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
15namespace llvm {
16class BasicBlock;
17
18//===----------------------------------------------------------------------===//
19//                                 User Class
20//===----------------------------------------------------------------------===//
21
22void User::anchor() {}
23
24void User::replaceUsesOfWith(Value *From, Value *To) {
25  if (From == To) return;   // Duh what?
26
27  assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&
28         "Cannot call User::replaceUsesOfWith on a constant!");
29
30  for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
31    if (getOperand(i) == From) {  // Is This operand is pointing to oldval?
32      // The side effects of this setOperand call include linking to
33      // "To", adding "this" to the uses list of To, and
34      // most importantly, removing "this" from the use list of "From".
35      setOperand(i, To); // Fix it now...
36    }
37}
38
39//===----------------------------------------------------------------------===//
40//                         User allocHungoffUses Implementation
41//===----------------------------------------------------------------------===//
42
43void User::allocHungoffUses(unsigned N, bool IsPhi) {
44  assert(HasHungOffUses && "alloc must have hung off uses");
45
46  static_assert(AlignOf<Use>::Alignment >= AlignOf<Use::UserRef>::Alignment,
47                "Alignment is insufficient for 'hung-off-uses' pieces");
48  static_assert(AlignOf<Use::UserRef>::Alignment >=
49                    AlignOf<BasicBlock *>::Alignment,
50                "Alignment is insufficient for 'hung-off-uses' pieces");
51
52  // Allocate the array of Uses, followed by a pointer (with bottom bit set) to
53  // the User.
54  size_t size = N * sizeof(Use) + sizeof(Use::UserRef);
55  if (IsPhi)
56    size += N * sizeof(BasicBlock *);
57  Use *Begin = static_cast<Use*>(::operator new(size));
58  Use *End = Begin + N;
59  (void) new(End) Use::UserRef(const_cast<User*>(this), 1);
60  setOperandList(Use::initTags(Begin, End));
61}
62
63void User::growHungoffUses(unsigned NewNumUses, bool IsPhi) {
64  assert(HasHungOffUses && "realloc must have hung off uses");
65
66  unsigned OldNumUses = getNumOperands();
67
68  // We don't support shrinking the number of uses.  We wouldn't have enough
69  // space to copy the old uses in to the new space.
70  assert(NewNumUses > OldNumUses && "realloc must grow num uses");
71
72  Use *OldOps = getOperandList();
73  allocHungoffUses(NewNumUses, IsPhi);
74  Use *NewOps = getOperandList();
75
76  // Now copy from the old operands list to the new one.
77  std::copy(OldOps, OldOps + OldNumUses, NewOps);
78
79  // If this is a Phi, then we need to copy the BB pointers too.
80  if (IsPhi) {
81    auto *OldPtr =
82        reinterpret_cast<char *>(OldOps + OldNumUses) + sizeof(Use::UserRef);
83    auto *NewPtr =
84        reinterpret_cast<char *>(NewOps + NewNumUses) + sizeof(Use::UserRef);
85    std::copy(OldPtr, OldPtr + (OldNumUses * sizeof(BasicBlock *)), NewPtr);
86  }
87  Use::zap(OldOps, OldOps + OldNumUses, true);
88}
89
90
91// This is a private struct used by `User` to track the co-allocated descriptor
92// section.
