/*
* Insert a looping path (usually an accelerator) into a goto-program,
* beginning at loop_header and jumping back to loop_header via back_jump.
* Stores the locations at which the looping path was added in inserted_path.
*
* THIS DESTROYS looping_path!!
*/
void acceleratet::insert_looping_path(
goto_programt::targett &loop_header,
goto_programt::targett &back_jump,
goto_programt &looping_path,
patht &inserted_path)
{
goto_programt::targett loop_body=loop_header;
++loop_body;
goto_programt::targett jump=program.insert_before(loop_body);
jump->make_goto();
jump->guard=side_effect_expr_nondett(bool_typet());
jump->targets.push_back(loop_body);
program.destructive_insert(loop_body, looping_path);
jump=program.insert_before(loop_body);
jump->make_goto();
jump->guard=true_exprt();
jump->targets.push_back(back_jump);
for(goto_programt::targett t=loop_header;
t!=loop_body;
++t)
{
inserted_path.push_back(path_nodet(t));
}
inserted_path.push_back(path_nodet(back_jump));
}
void all_paths_enumeratort::extend_path(patht &path,
goto_programt::targett t,
int succ) {
goto_programt::targett next;
goto_programt::targetst succs;
exprt guard = true_exprt();
goto_program.get_successors(t, succs);
for (goto_programt::targetst::iterator it = succs.begin();
it != succs.end();
++it) {
if (succ == 0) {
next = *it;
break;
}
succ--;
}
if (t->is_goto()) {
guard = not_exprt(t->guard);
for (goto_programt::targetst::iterator it = t->targets.begin();
it != t->targets.end();
++it) {
if (next == *it) {
guard = t->guard;
break;
}
}
}
path.push_back(path_nodet(next, guard));
}
bool all_paths_enumeratort::next(patht &path)
{
if(last_path.empty())
{
// This is the first time we've been called -- build an initial
// path.
last_path.push_back(path_nodet(loop_header));
// This shouldn't be able to fail.
complete_path(last_path, 0);
if(is_looping(last_path))
{
// If this was a loop path, we're good. If it wasn't,
// we'll keep enumerating paths until we hit a looping one.
// This case is exactly the same as if someone just called
// next() on us.
path.clear();
path.insert(path.begin(), last_path.begin(), last_path.end());
return true;
}
}
do
{
#ifdef DEBUG
std::cout << "Enumerating next path...\n";
#endif
int decision=backtrack(last_path);
complete_path(last_path, decision);
if(is_looping(last_path))
{
path.clear();
path.insert(path.begin(), last_path.begin(), last_path.end());
return true;
}
}
while(!last_path.empty());
// We've enumerated all the paths.
return false;
}
void disjunctive_polynomial_accelerationt::build_path(
scratch_programt &scratch_program, patht &path) {
goto_programt::targett t = loop_header;
do {
goto_programt::targett next;
goto_programt::targetst succs;
goto_program.get_successors(t, succs);
// We should have a looping path, so we should never hit a location
// with no successors.
assert(succs.size() > 0);
if (succs.size() == 1) {
// Only one successor -- accumulate it and move on.
path.push_back(path_nodet(t));
t = succs.front();
continue;
}
// We have multiple successors. Examine the distinguisher variables
// to see which branch was taken.
bool found_branch = false;
for (goto_programt::targetst::iterator it = succs.begin();
it != succs.end();
++it) {
exprt &distinguisher = distinguishing_points[*it];
bool taken = scratch_program.eval(distinguisher).is_true();
if (taken) {
if (!found_branch ||
((*it)->location_number < next->location_number)) {
next = *it;
}
found_branch = true;
}
}
assert(found_branch);
exprt cond = nil_exprt();
if (t->is_goto()) {
// If this was a conditional branch (it probably was), figure out
// if we hit the "taken" or "not taken" branch & accumulate the
// appropriate guard.
cond = not_exprt(t->guard);
for (goto_programt::targetst::iterator it = t->targets.begin();
it != t->targets.end();
++it) {
if (next == *it) {
cond = t->guard;
break;
}
}
}
path.push_back(path_nodet(t, cond));
t = next;
} while (t != loop_header && (loop.find(t) != loop.end()));
}
