1 //===- llvm/Pass.h - Base class for XForm Passes -----------------*- C++ -*--=//
3 // This file defines a base class that indicates that a specified class is a
4 // transformation pass implementation.
6 // Pass's are designed this way so that it is possible to run passes in a cache
7 // and organizationally optimal order without having to specify it at the front
8 // end. This allows arbitrary passes to be strung together and have them
9 // executed as effeciently as possible.
11 // Passes should extend one of the classes below, depending on the guarantees
12 // that it can make about what will be modified as it is run. For example, most
13 // global optimizations should derive from FunctionPass, because they do not add
14 // or delete functions, they operate on the internals of the function.
16 // Note that this file #includes PassSupport.h and PassAnalysisSupport.h (at the
17 // bottom), so the APIs exposed by these files are also automatically available
18 // to all users of this file.
20 //===----------------------------------------------------------------------===//
36 template<class UnitType> class PassManagerT;
37 struct AnalysisResolver;
39 // AnalysisID - Use the PassInfo to identify a pass...
40 typedef const PassInfo* AnalysisID;
42 //===----------------------------------------------------------------------===//
43 /// Pass interface - Implemented by all 'passes'. Subclass this if you are an
44 /// interprocedural optimization or you do not fit into any of the more
45 /// constrained passes described below.
48 friend class AnalysisResolver;
49 AnalysisResolver *Resolver; // AnalysisResolver this pass is owned by...
50 const PassInfo *PassInfoCache;
52 // AnalysisImpls - This keeps track of which passes implement the interfaces
53 // that are required by the current pass (to implement getAnalysis()).
55 std::vector<std::pair<const PassInfo*, Pass*> > AnalysisImpls;
57 void operator=(const Pass&); // DO NOT IMPLEMENT
58 Pass(const Pass &); // DO NOT IMPLEMENT
60 Pass() : Resolver(0), PassInfoCache(0) {}
61 virtual ~Pass() {} // Destructor is virtual so we can be subclassed
63 /// getPassName - Return a nice clean name for a pass. This usually
64 /// implemented in terms of the name that is registered by one of the
65 /// Registration templates, but can be overloaded directly, and if nothing
66 /// else is available, C++ RTTI will be consulted to get a SOMEWHAT
67 /// intelligable name for the pass.
69 virtual const char *getPassName() const;
71 /// getPassInfo - Return the PassInfo data structure that corresponds to this
72 /// pass... If the pass has not been registered, this will return null.
74 const PassInfo *getPassInfo() const;
76 /// run - Run this pass, returning true if a modification was made to the
77 /// module argument. This should be implemented by all concrete subclasses.
79 virtual bool run(Module &M) = 0;
81 /// print - Print out the internal state of the pass. This is called by
82 /// Analyze to print out the contents of an analysis. Otherwise it is not
83 /// neccesary to implement this method. Beware that the module pointer MAY be
84 /// null. This automatically forwards to a virtual function that does not
85 /// provide the Module* in case the analysis doesn't need it it can just be
88 virtual void print(std::ostream &O, const Module *M) const { print(O); }
89 virtual void print(std::ostream &O) const;
90 void dump() const; // dump - call print(std::cerr, 0);
93 /// getAnalysisUsage - This function should be overriden by passes that need
94 /// analysis information to do their job. If a pass specifies that it uses a
95 /// particular analysis result to this function, it can then use the
96 /// getAnalysis<AnalysisType>() function, below.
98 virtual void getAnalysisUsage(AnalysisUsage &Info) const {
99 // By default, no analysis results are used, all are invalidated.
102 /// releaseMemory() - This member can be implemented by a pass if it wants to
103 /// be able to release its memory when it is no longer needed. The default
104 /// behavior of passes is to hold onto memory for the entire duration of their
105 /// lifetime (which is the entire compile time). For pipelined passes, this
106 /// is not a big deal because that memory gets recycled every time the pass is
107 /// invoked on another program unit. For IP passes, it is more important to
108 /// free memory when it is unused.
110 /// Optionally implement this function to release pass memory when it is no
113 virtual void releaseMemory() {}
115 // dumpPassStructure - Implement the -debug-passes=PassStructure option
116 virtual void dumpPassStructure(unsigned Offset = 0);
119 // getPassInfo - Static method to get the pass information from a class name.
120 template<typename AnalysisClass>
121 static const PassInfo *getClassPassInfo() {
122 return lookupPassInfo(typeid(AnalysisClass));
125 // lookupPassInfo - Return the pass info object for the specified pass class,
126 // or null if it is not known.
127 static const PassInfo *lookupPassInfo(const std::type_info &TI);
129 /// getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses
130 /// to get to the analysis information that might be around that needs to be
131 /// updated. This is different than getAnalysis in that it can fail (ie the
132 /// analysis results haven't been computed), so should only be used if you
133 /// provide the capability to update an analysis that exists. This method is
134 /// often used by transformation APIs to update analysis results for a pass
135 /// automatically as the transform is performed.
137 template<typename AnalysisType>
138 AnalysisType *getAnalysisToUpdate() const {
139 assert(Resolver && "Pass not resident in a PassManager object!");
140 const PassInfo *PI = getClassPassInfo<AnalysisType>();
141 if (PI == 0) return 0;
142 return dynamic_cast<AnalysisType*>(Resolver->getAnalysisToUpdate(PI));
145 /// mustPreserveAnalysisID - This method serves the same function as
146 /// getAnalysisToUpdate, but works if you just have an AnalysisID. This
147 /// obviously cannot give you a properly typed instance of the class if you
148 /// don't have the class name available (use getAnalysisToUpdate if you do),
149 /// but it can tell you if you need to preserve the pass at least.
