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btorrewrite.c
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btorrewrite.c
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/* Boolector: Satisfiability Modulo Theories (SMT) solver.
*
* Copyright (C) 2007-2009 Robert Daniel Brummayer.
* Copyright (C) 2007-2017 Armin Biere.
* Copyright (C) 2013-2017 Mathias Preiner.
* Copyright (C) 2014-2018 Aina Niemetz.
*
* This file is part of Boolector.
* See COPYING for more information on using this software.
*/
#include "btorbeta.h"
#include "btorbv.h"
#include "btorcore.h"
#include "btordbg.h"
#include "btorexp.h"
#include "btorlog.h"
#include "utils/btorhashint.h"
#include "utils/btorhashptr.h"
#include "utils/btormem.h"
#include "utils/btornodeiter.h"
#include "utils/btorutil.h"
#include "btorrewrite.h"
#include <assert.h>
// TODO: mul: power of 2 optimizations
/* TODO: lots of word level simplifications:
* a[7:4] == b[7:4] && a[3:0] == b[3:0] <=> a == b
* {a,b} == {c,d} with |a|=|c| <=> a == c && b == d
* ...
*/
/* TODO a + 2 * a <=> 3 * a <=> and see below */
/* TODO strength reduction: a * 2 == a << 1 (really ?) */
/* TODO strength reduction: a * 3 == (a << 1) + a (really ?) */
/* TODO strength reduction: a / 2 == (a >> 1) (yes!) */
/* TODO strength reduction: a / 3 => higher bits zero (check!) */
/* TODO MAX-1 < a <=> a == MAX */
/* TODO (x < ~x) <=> !msb(x) */
/* TODO (~x < x) <=> msb(x) */
/* TODO to support GAUSS bubble up odd terms:
* (2 * a + 3 * y) + 4 * x => 3 * y + (2 * a + 4 * x)
* or alternatively normalize arithmetic terms/polynomials
* or simply always replace by equation.
*/
/* TODO simplify (c * x + 2 * y) + x == 5 at GAUSS application
* by first (c + 1) * x + 2 * y == 5 and then check whether 'c'
* is even.
*/
/* TODO Howto handle 2 * x == 4 && 4 * x + 8 * y == 0 ?
* Maybe: x[30:0] == 2 && 4 * {x[31],2[30:0]} + 8 * y == 0?
* Then: x[30:0] == 2 && 8[31:0] + 8 *y == 0?
* Then: x[30:0] = 2 && 8 * y = -8
* Finally: x[30:0] = 2 && y[29:0] = -1
* etc.
*/
/* recursive rewriting bound */
#define BTOR_REC_RW_BOUND (1 << 12)
/* iterative rewriting bounds */
#define BTOR_WRITE_CHAIN_NODE_RW_BOUND (1 << 5)
#define BTOR_READ_OVER_WRITE_DOWN_PROPAGATION_LIMIT (1 << 11)
#define BTOR_APPLY_PROPAGATION_LIMIT (1 << 13)
/* other rewriting bounds */
#define BTOR_FIND_AND_NODE_CONTRADICTION_LIMIT (1 << 4)
#define BTOR_INC_REC_RW_CALL(btor) \
do \
{ \
(btor)->rec_rw_calls++; \
if ((btor)->rec_rw_calls > (btor)->stats.max_rec_rw_calls) \
(btor)->stats.max_rec_rw_calls = (btor)->rec_rw_calls; \
} while (0)
#define BTOR_DEC_REC_RW_CALL(btor) \
do \
{ \
assert ((btor)->rec_rw_calls > 0); \
(btor)->rec_rw_calls--; \
} while (0)
// TODO: special_const_binary rewriting may return 0, hence the check if
// (result), may be obsolete if special_const_binary will be split
#ifndef NDEBUG
#define ADD_RW_RULE(rw_rule, ...) \
if (applies_##rw_rule (btor, __VA_ARGS__)) \
{ \
assert (!result); \
result = apply_##rw_rule (btor, __VA_ARGS__); \
if (result) \
{ \
if (btor->stats.rw_rules_applied) \
{ \
BtorPtrHashBucket *b = \
btor_hashptr_table_get (btor->stats.rw_rules_applied, #rw_rule); \
if (!b) \
b = btor_hashptr_table_add (btor->stats.rw_rules_applied, #rw_rule); \
