1 //===- UDTLayout.cpp ------------------------------------------------------===// 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/DebugInfo/PDB/UDTLayout.h" 10 #include "llvm/ADT/ArrayRef.h" 11 #include "llvm/ADT/BitVector.h" 12 #include "llvm/ADT/STLExtras.h" 13 #include "llvm/DebugInfo/PDB/IPDBLineNumber.h" 14 #include "llvm/DebugInfo/PDB/IPDBRawSymbol.h" 15 #include "llvm/DebugInfo/PDB/IPDBSession.h" 16 #include "llvm/DebugInfo/PDB/PDBSymbol.h" 17 #include "llvm/DebugInfo/PDB/PDBSymbolData.h" 18 #include "llvm/DebugInfo/PDB/PDBSymbolFunc.h" 19 #include "llvm/DebugInfo/PDB/PDBSymbolTypeBaseClass.h" 20 #include "llvm/DebugInfo/PDB/PDBSymbolTypeBuiltin.h" 21 #include "llvm/DebugInfo/PDB/PDBSymbolTypeFunctionSig.h" 22 #include "llvm/DebugInfo/PDB/PDBSymbolTypePointer.h" 23 #include "llvm/DebugInfo/PDB/PDBSymbolTypeUDT.h" 24 #include "llvm/DebugInfo/PDB/PDBSymbolTypeVTable.h" 25 #include "llvm/DebugInfo/PDB/PDBTypes.h" 26 #include "llvm/Support/Casting.h" 27 #include <algorithm> 28 #include <cassert> 29 #include <cstdint> 30 #include <memory> 31 32 using namespace llvm; 33 using namespace llvm::pdb; 34 35 static std::unique_ptr<PDBSymbol> getSymbolType(const PDBSymbol &Symbol) { 36 const IPDBSession &Session = Symbol.getSession(); 37 const IPDBRawSymbol &RawSymbol = Symbol.getRawSymbol(); 38 uint32_t TypeId = RawSymbol.getTypeId(); 39 return Session.getSymbolById(TypeId); 40 } 41 42 static uint32_t getTypeLength(const PDBSymbol &Symbol) { 43 auto SymbolType = getSymbolType(Symbol); 44 const IPDBRawSymbol &RawType = SymbolType->getRawSymbol(); 45 46 return RawType.getLength(); 47 } 48 49 LayoutItemBase::LayoutItemBase(const UDTLayoutBase *Parent, 50 const PDBSymbol *Symbol, const std::string &Name, 51 uint32_t OffsetInParent, uint32_t Size, 52 bool IsElided) 53 : Symbol(Symbol), Parent(Parent), Name(Name), 54 OffsetInParent(OffsetInParent), SizeOf(Size), LayoutSize(Size), 55 IsElided(IsElided) { 56 UsedBytes.resize(SizeOf, true); 57 } 58 59 uint32_t LayoutItemBase::deepPaddingSize() const { 60 return UsedBytes.size() - UsedBytes.count(); 61 } 62 63 uint32_t LayoutItemBase::tailPadding() const { 64 int Last = UsedBytes.find_last(); 65 66 return UsedBytes.size() - (Last + 1); 67 } 68 69 DataMemberLayoutItem::DataMemberLayoutItem( 70 const UDTLayoutBase &Parent, std::unique_ptr<PDBSymbolData> Member) 71 : LayoutItemBase(&Parent, Member.get(), Member->getName(), 72 Member->getOffset(), getTypeLength(*Member), false), 73 DataMember(std::move(Member)) { 74 auto Type = DataMember->getType(); 75 if (auto UDT = unique_dyn_cast<PDBSymbolTypeUDT>(Type)) { 76 UdtLayout = std::make_unique<ClassLayout>(std::move(UDT)); 77 UsedBytes = UdtLayout->usedBytes(); 78 } 79 } 80 81 VBPtrLayoutItem::VBPtrLayoutItem(const UDTLayoutBase &Parent, 82 std::unique_ptr<PDBSymbolTypeBuiltin> Sym, 83 uint32_t Offset, uint32_t Size) 84 : LayoutItemBase(&Parent, Sym.get(), "<vbptr>", Offset, Size, false), 85 Type(std::move(Sym)) { 86 } 87 88 const PDBSymbolData &DataMemberLayoutItem::getDataMember() { 89 return *cast<PDBSymbolData>(Symbol); 90 } 91 92 bool DataMemberLayoutItem::hasUDTLayout() const { return UdtLayout != nullptr; } 93 94 const ClassLayout &DataMemberLayoutItem::getUDTLayout() const { 95 return *UdtLayout; 96 } 97 98 VTableLayoutItem::VTableLayoutItem(const UDTLayoutBase &Parent, 99 std::unique_ptr<PDBSymbolTypeVTable> VT) 100 : LayoutItemBase(&Parent, VT.get(), "<vtbl>", 0, getTypeLength(*VT), false), 101 VTable(std::move(VT)) { 102 auto VTableType = cast<PDBSymbolTypePointer>(VTable->getType()); 103 ElementSize = VTableType->getLength(); 104 } 105 106 UDTLayoutBase::UDTLayoutBase(const UDTLayoutBase *Parent, const PDBSymbol &Sym, 107 const std::string &Name, uint32_t OffsetInParent, 108 uint32_t Size, bool IsElided) 109 : LayoutItemBase(Parent, &Sym, Name, OffsetInParent, Size, IsElided) { 110 // UDT storage comes from a union of all the children's storage, so start out 111 // uninitialized. 