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 virtual void setupPassManager(PMStack &PMS) {}
113 // Access AnalysisResolver
114 inline void setResolver(AnalysisResolver *AR) { Resolver = AR; }
115 inline AnalysisResolver *getResolver() { return Resolver; }
117 /// getAnalysisUsage - This function should be overriden by passes that need
118 /// analysis information to do their job. If a pass specifies that it uses a
119 /// particular analysis result to this function, it can then use the
120 /// getAnalysis<AnalysisType>() function, below.
122 virtual void getAnalysisUsage(AnalysisUsage &Info) const {
123 // By default, no analysis results are used, all are invalidated.
126 /// releaseMemory() - This member can be implemented by a pass if it wants to
127 /// be able to release its memory when it is no longer needed. The default
128 /// behavior of passes is to hold onto memory for the entire duration of their
129 /// lifetime (which is the entire compile time). For pipelined passes, this
130 /// is not a big deal because that memory gets recycled every time the pass is
131 /// invoked on another program unit. For IP passes, it is more important to
132 /// free memory when it is unused.
134 /// Optionally implement this function to release pass memory when it is no
137 virtual void releaseMemory() {}
139 // dumpPassStructure - Implement the -debug-passes=PassStructure option
140 virtual void dumpPassStructure(unsigned Offset = 0);
142 template<typename AnalysisClass>
143 static const PassInfo *getClassPassInfo() {
144 return lookupPassInfo(typeid(AnalysisClass));
147 // lookupPassInfo - Return the pass info object for the specified pass class,
148 // or null if it is not known.
149 static const PassInfo *lookupPassInfo(const std::type_info &TI);
151 /// getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses
152 /// to get to the analysis information that might be around that needs to be
153 /// updated. This is different than getAnalysis in that it can fail (ie the
154 /// analysis results haven't been computed), so should only be used if you
155 /// provide the capability to update an analysis that exists. This method is
156 /// often used by transformation APIs to update analysis results for a pass
157 /// automatically as the transform is performed.
159 template<typename AnalysisType>
160 AnalysisType *getAnalysisToUpdate() const; // Defined in PassAnalysisSupport.h
162 /// mustPreserveAnalysisID - This method serves the same function as
163 /// getAnalysisToUpdate, but works if you just have an AnalysisID. This
164 /// obviously cannot give you a properly typed instance of the class if you
165 /// don't have the class name available (use getAnalysisToUpdate if you do),
166 /// but it can tell you if you need to preserve the pass at least.
168 bool mustPreserveAnalysisID(const PassInfo *AnalysisID) const;
170 /// getAnalysis<AnalysisType>() - This function is used by subclasses to get
171 /// to the analysis information that they claim to use by overriding the
172 /// getAnalysisUsage function.
174 template<typename AnalysisType>
175 AnalysisType &getAnalysis() const; // Defined in PassAnalysisSupport.h
177 template<typename AnalysisType>
178 AnalysisType &getAnalysisID(const PassInfo *PI) const;
181 template<typename Trait> friend class PassManagerT;
182 friend class ModulePassManager;
183 friend class FunctionPassManagerT;
184 friend class BasicBlockPassManager;
187 inline std::ostream &operator<<(std::ostream &OS, const Pass &P) {
188 P.print(OS, 0); return OS;
191 //===----------------------------------------------------------------------===//
192 /// ModulePass class - This class is used to implement unstructured
193 /// interprocedural optimizations and analyses. ModulePasses may do anything
194 /// they want to the program.
196 class ModulePass : public Pass {
198 /// runOnModule - Virtual method overriden by subclasses to process the module
199 /// being operated on.
200 virtual bool runOnModule(Module &M) = 0;
202 virtual bool runPass(Module &M) { return runOnModule(M); }
203 virtual bool runPass(BasicBlock&) { return false; }
205 virtual void assignPassManager(PMStack &PMS);
207 // Force out-of-line virtual method.
208 virtual ~ModulePass();
212 //===----------------------------------------------------------------------===//
213 /// ImmutablePass class - This class is used to provide information that does
214 /// not need to be run. This is useful for things like target information and
215 /// "basic" versions of AnalysisGroups.
217 class ImmutablePass : public ModulePass {
219 /// initializePass - This method may be overriden by immutable passes to allow
220 /// them to perform various initialization actions they require. This is
221 /// primarily because an ImmutablePass can "require" another ImmutablePass,
222 /// and if it does, the overloaded version of initializePass may get access to
223 /// these passes with getAnalysis<>.
225 virtual void initializePass() {}
227 /// ImmutablePasses are never run.
229 virtual bool runOnModule(Module &M) { return false; }
231 // Force out-of-line virtual method.
