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Packer feasible candidates list to priority queue #2993

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122 changes: 45 additions & 77 deletions vpr/src/pack/greedy_candidate_selector.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -216,13 +216,11 @@ ClusterGainStats GreedyCandidateSelector::create_cluster_gain_stats(
// Initialize the cluster gain stats.
ClusterGainStats cluster_gain_stats;
cluster_gain_stats.seed_molecule_id = cluster_seed_mol_id;
cluster_gain_stats.num_feasible_blocks = NOT_VALID;
cluster_gain_stats.has_done_connectivity_and_timing = false;
// TODO: The reason this is being resized and not reserved is due to legacy
// code which should be updated.
cluster_gain_stats.feasible_blocks.resize(packer_opts_.feasible_block_array_size);
for (int i = 0; i < packer_opts_.feasible_block_array_size; i++)
cluster_gain_stats.feasible_blocks[i] = PackMoleculeId::INVALID();
cluster_gain_stats.initial_search_for_feasible_blocks = true;
cluster_gain_stats.num_search_for_feasible_blocks_occured = 0;
cluster_gain_stats.num_search_for_feasible_blocks_occurred_limit = packer_opts_.feasible_block_array_size;
cluster_gain_stats.feasible_blocks.clear();
cluster_gain_stats.tie_break_high_fanout_net = AtomNetId::INVALID();
cluster_gain_stats.explore_transitive_fanout = true;

Expand Down Expand Up @@ -285,8 +283,10 @@ void GreedyCandidateSelector::update_cluster_gain_stats_candidate_success(
AttractGroupId atom_grp_id = attraction_groups.get_atom_attraction_group(blk_id);

/* reset list of feasible blocks */
cluster_gain_stats.num_feasible_blocks = NOT_VALID;
cluster_gain_stats.has_done_connectivity_and_timing = false;
cluster_gain_stats.initial_search_for_feasible_blocks = true;
cluster_gain_stats.num_search_for_feasible_blocks_occured = 0;
cluster_gain_stats.feasible_blocks.clear();
/* TODO: Allow clusters to have more than one attraction group. */
if (atom_grp_id.is_valid())
cluster_gain_stats.attraction_grp_id = atom_grp_id;
Expand Down Expand Up @@ -681,8 +681,7 @@ PackMoleculeId GreedyCandidateSelector::get_next_candidate_for_cluster(
*/

// 1. Find unpacked molecules based on criticality and strong connectedness (connected by low fanout nets) with current cluster
if (cluster_gain_stats.num_feasible_blocks == NOT_VALID) {
cluster_gain_stats.num_feasible_blocks = 0;
if (cluster_gain_stats.initial_search_for_feasible_blocks) {
add_cluster_molecule_candidates_by_connectivity_and_timing(cluster_gain_stats,
cluster_id,
cluster_legalizer,
Expand All @@ -692,31 +691,31 @@ PackMoleculeId GreedyCandidateSelector::get_next_candidate_for_cluster(

if (packer_opts_.prioritize_transitive_connectivity) {
// 2. Find unpacked molecules based on transitive connections (eg. 2 hops away) with current cluster
if (cluster_gain_stats.num_feasible_blocks == 0 && cluster_gain_stats.explore_transitive_fanout) {
if (!cluster_gain_stats.initial_search_for_feasible_blocks && cluster_gain_stats.feasible_blocks.size() == 0 && cluster_gain_stats.explore_transitive_fanout) {
add_cluster_molecule_candidates_by_transitive_connectivity(cluster_gain_stats,
cluster_id,
cluster_legalizer,
attraction_groups);
}