b->data.as_int += 1; \
} \
goto DONE; \
} \
}
#else
#define ADD_RW_RULE(rw_rule, ...) \
if (applies_##rw_rule (btor, __VA_ARGS__)) \
{ \
assert (!result); \
result = apply_##rw_rule (btor, __VA_ARGS__); \
if (result) goto DONE; \
}
#endif
//{fprintf (stderr, "apply: %s (%s)\n", #rw_rule, __FUNCTION__);
/* -------------------------------------------------------------------------- */
/* util functions */
static bool
is_const_zero_exp (Btor *btor, BtorNode *exp)
{
assert (btor);
assert (exp);
bool result;
exp = btor_simplify_exp (btor, exp);
if (!btor_node_is_bv_const (exp)) return false;
if (btor_node_is_inverted (exp))
result = btor_bv_is_ones (btor_node_const_get_bits (exp));
else
result = btor_bv_is_zero (btor_node_const_get_bits (exp));
return result;
}
#if 0
static bool
is_const_ones_exp (Btor * btor, BtorNode * exp)
{
assert (btor);
assert (exp);
bool result;
exp = btor_simplify_exp (btor, exp);
if (!btor_node_is_bv_const (exp))
return false;
if (btor_node_is_inverted (exp))
result = btor_is_zero_const (btor_node_const_get_bits (exp));
else
result = btor_is_ones_const (btor_node_const_get_bits (exp));
return result;
}
#endif
static bool
is_const_zero_or_ones_exp (Btor *btor, BtorNode *exp)
{
assert (btor);
assert (exp);
bool result;
BtorBitVector *bits;
exp = btor_simplify_exp (btor, exp);
if (!btor_node_is_bv_const (exp)) return false;
bits = btor_node_const_get_bits (exp);
result = btor_bv_is_zero (bits) || btor_bv_is_ones (bits);
return result;
}
static bool
is_odd_const_exp (BtorNode *exp)
{
BtorBitVector *bits;
if (btor_node_is_inverted (exp)) return false;
if (exp->kind != BTOR_BV_CONST_NODE) return false;
bits = btor_node_const_get_bits (exp);
return btor_bv_get_bit (bits, 0) == 1;
}
static bool
is_xor_exp (Btor *btor, BtorNode *exp)
{
assert (btor);
assert (exp);
BtorNode *e0, *e1, *e0_0, *e0_1, *e1_0, *e1_1;
exp = btor_simplify_exp (btor, exp);
(void) btor;
if (btor_node_real_addr (exp)->kind != BTOR_AND_NODE) return false;
e0 = btor_node_real_addr (exp)->e[0];
if (!(btor_node_is_inverted (e0)
&& btor_node_real_addr (e0)->kind == BTOR_AND_NODE))
return false;
e1 = btor_node_real_addr (exp)->e[1];
if (!(btor_node_is_inverted (e1)
&& btor_node_real_addr (e1)->kind == BTOR_AND_NODE))
return false;
e0_0 = btor_node_real_addr (e0)->e[0];
e0_1 = btor_node_real_addr (e0)->e[1];
e1_0 = btor_node_real_addr (e1)->e[0];
e1_1 = btor_node_real_addr (e1)->e[1];
/* we assume that the children of commutative operators are sorted by id */
/* are children of e0 the same children as of e1 (ignoring sign) ? */
/* if not we terminate with false */
if (btor_node_real_addr (e0_0) != btor_node_real_addr (e1_0)) return false;
if (btor_node_real_addr (e0_1) != btor_node_real_addr (e1_1)) return false;
/* we check for two cases */
/* first case: !(!a && !b) && !(a && b) */
if (!btor_node_is_inverted (exp))
{
if (btor_node_is_inverted (e0_0) == btor_node_is_inverted (e0_1)
&& btor_node_is_inverted (e1_0) == btor_node_is_inverted (e1_1)
&& btor_node_is_inverted (e0_0) != btor_node_is_inverted (e1_0))
return true;
}
/* second case: !((!a && b) && !(a && !b)) */
else
{
if (btor_node_is_inverted (e0_0) != btor_node_is_inverted (e1_0)
