//===- BarrierNoopPass.cpp - A barrier pass for the pass manager ----------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // 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 { /// \brief 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) |