// 3. Find unpacked molecules based on weak connectedness (connected by high fanout nets) with current cluster
if (cluster_gain_stats.num_feasible_blocks == 0 && cluster_gain_stats.tie_break_high_fanout_net) {
if (!cluster_gain_stats.initial_search_for_feasible_blocks && cluster_gain_stats.feasible_blocks.size() == 0 && cluster_gain_stats.tie_break_high_fanout_net) {
add_cluster_molecule_candidates_by_highfanout_connectivity(cluster_gain_stats,
cluster_id,
cluster_legalizer,
attraction_groups);
}
} else { //Reverse order
// 3. Find unpacked molecules based on weak connectedness (connected by high fanout nets) with current cluster
if (cluster_gain_stats.num_feasible_blocks == 0 && cluster_gain_stats.tie_break_high_fanout_net) {
if (!cluster_gain_stats.initial_search_for_feasible_blocks && cluster_gain_stats.feasible_blocks.size() == 0 && cluster_gain_stats.tie_break_high_fanout_net) {
add_cluster_molecule_candidates_by_highfanout_connectivity(cluster_gain_stats,
cluster_id,
cluster_legalizer,
attraction_groups);
}

// 2. Find unpacked molecules based on transitive connections (eg. 2 hops away) with current cluster
if (cluster_gain_stats.num_feasible_blocks == 0 && cluster_gain_stats.explore_transitive_fanout) {
if (!cluster_gain_stats.initial_search_for_feasible_blocks && cluster_gain_stats.feasible_blocks.size() == 0 && cluster_gain_stats.explore_transitive_fanout) {
add_cluster_molecule_candidates_by_transitive_connectivity(cluster_gain_stats,
cluster_id,
cluster_legalizer,
Expand All @@ -725,21 +724,35 @@ PackMoleculeId GreedyCandidateSelector::get_next_candidate_for_cluster(
}

// 4. Find unpacked molecules based on attraction group of the current cluster (if the cluster has an attraction group)
if (cluster_gain_stats.num_feasible_blocks == 0) {
if (!cluster_gain_stats.initial_search_for_feasible_blocks && cluster_gain_stats.feasible_blocks.size() == 0) {
add_cluster_molecule_candidates_by_attraction_group(cluster_gain_stats,
cluster_id,
cluster_legalizer,
attraction_groups);
}

/* Grab highest gain molecule */
// If this was a vector, this would just be a pop_back.
PackMoleculeId best_molecule = PackMoleculeId::INVALID();
if (cluster_gain_stats.num_feasible_blocks > 0) {
cluster_gain_stats.num_feasible_blocks--;
int index = cluster_gain_stats.num_feasible_blocks;
best_molecule = cluster_gain_stats.feasible_blocks[index];
VTR_ASSERT(!cluster_legalizer.is_mol_clustered(best_molecule));
// checking if there are feasible blocks being proposed
// checking if number of suggestion reached the limit
if (cluster_gain_stats.feasible_blocks.size() > 0 && cluster_gain_stats.num_search_for_feasible_blocks_occured < cluster_gain_stats.num_search_for_feasible_blocks_occurred_limit) {
best_molecule = cluster_gain_stats.feasible_blocks.pop().first;
if (best_molecule != PackMoleculeId::INVALID()) {
cluster_gain_stats.num_search_for_feasible_blocks_occured++;
VTR_ASSERT(!cluster_legalizer.is_mol_clustered(best_molecule));
}
}

// If we have no feasible blocks, or we have reached the limit of number of pops,
// then we need to clear the feasible blocks list and reset the number of pops.
// This ensures that we can continue searching for feasible blocks for the remaining
// steps (2.transitive, 3.high fanout, 4.attraction group).
if (cluster_gain_stats.feasible_blocks.size() == 0 ||
cluster_gain_stats.num_search_for_feasible_blocks_occured >= cluster_gain_stats.num_search_for_feasible_blocks_occurred_limit ||
cluster_gain_stats.feasible_blocks.delete_pending_set.size() == cluster_gain_stats.feasible_blocks.content_set.size()
){
cluster_gain_stats.feasible_blocks.clear();
cluster_gain_stats.num_search_for_feasible_blocks_occured = 0;
}

// If we are allowing unrelated clustering and no molecule has been found,
Expand Down Expand Up @@ -775,6 +788,9 @@ void GreedyCandidateSelector::add_cluster_molecule_candidates_by_connectivity_an
LegalizationClusterId legalization_cluster_id,
const ClusterLegalizer& cluster_legalizer,
AttractionInfo& attraction_groups) {

