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"
48 template<class Trait> class PassManagerT;
49 class BasicBlockPassManager;
50 class FunctionPassManagerT;
51 class ModulePassManager;
52 struct AnalysisResolver;
54 // AnalysisID - Use the PassInfo to identify a pass...
55 typedef const PassInfo* AnalysisID;
57 //===----------------------------------------------------------------------===//
58 /// Pass interface - Implemented by all 'passes'. Subclass this if you are an
59 /// interprocedural optimization or you do not fit into any of the more
60 /// constrained passes described below.
63 friend struct AnalysisResolver;
64 AnalysisResolver *Resolver; // AnalysisResolver this pass is owned by...
65 const PassInfo *PassInfoCache;
67 // AnalysisImpls - This keeps track of which passes implement the interfaces
68 // that are required by the current pass (to implement getAnalysis()).
70 std::vector<std::pair<const PassInfo*, Pass*> > AnalysisImpls;
72 void operator=(const Pass&); // DO NOT IMPLEMENT
73 Pass(const Pass &); // DO NOT IMPLEMENT
75 Pass() : Resolver(0), PassInfoCache(0) {}
76 virtual ~Pass() {} // Destructor is virtual so we can be subclassed
78 /// getPassName - Return a nice clean name for a pass. This usually
79 /// implemented in terms of the name that is registered by one of the
80 /// Registration templates, but can be overloaded directly, and if nothing
81 /// else is available, C++ RTTI will be consulted to get a SOMEWHAT
82 /// intelligible name for the pass.
84 virtual const char *getPassName() const;
86 /// getPassInfo - Return the PassInfo data structure that corresponds to this
87 /// pass... If the pass has not been registered, this will return null.
89 const PassInfo *getPassInfo() const;
91 /// runPass - Run this pass, returning true if a modification was made to the
92 /// module argument. This should be implemented by all concrete subclasses.
94 virtual bool runPass(Module &M) { return false; }
95 virtual bool runPass(BasicBlock&) { return false; }
97 /// print - Print out the internal state of the pass. This is called by
98 /// Analyze to print out the contents of an analysis. Otherwise it is not
99 /// necessary to implement this method. Beware that the module pointer MAY be
100 /// null. This automatically forwards to a virtual function that does not
101 /// provide the Module* in case the analysis doesn't need it it can just be
104 void print(OStream &O, const Module *M) const {
105 if (O.stream()) print(*O.stream(), M);
107 virtual void print(std::ostream &O, const Module *M) const;
108 void dump() const; // dump - call print(std::cerr, 0);
111 /// getAnalysisUsage - This function should be overriden by passes that need
112 /// analysis information to do their job. If a pass specifies that it uses a
113 /// particular analysis result to this function, it can then use the
114 /// getAnalysis<AnalysisType>() function, below.
116 virtual void getAnalysisUsage(AnalysisUsage &Info) const {
117 // By default, no analysis results are used, all are invalidated.
120 /// releaseMemory() - This member can be implemented by a pass if it wants to
121 /// be able to release its memory when it is no longer needed. The default
122 /// behavior of passes is to hold onto memory for the entire duration of their
123 /// lifetime (which is the entire compile time). For pipelined passes, this
124 /// is not a big deal because that memory gets recycled every time the pass is
125 /// invoked on another program unit. For IP passes, it is more important to
126 /// free memory when it is unused.
128 /// Optionally implement this function to release pass memory when it is no
131 virtual void releaseMemory() {}
133 // dumpPassStructure - Implement the -debug-passes=PassStructure option
134 virtual void dumpPassStructure(unsigned Offset = 0);
137 // getPassInfo - Static method to get the pass information from a class name.
138 template<typename AnalysisClass>
139 static const PassInfo *getClassPassInfo() {
140 return lookupPassInfo(typeid(AnalysisClass));
143 // lookupPassInfo - Return the pass info object for the specified pass class,
144 // or null if it is not known.
145 static const PassInfo *lookupPassInfo(const std::type_info &TI);
147 /// getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses
148 /// to get to the analysis information that might be around that needs to be
149 /// updated. This is different than getAnalysis in that it can fail (ie the
150 /// analysis results haven't been computed), so should only be used if you
151 /// provide the capability to update an analysis that exists. This method is
152 /// often used by transformation APIs to update analysis results for a pass
153 /// automatically as the transform is performed.