&& btor_node_is_inverted (e0_1) != btor_node_is_inverted (e1_1)
&& btor_node_is_inverted (e0_0) != btor_node_is_inverted (e0_1))
return true;
}
return false;
}
static bool
is_xnor_exp (Btor *btor, BtorNode *exp)
{
assert (btor);
assert (exp);
exp = btor_simplify_exp (btor, exp);
return is_xor_exp (btor, btor_node_invert (exp));
}
static bool
slice_simplifiable (BtorNode *exp)
{
exp = btor_node_real_addr (exp);
return btor_node_is_bv_var (exp) || btor_node_is_bv_const (exp)
|| btor_node_is_slice (exp);
}
static bool
is_always_unequal (Btor *btor, BtorNode *e0, BtorNode *e1)
{
BtorNode *real_e0, *real_e1;
BtorNode *e0_const = 0, *e0_node = 0, *e1_const = 0, *e1_node = 0;
e0 = btor_simplify_exp (btor, e0);
e1 = btor_simplify_exp (btor, e1);
assert (btor);
assert (e0);
assert (e1);
/* we need this so that a + 0 is rewritten to a,
* and constants are normalized (all inverted constants are odd) */
assert (btor_opt_get (btor, BTOR_OPT_REWRITE_LEVEL) > 0);
real_e0 = btor_node_real_addr (e0);
real_e1 = btor_node_real_addr (e1);
if (!real_e0 || !real_e1) return 0;
if (btor_node_is_fun (real_e0))
{
assert (btor_node_is_fun (real_e1));
return false;
}
assert (!btor_node_is_fun (real_e1));
if (e0 == btor_node_invert (e1)) return true;
if (btor_node_is_bv_const (real_e0) && btor_node_is_bv_const (real_e1)
&& e0 != e1)
return true;
if (btor_node_is_add (real_e0))
{
if (btor_node_is_bv_const (real_e0->e[0]))
{
e0_const = real_e0->e[0];
e0_node = real_e0->e[1];
}
else if (btor_node_is_bv_const (real_e0->e[1]))
{
e0_const = real_e0->e[1];
e0_node = real_e0->e[0];
}
if (e0_const && !is_const_zero_exp (btor, e0_const)
&& btor_node_cond_invert (e0, e0_node) == e1)
return true;
}
if (btor_node_is_add (real_e1))
{
if (btor_node_is_bv_const (real_e1->e[0]))
{
e1_const = real_e1->e[0];
e1_node = real_e1->e[1];
}
else if (btor_node_is_bv_const (real_e1->e[1]))
{
e1_const = real_e1->e[1];
e1_node = real_e1->e[0];
}
if (e1_const && !is_const_zero_exp (btor, e1_const)
&& btor_node_cond_invert (e1, e1_node) == e1)
return true;
}
if (e0_const && e1_const
&& btor_node_is_inverted (e0) == btor_node_is_inverted (e1))
{
return e0_node == e1_node && e0_const != e1_const;
}
return false;
}
static int32_t
cmp_node_id (const void *p, const void *q)
{
BtorNode *a = *(BtorNode **) p;
BtorNode *b = *(BtorNode **) q;
return btor_node_real_addr (a)->id - btor_node_real_addr (b)->id;
}
static bool
find_and_contradiction_exp (
Btor *btor, BtorNode *exp, BtorNode *e0, BtorNode *e1, uint32_t *calls)
{
assert (btor);
assert (exp);
assert (e0);
assert (e1);
assert (calls);
(void) btor;
if (*calls >= BTOR_FIND_AND_NODE_CONTRADICTION_LIMIT) return false;
if (!btor_node_is_inverted (exp) && exp->kind == BTOR_AND_NODE)
{
if (exp->e[0] == btor_node_invert (e0) || exp->e[0] == btor_node_invert (e1)
|| exp->e[1] == btor_node_invert (e0)
|| exp->e[1] == btor_node_invert (e1))
return true;
*calls += 1;
return find_and_contradiction_exp (btor, exp->e[0], e0, e1, calls)
|| find_and_contradiction_exp (btor, exp->e[1], e0, e1, calls);
}
return false;
}
static bool
is_concat_simplifiable (BtorNode *exp)
{
return btor_node_is_bv_var (exp) || btor_node_is_bv_const (exp);
}
static bool
