lib/VMCore/User.cpp

   1 //===-- User.cpp - Implement the User class -------------------------------===//
   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 #include "llvm/Constant.h"
  11 #include "llvm/GlobalValue.h"
  12 #include "llvm/User.h"
  13
  14 namespace llvm {
  15
  16 //===----------------------------------------------------------------------===//
  17 //                                 User Class
  18 //===----------------------------------------------------------------------===//
  19
  20 // replaceUsesOfWith - Replaces all references to the "From" definition with
  21 // references to the "To" definition.
  22 //
  23 void User::replaceUsesOfWith(Value *From, Value *To) {
  24   if (From == To) return;   // Duh what?
  25
  26   assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&
  27          "Cannot call User::replaceUsesOfWith on a constant!");
  28
  29   for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
  30     if (getOperand(i) == From) {  // Is This operand is pointing to oldval?
  31       // The side effects of this setOperand call include linking to
  32       // "To", adding "this" to the uses list of To, and
  33       // most importantly, removing "this" from the use list of "From".
  34       setOperand(i, To); // Fix it now...
  35     }
  36 }
  37
  38 //===----------------------------------------------------------------------===//
  39 //                         User allocHungoffUses Implementation
  40 //===----------------------------------------------------------------------===//
  41
  42 Use *User::allocHungoffUses(unsigned N) const {
  43   Use *Begin = static_cast<Use*>(::operator new(sizeof(Use) * N
  44                                                 + sizeof(AugmentedUse)
  45                                                 - sizeof(Use)));
  46   Use *End = Begin + N;
  47   PointerIntPair<User*, 1, unsigned>&
  48     ref(static_cast<AugmentedUse&>(End[-1]).ref);
  49   ref.setPointer(const_cast<User*>(this));
  50   ref.setInt(1);
  51   return Use::initTags(Begin, End);
  52 }
  53
  54 //===----------------------------------------------------------------------===//
  55 //                         User operator new Implementations
  56 //===----------------------------------------------------------------------===//
  57
  58 void *User::operator new(size_t s, unsigned Us) {
  59   void *Storage = ::operator new(s + sizeof(Use) * Us);
  60   Use *Start = static_cast<Use*>(Storage);
  61   Use *End = Start + Us;
  62   User *Obj = reinterpret_cast<User*>(End);
  63   Obj->OperandList = Start;
  64   Obj->NumOperands = Us;
  65   Use::initTags(Start, End);
  66   return Obj;
  67 }
  68
  69 //===----------------------------------------------------------------------===//
  70 //                         User operator delete Implementation
  71 //===----------------------------------------------------------------------===//
  72
  73 void User::operator delete(void *Usr) {
  74   User *Start = static_cast<User*>(Usr);
  75   Use *Storage = static_cast<Use*>(Usr) - Start->NumOperands;
  76   // If there were hung-off uses, they will have been freed already and
  77   // NumOperands reset to 0, so here we just free the User itself.
  78   ::operator delete(Storage);
  79 }
  80
  81 } // End llvm namespace