MVar *ComparisonStageIR::compute_linear_index(MVar *left_idx, MVar *right_bound, MVar *right_idx, MBlock *block) const {
MMul *mul = new MMul(left_idx, right_bound);
mul->register_for_delete();
block->add_expr(mul);
MAdd *add = new MAdd(mul->get_result(), right_idx);
add->register_for_delete();
block->add_expr(add);
return add->get_result();
}
void ComparisonStageIR::build_stage() {
assert(!is_tiled() || (is_tiled() && !track_progress()));
// timer is only allowed for serial loops (just use it to get avg iterations per second or something like that)
assert(!time_loop() || (time_loop() && !is_parallelized()));
set_stage_function(create_stage_function());
set_user_function(create_user_function());
// stuff before the loop
// build the return idx
MVar *loop_start = new MVar(MScalarType::get_long_type()); // don't make a constant b/c it should be updateable
loop_start->register_for_delete();
MStatement *set_loop_start = new MStatement(loop_start, MVar::create_constant<long>(0));
set_loop_start->register_for_delete();
MStatement *set_result = new MStatement(get_return_idx(), loop_start);
set_result->register_for_delete();
set_start_block(new MBlock("start"));
get_start_block()->register_for_delete();
get_start_block()->add_expr(set_loop_start);
get_start_block()->add_expr(set_result);
// When we don't parallelize, then make the inner loop's index outside of both the loops rather than within
// the outer loop. This is a hack for llvm because if we have an alloca call within each iteration of the outer loop,
// we will be "leaking" stack space each time that is called, so moving it outside of the loop prevents that.
// However, it makes it hard to work with when we then parallelize because the code sees that inner loop index as a
// free variable that needs to be added to the closure. This is not fun because our index is now a pointer to an index
// and then we would need to update the index by going through the pointer, etc. Basically, it would cause some hacks on the
// LLVM side (and unless this becomes something that is needed in the future, I don't want to deal with it).
// So instead, it is dealt with below. Without parallelization, the inner loop index is initialized outside of the
// nested loop, and then updated to the correct start right before the inner loop begins execution.
// When parallelization is turned on, the inner loop index is made INSIDE the outer loop. This is because the
// parallelized outer loop calls a function every iteration which is the outer loop body, and then within that the
// inner loop is created. alloca is scoped at the function level, so the inner loop index gets a single alloca
// in this function call, and then the inner loop is created.
// This may not be required of other possible back-end languages that we choose, but it will depend on their scoping rules.
//
// TL;DR LLVM has function scoping for allocainst, so if we create the inner loop index as so
// val outer_index...
// for outer_index...
// val inner_index...
// for inner_index...
// every iteration of the outer loop adds space to the stack which isn't released until the function ends. So we want
// val outer_index...
// val inner_index...
// for outer_index...
// for inner_index...
MVar *inner_start = initialize<long>(MScalarType::get_long_type(), 0, get_start_block());
MBlock *preallocation_block = create_preallocator();
get_start_block()->add_expr(preallocation_block);
MTimer *timer = nullptr;
timer = new MTimer();
timer->register_for_delete();
MFor *outer_loop_skeleton_1 = nullptr;
MFor *inner_loop_skeleton_1 = nullptr;
MFor *outer_loop_skeleton_2 = nullptr;
MFor *inner_loop_skeleton_2 = nullptr;
MBlock *inner_loop_body = nullptr;
// think of all comparisons as being in an NxM matrix where N is the left input and M is the right input.