VTR_ASSERT(cluster_gain_stats.initial_search_for_feasible_blocks);
cluster_gain_stats.initial_search_for_feasible_blocks = false;
cluster_gain_stats.explore_transitive_fanout = true; /* If no legal molecules found, enable exploration of molecules two hops away */

for (AtomBlockId blk_id : cluster_gain_stats.marked_blocks) {
Expand Down Expand Up @@ -1001,45 +1017,17 @@ static void add_molecule_to_pb_stats_candidates(PackMoleculeId molecule_id,
}
}

for (int i = 0; i < cluster_gain_stats.num_feasible_blocks; i++) {
if (cluster_gain_stats.feasible_blocks[i] == molecule_id) {
return; // already in queue, do nothing
}
// if already in queue, do nothing
if (cluster_gain_stats.feasible_blocks.contains(molecule_id)) {
return;
}

if (cluster_gain_stats.num_feasible_blocks >= max_queue_size - 1) {
/* maximum size for array, remove smallest gain element and sort */
if (get_molecule_gain(molecule_id, cluster_gain_stats, cluster_att_grp, attraction_groups, num_molecule_failures, prepacker, atom_netlist, appack_ctx) > get_molecule_gain(cluster_gain_stats.feasible_blocks[0], cluster_gain_stats, cluster_att_grp, attraction_groups, num_molecule_failures, prepacker, atom_netlist, appack_ctx)) {
/* single loop insertion sort */
int j;
for (j = 0; j < cluster_gain_stats.num_feasible_blocks - 1; j++) {
if (get_molecule_gain(molecule_id, cluster_gain_stats, cluster_att_grp, attraction_groups, num_molecule_failures, prepacker, atom_netlist, appack_ctx) <= get_molecule_gain(cluster_gain_stats.feasible_blocks[j + 1], cluster_gain_stats, cluster_att_grp, attraction_groups, num_molecule_failures, prepacker, atom_netlist, appack_ctx)) {
cluster_gain_stats.feasible_blocks[j] = molecule_id;
break;
} else {
cluster_gain_stats.feasible_blocks[j] = cluster_gain_stats.feasible_blocks[j + 1];
}
}
if (j == cluster_gain_stats.num_feasible_blocks - 1) {
cluster_gain_stats.feasible_blocks[j] = molecule_id;
}
}
} else {
/* Expand array and single loop insertion sort */
int j;
for (j = cluster_gain_stats.num_feasible_blocks - 1; j >= 0; j--) {
if (get_molecule_gain(cluster_gain_stats.feasible_blocks[j], cluster_gain_stats, cluster_att_grp, attraction_groups, num_molecule_failures, prepacker, atom_netlist, appack_ctx) > get_molecule_gain(molecule_id, cluster_gain_stats, cluster_att_grp, attraction_groups, num_molecule_failures, prepacker, atom_netlist, appack_ctx)) {
cluster_gain_stats.feasible_blocks[j + 1] = cluster_gain_stats.feasible_blocks[j];
} else {
cluster_gain_stats.feasible_blocks[j + 1] = molecule_id;
break;
}
}
if (j < 0) {
cluster_gain_stats.feasible_blocks[0] = molecule_id;
}
cluster_gain_stats.num_feasible_blocks++;
for (std::pair<PackMoleculeId, float>& feasible_block : cluster_gain_stats.feasible_blocks.heap) {
VTR_ASSERT_DEBUG(get_molecule_gain(feasible_block.first, cluster_gain_stats, cluster_att_grp, attraction_groups, num_molecule_failures, prepacker, atom_netlist, appack_ctx) == feasible_block.second);
}

// Insert the molecule into the queue sorted by gain, and maintain the heap property
cluster_gain_stats.feasible_blocks.push(molecule_id, get_molecule_gain(molecule_id, cluster_gain_stats, cluster_att_grp, attraction_groups, num_molecule_failures, prepacker, atom_netlist, appack_ctx));
}

