[FIRRTL] Remove unused allUnder utility

Remove an unused utility function.  This was previously used by
GrandCentral, but this is no longer load bearing.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@sifive.com>

include/circt/Dialect/FIRRTL/FIRRTLInstanceGraph.h

@@ -50,8 +50,6 @@ class InstanceGraph : public igraph::InstanceGraph {
   InstanceGraphNode *topLevelNode;
 };
 
-bool allUnder(ArrayRef<InstanceRecord *> nodes, InstanceGraphNode *top);
-
 } // namespace firrtl
 } // namespace circt
 

lib/Dialect/FIRRTL/FIRRTLInstanceGraph.cpp

@@ -24,36 +24,3 @@ InstanceGraph::InstanceGraph(Operation *operation)
     : igraph::InstanceGraph(findCircuitOp(operation)) {
   topLevelNode = lookup(cast<CircuitOp>(getParent()).getNameAttr());
 }
-
-bool circt::firrtl::allUnder(ArrayRef<InstanceRecord *> nodes,
-                             InstanceGraphNode *top) {
-  DenseSet<InstanceGraphNode *> seen;
-  SmallVector<InstanceGraphNode *> worklist;
-  worklist.reserve(nodes.size());
-  seen.reserve(nodes.size());
-  seen.insert(top);
-  for (auto *n : nodes) {
-    auto *mod = n->getParent();
-    if (seen.insert(mod).second)
-      worklist.push_back(mod);
-  }
-
-  while (!worklist.empty()) {
-    auto *node = worklist.back();
-    worklist.pop_back();
-
-    assert(node != top);
-
-    // If reach top-level node we're not covered by 'top', return.
-    if (node->noUses())
-      return false;
-
-    // Otherwise, walk upwards.
-    for (auto *use : node->uses()) {
-      auto *mod = use->getParent();
-      if (seen.insert(mod).second)
-        worklist.push_back(mod);
-    }
-  }
-  return true;
-}