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 // Pass's 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 //===----------------------------------------------------------------------===//
47 template<class UnitType> class PassManagerT;
48 struct AnalysisResolver;
50 // AnalysisID - Use the PassInfo to identify a pass...
51 typedef const PassInfo* AnalysisID;
53 //===----------------------------------------------------------------------===//
54 /// Pass interface - Implemented by all 'passes'. Subclass this if you are an
55 /// interprocedural optimization or you do not fit into any of the more
56 /// constrained passes described below.
59 friend struct AnalysisResolver;
60 AnalysisResolver *Resolver; // AnalysisResolver this pass is owned by...
61 const PassInfo *PassInfoCache;
63 // AnalysisImpls - This keeps track of which passes implement the interfaces
64 // that are required by the current pass (to implement getAnalysis()).
66 std::vector<std::pair<const PassInfo*, Pass*> > AnalysisImpls;
68 void operator=(const Pass&); // DO NOT IMPLEMENT
69 Pass(const Pass &); // DO NOT IMPLEMENT
71 Pass() : Resolver(0), PassInfoCache(0) {}
72 virtual ~Pass() {} // Destructor is virtual so we can be subclassed
74 /// getPassName - Return a nice clean name for a pass. This usually
75 /// implemented in terms of the name that is registered by one of the
76 /// Registration templates, but can be overloaded directly, and if nothing
77 /// else is available, C++ RTTI will be consulted to get a SOMEWHAT
78 /// intelligible name for the pass.
80 virtual const char *getPassName() const;
82 /// getPassInfo - Return the PassInfo data structure that corresponds to this
83 /// pass... If the pass has not been registered, this will return null.
85 const PassInfo *getPassInfo() const;
87 /// runPass - Run this pass, returning true if a modification was made to the
88 /// module argument. This should be implemented by all concrete subclasses.
90 virtual bool runPass(Module &M) { return false; }
91 virtual bool runPass(BasicBlock&) { return false; }
93 /// print - Print out the internal state of the pass. This is called by
94 /// Analyze to print out the contents of an analysis. Otherwise it is not
95 /// necessary to implement this method. Beware that the module pointer MAY be
96 /// null. This automatically forwards to a virtual function that does not
97 /// provide the Module* in case the analysis doesn't need it it can just be
100 virtual void print(std::ostream &O, const Module *M) const;
101 void dump() const; // dump - call print(std::cerr, 0);
104 /// getAnalysisUsage - This function should be overriden by passes that need
105 /// analysis information to do their job. If a pass specifies that it uses a
106 /// particular analysis result to this function, it can then use the
107 /// getAnalysis<AnalysisType>() function, below.
109 virtual void getAnalysisUsage(AnalysisUsage &Info) const {
110 // By default, no analysis results are used, all are invalidated.
113 /// releaseMemory() - This member can be implemented by a pass if it wants to
114 /// be able to release its memory when it is no longer needed. The default
115 /// behavior of passes is to hold onto memory for the entire duration of their
116 /// lifetime (which is the entire compile time). For pipelined passes, this
117 /// is not a big deal because that memory gets recycled every time the pass is
118 /// invoked on another program unit. For IP passes, it is more important to
119 /// free memory when it is unused.
121 /// Optionally implement this function to release pass memory when it is no
124 virtual void releaseMemory() {}
126 // dumpPassStructure - Implement the -debug-passes=PassStructure option
127 virtual void dumpPassStructure(unsigned Offset = 0);
130 // getPassInfo - Static method to get the pass information from a class name.
131 template<typename AnalysisClass>
132 static const PassInfo *getClassPassInfo() {
133 return lookupPassInfo(typeid(AnalysisClass));
136 // lookupPassInfo - Return the pass info object for the specified pass class,
137 // or null if it is not known.
