Optional<coff_symbol16> Writer::createSymbol(Defined *Def) {
// Relative symbols are unrepresentable in a COFF symbol table.
if (isa<DefinedSynthetic>(Def))
return None;
if (auto *D = dyn_cast<DefinedRegular>(Def)) {
// Don't write dead symbols or symbols in codeview sections to the symbol
// table.
if (!D->getChunk()->isLive() || D->getChunk()->isCodeView())
return None;
}
if (auto *Sym = dyn_cast<DefinedImportData>(Def))
if (!Sym->File->Live)
return None;
if (auto *Sym = dyn_cast<DefinedImportThunk>(Def))
if (!Sym->WrappedSym->File->Live)
return None;
coff_symbol16 Sym;
StringRef Name = Def->getName();
if (Name.size() > COFF::NameSize) {
Sym.Name.Offset.Zeroes = 0;
Sym.Name.Offset.Offset = addEntryToStringTable(Name);
} else {
memset(Sym.Name.ShortName, 0, COFF::NameSize);
memcpy(Sym.Name.ShortName, Name.data(), Name.size());
}
if (auto *D = dyn_cast<DefinedCOFF>(Def)) {
COFFSymbolRef Ref = D->getCOFFSymbol();
Sym.Type = Ref.getType();
Sym.StorageClass = Ref.getStorageClass();
} else {
Sym.Type = IMAGE_SYM_TYPE_NULL;
Sym.StorageClass = IMAGE_SYM_CLASS_EXTERNAL;
}
Sym.NumberOfAuxSymbols = 0;
switch (Def->kind()) {
case SymbolBody::DefinedAbsoluteKind:
Sym.Value = Def->getRVA();
Sym.SectionNumber = IMAGE_SYM_ABSOLUTE;
break;
default: {
uint64_t RVA = Def->getRVA();
OutputSection *Sec = nullptr;
for (OutputSection *S : OutputSections) {
if (S->getRVA() > RVA)
break;
Sec = S;
}
Sym.Value = RVA - Sec->getRVA();
Sym.SectionNumber = Sec->SectionIndex;
break;
}
}
return Sym;
}
void Writer::createExportTable() {
if (Config->Exports.empty())
return;
OutputSection *Sec = createSection(".edata");
for (std::unique_ptr<Chunk> &C : Edata.Chunks)
Sec->addChunk(C.get());
}
// Create relocations sections in the final output.
// These are only created when relocatable output is requested.
void Writer::createRelocSections() {
log("createRelocSections");
// Don't use iterator here since we are adding to OutputSection
size_t OrigSize = OutputSections.size();
for (size_t I = 0; I < OrigSize; I++) {
OutputSection *OSec = OutputSections[I];
uint32_t Count = OSec->numRelocations();
if (!Count)
continue;
StringRef Name;
if (OSec->Type == WASM_SEC_DATA)
Name = "reloc.DATA";
else if (OSec->Type == WASM_SEC_CODE)
Name = "reloc.CODE";
else if (OSec->Type == WASM_SEC_CUSTOM)
Name = Saver.save("reloc." + OSec->Name);
else
llvm_unreachable(
"relocations only supported for code, data, or custom sections");
SyntheticSection *Section = createSyntheticSection(WASM_SEC_CUSTOM, Name);
raw_ostream &OS = Section->getStream();
writeUleb128(OS, I, "reloc section");
writeUleb128(OS, Count, "reloc count");
OSec->writeRelocations(OS);
}
}
void Writer::createExportTable() {
if (Config->Exports.empty())
return;
OutputSection *Sec = createSection(".edata");
for (Chunk *C : Edata.Chunks)
Sec->addChunk(C);
}
void Writer::createMiscChunks() {
OutputSection *RData = createSection(".rdata");
// Create thunks for locally-dllimported symbols.
