Merge pull request #2816 from AlexandreSinger/feature-greedy-clustere…

…r-class

[Packer] Created GreedyClusterer Class

vpr/src/analytical_place/full_legalizer.cpp

@@ -17,7 +17,6 @@
 #include "ShowSetup.h"
 #include "ap_netlist_fwd.h"
 #include "check_netlist.h"
-#include "cluster.h"
 #include "cluster_legalizer.h"
 #include "cluster_util.h"
 #include "clustered_netlist.h"

vpr/src/base/vpr_api.cpp

@@ -64,7 +64,6 @@
 #include "check_route.h"
 #include "constant_nets.h"
 #include "atom_netlist_utils.h"
-#include "cluster.h"
 #include "output_clustering.h"
 #include "vpr_constraints_reader.h"
 #include "place_constraints.h"

vpr/src/pack/cluster_util.cpp

@@ -1879,6 +1879,32 @@ void print_pb_type_count_recurr(t_pb_type* pb_type, size_t max_name_chars, size_
     }
 }
 
+void print_pb_type_count(const ClusteredNetlist& clb_nlist) {
+    auto& device_ctx = g_vpr_ctx.device();
+
+    std::map<t_pb_type*, int> pb_type_count;
+
+    size_t max_depth = 0;
+    for (ClusterBlockId blk : clb_nlist.blocks()) {
+        size_t pb_max_depth = update_pb_type_count(clb_nlist.block_pb(blk), pb_type_count, 0);
+
+        max_depth = std::max(max_depth, pb_max_depth);
+    }
+
+    size_t max_pb_type_name_chars = 0;
+    for (auto& pb_type : pb_type_count) {
+        max_pb_type_name_chars = std::max(max_pb_type_name_chars, strlen(pb_type.first->name));
+    }
+
+    VTR_LOG("\nPb types usage...\n");
+    for (const auto& logical_block_type : device_ctx.logical_block_types) {
+        if (!logical_block_type.pb_type) continue;
+
+        print_pb_type_count_recurr(logical_block_type.pb_type, max_pb_type_name_chars + max_depth, 0, pb_type_count);
+    }
+    VTR_LOG("\n");
+}
+
 t_logical_block_type_ptr identify_logic_block_type(std::map<const t_model*, std::vector<t_logical_block_type_ptr>>& primitive_candidate_block_types) {
     std::string lut_name = ".names";
 

vpr/src/pack/cluster_util.h

@@ -481,6 +481,11 @@ void update_le_count(const t_pb* pb, const t_logical_block_type_ptr logic_block_
 
 void print_pb_type_count_recurr(t_pb_type* type, size_t max_name_chars, size_t curr_depth, std::map<t_pb_type*, int>& pb_type_count);
 
+/**
+ * Print the total number of used physical blocks for each pb type in the architecture
+ */
+void print_pb_type_count(const ClusteredNetlist& clb_nlist);
+
 /*
  * @brief This function identifies the logic block type which is defined by the
  *        block type which has a lut primitive.

