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LinkerScript.cpp
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LinkerScript.cpp
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//===- LinkerScript.cpp ---------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the parser/evaluator of the linker script.
// It parses a linker script and write the result to Config or ScriptConfig
// objects.
//
// If SECTIONS command is used, a ScriptConfig contains an AST
// of the command which will later be consumed by createSections() and
// assignAddresses().
//
//===----------------------------------------------------------------------===//
#include "LinkerScript.h"
#include "Config.h"
#include "Driver.h"
#include "InputSection.h"
#include "OutputSections.h"
#include "ScriptParser.h"
#include "Strings.h"
#include "Symbols.h"
#include "SymbolTable.h"
#include "Target.h"
#include "Writer.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/StringSaver.h"
using namespace llvm;
using namespace llvm::ELF;
using namespace llvm::object;
using namespace lld;
using namespace lld::elf;
ScriptConfiguration *elf::ScriptConfig;
template <class ELFT>
static void addRegular(SymbolAssignment *Cmd) {
Symbol *Sym = Symtab<ELFT>::X->addRegular(Cmd->Name, STB_GLOBAL, STV_DEFAULT);
Sym->Visibility = Cmd->Hidden ? STV_HIDDEN : STV_DEFAULT;
Cmd->Sym = Sym->body();
}
template <class ELFT> static void addSynthetic(SymbolAssignment *Cmd) {
Symbol *Sym = Symtab<ELFT>::X->addSynthetic(
Cmd->Name, nullptr, 0, Cmd->Hidden ? STV_HIDDEN : STV_DEFAULT);
Cmd->Sym = Sym->body();
}
// If a symbol was in PROVIDE(), we need to define it only when
// it is an undefined symbol.
template <class ELFT> static bool shouldDefine(SymbolAssignment *Cmd) {
if (Cmd->Name == ".")
return false;
if (!Cmd->Provide)
return true;
SymbolBody *B = Symtab<ELFT>::X->find(Cmd->Name);
return B && B->isUndefined();
}
bool SymbolAssignment::classof(const BaseCommand *C) {
return C->Kind == AssignmentKind;
}
bool OutputSectionCommand::classof(const BaseCommand *C) {
return C->Kind == OutputSectionKind;
}
bool InputSectionDescription::classof(const BaseCommand *C) {
return C->Kind == InputSectionKind;
}
bool AssertCommand::classof(const BaseCommand *C) {
return C->Kind == AssertKind;
}
template <class ELFT> static bool isDiscarded(InputSectionBase<ELFT> *S) {
return !S || !S->Live;
}
template <class ELFT> LinkerScript<ELFT>::LinkerScript() {}
template <class ELFT> LinkerScript<ELFT>::~LinkerScript() {}
template <class ELFT>
bool LinkerScript<ELFT>::shouldKeep(InputSectionBase<ELFT> *S) {
for (StringRef Pat : Opt.KeptSections)
if (globMatch(Pat, S->getSectionName()))
return true;
return false;
}
static bool match(ArrayRef<StringRef> Patterns, StringRef S) {
for (StringRef Pat : Patterns)
if (globMatch(Pat, S))
return true;
return false;
}
static bool fileMatches(const InputSectionDescription *Desc,
StringRef Filename) {
if (!globMatch(Desc->FilePattern, Filename))
return false;
return Desc->ExcludedFiles.empty() || !match(Desc->ExcludedFiles, Filename);
}
// Returns input sections filtered by given glob patterns.
template <class ELFT>
std::vector<InputSectionBase<ELFT> *>
LinkerScript<ELFT>::getInputSections(const InputSectionDescription *I) {
ArrayRef<StringRef> Patterns = I->SectionPatterns;
std::vector<InputSectionBase<ELFT> *> Ret;
for (const std::unique_ptr<ObjectFile<ELFT>> &F :
Symtab<ELFT>::X->getObjectFiles()) {
if (fileMatches(I, sys::path::filename(F->getName())))
for (InputSectionBase<ELFT> *S : F->getSections())
if (!isDiscarded(S) && !S->OutSec &&
match(Patterns, S->getSectionName()))
Ret.push_back(S);
}
if (llvm::find(Patterns, "COMMON") != Patterns.end())
Ret.push_back(CommonInputSection<ELFT>::X);
return Ret;
}
// You can define new symbols using linker scripts. For example,
// ".text { abc.o(.text); foo = .; def.o(.text); }" defines symbol
// foo just after abc.o's text section contents. This class is to
// handle such symbol definitions.
