1 files changed, 302 insertions, 0 deletions
diff --git a/llvm/lib/DebugInfo/PDB/UDTLayout.cpp b/llvm/lib/DebugInfo/PDB/UDTLayout.cpp
new file mode 100644
index 0000000000000..a8e1d0a619cab
--- /dev/null
+++ b/llvm/lib/DebugInfo/PDB/UDTLayout.cpp
@@ -0,0 +1,302 @@
+//===- UDTLayout.cpp ------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/PDB/UDTLayout.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/DebugInfo/PDB/IPDBRawSymbol.h"
+#include "llvm/DebugInfo/PDB/IPDBSession.h"
+#include "llvm/DebugInfo/PDB/PDBSymbol.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolData.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolFunc.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolTypeBaseClass.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolTypeBuiltin.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolTypePointer.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolTypeUDT.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolTypeVTable.h"
+#include "llvm/DebugInfo/PDB/PDBTypes.h"
+#include "llvm/Support/Casting.h"
+#include <algorithm>
+#include <cassert>
+#include <cstdint>
+#include <memory>
+
+using namespace llvm;
+using namespace llvm::pdb;
+
+static std::unique_ptr<PDBSymbol> getSymbolType(const PDBSymbol &Symbol) {
+  const IPDBSession &Session = Symbol.getSession();
+  const IPDBRawSymbol &RawSymbol = Symbol.getRawSymbol();
+  uint32_t TypeId = RawSymbol.getTypeId();
+  return Session.getSymbolById(TypeId);
+}
+
+static uint32_t getTypeLength(const PDBSymbol &Symbol) {
+  auto SymbolType = getSymbolType(Symbol);
+  const IPDBRawSymbol &RawType = SymbolType->getRawSymbol();
+
+  return RawType.getLength();
+}
+
+LayoutItemBase::LayoutItemBase(const UDTLayoutBase *Parent,
+                               const PDBSymbol *Symbol, const std::string &Name,
+                               uint32_t OffsetInParent, uint32_t Size,
+                               bool IsElided)
+    : Symbol(Symbol), Parent(Parent), Name(Name),
+      OffsetInParent(OffsetInParent), SizeOf(Size), LayoutSize(Size),
+      IsElided(IsElided) {
+  UsedBytes.resize(SizeOf, true);
+}
+
+uint32_t LayoutItemBase::deepPaddingSize() const {
+  return UsedBytes.size() - UsedBytes.count();
+}
+
+uint32_t LayoutItemBase::tailPadding() const {
+  int Last = UsedBytes.find_last();
+
+  return UsedBytes.size() - (Last + 1);
+}
+
+DataMemberLayoutItem::DataMemberLayoutItem(
+    const UDTLayoutBase &Parent, std::unique_ptr<PDBSymbolData> Member)
+    : LayoutItemBase(&Parent, Member.get(), Member->getName(),
+                     Member->getOffset(), getTypeLength(*Member), false),
+      DataMember(std::move(Member)) {
+  auto Type = DataMember->getType();
+  if (auto UDT = unique_dyn_cast<PDBSymbolTypeUDT>(Type)) {
+    UdtLayout = std::make_unique<ClassLayout>(std::move(UDT));
+    UsedBytes = UdtLayout->usedBytes();
+  }
+}
+
+VBPtrLayoutItem::VBPtrLayoutItem(const UDTLayoutBase &Parent,
+                                 std::unique_ptr<PDBSymbolTypeBuiltin> Sym,
+                                 uint32_t Offset, uint32_t Size)
+    : LayoutItemBase(&Parent, Sym.get(), "<vbptr>", Offset, Size, false),
+      Type(std::move(Sym)) {
+}
+
+const PDBSymbolData &DataMemberLayoutItem::getDataMember() {
+  return *cast<PDBSymbolData>(Symbol);
+}
+
+bool DataMemberLayoutItem::hasUDTLayout() const { return UdtLayout != nullptr; }
+
+const ClassLayout &DataMemberLayoutItem::getUDTLayout() const {
+  return *UdtLayout;
+}
+
+VTableLayoutItem::VTableLayoutItem(const UDTLayoutBase &Parent,
+                                   std::unique_ptr<PDBSymbolTypeVTable> VT)
+    : LayoutItemBase(&Parent, VT.get(), "<vtbl>", 0, getTypeLength(*VT), false),
+      VTable(std::move(VT)) {
+  auto VTableType = cast<PDBSymbolTypePointer>(VTable->getType());
+  ElementSize = VTableType->getLength();
+}
+
+UDTLayoutBase::UDTLayoutBase(const UDTLayoutBase *Parent, const PDBSymbol &Sym,
+                             const std::string &Name, uint32_t OffsetInParent,
+                             uint32_t Size, bool IsElided)
+    : LayoutItemBase(Parent, &Sym, Name, OffsetInParent, Size, IsElided) {
+  // UDT storage comes from a union of all the children's storage, so start out
+  // uninitialized.