155 template<typename AnalysisType>
156 AnalysisType *getAnalysisToUpdate() const; // Defined in PassAnalysisSupport.h
158 /// mustPreserveAnalysisID - This method serves the same function as
159 /// getAnalysisToUpdate, but works if you just have an AnalysisID. This
160 /// obviously cannot give you a properly typed instance of the class if you
161 /// don't have the class name available (use getAnalysisToUpdate if you do),
162 /// but it can tell you if you need to preserve the pass at least.
164 bool mustPreserveAnalysisID(const PassInfo *AnalysisID) const;
166 /// getAnalysis<AnalysisType>() - This function is used by subclasses to get
167 /// to the analysis information that they claim to use by overriding the
168 /// getAnalysisUsage function.
170 template<typename AnalysisType>
171 AnalysisType &getAnalysis() const {
172 assert(Resolver && "Pass has not been inserted into a PassManager object!");
173 const PassInfo *PI = getClassPassInfo<AnalysisType>();
174 return getAnalysisID<AnalysisType>(PI);
177 template<typename AnalysisType>
178 AnalysisType &getAnalysisID(const PassInfo *PI) const {
179 assert(Resolver && "Pass has not been inserted into a PassManager object!");
180 assert(PI && "getAnalysis for unregistered pass!");
182 // PI *must* appear in AnalysisImpls. Because the number of passes used
183 // should be a small number, we just do a linear search over a (dense)
185 Pass *ResultPass = 0;
186 for (unsigned i = 0; ; ++i) {
187 assert(i != AnalysisImpls.size() &&
188 "getAnalysis*() called on an analysis that was not "
189 "'required' by pass!");
190 if (AnalysisImpls[i].first == PI) {
191 ResultPass = AnalysisImpls[i].second;
196 // Because the AnalysisType may not be a subclass of pass (for
197 // AnalysisGroups), we must use dynamic_cast here to potentially adjust the
198 // return pointer (because the class may multiply inherit, once from pass,
199 // once from AnalysisType).
201 AnalysisType *Result = dynamic_cast<AnalysisType*>(ResultPass);
202 assert(Result && "Pass does not implement interface required!");
207 template<typename Trait> friend class PassManagerT;
208 friend class ModulePassManager;
209 friend class FunctionPassManagerT;
210 friend class BasicBlockPassManager;
213 inline std::ostream &operator<<(std::ostream &OS, const Pass &P) {
214 P.print(OS, 0); return OS;
217 //===----------------------------------------------------------------------===//
218 /// ModulePass class - This class is used to implement unstructured
219 /// interprocedural optimizations and analyses. ModulePasses may do anything
220 /// they want to the program.
222 class ModulePass : public Pass {
224 /// runOnModule - Virtual method overriden by subclasses to process the module
225 /// being operated on.
226 virtual bool runOnModule(Module &M) = 0;
228 virtual bool runPass(Module &M) { return runOnModule(M); }
229 virtual bool runPass(BasicBlock&) { return false; }
231 virtual void addToPassManager(ModulePassManager *PM, AnalysisUsage &AU);
235 //===----------------------------------------------------------------------===//
236 /// ImmutablePass class - This class is used to provide information that does
237 /// not need to be run. This is useful for things like target information and
238 /// "basic" versions of AnalysisGroups.
240 class ImmutablePass : public ModulePass {
242 /// initializePass - This method may be overriden by immutable passes to allow
243 /// them to perform various initialization actions they require. This is
244 /// primarily because an ImmutablePass can "require" another ImmutablePass,
245 /// and if it does, the overloaded version of initializePass may get access to
246 /// these passes with getAnalysis<>.
248 virtual void initializePass() {}
250 /// ImmutablePasses are never run.
