bool restrict_bv_size(typet &type, const size_t width_in_bits)
{
const irep_idt &type_id=type.id();
if (ID_code == type_id)
return restrict_bv_size(to_code_type(type), width_in_bits);
if (ID_struct == type_id || ID_union == type_id)
return restrict_bv_size(to_struct_union_type(type), width_in_bits);
if (static_cast<const typet &>(type).subtype().is_not_nil())
restrict_bv_size(type.subtype(), width_in_bits);
if (!is_bv_type(type)) return false;
bitvector_typet &bvtype=to_bitvector_type(type);
if (width_in_bits >= bvtype.get_width()) return false;
to_bitvector_type(type).set_width(width_in_bits);
return true;
}
/*
* Print what's mapped to t in the context's internalization table.
* - if t is mapped to a Boolean, the corresponding DIMACS literal is printed
* - if t is mapped to a bitvector then the corresponding literal array is printed
* - otherwise we print "non boolean"
*/
void dimacs_print_internalized_term(FILE *f, context_t *ctx, term_t t) {
intern_tbl_t *intern;
type_table_t *types;
term_t r;
type_t tau;
int32_t code;
uint32_t polarity;
intern = &ctx->intern;
types = ctx->types;
r = intern_tbl_get_root(intern, t);
if (t != r) {
// substitution: t --> r (can't deal with this)
fputs("eliminated", f);
} else if (intern_tbl_root_is_mapped(intern, r)) {
// t = r is mapped to something
polarity = polarity_of(r);
r = unsigned_term(r);
tau = intern_tbl_type_of_root(intern, r);
if (is_boolean_type(tau)) {
// Boolean term
code = intern_tbl_map_of_root(intern, r);
assert(code_is_valid(code));
dimacs_print_bool_code(f, code, polarity);
} else if (is_bv_type(types, tau)) {
// Bitvector term
code = intern_tbl_map_of_root(intern, r);
assert(code_is_valid(code));
assert(polarity == 0);
dimacs_print_bv_code(f, ctx, code);
} else {
// Can't be converted to DIMACS
fputs("non boolean", f);
}
} else {
// r not mapped to anything
fputs("not internalized", f);
}
}
smt_astt
smt_convt::convert_byte_update(const expr2tc &expr)
{
const byte_update2t &data = to_byte_update2t(expr);
assert(is_scalar_type(data.source_value) && "Byte update only works on "
"scalar variables now");
if (!is_constant_int2t(data.source_offset)) {
expr2tc source = data.source_value;
unsigned int src_width = source->type->get_width();
if (!is_bv_type(source))
source = typecast2tc(get_uint_type(src_width), source);
expr2tc offs = data.source_offset;
// Endian-ness: if we're in non-"native" endian-ness mode, then flip the
// offset distance. The rest of these calculations will still apply.
if (data.big_endian) {
auto data_size = type_byte_size(*source->type);
constant_int2tc data_size_expr(source->type, data_size - 1);
sub2tc sub(source->type, data_size_expr, offs);
offs = sub;
}
if (offs->type->get_width() != src_width)
offs = typecast2tc(get_uint_type(src_width), offs);
expr2tc update = data.update_value;
if (update->type->get_width() != src_width)
update = typecast2tc(get_uint_type(src_width), update);
// The approach: mask, shift and or. XXX, byte order?
// Massively inefficient.
expr2tc eight = constant_int2tc(get_uint_type(src_width), BigInt(8));
expr2tc effs = constant_int2tc(eight->type, BigInt(255));
offs = mul2tc(eight->type, offs, eight);
expr2tc shl = shl2tc(offs->type, effs, offs);
expr2tc noteffs = bitnot2tc(effs->type, shl);
source = bitand2tc(source->type, source, noteffs);
expr2tc shl2 = shl2tc(offs->type, update, offs);
return convert_ast(bitor2tc(offs->type, shl2, source));
}
// We are merging two values: an 8 bit update value, and a larger source
// value that we will have to merge it into. Start off by collecting
// information about the source values and their widths.
assert(is_number_type(data.source_value->type) && "Byte update of unsupported data type");
smt_astt value, src_value;
unsigned int width_op0, width_op2, src_offset;
value = convert_ast(data.update_value);
src_value = convert_ast(data.source_value);
width_op2 = data.update_value->type->get_width();
width_op0 = data.source_value->type->get_width();
src_offset = to_constant_int2t(data.source_offset).constant_value.to_ulong();
// Flip location if we're in big-endian mode
if (data.big_endian) {
unsigned int data_size =
type_byte_size(*data.source_value->type).to_ulong() - 1;
src_offset = data_size - src_offset;
}
if (int_encoding) {
std::cerr << "Can't byte update in integer mode; rerun in bitvector mode"
<< std::endl;
abort();
}
// Assertion some of our assumptions, which broadly mean that we'll only work
// on bytes that are going into non-byte words
assert(width_op2 == 8 && "Can't byte update non-byte operations");
assert(width_op2 != width_op0 && "Can't byte update bytes, sorry");
smt_astt top, middle, bottom;
// Build in three parts: the most significant bits, any in the middle, and
// the bottom, of the reconstructed / merged output. There might not be a
// middle if the update byte is at the top or the bottom.
