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llvm-project/lld/COFF/InputFiles.cpp

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//===- InputFiles.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 "InputFiles.h"
#include "Chunks.h"
#include "Config.h"
#include "DebugTypes.h"
#include "Driver.h"
#include "SymbolTable.h"
#include "Symbols.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/Memory.h"
#include "llvm-c/lto.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/COFF.h"
#include "llvm/DebugInfo/CodeView/DebugSubsectionRecord.h"
#include "llvm/DebugInfo/CodeView/SymbolDeserializer.h"
#include "llvm/DebugInfo/CodeView/SymbolRecord.h"
#include "llvm/DebugInfo/CodeView/TypeDeserializer.h"
#include "llvm/Object/Binary.h"
#include "llvm/Object/COFF.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
#include "llvm/Target/TargetOptions.h"
#include <cstring>
#include <system_error>
#include <utility>
using namespace llvm;
using namespace llvm::COFF;
using namespace llvm::codeview;
using namespace llvm::object;
using namespace llvm::support::endian;
using llvm::Triple;
using llvm::support::ulittle32_t;
namespace lld {
namespace coff {
std::vector<ObjFile *> ObjFile::Instances;
std::vector<ImportFile *> ImportFile::Instances;
std::vector<BitcodeFile *> BitcodeFile::Instances;
/// Checks that Source is compatible with being a weak alias to Target.
/// If Source is Undefined and has no weak alias set, makes it a weak
/// alias to Target.
static void checkAndSetWeakAlias(SymbolTable *Symtab, InputFile *F,
Symbol *Source, Symbol *Target) {
if (auto *U = dyn_cast<Undefined>(Source)) {
if (U->WeakAlias && U->WeakAlias != Target) {
// Weak aliases as produced by GCC are named in the form
// .weak.<weaksymbol>.<othersymbol>, where <othersymbol> is the name
// of another symbol emitted near the weak symbol.
// Just use the definition from the first object file that defined
// this weak symbol.
if (Config->MinGW)
return;
Symtab->reportDuplicate(Source, F);
}
U->WeakAlias = Target;
}
}
ArchiveFile::ArchiveFile(MemoryBufferRef M) : InputFile(ArchiveKind, M) {}
void ArchiveFile::parse() {
// Parse a MemoryBufferRef as an archive file.
File = CHECK(Archive::create(MB), this);
// Read the symbol table to construct Lazy objects.
for (const Archive::Symbol &Sym : File->symbols())
Symtab->addLazy(this, Sym);
}
// Returns a buffer pointing to a member file containing a given symbol.
void ArchiveFile::addMember(const Archive::Symbol *Sym) {
const Archive::Child &C =
CHECK(Sym->getMember(),
"could not get the member for symbol " + Sym->getName());
// Return an empty buffer if we have already returned the same buffer.
if (!Seen.insert(C.getChildOffset()).second)
return;
Driver->enqueueArchiveMember(C, Sym->getName(), getName());
}
std::vector<MemoryBufferRef> getArchiveMembers(Archive *File) {
std::vector<MemoryBufferRef> V;
Error Err = Error::success();
for (const ErrorOr<Archive::Child> &COrErr : File->children(Err)) {
Archive::Child C =
CHECK(COrErr,
File->getFileName() + ": could not get the child of the archive");
MemoryBufferRef MBRef =
CHECK(C.getMemoryBufferRef(),
File->getFileName() +
": could not get the buffer for a child of the archive");
V.push_back(MBRef);
}
if (Err)
fatal(File->getFileName() +
": Archive::children failed: " + toString(std::move(Err)));
return V;
}
void ObjFile::parse() {
// Parse a memory buffer as a COFF file.
std::unique_ptr<Binary> Bin = CHECK(createBinary(MB), this);
if (auto *Obj = dyn_cast<COFFObjectFile>(Bin.get())) {
Bin.release();
COFFObj.reset(Obj);
} else {
fatal(toString(this) + " is not a COFF file");
}
// Read section and symbol tables.
