From 52822ded702c334318d12be01b83ed16d0697401 Mon Sep 17 00:00:00 2001
From: Nate Chandler <nate_chandler@apple.com>
Date: Wed, 8 Oct 2025 17:04:19 -0700
Subject: [PATCH] [DeadObjectElim] Bail on invalid access path.

rdar://162237650
---
 .../Transforms/DeadObjectElimination.cpp        |  2 ++
 .../SILOptimizer/rdar162237650.swift            | 17 +++++++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 validation-test/SILOptimizer/rdar162237650.swift

diff --git a/lib/SILOptimizer/Transforms/DeadObjectElimination.cpp b/lib/SILOptimizer/Transforms/DeadObjectElimination.cpp
index b96f862b23b63..923c19dad59c7 100644
--- a/lib/SILOptimizer/Transforms/DeadObjectElimination.cpp
+++ b/lib/SILOptimizer/Transforms/DeadObjectElimination.cpp
@@ -351,6 +351,8 @@ static bool onlyStoresToTailObjects(BuiltinInst *destroyArray,
 
   // Check if the destroyArray destroys the tail elements of allocRef.
   auto destroyPath = AccessPath::compute(destroyArray->getArguments()[1]);
+  if (!destroyPath.isValid())
+    return false;
   AccessStorage storage = destroyPath.getStorage();
   if (auto *beginDealloc = dyn_cast<BeginDeallocRefInst>(storage.getRoot())) {
     destroyPath = AccessPath(
diff --git a/validation-test/SILOptimizer/rdar162237650.swift b/validation-test/SILOptimizer/rdar162237650.swift
new file mode 100644
index 0000000000000..f15fab47c20ad
--- /dev/null
+++ b/validation-test/SILOptimizer/rdar162237650.swift
@@ -0,0 +1,17 @@
+// RUN: %target-swift-frontend -c -O %s -target %target-swift-6.0-abi-triple
+
+// REQUIRES: synchronization
+
+import Synchronization
+
+class Locked<T> {
+  let mutex: Mutex<T>
+
+  init(_ rawValue: T) {
+    mutex = Mutex(rawValue)
+  }
+}
+
+class Foo {}
+
+_ = Locked(Foo())