From 4695876d24db133845328f71b0bf2d7e5a6199e4 Mon Sep 17 00:00:00 2001
From: Schuyler Eldridge <schuyler.eldridge@sifive.com>
Date: Mon, 26 Feb 2024 16:44:53 -0500
Subject: [PATCH] [Support] Make isAncestor filterable

Add a function argument to the InstanceGraph::isAncestor member function
to allow this to skip over certain instances.  This is intended to be used
for things like checking if a module is an ancestor of another without
looking through binds.

This is currently not load bearing.

This may help with checks like #5530.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@sifive.com>
---
 include/circt/Support/InstanceGraph.h | 5 ++++-
 lib/Support/InstanceGraph.cpp         | 7 +++++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/circt/Support/InstanceGraph.h b/include/circt/Support/InstanceGraph.h
index 4b6dcf210d..40a8196e8f 100644
--- a/include/circt/Support/InstanceGraph.h
+++ b/include/circt/Support/InstanceGraph.h
@@ -210,7 +210,10 @@ public:
   InstanceGraphNode *operator[](ModuleOpInterface op) { return lookup(op); }
 
   /// Check if child is instantiated by a parent.
-  bool isAncestor(ModuleOpInterface child, ModuleOpInterface parent);
+  bool isAncestor(
+      ModuleOpInterface child, ModuleOpInterface parent,
+      llvm::function_ref<bool(InstanceRecord *)> skipInstance =
+          [](InstanceRecord *_) { return false; });
 
   /// Get the node corresponding to the top-level module of a circuit.
   virtual InstanceGraphNode *getTopLevelNode() { return nullptr; }
diff --git a/lib/Support/InstanceGraph.cpp b/lib/Support/InstanceGraph.cpp
index e05c81b11d..cac7dc5786 100644
--- a/lib/Support/InstanceGraph.cpp
+++ b/lib/Support/InstanceGraph.cpp
@@ -136,8 +136,9 @@ void InstanceGraph::replaceInstance(InstanceOpInterface inst,
   }
 }
 
-bool InstanceGraph::isAncestor(ModuleOpInterface child,
-                               ModuleOpInterface parent) {
+bool InstanceGraph::isAncestor(
+    ModuleOpInterface child, ModuleOpInterface parent,
+    llvm::function_ref<bool(InstanceRecord *)> skipInstance) {
   DenseSet<InstanceGraphNode *> seen;
   SmallVector<InstanceGraphNode *> worklist;
   auto *cn = lookup(child);
@@ -149,6 +150,8 @@ bool InstanceGraph::isAncestor(ModuleOpInterface child,
     if (node->getModule() == parent)
       return true;
     for (auto *use : node->uses()) {
+      if (skipInstance(use))
+        continue;
       auto *mod = use->getParent();
       if (!seen.count(mod)) {
         seen.insert(mod);