unsigned int top_of_update = (8 * src_offset) + 8;
unsigned int bottom_of_update = (8 * src_offset);
if (top_of_update == width_op0) {
top = value;
} else {
smt_sortt s = mk_sort(SMT_SORT_BV, width_op0 - top_of_update, false);
top = mk_extract(src_value, width_op0 - 1, top_of_update, s);
}
if (top == value) {
middle = NULL;
} else {
middle = value;
}
if (src_offset == 0) {
middle = NULL;
bottom = value;
} else {
smt_sortt s = mk_sort(SMT_SORT_BV, bottom_of_update, false);
bottom = mk_extract(src_value, bottom_of_update - 1, 0, s);
}
// Concatenate the top and bottom, and possible middle, together.
smt_astt concat;
if (middle != NULL) {
smt_sortt s = mk_sort(SMT_SORT_BV, width_op0 - bottom_of_update, false);
concat = mk_func_app(s, SMT_FUNC_CONCAT, top, middle);
} else {
concat = top;
}
return mk_func_app(src_value->sort, SMT_FUNC_CONCAT, concat, bottom);
}
smt_astt
smt_convt::convert_byte_extract(const expr2tc &expr)
{
const byte_extract2t &data = to_byte_extract2t(expr);
assert(is_scalar_type(data.source_value) && "Byte extract now only works on "
"scalar variables");
if (!is_constant_int2t(data.source_offset)) {
expr2tc source = data.source_value;
unsigned int src_width = source->type->get_width();
if (!is_bv_type(source)) {
source = typecast2tc(get_uint_type(src_width), source);
}
// The approach: the argument is now a bitvector. Just shift it the
// appropriate amount, according to the source offset, and select out the
// bottom byte.
expr2tc offs = data.source_offset;
// Endian-ness: if we're in non-"native" endian-ness mode, then flip the
// offset distance. The rest of these calculations will still apply.
if (data.big_endian) {
auto data_size = type_byte_size(*source->type);
constant_int2tc data_size_expr(source->type, data_size - 1);
sub2tc sub(source->type, data_size_expr, offs);
offs = sub;
}
if (offs->type->get_width() != src_width)
// Z3 requires these two arguments to be the same width
offs = typecast2tc(source->type, data.source_offset);
lshr2tc shr(source->type, source, offs);
smt_astt ext = convert_ast(shr);
smt_astt res = mk_extract(ext, 7, 0, convert_sort(get_uint8_type()));
return res;
}
const constant_int2t &intref = to_constant_int2t(data.source_offset);
unsigned width;
width = data.source_value->type->get_width();
uint64_t upper, lower;
if (!data.big_endian) {
upper = ((intref.constant_value.to_long() + 1) * 8) - 1; //((i+1)*w)-1;
lower = intref.constant_value.to_long() * 8; //i*w;
} else {
uint64_t max = width - 1;
upper = max - (intref.constant_value.to_long() * 8); //max-(i*w);
lower = max - ((intref.constant_value.to_long() + 1) * 8 - 1); //max-((i+1)*w-1);
}
smt_astt source = convert_ast(data.source_value);;
if (int_encoding) {
std::cerr << "Refusing to byte extract in integer mode; re-run in "
"bitvector mode" << std::endl;
abort();
} else {
if (is_bv_type(data.source_value)) {
;
} else if (is_fixedbv_type(data.source_value)) {
;
} else if (is_bool_type(data.source_value)) {
// We cdan extract a byte from a bool -- zero or one.
typecast2tc cast(get_uint8_type(), data.source_value);
source = convert_ast(cast);
} else {
std::cerr << "Unrecognized type in operand to byte extract." << std::endl;
data.dump();
abort();
}
unsigned int sort_sz = data.source_value->type->get_width();
if (sort_sz <= upper) {
smt_sortt s = mk_sort(SMT_SORT_BV, 8, false);
return mk_smt_symbol("out_of_bounds_byte_extract", s);
} else {
return mk_extract(source, upper, lower, convert_sort(expr->type));
}
}
}