initializeChunks();
initializeSymbols();
initializeFlags();
initializeDependencies();
}
const coff_section* ObjFile::getSection(uint32_t I) {
const coff_section *Sec;
if (auto EC = COFFObj->getSection(I, Sec))
fatal("getSection failed: #" + Twine(I) + ": " + EC.message());
return Sec;
}
// We set SectionChunk pointers in the SparseChunks vector to this value
// temporarily to mark comdat sections as having an unknown resolution. As we
// walk the object file's symbol table, once we visit either a leader symbol or
// an associative section definition together with the parent comdat's leader,
// we set the pointer to either nullptr (to mark the section as discarded) or a
// valid SectionChunk for that section.
static SectionChunk *const PendingComdat = reinterpret_cast<SectionChunk *>(1);
void ObjFile::initializeChunks() {
uint32_t NumSections = COFFObj->getNumberOfSections();
Chunks.reserve(NumSections);
SparseChunks.resize(NumSections + 1);
for (uint32_t I = 1; I < NumSections + 1; ++I) {
const coff_section *Sec = getSection(I);
if (Sec->Characteristics & IMAGE_SCN_LNK_COMDAT)
SparseChunks[I] = PendingComdat;
else
SparseChunks[I] = readSection(I, nullptr, "");
}
}
SectionChunk *ObjFile::readSection(uint32_t SectionNumber,
const coff_aux_section_definition *Def,
StringRef LeaderName) {
const coff_section *Sec = getSection(SectionNumber);
StringRef Name;
if (Expected<StringRef> E = COFFObj->getSectionName(Sec))
Name = *E;
else
fatal("getSectionName failed: #" + Twine(SectionNumber) + ": " +
toString(E.takeError()));
if (Name == ".drectve") {
ArrayRef<uint8_t> Data;
cantFail(COFFObj->getSectionContents(Sec, Data));
Directives = StringRef((const char *)Data.data(), Data.size());
return nullptr;
}
if (Name == ".llvm_addrsig") {
AddrsigSec = Sec;
return nullptr;
}
// Object files may have DWARF debug info or MS CodeView debug info
// (or both).
//
// DWARF sections don't need any special handling from the perspective
// of the linker; they are just a data section containing relocations.
// We can just link them to complete debug info.
//
// CodeView needs linker support. We need to interpret debug info,
// and then write it to a separate .pdb file.
// Ignore DWARF debug info unless /debug is given.
if (!Config->Debug && Name.startswith(".debug_"))
return nullptr;
if (Sec->Characteristics & llvm::COFF::IMAGE_SCN_LNK_REMOVE)
return nullptr;
auto *C = make<SectionChunk>(this, Sec);
if (Def)
C->Checksum = Def->CheckSum;
// link.exe uses the presence of .rsrc$01 for LNK4078, so match that.
if (Name == ".rsrc$01")
IsResourceObjFile = true;
// CodeView sections are stored to a different vector because they are not
// linked in the regular manner.
if (C->isCodeView())
DebugChunks.push_back(C);
else if (Name == ".gfids$y")
GuardFidChunks.push_back(C);
else if (Name == ".gljmp$y")
GuardLJmpChunks.push_back(C);
else if (Name == ".sxdata")
SXDataChunks.push_back(C);
else if (Config->TailMerge && Sec->NumberOfRelocations == 0 &&
Name == ".rdata" && LeaderName.startswith("??_C@"))
// COFF sections that look like string literal sections (i.e. no
// relocations, in .rdata, leader symbol name matches the MSVC name mangling
// for string literals) are subject to string tail merging.