//
// In order to handle scripts like the above one, we want to
// keep symbol definitions in output sections. Because output sections
// can contain only input sections, we wrap symbol definitions
// with dummy input sections. This class serves that purpose.
template <class ELFT>
class elf::LayoutInputSection : public InputSectionBase<ELFT> {
public:
explicit LayoutInputSection(SymbolAssignment *Cmd);
static bool classof(const InputSectionBase<ELFT> *S);
SymbolAssignment *Cmd;
private:
typename ELFT::Shdr Hdr;
};
template <class ELFT>
static InputSectionBase<ELFT> *
getNonLayoutSection(std::vector<InputSectionBase<ELFT> *> &Vec) {
for (InputSectionBase<ELFT> *S : Vec)
if (!isa<LayoutInputSection<ELFT>>(S))
return S;
return nullptr;
}
template <class T> static T *zero(T *Val) {
memset(Val, 0, sizeof(*Val));
return Val;
}
template <class ELFT>
LayoutInputSection<ELFT>::LayoutInputSection(SymbolAssignment *Cmd)
: InputSectionBase<ELFT>(nullptr, zero(&Hdr),
InputSectionBase<ELFT>::Layout),
Cmd(Cmd) {
this->Live = true;
Hdr.sh_type = SHT_NOBITS;
}
template <class ELFT>
bool LayoutInputSection<ELFT>::classof(const InputSectionBase<ELFT> *S) {
return S->SectionKind == InputSectionBase<ELFT>::Layout;
}
template <class ELFT>
static bool compareName(InputSectionBase<ELFT> *A, InputSectionBase<ELFT> *B) {
return A->getSectionName() < B->getSectionName();
}
template <class ELFT>
static bool compareAlignment(InputSectionBase<ELFT> *A,
InputSectionBase<ELFT> *B) {
// ">" is not a mistake. Larger alignments are placed before smaller
// alignments in order to reduce the amount of padding necessary.
// This is compatible with GNU.
return A->Alignment > B->Alignment;
}
template <class ELFT>
static std::function<bool(InputSectionBase<ELFT> *, InputSectionBase<ELFT> *)>
getComparator(SortKind K) {
if (K == SortByName)
return compareName<ELFT>;
return compareAlignment<ELFT>;
}
template <class ELFT>
void LinkerScript<ELFT>::discard(OutputSectionCommand &Cmd) {
for (const std::unique_ptr<BaseCommand> &Base : Cmd.Commands) {
if (auto *Cmd = dyn_cast<InputSectionDescription>(Base.get())) {
for (InputSectionBase<ELFT> *S : getInputSections(Cmd)) {
S->Live = false;
reportDiscarded(S);
}
}
}
}
static bool checkConstraint(uint64_t Flags, ConstraintKind Kind) {
bool RO = (Kind == ConstraintKind::ReadOnly);
bool RW = (Kind == ConstraintKind::ReadWrite);
bool Writable = Flags & SHF_WRITE;
return !((RO && Writable) || (RW && !Writable));
}
template <class ELFT>
static bool matchConstraints(ArrayRef<InputSectionBase<ELFT> *> Sections,
ConstraintKind Kind) {
if (Kind == ConstraintKind::NoConstraint)
return true;
return llvm::all_of(Sections, [=](InputSectionBase<ELFT> *Sec) {
return checkConstraint(Sec->getSectionHdr()->sh_flags, Kind);
});
}
template <class ELFT>
std::vector<InputSectionBase<ELFT> *>
LinkerScript<ELFT>::createInputSectionList(OutputSectionCommand &OutCmd) {
std::vector<InputSectionBase<ELFT> *> Ret;
for (const std::unique_ptr<BaseCommand> &Base : OutCmd.Commands) {
if (auto *OutCmd = dyn_cast<SymbolAssignment>(Base.get())) {
if (shouldDefine<ELFT>(OutCmd))
addSynthetic<ELFT>(OutCmd);
Ret.push_back(new (LAlloc.Allocate()) LayoutInputSection<ELFT>(OutCmd));
