1 //===- llvm/Pass.h - Base class for Passes ----------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines a base class that indicates that a specified class is a
11 // transformation pass implementation.
13 // Passes are designed this way so that it is possible to run passes in a cache
14 // and organizationally optimal order without having to specify it at the front
15 // end. This allows arbitrary passes to be strung together and have them
16 // executed as effeciently as possible.
18 // Passes should extend one of the classes below, depending on the guarantees
19 // that it can make about what will be modified as it is run. For example, most
20 // global optimizations should derive from FunctionPass, because they do not add
21 // or delete functions, they operate on the internals of the function.
23 // Note that this file #includes PassSupport.h and PassAnalysisSupport.h (at the
24 // bottom), so the APIs exposed by these files are also automatically available
25 // to all users of this file.
27 //===----------------------------------------------------------------------===//
32 #include "llvm/Support/Streams.h"
49 template<class Trait> class PassManagerT;
50 class BasicBlockPassManager;
51 class FunctionPassManagerT;
52 class ModulePassManager;
54 class AnalysisResolver;
57 // AnalysisID - Use the PassInfo to identify a pass...
58 typedef const PassInfo* AnalysisID;
60 //===----------------------------------------------------------------------===//
61 /// Pass interface - Implemented by all 'passes'. Subclass this if you are an
62 /// interprocedural optimization or you do not fit into any of the more
63 /// constrained passes described below.
66 AnalysisResolver *Resolver; // Used to resolve analysis
67 const PassInfo *PassInfoCache;
69 // AnalysisImpls - This keeps track of which passes implement the interfaces
70 // that are required by the current pass (to implement getAnalysis()).
72 std::vector<std::pair<const PassInfo*, Pass*> > AnalysisImpls;
74 void operator=(const Pass&); // DO NOT IMPLEMENT
75 Pass(const Pass &); // DO NOT IMPLEMENT
77 Pass() : Resolver(0), PassInfoCache(0) {}
78 virtual ~Pass() {} // Destructor is virtual so we can be subclassed
80 /// getPassName - Return a nice clean name for a pass. This usually
81 /// implemented in terms of the name that is registered by one of the
82 /// Registration templates, but can be overloaded directly, and if nothing
83 /// else is available, C++ RTTI will be consulted to get a SOMEWHAT
84 /// intelligible name for the pass.
86 virtual const char *getPassName() const;
88 /// getPassInfo - Return the PassInfo data structure that corresponds to this
89 /// pass... If the pass has not been registered, this will return null.
91 const PassInfo *getPassInfo() const;
93 /// runPass - Run this pass, returning true if a modification was made to the
94 /// module argument. This should be implemented by all concrete subclasses.
96 virtual bool runPass(Module &M) { return false; }
97 virtual bool runPass(BasicBlock&) { return false; }
99 /// print - Print out the internal state of the pass. This is called by
100 /// Analyze to print out the contents of an analysis. Otherwise it is not
101 /// necessary to implement this method. Beware that the module pointer MAY be
102 /// null. This automatically forwards to a virtual function that does not
103 /// provide the Module* in case the analysis doesn't need it it can just be
106 virtual void print(std::ostream &O, const Module *M) const;
107 void print(std::ostream *O, const Module *M) const { if (O) print(*O, M); }
108 void dump() const; // dump - call print(std::cerr, 0);
110 virtual void assignPassManager(PMStack &PMS) {}
111 // Access AnalysisResolver
112 inline void setResolver(AnalysisResolver *AR) { Resolver = AR; }
113 inline AnalysisResolver *getResolver() { return Resolver; }
115 /// getAnalysisUsage - This function should be overriden by passes that need
116 /// analysis information to do their job. If a pass specifies that it uses a
117 /// particular analysis result to this function, it can then use the
118 /// getAnalysis<AnalysisType>() function, below.
120 virtual void getAnalysisUsage(AnalysisUsage &Info) const {
121 // By default, no analysis results are used, all are invalidated.
124 /// releaseMemory() - This member can be implemented by a pass if it wants to
125 /// be able to release its memory when it is no longer needed. The default
126 /// behavior of passes is to hold onto memory for the entire duration of their
127 /// lifetime (which is the entire compile time). For pipelined passes, this
128 /// is not a big deal because that memory gets recycled every time the pass is
129 /// invoked on another program unit. For IP passes, it is more important to
130 /// free memory when it is unused.