if (!Symtab->LocalImportChunks.empty()) {
for (Chunk *C : Symtab->LocalImportChunks)
RData->addChunk(C);
}
// Create Debug Information Chunks
if (Config->Debug) {
DebugDirectory = make<DebugDirectoryChunk>(DebugRecords);
// TODO(compnerd) create a coffgrp entry if DebugType::CV is not enabled
if (Config->DebugTypes & static_cast<unsigned>(coff::DebugType::CV)) {
auto *Chunk = make<CVDebugRecordChunk>();
BuildId = Chunk;
DebugRecords.push_back(Chunk);
}
RData->addChunk(DebugDirectory);
for (Chunk *C : DebugRecords)
RData->addChunk(C);
}
// Create SEH table. x86-only.
if (Config->Machine != I386)
return;
std::set<Defined *> Handlers;
for (lld::coff::ObjectFile *File : Symtab->ObjectFiles) {
if (!File->SEHCompat)
return;
for (SymbolBody *B : File->SEHandlers) {
// Make sure the handler is still live. Assume all handlers are regular
// symbols.
auto *D = dyn_cast<DefinedRegular>(B);
if (D && D->getChunk()->isLive())
Handlers.insert(D);
}
}
if (!Handlers.empty()) {
SEHTable = make<SEHTableChunk>(Handlers);
RData->addChunk(SEHTable);
}
}
Optional<coff_symbol16> Writer::createSymbol(Defined *Def) {
if (auto *D = dyn_cast<DefinedRegular>(Def))
if (!D->getChunk()->isLive())
return None;
coff_symbol16 Sym;
StringRef Name = Def->getName();
if (Name.size() > COFF::NameSize) {
Sym.Name.Offset.Zeroes = 0;
Sym.Name.Offset.Offset = addEntryToStringTable(Name);
} else {
memset(Sym.Name.ShortName, 0, COFF::NameSize);
memcpy(Sym.Name.ShortName, Name.data(), Name.size());
}
if (auto *D = dyn_cast<DefinedCOFF>(Def)) {
COFFSymbolRef Ref = D->getCOFFSymbol();
Sym.Type = Ref.getType();
Sym.StorageClass = Ref.getStorageClass();
} else {
Sym.Type = IMAGE_SYM_TYPE_NULL;
Sym.StorageClass = IMAGE_SYM_CLASS_EXTERNAL;
}
Sym.NumberOfAuxSymbols = 0;
switch (Def->kind()) {
case SymbolBody::DefinedAbsoluteKind:
case SymbolBody::DefinedRelativeKind:
Sym.Value = Def->getRVA();
Sym.SectionNumber = IMAGE_SYM_ABSOLUTE;
break;
default: {
uint64_t RVA = Def->getRVA();
OutputSection *Sec = nullptr;
for (OutputSection *S : OutputSections) {
if (S->getRVA() > RVA)
break;
Sec = S;
}
Sym.Value = RVA - Sec->getRVA();
Sym.SectionNumber = Sec->SectionIndex;
break;
}
}
return Sym;
}
// Create .idata section for the DLL-imported symbol table.
// The format of this section is inherently Windows-specific.
// IdataContents class abstracted away the details for us,
// so we just let it create chunks and add them to the section.
void Writer::createImportTables() {
if (Symtab->ImportFiles.empty())
return;
// Initialize DLLOrder so that import entries are ordered in
// the same order as in the command line. (That affects DLL
// initialization order, and this ordering is MSVC-compatible.)
for (ImportFile *File : Symtab->ImportFiles) {
if (!File->Live)
continue;
std::string DLL = StringRef(File->DLLName).lower();
if (Config->DLLOrder.count(DLL) == 0)
Config->DLLOrder[DLL] = Config->DLLOrder.size();
}
OutputSection *Text = createSection(".text");
for (ImportFile *File : Symtab->ImportFiles) {
if (!File->Live)
continue;
if (DefinedImportThunk *Thunk = File->ThunkSym)
Text->addChunk(Thunk->getChunk());
if (Config->DelayLoads.count(StringRef(File->DLLName).lower())) {
if (!File->ThunkSym)
fatal("cannot delay-load " + toString(File) +
" due to import of data: " + toString(*File->ImpSym));
DelayIdata.add(File->ImpSym);
} else {
Idata.add(File->ImpSym);
}
}
if (!Idata.empty()) {
OutputSection *Sec = createSection(".idata");
for (Chunk *C : Idata.getChunks())
Sec->addChunk(C);
}
if (!DelayIdata.empty()) {
Defined *Helper = cast<Defined>(Config->DelayLoadHelper);
DelayIdata.create(Helper);
OutputSection *Sec = createSection(".didat");
for (Chunk *C : DelayIdata.getChunks())
Sec->addChunk(C);
Sec = createSection(".data");
for (Chunk *C : DelayIdata.getDataChunks())
Sec->addChunk(C);
Sec = createSection(".text");
for (Chunk *C : DelayIdata.getCodeChunks())
Sec->addChunk(C);
}
}
void Writer::createMiscChunks() {
// Create thunks for locally-dllimported symbols.