continue;
}
auto *Cmd = cast<InputSectionDescription>(Base.get());
std::vector<InputSectionBase<ELFT> *> V = getInputSections(Cmd);
if (!matchConstraints<ELFT>(V, OutCmd.Constraint))
continue;
if (Cmd->SortInner)
std::stable_sort(V.begin(), V.end(), getComparator<ELFT>(Cmd->SortInner));
if (Cmd->SortOuter)
std::stable_sort(V.begin(), V.end(), getComparator<ELFT>(Cmd->SortOuter));
Ret.insert(Ret.end(), V.begin(), V.end());
}
return Ret;
}
template <class ELFT>
void LinkerScript<ELFT>::createSections(OutputSectionFactory<ELFT> &Factory) {
for (const std::unique_ptr<BaseCommand> &Base1 : Opt.Commands) {
if (auto *Cmd = dyn_cast<SymbolAssignment>(Base1.get())) {
if (shouldDefine<ELFT>(Cmd))
addRegular<ELFT>(Cmd);
continue;
}
if (auto *Cmd = dyn_cast<OutputSectionCommand>(Base1.get())) {
if (Cmd->Name == "/DISCARD/") {
discard(*Cmd);
continue;
}
std::vector<InputSectionBase<ELFT> *> V = createInputSectionList(*Cmd);
InputSectionBase<ELFT> *Head = getNonLayoutSection<ELFT>(V);
if (!Head)
continue;
OutputSectionBase<ELFT> *OutSec;
bool IsNew;
std::tie(OutSec, IsNew) = Factory.create(Head, Cmd->Name);
if (IsNew)
OutputSections->push_back(OutSec);
uint32_t Subalign = Cmd->SubalignExpr ? Cmd->SubalignExpr(0) : 0;
for (InputSectionBase<ELFT> *Sec : V) {
if (Subalign)
Sec->Alignment = Subalign;
if (!Sec->OutSec)
OutSec->addSection(Sec);
}
}
}
// Add orphan sections.
for (const std::unique_ptr<ObjectFile<ELFT>> &F :
Symtab<ELFT>::X->getObjectFiles()) {
for (InputSectionBase<ELFT> *S : F->getSections()) {
if (isDiscarded(S) || S->OutSec)
continue;
OutputSectionBase<ELFT> *OutSec;
bool IsNew;
std::tie(OutSec, IsNew) = Factory.create(S, getOutputSectionName(S));
if (IsNew)
OutputSections->push_back(OutSec);
OutSec->addSection(S);
}
}
}
template <class ELFT> void assignOffsets(OutputSectionBase<ELFT> *Sec) {
auto *OutSec = dyn_cast<OutputSection<ELFT>>(Sec);
if (!OutSec) {
Sec->assignOffsets();
return;
}
typedef typename ELFT::uint uintX_t;
uintX_t Off = 0;
for (InputSection<ELFT> *I : OutSec->Sections) {
if (auto *L = dyn_cast<LayoutInputSection<ELFT>>(I)) {
uintX_t Value = L->Cmd->Expression(Sec->getVA() + Off) - Sec->getVA();
if (L->Cmd->Name == ".") {
Off = Value;
} else if (auto *Sym =
cast_or_null<DefinedSynthetic<ELFT>>(L->Cmd->Sym)) {
// shouldDefine could have returned false, so we need to check Sym,
// for non-null value.
Sym->Section = OutSec;
Sym->Value = Value;
}
} else {
Off = alignTo(Off, I->Alignment);
I->OutSecOff = Off;
Off += I->getSize();
}
// Update section size inside for-loop, so that SIZEOF
// works correctly in the case below:
// .foo { *(.aaa) a = SIZEOF(.foo); *(.bbb) }
Sec->setSize(Off);
}
}
template <class ELFT>
static OutputSectionBase<ELFT> *
findSection(OutputSectionCommand &Cmd,
ArrayRef<OutputSectionBase<ELFT> *> Sections) {
for (OutputSectionBase<ELFT> *Sec : Sections) {
if (Sec->getName() != Cmd.Name)
continue;
if (checkConstraint(Sec->getFlags(), Cmd.Constraint))
return Sec;
}
return nullptr;
}
template <class ELFT> void LinkerScript<ELFT>::assignAddresses() {
// Orphan sections are sections present in the input files which
// are not explicitly placed into the output file by the linker script.