// N is the outermost iteration
tile_size_N = MVar::create_constant<long>(2);
tile_size_M = MVar::create_constant<long>(2);
MVar *final_loop_bound;
if (!is_tiled() || !is_tileable()) { // No tiling
// To make sure that the inner loop doesn't get replace with a different bound if parallelizing, copy
// the bound to a different variable and use that
MVar *bound_copy = new MVar(MScalarType::get_long_type());
bound_copy->register_for_delete();
MStatement *set_copy = new MStatement(bound_copy, get_stage_function()->/*get_args()*/get_loaded_args()[3]);
set_copy->register_for_delete();
get_start_block()->add_expr(set_copy);
// loop components
MVar *outer_loop_start = initialize<long>(MScalarType::get_long_type(), 0, get_start_block());
outer_loop_skeleton_1 =
create_stage_for_loop(outer_loop_start, MVar::create_constant<long>(1),
get_stage_function()->/*get_args()*/get_loaded_args()[1], false, get_start_block());
if (is_parallelizable() && is_parallelized()) {
outer_loop_skeleton_1->set_exec_type(PARALLEL);
}
MVar *_inner_start = nullptr;
if ((left_input || right_input) && !_force_commutative) {
_inner_start = initialize<long>(MScalarType::get_long_type(), 0, get_start_block());
} else {
MAdd *add = new MAdd(outer_loop_skeleton_1->get_loop_index(),
MVar::create_constant<long>(1));
outer_loop_skeleton_1->get_body_block()->add_expr(add);
add->register_for_delete();
_inner_start = add->get_result();
}
if (!time_loop()) {
get_start_block()->add_expr(outer_loop_skeleton_1);
} else {
get_start_block()->add_expr(timer);
timer->get_timer_block()->add_expr(outer_loop_skeleton_1);
}
MStatement *set_inner_start = new MStatement(inner_start, _inner_start);
set_inner_start->register_for_delete();
outer_loop_skeleton_1->get_body_block()->add_expr(set_inner_start);
MBlock *temp_block = new MBlock();
temp_block->register_for_delete();
inner_loop_skeleton_1 = create_stage_for_loop(inner_start, MVar::create_constant<long>(1), bound_copy, true,
temp_block);
// TODO hack, need to add the loop index initialization before the outer loop, but we have to add the outer loop before this since
// the inner_start depends on the outer loop
get_start_block()->insert_at(temp_block, get_start_block()->get_exprs().size() - 2); // insert right before the outer loop
// stuff for calling the user function in the loop
inner_loop_body = inner_loop_skeleton_1->get_body_block();
} else if (is_tiled() && is_tileable()) { // tiling
// loop components
MDiv *_outer_1_bound =
new MDiv(get_stage_function()->/*get_args()*/get_loaded_args()[1], tile_size_N);
_outer_1_bound->register_for_delete();
MDiv *_inner_1_bound =
new MDiv(get_stage_function()->/*get_args()*/get_loaded_args()[3], tile_size_M);
_inner_1_bound->register_for_delete();
// compensate for when the number of elements isn't a multiple of the tile size
MAdd *outer_1_bound = new MAdd(_outer_1_bound->get_result(), MVar::create_constant<long>(1));
outer_1_bound->register_for_delete();
MAdd *inner_1_bound = new MAdd(_inner_1_bound->get_result(), MVar::create_constant<long>(1));
inner_1_bound->register_for_delete();
get_start_block()->add_expr(_outer_1_bound);
get_start_block()->add_expr(_inner_1_bound);
get_start_block()->add_expr(outer_1_bound);
get_start_block()->add_expr(inner_1_bound);
MVar *outer_loop_start_1 = initialize<long>(MScalarType::get_long_type(), 0, get_start_block());
outer_loop_start_1->override_name("outer_loop_start_1");
MVar *inner_loop_start_1 = initialize<long>(MScalarType::get_long_type(), 0, get_start_block());
inner_loop_start_1->override_name("inner_loop_start_1");
MVar *outer_loop_start_2 = initialize<long>(MScalarType::get_long_type(), 0, get_start_block());
outer_loop_start_2->override_name("outer_loop_start_2");
MVar *inner_loop_start_2 = initialize<long>(MScalarType::get_long_type(), 0, get_start_block());
inner_loop_start_2->override_name("inner_loop_start_2");