is_write_exp (BtorNode *exp,
BtorNode **array,
BtorNode **index,
BtorNode **value)
{
assert (exp);
assert (btor_node_is_regular (exp));
BtorNode *param, *body, *eq, *app;
if (!btor_node_is_lambda (exp)
|| btor_node_fun_get_arity (exp->btor, exp) > 1)
return false;
param = exp->e[0];
body = btor_node_binder_get_body (exp);
if (btor_node_is_inverted (body) || !btor_node_is_bv_cond (body))
return false;
/* check condition */
eq = body->e[0];
if (btor_node_is_inverted (eq) || !btor_node_is_bv_eq (eq)
|| !eq->parameterized || (eq->e[0] != param && eq->e[1] != param))
return false;
/* check value */
if (btor_node_real_addr (body->e[1])->parameterized) return false;
/* check apply on unmodified array */
app = body->e[2];
if (btor_node_is_inverted (app) || !btor_node_is_apply (app)
|| btor_node_args_get_arity (app->btor, app->e[1]) > 1
|| app->e[1]->e[0] != param)
return false;
if (array) *array = app->e[0];
if (index) *index = eq->e[1] == param ? eq->e[0] : eq->e[1];
if (value) *value = body->e[1];
return true;
}
static bool
is_true_cond (BtorNode *cond)
{
assert (cond);
assert (btor_node_get_width (btor_node_real_addr (cond)->btor, cond) == 1);
if (btor_node_is_inverted (cond)
&& !btor_bv_get_bit (btor_node_const_get_bits (cond), 0))
return true;
else if (!btor_node_is_inverted (cond)
&& btor_bv_get_bit (btor_node_const_get_bits (cond), 0))
return true;
return false;
}
#if 0
static bool
is_bit_mask (BtorNode * exp, uint32_t * upper, uint32_t * lower)
{
uint32_t i, len, inv, bit;
int32_t first, last;
BtorBitVector *bits;
BtorNode *real_exp;
real_exp = btor_node_real_addr (exp);
*upper = 0; *lower = 0;
first = -1; last = -1;
if (!btor_node_is_bv_const (real_exp))
return false;
bits = btor_node_const_get_bits (real_exp);
inv = btor_node_is_inverted (exp);
len = btor_node_get_width (real_exp->btor, real_exp);
for (i = 0; i < len; i++)
{
bit = btor_bv_get_bit (bits, i);
if (inv) bit ^= 1;
if (bit && first == -1)
first = i;
else if (!bit && first > -1 && last == -1)
last = i - 1;
if (bit && last > -1)
return false;
}
if (last == -1)
last = len - 1;
*upper = last;
*lower = first;
return true;
}
#endif
static bool
is_urem_exp (Btor *btor,
BtorNode *e0,
BtorNode *e1,
BtorNode **res_e0,
BtorNode **res_e1)
{
BtorNode *mul, *udiv, *x, *y;
if (btor_node_is_neg (btor, e0, &mul))
x = e1;
else if (btor_node_is_neg (btor, e1, &mul))
x = e0;
else
return false;
if (btor_node_is_inverted (mul) || !btor_node_is_mul (mul)) return false;
if (!btor_node_is_inverted (mul->e[0]) && btor_node_is_udiv (mul->e[0]))
{
udiv = mul->e[0];
y = mul->e[0];
}
else if (!btor_node_is_inverted (mul->e[1]) && btor_node_is_udiv (mul->e[1]))
{
udiv = mul->e[1];
y = mul->e[0];
}
else
return false;
if (udiv->e[0] == x && udiv->e[1] == y)
{
if (res_e0) *res_e0 = x;
if (res_e1) *res_e1 = y;
return true;
}
return false;
}
/* -------------------------------------------------------------------------- */
static BtorNode *rewrite_slice_exp (Btor *, BtorNode *, uint32_t, uint32_t);