138 static const PassInfo *lookupPassInfo(const std::type_info &TI);
140 /// getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses
141 /// to get to the analysis information that might be around that needs to be
142 /// updated. This is different than getAnalysis in that it can fail (ie the
143 /// analysis results haven't been computed), so should only be used if you
144 /// provide the capability to update an analysis that exists. This method is
145 /// often used by transformation APIs to update analysis results for a pass
146 /// automatically as the transform is performed.
148 template<typename AnalysisType>
149 AnalysisType *getAnalysisToUpdate() const; // Defined in PassAnalysisSupport.h
151 /// mustPreserveAnalysisID - This method serves the same function as
152 /// getAnalysisToUpdate, but works if you just have an AnalysisID. This
153 /// obviously cannot give you a properly typed instance of the class if you
154 /// don't have the class name available (use getAnalysisToUpdate if you do),
155 /// but it can tell you if you need to preserve the pass at least.
157 bool mustPreserveAnalysisID(const PassInfo *AnalysisID) const;
159 /// getAnalysis<AnalysisType>() - This function is used by subclasses to get
160 /// to the analysis information that they claim to use by overriding the
161 /// getAnalysisUsage function.
163 template<typename AnalysisType>
164 AnalysisType &getAnalysis() const {
165 assert(Resolver && "Pass has not been inserted into a PassManager object!");
166 const PassInfo *PI = getClassPassInfo<AnalysisType>();
167 return getAnalysisID<AnalysisType>(PI);
170 template<typename AnalysisType>
171 AnalysisType &getAnalysisID(const PassInfo *PI) const {
172 assert(Resolver && "Pass has not been inserted into a PassManager object!");
173 assert(PI && "getAnalysis for unregistered pass!");
175 // PI *must* appear in AnalysisImpls. Because the number of passes used
176 // should be a small number, we just do a linear search over a (dense)
178 Pass *ResultPass = 0;
179 for (unsigned i = 0; ; ++i) {
180 assert(i != AnalysisImpls.size() &&
181 "getAnalysis*() called on an analysis that was not "
182 "'required' by pass!");
183 if (AnalysisImpls[i].first == PI) {
184 ResultPass = AnalysisImpls[i].second;
189 // Because the AnalysisType may not be a subclass of pass (for
190 // AnalysisGroups), we must use dynamic_cast here to potentially adjust the
191 // return pointer (because the class may multiply inherit, once from pass,
192 // once from AnalysisType).
194 AnalysisType *Result = dynamic_cast<AnalysisType*>(ResultPass);
195 assert(Result && "Pass does not implement interface required!");
200 friend class PassManagerT<Module>;
201 friend class PassManagerT<Function>;
202 friend class PassManagerT<BasicBlock>;
205 inline std::ostream &operator<<(std::ostream &OS, const Pass &P) {
206 P.print(OS, 0); return OS;
209 //===----------------------------------------------------------------------===//
210 /// ModulePass class - This class is used to implement unstructured
211 /// interprocedural optimizations and analyses. ModulePass's may do anything
212 /// they want to the program.
214 class ModulePass : public Pass {
216 /// runOnModule - Virtual method overriden by subclasses to process the module
217 /// being operated on.
218 virtual bool runOnModule(Module &M) = 0;
220 virtual bool runPass(Module &M) { return runOnModule(M); }
221 virtual bool runPass(BasicBlock&) { return false; }
223 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
227 //===----------------------------------------------------------------------===//
228 /// ImmutablePass class - This class is used to provide information that does
229 /// not need to be run. This is useful for things like target information and
230 /// "basic" versions of AnalysisGroups.
232 class ImmutablePass : public ModulePass {
234 /// initializePass - This method may be overriden by immutable passes to allow
235 /// them to perform various initialization actions they require. This is
236 /// primarily because an ImmutablePass can "require" another ImmutablePass,
237 /// and if it does, the overloaded version of initializePass may get access to
238 /// these passes with getAnalysis<>.
240 virtual void initializePass() {}
242 /// ImmutablePasses are never run.