+  UsedBytes.reset(0, Size);
+
+  initializeChildren(Sym);
+  if (LayoutSize < Size)
+    UsedBytes.resize(LayoutSize);
+}
+
+uint32_t UDTLayoutBase::tailPadding() const {
+  uint32_t Abs = LayoutItemBase::tailPadding();
+  if (!LayoutItems.empty()) {
+    const LayoutItemBase *Back = LayoutItems.back();
+    uint32_t ChildPadding = Back->LayoutItemBase::tailPadding();
+    if (Abs < ChildPadding)
+      Abs = 0;
+    else
+      Abs -= ChildPadding;
+  }
+  return Abs;
+}
+
+ClassLayout::ClassLayout(const PDBSymbolTypeUDT &UDT)
+    : UDTLayoutBase(nullptr, UDT, UDT.getName(), 0, UDT.getLength(), false),
+      UDT(UDT) {
+  ImmediateUsedBytes.resize(SizeOf, false);
+  for (auto &LI : LayoutItems) {
+    uint32_t Begin = LI->getOffsetInParent();
+    uint32_t End = Begin + LI->getLayoutSize();
+    End = std::min(SizeOf, End);
+    ImmediateUsedBytes.set(Begin, End);
+  }
+}
+
+ClassLayout::ClassLayout(std::unique_ptr<PDBSymbolTypeUDT> UDT)
+    : ClassLayout(*UDT) {
+  OwnedStorage = std::move(UDT);
+}
+
+uint32_t ClassLayout::immediatePadding() const {
+  return SizeOf - ImmediateUsedBytes.count();
+}
+
+BaseClassLayout::BaseClassLayout(const UDTLayoutBase &Parent,
+                                 uint32_t OffsetInParent, bool Elide,
+                                 std::unique_ptr<PDBSymbolTypeBaseClass> B)
+    : UDTLayoutBase(&Parent, *B, B->getName(), OffsetInParent, B->getLength(),
+                    Elide),
+      Base(std::move(B)) {
+  if (isEmptyBase()) {
+    // Special case an empty base so that it doesn't get treated as padding.
+    UsedBytes.resize(1);
+    UsedBytes.set(0);
+  }
+  IsVirtualBase = Base->isVirtualBaseClass();
+}
+
+void UDTLayoutBase::initializeChildren(const PDBSymbol &Sym) {
+  // Handled bases first, followed by VTables, followed by data members,
+  // followed by functions, followed by other.  This ordering is necessary
+  // so that bases and vtables get initialized before any functions which
+  // may override them.
+  UniquePtrVector<PDBSymbolTypeBaseClass> Bases;
+  UniquePtrVector<PDBSymbolTypeVTable> VTables;
+  UniquePtrVector<PDBSymbolData> Members;
+  UniquePtrVector<PDBSymbolTypeBaseClass> VirtualBaseSyms;
+
+  auto Children = Sym.findAllChildren();
+  while (auto Child = Children->getNext()) {
+    if (auto Base = unique_dyn_cast<PDBSymbolTypeBaseClass>(Child)) {
+      if (Base->isVirtualBaseClass())
+        VirtualBaseSyms.push_back(std::move(Base));
+      else
+        Bases.push_back(std::move(Base));
+    }
+    else if (auto Data = unique_dyn_cast<PDBSymbolData>(Child)) {
+      if (Data->getDataKind() == PDB_DataKind::Member)
+        Members.push_back(std::move(Data));
+      else
+        Other.push_back(std::move(Data));
+    } else if (auto VT = unique_dyn_cast<PDBSymbolTypeVTable>(Child))
+      VTables.push_back(std::move(VT));
+    else if (auto Func = unique_dyn_cast<PDBSymbolFunc>(Child))
+      Funcs.push_back(std::move(Func));
+    else {
+      Other.push_back(std::move(Child));
+    }
+  }
+
+  // We don't want to have any re-allocations in the list of bases, so make
+  // sure to reserve enough space so that our ArrayRefs don't get invalidated.