132 /// Optionally implement this function to release pass memory when it is no
135 virtual void releaseMemory() {}
137 // dumpPassStructure - Implement the -debug-passes=PassStructure option
138 virtual void dumpPassStructure(unsigned Offset = 0);
140 template<typename AnalysisClass>
141 static const PassInfo *getClassPassInfo() {
142 return lookupPassInfo(typeid(AnalysisClass));
145 // lookupPassInfo - Return the pass info object for the specified pass class,
146 // or null if it is not known.
147 static const PassInfo *lookupPassInfo(const std::type_info &TI);
149 /// getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses
150 /// to get to the analysis information that might be around that needs to be
151 /// updated. This is different than getAnalysis in that it can fail (ie the
152 /// analysis results haven't been computed), so should only be used if you
153 /// provide the capability to update an analysis that exists. This method is
154 /// often used by transformation APIs to update analysis results for a pass
155 /// automatically as the transform is performed.
157 template<typename AnalysisType>
158 AnalysisType *getAnalysisToUpdate() const; // Defined in PassAnalysisSupport.h
160 /// mustPreserveAnalysisID - This method serves the same function as
161 /// getAnalysisToUpdate, but works if you just have an AnalysisID. This
162 /// obviously cannot give you a properly typed instance of the class if you
163 /// don't have the class name available (use getAnalysisToUpdate if you do),
164 /// but it can tell you if you need to preserve the pass at least.
166 bool mustPreserveAnalysisID(const PassInfo *AnalysisID) const;
168 /// getAnalysis<AnalysisType>() - This function is used by subclasses to get
169 /// to the analysis information that they claim to use by overriding the
170 /// getAnalysisUsage function.
172 template<typename AnalysisType>
173 AnalysisType &getAnalysis() const; // Defined in PassAnalysisSupport.h
175 template<typename AnalysisType>
176 AnalysisType &getAnalysisID(const PassInfo *PI) const;
179 template<typename Trait> friend class PassManagerT;
180 friend class ModulePassManager;
181 friend class FunctionPassManagerT;
182 friend class BasicBlockPassManager;
185 inline std::ostream &operator<<(std::ostream &OS, const Pass &P) {
186 P.print(OS, 0); return OS;
189 //===----------------------------------------------------------------------===//
190 /// ModulePass class - This class is used to implement unstructured
191 /// interprocedural optimizations and analyses. ModulePasses may do anything
192 /// they want to the program.
194 class ModulePass : public Pass {
196 /// runOnModule - Virtual method overriden by subclasses to process the module
197 /// being operated on.
198 virtual bool runOnModule(Module &M) = 0;
200 virtual bool runPass(Module &M) { return runOnModule(M); }
201 virtual bool runPass(BasicBlock&) { return false; }
203 virtual void assignPassManager(PMStack &PMS);
204 // Force out-of-line virtual method.
205 virtual ~ModulePass();
209 //===----------------------------------------------------------------------===//
210 /// ImmutablePass class - This class is used to provide information that does
211 /// not need to be run. This is useful for things like target information and
212 /// "basic" versions of AnalysisGroups.
214 class ImmutablePass : public ModulePass {
216 /// initializePass - This method may be overriden by immutable passes to allow
217 /// them to perform various initialization actions they require. This is
218 /// primarily because an ImmutablePass can "require" another ImmutablePass,
219 /// and if it does, the overloaded version of initializePass may get access to
220 /// these passes with getAnalysis<>.
222 virtual void initializePass() {}
224 /// ImmutablePasses are never run.
226 virtual bool runOnModule(Module &M) { return false; }
228 // Force out-of-line virtual method.
229 virtual ~ImmutablePass();
232 //===----------------------------------------------------------------------===//
233 /// FunctionPass class - This class is used to implement most global
234 /// optimizations. Optimizations should subclass this class if they meet the
235 /// following constraints:
237 /// 1. Optimizations are organized globally, i.e., a function at a time
238 /// 2. Optimizing a function does not cause the addition or removal of any
239 /// functions in the module
241 class FunctionPass : public ModulePass {
243 /// doInitialization - Virtual method overridden by subclasses to do
244 /// any necessary per-module initialization.
