1 //===- UDTLayout.cpp --------------------------------------------*- C++ -*-===// 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/DebugInfo/PDB/UDTLayout.h" 11 12 #include "llvm/ADT/STLExtras.h" 13 #include "llvm/DebugInfo/PDB/IPDBSession.h" 14 #include "llvm/DebugInfo/PDB/PDBSymbol.h" 15 #include "llvm/DebugInfo/PDB/PDBSymbolData.h" 16 #include "llvm/DebugInfo/PDB/PDBSymbolExe.h" 17 #include "llvm/DebugInfo/PDB/PDBSymbolFunc.h" 18 #include "llvm/DebugInfo/PDB/PDBSymbolTypeBaseClass.h" 19 #include "llvm/DebugInfo/PDB/PDBSymbolTypeBuiltin.h" 20 #include "llvm/DebugInfo/PDB/PDBSymbolTypePointer.h" 21 #include "llvm/DebugInfo/PDB/PDBSymbolTypeUDT.h" 22 #include "llvm/DebugInfo/PDB/PDBSymbolTypeVTable.h" 23 24 #include <utility> 25 26 using namespace llvm; 27 using namespace llvm::pdb; 28 29 static std::unique_ptr<PDBSymbol> getSymbolType(const PDBSymbol &Symbol) { 30 const IPDBSession &Session = Symbol.getSession(); 31 const IPDBRawSymbol &RawSymbol = Symbol.getRawSymbol(); 32 uint32_t TypeId = RawSymbol.getTypeId(); 33 return Session.getSymbolById(TypeId); 34 } 35 36 static uint32_t getTypeLength(const PDBSymbol &Symbol) { 37 auto SymbolType = getSymbolType(Symbol); 38 const IPDBRawSymbol &RawType = SymbolType->getRawSymbol(); 39 40 return RawType.getLength(); 41 } 42 43 LayoutItemBase::LayoutItemBase(const UDTLayoutBase *Parent, 44 const PDBSymbol *Symbol, const std::string &Name, 45 uint32_t OffsetInParent, uint32_t Size, 46 bool IsElided) 47 : Symbol(Symbol), Parent(Parent), Name(Name), 48 OffsetInParent(OffsetInParent), SizeOf(Size), LayoutSize(Size), 49 IsElided(IsElided) { 50 UsedBytes.resize(SizeOf, true); 51 } 52 53 uint32_t LayoutItemBase::deepPaddingSize() const { 54 return UsedBytes.size() - UsedBytes.count(); 55 } 56 57 uint32_t LayoutItemBase::tailPadding() const { 58 int Last = UsedBytes.find_last(); 59 60 return UsedBytes.size() - (Last + 1); 61 } 62 63 64 DataMemberLayoutItem::DataMemberLayoutItem( 65 const UDTLayoutBase &Parent, std::unique_ptr<PDBSymbolData> Member) 66 : LayoutItemBase(&Parent, Member.get(), Member->getName(), 67 Member->getOffset(), getTypeLength(*Member), false), 68 DataMember(std::move(Member)) { 69 auto Type = DataMember->getType(); 70 if (auto UDT = unique_dyn_cast<PDBSymbolTypeUDT>(Type)) { 71 UdtLayout = llvm::make_unique<ClassLayout>(std::move(UDT)); 72 UsedBytes = UdtLayout->usedBytes(); 73 } 74 } 75 76 VBPtrLayoutItem::VBPtrLayoutItem(const UDTLayoutBase &Parent, 77 std::unique_ptr<PDBSymbolTypeBuiltin> Sym, 78 uint32_t Offset, uint32_t Size) 79 : LayoutItemBase(&Parent, Sym.get(), "<vbptr>", Offset, Size, false), 80 Type(std::move(Sym)) { 81 } 82 83 const PDBSymbolData &DataMemberLayoutItem::getDataMember() { 84 return *dyn_cast<PDBSymbolData>(Symbol); 85 } 86 87 bool DataMemberLayoutItem::hasUDTLayout() const { return UdtLayout != nullptr; } 88 89 const ClassLayout &DataMemberLayoutItem::getUDTLayout() const { 90 return *UdtLayout; 91 } 92 93 VTableLayoutItem::VTableLayoutItem(const UDTLayoutBase &Parent, 94 std::unique_ptr<PDBSymbolTypeVTable> VT) 95 : LayoutItemBase(&Parent, VT.get(), "<vtbl>", 0, getTypeLength(*VT), false), 96 VTable(std::move(VT)) { 97 auto VTableType = cast<PDBSymbolTypePointer>(VTable->getType()); 98 ElementSize = VTableType->getLength(); 99 } 100 101 UDTLayoutBase::UDTLayoutBase(const UDTLayoutBase *Parent, const PDBSymbol &Sym, 102 const std::string &Name, uint32_t OffsetInParent, 103 uint32_t Size, bool IsElided) 104 : LayoutItemBase(Parent, &Sym, Name, OffsetInParent, Size, IsElided) { 105 // UDT storage comes from a union of all the children's storage, so start out 106 // uninitialized. 