[ClusterLegalizer] Moved Stat Counting Into Cluster Legalizer

Found that one of the pb_stats members is required for cluster
legalization; but was being calculated outside of the cluster legalizer.

Moved this in to allow the cluster legalizer to be used outside of the
clusterer.

Also found an issue where two clusters of the same type cannot be
constructed at the same time. Tried fixing it, but it produces different
results (different clusters). Will raise in a separate PR, left as a
fixme comment.

Author: AlexandreSinger

vpr/src/pack/cluster_legalizer.cpp

@@ -499,6 +499,7 @@ try_place_atom_block_rec(const t_pb_graph_node* pb_graph_node,
     const AtomContext& atom_ctx = g_vpr_ctx.atom();
     AtomContext& mutable_atom_ctx = g_vpr_ctx.mutable_atom();
 
+    VTR_ASSERT_SAFE(cb != nullptr);
     e_block_pack_status block_pack_status = e_block_pack_status::BLK_PASSED;
 
     /* Discover parent */
@@ -516,6 +517,7 @@ try_place_atom_block_rec(const t_pb_graph_node* pb_graph_node,
     }
 
     /* Create siblings if siblings are not allocated */
+    VTR_ASSERT(parent_pb != nullptr);
     if (parent_pb->child_pbs == nullptr) {
         VTR_ASSERT(parent_pb->name == nullptr);
         parent_pb->name = vtr::strdup(atom_ctx.nlist.block_name(blk_id).c_str());
@@ -533,8 +535,8 @@ try_place_atom_block_rec(const t_pb_graph_node* pb_graph_node,
             }
         }
     } else {
-       /* if this is not the first child of this parent, must match existing parent mode */
-       if (parent_pb->mode != pb_graph_node->pb_type->parent_mode->index) {
+        /* if this is not the first child of this parent, must match existing parent mode */
+        if (parent_pb->mode != pb_graph_node->pb_type->parent_mode->index) {
             return e_block_pack_status::BLK_FAILED_FEASIBLE;
         }
     }
@@ -548,6 +550,7 @@ try_place_atom_block_rec(const t_pb_graph_node* pb_graph_node,
     }
     VTR_ASSERT(i < mode->num_pb_type_children);
     t_pb* pb = &parent_pb->child_pbs[i][pb_graph_node->placement_index];
+    VTR_ASSERT_SAFE(pb != nullptr);
     *parent = pb; /* this pb is parent of it's child that called this function */
     VTR_ASSERT(pb->pb_graph_node == pb_graph_node);
     if (pb->pb_stats == nullptr) {
@@ -1364,6 +1367,15 @@ e_block_pack_status ClusterLegalizer::try_pack_molecule(t_pack_molecule* molecul
                     commit_primitive(cluster_placement_stats_ptr, primitives_list[i]);
 
                     atom_cluster_[atom_blk_id] = cluster_id;
+
+                    // Update the num child blocks in pb
+                    const t_pb* atom_pb = atom_ctx.lookup.atom_pb(atom_blk_id);
+                    VTR_ASSERT_SAFE(atom_pb != nullptr);
+                    t_pb* cur_pb = atom_pb->parent_pb;
+                    while (cur_pb != nullptr) {
+                        cur_pb->pb_stats->num_child_blocks_in_pb++;
+                        cur_pb = cur_pb->parent_pb;
+                    }
                 }
 
                 // Update the lookahead pins used.

vpr/src/pack/cluster_legalizer.h

@@ -416,6 +416,10 @@ class ClusterLegalizer {
 
     /// @brief Stats keeper for placement information during packing/clustering.
     /// TODO: This should be a vector.
+    /// FIXME: This keeps the stats for each cluster type. This is fine within
+    ///        the clusterer, however it yields a limitation where two clusters
+    ///        of the same type cannot be constructed at the same time. This
+    ///        should stored per cluster.
     t_cluster_placement_stats* cluster_placement_stats_ = nullptr;
 
     /// @brief The utilization of external input/output pins during packing

vpr/src/pack/cluster_util.cpp

@@ -973,7 +973,6 @@ void update_cluster_stats(const t_pack_molecule* molecule,
                 cb = cur_pb;
             }
             cur_pb->pb_stats->num_feasible_blocks = NOT_VALID;
-            cur_pb->pb_stats->num_child_blocks_in_pb++;
 
             if (atom_grp_id != AttractGroupId::INVALID()) {
                 /* TODO: Allow clusters to have more than one attraction group. */