From 96f221d7e23bf7f2533e002b9156298e4745155f Mon Sep 17 00:00:00 2001
From: Thomas Lively <tlively@google.com>
Date: Thu, 1 Oct 2026 16:04:32 -0700
Subject: [PATCH] Clear loopTops in CFGWalker

CFGWalker clears all its local state when visiting a function, but it previously did not clear loopTops. If CFGWalker were to be used in a non-function-parallel pass, this would lead to dangling BasicBlock pointers in loopTops. There does not happen to be such a use of CFGWalker today, but it is still worth fixing.
---
 src/cfg/cfg-traversal.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/cfg/cfg-traversal.h b/src/cfg/cfg-traversal.h
index 10abd9e4f0a..6cc758e6e2c 100644
--- a/src/cfg/cfg-traversal.h
+++ b/src/cfg/cfg-traversal.h
@@ -579,6 +579,7 @@ struct CFGWalker : public PostWalker<SubType, VisitorType> {
 
   void doWalkFunction(Function* func) {
     basicBlocks.clear();
+    loopTops.clear();
     debugIds.clear();
     exit = nullptr;
     hasSyntheticExit = false;