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"
50 // We operate on opaque instruction classes, so forward declare all instruction
53 #define HANDLE_INST(NUM, OPCODE, CLASS) class CLASS;
54 #include "llvm/Instruction.def"
56 // Forward declare the intermediate types...
57 class TerminatorInst; class BinaryOperator;
61 #define DELEGATE(CLASS_TO_VISIT) \
62 return ((SubClass*)this)->visit##CLASS_TO_VISIT((CLASS_TO_VISIT&)I)
65 template<typename SubClass, typename RetTy=void>
67 virtual ~InstVisitor() {} // We are meant to be derived from
69 //===--------------------------------------------------------------------===//
70 // Interface code - This is the public interface of the InstVisitor that you
71 // use to visit instructions...
74 // Generic visit method - Allow visitation to all instructions in a range
75 template<class Iterator>
76 void visit(Iterator Start, Iterator End) {
78 ((SubClass*)this)->visit(*Start++);
81 // Define visitors for functions and basic blocks...
83 void visit(Function &F) {
84 ((SubClass*)this)->visitFunction(F);
85 visit(F.begin(), F.end());
87 void visit(BasicBlock &BB) {
88 ((SubClass*)this)->visitBasicBlock(BB);
89 visit(BB.begin(), BB.end());
92 // Forwarding functions so that the user can visit with pointers AND refs.
93 void visit(Module *M) { visit(*M); }
94 void visit(Function *F) { visit(*F); }
95 void visit(BasicBlock *BB) { visit(*BB); }
96 RetTy visit(Instruction *I) { return visit(*I); }
98 // visit - Finally, code to visit an instruction...
100 RetTy visit(Instruction &I) {
101 switch (I.getOpcode()) {
102 default: assert(0 && "Unknown instruction type encountered!");
104 // Build the switch statement using the Instruction.def file...
105 #define HANDLE_INST(NUM, OPCODE, CLASS) \
106 case Instruction::OPCODE:return ((SubClass*)this)->visit##OPCODE((CLASS&)I);
107 #include "llvm/Instruction.def"
111 //===--------------------------------------------------------------------===//
112 // Visitation functions... these functions provide default fallbacks in case
113 // the user does not specify what to do for a particular instruction type.
114 // The default behavior is to generalize the instruction type to its subtype
115 // and try visiting the subtype. All of this should be inlined perfectly,
116 // because there are no virtual functions to get in the way.
119 // When visiting a module, function or basic block directly, these methods get
120 // called to indicate when transitioning into a new unit.
122 void visitFunction (Function &F) {}
123 void visitBasicBlock(BasicBlock &BB) {}
126 // Define instruction specific visitor functions that can be overridden to
127 // handle SPECIFIC instructions. These functions automatically define
128 // visitMul to proxy to visitBinaryOperator for instance in case the user does
129 // not need this generality.
131 // The one problem case we have to handle here though is that the PHINode
132 // class and opcode name are the exact same. Because of this, we cannot
133 // define visitPHINode (the inst version) to forward to visitPHINode (the
134 // generic version) without multiply defined symbols and recursion. To handle
135 // this, we do not autoexpand "Other" instructions, we do it manually.
137 #define HANDLE_INST(NUM, OPCODE, CLASS) \
138 RetTy visit##OPCODE(CLASS &I) { DELEGATE(CLASS); }
139 #include "llvm/Instruction.def"
141 // Specific Instruction type classes... note that all of the casts are
142 // necessary because we use the instruction classes as opaque types...
144 RetTy visitReturnInst(ReturnInst &I) { DELEGATE(TerminatorInst);}
145 RetTy visitBranchInst(BranchInst &I) { DELEGATE(TerminatorInst);}
146 RetTy visitSwitchInst(SwitchInst &I) { DELEGATE(TerminatorInst);}
147 RetTy visitInvokeInst(InvokeInst &I) { DELEGATE(TerminatorInst);}
148 RetTy visitUnwindInst(UnwindInst &I) { DELEGATE(TerminatorInst);}
149 RetTy visitSetCondInst(SetCondInst &I) { DELEGATE(BinaryOperator);}
150 RetTy visitMallocInst(MallocInst &I) { DELEGATE(AllocationInst);}
151 RetTy visitAllocaInst(AllocaInst &I) { DELEGATE(AllocationInst);}
152 RetTy visitFreeInst(FreeInst &I) { DELEGATE(Instruction); }
153 RetTy visitLoadInst(LoadInst &I) { DELEGATE(Instruction); }
154 RetTy visitStoreInst(StoreInst &I) { DELEGATE(Instruction); }
155 RetTy visitGetElementPtrInst(GetElementPtrInst &I){ DELEGATE(Instruction); }
156 RetTy visitPHINode(PHINode &I) { DELEGATE(Instruction); }
157 RetTy visitCastInst(CastInst &I) { DELEGATE(Instruction); }
158 RetTy visitCallInst(CallInst &I) { DELEGATE(Instruction); }
159 RetTy visitShiftInst(ShiftInst &I) { DELEGATE(Instruction); }
160 RetTy visitVANextInst(VANextInst &I) { DELEGATE(Instruction); }
161 RetTy visitVAArgInst(VAArgInst &I) { DELEGATE(Instruction); }
163 // Next level propagators... if the user does not overload a specific
164 // instruction type, they can overload one of these to get the whole class
165 // of instructions...
167 RetTy visitTerminatorInst(TerminatorInst &I) { DELEGATE(Instruction); }
168 RetTy visitBinaryOperator(BinaryOperator &I) { DELEGATE(Instruction); }
169 RetTy visitAllocationInst(AllocationInst &I) { DELEGATE(Instruction); }
171 // If the user wants a 'default' case, they can choose to override this
172 // function. If this function is not overloaded in the users subclass, then
173 // this instruction just gets ignored.
175 // Note that you MUST override this function if your return type is not void.
177 void visitInstruction(Instruction &I) {} // Ignore unhandled instructions