// We place orphan sections at end of file.
// Other linkers places them using some heuristics as described in
// https://sourceware.org/binutils/docs/ld/Orphan-Sections.html#Orphan-Sections.
for (OutputSectionBase<ELFT> *Sec : *OutputSections) {
StringRef Name = Sec->getName();
if (getSectionIndex(Name) == INT_MAX)
Opt.Commands.push_back(llvm::make_unique<OutputSectionCommand>(Name));
}
// Assign addresses as instructed by linker script SECTIONS sub-commands.
Dot = getHeaderSize();
uintX_t MinVA = std::numeric_limits<uintX_t>::max();
uintX_t ThreadBssOffset = 0;
for (const std::unique_ptr<BaseCommand> &Base : Opt.Commands) {
if (auto *Cmd = dyn_cast<SymbolAssignment>(Base.get())) {
if (Cmd->Name == ".") {
Dot = Cmd->Expression(Dot);
} else if (Cmd->Sym) {
cast<DefinedRegular<ELFT>>(Cmd->Sym)->Value = Cmd->Expression(Dot);
}
continue;
}
if (auto *Cmd = dyn_cast<AssertCommand>(Base.get())) {
Cmd->Expression(Dot);
continue;
}
auto *Cmd = cast<OutputSectionCommand>(Base.get());
OutputSectionBase<ELFT> *Sec = findSection<ELFT>(*Cmd, *OutputSections);
if (!Sec)
continue;
if (Cmd->AddrExpr)
Dot = Cmd->AddrExpr(Dot);
if (Cmd->AlignExpr)
Sec->updateAlignment(Cmd->AlignExpr(Dot));
if ((Sec->getFlags() & SHF_TLS) && Sec->getType() == SHT_NOBITS) {
uintX_t TVA = Dot + ThreadBssOffset;
TVA = alignTo(TVA, Sec->getAlignment());
Sec->setVA(TVA);
assignOffsets(Sec);
ThreadBssOffset = TVA - Dot + Sec->getSize();
continue;
}
if (!(Sec->getFlags() & SHF_ALLOC)) {
Sec->assignOffsets();
continue;
}
Dot = alignTo(Dot, Sec->getAlignment());
Sec->setVA(Dot);
assignOffsets(Sec);
MinVA = std::min(MinVA, Dot);
Dot += Sec->getSize();
}
// ELF and Program headers need to be right before the first section in
// memory. Set their addresses accordingly.
MinVA = alignDown(MinVA - Out<ELFT>::ElfHeader->getSize() -
Out<ELFT>::ProgramHeaders->getSize(),
Target->PageSize);
Out<ELFT>::ElfHeader->setVA(MinVA);
Out<ELFT>::ProgramHeaders->setVA(Out<ELFT>::ElfHeader->getSize() + MinVA);
}
template <class ELFT>
std::vector<PhdrEntry<ELFT>> LinkerScript<ELFT>::createPhdrs() {
ArrayRef<OutputSectionBase<ELFT> *> Sections = *OutputSections;
std::vector<PhdrEntry<ELFT>> Ret;
for (const PhdrsCommand &Cmd : Opt.PhdrsCommands) {
Ret.emplace_back(Cmd.Type, Cmd.Flags == UINT_MAX ? PF_R : Cmd.Flags);
PhdrEntry<ELFT> &Phdr = Ret.back();
if (Cmd.HasFilehdr)
Phdr.add(Out<ELFT>::ElfHeader);
if (Cmd.HasPhdrs)
Phdr.add(Out<ELFT>::ProgramHeaders);
switch (Cmd.Type) {
case PT_INTERP:
if (Out<ELFT>::Interp)
Phdr.add(Out<ELFT>::Interp);
break;
case PT_DYNAMIC:
if (Out<ELFT>::DynSymTab) {
Phdr.H.p_flags = Out<ELFT>::Dynamic->getPhdrFlags();
Phdr.add(Out<ELFT>::Dynamic);
}
break;
case PT_GNU_EH_FRAME:
if (!Out<ELFT>::EhFrame->empty() && Out<ELFT>::EhFrameHdr) {
Phdr.H.p_flags = Out<ELFT>::EhFrameHdr->getPhdrFlags();
Phdr.add(Out<ELFT>::EhFrameHdr);
}
break;
}
}
PhdrEntry<ELFT> *Load = nullptr;
uintX_t Flags = PF_R;
for (OutputSectionBase<ELFT> *Sec : Sections) {
if (!(Sec->getFlags() & SHF_ALLOC))
break;
std::vector<size_t> PhdrIds = getPhdrIndices(Sec->getName());
if (!PhdrIds.empty()) {
// Assign headers specified by linker script
for (size_t Id : PhdrIds) {
Ret[Id].add(Sec);
if (Opt.PhdrsCommands[Id].Flags == UINT_MAX)
Ret[Id].H.p_flags |= Sec->getPhdrFlags();
}
} else {
// If we have no load segment or flags've changed then we want new load
// segment.
