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...
80 // Generic visit method - Allow visitation to all instructions in a range
81 template<class Iterator>
82 void visit(Iterator Start, Iterator End) {
84 ((SubClass*)this)->visit(*Start++);
87 // Define visitors for functions and basic blocks...
89 void visit(Module &M) {
90 ((SubClass*)this)->visitModule(M);
91 visit(M.begin(), M.end());
93 void visit(Function &F) {
94 ((SubClass*)this)->visitFunction(F);
95 visit(F.begin(), F.end());
97 void visit(BasicBlock &BB) {
98 ((SubClass*)this)->visitBasicBlock(BB);
99 visit(BB.begin(), BB.end());
102 // Forwarding functions so that the user can visit with pointers AND refs.
103 void visit(Module *M) { visit(*M); }
104 void visit(Function *F) { visit(*F); }
105 void visit(BasicBlock *BB) { visit(*BB); }
106 RetTy visit(Instruction *I) { return visit(*I); }
108 // visit - Finally, code to visit an instruction...
110 RetTy visit(Instruction &I) {
111 switch (I.getOpcode()) {
112 default: assert(0 && "Unknown instruction type encountered!");
114 // Build the switch statement using the Instruction.def file...
115 #define HANDLE_INST(NUM, OPCODE, CLASS) \
116 case Instruction::OPCODE:return ((SubClass*)this)->visit##OPCODE((CLASS&)I);
117 #include "llvm/Instruction.def"
121 //===--------------------------------------------------------------------===//
122 // Visitation functions... these functions provide default fallbacks in case
123 // the user does not specify what to do for a particular instruction type.
124 // The default behavior is to generalize the instruction type to its subtype
125 // and try visiting the subtype. All of this should be inlined perfectly,
126 // because there are no virtual functions to get in the way.
129 // When visiting a module, function or basic block directly, these methods get
130 // called to indicate when transitioning into a new unit.
132 void visitModule (Module &M) {}
133 void visitFunction (Function &F) {}
134 void visitBasicBlock(BasicBlock &BB) {}
137 // Define instruction specific visitor functions that can be overridden to
138 // handle SPECIFIC instructions. These functions automatically define
139 // visitMul to proxy to visitBinaryOperator for instance in case the user does
140 // not need this generality.
142 // The one problem case we have to handle here though is that the PHINode
143 // class and opcode name are the exact same. Because of this, we cannot
144 // define visitPHINode (the inst version) to forward to visitPHINode (the
145 // generic version) without multiply defined symbols and recursion. To handle
146 // this, we do not autoexpand "Other" instructions, we do it manually.
148 #define HANDLE_INST(NUM, OPCODE, CLASS) \
149 RetTy visit##OPCODE(CLASS &I) { DELEGATE(CLASS); }
150 #include "llvm/Instruction.def"
152 // Specific Instruction type classes... note that all of the casts are
153 // necessary because we use the instruction classes as opaque types...
155 RetTy visitReturnInst(ReturnInst &I) { DELEGATE(TerminatorInst);}
156 RetTy visitBranchInst(BranchInst &I) { DELEGATE(TerminatorInst);}
157 RetTy visitSwitchInst(SwitchInst &I) { DELEGATE(TerminatorInst);}
158 RetTy visitInvokeInst(InvokeInst &I) { DELEGATE(TerminatorInst);}
159 RetTy visitUnwindInst(UnwindInst &I) { DELEGATE(TerminatorInst);}
160 RetTy visitUnreachableInst(UnreachableInst &I) { DELEGATE(TerminatorInst);}
161 RetTy visitSetCondInst(SetCondInst &I) { DELEGATE(BinaryOperator);}
162 RetTy visitMallocInst(MallocInst &I) { DELEGATE(AllocationInst);}
163 RetTy visitAllocaInst(AllocaInst &I) { DELEGATE(AllocationInst);}
164 RetTy visitFreeInst(FreeInst &I) { DELEGATE(Instruction); }
165 RetTy visitLoadInst(LoadInst &I) { DELEGATE(Instruction); }
166 RetTy visitStoreInst(StoreInst &I) { DELEGATE(Instruction); }
167 RetTy visitGetElementPtrInst(GetElementPtrInst &I){ DELEGATE(Instruction); }
168 RetTy visitPHINode(PHINode &I) { DELEGATE(Instruction); }
169 RetTy visitCastInst(CastInst &I) { DELEGATE(Instruction); }
170 RetTy visitSelectInst(SelectInst &I) { DELEGATE(Instruction); }
171 RetTy visitCallInst(CallInst &I) { DELEGATE(Instruction); }
172 RetTy visitShiftInst(ShiftInst &I) { DELEGATE(Instruction); }
173 RetTy visitVANextInst(VANextInst &I) { DELEGATE(Instruction); }
174 RetTy visitVAArgInst(VAArgInst &I) { DELEGATE(Instruction); }
176 // Next level propagators... if the user does not overload a specific
177 // instruction type, they can overload one of these to get the whole class
178 // of instructions...
180 RetTy visitTerminatorInst(TerminatorInst &I) { DELEGATE(Instruction); }
181 RetTy visitBinaryOperator(BinaryOperator &I) { DELEGATE(Instruction); }
182 RetTy visitAllocationInst(AllocationInst &I) { DELEGATE(Instruction); }
184 // If the user wants a 'default' case, they can choose to override this
185 // function. If this function is not overloaded in the users subclass, then
186 // this instruction just gets ignored.
188 // Note that you MUST override this function if your return type is not void.
190 void visitInstruction(Instruction &I) {} // Ignore unhandled instructions
195 } // End llvm namespace