112 UsedBytes.reset(0, Size); 113 114 initializeChildren(Sym); 115 if (LayoutSize < Size) 116 UsedBytes.resize(LayoutSize); 117 } 118 119 uint32_t UDTLayoutBase::tailPadding() const { 120 uint32_t Abs = LayoutItemBase::tailPadding(); 121 if (!LayoutItems.empty()) { 122 const LayoutItemBase *Back = LayoutItems.back(); 123 uint32_t ChildPadding = Back->LayoutItemBase::tailPadding(); 124 if (Abs < ChildPadding) 125 Abs = 0; 126 else 127 Abs -= ChildPadding; 128 } 129 return Abs; 130 } 131 132 ClassLayout::ClassLayout(const PDBSymbolTypeUDT &UDT) 133 : UDTLayoutBase(nullptr, UDT, UDT.getName(), 0, UDT.getLength(), false), 134 UDT(UDT) { 135 ImmediateUsedBytes.resize(SizeOf, false); 136 for (auto &LI : LayoutItems) { 137 uint32_t Begin = LI->getOffsetInParent(); 138 uint32_t End = Begin + LI->getLayoutSize(); 139 End = std::min(SizeOf, End); 140 ImmediateUsedBytes.set(Begin, End); 141 } 142 } 143 144 ClassLayout::ClassLayout(std::unique_ptr<PDBSymbolTypeUDT> UDT) 145 : ClassLayout(*UDT) { 146 OwnedStorage = std::move(UDT); 147 } 148 149 uint32_t ClassLayout::immediatePadding() const { 150 return SizeOf - ImmediateUsedBytes.count(); 151 } 152 153 BaseClassLayout::BaseClassLayout(const UDTLayoutBase &Parent, 154 uint32_t OffsetInParent, bool Elide, 155 std::unique_ptr<PDBSymbolTypeBaseClass> B) 156 : UDTLayoutBase(&Parent, *B, B->getName(), OffsetInParent, B->getLength(), 157 Elide), 158 Base(std::move(B)) { 159 if (isEmptyBase()) { 160 // Special case an empty base so that it doesn't get treated as padding. 161 UsedBytes.resize(1); 162 UsedBytes.set(0); 163 } 164 IsVirtualBase = Base->isVirtualBaseClass(); 165 } 166 167 void UDTLayoutBase::initializeChildren(const PDBSymbol &Sym) { 168 // Handled bases first, followed by VTables, followed by data members, 169 // followed by functions, followed by other. This ordering is necessary 170 // so that bases and vtables get initialized before any functions which 171 // may override them. 172 UniquePtrVector<PDBSymbolTypeBaseClass> Bases; 173 UniquePtrVector<PDBSymbolTypeVTable> VTables; 174 UniquePtrVector<PDBSymbolData> Members; 175 UniquePtrVector<PDBSymbolTypeBaseClass> VirtualBaseSyms; 176 177 auto Children = Sym.findAllChildren(); 178 while (auto Child = Children->getNext()) { 179 if (auto Base = unique_dyn_cast<PDBSymbolTypeBaseClass>(Child)) { 180 if (Base->isVirtualBaseClass()) 181 VirtualBaseSyms.push_back(std::move(Base)); 182 else 183 Bases.push_back(std::move(Base)); 184 } 185 else if (auto Data = unique_dyn_cast<PDBSymbolData>(Child)) { 186 if (Data->getDataKind() == PDB_DataKind::Member) 187 Members.push_back(std::move(Data)); 188 else 189 Other.push_back(std::move(Data)); 190 } else if (auto VT = unique_dyn_cast<PDBSymbolTypeVTable>(Child)) 191 VTables.push_back(std::move(VT)); 192 else if (auto Func = unique_dyn_cast<PDBSymbolFunc>(Child)) 193 Funcs.push_back(std::move(Func)); 194 else { 195 Other.push_back(std::move(Child)); 196 } 197 } 198 199 // We don't want to have any re-allocations in the list of bases, so make 200 // sure to reserve enough space so that our ArrayRefs don't get invalidated. 