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//===-- llvm/User.h - User class definition ---------------------*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This class defines the interface that one who 'use's a Value must implement.
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// Each instance of the Value class keeps track of what User's have handles
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// * Instructions are the largest class of User's.
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// * Constants may be users of other constants (think arrays and stuff)
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//===----------------------------------------------------------------------===//
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#include "llvm/Value.h"
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/// OperandTraits - Compile-time customization of
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/// operand-related allocators and accessors
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/// for use of the User class
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/// OperandTraits<User> - specialization to User
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struct OperandTraits<User> {
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static inline Use *op_begin(User*);
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static inline Use *op_end(User*);
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static inline unsigned operands(const User*);
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class User : public Value {
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User(const User &); // Do not implement
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void *operator new(size_t); // Do not implement
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friend struct HungoffOperandTraits;
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/// OperandList - This is a pointer to the array of Uses for this User.
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/// For nodes of fixed arity (e.g. a binary operator) this array will live
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/// prefixed to some derived class instance. For nodes of resizable variable
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/// arity (e.g. PHINodes, SwitchInst etc.), this memory will be dynamically
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/// allocated and should be destroyed by the classes' virtual dtor.
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/// NumOperands - The number of values used by this User.
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void *operator new(size_t s, unsigned Us);
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void *operator new(size_t s, unsigned Us, bool Prefix);
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User(const Type *ty, unsigned vty, Use *OpList, unsigned NumOps)
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: Value(ty, vty), OperandList(OpList), NumOperands(NumOps) {}
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Use *allocHungoffUses(unsigned) const;
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void dropHungoffUses(Use *U) {
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if (OperandList == U) {
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Use::zap(U, U->getImpliedUser(), true);
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if ((intptr_t(OperandList) & 1) == 0)
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Use::zap(OperandList, OperandList + NumOperands);
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/// operator delete - free memory allocated for User and Use objects
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void operator delete(void *Usr);
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/// placement delete - required by std, but never called.
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void operator delete(void*, unsigned) {
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assert(0 && "Constructor throws?");
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/// placement delete - required by std, but never called.
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void operator delete(void*, unsigned, bool) {
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assert(0 && "Constructor throws?");
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template <int Idx, typename U> static Use &OpFrom(const U *that) {
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? OperandTraits<U>::op_end(const_cast<U*>(that))[Idx]
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: OperandTraits<U>::op_begin(const_cast<U*>(that))[Idx];
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template <int Idx> Use &Op() {
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return OpFrom<Idx>(this);
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template <int Idx> const Use &Op() const {
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return OpFrom<Idx>(this);
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Value *getOperand(unsigned i) const {
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assert(i < NumOperands && "getOperand() out of range!");
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return OperandList[i];
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void setOperand(unsigned i, Value *Val) {
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assert(i < NumOperands && "setOperand() out of range!");
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assert((!isa<Constant>((const Value*)this) ||
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isa<GlobalValue>((const Value*)this)) &&
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"Cannot mutate a constant with setOperand!");
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OperandList[i] = Val;
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const Use &getOperandUse(unsigned i) const {
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assert(i < NumOperands && "getOperand() out of range!");
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return OperandList[i];
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Use &getOperandUse(unsigned i) {
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assert(i < NumOperands && "getOperand() out of range!");
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return OperandList[i];
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unsigned getNumOperands() const { return NumOperands; }
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// ---------------------------------------------------------------------------
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// Operand Iterator interface...
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typedef Use* op_iterator;
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typedef const Use* const_op_iterator;
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inline op_iterator op_begin() { return OperandList; }
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inline const_op_iterator op_begin() const { return OperandList; }
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inline op_iterator op_end() { return OperandList+NumOperands; }
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inline const_op_iterator op_end() const { return OperandList+NumOperands; }
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// dropAllReferences() - This function is in charge of "letting go" of all
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// objects that this User refers to. This allows one to
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// 'delete' a whole class at a time, even though there may be circular
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// references... First all references are dropped, and all use counts go to
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// zero. Then everything is deleted for real. Note that no operations are
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// valid on an object that has "dropped all references", except operator
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void dropAllReferences() {
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for (op_iterator i = op_begin(), e = op_end(); i != e; ++i)
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/// replaceUsesOfWith - Replaces all references to the "From" definition with
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/// references to the "To" definition.
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void replaceUsesOfWith(Value *From, Value *To);
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// Methods for support type inquiry through isa, cast, and dyn_cast:
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static inline bool classof(const User *) { return true; }
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static inline bool classof(const Value *V) {
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return isa<Instruction>(V) || isa<Constant>(V);
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inline Use *OperandTraits<User>::op_begin(User *U) {
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return U->op_begin();
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inline Use *OperandTraits<User>::op_end(User *U) {
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inline unsigned OperandTraits<User>::operands(const User *U) {
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return U->getNumOperands();
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template<> struct simplify_type<User::op_iterator> {
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typedef Value* SimpleType;
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static SimpleType getSimplifiedValue(const User::op_iterator &Val) {
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return static_cast<SimpleType>(Val->get());
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template<> struct simplify_type<const User::op_iterator>
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: public simplify_type<User::op_iterator> {};
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template<> struct simplify_type<User::const_op_iterator> {
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typedef Value* SimpleType;
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static SimpleType getSimplifiedValue(const User::const_op_iterator &Val) {
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return static_cast<SimpleType>(Val->get());
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template<> struct simplify_type<const User::const_op_iterator>
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: public simplify_type<User::const_op_iterator> {};
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// value_use_iterator::getOperandNo - Requires the definition of the User class.
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template<typename UserTy>
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unsigned value_use_iterator<UserTy>::getOperandNo() const {
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return U - U->getUser()->op_begin();
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} // End llvm namespace