src/llvm/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 uses 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 Users.
  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/Support/ErrorHandling.h"
  23 #include "llvm/Value.h"
  24
  25 namespace llvm {
  26
  27 /// OperandTraits - Compile-time customization of
  28 /// operand-related allocators and accessors
  29 /// for use of the User class
  30 template <class>
  31 struct OperandTraits;
  32
  33 class User : public Value {
  34   User(const User &) LLVM_DELETED_FUNCTION;
  35   void *operator new(size_t) LLVM_DELETED_FUNCTION;
  36   template <unsigned>
  37   friend struct HungoffOperandTraits;
  38   virtual void anchor();
  39 protected:
  40   /// OperandList - This is a pointer to the array of Uses for this User.
  41   /// For nodes of fixed arity (e.g. a binary operator) this array will live
  42   /// prefixed to some derived class instance.  For nodes of resizable variable
  43   /// arity (e.g. PHINodes, SwitchInst etc.), this memory will be dynamically
  44   /// allocated and should be destroyed by the classes' virtual dtor.
  45   Use *OperandList;
  46
  47   /// NumOperands - The number of values used by this User.
  48   ///
  49   unsigned NumOperands;
  50
  51   void *operator new(size_t s, unsigned Us);
  52   User(Type *ty, unsigned vty, Use *OpList, unsigned NumOps)
  53     : Value(ty, vty), OperandList(OpList), NumOperands(NumOps) {}
  54   Use *allocHungoffUses(unsigned) const;
  55   void dropHungoffUses() {
  56     Use::zap(OperandList, OperandList + NumOperands, true);
  57     OperandList = 0;
  58     // Reset NumOperands so User::operator delete() does the right thing.
  59     NumOperands = 0;
  60   }
  61 public:
  62   ~User() {
  63     Use::zap(OperandList, OperandList + NumOperands);
  64   }
  65   /// operator delete - free memory allocated for User and Use objects
  66   void operator delete(void *Usr);
  67   /// placement delete - required by std, but never called.
  68   void operator delete(void*, unsigned) {
  69     llvm_unreachable("Constructor throws?");
  70   }
  71   /// placement delete - required by std, but never called.
  72   void operator delete(void*, unsigned, bool) {
  73     llvm_unreachable("Constructor throws?");
  74   }
  75 protected:
  76   template <int Idx, typename U> static Use &OpFrom(const U *that) {
  77     return Idx < 0
  78       ? OperandTraits<U>::op_end(const_cast<U*>(that))[Idx]
  79       : OperandTraits<U>::op_begin(const_cast<U*>(that))[Idx];
  80   }
  81   template <int Idx> Use &Op() {
  82     return OpFrom<Idx>(this);
  83   }
  84   template <int Idx> const Use &Op() const {
  85     return OpFrom<Idx>(this);
  86   }
  87 public:
  88   Value *getOperand(unsigned i) const {
  89     assert(i < NumOperands && "getOperand() out of range!");
  90     return OperandList[i];
  91   }
  92   void setOperand(unsigned i, Value *Val) {
  93     assert(i < NumOperands && "setOperand() out of range!");
  94     assert((!isa<Constant>((const Value*)this) ||
  95             isa<GlobalValue>((const Value*)this)) &&
  96            "Cannot mutate a constant with setOperand!");
  97     OperandList[i] = Val;
  98   }
  99   const Use &getOperandUse(unsigned i) const {
 100     assert(i < NumOperands && "getOperandUse() out of range!");
 101     return OperandList[i];
 102   }
 103   Use &getOperandUse(unsigned i) {
 104     assert(i < NumOperands && "getOperandUse() out of range!");
 105     return OperandList[i];
 106   }
 107
 108   unsigned getNumOperands() const { return NumOperands; }
 109
 110   // ---------------------------------------------------------------------------
 111   // Operand Iterator interface...
 112   //
 113   typedef Use*       op_iterator;
 114   typedef const Use* const_op_iterator;
 115
 116   inline op_iterator       op_begin()       { return OperandList; }
 117   inline const_op_iterator op_begin() const { return OperandList; }
 118   inline op_iterator       op_end()         { return OperandList+NumOperands; }
 119   inline const_op_iterator op_end()   const { return OperandList+NumOperands; }
 120
 121   // dropAllReferences() - This function is in charge of "letting go" of all
 122   // objects that this User refers to.  This allows one to
 123   // 'delete' a whole class at a time, even though there may be circular
 124   // references...  First all references are dropped, and all use counts go to
 125   // zero.  Then everything is deleted for real.  Note that no operations are
 126   // valid on an object that has "dropped all references", except operator
 127   // delete.
 128   //
 129   void dropAllReferences() {
 130     for (op_iterator i = op_begin(), e = op_end(); i != e; ++i)
 131       i->set(0);
 132   }
 133
 134   /// replaceUsesOfWith - Replaces all references to the "From" definition with
 135   /// references to the "To" definition.
 136   ///
 137   void replaceUsesOfWith(Value *From, Value *To);
 138
 139   // Methods for support type inquiry through isa, cast, and dyn_cast:
 140   static inline bool classof(const User *) { return true; }
 141   static inline bool classof(const Value *V) {
 142     return isa<Instruction>(V) || isa<Constant>(V);
 143   }
 144 };
 145
 146 template<> struct simplify_type<User::op_iterator> {
 147   typedef Value* SimpleType;
 148
 149   static SimpleType getSimplifiedValue(const User::op_iterator &Val) {
 150     return static_cast<SimpleType>(Val->get());
 151   }
 152 };
 153
 154 template<> struct simplify_type<const User::op_iterator>
 155   : public simplify_type<User::op_iterator> {};
 156
 157 template<> struct simplify_type<User::const_op_iterator> {
 158   typedef Value* SimpleType;
 159
 160   static SimpleType getSimplifiedValue(const User::const_op_iterator &Val) {
 161     return static_cast<SimpleType>(Val->get());
 162   }
 163 };
 164
 165 template<> struct simplify_type<const User::const_op_iterator>
 166   : public simplify_type<User::const_op_iterator> {};
 167
 168
 169 // value_use_iterator::getOperandNo - Requires the definition of the User class.
 170 template<typename UserTy>
 171 unsigned value_use_iterator<UserTy>::getOperandNo() const {
 172   return U - U->getUser()->op_begin();
 173 }
 174
 175 } // End llvm namespace
 176
 177 #endif