uintX_t NewFlags = Sec->getPhdrFlags();
if (Load == nullptr || Flags != NewFlags) {
Load = &*Ret.emplace(Ret.end(), PT_LOAD, NewFlags);
Flags = NewFlags;
}
Load->add(Sec);
}
}
return Ret;
}
template <class ELFT> bool LinkerScript<ELFT>::ignoreInterpSection() {
// Ignore .interp section in case we have PHDRS specification
// and PT_INTERP isn't listed.
return !Opt.PhdrsCommands.empty() &&
llvm::find_if(Opt.PhdrsCommands, [](const PhdrsCommand &Cmd) {
return Cmd.Type == PT_INTERP;
}) == Opt.PhdrsCommands.end();
}
template <class ELFT>
ArrayRef<uint8_t> LinkerScript<ELFT>::getFiller(StringRef Name) {
for (const std::unique_ptr<BaseCommand> &Base : Opt.Commands)
if (auto *Cmd = dyn_cast<OutputSectionCommand>(Base.get()))
if (Cmd->Name == Name)
return Cmd->Filler;
return {};
}
template <class ELFT> Expr LinkerScript<ELFT>::getLma(StringRef Name) {
for (const std::unique_ptr<BaseCommand> &Base : Opt.Commands)
if (auto *Cmd = dyn_cast<OutputSectionCommand>(Base.get()))
if (Cmd->LmaExpr && Cmd->Name == Name)
return Cmd->LmaExpr;
return {};
}
// Returns the index of the given section name in linker script
// SECTIONS commands. Sections are laid out as the same order as they
// were in the script. If a given name did not appear in the script,
// it returns INT_MAX, so that it will be laid out at end of file.
template <class ELFT> int LinkerScript<ELFT>::getSectionIndex(StringRef Name) {
int I = 0;
for (std::unique_ptr<BaseCommand> &Base : Opt.Commands) {
if (auto *Cmd = dyn_cast<OutputSectionCommand>(Base.get()))
if (Cmd->Name == Name)
return I;
++I;
}
return INT_MAX;
}
// A compartor to sort output sections. Returns -1 or 1 if
// A or B are mentioned in linker script. Otherwise, returns 0.
template <class ELFT>
int LinkerScript<ELFT>::compareSections(StringRef A, StringRef B) {
int I = getSectionIndex(A);
int J = getSectionIndex(B);
if (I == INT_MAX && J == INT_MAX)
return 0;
return I < J ? -1 : 1;
}
template <class ELFT> bool LinkerScript<ELFT>::hasPhdrsCommands() {
return !Opt.PhdrsCommands.empty();
}
template <class ELFT>
typename ELFT::uint LinkerScript<ELFT>::getOutputSectionSize(StringRef Name) {
for (OutputSectionBase<ELFT> *Sec : *OutputSections)
if (Sec->getName() == Name)
return Sec->getSize();
error("undefined section " + Name);
return 0;
}
template <class ELFT>
typename ELFT::uint LinkerScript<ELFT>::getHeaderSize() {
return Out<ELFT>::ElfHeader->getSize() + Out<ELFT>::ProgramHeaders->getSize();
}
// Returns indices of ELF headers containing specific section, identified
// by Name. Each index is a zero based number of ELF header listed within
// PHDRS {} script block.