MergeChunk::addSection(C);
else
Chunks.push_back(C);
return C;
}
void ObjFile::readAssociativeDefinition(
COFFSymbolRef Sym, const coff_aux_section_definition *Def) {
readAssociativeDefinition(Sym, Def, Def->getNumber(Sym.isBigObj()));
}
void ObjFile::readAssociativeDefinition(COFFSymbolRef Sym,
const coff_aux_section_definition *Def,
uint32_t ParentIndex) {
SectionChunk *Parent = SparseChunks[ParentIndex];
int32_t SectionNumber = Sym.getSectionNumber();
auto Diag = [&]() {
StringRef Name, ParentName;
COFFObj->getSymbolName(Sym, Name);
const coff_section *ParentSec = getSection(ParentIndex);
if (Expected<StringRef> E = COFFObj->getSectionName(ParentSec))
ParentName = *E;
error(toString(this) + ": associative comdat " + Name + " (sec " +
Twine(SectionNumber) + ") has invalid reference to section " +
ParentName + " (sec " + Twine(ParentIndex) + ")");
};
if (Parent == PendingComdat) {
// This can happen if an associative comdat refers to another associative
// comdat that appears after it (invalid per COFF spec) or to a section
// without any symbols.
Diag();
return;
}
// Check whether the parent is prevailing. If it is, so are we, and we read
// the section; otherwise mark it as discarded.
if (Parent) {
SectionChunk *C = readSection(SectionNumber, Def, "");
SparseChunks[SectionNumber] = C;
if (C) {
C->Selection = IMAGE_COMDAT_SELECT_ASSOCIATIVE;
Parent->addAssociative(C);
}
} else {
SparseChunks[SectionNumber] = nullptr;
}
}
void ObjFile::recordPrevailingSymbolForMingw(
COFFSymbolRef Sym, DenseMap<StringRef, uint32_t> &PrevailingSectionMap) {
// For comdat symbols in executable sections, where this is the copy
// of the section chunk we actually include instead of discarding it,
// add the symbol to a map to allow using it for implicitly
// associating .[px]data$<func> sections to it.
int32_t SectionNumber = Sym.getSectionNumber();
SectionChunk *SC = SparseChunks[SectionNumber];
if (SC && SC->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE) {
StringRef Name;
COFFObj->getSymbolName(Sym, Name);
if (getMachineType() == I386)
Name.consume_front("_");
PrevailingSectionMap[Name] = SectionNumber;
}
}
void ObjFile::maybeAssociateSEHForMingw(
COFFSymbolRef Sym, const coff_aux_section_definition *Def,
const DenseMap<StringRef, uint32_t> &PrevailingSectionMap) {
StringRef Name;
COFFObj->getSymbolName(Sym, Name);
if (Name.consume_front(".pdata$") || Name.consume_front(".xdata$") ||
Name.consume_front(".eh_frame$")) {
// For MinGW, treat .[px]data$<func> and .eh_frame$<func> as implicitly
// associative to the symbol <func>.
auto ParentSym = PrevailingSectionMap.find(Name);
if (ParentSym != PrevailingSectionMap.end())
readAssociativeDefinition(Sym, Def, ParentSym->second);
}
}
Symbol *ObjFile::createRegular(COFFSymbolRef Sym) {
SectionChunk *SC = SparseChunks[Sym.getSectionNumber()];
if (Sym.isExternal()) {
StringRef Name;
COFFObj->getSymbolName(Sym, Name);
if (SC)
return Symtab->addRegular(this, Name, Sym.getGeneric(), SC);
// For MinGW symbols named .weak.* that point to a discarded section,
// don't create an Undefined symbol. If nothing ever refers to the symbol,
// everything should be fine. If something actually refers to the symbol
// (e.g. the undefined weak alias), linking will fail due to undefined
// references at the end.
if (Config->MinGW && Name.startswith(".weak."))
