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   // Allocate the array of Uses, followed by a pointer (with bottom bit set) to
  44   // the User.
  45   size_t size = N * sizeof(Use) + sizeof(Use::UserRef);
  46   Use *Begin = static_cast<Use*>(::operator new(size));
  47   Use *End = Begin + N;
  48   (void) new(End) Use::UserRef(const_cast<User*>(this), 1);
  49   return Use::initTags(Begin, End);
  50 }
  51
  52 //===----------------------------------------------------------------------===//
  53 //                         User operator new Implementations
  54 //===----------------------------------------------------------------------===//
  55
  56 void *User::operator new(size_t s, unsigned Us) {
  57   void *Storage = ::operator new(s + sizeof(Use) * Us);
  58   Use *Start = static_cast<Use*>(Storage);
  59   Use *End = Start + Us;
  60   User *Obj = reinterpret_cast<User*>(End);
  61   Obj->OperandList = Start;
  62   Obj->NumOperands = Us;
  63   Use::initTags(Start, End);
  64   return Obj;
  65 }
  66
  67 //===----------------------------------------------------------------------===//
  68 //                         User operator delete Implementation
  69 //===----------------------------------------------------------------------===//
  70
  71 void User::operator delete(void *Usr) {
  72   User *Start = static_cast<User*>(Usr);
  73   Use *Storage = static_cast<Use*>(Usr) - Start->NumOperands;
  74   // If there were hung-off uses, they will have been freed already and
  75   // NumOperands reset to 0, so here we just free the User itself.
  76   ::operator delete(Storage);
  77 }
  78
  79 } // End llvm namespace