template <class ELFT>
std::vector<size_t> LinkerScript<ELFT>::getPhdrIndices(StringRef SectionName) {
for (const std::unique_ptr<BaseCommand> &Base : Opt.Commands) {
auto *Cmd = dyn_cast<OutputSectionCommand>(Base.get());
if (!Cmd || Cmd->Name != SectionName)
continue;
std::vector<size_t> Ret;
for (StringRef PhdrName : Cmd->Phdrs)
Ret.push_back(getPhdrIndex(PhdrName));
return Ret;
}
return {};
}
template <class ELFT>
size_t LinkerScript<ELFT>::getPhdrIndex(StringRef PhdrName) {
size_t I = 0;
for (PhdrsCommand &Cmd : Opt.PhdrsCommands) {
if (Cmd.Name == PhdrName)
return I;
++I;
}
error("section header '" + PhdrName + "' is not listed in PHDRS");
return 0;
}
class elf::ScriptParser : public ScriptParserBase {
typedef void (ScriptParser::*Handler)();
public:
ScriptParser(StringRef S, bool B) : ScriptParserBase(S), IsUnderSysroot(B) {}
void run();
private:
void addFile(StringRef Path);
void readAsNeeded();
void readEntry();
void readExtern();
void readGroup();
void readInclude();
void readNothing() {}
void readOutput();
void readOutputArch();
void readOutputFormat();
void readPhdrs();
void readSearchDir();
void readSections();
SymbolAssignment *readAssignment(StringRef Name);
OutputSectionCommand *readOutputSectionDescription(StringRef OutSec);
std::vector<uint8_t> readOutputSectionFiller();
std::vector<StringRef> readOutputSectionPhdrs();
InputSectionDescription *readInputSectionDescription();
std::vector<StringRef> readInputFilePatterns();
InputSectionDescription *readInputSectionRules();
unsigned readPhdrType();
SortKind readSortKind();
SymbolAssignment *readProvideHidden(bool Provide, bool Hidden);
SymbolAssignment *readProvideOrAssignment(StringRef Tok);
void readSort();
Expr readAssert();
Expr readExpr();
Expr readExpr1(Expr Lhs, int MinPrec);
Expr readPrimary();
Expr readTernary(Expr Cond);
Expr readParenExpr();
const static StringMap<Handler> Cmd;
ScriptConfiguration &Opt = *ScriptConfig;
StringSaver Saver = {ScriptConfig->Alloc};
bool IsUnderSysroot;
};
const StringMap<elf::ScriptParser::Handler> elf::ScriptParser::Cmd = {
{"ENTRY", &ScriptParser::readEntry},
{"EXTERN", &ScriptParser::readExtern},
{"GROUP", &ScriptParser::readGroup},
{"INCLUDE", &ScriptParser::readInclude},
{"INPUT", &ScriptParser::readGroup},
{"OUTPUT", &ScriptParser::readOutput},
{"OUTPUT_ARCH", &ScriptParser::readOutputArch},
{"OUTPUT_FORMAT", &ScriptParser::readOutputFormat},
{"PHDRS", &ScriptParser::readPhdrs},
{"SEARCH_DIR", &ScriptParser::readSearchDir},
{"SECTIONS", &ScriptParser::readSections},
{";", &ScriptParser::readNothing}};
void ScriptParser::run() {
while (!atEOF()) {
StringRef Tok = next();
if (Handler Fn = Cmd.lookup(Tok))
(this->*Fn)();
else if (SymbolAssignment *Cmd = readProvideOrAssignment(Tok))
Opt.Commands.emplace_back(Cmd);
else
setError("unknown directive: " + Tok);
}
}
void ScriptParser::addFile(StringRef S) {
if (IsUnderSysroot && S.startswith("/")) {
SmallString<128> Path;
(Config->Sysroot + S).toStringRef(Path);
if (sys::fs::exists(Path)) {
Driver->addFile(Saver.save(Path.str()));
return;
}
}
if (sys::path::is_absolute(S)) {
Driver->addFile(S);
} else if (S.startswith("=")) {
if (Config->Sysroot.empty())
Driver->addFile(S.substr(1));
else
Driver->addFile(Saver.save(Config->Sysroot + "/" + S.substr(1)));
} else if (S.startswith("-l")) {
Driver->addLibrary(S.substr(2));
} else if (sys::fs::exists(S)) {
Driver->addFile(S);
} else {
std::string Path = findFromSearchPaths(S);
if (Path.empty())
setError("unable to find " + S);
else
Driver->addFile(Saver.save(Path));
}
}
void ScriptParser::readAsNeeded() {
expect("(");
bool Orig = Config->AsNeeded;
Config->AsNeeded = true;
while (!Error && !skip(")"))
addFile(next());
Config->AsNeeded = Orig;
}
void ScriptParser::readEntry() {
// -e <symbol> takes predecence over ENTRY(<symbol>).