return nullptr;
return Symtab->addUndefined(Name, this, false);
}
if (SC)
return make<DefinedRegular>(this, /*Name*/ "", /*IsCOMDAT*/ false,
/*IsExternal*/ false, Sym.getGeneric(), SC);
return nullptr;
}
void ObjFile::initializeSymbols() {
uint32_t NumSymbols = COFFObj->getNumberOfSymbols();
Symbols.resize(NumSymbols);
SmallVector<std::pair<Symbol *, uint32_t>, 8> WeakAliases;
std::vector<uint32_t> PendingIndexes;
PendingIndexes.reserve(NumSymbols);
DenseMap<StringRef, uint32_t> PrevailingSectionMap;
std::vector<const coff_aux_section_definition *> ComdatDefs(
COFFObj->getNumberOfSections() + 1);
for (uint32_t I = 0; I < NumSymbols; ++I) {
COFFSymbolRef COFFSym = check(COFFObj->getSymbol(I));
bool PrevailingComdat;
if (COFFSym.isUndefined()) {
Symbols[I] = createUndefined(COFFSym);
} else if (COFFSym.isWeakExternal()) {
Symbols[I] = createUndefined(COFFSym);
uint32_t TagIndex = COFFSym.getAux<coff_aux_weak_external>()->TagIndex;
WeakAliases.emplace_back(Symbols[I], TagIndex);
} else if (Optional<Symbol *> OptSym =
createDefined(COFFSym, ComdatDefs, PrevailingComdat)) {
Symbols[I] = *OptSym;
if (Config->MinGW && PrevailingComdat)
recordPrevailingSymbolForMingw(COFFSym, PrevailingSectionMap);
} else {
// createDefined() returns None if a symbol belongs to a section that
// was pending at the point when the symbol was read. This can happen in
// two cases:
// 1) section definition symbol for a comdat leader;
// 2) symbol belongs to a comdat section associated with another section.
// In both of these cases, we can expect the section to be resolved by
// the time we finish visiting the remaining symbols in the symbol
// table. So we postpone the handling of this symbol until that time.
PendingIndexes.push_back(I);
}
I += COFFSym.getNumberOfAuxSymbols();
}
for (uint32_t I : PendingIndexes) {
COFFSymbolRef Sym = check(COFFObj->getSymbol(I));
if (const coff_aux_section_definition *Def = Sym.getSectionDefinition()) {
if (Def->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE)
readAssociativeDefinition(Sym, Def);
else if (Config->MinGW)
maybeAssociateSEHForMingw(Sym, Def, PrevailingSectionMap);
}
if (SparseChunks[Sym.getSectionNumber()] == PendingComdat) {
StringRef Name;
COFFObj->getSymbolName(Sym, Name);
log("comdat section " + Name +
" without leader and unassociated, discarding");
continue;
}
Symbols[I] = createRegular(Sym);
}
for (auto &KV : WeakAliases) {
Symbol *Sym = KV.first;
uint32_t Idx = KV.second;
checkAndSetWeakAlias(Symtab, this, Sym, Symbols[Idx]);
}
}
Symbol *ObjFile::createUndefined(COFFSymbolRef Sym) {
StringRef Name;
COFFObj->getSymbolName(Sym, Name);
return Symtab->addUndefined(Name, this, Sym.isWeakExternal());
}
void ObjFile::handleComdatSelection(COFFSymbolRef Sym, COMDATType &Selection,
bool &Prevailing, DefinedRegular *Leader) {
if (Prevailing)
return;
// There's already an existing comdat for this symbol: `Leader`.
// Use the comdats's selection field to determine if the new
// symbol in `Sym` should be discarded, produce a duplicate symbol
// error, etc.
SectionChunk *LeaderChunk = nullptr;
COMDATType LeaderSelection = IMAGE_COMDAT_SELECT_ANY;
if (Leader->Data) {
LeaderChunk = Leader->getChunk();
LeaderSelection = LeaderChunk->Selection;
} else {
// FIXME: comdats from LTO files don't know their selection; treat them
// as "any".
Selection = LeaderSelection;
}
if ((Selection == IMAGE_COMDAT_SELECT_ANY &&
LeaderSelection == IMAGE_COMDAT_SELECT_LARGEST) ||
(Selection == IMAGE_COMDAT_SELECT_LARGEST &&
LeaderSelection == IMAGE_COMDAT_SELECT_ANY)) {
// cl.exe picks "any" for vftables when building with /GR- and
// "largest" when building with /GR. To be able to link object files
// compiled with each flag, "any" and "largest" are merged as "largest".
LeaderSelection = Selection = IMAGE_COMDAT_SELECT_LARGEST;
}
// Other than that, comdat selections must match. This is a bit more
// strict than link.exe which allows merging "any" and "largest" if "any"
// is the first symbol the linker sees, and it allows merging "largest"
// with everything (!) if "largest" is the first symbol the linker sees.
