#include "snapshot-interface.h"
#include "common.h"
#include "clockvector.h"
+#include "cyclegraph.h"
+#include "promise.h"
#define INITIAL_THREAD_ID 0
/* First thread created will have id INITIAL_THREAD_ID */
next_thread_id(INITIAL_THREAD_ID),
used_sequence_numbers(0),
-
num_executions(0),
current_action(NULL),
diverge(NULL),
nextThread(THREAD_ID_T_NONE),
action_trace(new action_list_t()),
- thread_map(new std::map<int, Thread *>),
- obj_thrd_map(new std::map<void *, std::vector<action_list_t> >()),
+ thread_map(new HashTable<int, Thread *, int>()),
+ obj_map(new HashTable<const void *, action_list_t, uintptr_t, 4>()),
+ obj_thrd_map(new HashTable<void *, std::vector<action_list_t>, uintptr_t, 4 >()),
+ promises(new std::vector<Promise *>()),
thrd_last_action(new std::vector<ModelAction *>(1)),
node_stack(new NodeStack()),
- next_backtrack(NULL)
+ next_backtrack(NULL),
+ cyclegraph(new CycleGraph()),
+ failed_promise(false)
{
}
/** @brief Destructor */
ModelChecker::~ModelChecker()
{
- std::map<int, Thread *>::iterator it;
+ /* std::map<int, Thread *>::iterator it;
for (it = thread_map->begin(); it != thread_map->end(); it++)
- delete (*it).second;
+ delete (*it).second;*/
delete thread_map;
delete obj_thrd_map;
+ delete obj_map;
delete action_trace;
delete thrd_last_action;
delete node_stack;
delete scheduler;
+ delete cyclegraph;
}
/**
used_sequence_numbers = 0;
nextThread = 0;
next_backtrack = NULL;
+ failed_promise = false;
snapshotObject->backTrackBeforeStep(0);
}
Thread *t;
if (nextThread == THREAD_ID_T_NONE)
return NULL;
- t = (*thread_map)[id_to_int(nextThread)];
+ t = thread_map->get(id_to_int(nextThread));
ASSERT(t != NULL);
*/
thread_id_t ModelChecker::get_next_replay_thread()
{
- ModelAction *next;
thread_id_t tid;
/* Have we completed exploring the preselected path? */
return THREAD_ID_T_NONE;
/* Else, we are trying to replay an execution */
- next = node_stack->get_next()->get_action();
+ ModelAction * next = node_stack->get_next()->get_action();
if (next == diverge) {
- Node *node = next->get_node()->get_parent();
-
+ Node *nextnode = next->get_node();
/* Reached divergence point */
+ if (nextnode->increment_promises()) {
+ /* The next node will try to satisfy a different set of promises. */
+ tid = next->get_tid();
+ node_stack->pop_restofstack(2);
+ } else if (nextnode->increment_read_from()) {
+ /* The next node will read from a different value. */
+ tid = next->get_tid();
+ node_stack->pop_restofstack(2);
+ } else if (nextnode->increment_future_values()) {
+ /* The next node will try to read from a different future value. */
+ tid = next->get_tid();
+ node_stack->pop_restofstack(2);
+ } else {
+ /* Make a different thread execute for next step */
+ Node *node = nextnode->get_parent();
+ tid = node->get_next_backtrack();
+ node_stack->pop_restofstack(1);
+ }
DEBUG("*** Divergence point ***\n");
- tid = node->get_next_backtrack();
diverge = NULL;
} else {
tid = next->get_tid();
DBG();
num_executions++;
- print_summary();
+
+ if (isfeasible() || DBG_ENABLED())
+ print_summary();
+
if ((diverge = model->get_next_backtrack()) == NULL)
return false;
action_type type = act->get_type();
switch (type) {
- case THREAD_CREATE:
- case THREAD_YIELD:
- case THREAD_JOIN:
- return NULL;
case ATOMIC_READ:
case ATOMIC_WRITE:
- default:
+ case ATOMIC_RMW:
break;
+ default:
+ return NULL;
}
/* linear search: from most recent to oldest */
+ action_list_t *list = obj_map->ensureptr(act->get_location());
action_list_t::reverse_iterator rit;
- for (rit = action_trace->rbegin(); rit != action_trace->rend(); rit++) {
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *prev = *rit;
if (act->is_synchronizing(prev))
return prev;
}
}
+/**
+ * Returns last backtracking point. The model checker will explore a different
+ * path for this point in the next execution.
+ * @return The ModelAction at which the next execution should diverge.