107 UsedBytes.reset(0, Size); 108 109 initializeChildren(Sym); 110 if (LayoutSize < Size) 111 UsedBytes.resize(LayoutSize); 112 } 113 114 uint32_t UDTLayoutBase::tailPadding() const { 115 uint32_t Abs = LayoutItemBase::tailPadding(); 116 if (!LayoutItems.empty()) { 117 const LayoutItemBase *Back = LayoutItems.back(); 118 uint32_t ChildPadding = Back->LayoutItemBase::tailPadding(); 119 if (Abs < ChildPadding) 120 Abs = 0; 121 else 122 Abs -= ChildPadding; 123 } 124 return Abs; 125 } 126 127 ClassLayout::ClassLayout(const PDBSymbolTypeUDT &UDT) 128 : UDTLayoutBase(nullptr, UDT, UDT.getName(), 0, UDT.getLength(), false), 129 UDT(UDT) {} 130 131 ClassLayout::ClassLayout(std::unique_ptr<PDBSymbolTypeUDT> UDT) 132 : ClassLayout(*UDT) { 133 OwnedStorage = std::move(UDT); 134 } 135 136 BaseClassLayout::BaseClassLayout(const UDTLayoutBase &Parent, 137 uint32_t OffsetInParent, bool Elide, 138 std::unique_ptr<PDBSymbolTypeBaseClass> B) 139 : UDTLayoutBase(&Parent, *B, B->getName(), OffsetInParent, B->getLength(), 140 Elide), 141 Base(std::move(B)) { 142 if (isEmptyBase()) { 143 // Special case an empty base so that it doesn't get treated as padding. 144 UsedBytes.resize(1); 145 UsedBytes.set(0); 146 } 147 IsVirtualBase = Base->isVirtualBaseClass(); 148 } 149 150 void UDTLayoutBase::initializeChildren(const PDBSymbol &Sym) { 151 // Handled bases first, followed by VTables, followed by data members, 152 // followed by functions, followed by other. This ordering is necessary 153 // so that bases and vtables get initialized before any functions which 154 // may override them. 155 UniquePtrVector<PDBSymbolTypeBaseClass> Bases; 156 UniquePtrVector<PDBSymbolTypeVTable> VTables; 157 UniquePtrVector<PDBSymbolData> Members; 158 UniquePtrVector<PDBSymbolTypeBaseClass> VirtualBaseSyms; 159 160 auto Children = Sym.findAllChildren(); 161 while (auto Child = Children->getNext()) { 162 if (auto Base = unique_dyn_cast<PDBSymbolTypeBaseClass>(Child)) { 163 if (Base->isVirtualBaseClass()) 164 VirtualBaseSyms.push_back(std::move(Base)); 165 else 166 Bases.push_back(std::move(Base)); 167 } 168 169 else if (auto Data = unique_dyn_cast<PDBSymbolData>(Child)) { 170 if (Data->getDataKind() == PDB_DataKind::Member) 171 Members.push_back(std::move(Data)); 172 else 173 Other.push_back(std::move(Child)); 174 } else if (auto VT = unique_dyn_cast<PDBSymbolTypeVTable>(Child)) 175 VTables.push_back(std::move(VT)); 176 else if (auto Func = unique_dyn_cast<PDBSymbolFunc>(Child)) 177 Funcs.push_back(std::move(Func)); 178 else 179 Other.push_back(std::move(Child)); 180 } 181 182 // We don't want to have any re-allocations in the list of bases, so make 183 // sure to reserve enough space so that our ArrayRefs don't get invalidated. 184 AllBases.reserve(Bases.size() + VirtualBaseSyms.size()); 185 186 // Only add non-virtual bases to the class first. Only at the end of the 187 // class, after all non-virtual bases and data members have been added do we 188 // add virtual bases. This way the offsets are correctly aligned when we go 189 // to lay out virtual bases. 