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 //===----------------------------------------------------------------------===//
47 template<class Trait> class PassManagerT;
48 class BasicBlockPassManager;
49 class FunctionPassManagerT;
50 class ModulePassManager;
51 struct AnalysisResolver;
53 // AnalysisID - Use the PassInfo to identify a pass...
54 typedef const PassInfo* AnalysisID;
56 //===----------------------------------------------------------------------===//
57 /// Pass interface - Implemented by all 'passes'. Subclass this if you are an
58 /// interprocedural optimization or you do not fit into any of the more
59 /// constrained passes described below.
62 friend struct AnalysisResolver;
63 AnalysisResolver *Resolver; // AnalysisResolver this pass is owned by...
64 const PassInfo *PassInfoCache;
66 // AnalysisImpls - This keeps track of which passes implement the interfaces
67 // that are required by the current pass (to implement getAnalysis()).
69 std::vector<std::pair<const PassInfo*, Pass*> > AnalysisImpls;
71 void operator=(const Pass&); // DO NOT IMPLEMENT
72 Pass(const Pass &); // DO NOT IMPLEMENT
74 Pass() : Resolver(0), PassInfoCache(0) {}
75 virtual ~Pass() {} // Destructor is virtual so we can be subclassed
77 /// getPassName - Return a nice clean name for a pass. This usually
78 /// implemented in terms of the name that is registered by one of the
79 /// Registration templates, but can be overloaded directly, and if nothing
80 /// else is available, C++ RTTI will be consulted to get a SOMEWHAT
81 /// intelligible name for the pass.
83 virtual const char *getPassName() const;
85 /// getPassInfo - Return the PassInfo data structure that corresponds to this
86 /// pass... If the pass has not been registered, this will return null.
88 const PassInfo *getPassInfo() const;
90 /// runPass - Run this pass, returning true if a modification was made to the
91 /// module argument. This should be implemented by all concrete subclasses.
93 virtual bool runPass(Module &M) { return false; }
94 virtual bool runPass(BasicBlock&) { return false; }
96 /// print - Print out the internal state of the pass. This is called by
97 /// Analyze to print out the contents of an analysis. Otherwise it is not
98 /// necessary to implement this method. Beware that the module pointer MAY be
99 /// null. This automatically forwards to a virtual function that does not
100 /// provide the Module* in case the analysis doesn't need it it can just be
103 virtual void print(std::ostream &O, const Module *M) const;
104 void dump() const; // dump - call print(std::cerr, 0);
107 /// getAnalysisUsage - This function should be overriden by passes that need
108 /// analysis information to do their job. If a pass specifies that it uses a
109 /// particular analysis result to this function, it can then use the
110 /// getAnalysis<AnalysisType>() function, below.
112 virtual void getAnalysisUsage(AnalysisUsage &Info) const {
113 // By default, no analysis results are used, all are invalidated.
116 /// releaseMemory() - This member can be implemented by a pass if it wants to
117 /// be able to release its memory when it is no longer needed. The default
118 /// behavior of passes is to hold onto memory for the entire duration of their
119 /// lifetime (which is the entire compile time). For pipelined passes, this
120 /// is not a big deal because that memory gets recycled every time the pass is
121 /// invoked on another program unit. For IP passes, it is more important to
122 /// free memory when it is unused.
124 /// Optionally implement this function to release pass memory when it is no
127 virtual void releaseMemory() {}
129 // dumpPassStructure - Implement the -debug-passes=PassStructure option
130 virtual void dumpPassStructure(unsigned Offset = 0);
133 // getPassInfo - Static method to get the pass information from a class name.
134 template<typename AnalysisClass>
135 static const PassInfo *getClassPassInfo() {
136 return lookupPassInfo(typeid(AnalysisClass));
139 // lookupPassInfo - Return the pass info object for the specified pass class,
140 // or null if it is not known.
141 static const PassInfo *lookupPassInfo(const std::type_info &TI);
143 /// getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses
144 /// to get to the analysis information that might be around that needs to be
145 /// updated. This is different than getAnalysis in that it can fail (ie the
146 /// analysis results haven't been computed), so should only be used if you
147 /// provide the capability to update an analysis that exists. This method is
148 /// often used by transformation APIs to update analysis results for a pass
149 /// automatically as the transform is performed.