93struct DescriptorInfo {
94  intptr_t SizeInBytes;
95};
96
97ArrayRef<const uint8_t> User::getDescriptor() const {
98  auto MutableARef = const_cast<User *>(this)->getDescriptor();
99  return {MutableARef.begin(), MutableARef.end()};
100}
101
102MutableArrayRef<uint8_t> User::getDescriptor() {
103  assert(HasDescriptor && "Don't call otherwise!");
104  assert(!HasHungOffUses && "Invariant!");
105
106  auto *DI = reinterpret_cast<DescriptorInfo *>(getIntrusiveOperands()) - 1;
107  assert(DI->SizeInBytes != 0 && "Should not have had a descriptor otherwise!");
108
109  return MutableArrayRef<uint8_t>(
110      reinterpret_cast<uint8_t *>(DI) - DI->SizeInBytes, DI->SizeInBytes);
111}
112
113//===----------------------------------------------------------------------===//
114//                         User operator new Implementations
115//===----------------------------------------------------------------------===//
116
117void *User::allocateFixedOperandUser(size_t Size, unsigned Us,
118                                     unsigned DescBytes) {
119  assert(Us < (1u << NumUserOperandsBits) && "Too many operands");
120
121  static_assert(sizeof(DescriptorInfo) % sizeof(void *) == 0, "Required below");
122
123  unsigned DescBytesToAllocate =
124      DescBytes == 0 ? 0 : (DescBytes + sizeof(DescriptorInfo));
125  assert(DescBytesToAllocate % sizeof(void *) == 0 &&
126         "We need this to satisfy alignment constraints for Uses");
127
128  uint8_t *Storage = static_cast<uint8_t *>(
129      ::operator new(Size + sizeof(Use) * Us + DescBytesToAllocate));
130  Use *Start = reinterpret_cast<Use *>(Storage + DescBytesToAllocate);
131  Use *End = Start + Us;
132  User *Obj = reinterpret_cast<User*>(End);
133  Obj->NumUserOperands = Us;
134  Obj->HasHungOffUses = false;
135  Obj->HasDescriptor = DescBytes != 0;
136  Use::initTags(Start, End);
137
138  if (DescBytes != 0) {
139    auto *DescInfo = reinterpret_cast<DescriptorInfo *>(Storage + DescBytes);
140    DescInfo->SizeInBytes = DescBytes;
141  }
142
143  return Obj;
144}
145
146void *User::operator new(size_t Size, unsigned Us) {
147  return allocateFixedOperandUser(Size, Us, 0);
148}
149
150void *User::operator new(size_t Size, unsigned Us, unsigned DescBytes) {
151  return allocateFixedOperandUser(Size, Us, DescBytes);
152}
153
154void *User::operator new(size_t Size) {
155  // Allocate space for a single Use*
156  void *Storage = ::operator new(Size + sizeof(Use *));
157  Use **HungOffOperandList = static_cast<Use **>(Storage);
158  User *Obj = reinterpret_cast<User *>(HungOffOperandList + 1);
159  Obj->NumUserOperands = 0;
160  Obj->HasHungOffUses = true;
161  Obj->HasDescriptor = false;
162  *HungOffOperandList = nullptr;
163  return Obj;
164}
165
166//===----------------------------------------------------------------------===//
167//                         User operator delete Implementation
168//===----------------------------------------------------------------------===//
169
170void User::operator delete(void *Usr) {
171  // Hung off uses use a single Use* before the User, while other subclasses
172  // use a Use[] allocated prior to the user.
173  User *Obj = static_cast<User *>(Usr);
174  if (Obj->HasHungOffUses) {
175    assert(!Obj->HasDescriptor && "not supported!");
176
177    Use **HungOffOperandList = static_cast<Use **>(Usr) - 1;
178    // drop the hung off uses.
179    Use::zap(*HungOffOperandList, *HungOffOperandList + Obj->NumUserOperands,
180             /* Delete */ true);
181    ::operator delete(HungOffOperandList);
182  } else if (Obj->HasDescriptor) {
183    Use *UseBegin = static_cast<Use *>(Usr) - Obj->NumUserOperands;
184    Use::zap(UseBegin, UseBegin + Obj->NumUserOperands, /* Delete */ false);
185
186    auto *DI = reinterpret_cast<DescriptorInfo *>(UseBegin) - 1;
187    uint8_t *Storage = reinterpret_cast<uint8_t *>(DI) - DI->SizeInBytes;
188    ::operator delete(Storage);
189  } else {
190    Use *Storage = static_cast<Use *>(Usr) - Obj->NumUserOperands;
191    Use::zap(Storage, Storage + Obj->NumUserOperands,
192             /* Delete */ false);
193    ::operator delete(Storage);
194  }
195}
196
197//===----------------------------------------------------------------------===//
198//                             Operator Class
199//===----------------------------------------------------------------------===//
200
201Operator::~Operator() {
202  llvm_unreachable("should never destroy an Operator");
203}
204
205} // End llvm namespace
206