static BtorNode *rewrite_eq_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_ult_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_and_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_add_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_mul_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_udiv_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_urem_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_concat_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_sll_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_srl_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_apply_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_lambda_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_forall_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_exists_exp (Btor *, BtorNode *, BtorNode *);
static BtorNode *rewrite_cond_exp (Btor *, BtorNode *, BtorNode *, BtorNode *);
/* -------------------------------------------------------------------------- */
/* const term rewriting */
/* match: binary op with two constants
* result: constant
*/
static inline bool
applies_const_binary_exp (Btor *btor,
BtorNodeKind kind,
BtorNode *e0,
BtorNode *e1)
{
(void) btor;
(void) kind;
return btor_node_is_bv_const (e0) && btor_node_is_bv_const (e1);
}
static inline BtorNode *
apply_const_binary_exp (Btor *btor,
BtorNodeKind kind,
BtorNode *e0,
BtorNode *e1)
{
assert (applies_const_binary_exp (btor, kind, e0, e1));
bool invert_b0, invert_b1;
BtorBitVector *b0, *b1, *bresult;
BtorMemMgr *mm;
BtorNode *result, *real_e0, *real_e1;
mm = btor->mm;
real_e0 = btor_node_real_addr (e0);
real_e1 = btor_node_real_addr (e1);
invert_b0 = btor_node_is_inverted (e0);
invert_b1 = btor_node_is_inverted (e1);
b0 = btor_node_const_get_bits (real_e0);
b1 = btor_node_const_get_bits (real_e1);
if (invert_b0) b0 = btor_bv_not (mm, b0);
if (invert_b1) b1 = btor_bv_not (mm, b1);
switch (kind)
{
case BTOR_AND_NODE: bresult = btor_bv_and (mm, b0, b1); break;
case BTOR_BV_EQ_NODE: bresult = btor_bv_eq (mm, b0, b1); break;
case BTOR_ADD_NODE: bresult = btor_bv_add (mm, b0, b1); break;
case BTOR_MUL_NODE: bresult = btor_bv_mul (mm, b0, b1); break;
case BTOR_ULT_NODE: bresult = btor_bv_ult (mm, b0, b1); break;
case BTOR_UDIV_NODE: bresult = btor_bv_udiv (mm, b0, b1); break;
case BTOR_UREM_NODE: bresult = btor_bv_urem (mm, b0, b1); break;
case BTOR_SLL_NODE: bresult = btor_bv_sll (mm, b0, b1); break;
case BTOR_SRL_NODE: bresult = btor_bv_srl (mm, b0, b1); break;
default:
assert (kind == BTOR_CONCAT_NODE);
bresult = btor_bv_concat (mm, b0, b1);
break;
}
if (invert_b0) btor_bv_free (mm, b0);
if (invert_b1) btor_bv_free (mm, b1);
result = btor_exp_const (btor, bresult);
btor_bv_free (mm, bresult);
return result;
}
/* match: binary op with one constant
* result: constant
*/
static inline bool
applies_special_const_lhs_binary_exp (Btor *btor,
BtorNodeKind kind,
BtorNode *e0,
BtorNode *e1)
{
(void) btor;
(void) kind;
return btor_node_is_bv_const (e0) && !btor_node_is_bv_const (e1);
}
static inline BtorNode *
apply_special_const_lhs_binary_exp (Btor *btor,
BtorNodeKind kind,
BtorNode *e0,
BtorNode *e1)
{
assert (applies_special_const_lhs_binary_exp (btor, kind, e0, e1));
char tmpstr[2] = {'\0', '\0'}, *bvstr;
uint32_t pos, len, width_e0;
bool invert_b0;
BtorBitVector *b0, *bv;
BtorMemMgr *mm;
BtorSpecialConstBitVector sc;
BtorNode *result = 0, *real_e0, *real_e1, *left, *right, *tmp1, *tmp2, *tmp3;