vpr/src/pack/greedy_clusterer.h

@@ -0,0 +1,163 @@
+/**
+ * @file
+ * @author  Alex Singer
+ * @date    November 2024
+ * @brief   The declarations of the Greedy Clusterer class which is used to
+ *          encapsulate the process of greedy clustering.
+ */
+
+#pragma once
+
+#include <map>
+#include <unordered_set>
+#include "physical_types.h"
+
+// Forward declarations
+class AtomNetId;
+class AtomNetlist;
+class AttractionInfo;
+class ClusterLegalizer;
+class Prepacker;
+struct t_analysis_opts;
+struct t_clustering_data;
+struct t_pack_high_fanout_thresholds;
+struct t_packer_opts;
+
+/**
+ * @brief A clusterer that generates clusters by greedily choosing the clusters
+ *        which appear to have the best gain for a given neighbor.
+ *
+ * This clusterer generates one cluster at a time by finding candidate molecules
+ * and selecting the molecule with the highest gain.
+ *
+ * The clusterer takes an Atom Netlist which has be pre-packed into pack
+ * patterns (e.g. carry chains) as input and produces a set of legal clusters
+ * of these pack molecules as output. Legality here means that it was able to
+ * find a valid intra-lb route for the inputs of the clusters, through the
+ * internal molecules, and to the outputs of the clusters.
+ */
+class GreedyClusterer {
+public:
+    /**
+     * @brief Constructor of the Greedy Clusterer class.
+     *
+     * The clusterer may be invoked many times during the packing flow. This
+     * constructor will pre-compute information before clustering which can
+     * improve the performance of the clusterer.
+     *
+     *  @param packer_opts
+     *              Options passed by the user to configure the packing and
+     *              clustering algorithms.
+     *  @param analysis_opts
+     *              Options passed by the user to configure timing analysis in
+     *              the clusterer.
+     *  @param atom_netlist
+     *              The atom netlist to cluster over.
+     *  @param arch
+     *              The architecture to cluster over.
+     *  @param high_fanout_thresholds
+     *              The thresholds for what to consider as a high-fanout net
+     *              for each logical block type. The clusterer will not consider
+     *              nets with fanout higher than this to be important in
+     *              candidate block selection (gain computation).
+     *              A reason for it being per block type is that some blocks,
+     *              like RAMs, have weak gains to other RAM primitives due to
+     *              fairly high fanout address nets, so a higher fanout
+     *              threshold for them is useful in generating a more dense
+     *              packing.
+     *  @param is_clock
+     *              The set of clock nets in the Atom Netlist.
+     *  @param is_global
+     *              The set of global nets in the Atom Netlist. These will be
+     *              routed on special dedicated networks, and hence are less
+     *              relavent to locality / attraction.
+     */
+    GreedyClusterer(const t_packer_opts& packer_opts,
+                    const t_analysis_opts& analysis_opts,
+                    const AtomNetlist& atom_netlist,
+                    const t_arch* arch,
+                    const t_pack_high_fanout_thresholds& high_fanout_thresholds,
+                    const std::unordered_set<AtomNetId>& is_clock,
+                    const std::unordered_set<AtomNetId>& is_global);
+
+    /**
+     * @brief Performs clustering on the pack molecules formed by the prepacker.
+     *
+     * The clustering is contained within the Cluster Legalizer.
+     *
+     *  @param cluster_legalizer
+     *              The cluster legalizer which is used to create clusters and
+     *              grow clusters by adding molecules to a cluster.
+     *  @param prepacker
+     *              The prepacker object which contains the pack molecules that
+     *              are atoms which are pre-packed before the main clustering
+     *              (due to pack patterns, e.g. carry chains).
+     *  @param allow_unrelated_clustering
+     *              Allows primitives which have no attraction to the given
+     *              cluster to be packed into it. This can lead to a denser
+     *              packing, but tends to be bad for wirelength and timing.
+     *  @param balance_block_type_utilization
+     *              When true, tries to create clusters that balance the logical
+     *              block type utilization. This is useful when some primitives
+     *              have multiple logical block types to which they can cluster,
+     *              e.g. multiple sizes of physical RAMs exist on the chip.
+     *  @param attraction_groups
+     *              Information on the attraction groups used during the
+     *              clustering process. These are groups of primitives that have
+     *              extra attraction to each other; currently they are used to
+     *              guide the clusterer when it must cluster some parts of a
+     *              design densely due to user placement/floorplanning
+     *              constraints. They are created if some floorplan regions are
+     *              overfilled after a clustering attempt.
+     *
+     *  @return num_used_type_instances
+     *              The number of used logical blocks of each type by the
+     *              clustering. This information may be useful when detecting
+     *              if the clustering can fit on the device.
+     */
+    std::map<t_logical_block_type_ptr, size_t>
+    do_clustering(ClusterLegalizer& cluster_legalizer,
+                  Prepacker& prepacker,
+                  bool allow_unrelated_clustering,
+                  bool balance_block_type_utilization,
+                  AttractionInfo& attraction_groups);
+
+private:
+    /*
+     * When attraction groups are created, the purpose is to pack more densely by adding more molecules
+     * from the cluster's attraction group to the cluster. In a normal flow, (when attraction groups are
+     * not on), the cluster keeps being packed until the get_molecule routines return either a repeated
+     * molecule or a nullptr. When attraction groups are on, we want to keep exploring molecules for the
+     * cluster until a nullptr is returned. So, the number of repeated molecules is changed from 1 to 500,
+     * effectively making the clusterer pack a cluster until a nullptr is returned.
+     */
+    static constexpr int attraction_groups_max_repeated_molecules_ = 500;
+
+    /// @brief The packer options used to configure the clusterer.
+    const t_packer_opts& packer_opts_;
+
+    /// @brief The analysis options used to configure timing analysis within the
+    ///        clusterer.
+    const t_analysis_opts& analysis_opts_;
+
+    /// @brief The atom netlist to cluster over.
+    const AtomNetlist& atom_netlist_;
+
+    /// @brief The device architecture to cluster onto.
+    const t_arch* arch_ = nullptr;
+
+    /// @brief The high-fanout thresholds per logical block type. Used to ignore
+    ///        certain nets when calculating the gain for the next candidate
+    ///        molecule to cluster.
+    const t_pack_high_fanout_thresholds& high_fanout_thresholds_;
+
+    /// @brief A set of atom nets which are considered as clocks.
+    const std::unordered_set<AtomNetId>& is_clock_;
+
+    /// @brief A set of atom nets which are considered as global nets.
+    const std::unordered_set<AtomNetId>& is_global_;
+
+    /// @brief Pre-computed logical block types for each model in the architecture.
+    std::map<const t_model*, std::vector<t_logical_block_type_ptr>> primitive_candidate_block_types_;
+};
+

