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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/IR/User.h"
11 #include "llvm/IR/Constant.h"
12 #include "llvm/IR/GlobalValue.h"
13 #include "llvm/IR/Operator.h"
14 
15 namespace llvm {
16 
17 //===----------------------------------------------------------------------===//
18 //                                 User Class
19 //===----------------------------------------------------------------------===//
20 
anchor()21 void User::anchor() {}
22 
23 // replaceUsesOfWith - Replaces all references to the "From" definition with
24 // references to the "To" definition.
25 //
replaceUsesOfWith(Value * From,Value * To)26 void User::replaceUsesOfWith(Value *From, Value *To) {
27   if (From == To) return;   // Duh what?
28 
29   assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&
30          "Cannot call User::replaceUsesOfWith on a constant!");
31 
32   for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
33     if (getOperand(i) == From) {  // Is This operand is pointing to oldval?
34       // The side effects of this setOperand call include linking to
35       // "To", adding "this" to the uses list of To, and
36       // most importantly, removing "this" from the use list of "From".
37       setOperand(i, To); // Fix it now...
38     }
39 }
40 
41 //===----------------------------------------------------------------------===//
42 //                         User allocHungoffUses Implementation
43 //===----------------------------------------------------------------------===//
44 
allocHungoffUses(unsigned N) const45 Use *User::allocHungoffUses(unsigned N) const {
46   // Allocate the array of Uses, followed by a pointer (with bottom bit set) to
47   // the User.
48   size_t size = N * sizeof(Use) + sizeof(Use::UserRef);
49   Use *Begin = static_cast<Use*>(::operator new(size));
50   Use *End = Begin + N;
51   (void) new(End) Use::UserRef(const_cast<User*>(this), 1);
52   return Use::initTags(Begin, End);
53 }
54 
55 //===----------------------------------------------------------------------===//
56 //                         User operator new Implementations
57 //===----------------------------------------------------------------------===//
58 
operator new(size_t s,unsigned Us)59 void *User::operator new(size_t s, unsigned Us) {
60   void *Storage = ::operator new(s + sizeof(Use) * Us);
61   Use *Start = static_cast<Use*>(Storage);
62   Use *End = Start + Us;
63   User *Obj = reinterpret_cast<User*>(End);
64   Obj->OperandList = Start;
65   Obj->NumOperands = Us;
66   Use::initTags(Start, End);
67   return Obj;
68 }
69 
70 //===----------------------------------------------------------------------===//
71 //                         User operator delete Implementation
72 //===----------------------------------------------------------------------===//
73 
operator delete(void * Usr)74 void User::operator delete(void *Usr) {
75   User *Start = static_cast<User*>(Usr);
76   Use *Storage = static_cast<Use*>(Usr) - Start->NumOperands;
77   // If there were hung-off uses, they will have been freed already and
78   // NumOperands reset to 0, so here we just free the User itself.
79   ::operator delete(Storage);
80 }
81 
82 //===----------------------------------------------------------------------===//
83 //                             Operator Class
84 //===----------------------------------------------------------------------===//
85 
~Operator()86 Operator::~Operator() {
87   llvm_unreachable("should never destroy an Operator");
88 }
89 
90 } // End llvm namespace
91