151 template<typename AnalysisType>
152 AnalysisType *getAnalysisToUpdate() const; // Defined in PassAnalysisSupport.h
154 /// mustPreserveAnalysisID - This method serves the same function as
155 /// getAnalysisToUpdate, but works if you just have an AnalysisID. This
156 /// obviously cannot give you a properly typed instance of the class if you
157 /// don't have the class name available (use getAnalysisToUpdate if you do),
158 /// but it can tell you if you need to preserve the pass at least.
160 bool mustPreserveAnalysisID(const PassInfo *AnalysisID) const;
162 /// getAnalysis<AnalysisType>() - This function is used by subclasses to get
163 /// to the analysis information that they claim to use by overriding the
164 /// getAnalysisUsage function.
166 template<typename AnalysisType>
167 AnalysisType &getAnalysis() const {
168 assert(Resolver && "Pass has not been inserted into a PassManager object!");
169 const PassInfo *PI = getClassPassInfo<AnalysisType>();
170 return getAnalysisID<AnalysisType>(PI);
173 template<typename AnalysisType>
174 AnalysisType &getAnalysisID(const PassInfo *PI) const {
175 assert(Resolver && "Pass has not been inserted into a PassManager object!");
176 assert(PI && "getAnalysis for unregistered pass!");
178 // PI *must* appear in AnalysisImpls. Because the number of passes used
179 // should be a small number, we just do a linear search over a (dense)
181 Pass *ResultPass = 0;
182 for (unsigned i = 0; ; ++i) {
183 assert(i != AnalysisImpls.size() &&
184 "getAnalysis*() called on an analysis that was not "
185 "'required' by pass!");
186 if (AnalysisImpls[i].first == PI) {
187 ResultPass = AnalysisImpls[i].second;
192 // Because the AnalysisType may not be a subclass of pass (for
193 // AnalysisGroups), we must use dynamic_cast here to potentially adjust the
194 // return pointer (because the class may multiply inherit, once from pass,
195 // once from AnalysisType).
197 AnalysisType *Result = dynamic_cast<AnalysisType*>(ResultPass);
198 assert(Result && "Pass does not implement interface required!");
203 template<typename Trait> friend class PassManagerT;
204 friend class ModulePassManager;
205 friend class FunctionPassManagerT;
206 friend class BasicBlockPassManager;
209 inline std::ostream &operator<<(std::ostream &OS, const Pass &P) {
210 P.print(OS, 0); return OS;
213 //===----------------------------------------------------------------------===//
214 /// ModulePass class - This class is used to implement unstructured
215 /// interprocedural optimizations and analyses. ModulePasses may do anything
216 /// they want to the program.
218 class ModulePass : public Pass {
220 /// runOnModule - Virtual method overriden by subclasses to process the module
221 /// being operated on.
222 virtual bool runOnModule(Module &M) = 0;
224 virtual bool runPass(Module &M) { return runOnModule(M); }
225 virtual bool runPass(BasicBlock&) { return false; }
227 virtual void addToPassManager(ModulePassManager *PM, AnalysisUsage &AU);
231 //===----------------------------------------------------------------------===//
232 /// ImmutablePass class - This class is used to provide information that does
233 /// not need to be run. This is useful for things like target information and
234 /// "basic" versions of AnalysisGroups.
236 class ImmutablePass : public ModulePass {
238 /// initializePass - This method may be overriden by immutable passes to allow
239 /// them to perform various initialization actions they require. This is
240 /// primarily because an ImmutablePass can "require" another ImmutablePass,
241 /// and if it does, the overloaded version of initializePass may get access to
242 /// these passes with getAnalysis<>.
244 virtual void initializePass() {}
246 /// ImmutablePasses are never run.