// Making this symmetric independent of which selection is seen first
// seems better though.
// (This behavior matches ModuleLinker::getComdatResult().)
if (Selection != LeaderSelection) {
log(("conflicting comdat type for " + toString(*Leader) + ": " +
Twine((int)LeaderSelection) + " in " + toString(Leader->getFile()) +
" and " + Twine((int)Selection) + " in " + toString(this))
.str());
Symtab->reportDuplicate(Leader, this);
return;
}
switch (Selection) {
case IMAGE_COMDAT_SELECT_NODUPLICATES:
Symtab->reportDuplicate(Leader, this);
break;
case IMAGE_COMDAT_SELECT_ANY:
// Nothing to do.
break;
case IMAGE_COMDAT_SELECT_SAME_SIZE:
if (LeaderChunk->getSize() != getSection(Sym)->SizeOfRawData)
Symtab->reportDuplicate(Leader, this);
break;
case IMAGE_COMDAT_SELECT_EXACT_MATCH: {
SectionChunk NewChunk(this, getSection(Sym));
// link.exe only compares section contents here and doesn't complain
// if the two comdat sections have e.g. different alignment.
// Match that.
if (LeaderChunk->getContents() != NewChunk.getContents())
Symtab->reportDuplicate(Leader, this);
break;
}
case IMAGE_COMDAT_SELECT_ASSOCIATIVE:
// createDefined() is never called for IMAGE_COMDAT_SELECT_ASSOCIATIVE.
// (This means lld-link doesn't produce duplicate symbol errors for
// associative comdats while link.exe does, but associate comdats
// are never extern in practice.)
llvm_unreachable("createDefined not called for associative comdats");
case IMAGE_COMDAT_SELECT_LARGEST:
if (LeaderChunk->getSize() < getSection(Sym)->SizeOfRawData) {
// Replace the existing comdat symbol with the new one.
StringRef Name;
COFFObj->getSymbolName(Sym, Name);
// FIXME: This is incorrect: With /opt:noref, the previous sections
// make it into the final executable as well. Correct handling would
// be to undo reading of the whole old section that's being replaced,
// or doing one pass that determines what the final largest comdat
// is for all IMAGE_COMDAT_SELECT_LARGEST comdats and then reading
// only the largest one.
replaceSymbol<DefinedRegular>(Leader, this, Name, /*IsCOMDAT*/ true,
/*IsExternal*/ true, Sym.getGeneric(),
nullptr);
Prevailing = true;
}
break;
case IMAGE_COMDAT_SELECT_NEWEST:
llvm_unreachable("should have been rejected earlier");
}
}
Optional<Symbol *> ObjFile::createDefined(
COFFSymbolRef Sym,
std::vector<const coff_aux_section_definition *> &ComdatDefs,
bool &Prevailing) {
Prevailing = false;
auto GetName = [&]() {
StringRef S;
COFFObj->getSymbolName(Sym, S);
return S;
};
if (Sym.isCommon()) {
auto *C = make<CommonChunk>(Sym);
Chunks.push_back(C);
return Symtab->addCommon(this, GetName(), Sym.getValue(), Sym.getGeneric(),
C);
}
if (Sym.isAbsolute()) {
StringRef Name = GetName();
// Skip special symbols.
if (Name == "@comp.id")
return nullptr;
if (Name == "@feat.00") {
Feat00Flags = Sym.getValue();
return nullptr;
}
if (Sym.isExternal())
return Symtab->addAbsolute(Name, Sym);
return make<DefinedAbsolute>(Name, Sym);
}
int32_t SectionNumber = Sym.getSectionNumber();
if (SectionNumber == llvm::COFF::IMAGE_SYM_DEBUG)
return nullptr;
if (llvm::COFF::isReservedSectionNumber(SectionNumber))
fatal(toString(this) + ": " + GetName() +
" should not refer to special section " + Twine(SectionNumber));
if ((uint32_t)SectionNumber >= SparseChunks.size())
fatal(toString(this) + ": " + GetName() +
" should not refer to non-existent section " + Twine(SectionNumber));
// Comdat handling.
