Don't use ports when edges attach to clusters.

Author: ehein6

mlir/lib/Transforms/ViewOpGraph.cpp

@@ -247,12 +247,12 @@ class PrintOpPass : public impl::ViewOpGraphBase<PrintOpPass> {
 
     edges.push_back(strFromOs([&](raw_ostream &os) {
       os << "v" << n1.id;
-      if (!port.empty())
+      if (!port.empty() && !n1.clusterId)
         // Attach edge to south compass point of the result
         os << ":res" << port << ":s";
       os << " -> ";
       os << "v" << n2.id;
-      if (!port.empty())
+      if (!port.empty() && !n2.clusterId)
         // Attach edge to north compass point of the operand
         os << ":arg" << port << ":n";
       emitAttrList(os, attrs);

mlir/test/Transforms/print-op-graph-cycles.mlir

@@ -33,7 +33,7 @@
 //       DFG:   v9:res_0:s -> v9:arg_0:n[style = solid];
 //       DFG:   v15:res_2:s -> v9:arg_2:n[style = solid];
 //       DFG:   v9:res_0:s -> v14:arg_0:n[style = solid];
-//       DFG:   v11:res_1:s -> v14:arg_1:n[ltail = cluster_10, style = solid];
+//       DFG:   v11 -> v14:arg_1:n[ltail = cluster_10, style = solid];
 //       DFG:   v15:res_2:s -> v14:arg_2:n[style = solid];
 //       DFG:   v16:res_3:s -> v14:arg_3:n[style = solid];
 //       DFG:   v9:res_0:s -> v15:arg_0:n[style = solid];

mlir/test/Transforms/print-op-graph.mlir

@@ -20,8 +20,8 @@
 //       DFG:         v[[TEST_RET:.*]] [{{.*}}label = "{{.*}}test.return
 //       DFG:   v[[ARG0]]:res_arg0:s -> v[[TEST_BR]]:arg_arg0:n
 //       DFG:   v[[CONST10]]:res_c10_i32:s -> v[[TEST_BR]]
-//       DFG:   v[[ANCHOR]]:res_1_0:s -> v[[TEST_RET]]:arg_1_0:n[ltail = [[CLUSTER_MERGE_BLOCKS]], style = solid];
-//       DFG:   v[[ANCHOR]]:res_1_1:s -> v[[TEST_RET]]:arg_1_1:n[ltail = [[CLUSTER_MERGE_BLOCKS]], style = solid];
+//       DFG:   v[[ANCHOR]] -> v[[TEST_RET]]:arg_1_0:n[ltail = [[CLUSTER_MERGE_BLOCKS]], style = solid];
+//       DFG:   v[[ANCHOR]] -> v[[TEST_RET]]:arg_1_1:n[ltail = [[CLUSTER_MERGE_BLOCKS]], style = solid];
 
 // CFG-LABEL: digraph G {
 //       CFG:   subgraph {{.*}} {