/*
Expand All @@ -1050,27 +1038,7 @@ static void add_molecule_to_pb_stats_candidates(PackMoleculeId molecule_id,
*/
static void remove_molecule_from_pb_stats_candidates(PackMoleculeId molecule_id,
ClusterGainStats& cluster_gain_stats) {
int molecule_index;
bool found_molecule = false;

//find the molecule index
for (int i = 0; i < cluster_gain_stats.num_feasible_blocks; i++) {
if (cluster_gain_stats.feasible_blocks[i] == molecule_id) {
found_molecule = true;
molecule_index = i;
}
}

//if it is not in the array, return
if (found_molecule == false) {
return;
}

//Otherwise, shift the molecules while removing the specified molecule
for (int j = molecule_index; j < cluster_gain_stats.num_feasible_blocks - 1; j++) {
cluster_gain_stats.feasible_blocks[j] = cluster_gain_stats.feasible_blocks[j + 1];
}
cluster_gain_stats.num_feasible_blocks--;
cluster_gain_stats.feasible_blocks.remove_at_pop_time(molecule_id);
}

/*
Expand Down
32 changes: 21 additions & 11 deletions vpr/src/pack/greedy_candidate_selector.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
#include "vtr_ndmatrix.h"
#include "vtr_vector.h"
#include "vtr_random.h"
#include "lazy_pop_unique_priority_queue.h"

// Forward declarations
class AtomNetlist;
Expand All @@ -33,6 +34,8 @@ struct t_model;
struct t_molecule_stats;
struct t_packer_opts;



/**
* @brief Stats on the gain of a cluster.
*
Expand Down Expand Up @@ -96,13 +99,6 @@ struct ClusterGainStats {
/// with the cluster.
AttractGroupId attraction_grp_id;

/// @brief Array of feasible blocks to select from [0..max_array_size-1]
///
/// Sorted in ascending gain order so that the last cluster_ctx.blocks is
/// the most desirable (this makes it easy to pop blocks off the list.
std::vector<PackMoleculeId> feasible_blocks;
int num_feasible_blocks;

/// @brief The flat placement location of this cluster.
///
/// This is some function of the positions of the molecules which have been
Expand All @@ -125,6 +121,20 @@ struct ClusterGainStats {
/// set when the stats are created based on the primitive pb type
/// of the seed.
bool is_memory = false;

/// @brief List of feasible block and its gain pairs.
/// The list is maintained in heap structure with the highest gain block
/// at the front.
LazyPopUniquePriorityQueue<PackMoleculeId, float> feasible_blocks;

/// @brief Indicator for the initial search for feasible blocks.
bool initial_search_for_feasible_blocks;

/// @brief Limit for the number of pop.
unsigned num_search_for_feasible_blocks_occurred_limit;

/// @brief Counter for the number of pop.
unsigned num_search_for_feasible_blocks_occured;
};

/**
Expand Down Expand Up @@ -441,7 +451,7 @@ class GreedyCandidateSelector {
// Cluster Candidate Selection
// ===================================================================== //

/*
/**
* @brief Add molecules with strong connectedness to the current cluster to
* the list of feasible blocks.
*/
Expand All @@ -468,7 +478,7 @@ class GreedyCandidateSelector {
LegalizationClusterId legalization_cluster_id,
const ClusterLegalizer& cluster_legalizer);

/*
/**
* @brief Add molecules based on transitive connections (eg. 2 hops away)
* with current cluster.
*/
Expand All @@ -478,7 +488,7 @@ class GreedyCandidateSelector {
const ClusterLegalizer& cluster_legalizer,
AttractionInfo& attraction_groups);

/*
/**
* @brief Add molecules based on weak connectedness (connected by high
* fanout nets) with current cluster.
*/
Expand All @@ -488,7 +498,7 @@ class GreedyCandidateSelector {
const ClusterLegalizer& cluster_legalizer,
AttractionInfo& attraction_groups);

/*
/**
* @brief If the current cluster being packed has an attraction group
* associated with it (i.e. there are atoms in it that belong to an
* attraction group), this routine adds molecules from the associated
Expand Down
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