// Notes:
// - Each task receives distinct copy of parent
// - Copy of child is shallow, be careful with `state` member
static long visit(node_t parent)
{
node_t child;
uint64_t *child_descendants = calloc(sizeof(long), parent.num_children);
CILK_C_REDUCER_OPADD(num_descendants, ulong, 0);
uint64_t tmp;
// Spawn children, if any
for (int i = 0; i < parent.num_children; i++) {
child.height = parent.height + 1;
for (int j = 0; j < num_samples; j++) {
rng_spawn(parent.state.state, child.state.state, i);
}
child.num_children = calc_num_children(&child);
child_descendants[i] = _Cilk_spawn visit(child);
}
_Cilk_sync;
CILK_C_REGISTER_REDUCER(num_descendants);
_Cilk_for(int i = 0; i < parent.num_children; i++) {
REDUCER_VIEW(num_descendants) += child_descendants[i];
}
tmp = 1 + REDUCER_VIEW(num_descendants);
CILK_C_UNREGISTER_REDUCER(num_descendants);
return tmp;
}
// Gets the local instance of a trace local variable
void* get_trace_local(tlv_id id) {
int worker_id = 0;
int steal_count = __cilkrts_get_steal_count(&worker_id);
if (worker_id == 0) {
printf("User thread???\n");
exit(1);
} else {
// Shift back from [1, P] to [0, P-1]
worker_id -= 1;
}
worker_table_t* our_table = &worker_tables[worker_id];
if (our_table->wtrace_info[id].steal_count == steal_count &&
our_table->wtrace_info[id].view != NULL) {
return our_table->wtrace_info[id].view;
}
trace_initializer initializer = global_table.gtrace_info[id].initializer;
void* new_view = (*initializer)();
our_table->wtrace_info[id].view = new_view;
tc_add(&REDUCER_VIEW(global_table.gtrace_info[id].reducer), new_view);
our_table->wtrace_info[id].steal_count = steal_count;
return new_view;
}
// Collects all the instances of the variable in the execution strand
trace_collection collect_trace_local(tlv_id id) {
return REDUCER_VIEW(global_table.gtrace_info[id].reducer);
}
return;
}
void board_reducer_identity(void *key, void* value) {
full_board_t* board = (full_board_t*) value;
memcpy(board, &base_board, sizeof(full_board_t));
board->is_identity = true;
}
void board_reducer_destroy(void *key, void *value) {
return;
}
void initialize_reducer() {
full_board_reducer_t reducer = CILK_C_INIT_REDUCER(full_board_t, board_reducer_reduce, board_reducer_identity,
board_reducer_destroy, (full_board_t) { .board = {0}, .pieces = {{0}, {0}}, .pawn_count = {0, 0}, .rank_major = {0}, .file_major = {0}, .ply = 0, .is_identity = 0});
CILK_C_REDUCER_OPADD(ncr, ulong, 0);
node_count_reducer = ncr;
board_reducer = reducer;
CILK_C_REGISTER_REDUCER(board_reducer);
board_reducer_identity(NULL, &REDUCER_VIEW(board_reducer));
REDUCER_VIEW(board_reducer).is_identity = false;
}
void destroy_reducer() {
CILK_C_UNREGISTER_REDUCER(board_reducer);
CILK_C_UNREGISTER_REDUCER(node_count_reducer);
}
#include "./end_game.c"
static score_t scout_search(searchNode *node, int depth,
uint64_t *node_count_serial, full_board_t* board) {
// Initialize the search node.
initialize_scout_node(node, depth);
// check whether we should abort
if (should_abort_check() || parallel_parent_aborted(node)) {
return 0;
}
// Pre-evaluate this position.
leafEvalResult pre_evaluation_result = evaluate_as_leaf(node, SEARCH_SCOUT, board);
// If we decide to stop searching, return the pre-evaluation score.
if (pre_evaluation_result.type == MOVE_EVALUATED) {
return pre_evaluation_result.score;
}
// Populate some of the fields of this search node, using some
// of the information provided by the pre-evaluation.
int hash_table_move = pre_evaluation_result.hash_table_move;
node->best_score = pre_evaluation_result.score;
node->quiescence = pre_evaluation_result.should_enter_quiescence;
// Grab the killer-moves for later use.
move_t killer_a = killer[KMT(node->ply, 0)];
move_t killer_b = killer[KMT(node->ply, 1)];
// Store the sorted move list on the stack.
