src/llvm/include/llvm/IR/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_IR_USER_H
  20 #define LLVM_IR_USER_H
  21
  22 #include "llvm/ADT/iterator.h"
  23 #include "llvm/ADT/iterator_range.h"
  24 #include "llvm/IR/Value.h"
  25 #include "llvm/Support/ErrorHandling.h"
  26
  27 namespace llvm {
  28
  29 /// \brief Compile-time customization of User operands.
  30 ///
  31 /// Customizes operand-related allocators and accessors.
  32 template <class>
  33 struct OperandTraits;
  34
  35 class User : public Value {
  36   User(const User &) LLVM_DELETED_FUNCTION;
  37   void *operator new(size_t) LLVM_DELETED_FUNCTION;
  38   template <unsigned>
  39   friend struct HungoffOperandTraits;
  40   virtual void anchor();
  41 protected:
  42   /// \brief This is a pointer to the array of Uses for this User.
  43   ///
  44   /// For nodes of fixed arity (e.g. a binary operator) this array will live
  45   /// prefixed to some derived class instance.  For nodes of resizable variable
  46   /// arity (e.g. PHINodes, SwitchInst etc.), this memory will be dynamically
  47   /// allocated and should be destroyed by the classes' virtual dtor.
  48   Use *OperandList;
  49
  50   void *operator new(size_t s, unsigned Us);
  51   User(Type *ty, unsigned vty, Use *OpList, unsigned NumOps)
  52       : Value(ty, vty), OperandList(OpList) {
  53     NumOperands = NumOps;
  54   }
  55   Use *allocHungoffUses(unsigned) const;
  56   void dropHungoffUses() {
  57     Use::zap(OperandList, OperandList + NumOperands, true);
  58     OperandList = nullptr;
  59     // Reset NumOperands so User::operator delete() does the right thing.
  60     NumOperands = 0;
  61   }
  62 public:
  63   ~User() {
  64     Use::zap(OperandList, OperandList + NumOperands);
  65   }
  66   /// \brief Free memory allocated for User and Use objects.
  67   void operator delete(void *Usr);
  68   /// \brief Placement delete - required by std, but never called.
  69   void operator delete(void*, unsigned) {
  70     llvm_unreachable("Constructor throws?");
  71   }
  72   /// \brief Placement delete - required by std, but never called.
  73   void operator delete(void*, unsigned, bool) {
  74     llvm_unreachable("Constructor throws?");
  75   }
  76 protected:
  77   template <int Idx, typename U> static Use &OpFrom(const U *that) {
  78     return Idx < 0
  79       ? OperandTraits<U>::op_end(const_cast<U*>(that))[Idx]
  80       : OperandTraits<U>::op_begin(const_cast<U*>(that))[Idx];
  81   }
  82   template <int Idx> Use &Op() {
  83     return OpFrom<Idx>(this);
  84   }
  85   template <int Idx> const Use &Op() const {
  86     return OpFrom<Idx>(this);
  87   }
  88 public:
  89   Value *getOperand(unsigned i) const {
  90     assert(i < NumOperands && "getOperand() out of range!");
  91     return OperandList[i];
  92   }
  93   void setOperand(unsigned i, Value *Val) {
  94     assert(i < NumOperands && "setOperand() out of range!");
  95     assert((!isa<Constant>((const Value*)this) ||
  96             isa<GlobalValue>((const Value*)this)) &&
  97            "Cannot mutate a constant with setOperand!");
  98     OperandList[i] = Val;
  99   }
 100   const Use &getOperandUse(unsigned i) const {
 101     assert(i < NumOperands && "getOperandUse() out of range!");
 102     return OperandList[i];
 103   }
 104   Use &getOperandUse(unsigned i) {
 105     assert(i < NumOperands && "getOperandUse() out of range!");
 106     return OperandList[i];
 107   }
 108
 109   unsigned getNumOperands() const { return NumOperands; }
 110
 111   // ---------------------------------------------------------------------------
 112   // Operand Iterator interface...
 113   //
 114   typedef Use*       op_iterator;
 115   typedef const Use* const_op_iterator;
 116   typedef iterator_range<op_iterator> op_range;
 117   typedef iterator_range<const_op_iterator> const_op_range;
 118
 119   inline op_iterator       op_begin()       { return OperandList; }
 120   inline const_op_iterator op_begin() const { return OperandList; }
 121   inline op_iterator       op_end()         { return OperandList+NumOperands; }
 122   inline const_op_iterator op_end()   const { return OperandList+NumOperands; }
 123   inline op_range operands() {
 124     return op_range(op_begin(), op_end());
 125   }
 126   inline const_op_range operands() const {
 127     return const_op_range(op_begin(), op_end());
 128   }
 129
 130   /// \brief Iterator for directly iterating over the operand Values.
 131   struct value_op_iterator
 132       : iterator_adaptor_base<value_op_iterator, op_iterator,
 133                               std::random_access_iterator_tag, Value *,
 134                               ptrdiff_t, Value *, Value *> {
 135     explicit value_op_iterator(Use *U = nullptr) : iterator_adaptor_base(U) {}
 136
 137     Value *operator*() const { return *I; }
 138     Value *operator->() const { return operator*(); }
 139   };
 140
 141   inline value_op_iterator value_op_begin() {
 142     return value_op_iterator(op_begin());
 143   }
 144   inline value_op_iterator value_op_end() {
 145     return value_op_iterator(op_end());
 146   }
 147   inline iterator_range<value_op_iterator> operand_values() {
 148     return iterator_range<value_op_iterator>(value_op_begin(), value_op_end());
 149   }
 150
 151   /// \brief Drop all references to operands.
 152   ///
 153   /// This function is in charge of "letting go" of all objects that this User
 154   /// refers to.  This allows one to 'delete' a whole class at a time, even
 155   /// though there may be circular references...  First all references are
 156   /// dropped, and all use counts go to zero.  Then everything is deleted for
 157   /// real.  Note that no operations are valid on an object that has "dropped
 158   /// all references", except operator delete.
 159   void dropAllReferences() {
 160     for (Use &U : operands())
 161       U.set(nullptr);
 162   }
 163
 164   /// \brief Replace uses of one Value with another.
 165   ///
 166   /// Replaces all references to the "From" definition with references to the
 167   /// "To" definition.
 168   void replaceUsesOfWith(Value *From, Value *To);
 169
 170   // Methods for support type inquiry through isa, cast, and dyn_cast:
 171   static inline bool classof(const Value *V) {
 172     return isa<Instruction>(V) || isa<Constant>(V);
 173   }
 174 };
 175
 176 template<> struct simplify_type<User::op_iterator> {
 177   typedef Value* SimpleType;
 178   static SimpleType getSimplifiedValue(User::op_iterator &Val) {
 179     return Val->get();
 180   }
 181 };
 182 template<> struct simplify_type<User::const_op_iterator> {
 183   typedef /*const*/ Value* SimpleType;
 184   static SimpleType getSimplifiedValue(User::const_op_iterator &Val) {
 185     return Val->get();
 186   }
 187 };
 188
 189 } // End llvm namespace
 190
 191 #endif