// A comdat symbol consists of two symbol table entries.
// The first symbol entry has the name of the section (e.g. .text), fixed
// values for the other fields, and one auxilliary record.
// The second symbol entry has the name of the comdat symbol, called the
// "comdat leader".
// When this function is called for the first symbol entry of a comdat,
// it sets ComdatDefs and returns None, and when it's called for the second
// symbol entry it reads ComdatDefs and then sets it back to nullptr.
// Handle comdat leader.
if (const coff_aux_section_definition *Def = ComdatDefs[SectionNumber]) {
ComdatDefs[SectionNumber] = nullptr;
DefinedRegular *Leader;
if (Sym.isExternal()) {
std::tie(Leader, Prevailing) =
Symtab->addComdat(this, GetName(), Sym.getGeneric());
} else {
Leader = make<DefinedRegular>(this, /*Name*/ "", /*IsCOMDAT*/ false,
/*IsExternal*/ false, Sym.getGeneric());
Prevailing = true;
}
if (Def->Selection < (int)IMAGE_COMDAT_SELECT_NODUPLICATES ||
// Intentionally ends at IMAGE_COMDAT_SELECT_LARGEST: link.exe
// doesn't understand IMAGE_COMDAT_SELECT_NEWEST either.
Def->Selection > (int)IMAGE_COMDAT_SELECT_LARGEST) {
fatal("unknown comdat type " + std::to_string((int)Def->Selection) +
" for " + GetName() + " in " + toString(this));
}
COMDATType Selection = (COMDATType)Def->Selection;
if (Leader->isCOMDAT())
handleComdatSelection(Sym, Selection, Prevailing, Leader);
if (Prevailing) {
SectionChunk *C = readSection(SectionNumber, Def, GetName());
SparseChunks[SectionNumber] = C;
C->Sym = cast<DefinedRegular>(Leader);
C->Selection = Selection;
cast<DefinedRegular>(Leader)->Data = &C->Repl;
} else {
SparseChunks[SectionNumber] = nullptr;
}
return Leader;
}
// Prepare to handle the comdat leader symbol by setting the section's
// ComdatDefs pointer if we encounter a non-associative comdat.
if (SparseChunks[SectionNumber] == PendingComdat) {
if (const coff_aux_section_definition *Def = Sym.getSectionDefinition()) {
if (Def->Selection != IMAGE_COMDAT_SELECT_ASSOCIATIVE)
ComdatDefs[SectionNumber] = Def;
}
return None;
}
return createRegular(Sym);
}
MachineTypes ObjFile::getMachineType() {
if (COFFObj)
return static_cast<MachineTypes>(COFFObj->getMachine());
return IMAGE_FILE_MACHINE_UNKNOWN;
}
ArrayRef<uint8_t> ObjFile::getDebugSection(StringRef SecName) {
if (SectionChunk *Sec = SectionChunk::findByName(DebugChunks, SecName))
return Sec->consumeDebugMagic();
return {};
}
// OBJ files systematically store critical informations in a .debug$S stream,
// even if the TU was compiled with no debug info. At least two records are
// always there. S_OBJNAME stores a 32-bit signature, which is loaded into the
// PCHSignature member. S_COMPILE3 stores compile-time cmd-line flags. This is
// currently used to initialize the HotPatchable member.
void ObjFile::initializeFlags() {
ArrayRef<uint8_t> Data = getDebugSection(".debug$S");
if (Data.empty())
return;
DebugSubsectionArray Subsections;
BinaryStreamReader Reader(Data, support::little);
ExitOnError ExitOnErr;
ExitOnErr(Reader.readArray(Subsections, Data.size()));
for (const DebugSubsectionRecord &SS : Subsections) {
if (SS.kind() != DebugSubsectionKind::Symbols)
continue;
unsigned Offset = 0;
// Only parse the first two records. We are only looking for S_OBJNAME
// and S_COMPILE3, and they usually appear at the beginning of the
// stream.