252 virtual bool runOnModule(Module &M) { return false; }
255 template<typename Trait> friend class PassManagerT;
256 friend class ModulePassManager;
257 virtual void addToPassManager(ModulePassManager *PM, AnalysisUsage &AU);
260 //===----------------------------------------------------------------------===//
261 /// FunctionPass class - This class is used to implement most global
262 /// optimizations. Optimizations should subclass this class if they meet the
263 /// following constraints:
265 /// 1. Optimizations are organized globally, i.e., a function at a time
266 /// 2. Optimizing a function does not cause the addition or removal of any
267 /// functions in the module
269 class FunctionPass : public ModulePass {
271 /// doInitialization - Virtual method overridden by subclasses to do
272 /// any necessary per-module initialization.
274 virtual bool doInitialization(Module &M) { return false; }
276 /// runOnFunction - Virtual method overriden by subclasses to do the
277 /// per-function processing of the pass.
279 virtual bool runOnFunction(Function &F) = 0;
281 /// doFinalization - Virtual method overriden by subclasses to do any post
282 /// processing needed after all passes have run.
284 virtual bool doFinalization(Module &M) { return false; }
286 /// runOnModule - On a module, we run this pass by initializing,
287 /// ronOnFunction'ing once for every function in the module, then by
290 virtual bool runOnModule(Module &M);
292 /// run - On a function, we simply initialize, run the function, then
295 bool run(Function &F);
298 template<typename Trait> friend class PassManagerT;
299 friend class ModulePassManager;
300 friend class FunctionPassManagerT;
301 friend class BasicBlockPassManager;
302 virtual void addToPassManager(ModulePassManager *PM, AnalysisUsage &AU);
303 virtual void addToPassManager(FunctionPassManagerT *PM, AnalysisUsage &AU);
308 //===----------------------------------------------------------------------===//
309 /// BasicBlockPass class - This class is used to implement most local
310 /// optimizations. Optimizations should subclass this class if they
311 /// meet the following constraints:
312 /// 1. Optimizations are local, operating on either a basic block or
313 /// instruction at a time.
314 /// 2. Optimizations do not modify the CFG of the contained function, or any
315 /// other basic block in the function.
316 /// 3. Optimizations conform to all of the constraints of FunctionPasses.
318 class BasicBlockPass : public FunctionPass {
320 /// doInitialization - Virtual method overridden by subclasses to do
321 /// any necessary per-module initialization.
323 virtual bool doInitialization(Module &M) { return false; }
325 /// doInitialization - Virtual method overridden by BasicBlockPass subclasses
326 /// to do any necessary per-function initialization.
328 virtual bool doInitialization(Function &F) { return false; }
330 /// runOnBasicBlock - Virtual method overriden by subclasses to do the
331 /// per-basicblock processing of the pass.
333 virtual bool runOnBasicBlock(BasicBlock &BB) = 0;
335 /// doFinalization - Virtual method overriden by BasicBlockPass subclasses to
336 /// do any post processing needed after all passes have run.
338 virtual bool doFinalization(Function &F) { return false; }
340 /// doFinalization - Virtual method overriden by subclasses to do any post
341 /// processing needed after all passes have run.
343 virtual bool doFinalization(Module &M) { return false; }
346 // To run this pass on a function, we simply call runOnBasicBlock once for
349 bool runOnFunction(Function &F);
351 /// To run directly on the basic block, we initialize, runOnBasicBlock, then
354 virtual bool runPass(Module &M) { return false; }
355 virtual bool runPass(BasicBlock &BB);
358 template<typename Trait> friend class PassManagerT;
359 friend class FunctionPassManagerT;
360 friend class BasicBlockPassManager;
361 virtual void addToPassManager(ModulePassManager *PM, AnalysisUsage &AU) {
362 FunctionPass::addToPassManager(PM, AU);
364 virtual void addToPassManager(FunctionPassManagerT *PM, AnalysisUsage &AU);
365 virtual void addToPassManager(BasicBlockPassManager *PM,AnalysisUsage &AU);
368 /// If the user specifies the -time-passes argument on an LLVM tool command line
369 /// then the value of this boolean will be true, otherwise false.
370 /// @brief This is the storage for the -time-passes option.
371 extern bool TimePassesIsEnabled;
373 } // End llvm namespace
375 // Include support files that contain important APIs commonly used by Passes,
376 // but that we want to separate out to make it easier to read the header files.
378 #include "llvm/PassSupport.h"
379 #include "llvm/PassAnalysisSupport.h"