246 virtual bool doInitialization(Module &M) { return false; }
248 /// runOnFunction - Virtual method overriden by subclasses to do the
249 /// per-function processing of the pass.
251 virtual bool runOnFunction(Function &F) = 0;
253 /// doFinalization - Virtual method overriden by subclasses to do any post
254 /// processing needed after all passes have run.
256 virtual bool doFinalization(Module &M) { return false; }
258 /// runOnModule - On a module, we run this pass by initializing,
259 /// ronOnFunction'ing once for every function in the module, then by
262 virtual bool runOnModule(Module &M);
264 /// run - On a function, we simply initialize, run the function, then
267 bool run(Function &F);
269 virtual void assignPassManager(PMStack &PMS);
274 //===----------------------------------------------------------------------===//
275 /// BasicBlockPass class - This class is used to implement most local
276 /// optimizations. Optimizations should subclass this class if they
277 /// meet the following constraints:
278 /// 1. Optimizations are local, operating on either a basic block or
279 /// instruction at a time.
280 /// 2. Optimizations do not modify the CFG of the contained function, or any
281 /// other basic block in the function.
282 /// 3. Optimizations conform to all of the constraints of FunctionPasses.
284 class BasicBlockPass : public FunctionPass {
286 /// doInitialization - Virtual method overridden by subclasses to do
287 /// any necessary per-module initialization.
289 virtual bool doInitialization(Module &M) { return false; }
291 /// doInitialization - Virtual method overridden by BasicBlockPass subclasses
292 /// to do any necessary per-function initialization.
294 virtual bool doInitialization(Function &F) { return false; }
296 /// runOnBasicBlock - Virtual method overriden by subclasses to do the
297 /// per-basicblock processing of the pass.
299 virtual bool runOnBasicBlock(BasicBlock &BB) = 0;
301 /// doFinalization - Virtual method overriden by BasicBlockPass subclasses to
302 /// do any post processing needed after all passes have run.
304 virtual bool doFinalization(Function &F) { return false; }
306 /// doFinalization - Virtual method overriden by subclasses to do any post
307 /// processing needed after all passes have run.
309 virtual bool doFinalization(Module &M) { return false; }
312 // To run this pass on a function, we simply call runOnBasicBlock once for
315 bool runOnFunction(Function &F);
317 /// To run directly on the basic block, we initialize, runOnBasicBlock, then
320 virtual bool runPass(Module &M) { return false; }
321 virtual bool runPass(BasicBlock &BB);
323 virtual void assignPassManager(PMStack &PMS);
326 /// Different types of internal pass managers. External pass managers
327 /// (PassManager and FunctionPassManager) are not represented here.
328 /// Ordering of pass manager types is important here.
329 enum PassManagerType {
331 PMT_ModulePassManager = 1, /// MPPassManager
332 PMT_CallGraphPassManager, /// CGPassManager
333 PMT_FunctionPassManager, /// FPPassManager
334 PMT_LoopPassManager, /// LPPassManager
335 PMT_BasicBlockPassManager /// BBPassManager
339 /// Top level pass manager (see PasManager.cpp) maintains active Pass Managers
340 /// using PMStack. Each Pass implements assignPassManager() to connect itself
341 /// with appropriate manager. assignPassManager() walks PMStack to find
342 /// suitable manager.
344 /// PMStack is just a wrapper around standard deque that overrides pop() and
348 typedef std::deque<PMDataManager *>::reverse_iterator iterator;
349 iterator begin() { return S.rbegin(); }
350 iterator end() { return S.rend(); }
352 void handleLastUserOverflow();
355 inline PMDataManager *top() { return S.back(); }
357 inline bool empty() { return S.empty(); }
361 std::deque<PMDataManager *> S;
365 /// If the user specifies the -time-passes argument on an LLVM tool command line
366 /// then the value of this boolean will be true, otherwise false.
367 /// @brief This is the storage for the -time-passes option.
368 extern bool TimePassesIsEnabled;
370 } // End llvm namespace
372 // Include support files that contain important APIs commonly used by Passes,
373 // but that we want to separate out to make it easier to read the header files.
375 #include "llvm/PassSupport.h"
376 #include "llvm/PassAnalysisSupport.h"