BarrierNoopPass.cpp revision 360784
1192661Ssam//===- BarrierNoopPass.cpp - A barrier pass for the pass manager ----------===// 2192661Ssam// 3192661Ssam// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4192661Ssam// See https://llvm.org/LICENSE.txt for license information. 5192661Ssam// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6192661Ssam// 7192661Ssam//===----------------------------------------------------------------------===// 8192661Ssam// 9192661Ssam// NOTE: DO NOT USE THIS IF AVOIDABLE 10192661Ssam// 11192661Ssam// This pass is a nonce pass intended to allow manipulation of the implicitly 12192661Ssam// nesting pass manager. For example, it can be used to cause a CGSCC pass 13192661Ssam// manager to be closed prior to running a new collection of function passes. 14192661Ssam// 15192661Ssam// FIXME: This is a huge HACK. This should be removed when the pass manager's 16192661Ssam// nesting is made explicit instead of implicit. 17192661Ssam// 18192661Ssam//===----------------------------------------------------------------------===// 19192661Ssam 20192661Ssam#include "llvm/InitializePasses.h" 21192661Ssam#include "llvm/Pass.h" 22192661Ssam#include "llvm/Transforms/IPO.h" 23192661Ssamusing namespace llvm; 24192661Ssam 25192661Ssamnamespace { 26192661Ssam/// A nonce module pass used to place a barrier in a pass manager. 27192661Ssam/// 28192661Ssam/// There is no mechanism for ending a CGSCC pass manager once one is started. 29192661Ssam/// This prevents extension points from having clear deterministic ordering 30192661Ssam/// when they are phrased as non-module passes. 31192661Ssamclass BarrierNoop : public ModulePass { 32192661Ssampublic: 33192661Ssam static char ID; // Pass identification. 34192661Ssam 35192661Ssam BarrierNoop() : ModulePass(ID) { 36192661Ssam initializeBarrierNoopPass(*PassRegistry::getPassRegistry()); 37192661Ssam } 38192661Ssam 39192661Ssam bool runOnModule(Module &M) override { return false; } 40192661Ssam}; 41192661Ssam} 42192661Ssam 43192661SsamModulePass *llvm::createBarrierNoopPass() { return new BarrierNoop(); } 44192661Ssam 45192661Ssamchar BarrierNoop::ID = 0; 46192661SsamINITIALIZE_PASS(BarrierNoop, "barrier", "A No-Op Barrier Pass", 47192661Ssam false, false) 48192661Ssam