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 //===----------------------------------------------------------------------===//
29 template<class UnitType> class PassManagerT;
30 struct AnalysisResolver;
32 //===----------------------------------------------------------------------===//
33 // Pass interface - Implemented by all 'passes'. Subclass this if you are an
34 // interprocedural optimization or you do not fit into any of the more
35 // constrained passes described below.
38 friend class AnalysisResolver;
39 AnalysisResolver *Resolver; // AnalysisResolver this pass is owned by...
41 inline Pass(AnalysisResolver *AR = 0) : Resolver(AR) {}
42 inline virtual ~Pass() {} // Destructor is virtual so we can be subclassed
44 // getPassName - Return a nice clean name for a pass. This should be
45 // overloaded by the pass, but if it is not, C++ RTTI will be consulted to get
46 // a SOMEWHAT intelligable name for the pass.
48 virtual const char *getPassName() const;
50 // run - Run this pass, returning true if a modification was made to the
51 // module argument. This should be implemented by all concrete subclasses.
53 virtual bool run(Module &M) = 0;
55 // getAnalysisUsage - This function should be overriden by passes that need
56 // analysis information to do their job. If a pass specifies that it uses a
57 // particular analysis result to this function, it can then use the
58 // getAnalysis<AnalysisType>() function, below.
60 virtual void getAnalysisUsage(AnalysisUsage &Info) const {
61 // By default, no analysis results are used, all are invalidated.
64 // releaseMemory() - This member can be implemented by a pass if it wants to
65 // be able to release its memory when it is no longer needed. The default
66 // behavior of passes is to hold onto memory for the entire duration of their
67 // lifetime (which is the entire compile time). For pipelined passes, this
68 // is not a big deal because that memory gets recycled every time the pass is
69 // invoked on another program unit. For IP passes, it is more important to
70 // free memory when it is unused.
72 // Optionally implement this function to release pass memory when it is no
75 virtual void releaseMemory() {}
77 // dumpPassStructure - Implement the -debug-passes=PassStructure option
78 virtual void dumpPassStructure(unsigned Offset = 0);
81 // getAnalysis<AnalysisType>() - This function is used by subclasses to get to
82 // the analysis information that they claim to use by overriding the
83 // getAnalysisUsage function.
85 template<typename AnalysisType>
86 AnalysisType &getAnalysis(AnalysisID AID = AnalysisType::ID) {
87 assert(Resolver && "Pass not resident in a PassManager object!");
88 return *(AnalysisType*)Resolver->getAnalysis(AID);
91 // getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses
92 // to get to the analysis information that might be around that needs to be
93 // updated. This is different than getAnalysis in that it can fail (ie the
94 // analysis results haven't been computed), so should only be used if you
95 // provide the capability to update an analysis that exists.
97 template<typename AnalysisType>
98 AnalysisType *getAnalysisToUpdate(AnalysisID AID = AnalysisType::ID) {
99 assert(Resolver && "Pass not resident in a PassManager object!");
100 return (AnalysisType*)Resolver->getAnalysisToUpdate(AID);
105 friend class PassManagerT<Module>;
106 friend class PassManagerT<Function>;
107 friend class PassManagerT<BasicBlock>;
108 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
112 //===----------------------------------------------------------------------===//
113 // FunctionPass class - This class is used to implement most global
114 // optimizations. Optimizations should subclass this class if they meet the
115 // following constraints:
117 // 1. Optimizations are organized globally, ie a function at a time
118 // 2. Optimizing a function does not cause the addition or removal of any
119 // functions in the module
121 struct FunctionPass : public Pass {
122 // doInitialization - Virtual method overridden by subclasses to do
123 // any neccesary per-module initialization.
125 virtual bool doInitialization(Module &M) { return false; }
127 // runOnFunction - Virtual method overriden by subclasses to do the
128 // per-function processing of the pass.
130 virtual bool runOnFunction(Function &F) = 0;
132 // doFinalization - Virtual method overriden by subclasses to do any post
133 // processing needed after all passes have run.
135 virtual bool doFinalization(Module &M) { return false; }
137 // run - On a module, we run this pass by initializing, ronOnFunction'ing once
138 // for every function in the module, then by finalizing.
140 virtual bool run(Module &M);
142 // run - On a function, we simply initialize, run the function, then finalize.
144 bool run(Function &F);
147 friend class PassManagerT<Module>;
148 friend class PassManagerT<Function>;
149 friend class PassManagerT<BasicBlock>;
150 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
151 virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU);
156 //===----------------------------------------------------------------------===//
157 // BasicBlockPass class - This class is used to implement most local
158 // optimizations. Optimizations should subclass this class if they
159 // meet the following constraints:
160 // 1. Optimizations are local, operating on either a basic block or
161 // instruction at a time.
162 // 2. Optimizations do not modify the CFG of the contained function, or any
163 // other basic block in the function.
164 // 3. Optimizations conform to all of the contstraints of FunctionPass's.
166 struct BasicBlockPass : public FunctionPass {
167 // runOnBasicBlock - Virtual method overriden by subclasses to do the
168 // per-basicblock processing of the pass.
