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COFF: New symbol table design.

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This ports the ELF linker's symbol table design, introduced in r268178,
to the COFF linker.

Differential Revision: http://reviews.llvm.org/D21166

llvm-svn: 289280
This commit is contained in:
Peter Collingbourne
2016-12-09 21:55:24 +00:00
parent 8dc97a4591
commit 79a5e6b1b7
19 changed files with 468 additions and 545 deletions
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4
lld/COFF/Chunks.cpp
View File

@@ -150,7 +150,7 @@ void SectionChunk::writeTo(uint8_t *Buf) const {
// Apply relocations.
for (const coff_relocation &Rel : Relocs) {
uint8_t *Off = Buf + OutputSectionOff + Rel.VirtualAddress;
SymbolBody *Body = File->getSymbolBody(Rel.SymbolTableIndex)->repl();
SymbolBody *Body = File->getSymbolBody(Rel.SymbolTableIndex);
Defined *Sym = cast<Defined>(Body);
uint64_t P = RVA + Rel.VirtualAddress;
switch (Config->Machine) {
@@ -203,7 +203,7 @@ void SectionChunk::getBaserels(std::vector<Baserel> *Res) {
uint8_t Ty = getBaserelType(Rel);
if (Ty == IMAGE_REL_BASED_ABSOLUTE)
continue;
SymbolBody *Body = File->getSymbolBody(Rel.SymbolTableIndex)->repl();
SymbolBody *Body = File->getSymbolBody(Rel.SymbolTableIndex);
if (isa<DefinedAbsolute>(Body))
continue;
Res->emplace_back(RVA + Rel.VirtualAddress, Ty);

1
lld/COFF/Chunks.h
View File

@@ -28,7 +28,6 @@ using llvm::object::COFFSymbolRef;
using llvm::object::SectionRef;
using llvm::object::coff_relocation;
using llvm::object::coff_section;
using llvm::sys::fs::file_magic;
class Baserel;
class Defined;

15
lld/COFF/Config.h
View File

@@ -26,7 +26,8 @@ using llvm::StringRef;
class DefinedAbsolute;
class DefinedRelative;
class StringChunk;
class Undefined;
struct Symbol;
class SymbolBody;
// Short aliases.
static const auto AMD64 = llvm::COFF::IMAGE_FILE_MACHINE_AMD64;
@@ -37,7 +38,7 @@ static const auto I386 = llvm::COFF::IMAGE_FILE_MACHINE_I386;
struct Export {
StringRef Name; // N in /export:N or /export:E=N
StringRef ExtName; // E in /export:E=N
Undefined *Sym = nullptr;
SymbolBody *Sym = nullptr;
uint16_t Ordinal = 0;
bool Noname = false;
bool Data = false;
@@ -76,7 +77,7 @@ struct Configuration {
llvm::COFF::MachineTypes Machine = IMAGE_FILE_MACHINE_UNKNOWN;
bool Verbose = false;
WindowsSubsystem Subsystem = llvm::COFF::IMAGE_SUBSYSTEM_UNKNOWN;
Undefined *Entry = nullptr;
SymbolBody *Entry = nullptr;
bool NoEntry = false;
std::string OutputFile;
bool DoGC = true;
@@ -89,7 +90,7 @@ struct Configuration {
StringRef PDBPath;
// Symbols in this set are considered as live by the garbage collector.
std::set<Undefined *> GCRoot;
std::set<SymbolBody *> GCRoot;
std::set<StringRef> NoDefaultLibs;
bool NoDefaultLibAll = false;
@@ -100,11 +101,11 @@ struct Configuration {
std::vector<Export> Exports;
std::set<std::string> DelayLoads;
std::map<std::string, int> DLLOrder;
Undefined *DelayLoadHelper = nullptr;
SymbolBody *DelayLoadHelper = nullptr;
// Used for SafeSEH.
DefinedRelative *SEHTable = nullptr;
DefinedAbsolute *SEHCount = nullptr;
Symbol *SEHTable = nullptr;
Symbol *SEHCount = nullptr;
// Used for /opt:lldlto=N
unsigned LTOOptLevel = 2;

2
lld/COFF/DLL.cpp
View File

@@ -324,7 +324,7 @@ public:
if (E.ForwardChunk) {
write32le(P, E.ForwardChunk->getRVA());
} else {
write32le(P, cast<Defined>(E.Sym->repl())->getRVA());
write32le(P, cast<Defined>(E.Sym)->getRVA());
}
}
}

