Bug Summary

File:lib/IR/User.cpp
Warning:line 135, column 5
Potential leak of memory pointed to by 'Storage'

Annotated Source Code

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
14namespace llvm {
15class BasicBlock;
16
17//===----------------------------------------------------------------------===//
18// User Class
19//===----------------------------------------------------------------------===//
20
21void User::replaceUsesOfWith(Value *From, Value *To) {
22 if (From == To) return; // Duh what?
23
24 assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&(static_cast <bool> ((!isa<Constant>(this) || isa
<GlobalValue>(this)) && "Cannot call User::replaceUsesOfWith on a constant!"
) ? void (0) : __assert_fail ("(!isa<Constant>(this) || isa<GlobalValue>(this)) && \"Cannot call User::replaceUsesOfWith on a constant!\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 25, __extension__ __PRETTY_FUNCTION__))
25 "Cannot call User::replaceUsesOfWith on a constant!")(static_cast <bool> ((!isa<Constant>(this) || isa
<GlobalValue>(this)) && "Cannot call User::replaceUsesOfWith on a constant!"
) ? void (0) : __assert_fail ("(!isa<Constant>(this) || isa<GlobalValue>(this)) && \"Cannot call User::replaceUsesOfWith on a constant!\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 25, __extension__ __PRETTY_FUNCTION__))
;
26
27 for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
28 if (getOperand(i) == From) { // Is This operand is pointing to oldval?
29 // The side effects of this setOperand call include linking to
30 // "To", adding "this" to the uses list of To, and
31 // most importantly, removing "this" from the use list of "From".
32 setOperand(i, To); // Fix it now...
33 }
34}
35
36//===----------------------------------------------------------------------===//
37// User allocHungoffUses Implementation
38//===----------------------------------------------------------------------===//
39
40void User::allocHungoffUses(unsigned N, bool IsPhi) {
41 assert(HasHungOffUses && "alloc must have hung off uses")(static_cast <bool> (HasHungOffUses && "alloc must have hung off uses"
) ? void (0) : __assert_fail ("HasHungOffUses && \"alloc must have hung off uses\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 41, __extension__ __PRETTY_FUNCTION__))
;
42
43 static_assert(alignof(Use) >= alignof(Use::UserRef),
44 "Alignment is insufficient for 'hung-off-uses' pieces");
45 static_assert(alignof(Use::UserRef) >= alignof(BasicBlock *),
46 "Alignment is insufficient for 'hung-off-uses' pieces");
47
48 // Allocate the array of Uses, followed by a pointer (with bottom bit set) to
49 // the User.
50 size_t size = N * sizeof(Use) + sizeof(Use::UserRef);
51 if (IsPhi)
52 size += N * sizeof(BasicBlock *);
53 Use *Begin = static_cast<Use*>(::operator new(size));
54 Use *End = Begin + N;
55 (void) new(End) Use::UserRef(const_cast<User*>(this), 1);
56 setOperandList(Use::initTags(Begin, End));
57}
58
59void User::growHungoffUses(unsigned NewNumUses, bool IsPhi) {
60 assert(HasHungOffUses && "realloc must have hung off uses")(static_cast <bool> (HasHungOffUses && "realloc must have hung off uses"
) ? void (0) : __assert_fail ("HasHungOffUses && \"realloc must have hung off uses\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 60, __extension__ __PRETTY_FUNCTION__))
;
61
62 unsigned OldNumUses = getNumOperands();
63
64 // We don't support shrinking the number of uses. We wouldn't have enough
65 // space to copy the old uses in to the new space.
66 assert(NewNumUses > OldNumUses && "realloc must grow num uses")(static_cast <bool> (NewNumUses > OldNumUses &&
"realloc must grow num uses") ? void (0) : __assert_fail ("NewNumUses > OldNumUses && \"realloc must grow num uses\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 66, __extension__ __PRETTY_FUNCTION__))
;
67
68 Use *OldOps = getOperandList();
69 allocHungoffUses(NewNumUses, IsPhi);
70 Use *NewOps = getOperandList();
71
72 // Now copy from the old operands list to the new one.