190 for (auto &Base : Bases) { 191 uint32_t Offset = Base->getOffset(); 192 // Non-virtual bases never get elided. 193 auto BL = llvm::make_unique<BaseClassLayout>(*this, Offset, false, 194 std::move(Base)); 195 196 AllBases.push_back(BL.get()); 197 addChildToLayout(std::move(BL)); 198 } 199 NonVirtualBases = AllBases; 200 201 assert(VTables.size() <= 1); 202 if (!VTables.empty()) { 203 auto VTLayout = 204 llvm::make_unique<VTableLayoutItem>(*this, std::move(VTables[0])); 205 206 VTable = VTLayout.get(); 207 208 addChildToLayout(std::move(VTLayout)); 209 } 210 211 for (auto &Data : Members) { 212 auto DM = llvm::make_unique<DataMemberLayoutItem>(*this, std::move(Data)); 213 214 addChildToLayout(std::move(DM)); 215 } 216 217 // Make sure add virtual bases before adding functions, since functions may be 218 // overrides of virtual functions declared in a virtual base, so the VTables 219 // and virtual intros need to be correctly initialized. 220 for (auto &VB : VirtualBaseSyms) { 221 int VBPO = VB->getVirtualBasePointerOffset(); 222 if (!hasVBPtrAtOffset(VBPO)) { 223 if (auto VBP = VB->getRawSymbol().getVirtualBaseTableType()) { 224 auto VBPL = llvm::make_unique<VBPtrLayoutItem>(*this, std::move(VBP), 225 VBPO, VBP->getLength()); 226 VBPtr = VBPL.get(); 227 addChildToLayout(std::move(VBPL)); 228 } 229 } 230 231 // Virtual bases always go at the end. So just look for the last place we 232 // ended when writing something, and put our virtual base there. 233 // Note that virtual bases get elided unless this is a top-most derived 234 // class. 235 uint32_t Offset = UsedBytes.find_last() + 1; 236 bool Elide = (Parent != nullptr); 237 auto BL = 238 llvm::make_unique<BaseClassLayout>(*this, Offset, Elide, std::move(VB)); 239 AllBases.push_back(BL.get()); 240 241 // Only lay this virtual base out directly inside of *this* class if this 242 // is a top-most derived class. Keep track of it regardless, but only 243 // physically lay it out if it's a topmost derived class. 244 addChildToLayout(std::move(BL)); 245 } 246 VirtualBases = makeArrayRef(AllBases).drop_front(NonVirtualBases.size()); 247 248 if (Parent != nullptr) 249 LayoutSize = UsedBytes.find_last() + 1; 250 } 251 252 bool UDTLayoutBase::hasVBPtrAtOffset(uint32_t Off) const { 253 if (VBPtr && VBPtr->getOffsetInParent() == Off) 254 return true; 255 for (BaseClassLayout *BL : AllBases) { 256 if (BL->hasVBPtrAtOffset(Off - BL->getOffsetInParent())) 257 return true; 258 } 259 return false; 260 } 261 262 void UDTLayoutBase::addChildToLayout(std::unique_ptr<LayoutItemBase> Child) { 263 uint32_t Begin = Child->getOffsetInParent(); 264 265 if (!Child->isElided()) { 266 BitVector ChildBytes = Child->usedBytes(); 267 268 // Suppose the child occupies 4 bytes starting at offset 12 in a 32 byte 269 // class. When we call ChildBytes.resize(32), the Child's storage will 270 // still begin at offset 0, so we need to shift it left by offset bytes 271 // to get it into the right position. 272 ChildBytes.resize(UsedBytes.size()); 273 ChildBytes <<= Child->getOffsetInParent(); 274 UsedBytes |= ChildBytes; 275 276 if (ChildBytes.count() > 0) { 277 auto Loc = std::upper_bound(LayoutItems.begin(), LayoutItems.end(), Begin, 278 [](uint32_t Off, const LayoutItemBase *Item) { 279 return (Off < Item->getOffsetInParent()); 280 }); 281 282 LayoutItems.insert(Loc, Child.get()); 283 } 284 } 285 286 ChildStorage.push_back(std::move(Child)); 287 }