include/llvm/User.h

   1 //===-- llvm/User.h - User class definition ---------------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This class defines the interface that one who 'use's a Value must implement.
  11 // Each instance of the Value class keeps track of what User's have handles
  12 // to it.
  13 //
  14 //  * Instructions are the largest class of User's.
  15 //  * Constants may be users of other constants (think arrays and stuff)
  16 //
  17 //===----------------------------------------------------------------------===//
  18
  19 #ifndef LLVM_USER_H
  20 #define LLVM_USER_H
  21
  22 #include "llvm/Value.h"
  23
  24 namespace llvm {
  25
  26 /// OperandTraits - Compile-time customization of
  27 /// operand-related allocators and accessors
  28 /// for use of the User class
  29 template <class>
  30 struct OperandTraits;
  31
  32 class User;
  33
  34 /// OperandTraits<User> - specialization to User
  35 template <>
  36 struct OperandTraits<User> {
  37   static inline Use *op_begin(User*);
  38   static inline Use *op_end(User*);
  39   static inline unsigned operands(const User*);
  40   template <class U>
  41   struct Layout {
  42     typedef U overlay;
  43   };
  44 };
  45
  46 class User : public Value {
  47   User(const User &);             // Do not implement
  48   void *operator new(size_t);     // Do not implement
  49   template <unsigned>
  50   friend struct HungoffOperandTraits;
  51 protected:
  52   /// OperandList - This is a pointer to the array of Uses for this User.
  53   /// For nodes of fixed arity (e.g. a binary operator) this array will live
  54   /// prefixed to some derived class instance.  For nodes of resizable variable
  55   /// arity (e.g. PHINodes, SwitchInst etc.), this memory will be dynamically
  56   /// allocated and should be destroyed by the classes' virtual dtor.
  57   Use *OperandList;
  58
  59   /// NumOperands - The number of values used by this User.
  60   ///
  61   unsigned NumOperands;
  62
  63   void *operator new(size_t s, unsigned Us);
  64   void *operator new(size_t s, unsigned Us, bool Prefix);
  65   User(const Type *ty, unsigned vty, Use *OpList, unsigned NumOps)
  66     : Value(ty, vty), OperandList(OpList), NumOperands(NumOps) {}
  67   Use *allocHungoffUses(unsigned) const;
  68   void dropHungoffUses(Use *U) {
  69     if (OperandList == U) {
  70       OperandList = 0;
  71       NumOperands = 0;
  72     }
  73     Use::zap(U, U->getImpliedUser(), true);
  74   }
  75 public:
  76   ~User() {
  77     if ((intptr_t(OperandList) & 1) == 0)
  78       Use::zap(OperandList, OperandList + NumOperands);
  79   }
  80   /// operator delete - free memory allocated for User and Use objects
  81   void operator delete(void *Usr);
  82   /// placement delete - required by std, but never called.
  83   void operator delete(void*, unsigned) {
  84     assert(0 && "Constructor throws?");
  85   }
  86   /// placement delete - required by std, but never called.
  87   void operator delete(void*, unsigned, bool) {
  88     assert(0 && "Constructor throws?");
  89   }
  90 protected:
  91   template <int Idx, typename U> static Use &OpFrom(const U *that) {
  92     return Idx < 0
  93       ? OperandTraits<U>::op_end(const_cast<U*>(that))[Idx]
  94       : OperandTraits<U>::op_begin(const_cast<U*>(that))[Idx];
  95   }
  96   template <int Idx> Use &Op() {
  97     return OpFrom<Idx>(this);
  98   }
  99   template <int Idx> const Use &Op() const {
 100     return OpFrom<Idx>(this);
 101   }
 102 public:
 103   Value *getOperand(unsigned i) const {
 104     assert(i < NumOperands && "getOperand() out of range!");
 105     return OperandList[i];
 106   }
 107   void setOperand(unsigned i, Value *Val) {
 108     assert(i < NumOperands && "setOperand() out of range!");
 109     assert((!isa<Constant>((const Value*)this) ||
 110             isa<GlobalValue>((const Value*)this)) &&
 111            "Cannot mutate a constant with setOperand!");
 112     OperandList[i] = Val;
 113   }
 114   const Use &getOperandUse(unsigned i) const {
 115     assert(i < NumOperands && "getOperand() out of range!");
 116     return OperandList[i];
 117   }
 118   Use &getOperandUse(unsigned i) {
 119     assert(i < NumOperands && "getOperand() out of range!");
 120     return OperandList[i];
 121   }
 122
 123   unsigned getNumOperands() const { return NumOperands; }
 124
 125   // ---------------------------------------------------------------------------
 126   // Operand Iterator interface...
 127   //
 128   typedef Use*       op_iterator;
 129   typedef const Use* const_op_iterator;
 130
 131   inline op_iterator       op_begin()       { return OperandList; }
 132   inline const_op_iterator op_begin() const { return OperandList; }
 133   inline op_iterator       op_end()         { return OperandList+NumOperands; }
 134   inline const_op_iterator op_end()   const { return OperandList+NumOperands; }
 135
 136   // dropAllReferences() - This function is in charge of "letting go" of all
 137   // objects that this User refers to.  This allows one to
 138   // 'delete' a whole class at a time, even though there may be circular
 139   // references...  First all references are dropped, and all use counts go to
 140   // zero.  Then everything is deleted for real.  Note that no operations are
 141   // valid on an object that has "dropped all references", except operator
 142   // delete.
 143   //
 144   void dropAllReferences() {
 145     for (op_iterator i = op_begin(), e = op_end(); i != e; ++i)
 146       i->set(0);
 147   }
 148
 149   /// replaceUsesOfWith - Replaces all references to the "From" definition with
 150   /// references to the "To" definition.
 151   ///
 152   void replaceUsesOfWith(Value *From, Value *To);
 153
 154   // Methods for support type inquiry through isa, cast, and dyn_cast:
 155   static inline bool classof(const User *) { return true; }
 156   static inline bool classof(const Value *V) {
 157     return isa<Instruction>(V) || isa<Constant>(V);
 158   }
 159 };
 160
 161 inline Use *OperandTraits<User>::op_begin(User *U) {
 162   return U->op_begin();
 163 }
 164
 165 inline Use *OperandTraits<User>::op_end(User *U) {
 166   return U->op_end();
 167 }
 168
 169 inline unsigned OperandTraits<User>::operands(const User *U) {
 170   return U->getNumOperands();
 171 }
 172
 173 template<> struct simplify_type<User::op_iterator> {
 174   typedef Value* SimpleType;
 175
 176   static SimpleType getSimplifiedValue(const User::op_iterator &Val) {
 177     return static_cast<SimpleType>(Val->get());
 178   }
 179 };
 180
 181 template<> struct simplify_type<const User::op_iterator>
 182   : public simplify_type<User::op_iterator> {};
 183
 184 template<> struct simplify_type<User::const_op_iterator> {
 185   typedef Value* SimpleType;
 186
 187   static SimpleType getSimplifiedValue(const User::const_op_iterator &Val) {
 188     return static_cast<SimpleType>(Val->get());
 189   }
 190 };
 191
 192 template<> struct simplify_type<const User::const_op_iterator>
 193   : public simplify_type<User::const_op_iterator> {};
 194
 195
 196 // value_use_iterator::getOperandNo - Requires the definition of the User class.
 197 template<typename UserTy>
 198 unsigned value_use_iterator<UserTy>::getOperandNo() const {
 199   return U - U->getUser()->op_begin();
 200 }
 201
 202 } // End llvm namespace
 203
 204 #endif