+ */
ModelAction * ModelChecker::get_next_backtrack()
{
ModelAction *next = next_backtrack;
void ModelChecker::check_current_action(void)
{
- Node *currnode;
-
ModelAction *curr = this->current_action;
- ModelAction *tmp;
- current_action = NULL;
+ bool already_added = false;
+ this->current_action = NULL;
if (!curr) {
DEBUG("trying to push NULL action...\n");
return;
}
- tmp = node_stack->explore_action(curr);
- if (tmp) {
- /* Discard duplicate ModelAction; use action from NodeStack */
+ if (curr->is_rmwc()||curr->is_rmw()) {
+ ModelAction *tmp=process_rmw(curr);
+ already_added = true;
delete curr;
- curr = tmp;
+ curr=tmp;
} else {
- /*
- * Perform one-time actions when pushing new ModelAction onto
- * NodeStack
- */
- curr->create_cv(get_parent_action(curr->get_tid()));
- /* Build may_read_from set */
- if (curr->is_read())
- build_reads_from_past(curr);
+ ModelAction * tmp = node_stack->explore_action(curr);
+ if (tmp) {
+ /* Discard duplicate ModelAction; use action from NodeStack */
+ /* First restore type and order in case of RMW operation */
+ if (curr->is_rmwr())
+ tmp->copy_typeandorder(curr);
+ delete curr;
+ curr = tmp;
+ } else {
+ /*
+ * Perform one-time actions when pushing new ModelAction onto
+ * NodeStack
+ */
+ curr->create_cv(get_parent_action(curr->get_tid()));
+ /* Build may_read_from set */
+ if (curr->is_read())
+ build_reads_from_past(curr);
+ if (curr->is_write())
+ compute_promises(curr);
+ }
}
/* Assign 'creation' parent */
th->set_creation(curr);
}
- nextThread = get_next_replay_thread();
+ /* Deal with new thread */
+ if (curr->get_type() == THREAD_START) {
+ check_promises(NULL, curr->get_cv());
+ }
+
+ /* Assign reads_from values */
+ Thread *th = get_thread(curr->get_tid());
+ uint64_t value = VALUE_NONE;
+ if (curr->is_read()) {
+ const ModelAction *reads_from = curr->get_node()->get_read_from();
+ if (reads_from!=NULL) {
+ value = reads_from->get_value();
+ /* Assign reads_from, perform release/acquire synchronization */
+ curr->read_from(reads_from);
+ r_modification_order(curr,reads_from);
+ } else {
+ /* Read from future value */
+ value = curr->get_node()->get_future_value();
+ curr->read_from(NULL);
+ Promise * valuepromise=new Promise(curr, value);
+ promises->push_back(valuepromise);
+ }
+ } else if (curr->is_write()) {
+ w_modification_order(curr);
+ resolve_promises(curr);
+ }
+
+ th->set_return_value(value);
+
+ /* Add action to list. */
+ if (!already_added)
+ add_action_to_lists(curr);
- currnode = curr->get_node()->get_parent();
+ /* Is there a better interface for setting the next thread rather
+ than this field/convoluted approach? Perhaps like just returning
+ it or something? */
- if (!currnode->backtrack_empty())
+ /* Do not split atomic actions. */
+ if (curr->is_rmwr()) {
+ nextThread = thread_current()->get_id();
+ } else {
+ nextThread = get_next_replay_thread();
+ }
+
+ Node *currnode = curr->get_node();
+ Node *parnode = currnode->get_parent();
+
+ if (!parnode->backtrack_empty()||!currnode->readsfrom_empty()||!currnode->futurevalues_empty()||!currnode->promises_empty())
if (!next_backtrack || *curr > *next_backtrack)
next_backtrack = curr;
-
+
set_backtracking(curr);
+}
- add_action_to_lists(curr);
+/** @returns whether the current trace is feasible. */
+bool ModelChecker::isfeasible() {
+ return !cyclegraph->checkForCycles() && !failed_promise;
+}
+
+/** Close out a RMWR by converting previous RMWR into a RMW or READ. */
+ModelAction * ModelChecker::process_rmw(ModelAction * act) {
+ int tid = id_to_int(act->get_tid());
+ ModelAction *lastread=get_last_action(tid);
+ lastread->process_rmw(act);
+ if (act->is_rmw())
+ cyclegraph->addRMWEdge(lastread, lastread->get_reads_from());
+ return lastread;
+}
+
+/**
+ * Updates the cyclegraph with the constraints imposed from the current read.
+ * @param curr The current action. Must be a read.
+ * @param rf The action that curr reads from. Must be a write.