// MAX_NUM_MOVES is all that we need.
sortable_move_t move_list[MAX_NUM_MOVES];
// Obtain the sorted move list.
int num_of_moves = get_sortable_move_list(node, move_list, hash_table_move, board);
int num_of_special_moves = move_list[num_of_moves];
int num_of_nonzero_moves = move_list[num_of_moves + 1];
if (num_of_special_moves == 0) {
selectionSort(move_list, num_of_moves, 1);
num_of_special_moves = 1;
}
int number_of_moves_evaluated = 0;
bool generated_early_cutoff = false;
for (int mv_index = 0; mv_index < num_of_special_moves; mv_index++) {
int local_index = number_of_moves_evaluated++;
move_t mv = get_move(move_list[local_index]);
// increase node count
REDUCER_VIEW(node_count_reducer)++;
smallMoveEvaluationResult result = evaluateMove(node, mv, killer_a, killer_b,
SEARCH_SCOUT,
node_count_serial);
if (result.type == MOVE_ILLEGAL || result.type == MOVE_IGNORE) {
continue;
}
if (abortf || parallel_parent_aborted(node)) {
return 0;
}
// A legal move is a move that's not KO, but when we are in quiescence
// we only want to count moves that has a capture.
if (result.type == MOVE_EVALUATED) {
node->legal_move_count++;
}
// process the score. Note that this mutates fields in node.
bool cutoff = search_process_score(node, mv, local_index, &result, SEARCH_SCOUT);
if (cutoff) {
generated_early_cutoff = true;
break;
}
}
// ABOVE IS YOUNG BROTHER'S WAIT CODE. IT SHOULD RUN IN SERIAL
//
// BELOW IS PARALLELIZED SCOUT SEARCH. IT SHOULD RUN IN PARALLEL
// if this happens, we generated an early cutoff in young brother's wait and can just skip to the end
if (generated_early_cutoff)
goto finish_scout_search;
sort_incremental(move_list + num_of_special_moves, num_of_nonzero_moves - num_of_special_moves);
// A simple mutex. See simple_mutex.h for implementation details.
simple_mutex_t node_mutex;
init_simple_mutex(&node_mutex);
// TODO: see if changing this depth is better
if (depth >= 2) {
cilk_for (int mv_index = num_of_special_moves; mv_index < num_of_moves; mv_index++) {
do {
if (node->abort) continue;
int local_index = __sync_fetch_and_add(&number_of_moves_evaluated, 1);
move_t mv = get_move(move_list[local_index]);
// increase node count
REDUCER_VIEW(node_count_reducer)++;
smallMoveEvaluationResult result = evaluateMove(node, mv, killer_a, killer_b,
SEARCH_SCOUT,
node_count_serial);
// TODO: change this to break if we want to abort
if (result.type == MOVE_ILLEGAL || result.type == MOVE_IGNORE) {
continue;
}
if (abortf || parallel_parent_aborted(node)) {
node->abort = true;
continue;
}
// A legal move is a move that's not KO, but when we are in quiescence
// we only want to count moves that has a capture.
if (result.type == MOVE_EVALUATED) {
__sync_fetch_and_add(&node->legal_move_count, 1);
}
bool cutoff = false;
if (result.score > node->best_score) {
simple_acquire(&node_mutex);
// process the score. Note that this mutates fields in node.
cutoff = search_process_score(node, mv, local_index, &result, SEARCH_SCOUT);
simple_release(&node_mutex);
}
if (cutoff) {
node->abort = true;
continue;
}
} while (false);
}
} else {
