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//===- llvm/Support/InstVisitor.h - Define instruction visitors --*- C++ -*--=//
//
// This template class is used to define instruction visitors in a typesafe
// manner without having to use lots of casts and a big switch statement (in
// your code that is). The win here is that if instructions are added in the
// future, they will be added to the InstVisitor<T> class, allowing you to
// automatically support them (if you handle on of their superclasses).
//
// Note that this library is specifically designed as a template to avoid
// virtual function call overhead. Defining and using an InstVisitor is just as
// efficient as having your own switch statement over the instruction opcode.
//
// InstVisitor Usage:
// You define InstVisitors from inheriting from the InstVisitor base class
// and "overriding" functions in your class. I say "overriding" because this
// class is defined in terms of statically resolved overloading, not virtual
// functions. As an example, here is a visitor that counts the number of malloc
// instructions processed:
//
// // Declare the class. Note that we derive from InstVisitor instantiated
// // with _our new subclasses_ type.
// //
// struct CountMallocVisitor : public InstVisitor<CountMallocVisitor> {
// unsigned Count;
// CountMallocVisitor() : Count(0) {}
//
// void visitMallocInst(MallocInst *MI) { ++Count; }
// };
//
// And this class would be used like this:
// CountMallocVistor CMV;
// CMV.visit(function);
// NumMallocs = CMV.Count;
//
// Returning a value from the visitation function:
// The InstVisitor class takes an optional second template argument that
// specifies what type the instruction visitation functions should return. If
// you specify this, you *MUST* provide an implementation of visitInstruction
// though!.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_INSTVISITOR_H
#define LLVM_SUPPORT_INSTVISITOR_H
#include "llvm/Instruction.h"
class Module;
// We operate on opaque instruction classes, so forward declare all instruction
// types now...
//
#define HANDLE_INST(NUM, OPCODE, CLASS) class CLASS;
#include "llvm/Instruction.def"
// Forward declare the intermediate types...
class TerminatorInst; class BinaryOperator;
class AllocationInst;
#define DELEGATE(CLASS_TO_VISIT) \
return ((SubClass*)this)->visit##CLASS_TO_VISIT((CLASS_TO_VISIT&)I)
template<typename SubClass, typename RetTy=void>
struct InstVisitor {
virtual ~InstVisitor() {} // We are meant to be derived from
//===--------------------------------------------------------------------===//
// Interface code - This is the public interface of the InstVisitor that you
// use to visit instructions...
//
// Generic visit method - Allow visitation to all instructions in a range
template<class Iterator>
void visit(Iterator Start, Iterator End) {
while (Start != End)
((SubClass*)this)->visit(*Start++);
}
// Define visitors for modules, functions and basic blocks...
//
void visit(Module &M) {
((SubClass*)this)->visitModule(M);
visit(M.begin(), M.end());
}
void visit(Function &F) {
((SubClass*)this)->visitFunction(F);
visit(F.begin(), F.end());
}
void visit(BasicBlock &BB) {
((SubClass*)this)->visitBasicBlock(BB);
visit(BB.begin(), BB.end());
}
// Forwarding functions so that the user can visit with pointers AND refs.
void visit(Module *M) { visit(*M); }
void visit(Function *F) { visit(*F); }
void visit(BasicBlock *BB) { visit(*BB); }
RetTy visit(Instruction *I) { return visit(*I); }
// visit - Finally, code to visit an instruction...
//
RetTy visit(Instruction &I) {
switch (I.getOpcode()) {
default: assert(0 && "Unknown instruction type encountered!");
abort();
// Build the switch statement using the Instruction.def file...
#define HANDLE_INST(NUM, OPCODE, CLASS) \
case Instruction::OPCODE:return ((SubClass*)this)->visit##OPCODE((CLASS&)I);
#include "llvm/Instruction.def"
}
}
//===--------------------------------------------------------------------===//
// Visitation functions... these functions provide default fallbacks in case
// the user does not specify what to do for a particular instruction type.
// The default behavior is to generalize the instruction type to its subtype
// and try visiting the subtype. All of this should be inlined perfectly,
// because there are no virtual functions to get in the way.