// n = 0 to N/tile_size_N + 1
outer_loop_skeleton_1 =
create_stage_for_loop(outer_loop_start_1, MVar::create_constant<long>(1),
outer_1_bound->get_result(), true, get_start_block());
outer_loop_skeleton_1->override_name("outer_loop_skeleton1");
//
// if (!time_loop()) {
// get_start_block()->add_expr(outer_loop_skeleton_1);
// } else {
// get_start_block()->add_expr(timer);
// timer->get_timer_block()->add_expr(outer_loop_skeleton_1);
// }
// m = 0 to M/tile_size_M + 1
inner_loop_skeleton_1 =
create_stage_for_loop(inner_loop_start_1, MVar::create_constant<long>(1),
inner_1_bound->get_result(), true, get_start_block());
inner_loop_skeleton_1->override_name("inner_loop_skeleton1");
// nn = 0 to tile_size_N
outer_loop_skeleton_2 = create_stage_for_loop(outer_loop_start_2, MVar::create_constant<long>(1),
tile_size_N, true, get_start_block());
outer_loop_skeleton_2->override_name("outer_loop_skeleton2");
// mm = 0 to tile_size_M
inner_loop_skeleton_2 = create_stage_for_loop(inner_loop_start_2, MVar::create_constant<long>(1),
tile_size_M, true, get_start_block());
inner_loop_skeleton_2->override_name("inner_loop_skeleton2");
if (!time_loop()) {
get_start_block()->add_expr(outer_loop_skeleton_1);
} else {
get_start_block()->add_expr(timer);
timer->get_timer_block()->add_expr(outer_loop_skeleton_1);
}
inner_loop_skeleton_1->get_body_block()->add_expr(outer_loop_skeleton_2);
outer_loop_skeleton_2->get_body_block()->add_expr(inner_loop_skeleton_2);
inner_loop_body = inner_loop_skeleton_2->get_body_block();
}
MBlock *user_arg_block;
std::vector<MVar *> args = create_user_function_inputs(&user_arg_block, outer_loop_skeleton_1, outer_loop_skeleton_2,
inner_loop_skeleton_1, inner_loop_skeleton_2, nullptr, false,
nullptr, nullptr, get_stage_function()->/*get_args()*/get_loaded_args()[1],
get_stage_function()->/*get_args()*/get_loaded_args()[3]);
if (!is_tiled() || !is_tileable()) {
inner_loop_body->add_expr(user_arg_block);
} // if tiled, this is already added in the create_user_function_inputs
inner_loop_body = user_arg_block;
int bucket_idx = inner_loop_body->get_exprs().size();
MFunctionCall *call = call_user_function(get_user_function(), args);
inner_loop_body->add_expr(call);
// handle the output of the user call
MBlock *processed_call = process_user_function_call(call, NULL, false);
inner_loop_body->add_expr(processed_call);
// do any other postprocessing needed in the loop before the next iteration
MBlock *extra = loop_extras();
inner_loop_body->add_expr(extra);
if (track_progress() && !is_parallelized()) {
// still return the original loop bound
MBlock *temp = new MBlock();
temp->register_for_delete();
final_loop_bound = outer_loop_skeleton_1->get_loop_bound();
outer_loop_skeleton_1->get_body_block()->add_expr(inner_loop_skeleton_1);
inner_loop_body->insert_at(apply_buckets(args[0], args[1], inner_loop_skeleton_2 ? inner_loop_skeleton_2 : inner_loop_skeleton_1), bucket_idx);
std::pair<MFor *, MFor *> splits = ProgressTracker::create_progress_tracker(outer_loop_skeleton_1,
inner_loop_skeleton_1,
get_num_tracking_splits(), temp,
true);
// find the original outer_loop_skeleton_1 in the block and remove it. Then replace with the new one in splits.first
int idx = 0;
if (!time_loop()) {
for (std::vector<MExpr *>::const_iterator iter = get_start_block()->get_exprs().cbegin();
iter != get_start_block()->get_exprs().cend(); iter++) {
if (*iter == outer_loop_skeleton_1) {
break;
}
idx++;
}
get_start_block()->remove_at(idx);
} else {
for (std::vector<MExpr *>::const_iterator iter = timer->get_timer_block()->get_exprs().cbegin();
iter != timer->get_timer_block()->get_exprs().cend(); iter++) {
if (*iter == outer_loop_skeleton_1) {
break;
}
idx++;
}
timer->get_timer_block()->remove_at(idx);
}
outer_loop_skeleton_1 = splits.first;
// do the replacement
// outer_loop_skeleton_1 added to temp block in the progress tracker function
if (!time_loop()) {