BtorNode *tmp4, *eq;
BtorNodePtrStack stack;
BtorSortId sort;
mm = btor->mm;
real_e0 = btor_node_real_addr (e0);
real_e1 = btor_node_real_addr (e1);
invert_b0 = btor_node_is_inverted (e0);
b0 = btor_node_const_get_bits (real_e0);
width_e0 = btor_node_get_width (btor, real_e0);
if (invert_b0) b0 = btor_bv_not (mm, b0);
sc = btor_bv_is_special_const (b0);
if (invert_b0) btor_bv_free (mm, b0);
switch (sc)
{
case BTOR_SPECIAL_CONST_BV_ZERO:
switch (kind)
{
case BTOR_BV_EQ_NODE:
if (width_e0 == 1)
result = btor_exp_not (btor, e1);
else if (is_xor_exp (btor, e1)) /* 0 == (a ^ b) --> a = b */
{
if (btor->rec_rw_calls < BTOR_REC_RW_BOUND)
{
BTOR_INC_REC_RW_CALL (btor);
result = rewrite_eq_exp (
btor,
btor_node_real_addr (
btor_node_real_addr (btor_node_real_addr (e1)->e[0])
->e[0]),
btor_node_real_addr (
btor_node_real_addr (btor_node_real_addr (e1)->e[0])
->e[1]));
BTOR_DEC_REC_RW_CALL (btor);
}
}
else if (btor_node_is_inverted (e1) && real_e1->kind == BTOR_AND_NODE)
{ /* 0 == a | b --> a == 0 && b == 0 */
if (btor->rec_rw_calls < BTOR_REC_RW_BOUND)
{
BTOR_INC_REC_RW_CALL (btor);
left =
rewrite_eq_exp (btor, btor_node_invert (real_e1->e[0]), e0);
right =
rewrite_eq_exp (btor, btor_node_invert (real_e1->e[1]), e0);
result = rewrite_and_exp (btor, left, right);
BTOR_DEC_REC_RW_CALL (btor);
btor_node_release (btor, left);
btor_node_release (btor, right);
}
}
break;
case BTOR_ULT_NODE: /* 0 < a --> a != 0 */
result = btor_node_invert (rewrite_eq_exp (btor, e0, e1));
break;
case BTOR_ADD_NODE: result = btor_node_copy (btor, e1); break;
case BTOR_MUL_NODE:
case BTOR_SLL_NODE:
case BTOR_SRL_NODE:
case BTOR_UREM_NODE:
case BTOR_AND_NODE:
result = btor_exp_zero (btor, btor_node_get_sort_id (real_e0));
break;
case BTOR_UDIV_NODE:
tmp2 = btor_exp_zero (btor, btor_node_get_sort_id (real_e0));
tmp4 = btor_exp_ones (btor, btor_node_get_sort_id (real_e0));
eq = rewrite_eq_exp (btor, e1, tmp2);
result = rewrite_cond_exp (btor, eq, tmp4, tmp2);
btor_node_release (btor, tmp2);
btor_node_release (btor, eq);
btor_node_release (btor, tmp4);
break;
default: break;
}
break;
case BTOR_SPECIAL_CONST_BV_ONE_ONES:
assert (width_e0 == 1);
if (kind == BTOR_AND_NODE || kind == BTOR_BV_EQ_NODE
|| kind == BTOR_MUL_NODE)
result = btor_node_copy (btor, e1);
else if (kind == BTOR_ULT_NODE)
result = btor_exp_false (btor);
break;
case BTOR_SPECIAL_CONST_BV_ONE:
if (kind == BTOR_MUL_NODE) result = btor_node_copy (btor, e1);
break;
case BTOR_SPECIAL_CONST_BV_ONES:
if (kind == BTOR_BV_EQ_NODE)
{
if (is_xnor_exp (btor, e1)) /* 1+ == (a XNOR b) --> a = b */
{
if (btor->rec_rw_calls < BTOR_REC_RW_BOUND)
{
BTOR_INC_REC_RW_CALL (btor);
result = rewrite_eq_exp (
btor,
btor_node_real_addr (
btor_node_real_addr (btor_node_real_addr (e1)->e[0])->e[0]),
btor_node_real_addr (
btor_node_real_addr (btor_node_real_addr (e1)->e[0])
->e[1]));
BTOR_DEC_REC_RW_CALL (btor);
}
}
else if (!btor_node_is_inverted (e1) && e1->kind == BTOR_AND_NODE)
{ /* 1+ == a & b --> a == 1+ && b == 1+ */
if (btor->rec_rw_calls < BTOR_REC_RW_BOUND)
{
BTOR_INC_REC_RW_CALL (btor);
left = rewrite_eq_exp (btor, e1->e[0], e0);
right = rewrite_eq_exp (btor, e1->e[1], e0);
