LLVM  6.0.0svn
BarrierNoopPass.cpp
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1 //===- BarrierNoopPass.cpp - A barrier pass for the pass manager ----------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // NOTE: DO NOT USE THIS IF AVOIDABLE
11 //
12 // This pass is a nonce pass intended to allow manipulation of the implicitly
13 // nesting pass manager. For example, it can be used to cause a CGSCC pass
14 // manager to be closed prior to running a new collection of function passes.
15 //
16 // FIXME: This is a huge HACK. This should be removed when the pass manager's
17 // nesting is made explicit instead of implicit.
18 //
19 //===----------------------------------------------------------------------===//
20 
21 #include "llvm/Pass.h"
22 #include "llvm/Transforms/IPO.h"
23 using namespace llvm;
24 
25 namespace {
26 /// \brief A nonce module pass used to place a barrier in a pass manager.
27 ///
28 /// There is no mechanism for ending a CGSCC pass manager once one is started.
29 /// This prevents extension points from having clear deterministic ordering
30 /// when they are phrased as non-module passes.
31 class BarrierNoop : public ModulePass {
32 public:
33  static char ID; // Pass identification.
34 
35  BarrierNoop() : ModulePass(ID) {
37  }
38 
39  bool runOnModule(Module &M) override { return false; }
40 };
41 }
42 
43 ModulePass *llvm::createBarrierNoopPass() { return new BarrierNoop(); }
44 
45 char BarrierNoop::ID = 0;
46 INITIALIZE_PASS(BarrierNoop, "barrier", "A No-Op Barrier Pass",
47  false, false)
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:63
ModulePass * createBarrierNoopPass()
createBarrierNoopPass - This pass is purely a module pass barrier in a pass manager.
#define INITIALIZE_PASS(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:34
ModulePass class - This class is used to implement unstructured interprocedural optimizations and ana...
Definition: Pass.h:235
void initializeBarrierNoopPass(PassRegistry &)