//
// When visiting a module, function or basic block directly, these methods get
// called to indicate when transitioning into a new unit.
//
void visitModule (Module &M) {}
void visitFunction (Function &F) {}
void visitBasicBlock(BasicBlock &BB) {}
// Define instruction specific visitor functions that can be overridden to
// handle SPECIFIC instructions. These functions automatically define
// visitMul to proxy to visitBinaryOperator for instance in case the user does
// not need this generality.
//
// The one problem case we have to handle here though is that the PHINode
// class and opcode name are the exact same. Because of this, we cannot
// define visitPHINode (the inst version) to forward to visitPHINode (the
// generic version) without multiply defined symbols and recursion. To handle
// this, we do not autoexpand "Other" instructions, we do it manually.
//
#define HANDLE_INST(NUM, OPCODE, CLASS) \
RetTy visit##OPCODE(CLASS &I) { DELEGATE(CLASS); }
#define HANDLE_OTHER_INST(NUM, OPCODE, CLASS) // Ignore "other" instructions
#include "llvm/Instruction.def"
// Implement all "other" instructions, except for PHINode
RetTy visitCast(CastInst &I) { DELEGATE(CastInst); }
RetTy visitCall(CallInst &I) { DELEGATE(CallInst); }
RetTy visitShr(ShiftInst &I) { DELEGATE(ShiftInst); }
RetTy visitShl(ShiftInst &I) { DELEGATE(ShiftInst); }
RetTy visitVarArg(VarArgInst &I) { DELEGATE(VarArgInst); }
RetTy visitUserOp1(Instruction &I) { DELEGATE(Instruction); }
RetTy visitUserOp2(Instruction &I) { DELEGATE(Instruction); }
// Specific Instruction type classes... note that all of the casts are
// necessary because we use the instruction classes as opaque types...
//
RetTy visitReturnInst(ReturnInst &I) { DELEGATE(TerminatorInst);}
RetTy visitBranchInst(BranchInst &I) { DELEGATE(TerminatorInst);}
RetTy visitSwitchInst(SwitchInst &I) { DELEGATE(TerminatorInst);}
RetTy visitInvokeInst(InvokeInst &I) { DELEGATE(TerminatorInst);}
RetTy visitSetCondInst(SetCondInst &I) { DELEGATE(BinaryOperator);}
RetTy visitMallocInst(MallocInst &I) { DELEGATE(AllocationInst);}
RetTy visitAllocaInst(AllocaInst &I) { DELEGATE(AllocationInst);}
RetTy visitFreeInst(FreeInst &I) { DELEGATE(Instruction); }
RetTy visitLoadInst(LoadInst &I) { DELEGATE(Instruction); }
RetTy visitStoreInst(StoreInst &I) { DELEGATE(Instruction); }
RetTy visitGetElementPtrInst(GetElementPtrInst &I){ DELEGATE(Instruction); }
RetTy visitPHINode(PHINode &I) { DELEGATE(Instruction); }
RetTy visitCastInst(CastInst &I) { DELEGATE(Instruction); }
RetTy visitCallInst(CallInst &I) { DELEGATE(Instruction); }
RetTy visitShiftInst(ShiftInst &I) { DELEGATE(Instruction); }
RetTy visitVarArgInst(VarArgInst &I) { DELEGATE(Instruction); }
// Next level propagators... if the user does not overload a specific
// instruction type, they can overload one of these to get the whole class
// of instructions...
//
RetTy visitTerminatorInst(TerminatorInst &I) { DELEGATE(Instruction); }
RetTy visitBinaryOperator(BinaryOperator &I) { DELEGATE(Instruction); }
RetTy visitAllocationInst(AllocationInst &I) { DELEGATE(Instruction); }
// If the user wants a 'default' case, they can choose to override this
// function. If this function is not overloaded in the users subclass, then
// this instruction just gets ignored.
//
// Note that you MUST override this function if your return type is not void.
//
void visitInstruction(Instruction &I) {} // Ignore unhandled instructions
};
#undef DELEGATE
#endif
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