get_stage_function()->add_body_block(temp);
} else {
timer->get_timer_block()->insert_at(temp, idx);
}
} else {
outer_loop_skeleton_1->get_body_block()->add_expr(inner_loop_skeleton_1);
final_loop_bound = outer_loop_skeleton_1->get_loop_bound();
inner_loop_body->insert_at(apply_buckets(args[0], args[1], inner_loop_skeleton_2 ? inner_loop_skeleton_2 : inner_loop_skeleton_1), bucket_idx);
}
// modify this loop if it needs to be parallelized
if (is_parallelizable() && is_parallelized()) {
parallelize_main_loop(get_start_block(), outer_loop_skeleton_1, inner_loop_skeleton_1);
}
//
// if (is_tiled() && is_tileable()) {
// inner_loop_skeleton_1->get_body_block()->add_expr(outer_loop_skeleton_2);
// outer_loop_skeleton_2->get_body_block()->add_expr(inner_loop_skeleton_2);
// }
// postprocessing after the outer loop is done (no postprocessing needed after the inner loop since it just goes back to the outer loop)
MBlock *after_loop = time_loop() ? timer->get_after_timer_block() : outer_loop_skeleton_1->get_end_block();
MBlock *finished = finish_stage(nullptr, final_loop_bound);
MBlock *deletion = delete_fields();
after_loop->add_expr(deletion);
after_loop->add_expr(finished);
get_stage_function()->insert_body_block_at(get_start_block(), 1); // insert before the temp block, which would have been added if doing tracking. Insert after the stage arg loading though.
// the temp block has the loop now, so it can't come before everything else
}
// TODO once I get the indexing right, I can fix preallocation so that only the correct number of outputs are preallocated, not just N^2
// TODO Can also fix the number output (does that need to be fixed?)
std::vector<MVar *> ComparisonStageIR::create_user_function_inputs(MBlock **mblock, MFor *outer_loop,
MFor *outer_tiled_inner,
MFor *inner_loop, MFor *inner_tiled_inner, MVar *,
bool, MVar *, MVar *,
MVar *original_num_inputs_left,
MVar *original_num_inputs_right) {
// body of the outer MFor passed in is the inner MFor loop
std::vector<MVar *> stage_args = get_stage_function()->get_loaded_args();//get_args();
std::vector<MVar *> args;
// Think of the indices into the two input arrays as coordinates into a matrix. The outer coordinate is for N, i.e. the row number.
// The inner coordinate is for M, i.e. the column number.
MVar *final_outer_coordinate;
MVar *final_inner_coordinate;
// get the outer and inner input elements
// if tiled, the computation for the indices is different
if (is_tiled() && is_tileable()) {
if ((left_input || right_input) && !_force_commutative) { // N x M
assert(original_num_inputs_left && original_num_inputs_right); // sanity check
MVar *n = outer_loop->get_loop_index();
MVar *m = inner_loop->get_loop_index();
MVar *nn = outer_tiled_inner->get_loop_index();
MVar *mm = inner_tiled_inner->get_loop_index();
// outer = n * tile_size_N + nn
final_outer_coordinate = get_element(stage_args[0], n, tile_size_N, nn, outer_tiled_inner->get_body_block(),
inner_loop, &args, original_num_inputs_left, nullptr);
// inner = m * M + mm
final_inner_coordinate = get_element(stage_args[2], m, tile_size_M, mm, inner_tiled_inner->get_body_block(),
outer_tiled_inner, &args, original_num_inputs_right, mblock);
} else { // (N^2-N)/2
assert(original_num_inputs_left && original_num_inputs_right); // sanity check
MVar *n = outer_loop->get_loop_index();
MVar *m = inner_loop->get_loop_index();
MVar *nn = outer_tiled_inner->get_loop_index();
MVar *mm = inner_tiled_inner->get_loop_index();
// outer = n * tile_size_N + nn
final_outer_coordinate = get_element(stage_args[0], n, tile_size_N, nn, outer_tiled_inner->get_body_block(),
inner_loop, &args, original_num_inputs_left, nullptr); // the outer doesn't change with commutativity
// this code could almost be handled by get_element, but the conditional is more complex, so I just leave it here for now rather than
// trying to refactor it.