+  AllBases.reserve(Bases.size() + VirtualBaseSyms.size());
+
+  // Only add non-virtual bases to the class first.  Only at the end of the
+  // class, after all non-virtual bases and data members have been added do we
+  // add virtual bases.  This way the offsets are correctly aligned when we go
+  // to lay out virtual bases.
+  for (auto &Base : Bases) {
+    uint32_t Offset = Base->getOffset();
+    // Non-virtual bases never get elided.
+    auto BL = std::make_unique<BaseClassLayout>(*this, Offset, false,
+                                                 std::move(Base));
+
+    AllBases.push_back(BL.get());
+    addChildToLayout(std::move(BL));
+  }
+  NonVirtualBases = AllBases;
+
+  assert(VTables.size() <= 1);
+  if (!VTables.empty()) {
+    auto VTLayout =
+        std::make_unique<VTableLayoutItem>(*this, std::move(VTables[0]));
+
+    VTable = VTLayout.get();
+
+    addChildToLayout(std::move(VTLayout));
+  }
+
+  for (auto &Data : Members) {
+    auto DM = std::make_unique<DataMemberLayoutItem>(*this, std::move(Data));
+
+    addChildToLayout(std::move(DM));
+  }
+
+  // Make sure add virtual bases before adding functions, since functions may be
+  // overrides of virtual functions declared in a virtual base, so the VTables
+  // and virtual intros need to be correctly initialized.
+  for (auto &VB : VirtualBaseSyms) {
+    int VBPO = VB->getVirtualBasePointerOffset();
+    if (!hasVBPtrAtOffset(VBPO)) {
+      if (auto VBP = VB->getRawSymbol().getVirtualBaseTableType()) {
+        auto VBPL = std::make_unique<VBPtrLayoutItem>(*this, std::move(VBP),
+                                                       VBPO, VBP->getLength());
+        VBPtr = VBPL.get();
+        addChildToLayout(std::move(VBPL));
+      }
+    }
+
+    // Virtual bases always go at the end.  So just look for the last place we
+    // ended when writing something, and put our virtual base there.
+    // Note that virtual bases get elided unless this is a top-most derived
+    // class.
+    uint32_t Offset = UsedBytes.find_last() + 1;
+    bool Elide = (Parent != nullptr);
+    auto BL =
+        std::make_unique<BaseClassLayout>(*this, Offset, Elide, std::move(VB));
+    AllBases.push_back(BL.get());
+
+    // Only lay this virtual base out directly inside of *this* class if this
+    // is a top-most derived class.  Keep track of it regardless, but only
+    // physically lay it out if it's a topmost derived class.
+    addChildToLayout(std::move(BL));
+  }
+  VirtualBases = makeArrayRef(AllBases).drop_front(NonVirtualBases.size());
+
+  if (Parent != nullptr)
+    LayoutSize = UsedBytes.find_last() + 1;
+}
+
+bool UDTLayoutBase::hasVBPtrAtOffset(uint32_t Off) const {
+  if (VBPtr && VBPtr->getOffsetInParent() == Off)
+    return true;
+  for (BaseClassLayout *BL : AllBases) {
+    if (BL->hasVBPtrAtOffset(Off - BL->getOffsetInParent()))
+      return true;
+  }
+  return false;
+}
+
+void UDTLayoutBase::addChildToLayout(std::unique_ptr<LayoutItemBase> Child) {
+  uint32_t Begin = Child->getOffsetInParent();
+
+  if (!Child->isElided()) {
+    BitVector ChildBytes = Child->usedBytes();
+
+    // Suppose the child occupies 4 bytes starting at offset 12 in a 32 byte
+    // class.  When we call ChildBytes.resize(32), the Child's storage will
+    // still begin at offset 0, so we need to shift it left by offset bytes
+    // to get it into the right position.
+    ChildBytes.resize(UsedBytes.size());
+    ChildBytes <<= Child->getOffsetInParent();
+    UsedBytes |= ChildBytes;
+
+    if (ChildBytes.count() > 0) {
+      auto Loc = std::upper_bound(LayoutItems.begin(), LayoutItems.end(), Begin,
+                                  [](uint32_t Off, const LayoutItemBase *Item) {
+                                    return (Off < Item->getOffsetInParent());
+                                  });
+
+      LayoutItems.insert(Loc, Child.get());
+    }
+  }
+
+  ChildStorage.push_back(std::move(Child));
+}