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diff --git a/llvm/lib/Transforms/IPO/BarrierNoopPass.cpp b/llvm/lib/Transforms/IPO/BarrierNoopPass.cpp
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+++ b/llvm/lib/Transforms/IPO/BarrierNoopPass.cpp
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+//===- BarrierNoopPass.cpp - A barrier pass for the pass manager ----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// NOTE: DO NOT USE THIS IF AVOIDABLE
+//
+// This pass is a nonce pass intended to allow manipulation of the implicitly
+// nesting pass manager. For example, it can be used to cause a CGSCC pass
+// manager to be closed prior to running a new collection of function passes.
+//
+// FIXME: This is a huge HACK. This should be removed when the pass manager's
+// nesting is made explicit instead of implicit.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Pass.h"
+#include "llvm/Transforms/IPO.h"
+using namespace llvm;
+
+namespace {
+/// A nonce module pass used to place a barrier in a pass manager.
+///
+/// There is no mechanism for ending a CGSCC pass manager once one is started.
+/// This prevents extension points from having clear deterministic ordering
+/// when they are phrased as non-module passes.
+class BarrierNoop : public ModulePass {
+public:
+  static char ID; // Pass identification.
+
+  BarrierNoop() : ModulePass(ID) {
+    initializeBarrierNoopPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnModule(Module &M) override { return false; }
+};
+}
+
+ModulePass *llvm::createBarrierNoopPass() { return new BarrierNoop(); }
+
+char BarrierNoop::ID = 0;
+INITIALIZE_PASS(BarrierNoop, "barrier", "A No-Op Barrier Pass",
+                false, false)