1 //===- llvm/Support/InstVisitor.h - Define instruction visitors --*- C++ -*--=//
3 // This template class is used to define instruction visitors in a typesafe
4 // manner without having to use lots of casts and a big switch statement (in
5 // your code that is). The win here is that if instructions are added in the
6 // future, they will be added to the InstVisitor<T> class, allowing you to
7 // automatically support them (if you handle on of their superclasses).
9 // Note that this library is specifically designed as a template to avoid
10 // virtual function call overhead. Defining and using an InstVisitor is just as
11 // efficient as having your own switch statement over the instruction opcode.
14 // You define InstVisitors from inheriting from the InstVisitor base class
15 // and "overriding" functions in your class. I say "overriding" because this
16 // class is defined in terms of statically resolved overloading, not virtual
17 // functions. As an example, here is a visitor that counts the number of malloc
18 // instructions processed:
20 // // Declare the class. Note that we derive from InstVisitor instantiated
21 // // with _our new subclasses_ type.
23 // struct CountMallocVisitor : public InstVisitor<CountMallocVisitor> {
25 // CountMallocVisitor() : Count(0) {}
27 // void visitMallocInst(MallocInst *MI) { ++Count; }
30 // And this class would be used like this:
31 // CountMallocVistor CMV;
32 // CMV.visit(function);
33 // NumMallocs = CMV.Count;
35 // Returning a value from the visitation function:
36 // The InstVisitor class takes an optional second template argument that
37 // specifies what type the instruction visitation functions should return. If
38 // you specify this, you *MUST* provide an implementation of visitInstruction
41 //===----------------------------------------------------------------------===//
43 #ifndef LLVM_SUPPORT_INSTVISITOR_H
44 #define LLVM_SUPPORT_INSTVISITOR_H
46 #include "llvm/Instruction.h"
49 // We operate on opaque instruction classes, so forward declare all instruction
52 #define HANDLE_INST(NUM, OPCODE, CLASS) class CLASS;
53 #include "llvm/Instruction.def"
55 // Forward declare the intermediate types...
56 class TerminatorInst; class BinaryOperator;
60 #define DELEGATE(CLASS_TO_VISIT) \
61 return ((SubClass*)this)->visit##CLASS_TO_VISIT((CLASS_TO_VISIT&)I)
64 template<typename SubClass, typename RetTy=void>
66 virtual ~InstVisitor() {} // We are meant to be derived from
68 //===--------------------------------------------------------------------===//
69 // Interface code - This is the public interface of the InstVisitor that you
70 // use to visit instructions...
73 // Generic visit method - Allow visitation to all instructions in a range
74 template<class Iterator>
75 void visit(Iterator Start, Iterator End) {
77 ((SubClass*)this)->visit(*Start++);
80 // Define visitors for modules, functions and basic blocks...
82 void visit(Module &M) {
83 ((SubClass*)this)->visitModule(M);
84 visit(M.begin(), M.end());
86 void visit(Function &F) {
87 ((SubClass*)this)->visitFunction(F);
88 visit(F.begin(), F.end());
90 void visit(BasicBlock &BB) {
91 ((SubClass*)this)->visitBasicBlock(BB);
92 visit(BB.begin(), BB.end());
95 // Forwarding functions so that the user can visit with pointers AND refs.
96 void visit(Module *M) { visit(*M); }
97 void visit(Function *F) { visit(*F); }
98 void visit(BasicBlock *BB) { visit(*BB); }
99 RetTy visit(Instruction *I) { return visit(*I); }
101 // visit - Finally, code to visit an instruction...
103 RetTy visit(Instruction &I) {
104 switch (I.getOpcode()) {
105 default: assert(0 && "Unknown instruction type encountered!");
107 // Build the switch statement using the Instruction.def file...
108 #define HANDLE_INST(NUM, OPCODE, CLASS) \
109 case Instruction::OPCODE:return ((SubClass*)this)->visit##OPCODE((CLASS&)I);
110 #include "llvm/Instruction.def"
114 //===--------------------------------------------------------------------===//
115 // Visitation functions... these functions provide default fallbacks in case
116 // the user does not specify what to do for a particular instruction type.
