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 class BasicBlock;
17
18 //===----------------------------------------------------------------------===//
19 // User Class
20 //===----------------------------------------------------------------------===//
21
anchor()22 void User::anchor() {}
23
replaceUsesOfWith(Value * From,Value * To)24 void 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
allocHungoffUses(unsigned N,bool IsPhi)43 void 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
growHungoffUses(unsigned NewNumUses,bool IsPhi)63 void 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.
93 struct DescriptorInfo {
94 intptr_t SizeInBytes;
95 };
96
getDescriptor() const97 ArrayRef<const uint8_t> User::getDescriptor() const {
98 auto MutableARef = const_cast<User *>(this)->getDescriptor();
99 return {MutableARef.begin(), MutableARef.end()};
100 }
101
getDescriptor()102 MutableArrayRef<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
allocateFixedOperandUser(size_t Size,unsigned Us,unsigned DescBytes)117 void *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
operator new(size_t Size,unsigned Us)146 void *User::operator new(size_t Size, unsigned Us) {
147 return allocateFixedOperandUser(Size, Us, 0);
148 }
149
operator new(size_t Size,unsigned Us,unsigned DescBytes)150 void *User::operator new(size_t Size, unsigned Us, unsigned DescBytes) {
151 return allocateFixedOperandUser(Size, Us, DescBytes);
152 }
153
operator new(size_t Size)154 void *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
operator delete(void * Usr)170 void 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
~Operator()201 Operator::~Operator() {
202 llvm_unreachable("should never destroy an Operator");
203 }
204
205 } // End llvm namespace
206