+ */
+void ModelChecker::r_modification_order(ModelAction * curr, const ModelAction *rf) {
+ std::vector<action_list_t> *thrd_lists = obj_thrd_map->ensureptr(curr->get_location());
+ unsigned int i;
+ ASSERT(curr->is_read());
+
+ /* Iterate over all threads */
+ for (i = 0; i < thrd_lists->size(); i++) {
+ /* Iterate over actions in thread, starting from most recent */
+ action_list_t *list = &(*thrd_lists)[i];
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
+ ModelAction *act = *rit;
+
+ /* Include at most one act per-thread that "happens before" curr */
+ if (act->happens_before(curr)) {
+ if (act->is_read()) {
+ const ModelAction * prevreadfrom=act->get_reads_from();
+ if (rf!=prevreadfrom)
+ cyclegraph->addEdge(rf, prevreadfrom);
+ } else if (rf!=act) {
+ cyclegraph->addEdge(rf, act);
+ }
+ break;
+ }
+ }
+ }
+}
+
+/**
+ * Updates the cyclegraph with the constraints imposed from the current write.
+ * @param curr The current action. Must be a write.
+ */
+void ModelChecker::w_modification_order(ModelAction * curr) {
+ std::vector<action_list_t> *thrd_lists = obj_thrd_map->ensureptr(curr->get_location());
+ unsigned int i;
+ ASSERT(curr->is_write());
+
+ if (curr->is_seqcst()) {
+ /* We have to at least see the last sequentially consistent write,
+ so we are initialized. */
+ ModelAction * last_seq_cst=get_last_seq_cst(curr->get_location());
+ if (last_seq_cst!=NULL)
+ cyclegraph->addEdge(curr, last_seq_cst);
+ }
+
+ /* Iterate over all threads */
+ for (i = 0; i < thrd_lists->size(); i++) {
+ /* Iterate over actions in thread, starting from most recent */
+ action_list_t *list = &(*thrd_lists)[i];
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
+ ModelAction *act = *rit;
+
+ /* Include at most one act per-thread that "happens before" curr */
+ if (act->happens_before(curr)) {
+ if (act->is_read()) {
+ cyclegraph->addEdge(curr, act->get_reads_from());
+ } else
+ cyclegraph->addEdge(curr, act);
+ break;
+ } else {
+ if (act->is_read()&&!act->is_synchronizing(curr)&&!act->same_thread(curr)) {
+ /* We have an action that:
+ (1) did not happen before us
+ (2) is a read and we are a write
+ (3) cannot synchronize with us
+ (4) is in a different thread
+ =>
+ that read could potentially read from our write.
+ */
+
+ if (act->get_node()->add_future_value(curr->get_value())&&
+ (!next_backtrack || *act > * next_backtrack))
+ next_backtrack = act;
+ }
+ }
+ }
+ }
}
/**
*/
void ModelChecker::add_action_to_lists(ModelAction *act)
{
+ int tid = id_to_int(act->get_tid());
action_trace->push_back(act);
- std::vector<action_list_t> *vec = &(*obj_thrd_map)[act->get_location()];
- if (id_to_int(act->get_tid()) >= (int)vec->size())
+ obj_map->ensureptr(act->get_location())->push_back(act);
+
+ std::vector<action_list_t> *vec = obj_thrd_map->ensureptr(act->get_location());
+ if (tid >= (int)vec->size())
vec->resize(next_thread_id);
- (*vec)[id_to_int(act->get_tid())].push_back(act);
+ (*vec)[tid].push_back(act);
- (*thrd_last_action)[id_to_int(act->get_tid())] = act;
+ if ((int)thrd_last_action->size() <= tid)
+ thrd_last_action->resize(get_num_threads());
+ (*thrd_last_action)[tid] = act;
}
ModelAction * ModelChecker::get_last_action(thread_id_t tid)
return (*thrd_last_action)[id_to_int(tid)];
}
+/**
+ * Gets the last memory_order_seq_cst action (in the total global sequence)
+ * performed on a particular object (i.e., memory location).
+ * @param location The object location to check
+ * @return The last seq_cst action performed
+ */
+ModelAction * ModelChecker::get_last_seq_cst(const void *location)
+{
+ action_list_t *list = obj_map->ensureptr(location);
+ /* Find: max({i in dom(S) | seq_cst(t_i) && isWrite(t_i) && samevar(t_i, t)}) */
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++)
+ if ((*rit)->is_write() && (*rit)->is_seqcst())
+ return *rit;
+ return NULL;
+}
+
ModelAction * ModelChecker::get_parent_action(thread_id_t tid)
{
ModelAction *parent = get_last_action(tid);
return parent;
}
+/**
+ * Returns the clock vector for a given thread.