170 virtual bool runOnBasicBlock(BasicBlock &BB) = 0;
172 // To run this pass on a function, we simply call runOnBasicBlock once for
175 virtual bool runOnFunction(Function &F);
177 // To run directly on the basic block, we initialize, runOnBasicBlock, then
180 bool run(BasicBlock &BB);
183 friend class PassManagerT<Function>;
184 friend class PassManagerT<BasicBlock>;
185 virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU);
186 virtual void addToPassManager(PassManagerT<BasicBlock> *PM,AnalysisUsage &AU);
190 // CreatePass - Helper template to invoke the constructor for the AnalysisID
191 // class. Note that this should be a template internal to AnalysisID, but
192 // GCC 2.95.3 crashes if we do that, doh.
194 template<class AnalysisType>
195 static Pass *CreatePass(AnalysisID ID) { return new AnalysisType(ID); }
197 //===----------------------------------------------------------------------===//
198 // AnalysisID - This class is used to uniquely identify an analysis pass that
199 // is referenced by a transformation.
202 static unsigned NextID; // Next ID # to deal out...
203 unsigned ID; // Unique ID for this analysis
204 Pass *(*Constructor)(AnalysisID); // Constructor to return the Analysis
206 AnalysisID(); // Disable default ctor
207 AnalysisID(unsigned id, Pass *(*Ct)(AnalysisID)) : ID(id), Constructor(Ct) {}
209 // create - the only way to define a new AnalysisID. This static method is
210 // supposed to be used to define the class static AnalysisID's that are
211 // provided by analysis passes. In the implementation (.cpp) file for the
212 // class, there should be a line that looks like this (using CallGraph as an
215 // AnalysisID CallGraph::ID(AnalysisID::create<CallGraph>());
217 template<class AnalysisType>
218 static AnalysisID create() {
219 return AnalysisID(NextID++, CreatePass<AnalysisType>);
222 // Special Copy Constructor - This is how analysis passes declare that they
223 // only depend on the CFG of the function they are working on, so they are not
224 // invalidated by other passes that do not modify the CFG. This should be
226 // AnalysisID DominatorSet::ID(AnalysisID::create<DominatorSet>(), true);
228 AnalysisID(const AnalysisID &AID, bool DependsOnlyOnCFG = false);
231 inline Pass *createPass() const { return Constructor(*this); }
233 inline bool operator==(const AnalysisID &A) const {
236 inline bool operator!=(const AnalysisID &A) const {
239 inline bool operator<(const AnalysisID &A) const {
244 //===----------------------------------------------------------------------===//
245 // AnalysisUsage - Represent the analysis usage information of a pass. This
246 // tracks analyses that the pass REQUIRES (must available when the pass runs),
247 // and analyses that the pass PRESERVES (the pass does not invalidate the
248 // results of these analyses). This information is provided by a pass to the
249 // Pass infrastructure through the getAnalysisUsage virtual function.
251 class AnalysisUsage {
252 // Sets of analyses required and preserved by a pass
253 std::vector<AnalysisID> Required, Preserved, Provided;
256 AnalysisUsage() : PreservesAll(false) {}
258 // addRequires - Add the specified ID to the required set of the usage info
261 AnalysisUsage &addRequired(AnalysisID ID) {
262 Required.push_back(ID);
266 // addPreserves - Add the specified ID to the set of analyses preserved by
269 AnalysisUsage &addPreserved(AnalysisID ID) {
270 Preserved.push_back(ID);
274 void addProvided(AnalysisID ID) {
275 Provided.push_back(ID);
278 // PreservesAll - Set by analyses that do not transform their input at all
279 void setPreservesAll() { PreservesAll = true; }
280 bool preservesAll() const { return PreservesAll; }
282 // preservesCFG - This function should be called to by the pass, iff they do
285 // 1. Add or remove basic blocks from the function
286 // 2. Modify terminator instructions in any way.
288 // This function annotates the AnalysisUsage info object to say that analyses
289 // that only depend on the CFG are preserved by this pass.
293 const std::vector<AnalysisID> &getRequiredSet() const { return Required; }
294 const std::vector<AnalysisID> &getPreservedSet() const { return Preserved; }
295 const std::vector<AnalysisID> &getProvidedSet() const { return Provided; }
300 //===----------------------------------------------------------------------===//
301 // AnalysisResolver - Simple interface implemented by PassManagers objects that
302 // is used to pull analysis information out of them.
304 struct AnalysisResolver {
305 virtual Pass *getAnalysisOrNullUp(AnalysisID ID) const = 0;
306 virtual Pass *getAnalysisOrNullDown(AnalysisID ID) const = 0;
307 Pass *getAnalysis(AnalysisID ID) {
308 Pass *Result = getAnalysisOrNullUp(ID);
309 assert(Result && "Pass has an incorrect analysis uses set!");
313 // getAnalysisToUpdate - Return an analysis result or null if it doesn't exist
314 Pass *getAnalysisToUpdate(AnalysisID ID) {
315 Pass *Result = getAnalysisOrNullUp(ID);
319 virtual unsigned getDepth() const = 0;
321 virtual void markPassUsed(AnalysisID P, Pass *User) = 0;
323 void startPass(Pass *P) {}
324 void endPass(Pass *P) {}
326 void setAnalysisResolver(Pass *P, AnalysisResolver *AR);