[Clustering] Independent Clustering Verification

Created a method that would independently verify the clustering in the
VPR flow. If a clustering passes this verification, it is assumed that
it can be used in placement and routing without issue.

By design, this method does not use any global variables (everything
needs to be passed in) and it recomputes everything that it does not
assume. This allows it to be independent of the packing flow, so this
method can also be used in the AP flow.

Author: AlexandreSinger

vpr/src/analytical_place/full_legalizer.cpp

@@ -24,6 +24,7 @@
 #include "pack.h"
 #include "physical_types.h"
 #include "place_constraints.h"
+#include "verify_clustering.h"
 #include "vpr_api.h"
 #include "vpr_context.h"
 #include "vpr_error.h"
@@ -389,6 +390,18 @@ void FullLegalizer::legalize(const PartialPlacement& p_placement) {
 
     // Pack the atoms into clusters based on the partial placement.
     create_clusters(p_placement);
+    // Verify that the clustering created by the full legalizer is valid.
+    unsigned num_clustering_errors = verify_clustering(g_vpr_ctx);
+    if (num_clustering_errors == 0) {
+        VTR_LOG("Completed clustering consistency check successfully.\n");
+    } else {
+        VPR_ERROR(VPR_ERROR_AP,
+                  "Completed placement consistency check, %u errors found.\n"
+                  "Aborting program.\n",
+                  num_clustering_errors);
+    }
+    // Get the clustering from the global context.
+    // TODO: Eventually should be returned from the create_clusters method.
     const ClusteredNetlist& clb_nlist = g_vpr_ctx.clustering().clb_nlist;
 
     // Place the clusters based on where the atoms want to be placed.

vpr/src/base/vpr_api.cpp

@@ -70,6 +70,7 @@
 #include "place_util.h"
 #include "timing_fail_error.h"
 #include "analytical_placement_flow.h"
+#include "verify_clustering.h"
 
 #include "vpr_constraints_writer.h"
 
@@ -644,6 +645,22 @@ bool vpr_pack_flow(t_vpr_setup& vpr_setup, const t_arch& arch) {
         /* Sanity check the resulting netlist */
         check_netlist(packer_opts.pack_verbosity);
 
+        // Independently verify the clusterings to ensure the clustering can be
+        // used for the rest of the VPR flow.
+        // NOTE: This is done here since it must be done after vpr_load_packing
+        //       and load_cluster_constraints.
+        // TODO: If load_cluster_constraints was in vpr_load_packing, this could
+        //       also be in vpr_load_packing which would make more sense.
+        unsigned num_errors = verify_clustering(g_vpr_ctx);
+        if (num_errors == 0) {
+            VTR_LOG("Completed clustering consistency check successfully.\n");
+        } else {
+            VPR_ERROR(VPR_ERROR_PACK,
+                      "%u errors found while performing clustering consistency "
+                      "check. Aborting program.\n",
+                      num_errors);
+        }
+
         /* Output the netlist stats to console and optionally to file. */
         writeClusteredNetlistStats(vpr_setup.FileNameOpts.write_block_usage);