117 // The default behavior is to generalize the instruction type to its subtype
118 // and try visiting the subtype. All of this should be inlined perfectly,
119 // because there are no virtual functions to get in the way.
122 // When visiting a module, function or basic block directly, these methods get
123 // called to indicate when transitioning into a new unit.
125 void visitModule (Module &M) {}
126 void visitFunction (Function &F) {}
127 void visitBasicBlock(BasicBlock &BB) {}
130 // Define instruction specific visitor functions that can be overridden to
131 // handle SPECIFIC instructions. These functions automatically define
132 // visitMul to proxy to visitBinaryOperator for instance in case the user does
133 // not need this generality.
135 // The one problem case we have to handle here though is that the PHINode
136 // class and opcode name are the exact same. Because of this, we cannot
137 // define visitPHINode (the inst version) to forward to visitPHINode (the
138 // generic version) without multiply defined symbols and recursion. To handle
139 // this, we do not autoexpand "Other" instructions, we do it manually.
141 #define HANDLE_INST(NUM, OPCODE, CLASS) \
142 RetTy visit##OPCODE(CLASS &I) { DELEGATE(CLASS); }
143 #define HANDLE_OTHER_INST(NUM, OPCODE, CLASS) // Ignore "other" instructions
144 #include "llvm/Instruction.def"
146 // Implement all "other" instructions, except for PHINode
147 RetTy visitCast(CastInst &I) { DELEGATE(CastInst); }
148 RetTy visitCall(CallInst &I) { DELEGATE(CallInst); }
149 RetTy visitShr(ShiftInst &I) { DELEGATE(ShiftInst); }
150 RetTy visitShl(ShiftInst &I) { DELEGATE(ShiftInst); }
151 RetTy visitUserOp1(Instruction &I) { DELEGATE(Instruction); }
152 RetTy visitUserOp2(Instruction &I) { DELEGATE(Instruction); }
155 // Specific Instruction type classes... note that all of the casts are
156 // neccesary because we use the instruction classes as opaque types...
158 RetTy visitReturnInst(ReturnInst &I) { DELEGATE(TerminatorInst);}
159 RetTy visitBranchInst(BranchInst &I) { DELEGATE(TerminatorInst);}
160 RetTy visitSwitchInst(SwitchInst &I) { DELEGATE(TerminatorInst);}
161 RetTy visitInvokeInst(InvokeInst &I) { DELEGATE(TerminatorInst);}
162 RetTy visitGenericBinaryInst(GenericBinaryInst &I){ DELEGATE(BinaryOperator);}
163 RetTy visitSetCondInst(SetCondInst &I) { DELEGATE(BinaryOperator);}
164 RetTy visitMallocInst(MallocInst &I) { DELEGATE(AllocationInst);}
165 RetTy visitAllocaInst(AllocaInst &I) { DELEGATE(AllocationInst);}
166 RetTy visitFreeInst(FreeInst &I) { DELEGATE(Instruction); }
167 RetTy visitLoadInst(LoadInst &I) { DELEGATE(Instruction); }
168 RetTy visitStoreInst(StoreInst &I) { DELEGATE(Instruction); }
169 RetTy visitGetElementPtrInst(GetElementPtrInst &I){ DELEGATE(Instruction); }
170 RetTy visitPHINode(PHINode &I) { DELEGATE(Instruction); }
171 RetTy visitCastInst(CastInst &I) { DELEGATE(Instruction); }
172 RetTy visitCallInst(CallInst &I) { DELEGATE(Instruction); }
173 RetTy visitShiftInst(ShiftInst &I) { DELEGATE(Instruction); }
175 // Next level propogators... if the user does not overload a specific
176 // instruction type, they can overload one of these to get the whole class
177 // of instructions...
179 RetTy visitTerminatorInst(TerminatorInst &I) { DELEGATE(Instruction); }
180 RetTy visitBinaryOperator(BinaryOperator &I) { DELEGATE(Instruction); }
181 RetTy visitAllocationInst(AllocationInst &I) { DELEGATE(Instruction); }
183 // If the user wants a 'default' case, they can choose to override this
184 // function. If this function is not overloaded in the users subclass, then
185 // this instruction just gets ignored.
187 // Note that you MUST override this function if your return type is not void.
189 void visitInstruction(Instruction &I) {} // Ignore unhandled instructions