expect("(");
StringRef Tok = next();
if (Config->Entry.empty())
Config->Entry = Tok;
expect(")");
}
void ScriptParser::readExtern() {
expect("(");
while (!Error && !skip(")"))
Config->Undefined.push_back(next());
}
void ScriptParser::readGroup() {
expect("(");
while (!Error && !skip(")")) {
StringRef Tok = next();
if (Tok == "AS_NEEDED")
readAsNeeded();
else
addFile(Tok);
}
}
void ScriptParser::readInclude() {
StringRef Tok = next();
auto MBOrErr = MemoryBuffer::getFile(Tok);
if (!MBOrErr) {
setError("cannot open " + Tok);
return;
}
std::unique_ptr<MemoryBuffer> &MB = *MBOrErr;
StringRef S = Saver.save(MB->getMemBufferRef().getBuffer());
std::vector<StringRef> V = tokenize(S);
Tokens.insert(Tokens.begin() + Pos, V.begin(), V.end());
}
void ScriptParser::readOutput() {
// -o <file> takes predecence over OUTPUT(<file>).
expect("(");
StringRef Tok = next();
if (Config->OutputFile.empty())
Config->OutputFile = Tok;
expect(")");
}
void ScriptParser::readOutputArch() {
// Error checking only for now.
expect("(");
next();
expect(")");
}
void ScriptParser::readOutputFormat() {
// Error checking only for now.
expect("(");
next();
StringRef Tok = next();
if (Tok == ")")
return;
if (Tok != ",") {
setError("unexpected token: " + Tok);
return;
}
next();
expect(",");
next();
expect(")");
}
void ScriptParser::readPhdrs() {
expect("{");
while (!Error && !skip("}")) {
StringRef Tok = next();
Opt.PhdrsCommands.push_back({Tok, PT_NULL, false, false, UINT_MAX});
PhdrsCommand &PhdrCmd = Opt.PhdrsCommands.back();
PhdrCmd.Type = readPhdrType();
do {
Tok = next();
if (Tok == ";")
break;
if (Tok == "FILEHDR")
PhdrCmd.HasFilehdr = true;
else if (Tok == "PHDRS")
PhdrCmd.HasPhdrs = true;
else if (Tok == "FLAGS") {
expect("(");
// Passing 0 for the value of dot is a bit of a hack. It means that
// we accept expressions like ".|1".
PhdrCmd.Flags = readExpr()(0);
expect(")");
} else
setError("unexpected header attribute: " + Tok);
} while (!Error);
}
}
void ScriptParser::readSearchDir() {
expect("(");
Config->SearchPaths.push_back(next());
expect(")");
}
void ScriptParser::readSections() {
Opt.HasContents = true;
expect("{");
while (!Error && !skip("}")) {
StringRef Tok = next();
BaseCommand *Cmd = readProvideOrAssignment(Tok);
if (!Cmd) {
if (Tok == "ASSERT")
Cmd = new AssertCommand(readAssert());
else
Cmd = readOutputSectionDescription(Tok);
}
Opt.Commands.emplace_back(Cmd);
}
}
static int precedence(StringRef Op) {
return StringSwitch<int>(Op)
.Case("*", 4)
.Case("/", 4)
.Case("+", 3)
.Case("-", 3)
.Case("<", 2)
.Case(">", 2)
.Case(">=", 2)
.Case("<=", 2)
.Case("==", 2)
.Case("!=", 2)
.Case("&", 1)
.Default(-1);
}
std::vector<StringRef> ScriptParser::readInputFilePatterns() {
std::vector<StringRef> V;
while (!Error && !skip(")"))
V.push_back(next());
return V;
}
SortKind ScriptParser::readSortKind() {
if (skip("SORT") || skip("SORT_BY_NAME"))
return SortByName;
if (skip("SORT_BY_ALIGNMENT"))
return SortByAlignment;
return SortNone;
}
InputSectionDescription *ScriptParser::readInputSectionRules() {
auto *Cmd = new InputSectionDescription;
Cmd->FilePattern = next();
expect("(");
// Read EXCLUDE_FILE().
