llvm-6502/include/llvm/Support/InstVisitor.h
Vladimir Prus ef27d899fd Improve InstVisitor docs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28586 91177308-0d34-0410-b5e6-96231b3b80d8
2006-05-31 15:30:18 +00:00

210 lines
8.8 KiB
C++

//===- llvm/Support/InstVisitor.h - Define instruction visitors -*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_INSTVISITOR_H
#define LLVM_SUPPORT_INSTVISITOR_H
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
namespace llvm {
// 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 static_cast<SubClass*>(this)-> \
visit##CLASS_TO_VISIT(static_cast<CLASS_TO_VISIT&>(I))
/// @brief Base class for instruction visitors
///
/// Instruction visitors are used when you want to perform different action for
/// different kinds of instruction without without having to use lots of casts
/// and a big switch statement (in your code that is).
///
/// To define your own visitor, inherit from this class, specifying your
/// new type for the 'SubClass' template parameter, and "override" visitXXX
/// functions in your class. I say "overriding" because this class is defined
/// in terms of statically resolved overloading, not virtual functions.
///
/// For 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;
///
/// The defined has 'visit' methods for Instruction, and also for BasicBlock,
/// Function, and Module, which recursively process all conained instructions.
///
/// Note that if you don't implement visitXXX for some instruction type,
/// the visitXXX method for instruction superclass will be invoked. So
/// if instructions are added in the future, they will be automatically
/// supported, if you handle on of their superclasses.
///
/// The optional second template argument specifies the type that instruction
/// visitation functions should return. If you specify this, you *MUST* provide
/// an implementation of visitInstruction though!.
///
/// Note that this class 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.
template<typename SubClass, typename RetTy=void>
class InstVisitor {
//===--------------------------------------------------------------------===//
// Interface code - This is the public interface of the InstVisitor that you
// use to visit instructions...
//
public:
// Generic visit method - Allow visitation to all instructions in a range
template<class Iterator>
void visit(Iterator Start, Iterator End) {
while (Start != End)
static_cast<SubClass*>(this)->visit(*Start++);
}
// Define visitors for functions and basic blocks...
//
void visit(Module &M) {
static_cast<SubClass*>(this)->visitModule(M);
visit(M.begin(), M.end());
}
void visit(Function &F) {
static_cast<SubClass*>(this)->visitFunction(F);
visit(F.begin(), F.end());
}
void visit(BasicBlock &BB) {
static_cast<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 \
static_cast<SubClass*>(this)-> \
visit##OPCODE(static_cast<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); }
#include "llvm/Instruction.def"
// 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 visitUnwindInst(UnwindInst &I) { DELEGATE(TerminatorInst);}
RetTy visitUnreachableInst(UnreachableInst &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 visitSelectInst(SelectInst &I) { DELEGATE(Instruction); }
RetTy visitCallInst(CallInst &I) { DELEGATE(Instruction); }
RetTy visitShiftInst(ShiftInst &I) { DELEGATE(Instruction); }
RetTy visitVAArgInst(VAArgInst &I) { DELEGATE(Instruction); }
RetTy visitExtractElementInst(ExtractElementInst &I) { DELEGATE(Instruction); }
RetTy visitInsertElementInst(InsertElementInst &I) { DELEGATE(Instruction); }
RetTy visitShuffleVectorInst(ShuffleVectorInst &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
} // End llvm namespace
#endif