201 AllBases.reserve(Bases.size() + VirtualBaseSyms.size()); 202 203 // Only add non-virtual bases to the class first. Only at the end of the 204 // class, after all non-virtual bases and data members have been added do we 205 // add virtual bases. This way the offsets are correctly aligned when we go 206 // to lay out virtual bases. 207 for (auto &Base : Bases) { 208 uint32_t Offset = Base->getOffset(); 209 // Non-virtual bases never get elided. 210 auto BL = std::make_unique<BaseClassLayout>(*this, Offset, false, 211 std::move(Base)); 212 213 AllBases.push_back(BL.get()); 214 addChildToLayout(std::move(BL)); 215 } 216 NonVirtualBases = AllBases; 217 218 assert(VTables.size() <= 1); 219 if (!VTables.empty()) { 220 auto VTLayout = 221 std::make_unique<VTableLayoutItem>(*this, std::move(VTables[0])); 222 223 VTable = VTLayout.get(); 224 225 addChildToLayout(std::move(VTLayout)); 226 } 227 228 for (auto &Data : Members) { 229 auto DM = std::make_unique<DataMemberLayoutItem>(*this, std::move(Data)); 230 231 addChildToLayout(std::move(DM)); 232 } 233 234 // Make sure add virtual bases before adding functions, since functions may be 235 // overrides of virtual functions declared in a virtual base, so the VTables 236 // and virtual intros need to be correctly initialized. 237 for (auto &VB : VirtualBaseSyms) { 238 int VBPO = VB->getVirtualBasePointerOffset(); 239 if (!hasVBPtrAtOffset(VBPO)) { 240 if (auto VBP = VB->getRawSymbol().getVirtualBaseTableType()) { 241 auto VBPL = std::make_unique<VBPtrLayoutItem>(*this, std::move(VBP), 242 VBPO, VBP->getLength()); 243 VBPtr = VBPL.get(); 244 addChildToLayout(std::move(VBPL)); 245 } 246 } 247 248 // Virtual bases always go at the end. So just look for the last place we 249 // ended when writing something, and put our virtual base there. 250 // Note that virtual bases get elided unless this is a top-most derived 251 // class. 252 uint32_t Offset = UsedBytes.find_last() + 1; 253 bool Elide = (Parent != nullptr); 254 auto BL = 255 std::make_unique<BaseClassLayout>(*this, Offset, Elide, std::move(VB)); 256 AllBases.push_back(BL.get()); 257 258 // Only lay this virtual base out directly inside of *this* class if this 259 // is a top-most derived class. Keep track of it regardless, but only 260 // physically lay it out if it's a topmost derived class. 261 addChildToLayout(std::move(BL)); 262 } 263 VirtualBases = makeArrayRef(AllBases).drop_front(NonVirtualBases.size()); 264 265 if (Parent != nullptr) 266 LayoutSize = UsedBytes.find_last() + 1; 267 } 268 269 bool UDTLayoutBase::hasVBPtrAtOffset(uint32_t Off) const { 270 if (VBPtr && VBPtr->getOffsetInParent() == Off) 271 return true; 272 for (BaseClassLayout *BL : AllBases) { 273 if (BL->hasVBPtrAtOffset(Off - BL->getOffsetInParent())) 274 return true; 275 } 276 return false; 277 } 278 279 void UDTLayoutBase::addChildToLayout(std::unique_ptr<LayoutItemBase> Child) { 280 uint32_t Begin = Child->getOffsetInParent(); 281 282 if (!Child->isElided()) { 283 BitVector ChildBytes = Child->usedBytes(); 284 285 // Suppose the child occupies 4 bytes starting at offset 12 in a 32 byte 286 // class. When we call ChildBytes.resize(32), the Child's storage will 287 // still begin at offset 0, so we need to shift it left by offset bytes 288 // to get it into the right position. 289 ChildBytes.resize(UsedBytes.size()); 290 ChildBytes <<= Child->getOffsetInParent(); 291 UsedBytes |= ChildBytes; 292 293 if (ChildBytes.count() > 0) { 294 auto Loc = llvm::upper_bound( 295 LayoutItems, Begin, [](uint32_t Off, const LayoutItemBase *Item) { 296 return (Off < Item->getOffsetInParent()); 297 }); 298 299 LayoutItems.insert(Loc, Child.get()); 300 } 301 } 302 303 ChildStorage.push_back(std::move(Child)); 304 } 305