result = rewrite_and_exp (btor, left, right);
BTOR_DEC_REC_RW_CALL (btor);
btor_node_release (btor, left);
btor_node_release (btor, right);
}
}
}
else if (kind == BTOR_AND_NODE)
result = btor_node_copy (btor, e1);
else if (kind == BTOR_ULT_NODE) /* UNSIGNED_MAX < x */
result = btor_exp_false (btor);
else if (kind == BTOR_MUL_NODE)
result = btor_exp_neg (btor, e1);
break;
default:
assert (sc == BTOR_SPECIAL_CONST_BV_NONE);
if (kind == BTOR_BV_EQ_NODE && real_e1->kind == BTOR_AND_NODE
&& btor->rec_rw_calls < BTOR_REC_RW_BOUND)
{
BTOR_INC_REC_RW_CALL (btor);
BTOR_INIT_STACK (btor->mm, stack);
if (btor_node_is_inverted (e0))
bv = btor_bv_not (btor->mm, btor_node_const_get_bits (real_e0));
else
bv = btor_bv_copy (btor->mm, btor_node_const_get_bits (real_e0));
pos = 0;
/* const == a | b */
if (btor_node_is_inverted (e1))
{
while (pos < width_e0)
{
bvstr = btor_bv_to_char (btor->mm, bv);
tmpstr[0] = bvstr[pos];
len = (uint32_t) strspn (bvstr + pos, tmpstr);
btor_mem_freestr (btor->mm, bvstr);
tmp1 = rewrite_slice_exp (btor,
btor_node_invert (real_e1->e[0]),
width_e0 - 1 - pos,
width_e0 - pos - len);
tmp2 = rewrite_slice_exp (btor,
btor_node_invert (real_e1->e[1]),
width_e0 - 1 - pos,
width_e0 - pos - len);
sort = btor_sort_bitvec (btor, len);
if (tmpstr[0] == '0')
{
tmp3 = btor_exp_zero (btor, sort);
BTOR_PUSH_STACK (stack, rewrite_eq_exp (btor, tmp1, tmp3));
BTOR_PUSH_STACK (stack, rewrite_eq_exp (btor, tmp2, tmp3));
btor_node_release (btor, tmp3);
}
else
{
assert (tmpstr[0] == '1');
tmp3 = btor_exp_or (btor, tmp1, tmp2);
tmp4 = btor_exp_ones (btor, sort);
BTOR_PUSH_STACK (stack, rewrite_eq_exp (btor, tmp3, tmp4));
btor_node_release (btor, tmp3);
btor_node_release (btor, tmp4);
}
btor_sort_release (btor, sort);
btor_node_release (btor, tmp1);
btor_node_release (btor, tmp2);
pos += len;
}
}
else
{
assert (!btor_node_is_inverted (e1));
/* const == a & b */
while (pos < width_e0)
{
bvstr = btor_bv_to_char (btor->mm, bv);
tmpstr[0] = bvstr[pos];
len = (uint32_t) strspn (bvstr + pos, tmpstr);
btor_mem_freestr (btor->mm, bvstr);
tmp1 = rewrite_slice_exp (
btor, e1->e[0], width_e0 - 1 - pos, width_e0 - pos - len);
tmp2 = rewrite_slice_exp (
btor, e1->e[1], width_e0 - 1 - pos, width_e0 - pos - len);
sort = btor_sort_bitvec (btor, len);
if (tmpstr[0] == '1')
{
tmp3 = btor_exp_ones (btor, sort);
BTOR_PUSH_STACK (stack, rewrite_eq_exp (btor, tmp1, tmp3));
BTOR_PUSH_STACK (stack, rewrite_eq_exp (btor, tmp2, tmp3));
btor_node_release (btor, tmp3);
}
else
{
assert (tmpstr[0] == '0');
tmp3 = rewrite_and_exp (btor, tmp1, tmp2);
tmp4 = btor_exp_zero (btor, sort);
BTOR_PUSH_STACK (stack, rewrite_eq_exp (btor, tmp3, tmp4));
btor_node_release (btor, tmp3);
btor_node_release (btor, tmp4);
}
btor_sort_release (btor, sort);
btor_node_release (btor, tmp1);
btor_node_release (btor, tmp2);
pos += len;
}
}
result = btor_exp_true (btor);
assert (!BTOR_EMPTY_STACK (stack));
do
{
tmp1 = BTOR_POP_STACK (stack);
tmp2 = rewrite_and_exp (btor, result, tmp1);
btor_node_release (btor, result);
result = tmp2;
btor_node_release (btor, tmp1);
} while (!BTOR_EMPTY_STACK (stack));
btor_bv_free (btor->mm, bv);
BTOR_RELEASE_STACK (stack);
BTOR_DEC_REC_RW_CALL (btor);
}
break;
}
return result;