for (unsigned I = 0; I < 2; ++I) {
Expected<CVSymbol> Sym = readSymbolFromStream(SS.getRecordData(), Offset);
if (!Sym) {
consumeError(Sym.takeError());
return;
}
if (Sym->kind() == SymbolKind::S_COMPILE3) {
auto CS =
cantFail(SymbolDeserializer::deserializeAs<Compile3Sym>(Sym.get()));
HotPatchable =
(CS.Flags & CompileSym3Flags::HotPatch) != CompileSym3Flags::None;
}
if (Sym->kind() == SymbolKind::S_OBJNAME) {
auto ObjName = cantFail(SymbolDeserializer::deserializeAs<ObjNameSym>(
Sym.get()));
PCHSignature = ObjName.Signature;
}
Offset += Sym->length();
}
}
}
// Depending on the compilation flags, OBJs can refer to external files,
// necessary to merge this OBJ into the final PDB. We currently support two
// types of external files: Precomp/PCH OBJs, when compiling with /Yc and /Yu.
// And PDB type servers, when compiling with /Zi. This function extracts these
// dependencies and makes them available as a TpiSource interface (see
// DebugTypes.h). Both cases only happen with cl.exe: clang-cl produces regular
// output even with /Yc and /Yu and with /Zi.
void ObjFile::initializeDependencies() {
if (!Config->Debug)
return;
bool IsPCH = false;
ArrayRef<uint8_t> Data = getDebugSection(".debug$P");
if (!Data.empty())
IsPCH = true;
else
Data = getDebugSection(".debug$T");
if (Data.empty())
return;
CVTypeArray Types;
BinaryStreamReader Reader(Data, support::little);
cantFail(Reader.readArray(Types, Reader.getLength()));
CVTypeArray::Iterator FirstType = Types.begin();
if (FirstType == Types.end())
return;
DebugTypes.emplace(Types);
if (IsPCH) {
DebugTypesObj = makePrecompSource(this);
return;
}
if (FirstType->kind() == LF_TYPESERVER2) {
TypeServer2Record TS = cantFail(
TypeDeserializer::deserializeAs<TypeServer2Record>(FirstType->data()));
DebugTypesObj = makeUseTypeServerSource(this, &TS);
return;
}
if (FirstType->kind() == LF_PRECOMP) {
PrecompRecord Precomp = cantFail(
TypeDeserializer::deserializeAs<PrecompRecord>(FirstType->data()));
DebugTypesObj = makeUsePrecompSource(this, &Precomp);
return;
}
DebugTypesObj = makeTpiSource(this);
}
StringRef ltrim1(StringRef S, const char *Chars) {
if (!S.empty() && strchr(Chars, S[0]))
return S.substr(1);
return S;
}
void ImportFile::parse() {
const char *Buf = MB.getBufferStart();
const auto *Hdr = reinterpret_cast<const coff_import_header *>(Buf);
// Check if the total size is valid.
if (MB.getBufferSize() != sizeof(*Hdr) + Hdr->SizeOfData)
fatal("broken import library");
// Read names and create an __imp_ symbol.
StringRef Name = Saver.save(StringRef(Buf + sizeof(*Hdr)));
StringRef ImpName = Saver.save("__imp_" + Name);
const char *NameStart = Buf + sizeof(coff_import_header) + Name.size() + 1;
DLLName = StringRef(NameStart);
StringRef ExtName;
switch (Hdr->getNameType()) {
case IMPORT_ORDINAL:
ExtName = "";
break;
case IMPORT_NAME:
ExtName = Name;
break;
case IMPORT_NAME_NOPREFIX:
ExtName = ltrim1(Name, "?@_");
break;
case IMPORT_NAME_UNDECORATE:
ExtName = ltrim1(Name, "?@_");
ExtName = ExtName.substr(0, ExtName.find('@'));
break;
}
this->Hdr = Hdr;
ExternalName = ExtName;
ImpSym = Symtab->addImportData(ImpName, this);
// If this was a duplicate, we logged an error but may continue;
// in this case, ImpSym is nullptr.