151 bool mustPreserveAnalysisID(const PassInfo *AnalysisID) const;
153 /// getAnalysis<AnalysisType>() - This function is used by subclasses to get
154 /// to the analysis information that they claim to use by overriding the
155 /// getAnalysisUsage function.
157 template<typename AnalysisType>
158 AnalysisType &getAnalysis() const {
159 assert(Resolver && "Pass has not been inserted into a PassManager object!");
160 const PassInfo *PI = getClassPassInfo<AnalysisType>();
161 return getAnalysisID<AnalysisType>(PI);
164 template<typename AnalysisType>
165 AnalysisType &getAnalysisID(const PassInfo *PI) const {
166 assert(Resolver && "Pass has not been inserted into a PassManager object!");
167 assert(PI && "getAnalysis for unregistered pass!");
169 // PI *must* appear in AnalysisImpls. Because the number of passes used
170 // should be a small number, we just do a linear search over a (dense)
172 Pass *ResultPass = 0;
173 for (unsigned i = 0; ; ++i) {
174 assert(i != AnalysisImpls.size() &&
175 "getAnalysis*() called on an analysis that we not "
176 "'required' by pass!");
177 if (AnalysisImpls[i].first == PI) {
178 ResultPass = AnalysisImpls[i].second;
183 // Because the AnalysisType may not be a subclass of pass (for
184 // AnalysisGroups), we must use dynamic_cast here to potentially adjust the
185 // return pointer (because the class may multiply inherit, once from pass,
186 // once from AnalysisType).
188 AnalysisType *Result = dynamic_cast<AnalysisType*>(ResultPass);
189 assert(Result && "Pass does not implement interface required!");
194 friend class PassManagerT<Module>;
195 friend class PassManagerT<Function>;
196 friend class PassManagerT<BasicBlock>;
197 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
200 inline std::ostream &operator<<(std::ostream &OS, const Pass &P) {
201 P.print(OS, 0); return OS;
206 //===----------------------------------------------------------------------===//
207 /// ImmutablePass class - This class is used to provide information that does
208 /// not need to be run. This is useful for things like target information and
209 /// "basic" versions of AnalysisGroups.
211 struct ImmutablePass : public Pass {
212 /// initializePass - This method may be overriden by immutable passes to allow
213 /// them to perform various initialization actions they require. This is
214 /// primarily because an ImmutablePass can "require" another ImmutablePass,
215 /// and if it does, the overloaded version of initializePass may get access to
216 /// these passes with getAnalysis<>.
218 virtual void initializePass() {}
220 /// ImmutablePasses are never run.
222 virtual bool run(Module &M) { return false; }
225 friend class PassManagerT<Module>;
226 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
230 //===----------------------------------------------------------------------===//
231 /// FunctionPass class - This class is used to implement most global
232 /// optimizations. Optimizations should subclass this class if they meet the
233 /// following constraints:
235 /// 1. Optimizations are organized globally, i.e., a function at a time
236 /// 2. Optimizing a function does not cause the addition or removal of any
237 /// functions in the module
239 struct FunctionPass : public Pass {
240 /// doInitialization - Virtual method overridden by subclasses to do
241 /// any neccesary per-module initialization.
243 virtual bool doInitialization(Module &M) { return false; }
245 /// runOnFunction - Virtual method overriden by subclasses to do the
246 /// per-function processing of the pass.
248 virtual bool runOnFunction(Function &F) = 0;
250 /// doFinalization - Virtual method overriden by subclasses to do any post
251 /// processing needed after all passes have run.
253 virtual bool doFinalization(Module &M) { return false; }
255 /// run - On a module, we run this pass by initializing, ronOnFunction'ing
256 /// once for every function in the module, then by finalizing.
258 virtual bool run(Module &M);
260 /// run - On a function, we simply initialize, run the function, then
263 bool run(Function &F);
266 friend class PassManagerT<Module>;
267 friend class PassManagerT<Function>;
268 friend class PassManagerT<BasicBlock>;
269 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
270 virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU);
275 //===----------------------------------------------------------------------===//
276 /// BasicBlockPass class - This class is used to implement most local
277 /// optimizations. Optimizations should subclass this class if they
278 /// meet the following constraints:
279 /// 1. Optimizations are local, operating on either a basic block or
280 /// instruction at a time.
281 /// 2. Optimizations do not modify the CFG of the contained function, or any
282 /// other basic block in the function.
283 /// 3. Optimizations conform to all of the constraints of FunctionPass's.
285 struct BasicBlockPass : public FunctionPass {
286 /// doInitialization - Virtual method overridden by subclasses to do
287 /// any neccesary per-module initialization.
289 virtual bool doInitialization(Module &M) { return false; }
291 /// doInitialization - Virtual method overridden by BasicBlockPass subclasses
292 /// to do any neccesary 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 bool run(BasicBlock &BB);
323 friend class PassManagerT<Function>;
324 friend class PassManagerT<BasicBlock>;
325 virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU);
326 virtual void addToPassManager(PassManagerT<BasicBlock> *PM,AnalysisUsage &AU);
329 // Include support files that contain important APIs commonly used by Passes,
330 // but that we want to separate out to make it easier to read the header files.
332 #include "llvm/PassSupport.h"
333 #include "llvm/PassAnalysisSupport.h"