| 1 | //===- BarrierNoopPass.cpp - A barrier pass for the pass manager ----------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // |
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| 9 | // NOTE: DO NOT USE THIS IF AVOIDABLE |
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| 10 | // |
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| 11 | // This pass is a nonce pass intended to allow manipulation of the implicitly |
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| 12 | // nesting pass manager. For example, it can be used to cause a CGSCC pass |
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| 13 | // manager to be closed prior to running a new collection of function passes. |
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| 14 | // |
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| 15 | // FIXME: This is a huge HACK. This should be removed when the pass manager's |
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| 16 | // nesting is made explicit instead of implicit. |
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| 17 | // |
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| 18 | //===----------------------------------------------------------------------===// |
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| 19 | |
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| 20 | #include "llvm/InitializePasses.h" |
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| 21 | #include "llvm/Pass.h" |
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| 22 | #include "llvm/Transforms/IPO.h" |
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| 23 | using namespace llvm; |
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| 24 | |
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| 25 | namespace { |
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| 26 | /// A nonce module pass used to place a barrier in a pass manager. |
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| 27 | /// |
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| 28 | /// There is no mechanism for ending a CGSCC pass manager once one is started. |
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| 29 | /// This prevents extension points from having clear deterministic ordering |
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| 30 | /// when they are phrased as non-module passes. |
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| 31 | class BarrierNoop : public ModulePass { |
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| 32 | public: |
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| 33 | static char ID; // Pass identification. |
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| 34 | |
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| 35 | BarrierNoop() : ModulePass(ID) { |
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| 36 | initializeBarrierNoopPass(*PassRegistry::getPassRegistry()); |
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| 37 | } |
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| 38 | |
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| 39 | bool runOnModule(Module &M) override { return false; } |
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| 40 | }; |
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| 41 | } |
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| 42 | |
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| 43 | ModulePass *llvm::createBarrierNoopPass() { return new BarrierNoop(); } |
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| 44 | |
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| 45 | char BarrierNoop::ID = 0; |
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| 46 | INITIALIZE_PASS(BarrierNoop, "barrier" , "A No-Op Barrier Pass" , |
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| 47 | false, false) |
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| 48 | |
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