj(seq_util::rex::info& rhs) const {
if (is_known() || rhs.is_known()) {
//works correctly if one of the arguments is unknown
return info(classical & rhs.classical,
standard && rhs.standard,
interpreted && rhs.interpreted,
nonbranching && rhs.nonbranching,
normalized && rhs.normalized,
monadic && rhs.monadic,
singleton && rhs.singleton,
((nullable == l_true || rhs.nullable == l_true) ? l_true : ((nullable == l_false && rhs.nullable == l_false) ? l_false : l_undef)),
std::min(min_length, rhs.min_length),
std::max(star_height, rhs.star_height));
}
else
return rhs;
}

seq_util::rex::info seq_util::rex::info::conj(seq_util::rex::info& rhs) const {
if (is_known()) {
if (rhs.is_known()) {
return info(false,
standard && rhs.standard,
interpreted && rhs.interpreted,
nonbranching && rhs.nonbranching,
normalized && rhs.normalized,
monadic && rhs.monadic,
singleton && rhs.singleton,
((nullable == l_true && rhs.nullable == l_true) ? l_true : ((nullable == l_false || rhs.nullable == l_false) ? l_false : l_undef)),
std::max(min_length, rhs.min_length),
std::max(star_height, rhs.star_height));
}
else
return rhs;
}
else
return *this;
}

seq_util::rex::info seq_util::rex::info::diff(seq_util::rex::info& rhs) const {
if (is_known()) {
if (rhs.is_known()) {
return info(false,
standard & rhs.standard,
interpreted & rhs.interpreted,
nonbranching & rhs.nonbranching,
normalized & rhs.normalized,
monadic & rhs.monadic,
false,
((nullable == l_true && rhs.nullable == l_false) ? l_true : ((nullable == l_false || rhs.nullable == l_false) ? l_false : l_undef)),
std::max(min_length, rhs.min_length),
std::max(star_height, rhs.star_height));
}
else
return rhs;
}
else
return *this;
}

seq_util::rex::info seq_util::rex::info::orelse(seq_util::rex::info& i) const {
if (is_known()) {
if (i.is_known()) {
unsigned ite_min_length = std::min(min_length, i.min_length);
lbool ite_nullable = (nullable == i.nullable ? nullable : l_undef);
//TBD: whether ite is interpreted or not depends on whether the condition is interpreted and both branches are interpreted
return info(false, false, false, false, normalized && i.normalized, monadic && i.monadic, singleton && i.singleton, nullable, min_length, std::max(star_height, i.star_height));
}
else
return i;
}
else
return *this;
}

seq_util::rex::info seq_util::rex::info::loop(unsigned lower) const {
if (is_known()) {
//r{l,m} is not normalized if r is nullable but l > 0
unsigned m = min_length * lower;
if (m > 0 && (m < min_length || m < lower))
m = UINT_MAX;
bool loop_normalized = (nullable == l_false && lower > 0 ? false : normalized);
lbool loop_nullable = (nullable == l_true || lower == 0 ? l_true : nullable);
//TBD: pass also upper bound and if upper bound is UINT_MAX then this is * and the loop is thus not normalized
return info(classical, classical, interpreted, nonbranching, loop_normalized, singleton, false, loop_nullable, m, star_height);
}
else
return *this;
}


82 changes: 76 additions & 6 deletions src/ast/seq_decl_plugin.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ Revision History:
#include "ast/ast.h"
#include "ast/bv_decl_plugin.h"
#include <string>
#include "util/lbool.h"

#define Z3_USE_UNICODE 0

Expand Down Expand Up @@ -411,21 +412,89 @@ class seq_util {
class rex {
public:
struct info {
bool valid;
unsigned min_length;
info() : valid(false), min_length(0) {}
info(unsigned k) : valid(true), min_length(k) {}
bool is_valid() { return valid; }
/* Value is either undefined (known=l_undef) or defined and known (l_true) or defined but unknown (l_false)*/
lbool known{ l_undef };
/* No complement, no intersection, no difference, and no if-then-else is used. Reverse is allowed. */
bool classical{ false };
/* Boolean-reverse combination of classical regexes (using reverse, union, complement, intersection or difference). */
bool standard{ false };
/* There are no uninterpreted symbols. */
bool interpreted{ false };
/* No if-then-else is used. */
bool nonbranching{ false };
/* Concatenations are right associative and if a loop body is nullable then the lower bound is zero. */
bool normalized{ false };
/* All bounded loops have a body that is a singleton. */
bool monadic{ false };
/* Positive Boolean combination of ranges or predicates or singleton sequences. */
bool singleton{ false };
/* If l_true then empty word is accepted, if l_false then empty word is not accepted. */
lbool nullable{ l_undef };
/* Lower bound on the length of all accepted words. */
unsigned min_length{ 0 };
/* Maximum nesting depth of Kleene stars. */
unsigned star_height{ 0 };

/*
Default constructor of invalid info.
*/
info() {}

/*
Used for constructing either an invalid info that is only used to indicate uninitialzed entry, or valid but unknown info value.
*/
info(lbool is_known) : known(is_known) {}

/*
General info constructor.
*/
info(bool is_classical,
bool is_standard,
bool is_interpreted,
bool is_nonbranching,
bool is_normalized,
bool is_monadic,
bool is_singleton,
lbool is_nullable,
unsigned min_l,
unsigned star_h) :
known(l_true), classical(is_classical), standard(is_standard), interpreted(is_interpreted), nonbranching(is_nonbranching),
normalized(is_normalized), monadic(is_monadic), singleton(is_singleton), nullable(is_nullable),
min_length(min_l), star_height(star_h) {}

/*
Appends a string representation of the info into the stream.
*/
std::ostream& display(std::ostream&) const;

/*
Returns a string representation of the info.
*/
std::string str() const;

bool is_valid() const { return known != l_undef; }

bool is_known() const { return known == l_true; }

info star() const;
info plus() const;
info opt() const;
info complement() const;
info concat(info & rhs, bool lhs_is_concat) const;
info disj(info& rhs) const;
info conj(info& rhs) const;
info diff(info& rhs) const;
info orelse(info& rhs) const;
info loop(unsigned lower) const;
};
private:
seq_util& u;
ast_manager& m;
family_id m_fid;
vector<info> mutable m_infos;
expr_ref_vector mutable m_info_pinned;
info invalid_info;
info invalid_info{ info(l_undef) };
info unknown_info{ info(l_false) };

bool has_valid_info(expr* r) const;
info get_info_rec(expr* r) const;
Expand Down Expand Up @@ -536,3 +605,4 @@ class seq_util {
inline std::ostream& operator<<(std::ostream& out, seq_util::rex::pp const & p) { return p.display(out); }

inline std::ostream& operator<<(std::ostream& out, seq_util::rex::info const& p) { return p.display(out); }

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