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"
59 // We operate on opaque instruction classes, so forward declare all instruction
62 #define HANDLE_INST(NUM, OPCODE, CLASS) class CLASS;
63 #include "llvm/Instruction.def"
65 // Forward declare the intermediate types...
66 class TerminatorInst; class BinaryOperator;
69 #define DELEGATE(CLASS_TO_VISIT) \
70 return ((SubClass*)this)->visit##CLASS_TO_VISIT((CLASS_TO_VISIT&)I)
73 template<typename SubClass, typename RetTy=void>
75 virtual ~InstVisitor() {} // We are meant to be derived from
77 //===--------------------------------------------------------------------===//
78 // Interface code - This is the public interface of the InstVisitor that you
79 // use to visit instructions...
82 // Generic visit method - Allow visitation to all instructions in a range
83 template<class Iterator>
84 void visit(Iterator Start, Iterator End) {
86 ((SubClass*)this)->visit(*Start++);
89 // Define visitors for functions and basic blocks...
91 void visit(Function &F) {
92 ((SubClass*)this)->visitFunction(F);
93 visit(F.begin(), F.end());
95 void visit(BasicBlock &BB) {
96 ((SubClass*)this)->visitBasicBlock(BB);
97 visit(BB.begin(), BB.end());
100 // Forwarding functions so that the user can visit with pointers AND refs.
101 void visit(Module *M) { visit(*M); }
102 void visit(Function *F) { visit(*F); }
103 void visit(BasicBlock *BB) { visit(*BB); }
104 RetTy visit(Instruction *I) { return visit(*I); }
106 // visit - Finally, code to visit an instruction...
108 RetTy visit(Instruction &I) {
109 switch (I.getOpcode()) {
110 default: assert(0 && "Unknown instruction type encountered!");
112 // Build the switch statement using the Instruction.def file...
113 #define HANDLE_INST(NUM, OPCODE, CLASS) \
114 case Instruction::OPCODE:return ((SubClass*)this)->visit##OPCODE((CLASS&)I);
115 #include "llvm/Instruction.def"
119 //===--------------------------------------------------------------------===//
120 // Visitation functions... these functions provide default fallbacks in case
121 // the user does not specify what to do for a particular instruction type.
122 // The default behavior is to generalize the instruction type to its subtype
123 // and try visiting the subtype. All of this should be inlined perfectly,
124 // because there are no virtual functions to get in the way.
127 // When visiting a module, function or basic block directly, these methods get
128 // called to indicate when transitioning into a new unit.
130 void visitFunction (Function &F) {}
131 void visitBasicBlock(BasicBlock &BB) {}
134 // Define instruction specific visitor functions that can be overridden to
135 // handle SPECIFIC instructions. These functions automatically define
136 // visitMul to proxy to visitBinaryOperator for instance in case the user does
137 // not need this generality.
139 // The one problem case we have to handle here though is that the PHINode
140 // class and opcode name are the exact same. Because of this, we cannot
141 // define visitPHINode (the inst version) to forward to visitPHINode (the
142 // generic version) without multiply defined symbols and recursion. To handle
143 // this, we do not autoexpand "Other" instructions, we do it manually.
145 #define HANDLE_INST(NUM, OPCODE, CLASS) \
146 RetTy visit##OPCODE(CLASS &I) { DELEGATE(CLASS); }
147 #include "llvm/Instruction.def"
149 // Specific Instruction type classes... note that all of the casts are
150 // necessary because we use the instruction classes as opaque types...
152 RetTy visitReturnInst(ReturnInst &I) { DELEGATE(TerminatorInst);}
153 RetTy visitBranchInst(BranchInst &I) { DELEGATE(TerminatorInst);}
154 RetTy visitSwitchInst(SwitchInst &I) { DELEGATE(TerminatorInst);}
155 RetTy visitInvokeInst(InvokeInst &I) { DELEGATE(TerminatorInst);}
156 RetTy visitUnwindInst(UnwindInst &I) { DELEGATE(TerminatorInst);}
157 RetTy visitSetCondInst(SetCondInst &I) { DELEGATE(BinaryOperator);}
158 RetTy visitMallocInst(MallocInst &I) { DELEGATE(AllocationInst);}
159 RetTy visitAllocaInst(AllocaInst &I) { DELEGATE(AllocationInst);}
160 RetTy visitFreeInst(FreeInst &I) { DELEGATE(Instruction); }
161 RetTy visitLoadInst(LoadInst &I) { DELEGATE(Instruction); }
162 RetTy visitStoreInst(StoreInst &I) { DELEGATE(Instruction); }
163 RetTy visitGetElementPtrInst(GetElementPtrInst &I){ DELEGATE(Instruction); }
164 RetTy visitPHINode(PHINode &I) { DELEGATE(Instruction); }
165 RetTy visitCastInst(CastInst &I) { DELEGATE(Instruction); }
166 RetTy visitSelectInst(SelectInst &I) { DELEGATE(Instruction); }
167 RetTy visitCallInst(CallInst &I) { DELEGATE(Instruction); }
168 RetTy visitShiftInst(ShiftInst &I) { DELEGATE(Instruction); }
169 RetTy visitVANextInst(VANextInst &I) { DELEGATE(Instruction); }
170 RetTy visitVAArgInst(VAArgInst &I) { DELEGATE(Instruction); }
172 // Next level propagators... if the user does not overload a specific
173 // instruction type, they can overload one of these to get the whole class
174 // of instructions...
176 RetTy visitTerminatorInst(TerminatorInst &I) { DELEGATE(Instruction); }
177 RetTy visitBinaryOperator(BinaryOperator &I) { DELEGATE(Instruction); }
178 RetTy visitAllocationInst(AllocationInst &I) { DELEGATE(Instruction); }
180 // If the user wants a 'default' case, they can choose to override this
181 // function. If this function is not overloaded in the users subclass, then
182 // this instruction just gets ignored.
184 // Note that you MUST override this function if your return type is not void.
186 void visitInstruction(Instruction &I) {} // Ignore unhandled instructions
191 } // End llvm namespace