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"
48 // We operate on opaque instruction classes, so forward declare all instruction
51 #define HANDLE_INST(NUM, OPCODE, CLASS) class CLASS;
52 #include "llvm/Instruction.def"
54 // Forward declare the intermediate types...
55 class TerminatorInst; class BinaryOperator;
56 class AllocationInst; class MemAccessInst;
59 #define DELEGATE(CLASS_TO_VISIT) \
60 return ((SubClass*)this)->visit##CLASS_TO_VISIT((CLASS_TO_VISIT&)I)
63 template<typename SubClass, typename RetTy=void>
65 virtual ~InstVisitor() {} // We are meant to be derived from
67 //===--------------------------------------------------------------------===//
68 // Interface code - This is the public interface of the InstVisitor that you
69 // use to visit instructions...
72 // Generic visit method - Allow visitation to all instructions in a range
73 template<class Iterator>
74 void visit(Iterator Start, Iterator End) {
76 ((SubClass*)this)->visit(*Start++);
79 // Define visitors for modules, functions and basic blocks...
81 void visit(Module &M) {
82 ((SubClass*)this)->visitModule(M);
83 visit(M.begin(), M.end());
85 void visit(Function &F) {
86 ((SubClass*)this)->visitFunction(F);
87 visit(F.begin(), F.end());
89 void visit(BasicBlock &BB) {
90 ((SubClass*)this)->visitBasicBlock(BB);
91 visit(BB.begin(), BB.end());
94 // Forwarding functions so that the user can visit with pointers AND refs.
95 void visit(Module *M) { visit(*M); }
96 void visit(Function *F) { visit(*F); }
97 void visit(BasicBlock *BB) { visit(*BB); }
98 RetTy visit(Instruction *I) { return visit(*I); }
100 // visit - Finally, code to visit an instruction...
102 RetTy visit(Instruction &I) {
103 switch (I.getOpcode()) {
104 default: assert(0 && "Unknown instruction type encountered!");
106 // Build the switch statement using the Instruction.def file...
107 #define HANDLE_INST(NUM, OPCODE, CLASS) \
108 case Instruction::OPCODE:return ((SubClass*)this)->visit##OPCODE((CLASS&)I);
109 #include "llvm/Instruction.def"
113 //===--------------------------------------------------------------------===//
114 // Visitation functions... these functions provide default fallbacks in case
115 // the user does not specify what to do for a particular instruction type.
116 // The default behavior is to generalize the instruction type to its subtype
117 // and try visiting the subtype. All of this should be inlined perfectly,
118 // because there are no virtual functions to get in the way.
121 // When visiting a module, function or basic block directly, these methods get
122 // called to indicate when transitioning into a new unit.
124 void visitModule (Module &M) {}
125 void visitFunction (Function &F) {}
126 void visitBasicBlock(BasicBlock &BB) {}
129 // Define instruction specific visitor functions that can be overridden to
130 // handle SPECIFIC instructions. These functions automatically define
131 // visitMul to proxy to visitBinaryOperator for instance in case the user does
132 // not need this generality.
134 // The one problem case we have to handle here though is that the PHINode
135 // class and opcode name are the exact same. Because of this, we cannot
136 // define visitPHINode (the inst version) to forward to visitPHINode (the
137 // generic version) without multiply defined symbols and recursion. To handle
138 // this, we do not autoexpand "Other" instructions, we do it manually.
140 #define HANDLE_INST(NUM, OPCODE, CLASS) \
141 RetTy visit##OPCODE(CLASS &I) { DELEGATE(CLASS); }
142 #define HANDLE_OTHER_INST(NUM, OPCODE, CLASS) // Ignore "other" instructions
143 #include "llvm/Instruction.def"
145 // Implement all "other" instructions, except for PHINode
146 RetTy visitCast(CastInst &I) { DELEGATE(CastInst); }
147 RetTy visitCall(CallInst &I) { DELEGATE(CallInst); }
148 RetTy visitShr(ShiftInst &I) { DELEGATE(ShiftInst); }
149 RetTy visitShl(ShiftInst &I) { DELEGATE(ShiftInst); }
150 RetTy visitUserOp1(Instruction &I) { DELEGATE(Instruction); }
151 RetTy visitUserOp2(Instruction &I) { DELEGATE(Instruction); }
154 // Specific Instruction type classes... note that all of the casts are
155 // neccesary because we use the instruction classes as opaque types...
157 RetTy visitReturnInst(ReturnInst &I) { DELEGATE(TerminatorInst);}
158 RetTy visitBranchInst(BranchInst &I) { DELEGATE(TerminatorInst);}
159 RetTy visitSwitchInst(SwitchInst &I) { DELEGATE(TerminatorInst);}
160 RetTy visitInvokeInst(InvokeInst &I) { DELEGATE(TerminatorInst);}
161 RetTy visitGenericBinaryInst(GenericBinaryInst &I){ DELEGATE(BinaryOperator);}
162 RetTy visitSetCondInst(SetCondInst &I) { DELEGATE(BinaryOperator);}
163 RetTy visitMallocInst(MallocInst &I) { DELEGATE(AllocationInst);}
164 RetTy visitAllocaInst(AllocaInst &I) { DELEGATE(AllocationInst);}
165 RetTy visitFreeInst(FreeInst &I) { DELEGATE(Instruction); }
166 RetTy visitLoadInst(LoadInst &I) { DELEGATE(MemAccessInst); }
167 RetTy visitStoreInst(StoreInst &I) { DELEGATE(MemAccessInst); }
168 RetTy visitGetElementPtrInst(GetElementPtrInst &I){ DELEGATE(MemAccessInst); }
169 RetTy visitPHINode(PHINode &I) { DELEGATE(Instruction); }
170 RetTy visitCastInst(CastInst &I) { DELEGATE(Instruction); }
171 RetTy visitCallInst(CallInst &I) { DELEGATE(Instruction); }
172 RetTy visitShiftInst(ShiftInst &I) { DELEGATE(Instruction); }
174 // Next level propogators... if the user does not overload a specific
175 // instruction type, they can overload one of these to get the whole class
176 // of instructions...
178 RetTy visitTerminatorInst(TerminatorInst &I) { DELEGATE(Instruction); }
179 RetTy visitBinaryOperator(BinaryOperator &I) { DELEGATE(Instruction); }
180 RetTy visitAllocationInst(AllocationInst &I) { DELEGATE(Instruction); }
181 RetTy visitMemAccessInst (MemAccessInst &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