vpr/src/pack/pack.cpp

@@ -1,10 +1,11 @@
 #include <unordered_set>
 
 #include "SetupGrid.h"
-#include "cluster.h"
 #include "cluster_legalizer.h"
 #include "cluster_util.h"
+#include "constraints_report.h"
 #include "globals.h"
+#include "greedy_clusterer.h"
 #include "pack.h"
 #include "prepack.h"
 #include "vpr_context.h"
@@ -29,7 +30,6 @@ bool try_pack(t_packer_opts* packer_opts,
     const DeviceContext& device_ctx = g_vpr_ctx.device();
 
     std::unordered_set<AtomNetId> is_clock, is_global;
-    t_clustering_data clustering_data;
     VTR_LOG("Begin packing '%s'.\n", packer_opts->circuit_file_name.c_str());
 
     is_clock = alloc_and_load_is_clock();
@@ -91,7 +91,6 @@ bool try_pack(t_packer_opts* packer_opts,
     }
 
     int pack_iteration = 1;
-    bool floorplan_regions_overfull = false;
 
     // Initialize the cluster legalizer.
     ClusterLegalizer cluster_legalizer(atom_ctx.nlist,
@@ -110,27 +109,25 @@ bool try_pack(t_packer_opts* packer_opts,
     VTR_LOG("Packing with pin utilization targets: %s\n", cluster_legalizer.get_target_external_pin_util().to_string().c_str());
     VTR_LOG("Packing with high fanout thresholds: %s\n", high_fanout_thresholds.to_string().c_str());
 
-    while (true) {
-        free_clustering_data(*packer_opts, clustering_data);
-
+    // Initialize the greedy clusterer.
+    GreedyClusterer clusterer(*packer_opts,
+                              *analysis_opts,
+                              atom_ctx.nlist,
+                              arch,
+                              high_fanout_thresholds,
+                              is_clock,
+                              is_global);
 
+    while (true) {
         //Cluster the netlist
         //  num_used_type_instances: A map used to save the number of used
         //                           instances from each logical block type.
         std::map<t_logical_block_type_ptr, size_t> num_used_type_instances;
-        num_used_type_instances = do_clustering(*packer_opts,
-                                                *analysis_opts,
-                                                arch,
-                                                prepacker,
-                                                cluster_legalizer,
-                                                is_clock,
-                                                is_global,
-                                                allow_unrelated_clustering,
-                                                balance_block_type_util,
-                                                attraction_groups,
-                                                floorplan_regions_overfull,
-                                                high_fanout_thresholds,
-                                                clustering_data);
+        num_used_type_instances = clusterer.do_clustering(cluster_legalizer,
+                                                          prepacker,
+                                                          allow_unrelated_clustering,
+                                                          balance_block_type_util,
+                                                          attraction_groups);
 
         //Try to size/find a device
         bool fits_on_device = try_size_device_grid(*arch, num_used_type_instances, packer_opts->target_device_utilization, packer_opts->device_layout);
@@ -139,6 +136,7 @@ bool try_pack(t_packer_opts* packer_opts,
          * is not dense enough and there are floorplan constraints, it is presumed that the constraints are the cause
          * of the floorplan not fitting, so attraction groups are turned on for later iterations.
          */
+        bool floorplan_regions_overfull = floorplan_constraints_regions_overfull(cluster_legalizer);
         bool floorplan_not_fitting = (floorplan_regions_overfull || g_vpr_ctx.floorplanning().constraints.get_num_partitions() > 0);
 
         if (fits_on_device && !floorplan_regions_overfull) {
@@ -261,9 +259,6 @@ bool try_pack(t_packer_opts* packer_opts,
     //check clustering and output it
     check_and_output_clustering(cluster_legalizer, *packer_opts, is_clock, arch);
 
-    // Free Data Structures
-    free_clustering_data(*packer_opts, clustering_data);
-
     VTR_LOG("\n");
     VTR_LOG("Netlist conversion complete.\n");
     VTR_LOG("\n");