1 //===-- User.cpp - Implement the User class -------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "llvm/IR/User.h" 10 #include "llvm/IR/Constant.h" 11 #include "llvm/IR/GlobalValue.h" 12 #include "llvm/IR/IntrinsicInst.h" 13 14 namespace llvm { 15 class BasicBlock; 16 17 //===----------------------------------------------------------------------===// 18 // User Class 19 //===----------------------------------------------------------------------===// 20 21 void User::replaceUsesOfWith(Value *From, Value *To) { 22 if (From == To) return; // Duh what? 23 24 assert((!isa<Constant>(this) || isa<GlobalValue>(this)) && 25 "Cannot call User::replaceUsesOfWith on a constant!"); 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); 33 } 34 if (auto DVI = dyn_cast_or_null<DbgVariableIntrinsic>(this)) { 35 if (is_contained(DVI->location_ops(), From)) 36 DVI->replaceVariableLocationOp(From, To); 37 } 38 } 39 40 //===----------------------------------------------------------------------===// 41 // User allocHungoffUses Implementation 42 //===----------------------------------------------------------------------===// 43 44 void User::allocHungoffUses(unsigned N, bool IsPhi) { 45 assert(HasHungOffUses && "alloc must have hung off uses"); 46 47 static_assert(alignof(Use) >= alignof(BasicBlock *), 48 "Alignment is insufficient for 'hung-off-uses' pieces"); 49 50 // Allocate the array of Uses 51 size_t size = N * sizeof(Use); 52 if (IsPhi) 53 size += N * sizeof(BasicBlock *); 54 Use *Begin = static_cast<Use*>(::operator new(size)); 55 Use *End = Begin + N; 56 setOperandList(Begin); 57 for (; Begin != End; Begin++) 58 new (Begin) Use(this); 59 } 60 61 void User::growHungoffUses(unsigned NewNumUses, bool IsPhi) { 62 assert(HasHungOffUses && "realloc must have hung off uses"); 63 64 unsigned OldNumUses = getNumOperands(); 65 66 // We don't support shrinking the number of uses. We wouldn't have enough 67 // space to copy the old uses in to the new space. 68 assert(NewNumUses > OldNumUses && "realloc must grow num uses"); 69 70 Use *OldOps = getOperandList(); 71 allocHungoffUses(NewNumUses, IsPhi); 72 Use *NewOps = getOperandList(); 73 74 // Now copy from the old operands list to the new one. 75 std::copy(OldOps, OldOps + OldNumUses, NewOps); 76 77 // If this is a Phi, then we need to copy the BB pointers too. 78 if (IsPhi) { 79 auto *OldPtr = reinterpret_cast<char *>(OldOps + OldNumUses); 80 auto *NewPtr = reinterpret_cast<char *>(NewOps + NewNumUses); 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. 89 struct DescriptorInfo { 90 intptr_t SizeInBytes; 91 }; 92 93 ArrayRef<const uint8_t> User::getDescriptor() const { 94 auto MutableARef = const_cast<User *>(this)->getDescriptor(); 95 return {MutableARef.begin(), MutableARef.end()}; 96 } 97 98 MutableArrayRef<uint8_t> User::getDescriptor() { 99 assert(HasDescriptor && "Don't call otherwise!"); 100 assert(!HasHungOffUses && "Invariant!"); 101 102 auto *DI = reinterpret_cast<DescriptorInfo *>(getIntrusiveOperands()) - 1; 103 assert(DI->SizeInBytes != 0 && "Should not have had a descriptor otherwise!"); 104 105 return MutableArrayRef<uint8_t>( 106 reinterpret_cast<uint8_t *>(DI) - DI->SizeInBytes, DI->SizeInBytes); 107 } 108 109 bool User::isDroppable() const { 110 return isa<AssumeInst>(this) || isa<PseudoProbeInst>(this); 111 } 112 113 //===----------------------------------------------------------------------===// 114 // User operator new Implementations 115 //===----------------------------------------------------------------------===// 116 117 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 for (; Start != End; Start++) 137 new (Start) Use(Obj); 138 139 if (DescBytes != 0) { 140 auto *DescInfo = reinterpret_cast<DescriptorInfo *>(Storage + DescBytes); 141 DescInfo->SizeInBytes = DescBytes; 142 } 143 144 return Obj; 145 } 146 147 void *User::operator new(size_t Size, unsigned Us) { 148 return allocateFixedOperandUser(Size, Us, 0); 149 } 150 151 void *User::operator new(size_t Size, unsigned Us, unsigned DescBytes) { 152 return allocateFixedOperandUser(Size, Us, DescBytes); 153 } 154 155 void *User::operator new(size_t Size) { 156 // Allocate space for a single Use* 157 void *Storage = ::operator new(Size + sizeof(Use *)); 158 Use **HungOffOperandList = static_cast<Use **>(Storage); 159 User *Obj = reinterpret_cast<User *>(HungOffOperandList + 1); 160 Obj->NumUserOperands = 0; 161 Obj->HasHungOffUses = true; 162 Obj->HasDescriptor = false; 163 *HungOffOperandList = nullptr; 164 return Obj; 165 } 166 167 //===----------------------------------------------------------------------===// 168 // User operator delete Implementation 169 //===----------------------------------------------------------------------===// 170 171 // Repress memory sanitization, due to use-after-destroy by operator 172 // delete. Bug report 24578 identifies this issue. 173 LLVM_NO_SANITIZE_MEMORY_ATTRIBUTE void User::operator delete(void *Usr) { 174 // Hung off uses use a single Use* before the User, while other subclasses 175 // use a Use[] allocated prior to the user. 176 User *Obj = static_cast<User *>(Usr); 177 if (Obj->HasHungOffUses) { 178 assert(!Obj->HasDescriptor && "not supported!"); 179 180 Use **HungOffOperandList = static_cast<Use **>(Usr) - 1; 181 // drop the hung off uses. 182 Use::zap(*HungOffOperandList, *HungOffOperandList + Obj->NumUserOperands, 183 /* Delete */ true); 184 ::operator delete(HungOffOperandList); 185 } else if (Obj->HasDescriptor) { 186 Use *UseBegin = static_cast<Use *>(Usr) - Obj->NumUserOperands; 187 Use::zap(UseBegin, UseBegin + Obj->NumUserOperands, /* Delete */ false); 188 189 auto *DI = reinterpret_cast<DescriptorInfo *>(UseBegin) - 1; 190 uint8_t *Storage = reinterpret_cast<uint8_t *>(DI) - DI->SizeInBytes; 191 ::operator delete(Storage); 192 } else { 193 Use *Storage = static_cast<Use *>(Usr) - Obj->NumUserOperands; 194 Use::zap(Storage, Storage + Obj->NumUserOperands, 195 /* Delete */ false); 196 ::operator delete(Storage); 197 } 198 } 199 200 } // namespace llvm 201