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 //===----------------------------------------------------------------------===//
34 template<class UnitType> class PassManagerT;
35 struct AnalysisResolver;
37 // AnalysisID - Use the PassInfo to identify a pass...
38 typedef const PassInfo* AnalysisID;
41 //===----------------------------------------------------------------------===//
42 // Pass interface - Implemented by all 'passes'. Subclass this if you are an
43 // interprocedural optimization or you do not fit into any of the more
44 // constrained passes described below.
47 friend class AnalysisResolver;
48 AnalysisResolver *Resolver; // AnalysisResolver this pass is owned by...
50 Pass(AnalysisResolver *AR = 0) : Resolver(AR) {}
51 virtual ~Pass() {} // Destructor is virtual so we can be subclassed
53 // getPassName - Return a nice clean name for a pass. This should be
54 // overloaded by the pass, but if it is not, C++ RTTI will be consulted to get
55 // a SOMEWHAT intelligable name for the pass.
57 virtual const char *getPassName() const;
59 // getPassInfo - Return the PassInfo data structure that corresponds to this
61 const PassInfo *getPassInfo() const;
63 // run - Run this pass, returning true if a modification was made to the
64 // module argument. This should be implemented by all concrete subclasses.
66 virtual bool run(Module &M) = 0;
68 // print - Print out the internal state of the pass. This is called by
69 // Analyze to print out the contents of an analysis. Otherwise it is not
70 // neccesary to implement this method. Beware that the module pointer MAY be
71 // null. This automatically forwards to a virtual function that does not
72 // provide the Module* in case the analysis doesn't need it it can just be
75 virtual void print(std::ostream &O, const Module *M) const { print(O); }
76 virtual void print(std::ostream &O) const;
77 void dump() const; // dump - call print(std::cerr, 0);
80 // getAnalysisUsage - This function should be overriden by passes that need
81 // analysis information to do their job. If a pass specifies that it uses a
82 // particular analysis result to this function, it can then use the
83 // getAnalysis<AnalysisType>() function, below.
85 virtual void getAnalysisUsage(AnalysisUsage &Info) const {
86 // By default, no analysis results are used, all are invalidated.
89 // releaseMemory() - This member can be implemented by a pass if it wants to
90 // be able to release its memory when it is no longer needed. The default
91 // behavior of passes is to hold onto memory for the entire duration of their
92 // lifetime (which is the entire compile time). For pipelined passes, this
93 // is not a big deal because that memory gets recycled every time the pass is
94 // invoked on another program unit. For IP passes, it is more important to
95 // free memory when it is unused.
97 // Optionally implement this function to release pass memory when it is no
100 virtual void releaseMemory() {}
102 // dumpPassStructure - Implement the -debug-passes=PassStructure option
103 virtual void dumpPassStructure(unsigned Offset = 0);
106 // getAnalysis<AnalysisType>() - This function is used by subclasses to get to
107 // the analysis information that they claim to use by overriding the
108 // getAnalysisUsage function.
110 template<typename AnalysisType>
111 AnalysisType &getAnalysis(AnalysisID AID = AnalysisType::ID) {
112 assert(Resolver && "Pass not resident in a PassManager object!");
113 return *(AnalysisType*)Resolver->getAnalysis(AID);
116 // getAnalysisToUpdate<AnalysisType>() - This function is used by subclasses
117 // to get to the analysis information that might be around that needs to be
118 // updated. This is different than getAnalysis in that it can fail (ie the
119 // analysis results haven't been computed), so should only be used if you
120 // provide the capability to update an analysis that exists.
122 template<typename AnalysisType>
123 AnalysisType *getAnalysisToUpdate(AnalysisID AID = AnalysisType::ID) {
124 assert(Resolver && "Pass not resident in a PassManager object!");
125 return (AnalysisType*)Resolver->getAnalysisToUpdate(AID);
130 friend class PassManagerT<Module>;
131 friend class PassManagerT<Function>;
132 friend class PassManagerT<BasicBlock>;
133 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
136 inline std::ostream &operator<<(std::ostream &OS, const Pass &P) {
137 P.print(OS, 0); return OS;
140 //===----------------------------------------------------------------------===//
141 // FunctionPass class - This class is used to implement most global
142 // optimizations. Optimizations should subclass this class if they meet the
143 // following constraints:
145 // 1. Optimizations are organized globally, ie a function at a time
146 // 2. Optimizing a function does not cause the addition or removal of any
147 // functions in the module
149 struct FunctionPass : public Pass {
150 // doInitialization - Virtual method overridden by subclasses to do
151 // any neccesary per-module initialization.
153 virtual bool doInitialization(Module &M) { return false; }
155 // runOnFunction - Virtual method overriden by subclasses to do the
156 // per-function processing of the pass.
158 virtual bool runOnFunction(Function &F) = 0;
160 // doFinalization - Virtual method overriden by subclasses to do any post
161 // processing needed after all passes have run.
163 virtual bool doFinalization(Module &M) { return false; }
165 // run - On a module, we run this pass by initializing, ronOnFunction'ing once
166 // for every function in the module, then by finalizing.
168 virtual bool run(Module &M);
170 // run - On a function, we simply initialize, run the function, then finalize.
172 bool run(Function &F);
175 friend class PassManagerT<Module>;
176 friend class PassManagerT<Function>;
177 friend class PassManagerT<BasicBlock>;
178 virtual void addToPassManager(PassManagerT<Module> *PM, AnalysisUsage &AU);
179 virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU);
184 //===----------------------------------------------------------------------===//
185 // BasicBlockPass class - This class is used to implement most local
186 // optimizations. Optimizations should subclass this class if they
187 // meet the following constraints:
188 // 1. Optimizations are local, operating on either a basic block or
189 // instruction at a time.
190 // 2. Optimizations do not modify the CFG of the contained function, or any
191 // other basic block in the function.
192 // 3. Optimizations conform to all of the contstraints of FunctionPass's.
194 struct BasicBlockPass : public FunctionPass {
195 // runOnBasicBlock - Virtual method overriden by subclasses to do the
196 // per-basicblock processing of the pass.
198 virtual bool runOnBasicBlock(BasicBlock &BB) = 0;
200 // To run this pass on a function, we simply call runOnBasicBlock once for
203 virtual bool runOnFunction(Function &F);
205 // To run directly on the basic block, we initialize, runOnBasicBlock, then
208 bool run(BasicBlock &BB);
211 friend class PassManagerT<Function>;
212 friend class PassManagerT<BasicBlock>;
213 virtual void addToPassManager(PassManagerT<Function> *PM, AnalysisUsage &AU);
214 virtual void addToPassManager(PassManagerT<BasicBlock> *PM,AnalysisUsage &AU);
217 // Include support files that contain important APIs commonly used by Passes,
218 // but that we want to seperate out to make it easier to read the header files.
220 #include "llvm/PassSupport.h"
221 #include "llvm/PassAnalysisSupport.h"