73 std::copy(OldOps, OldOps + OldNumUses, NewOps);
74
75 // If this is a Phi, then we need to copy the BB pointers too.
76 if (IsPhi) {
77 auto *OldPtr =
78 reinterpret_cast<char *>(OldOps + OldNumUses) + sizeof(Use::UserRef);
79 auto *NewPtr =
80 reinterpret_cast<char *>(NewOps + NewNumUses) + sizeof(Use::UserRef);
81 std::copy(OldPtr, OldPtr + (OldNumUses * sizeof(BasicBlock *)), NewPtr);
82 }
83 Use::zap(OldOps, OldOps + OldNumUses, true);
84}
85
86
87// This is a private struct used by `User` to track the co-allocated descriptor
88// section.
89struct DescriptorInfo {
90 intptr_t SizeInBytes;
91};
92
93ArrayRef<const uint8_t> User::getDescriptor() const {
94 auto MutableARef = const_cast<User *>(this)->getDescriptor();
95 return {MutableARef.begin(), MutableARef.end()};
96}
97
98MutableArrayRef<uint8_t> User::getDescriptor() {
99 assert(HasDescriptor && "Don't call otherwise!")(static_cast <bool> (HasDescriptor && "Don't call otherwise!"
) ? void (0) : __assert_fail ("HasDescriptor && \"Don't call otherwise!\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 99, __extension__ __PRETTY_FUNCTION__))
;
100 assert(!HasHungOffUses && "Invariant!")(static_cast <bool> (!HasHungOffUses && "Invariant!"
) ? void (0) : __assert_fail ("!HasHungOffUses && \"Invariant!\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 100, __extension__ __PRETTY_FUNCTION__))
;
101
102 auto *DI = reinterpret_cast<DescriptorInfo *>(getIntrusiveOperands()) - 1;
103 assert(DI->SizeInBytes != 0 && "Should not have had a descriptor otherwise!")(static_cast <bool> (DI->SizeInBytes != 0 &&
"Should not have had a descriptor otherwise!") ? void (0) : __assert_fail
("DI->SizeInBytes != 0 && \"Should not have had a descriptor otherwise!\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 103, __extension__ __PRETTY_FUNCTION__))
;
104
105 return MutableArrayRef<uint8_t>(
106 reinterpret_cast<uint8_t *>(DI) - DI->SizeInBytes, DI->SizeInBytes);
107}
108
109//===----------------------------------------------------------------------===//
110// User operator new Implementations
111//===----------------------------------------------------------------------===//
112
113void *User::allocateFixedOperandUser(size_t Size, unsigned Us,
114 unsigned DescBytes) {
115 assert(Us < (1u << NumUserOperandsBits) && "Too many operands")(static_cast <bool> (Us < (1u << NumUserOperandsBits
) && "Too many operands") ? void (0) : __assert_fail (
"Us < (1u << NumUserOperandsBits) && \"Too many operands\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 115, __extension__ __PRETTY_FUNCTION__))
;
116
117 static_assert(sizeof(DescriptorInfo) % sizeof(void *) == 0, "Required below");
118
119 unsigned DescBytesToAllocate =
120 DescBytes == 0 ? 0 : (DescBytes + sizeof(DescriptorInfo));
2
Assuming 'DescBytes' is not equal to 0
3
'?' condition is false
121 assert(DescBytesToAllocate % sizeof(void *) == 0 &&(static_cast <bool> (DescBytesToAllocate % sizeof(void *
) == 0 && "We need this to satisfy alignment constraints for Uses"
) ? void (0) : __assert_fail ("DescBytesToAllocate % sizeof(void *) == 0 && \"We need this to satisfy alignment constraints for Uses\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 122, __extension__ __PRETTY_FUNCTION__))
122 "We need this to satisfy alignment constraints for Uses")(static_cast <bool> (DescBytesToAllocate % sizeof(void *