232 virtual ~ImmutablePass();
235 //===----------------------------------------------------------------------===//
236 /// FunctionPass class - This class is used to implement most global
237 /// optimizations. Optimizations should subclass this class if they meet the
238 /// following constraints:
240 /// 1. Optimizations are organized globally, i.e., a function at a time
241 /// 2. Optimizing a function does not cause the addition or removal of any
242 /// functions in the module
244 class FunctionPass : public ModulePass {
246 /// doInitialization - Virtual method overridden by subclasses to do
247 /// any necessary per-module initialization.
249 virtual bool doInitialization(Module &M) { return false; }
251 /// runOnFunction - Virtual method overriden by subclasses to do the
252 /// per-function processing of the pass.
254 virtual bool runOnFunction(Function &F) = 0;
256 /// doFinalization - Virtual method overriden by subclasses to do any post
257 /// processing needed after all passes have run.
259 virtual bool doFinalization(Module &M) { return false; }
261 /// runOnModule - On a module, we run this pass by initializing,
262 /// ronOnFunction'ing once for every function in the module, then by
265 virtual bool runOnModule(Module &M);
267 /// run - On a function, we simply initialize, run the function, then
270 bool run(Function &F);
272 virtual void assignPassManager(PMStack &PMS);
273 virtual void setupPassManager(PMStack &PMS);
278 //===----------------------------------------------------------------------===//
279 /// BasicBlockPass class - This class is used to implement most local
280 /// optimizations. Optimizations should subclass this class if they
281 /// meet the following constraints:
282 /// 1. Optimizations are local, operating on either a basic block or
283 /// instruction at a time.
284 /// 2. Optimizations do not modify the CFG of the contained function, or any
285 /// other basic block in the function.
286 /// 3. Optimizations conform to all of the constraints of FunctionPasses.
288 class BasicBlockPass : public FunctionPass {
290 /// doInitialization - Virtual method overridden by subclasses to do
291 /// any necessary per-module initialization.
293 virtual bool doInitialization(Module &M) { return false; }
295 /// doInitialization - Virtual method overridden by BasicBlockPass subclasses
296 /// to do any necessary per-function initialization.
298 virtual bool doInitialization(Function &F) { return false; }
300 /// runOnBasicBlock - Virtual method overriden by subclasses to do the
301 /// per-basicblock processing of the pass.
303 virtual bool runOnBasicBlock(BasicBlock &BB) = 0;
305 /// doFinalization - Virtual method overriden by BasicBlockPass subclasses to
306 /// do any post processing needed after all passes have run.
308 virtual bool doFinalization(Function &F) { return false; }
310 /// doFinalization - Virtual method overriden by subclasses to do any post
311 /// processing needed after all passes have run.
313 virtual bool doFinalization(Module &M) { return false; }
316 // To run this pass on a function, we simply call runOnBasicBlock once for
319 bool runOnFunction(Function &F);
321 /// To run directly on the basic block, we initialize, runOnBasicBlock, then
324 virtual bool runPass(Module &M) { return false; }
325 virtual bool runPass(BasicBlock &BB);
327 virtual void assignPassManager(PMStack &PMS);
328 virtual void setupPassManager(PMStack &PMS);
331 /// Different types of internal pass managers. External pass managers
332 /// (PassManager and FunctionPassManager) are not represented here.
333 /// Ordering of pass manager types is important here.
334 enum PassManagerType {
336 PMT_ModulePassManager = 1, /// MPPassManager
337 PMT_CallGraphPassManager, /// CGPassManager
338 PMT_FunctionPassManager, /// FPPassManager
339 PMT_LoopPassManager, /// LPPassManager
340 PMT_BasicBlockPassManager /// BBPassManager
344 /// Top level pass manager (see PasManager.cpp) maintains active Pass Managers
345 /// using PMStack. Each Pass implements setupPassManager() and
346 /// assignPassManager() to connect itself with appropriate manager.
347 /// setupPassManager() creates new pass manager if required before adding
348 /// required analysis passes. assignPassManager() walks PMStack to find
349 /// suitable manager.
351 /// PMStack is just a wrapper around standard deque that overrides pop() and
355 typedef std::deque<PMDataManager *>::reverse_iterator iterator;
356 iterator begin() { return S.rbegin(); }
357 iterator end() { return S.rend(); }
359 void handleLastUserOverflow();
362 inline PMDataManager *top() { return S.back(); }
364 inline bool empty() { return S.empty(); }
368 std::deque<PMDataManager *> S;
372 /// If the user specifies the -time-passes argument on an LLVM tool command line
373 /// then the value of this boolean will be true, otherwise false.
374 /// @brief This is the storage for the -time-passes option.
375 extern bool TimePassesIsEnabled;
377 } // End llvm namespace
379 // Include support files that contain important APIs commonly used by Passes,
380 // but that we want to separate out to make it easier to read the header files.
382 #include "llvm/PassSupport.h"
383 #include "llvm/PassAnalysisSupport.h"