248 virtual bool runOnModule(Module &M) { return false; }
251 template<typename Trait> friend class PassManagerT;
252 friend class ModulePassManager;
253 virtual void addToPassManager(ModulePassManager *PM, AnalysisUsage &AU);
256 //===----------------------------------------------------------------------===//
257 /// FunctionPass class - This class is used to implement most global
258 /// optimizations. Optimizations should subclass this class if they meet the
259 /// following constraints:
261 /// 1. Optimizations are organized globally, i.e., a function at a time
262 /// 2. Optimizing a function does not cause the addition or removal of any
263 /// functions in the module
265 class FunctionPass : public ModulePass {
267 /// doInitialization - Virtual method overridden by subclasses to do
268 /// any necessary per-module initialization.
270 virtual bool doInitialization(Module &M) { return false; }
272 /// runOnFunction - Virtual method overriden by subclasses to do the
273 /// per-function processing of the pass.
275 virtual bool runOnFunction(Function &F) = 0;
277 /// doFinalization - Virtual method overriden by subclasses to do any post
278 /// processing needed after all passes have run.
280 virtual bool doFinalization(Module &M) { return false; }
282 /// runOnModule - On a module, we run this pass by initializing,
283 /// ronOnFunction'ing once for every function in the module, then by
286 virtual bool runOnModule(Module &M);
288 /// run - On a function, we simply initialize, run the function, then
291 bool run(Function &F);
294 template<typename Trait> friend class PassManagerT;
295 friend class ModulePassManager;
296 friend class FunctionPassManagerT;
297 friend class BasicBlockPassManager;
298 virtual void addToPassManager(ModulePassManager *PM, AnalysisUsage &AU);
299 virtual void addToPassManager(FunctionPassManagerT *PM, AnalysisUsage &AU);
304 //===----------------------------------------------------------------------===//
305 /// BasicBlockPass class - This class is used to implement most local
306 /// optimizations. Optimizations should subclass this class if they
307 /// meet the following constraints:
308 /// 1. Optimizations are local, operating on either a basic block or
309 /// instruction at a time.
310 /// 2. Optimizations do not modify the CFG of the contained function, or any
311 /// other basic block in the function.
312 /// 3. Optimizations conform to all of the constraints of FunctionPasses.
314 class BasicBlockPass : public FunctionPass {
316 /// doInitialization - Virtual method overridden by subclasses to do
317 /// any necessary per-module initialization.
319 virtual bool doInitialization(Module &M) { return false; }
321 /// doInitialization - Virtual method overridden by BasicBlockPass subclasses
322 /// to do any necessary per-function initialization.
324 virtual bool doInitialization(Function &F) { return false; }
326 /// runOnBasicBlock - Virtual method overriden by subclasses to do the
327 /// per-basicblock processing of the pass.
329 virtual bool runOnBasicBlock(BasicBlock &BB) = 0;
331 /// doFinalization - Virtual method overriden by BasicBlockPass subclasses to
332 /// do any post processing needed after all passes have run.
334 virtual bool doFinalization(Function &F) { return false; }
336 /// doFinalization - Virtual method overriden by subclasses to do any post
337 /// processing needed after all passes have run.
339 virtual bool doFinalization(Module &M) { return false; }
342 // To run this pass on a function, we simply call runOnBasicBlock once for
345 bool runOnFunction(Function &F);
347 /// To run directly on the basic block, we initialize, runOnBasicBlock, then
350 virtual bool runPass(Module &M) { return false; }
351 virtual bool runPass(BasicBlock &BB);
354 template<typename Trait> friend class PassManagerT;
355 friend class FunctionPassManagerT;
356 friend class BasicBlockPassManager;
357 virtual void addToPassManager(FunctionPassManagerT *PM, AnalysisUsage &AU);
358 virtual void addToPassManager(BasicBlockPassManager *PM,AnalysisUsage &AU);
361 /// If the user specifies the -time-passes argument on an LLVM tool command line
362 /// then the value of this boolean will be true, otherwise false.
363 /// @brief This is the storage for the -time-passes option.
364 extern bool TimePassesIsEnabled;
366 } // End llvm namespace
368 // Include support files that contain important APIs commonly used by Passes,
369 // but that we want to separate out to make it easier to read the header files.
371 #include "llvm/PassSupport.h"
372 #include "llvm/PassAnalysisSupport.h"