}
/* match: binary op with one constant
* result: constant
*/
static inline bool
applies_special_const_rhs_binary_exp (Btor *btor,
BtorNodeKind kind,
BtorNode *e0,
BtorNode *e1)
{
(void) btor;
(void) kind;
return !btor_node_is_bv_const (e0) && btor_node_is_bv_const (e1);
}
static inline BtorNode *
apply_special_const_rhs_binary_exp (Btor *btor,
BtorNodeKind kind,
BtorNode *e0,
BtorNode *e1)
{
assert (applies_special_const_rhs_binary_exp (btor, kind, e0, e1));
char tmpstr[2] = {'\0', '\0'}, *bvstr;
uint32_t pos, len, width_e0, width_e1;
bool invert_b1;
BtorBitVector *b1, *bv;
BtorMemMgr *mm;
BtorSpecialConstBitVector sc;
BtorNode *result = 0, *real_e0, *real_e1, *left, *right, *tmp1, *tmp2, *tmp3;
BtorNode *tmp4;
BtorNodePtrStack stack;
BtorSortId sort;
mm = btor->mm;
real_e0 = btor_node_real_addr (e0);
real_e1 = btor_node_real_addr (e1);
invert_b1 = btor_node_is_inverted (e1);
b1 = btor_node_const_get_bits (real_e1);
width_e0 = btor_node_get_width (btor, real_e0);
width_e1 = btor_node_get_width (btor, real_e1);
if (invert_b1) b1 = btor_bv_not (mm, b1);
sc = btor_bv_is_special_const (b1);
if (invert_b1) btor_bv_free (mm, b1);
switch (sc)
{
case BTOR_SPECIAL_CONST_BV_ZERO:
switch (kind)
{
case BTOR_BV_EQ_NODE:
if (width_e0 == 1)
result = btor_exp_not (btor, e0);
else if (is_xor_exp (btor, e0)) /* (a ^ b) == 0 --> a = b */
{
if (btor->rec_rw_calls < BTOR_REC_RW_BOUND)
{
BTOR_INC_REC_RW_CALL (btor);
result = rewrite_eq_exp (
btor,
btor_node_real_addr (
btor_node_real_addr (btor_node_real_addr (e0)->e[0])
->e[0]),
btor_node_real_addr (
btor_node_real_addr (btor_node_real_addr (e0)->e[0])
->e[1]));
BTOR_DEC_REC_RW_CALL (btor);
}
}
else if (btor_node_is_inverted (e0) && real_e0->kind == BTOR_AND_NODE)
{ /* a | b == 0 --> a == 0 && b == 0 */
if (btor->rec_rw_calls < BTOR_REC_RW_BOUND)
{
BTOR_INC_REC_RW_CALL (btor);
left =
rewrite_eq_exp (btor, btor_node_invert (real_e0->e[0]), e1);
right =
rewrite_eq_exp (btor, btor_node_invert (real_e0->e[1]), e1);
result = rewrite_and_exp (btor, left, right);
BTOR_DEC_REC_RW_CALL (btor);
btor_node_release (btor, left);
btor_node_release (btor, right);
}
}
break;
case BTOR_SLL_NODE:
case BTOR_SRL_NODE:
case BTOR_UREM_NODE:
case BTOR_ADD_NODE: result = btor_node_copy (btor, e0); break;
case BTOR_MUL_NODE:
case BTOR_AND_NODE:
result = btor_exp_zero (btor, btor_node_get_sort_id (real_e0));
break;
case BTOR_ULT_NODE: /* x < 0 */ result = btor_exp_false (btor); break;
case BTOR_UDIV_NODE:
result = btor_exp_ones (btor, btor_node_get_sort_id (real_e0));
break;
default: break;
}
break;
case BTOR_SPECIAL_CONST_BV_ONE_ONES:
assert (width_e1 == 1);
if (kind == BTOR_AND_NODE || kind == BTOR_BV_EQ_NODE
|| kind == BTOR_MUL_NODE || kind == BTOR_UDIV_NODE)
result = btor_node_copy (btor, e0);
break;
case BTOR_SPECIAL_CONST_BV_ONE:
if (kind == BTOR_MUL_NODE || kind == BTOR_UDIV_NODE)
result = btor_node_copy (btor, e0);
else if (kind == BTOR_UREM_NODE)
result = btor_exp_zero (btor, btor_node_get_sort_id (real_e0));
else if (kind == BTOR_ULT_NODE)
{
tmp1 = btor_exp_zero (btor, btor_node_get_sort_id (real_e0));
result = rewrite_eq_exp (btor, e0, tmp1);
btor_node_release (btor, tmp1);
}
break;
case BTOR_SPECIAL_CONST_BV_ONES: