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strengthen simplification of to_int such that #1608 is handled during pre-processing

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2018-06-29 09:44:54 -07:00
parent 1e67717d75
commit cbc5aaad2c
1 changed files with 30 additions and 35 deletions
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65
src/ast/rewriter/arith_rewriter.cpp
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@ -1159,49 +1159,44 @@ br_status arith_rewriter::mk_to_int_core(expr * arg, expr_ref & result) {
result = m_util.mk_numeral(floor(a), true); result = m_util.mk_numeral(floor(a), true);
return BR_DONE; return BR_DONE;
} }
else if (m_util.is_to_real(arg, x)) {
if (m_util.is_to_real(arg, x)) {
result = x; result = x;
return BR_DONE; return BR_DONE;
} }
else {
if (m_util.is_add(arg) || m_util.is_mul(arg) || m_util.is_power(arg)) {
// Try to apply simplifications such as:
// (to_int (+ 1.0 (to_real x))) --> (+ 1 x)
// if all arguments of arg are if (m_util.is_add(arg) || m_util.is_mul(arg) || m_util.is_power(arg)) {
// - integer numerals, OR // Try to apply simplifications such as:
// - to_real applications // (to_int (+ 1.0 (to_real x)) y) --> (+ 1 x (to_int y))
// then, to_int can be eliminated
unsigned num_args = to_app(arg)->get_num_args(); expr_ref_buffer int_args(m()), real_args(m());
unsigned i = 0; for (expr* c : *to_app(arg)) {
for (; i < num_args; i++) { if (m_util.is_numeral(c, a) && a.is_int()) {
expr * c = to_app(arg)->get_arg(i); int_args.push_back(m_util.mk_numeral(a, true));
if (m_util.is_numeral(c, a) && a.is_int())
continue;
if (m_util.is_to_real(c))
continue;
break; // failed
} }
if (i == num_args) { else if (m_util.is_to_real(c, x)) {
// simplification can be applied int_args.push_back(x);
expr_ref_buffer new_args(m()); }
for (i = 0; i < num_args; i++) { else {
expr * c = to_app(arg)->get_arg(i); real_args.push_back(c);
if (m_util.is_numeral(c, a) && a.is_int()) {
new_args.push_back(m_util.mk_numeral(a, true));
}
else {
VERIFY (m_util.is_to_real(c, x));
new_args.push_back(x);
}
}
SASSERT(num_args == new_args.size());
result = m().mk_app(get_fid(), to_app(arg)->get_decl()->get_decl_kind(), new_args.size(), new_args.c_ptr());
return BR_REWRITE1;
} }
} }
return BR_FAILED; if (real_args.empty()) {
result = m().mk_app(get_fid(), to_app(arg)->get_decl()->get_decl_kind(), int_args.size(), int_args.c_ptr());
return BR_REWRITE1;
}
if (!int_args.empty() && (m_util.is_add(arg) || m_util.is_mul(arg))) {
decl_kind k = to_app(arg)->get_decl()->get_decl_kind();
expr_ref t1(m().mk_app(get_fid(), k, int_args.size(), int_args.c_ptr()), m());
expr_ref t2(m().mk_app(get_fid(), k, real_args.size(), real_args.c_ptr()), m());
int_args.reset();
int_args.push_back(t1);
int_args.push_back(m_util.mk_to_int(t2));
result = m().mk_app(get_fid(), k, int_args.size(), int_args.c_ptr());
return BR_REWRITE3;
}
} }
return BR_FAILED;
} }
br_status arith_rewriter::mk_to_real_core(expr * arg, expr_ref & result) { br_status arith_rewriter::mk_to_real_core(expr * arg, expr_ref & result) {