// inner = m * M + mm
int inner_insert_idx = 0;
MBlock *linear_inner = new MBlock();
linear_inner->register_for_delete();
MVar *inner_idx = compute_linear_index(m, tile_size_M, mm, linear_inner);
inner_tiled_inner->get_body_block()->insert_at(linear_inner, inner_insert_idx++);
final_inner_coordinate = inner_idx;
// check that the inner index is still in range (< M) and that it is less than the outer idx
// TODO this assumes that the integral value of true is 1. In the future, create an MTrue and MFalse type
// that allows arithmetic to be done on it. Then I can plug in the actual values when generating the back end code, such as LLVM.
MSLT *is_inner_in_range = new MSLT(inner_idx, original_num_inputs_right);
is_inner_in_range->register_for_delete();
inner_tiled_inner->get_body_block()->insert_at(is_inner_in_range, inner_insert_idx++);
MSLT *is_less_than_outer = new MSLT(inner_idx, final_outer_coordinate);
is_less_than_outer->register_for_delete();
is_less_than_outer->override_name("inner_less_than_outer");
inner_tiled_inner->get_body_block()->insert_at(is_less_than_outer, inner_insert_idx++);
// since we don't have a compound conditional type (YET), we get the results of the two SLT calls here.
// If they sum to 2, then both are true since we assume true == 1. This way, we only need a single if
// statement checking the value of the addition.
MCast *is_inner_in_range_long = new MCast(is_inner_in_range->get_result(), MScalarType::get_long_type());
is_inner_in_range_long->register_for_delete();
inner_tiled_inner->get_body_block()->insert_at(is_inner_in_range_long, inner_insert_idx++);
MCast *is_less_than_outer_long = new MCast(is_less_than_outer->get_result(), MScalarType::get_long_type());
is_less_than_outer_long->register_for_delete();
inner_tiled_inner->get_body_block()->insert_at(is_less_than_outer_long, inner_insert_idx++);
MAdd *sum_of_conditionals = new MAdd(is_inner_in_range_long->get_casted(), is_less_than_outer_long->get_casted());
sum_of_conditionals->register_for_delete();
inner_tiled_inner->get_body_block()->insert_at(sum_of_conditionals, inner_insert_idx++);
MEq *is_in_range_and_less_than = new MEq(sum_of_conditionals->get_result(), MVar::create_constant<long>(2));
is_in_range_and_less_than->register_for_delete();
inner_tiled_inner->get_body_block()->insert_at(is_in_range_and_less_than, inner_insert_idx++);
MBlock *inner_is_in_range_and_less_than = new MBlock();
inner_is_in_range_and_less_than->register_for_delete();
MBlock *inner_not_in_range_nor_less_than = new MBlock();
inner_not_in_range_nor_less_than->register_for_delete();
MBlock *dummy_inner = new MBlock();
dummy_inner->register_for_delete();
MIfThenElse *inner_ite = new MIfThenElse(is_in_range_and_less_than->get_result(), inner_is_in_range_and_less_than,
inner_not_in_range_nor_less_than, dummy_inner, nullptr);
inner_ite->register_for_delete();
inner_tiled_inner->get_body_block()->insert_at(inner_ite, inner_insert_idx++);
inner_ite->override_name("inner_ite");
// If in range, get the inner element and then go to the innermost tiled loop.
// Since the innermost loop is already in outer_tiled_inner's body, remove it from there (and any other stuff that should only
// execute if the we are in range) and then add it to the outer_is_in_range block.