if (!ImpSym)
return;
if (Hdr->getType() == llvm::COFF::IMPORT_CONST)
static_cast<void>(Symtab->addImportData(Name, this));
// If type is function, we need to create a thunk which jump to an
// address pointed by the __imp_ symbol. (This allows you to call
// DLL functions just like regular non-DLL functions.)
if (Hdr->getType() == llvm::COFF::IMPORT_CODE)
ThunkSym = Symtab->addImportThunk(
Name, cast_or_null<DefinedImportData>(ImpSym), Hdr->Machine);
}
BitcodeFile::BitcodeFile(MemoryBufferRef MB, StringRef ArchiveName,
uint64_t OffsetInArchive)
: InputFile(BitcodeKind, MB) {
std::string Path = MB.getBufferIdentifier().str();
// ThinLTO assumes that all MemoryBufferRefs given to it have a unique
// name. If two archives define two members with the same name, this
// causes a collision which result in only one of the objects being taken
// into consideration at LTO time (which very likely causes undefined
// symbols later in the link stage). So we append file offset to make
// filename unique.
MemoryBufferRef MBRef(
MB.getBuffer(),
Saver.save(ArchiveName + Path +
(ArchiveName.empty() ? "" : utostr(OffsetInArchive))));
Obj = check(lto::InputFile::create(MBRef));
}
void BitcodeFile::parse() {
std::vector<std::pair<Symbol *, bool>> Comdat(Obj->getComdatTable().size());
for (size_t I = 0; I != Obj->getComdatTable().size(); ++I)
// FIXME: lto::InputFile doesn't keep enough data to do correct comdat
// selection handling.
Comdat[I] = Symtab->addComdat(this, Saver.save(Obj->getComdatTable()[I]));
for (const lto::InputFile::Symbol &ObjSym : Obj->symbols()) {
StringRef SymName = Saver.save(ObjSym.getName());
int ComdatIndex = ObjSym.getComdatIndex();
Symbol *Sym;
if (ObjSym.isUndefined()) {
Sym = Symtab->addUndefined(SymName, this, false);
} else if (ObjSym.isCommon()) {
Sym = Symtab->addCommon(this, SymName, ObjSym.getCommonSize());
} else if (ObjSym.isWeak() && ObjSym.isIndirect()) {
// Weak external.
Sym = Symtab->addUndefined(SymName, this, true);
std::string Fallback = ObjSym.getCOFFWeakExternalFallback();
Symbol *Alias = Symtab->addUndefined(Saver.save(Fallback));
checkAndSetWeakAlias(Symtab, this, Sym, Alias);
} else if (ComdatIndex != -1) {
if (SymName == Obj->getComdatTable()[ComdatIndex])
Sym = Comdat[ComdatIndex].first;
else if (Comdat[ComdatIndex].second)
Sym = Symtab->addRegular(this, SymName);
else
Sym = Symtab->addUndefined(SymName, this, false);
} else {
Sym = Symtab->addRegular(this, SymName);
}
Symbols.push_back(Sym);
if (ObjSym.isUsed())
Config->GCRoot.push_back(Sym);
}
Directives = Obj->getCOFFLinkerOpts();
}
MachineTypes BitcodeFile::getMachineType() {
switch (Triple(Obj->getTargetTriple()).getArch()) {
case Triple::x86_64:
return AMD64;
case Triple::x86:
return I386;
case Triple::arm:
return ARMNT;
case Triple::aarch64:
return ARM64;
default:
return IMAGE_FILE_MACHINE_UNKNOWN;
}
}
} // namespace coff
} // namespace lld
// Returns the last element of a path, which is supposed to be a filename.
static StringRef getBasename(StringRef Path) {
return sys::path::filename(Path, sys::path::Style::windows);
}
// Returns a string in the format of "foo.obj" or "foo.obj(bar.lib)".
std::string lld::toString(const coff::InputFile *File) {
if (!File)
return "<internal>";
if (File->ParentName.empty() || File->kind() == coff::InputFile::ImportKind)
return File->getName();
return (getBasename(File->ParentName) + "(" + getBasename(File->getName()) +
")")
.str();
}
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