+ * @param tid The thread whose clock vector we want
+ * @return Desired clock vector
+ */
+ClockVector * ModelChecker::get_cv(thread_id_t tid) {
+ return get_parent_action(tid)->get_cv();
+}
+
+
+/** Resolve promises. */
+
+void ModelChecker::resolve_promises(ModelAction *write) {
+ for(unsigned int i=0;i<promises->size();i++) {
+ Promise * promise=(*promises)[i];
+ if (write->get_node()->get_promise(i)) {
+ ModelAction * read=promise->get_action();
+ read->read_from(write);
+ r_modification_order(read, write);
+ }
+ }
+}
+
+void ModelChecker::compute_promises(ModelAction *curr) {
+ for(unsigned int i=0;i<promises->size();i++) {
+ Promise * promise=(*promises)[i];
+ const ModelAction * act=promise->get_action();
+ if (!act->happens_before(curr)&&
+ act->is_read()&&
+ !act->is_synchronizing(curr)&&
+ !act->same_thread(curr)&&
+ promise->get_value()==curr->get_value()) {
+ curr->get_node()->set_promise(i);
+ }
+ }
+}
+
+/** Checks promises in response to change in ClockVector Threads. */
+
+void ModelChecker::check_promises(ClockVector *old_cv, ClockVector * merge_cv) {
+ for(unsigned int i=0;i<promises->size();i++) {
+ Promise * promise=(*promises)[i];
+ const ModelAction * act=promise->get_action();
+ if ((old_cv==NULL||!old_cv->synchronized_since(act))&&
+ merge_cv->synchronized_since(act)) {
+ //This thread is no longer able to send values back to satisfy the promise
+ int num_synchronized_threads=promise->increment_threads();
+ if (num_synchronized_threads==model->get_num_threads()) {
+ //Promise has failed
+ failed_promise = true;
+ return;
+ }
+ }
+ }
+}
+
/**
* Build up an initial set of all past writes that this 'read' action may read
* from. This set is determined by the clock vector's "happens before"
*/
void ModelChecker::build_reads_from_past(ModelAction *curr)
{
- std::vector<action_list_t> *thrd_lists = &(*obj_thrd_map)[curr->get_location()];
+ std::vector<action_list_t> *thrd_lists = obj_thrd_map->ensureptr(curr->get_location());
unsigned int i;
-
ASSERT(curr->is_read());
+ ModelAction *last_seq_cst = NULL;
+
/* Track whether this object has been initialized */
bool initialized = false;
+ if (curr->is_seqcst()) {
+ last_seq_cst = get_last_seq_cst(curr->get_location());
+ /* We have to at least see the last sequentially consistent write,
+ so we are initialized. */
+ if (last_seq_cst != NULL)
+ initialized = true;
+ }
+
+ /* Iterate over all threads */
for (i = 0; i < thrd_lists->size(); i++) {
+ /* Iterate over actions in thread, starting from most recent */
action_list_t *list = &(*thrd_lists)[i];
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *act = *rit;
-
+
/* Only consider 'write' actions */
if (!act->is_write())
continue;
- DEBUG("Adding action to may_read_from:\n");
- if (DBG_ENABLED()) {
- act->print();
- curr->print();
+ /* Don't consider more than one seq_cst write if we are a seq_cst read. */
+ if (!act->is_seqcst() || !curr->is_seqcst() || act == last_seq_cst) {
+ DEBUG("Adding action to may_read_from:\n");
+ if (DBG_ENABLED()) {
+ act->print();
+ curr->print();
+ }
+ curr->get_node()->add_read_from(act);
}
- curr->get_node()->add_read_from(act);
/* Include at most one act per-thread that "happens before" curr */
if (act->happens_before(curr)) {
}
if (!initialized) {
- /* TODO: need a more informative way of reporting errors */
+ /** @todo Need a more informative way of reporting errors. */
printf("ERROR: may read from uninitialized atomic\n");
}
scheduler->print();
+ if (!isfeasible())
+ printf("INFEASIBLE EXECUTION!\n");
print_list(action_trace);
printf("\n");
}
int ModelChecker::add_thread(Thread *t)
{
- (*thread_map)[id_to_int(t->get_id())] = t;
+ thread_map->put(id_to_int(t->get_id()), t);
scheduler->add_thread(t);
return 0;
}
scheduler->remove_thread(t);
}
+/**
+ * Switch from a user-context to the "master thread" context (a.k.a. system
+ * context). This switch is made with the intention of exploring a particular
+ * model-checking action (described by a ModelAction object). Must be called
+ * from a user-thread context.
+ * @param act The current action that will be explored. May be NULL, although
+ * there is little reason to switch to the model-checker without an action to
+ * explore (note: act == NULL is sometimes used as a hack to allow a thread to
+ * yield control without performing any progress; see thrd_join()).
+ * @return Return status from the 'swap' call (i.e., success/fail, 0/-1)
+ */
int ModelChecker::switch_to_master(ModelAction *act)
{
- Thread *old;
-
DBG();
- old = thread_current();
+ Thread * old = thread_current();
set_current_action(act);
old->set_state(THREAD_READY);
return Thread::swap(old, get_system_context());
projects / c11tester.git / blobdiff