1 //===- llvm/Support/InstVisitor.h - Define instruction visitors -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This template class is used to define instruction visitors in a typesafe
11 // manner without having to use lots of casts and a big switch statement (in
12 // your code that is). The win here is that if instructions are added in the
13 // future, they will be added to the InstVisitor<T> class, allowing you to
14 // automatically support them (if you handle on of their superclasses).
16 // Note that this library is specifically designed as a template to avoid
17 // virtual function call overhead. Defining and using an InstVisitor is just as
18 // efficient as having your own switch statement over the instruction opcode.
21 // You define InstVisitors from inheriting from the InstVisitor base class
22 // and "overriding" functions in your class. I say "overriding" because this
23 // class is defined in terms of statically resolved overloading, not virtual
24 // functions. As an example, here is a visitor that counts the number of malloc
25 // instructions processed:
27 // // Declare the class. Note that we derive from InstVisitor instantiated
28 // // with _our new subclasses_ type.
30 // struct CountMallocVisitor : public InstVisitor<CountMallocVisitor> {
32 // CountMallocVisitor() : Count(0) {}
34 // void visitMallocInst(MallocInst *MI) { ++Count; }
37 // And this class would be used like this:
38 // CountMallocVistor CMV;
39 // CMV.visit(function);
40 // NumMallocs = CMV.Count;
42 // Returning a value from the visitation function:
43 // The InstVisitor class takes an optional second template argument that
44 // specifies what type the instruction visitation functions should return. If
45 // you specify this, you *MUST* provide an implementation of visitInstruction
48 //===----------------------------------------------------------------------===//
50 #ifndef LLVM_SUPPORT_INSTVISITOR_H
51 #define LLVM_SUPPORT_INSTVISITOR_H
53 #include "llvm/Function.h"
54 #include "llvm/Module.h"
58 // We operate on opaque instruction classes, so forward declare all instruction
61 #define HANDLE_INST(NUM, OPCODE, CLASS) class CLASS;
62 #include "llvm/Instruction.def"
64 // Forward declare the intermediate types...
65 class TerminatorInst; class BinaryOperator;
68 #define DELEGATE(CLASS_TO_VISIT) \
69 return ((SubClass*)this)->visit##CLASS_TO_VISIT((CLASS_TO_VISIT&)I)
72 template<typename SubClass, typename RetTy=void>
74 //===--------------------------------------------------------------------===//
75 // Interface code - This is the public interface of the InstVisitor that you
76 // use to visit instructions...
79 // Generic visit method - Allow visitation to all instructions in a range
80 template<class Iterator>
81 void visit(Iterator Start, Iterator End) {
83 ((SubClass*)this)->visit(*Start++);
86 // Define visitors for functions and basic blocks...
88 void visit(Module &M) {
89 ((SubClass*)this)->visitModule(M);
90 visit(M.begin(), M.end());
92 void visit(Function &F) {
93 ((SubClass*)this)->visitFunction(F);
94 visit(F.begin(), F.end());
96 void visit(BasicBlock &BB) {
97 ((SubClass*)this)->visitBasicBlock(BB);
98 visit(BB.begin(), BB.end());
101 // Forwarding functions so that the user can visit with pointers AND refs.
102 void visit(Module *M) { visit(*M); }
103 void visit(Function *F) { visit(*F); }
104 void visit(BasicBlock *BB) { visit(*BB); }
105 RetTy visit(Instruction *I) { return visit(*I); }
107 // visit - Finally, code to visit an instruction...
109 RetTy visit(Instruction &I) {
110 switch (I.getOpcode()) {
111 default: assert(0 && "Unknown instruction type encountered!");
113 // Build the switch statement using the Instruction.def file...
114 #define HANDLE_INST(NUM, OPCODE, CLASS) \
115 case Instruction::OPCODE:return ((SubClass*)this)->visit##OPCODE((CLASS&)I);
116 #include "llvm/Instruction.def"
120 //===--------------------------------------------------------------------===//
121 // Visitation functions... these functions provide default fallbacks in case
122 // the user does not specify what to do for a particular instruction type.
123 // The default behavior is to generalize the instruction type to its subtype
124 // and try visiting the subtype. All of this should be inlined perfectly,
125 // because there are no virtual functions to get in the way.
128 // When visiting a module, function or basic block directly, these methods get
129 // called to indicate when transitioning into a new unit.
131 void visitModule (Module &M) {}
132 void visitFunction (Function &F) {}
133 void visitBasicBlock(BasicBlock &BB) {}
136 // Define instruction specific visitor functions that can be overridden to
137 // handle SPECIFIC instructions. These functions automatically define
138 // visitMul to proxy to visitBinaryOperator for instance in case the user does
139 // not need this generality.
141 // The one problem case we have to handle here though is that the PHINode
142 // class and opcode name are the exact same. Because of this, we cannot
143 // define visitPHINode (the inst version) to forward to visitPHINode (the
144 // generic version) without multiply defined symbols and recursion. To handle
145 // this, we do not autoexpand "Other" instructions, we do it manually.
147 #define HANDLE_INST(NUM, OPCODE, CLASS) \
148 RetTy visit##OPCODE(CLASS &I) { DELEGATE(CLASS); }
149 #include "llvm/Instruction.def"
151 // Specific Instruction type classes... note that all of the casts are
152 // necessary because we use the instruction classes as opaque types...
154 RetTy visitReturnInst(ReturnInst &I) { DELEGATE(TerminatorInst);}
155 RetTy visitBranchInst(BranchInst &I) { DELEGATE(TerminatorInst);}
156 RetTy visitSwitchInst(SwitchInst &I) { DELEGATE(TerminatorInst);}
157 RetTy visitInvokeInst(InvokeInst &I) { DELEGATE(TerminatorInst);}
158 RetTy visitUnwindInst(UnwindInst &I) { DELEGATE(TerminatorInst);}
159 RetTy visitSetCondInst(SetCondInst &I) { DELEGATE(BinaryOperator);}
160 RetTy visitMallocInst(MallocInst &I) { DELEGATE(AllocationInst);}
161 RetTy visitAllocaInst(AllocaInst &I) { DELEGATE(AllocationInst);}
162 RetTy visitFreeInst(FreeInst &I) { DELEGATE(Instruction); }
163 RetTy visitLoadInst(LoadInst &I) { DELEGATE(Instruction); }
164 RetTy visitStoreInst(StoreInst &I) { DELEGATE(Instruction); }
165 RetTy visitGetElementPtrInst(GetElementPtrInst &I){ DELEGATE(Instruction); }
166 RetTy visitPHINode(PHINode &I) { DELEGATE(Instruction); }
167 RetTy visitCastInst(CastInst &I) { DELEGATE(Instruction); }
168 RetTy visitSelectInst(SelectInst &I) { DELEGATE(Instruction); }
169 RetTy visitCallInst(CallInst &I) { DELEGATE(Instruction); }
170 RetTy visitShiftInst(ShiftInst &I) { DELEGATE(Instruction); }
171 RetTy visitVANextInst(VANextInst &I) { DELEGATE(Instruction); }
172 RetTy visitVAArgInst(VAArgInst &I) { DELEGATE(Instruction); }
174 // Next level propagators... 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); }
182 // If the user wants a 'default' case, they can choose to override this
183 // function. If this function is not overloaded in the users subclass, then
184 // this instruction just gets ignored.
186 // Note that you MUST override this function if your return type is not void.
188 void visitInstruction(Instruction &I) {} // Ignore unhandled instructions
193 } // End llvm namespace