if (skip("EXCLUDE_FILE")) {
expect("(");
while (!Error && !skip(")"))
Cmd->ExcludedFiles.push_back(next());
}
// Read SORT().
if (SortKind K1 = readSortKind()) {
Cmd->SortOuter = K1;
expect("(");
if (SortKind K2 = readSortKind()) {
Cmd->SortInner = K2;
expect("(");
Cmd->SectionPatterns = readInputFilePatterns();
expect(")");
} else {
Cmd->SectionPatterns = readInputFilePatterns();
}
expect(")");
return Cmd;
}
Cmd->SectionPatterns = readInputFilePatterns();
return Cmd;
}
InputSectionDescription *ScriptParser::readInputSectionDescription() {
// Input section wildcard can be surrounded by KEEP.
// https://sourceware.org/binutils/docs/ld/Input-Section-Keep.html#Input-Section-Keep
if (skip("KEEP")) {
expect("(");
InputSectionDescription *Cmd = readInputSectionRules();
expect(")");
Opt.KeptSections.insert(Opt.KeptSections.end(),
Cmd->SectionPatterns.begin(),
Cmd->SectionPatterns.end());
return Cmd;
}
return readInputSectionRules();
}
void ScriptParser::readSort() {
expect("(");
expect("CONSTRUCTORS");
expect(")");
}
Expr ScriptParser::readAssert() {
expect("(");
Expr E = readExpr();
expect(",");
StringRef Msg = next();
expect(")");
return [=](uint64_t Dot) {
uint64_t V = E(Dot);
if (!V)
error(Msg);
return V;
};
}
OutputSectionCommand *
ScriptParser::readOutputSectionDescription(StringRef OutSec) {
OutputSectionCommand *Cmd = new OutputSectionCommand(OutSec);
// Read an address expression.
// https://sourceware.org/binutils/docs/ld/Output-Section-Address.html#Output-Section-Address
if (peek() != ":")
Cmd->AddrExpr = readExpr();
expect(":");
if (skip("AT"))
Cmd->LmaExpr = readParenExpr();
if (skip("ALIGN"))
Cmd->AlignExpr = readParenExpr();
if (skip("SUBALIGN"))
Cmd->SubalignExpr = readParenExpr();
// Parse constraints.
if (skip("ONLY_IF_RO"))
Cmd->Constraint = ConstraintKind::ReadOnly;
if (skip("ONLY_IF_RW"))
Cmd->Constraint = ConstraintKind::ReadWrite;
expect("{");
while (!Error && !skip("}")) {
if (peek().startswith("*") || peek() == "KEEP") {
Cmd->Commands.emplace_back(readInputSectionDescription());
continue;
}
StringRef Tok = next();
if (SymbolAssignment *Assignment = readProvideOrAssignment(Tok))
Cmd->Commands.emplace_back(Assignment);
else if (Tok == "SORT")
readSort();
else
setError("unknown command " + Tok);
}
Cmd->Phdrs = readOutputSectionPhdrs();
Cmd->Filler = readOutputSectionFiller();
return Cmd;
}
std::vector<uint8_t> ScriptParser::readOutputSectionFiller() {
StringRef Tok = peek();
if (!Tok.startswith("="))
return {};
next();
// Read a hexstring of arbitrary length.
if (Tok.startswith("=0x"))
return parseHex(Tok.substr(3));
// Read a decimal or octal value as a big-endian 32 bit value.
// Why do this? I don't know, but that's what gold does.
uint32_t V;
if (Tok.substr(1).getAsInteger(0, V)) {
setError("invalid filler expression: " + Tok);
return {};
}
return { uint8_t(V >> 24), uint8_t(V >> 16), uint8_t(V >> 8), uint8_t(V) };
}
SymbolAssignment *ScriptParser::readProvideHidden(bool Provide, bool Hidden) {
expect("(");
SymbolAssignment *Cmd = readAssignment(next());
Cmd->Provide = Provide;
Cmd->Hidden = Hidden;
expect(")");
expect(";");