llvm-mirror/lib/DebugInfo/PDB/UDTLayout.cpp
Simon Pilgrim cb12c82cda [DebugInfo] Don't dereference a dyn_cast<PDBSymbolData> result. NFCI.
The static analyzer is warning about a potential null dereference - but as we're in DataMemberLayoutItem we should be able to guarantee that the Symbol is a PDBSymbolData type, allowing us to use cast<PDBSymbolData> - and if not assert will fire for us.

llvm-svn: 371933
2019-09-15 15:38:26 +00:00

303 lines
11 KiB
C++

//===- 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));
}