) == 0 && "We need this to satisfy alignment constraints for Uses"
) ? void (0) : __assert_fail ("DescBytesToAllocate % sizeof(void *) == 0 && \"We need this to satisfy alignment constraints for Uses\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 122, __extension__ __PRETTY_FUNCTION__))
;
123
124 uint8_t *Storage = static_cast<uint8_t *>(
125 ::operator new(Size + sizeof(Use) * Us + DescBytesToAllocate));
4
Memory is allocated
126 Use *Start = reinterpret_cast<Use *>(Storage + DescBytesToAllocate);
127 Use *End = Start + Us;
128 User *Obj = reinterpret_cast<User*>(End);
129 Obj->NumUserOperands = Us;
130 Obj->HasHungOffUses = false;
131 Obj->HasDescriptor = DescBytes != 0;
132 Use::initTags(Start, End);
133
134 if (DescBytes != 0) {
5
Taking true branch
135 auto *DescInfo = reinterpret_cast<DescriptorInfo *>(Storage + DescBytes);
6
Potential leak of memory pointed to by 'Storage'
136 DescInfo->SizeInBytes = DescBytes;
137 }
138
139 return Obj;
140}
141
142void *User::operator new(size_t Size, unsigned Us) {
143 return allocateFixedOperandUser(Size, Us, 0);
144}
145
146void *User::operator new(size_t Size, unsigned Us, unsigned DescBytes) {
147 return allocateFixedOperandUser(Size, Us, DescBytes);
1
Calling 'User::allocateFixedOperandUser'
148}
149
150void *User::operator new(size_t Size) {
151 // Allocate space for a single Use*
152 void *Storage = ::operator new(Size + sizeof(Use *));
153 Use **HungOffOperandList = static_cast<Use **>(Storage);
154 User *Obj = reinterpret_cast<User *>(HungOffOperandList + 1);
155 Obj->NumUserOperands = 0;
156 Obj->HasHungOffUses = true;
157 Obj->HasDescriptor = false;
158 *HungOffOperandList = nullptr;
159 return Obj;
160}
161
162//===----------------------------------------------------------------------===//
163// User operator delete Implementation
164//===----------------------------------------------------------------------===//
165
166void User::operator delete(void *Usr) {
167 // Hung off uses use a single Use* before the User, while other subclasses
168 // use a Use[] allocated prior to the user.
169 User *Obj = static_cast<User *>(Usr);
170 if (Obj->HasHungOffUses) {
171 assert(!Obj->HasDescriptor && "not supported!")(static_cast <bool> (!Obj->HasDescriptor && "not supported!"
) ? void (0) : __assert_fail ("!Obj->HasDescriptor && \"not supported!\""
, "/build/llvm-toolchain-snapshot-6.0~svn320940/lib/IR/User.cpp"
, 171, __extension__ __PRETTY_FUNCTION__))
;
172
173 Use **HungOffOperandList = static_cast<Use **>(Usr) - 1;
174 // drop the hung off uses.
175 Use::zap(*HungOffOperandList, *HungOffOperandList + Obj->NumUserOperands,
176 /* Delete */ true);
177 ::operator delete(HungOffOperandList);
178 } else if (Obj->HasDescriptor) {
179 Use *UseBegin = static_cast<Use *>(Usr) - Obj->NumUserOperands;
180 Use::zap(UseBegin, UseBegin + Obj->NumUserOperands, /* Delete */ false);
181
182 auto *DI = reinterpret_cast<DescriptorInfo *>(UseBegin) - 1;
183 uint8_t *Storage = reinterpret_cast<uint8_t *>(DI) - DI->SizeInBytes;
184 ::operator delete(Storage);
185 } else {
186 Use *Storage = static_cast<Use *>(Usr) - Obj->NumUserOperands;
187 Use::zap(Storage, Storage + Obj->NumUserOperands,
188 /* Delete */ false);
189 ::operator delete(Storage);
190 }
191}
192
193} // End llvm namespace