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Option to rewrite expression in term_graph

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Rewrite expressions to minimize uses of constants 0 and 1
Currently disabled due to interaction with quic
This commit is contained in:
Arie Gurfinkel 2017-12-22 23:15:10 -05:00
parent ecf9c629b0
commit 0c1ef7155a
1 changed files with 54 additions and 3 deletions
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57
src/muz/spacer/spacer_term_graph.cpp
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@ -115,10 +115,45 @@ public:
return true;
}
app* mk_le_zero(expr *arg) {
expr *e1, *e2, *e3;
// XXX currently disabled
if (false && m_arith.is_add(arg, e1, e2)) {
// e1-e2<=0 --> e1<=e2
if (m_arith.is_times_minus_one(e2, e3)) {
return m_arith.mk_le(e1, e3);
}
// -e1+e2<=0 --> e2<=e1
else if (m_arith.is_times_minus_one(e1, e3)) {
return m_arith.mk_le(e2, e3);
}
}
return m_arith.mk_le(arg, mk_zero());
}
app* mk_ge_zero(expr *arg) {
expr *e1, *e2, *e3;
// XXX currently disabled
if (false && m_arith.is_add(arg, e1, e2)) {
// e1-e2>=0 --> e1>=e2
if (m_arith.is_times_minus_one(e2, e3)) {
return m_arith.mk_ge(e1, e3);
}
// -e1+e2>=0 --> e2>=e1
else if (m_arith.is_times_minus_one(e1, e3)) {
return m_arith.mk_ge(e2, e3);
}
}
return m_arith.mk_ge(arg, mk_zero());
}
bool mk_le_core (expr *arg1, expr * arg2, app_ref &result) {
// t <= -1 ==> t < 0 ==> ! (t >= 0)
if (m_arith.is_int (arg1) && m_arith.is_minus_one (arg2)) {
result = m.mk_not (m_arith.mk_ge (arg1, mk_zero ()));
result = m.mk_not (mk_ge_zero (arg1));
return true;
}
else if (m_arith.is_zero(arg2)) {
result = mk_le_zero(arg1);
return true;
}
return false;
@ -133,15 +168,25 @@ public:
bool mk_ge_core (expr * arg1, expr * arg2, app_ref &result) {
// t >= 1 ==> t > 0 ==> ! (t <= 0)
if (m_arith.is_int (arg1) && is_one (arg2)) {
result = m.mk_not (m_arith.mk_le (arg1, mk_zero ()));
result = m.mk_not (mk_le_zero (arg1));
return true;
}
else if (m_arith.is_zero(arg2)) {
result = mk_ge_zero(arg1);
return true;
}
return false;
}
virtual app_ref process_lit (app *lit) {
virtual app_ref process_lit (app *_lit) {
app *lit = _lit;
expr *e1, *e2;
// strip negation
bool is_neg = m.is_not(lit);
if (is_neg) {
lit = to_app(to_app(lit)->get_arg(0));
}
app_ref res(m);
res = lit;
@ -154,6 +199,12 @@ public:
else if (m_arith.is_ge(lit, e1, e2)) {
mk_ge_core(e1, e2, res);
}
// restore negation
if (is_neg) {
res = m.mk_not(res);
}
return res;
}
};