MIndex *get_inner_input = new MIndex(stage_args[2], inner_idx, create_type<MElementType *>(),
"inner_input_element");
get_inner_input->register_for_delete();
inner_is_in_range_and_less_than->add_expr(get_inner_input);
args.push_back(get_inner_input->get_result());
inner_is_in_range_and_less_than->add_exprs(inner_tiled_inner->get_body_block()->remove_range(inner_insert_idx++, -1));
// If out of range, continue to the next iteration of the outer_tiled_inner_loop
MContinue *to_nn_loop = new MContinue(outer_tiled_inner);
to_nn_loop->register_for_delete();
inner_not_in_range_nor_less_than->add_expr(to_nn_loop);
*mblock = inner_is_in_range_and_less_than;
}
} else { // the loop indices are already setup by this point depending on whether we are NxM or N^2
MVar *current_outer_idx = outer_loop->get_loop_index();
MVar *current_inner_idx = inner_loop->get_loop_index();
final_outer_coordinate = current_outer_idx;
final_inner_coordinate = current_inner_idx;
MIndex *outer_element = new MIndex(stage_args[0], current_outer_idx, create_type<MElementType *>(),
"outer_input_element");
outer_element->register_for_delete();
MIndex *inner_element = new MIndex(stage_args[2], current_inner_idx, create_type<MElementType *>(),
"inner_input_element");
inner_element->register_for_delete();
outer_loop->get_body_block()->add_expr(outer_element);
inner_loop->get_body_block()->add_expr(inner_element);
args.push_back(outer_element->get_result());
args.push_back(inner_element->get_result());
*mblock = new MBlock();
(*mblock)->register_for_delete();
}
// if this has an output, make the output element
// this doesn't care if we are tiled or not. The equations are the same since we appropriately set the coordinates
// above based on tiling or not.
MVar *final_index;
if (compareVIO) {
// First create "shell" for a new Element* to be passed to the user
MVar *new_element = new MVar(create_type<MElementType*>(), "output_element");
new_element->register_for_delete();
// create the statement that will actually initialize the value
// compute the current output index
if ((left_input || right_input) && !_force_commutative) { // N x M
// equation for linearizing the coordinates is:
// final_outer_coordinate X original_num_inputs_right + final_inner_coordinate
MMul *mul = new MMul(final_outer_coordinate, original_num_inputs_right);
mul->register_for_delete();
(*mblock)->add_expr(mul);
MAdd *add = new MAdd(mul->get_result(), final_inner_coordinate);
add->register_for_delete();
(*mblock)->add_expr(add);
final_index = add->get_result();
} else { // N^2 and/or commutative
// equation for linearizing the coordinates is:
// [final_outer_coordinate^2 - final_outer_coordinate]/2 + final_inner_coordinate
// the division term in this equation tells you how many elements have come before you. Then the addition
// adds on your position in the current row.
// It's not straightforward like the NxM version because we are only doing comparisons between elements
// in the lower triangular part of the matrix (excluding the diagonal), so the linear indices from
// the NxM version would give non-consecutive indices. This basically takes those indices and compresses
// them down from 0 to however many comparisons we do.
MMul *squared = new MMul(final_outer_coordinate, final_outer_coordinate);
squared->register_for_delete();
(*mblock)->add_expr(squared);
MSub *sub = new MSub(squared->get_result(), final_outer_coordinate);
sub->register_for_delete();
(*mblock)->add_expr(sub);
MDiv *div = new MDiv(sub->get_result(), MVar::create_constant<long>(2));
div->register_for_delete();
(*mblock)->add_expr(div);
MAdd *add = new MAdd(div->get_result(), final_inner_coordinate);
add->register_for_delete();
(*mblock)->add_expr(add);
final_index = add->get_result();
}
MStatement *set_new_element = new MStatement(new_element, nullptr); // nullptr tells it to create a new value
set_new_element->register_for_delete();
set_new_element->add_parameter(final_index); // this is the id of the Element to be created
(*mblock)->add_expr(set_new_element);
args.push_back(new_element);
// now set the Element in the output array
MStatementIdx *set = new MStatementIdx(stage_args[4], new_element, final_index);
set->register_for_delete();
(*mblock)->add_expr(set);
}
return args;
}