244 virtual bool runOnModule(Module &M) { return false; }
247 friend class PassManagerT<Module>;
248 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
251 //===----------------------------------------------------------------------===//
252 /// FunctionPass class - This class is used to implement most global
253 /// optimizations. Optimizations should subclass this class if they meet the
254 /// following constraints:
256 /// 1. Optimizations are organized globally, i.e., a function at a time
257 /// 2. Optimizing a function does not cause the addition or removal of any
258 /// functions in the module
260 class FunctionPass : public ModulePass {
262 /// doInitialization - Virtual method overridden by subclasses to do
263 /// any necessary per-module initialization.
265 virtual bool doInitialization(Module &M) { return false; }
267 /// runOnFunction - Virtual method overriden by subclasses to do the
268 /// per-function processing of the pass.
270 virtual bool runOnFunction(Function &F) = 0;
272 /// doFinalization - Virtual method overriden by subclasses to do any post
273 /// processing needed after all passes have run.
275 virtual bool doFinalization(Module &M) { return false; }
277 /// runOnModule - On a module, we run this pass by initializing,
278 /// ronOnFunction'ing once for every function in the module, then by
281 virtual bool runOnModule(Module &M);
283 /// run - On a function, we simply initialize, run the function, then
286 bool run(Function &F);
289 friend class PassManagerT<Module>;
290 friend class PassManagerT<Function>;
291 friend class PassManagerT<BasicBlock>;
292 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
293 virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU);
298 //===----------------------------------------------------------------------===//
299 /// BasicBlockPass class - This class is used to implement most local
300 /// optimizations. Optimizations should subclass this class if they
301 /// meet the following constraints:
302 /// 1. Optimizations are local, operating on either a basic block or
303 /// instruction at a time.
304 /// 2. Optimizations do not modify the CFG of the contained function, or any
305 /// other basic block in the function.
306 /// 3. Optimizations conform to all of the constraints of FunctionPass's.
308 struct BasicBlockPass : public FunctionPass {
309 /// doInitialization - Virtual method overridden by subclasses to do
310 /// any necessary per-module initialization.
312 virtual bool doInitialization(Module &M) { return false; }
314 /// doInitialization - Virtual method overridden by BasicBlockPass subclasses
315 /// to do any necessary per-function initialization.
317 virtual bool doInitialization(Function &F) { return false; }
319 /// runOnBasicBlock - Virtual method overriden by subclasses to do the
320 /// per-basicblock processing of the pass.
322 virtual bool runOnBasicBlock(BasicBlock &BB) = 0;
324 /// doFinalization - Virtual method overriden by BasicBlockPass subclasses to
325 /// do any post processing needed after all passes have run.
327 virtual bool doFinalization(Function &F) { return false; }
329 /// doFinalization - Virtual method overriden by subclasses to do any post
330 /// processing needed after all passes have run.
332 virtual bool doFinalization(Module &M) { return false; }
335 // To run this pass on a function, we simply call runOnBasicBlock once for
338 bool runOnFunction(Function &F);
340 /// To run directly on the basic block, we initialize, runOnBasicBlock, then
343 virtual bool runPass(Module &M) { return false; }
344 virtual bool runPass(BasicBlock &BB);
347 friend class PassManagerT<Function>;
348 friend class PassManagerT<BasicBlock>;
349 virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU);
350 virtual void addToPassManager(PassManagerT<BasicBlock> *PM,AnalysisUsage &AU);
353 /// If the user specifies the -time-passes argument on an LLVM tool command line
354 /// then the value of this boolean will be true, otherwise false.
355 /// @brief This is the storage for the -time-passes option.
356 extern bool TimePassesIsEnabled;
358 } // End llvm namespace
360 // Include support files that contain important APIs commonly used by Passes,
361 // but that we want to separate out to make it easier to read the header files.
363 #include "llvm/PassSupport.h"
364 #include "llvm/PassAnalysisSupport.h"