if (!Symtab->LocalImportChunks.empty()) {
OutputSection *Sec = createSection(".rdata");
for (Chunk *C : Symtab->LocalImportChunks)
Sec->addChunk(C);
}
// Create SEH table. x86-only.
if (Config->Machine != I386)
return;
std::set<Defined *> Handlers;
for (lld::coff::ObjectFile *File : Symtab->ObjectFiles) {
if (!File->SEHCompat)
return;
for (SymbolBody *B : File->SEHandlers)
Handlers.insert(cast<Defined>(B->repl()));
}
SEHTable.reset(new SEHTableChunk(Handlers));
createSection(".rdata")->addChunk(SEHTable.get());
}
// Sort .pdata section contents according to PE/COFF spec 5.5.
void Writer::sortExceptionTable() {
OutputSection *Sec = findSection(".pdata");
if (!Sec)
return;
// We assume .pdata contains function table entries only.
uint8_t *Begin = Buffer->getBufferStart() + Sec->getFileOff();
uint8_t *End = Begin + Sec->getVirtualSize();
if (Config->Machine == AMD64) {
struct Entry { ulittle32_t Begin, End, Unwind; };
sort(parallel::par, (Entry *)Begin, (Entry *)End,
[](const Entry &A, const Entry &B) { return A.Begin < B.Begin; });
return;
}
if (Config->Machine == ARMNT) {
struct Entry { ulittle32_t Begin, Unwind; };
sort(parallel::par, (Entry *)Begin, (Entry *)End,
[](const Entry &A, const Entry &B) { return A.Begin < B.Begin; });
return;
}
errs() << "warning: don't know how to handle .pdata.\n";
}
void Writer::createSymbolAndStringTable() {
if (!Config->Debug || !Config->WriteSymtab)
return;
// Name field in the section table is 8 byte long. Longer names need
// to be written to the string table. First, construct string table.
for (OutputSection *Sec : OutputSections) {
StringRef Name = Sec->getName();
if (Name.size() <= COFF::NameSize)
continue;
Sec->setStringTableOff(addEntryToStringTable(Name));
}
for (lld::coff::ObjectFile *File : Symtab->ObjectFiles) {
for (SymbolBody *B : File->getSymbols()) {
auto *D = dyn_cast<Defined>(B);
if (!D || D->WrittenToSymtab)
continue;
D->WrittenToSymtab = true;
if (Optional<coff_symbol16> Sym = createSymbol(D))
OutputSymtab.push_back(*Sym);
}
}
OutputSection *LastSection = OutputSections.back();
// We position the symbol table to be adjacent to the end of the last section.
uint64_t FileOff = LastSection->getFileOff() +
alignTo(LastSection->getRawSize(), SectorSize);
if (!OutputSymtab.empty()) {
PointerToSymbolTable = FileOff;
FileOff += OutputSymtab.size() * sizeof(coff_symbol16);
}
if (!Strtab.empty())
FileOff += Strtab.size() + 4;
FileSize = alignTo(FileOff, SectorSize);
}
static OutputSection *createSection(InputSectionBase *IS,
StringRef OutsecName) {
OutputSection *Sec = Script->createOutputSection(OutsecName, "<internal>");
Sec->addSection(cast<InputSection>(IS));
return Sec;
}