14
lld/COFF/Driver.cpp
View File

@@ -207,10 +207,10 @@ void LinkerDriver::addLibSearchPaths() {
}
}
Undefined *LinkerDriver::addUndefined(StringRef Name) {
Undefined *U = Symtab.addUndefined(Name);
Config->GCRoot.insert(U);
return U;
SymbolBody *LinkerDriver::addUndefined(StringRef Name) {
SymbolBody *B = Symtab.addUndefined(Name);
Config->GCRoot.insert(B);
return B;
}
// Symbol names are mangled by appending "_" prefix on x86.
@@ -232,7 +232,7 @@ StringRef LinkerDriver::findDefaultEntry() {
};
for (auto E : Entries) {
StringRef Entry = Symtab.findMangle(mangle(E[0]));
if (!Entry.empty() && !isa<Undefined>(Symtab.find(Entry)->Body))
if (!Entry.empty() && !isa<Undefined>(Symtab.find(Entry)->body()))
return mangle(E[1]);
}
return "";
@@ -715,7 +715,7 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
Symbol *Sym = Symtab.find(From);
if (!Sym)
continue;
if (auto *U = dyn_cast<Undefined>(Sym->Body))
if (auto *U = dyn_cast<Undefined>(Sym->body()))
if (!U->WeakAlias)
U->WeakAlias = Symtab.addUndefined(To);
}
@@ -734,7 +734,7 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
Symtab.addCombinedLTOObjects();
// Make sure we have resolved all symbols.
Symtab.reportRemainingUndefines(/*Resolve=*/true);
Symtab.reportRemainingUndefines();
// Windows specific -- if no /subsystem is given, we need to infer
// that from entry point name.

3
lld/COFF/Driver.h
View File

@@ -59,6 +59,7 @@ private:
class LinkerDriver {
public:
LinkerDriver() { coff::Symtab = &Symtab; }
void link(llvm::ArrayRef<const char *> Args);
// Used by the resolver to parse .drectve section contents.
@@ -86,7 +87,7 @@ private:
std::vector<StringRef> SearchPaths;
std::set<std::string> VisitedFiles;
Undefined *addUndefined(StringRef Sym);
SymbolBody *addUndefined(StringRef Sym);
StringRef mangle(StringRef Sym);
// Windows specific -- "main" is not the only main function in Windows.

10
lld/COFF/DriverUtils.cpp
View File

@@ -510,13 +510,13 @@ void fixupExports() {
}
for (Export &E : Config->Exports) {
SymbolBody *Sym = E.Sym;
if (!E.ForwardTo.empty()) {
E.SymbolName = E.Name;
} else if (Undefined *U = cast_or_null<Undefined>(E.Sym->WeakAlias)) {
E.SymbolName = U->getName();
} else {
E.SymbolName = E.Sym->getName();
}
} else if (auto *U = dyn_cast<Undefined>(Sym))
if (U->WeakAlias)
Sym = U->WeakAlias;
E.SymbolName = Sym->getName();
}
for (Export &E : Config->Exports) {

8
lld/COFF/ICF.cpp
View File

@@ -115,8 +115,8 @@ bool ICF::equalsConstant(const SectionChunk *A, const SectionChunk *B) {
R1.VirtualAddress != R2.VirtualAddress) {
return false;
}
SymbolBody *B1 = A->File->getSymbolBody(R1.SymbolTableIndex)->repl();
SymbolBody *B2 = B->File->getSymbolBody(R2.SymbolTableIndex)->repl();
SymbolBody *B1 = A->File->getSymbolBody(R1.SymbolTableIndex);
SymbolBody *B2 = B->File->getSymbolBody(R2.SymbolTableIndex);
if (B1 == B2)
return true;
if (auto *D1 = dyn_cast<DefinedRegular>(B1))
@@ -141,8 +141,8 @@ bool ICF::equalsConstant(const SectionChunk *A, const SectionChunk *B) {
bool ICF::equalsVariable(const SectionChunk *A, const SectionChunk *B) {
// Compare relocations.
auto Eq = [&](const coff_relocation &R1, const coff_relocation &R2) {
SymbolBody *B1 = A->File->getSymbolBody(R1.SymbolTableIndex)->repl();
SymbolBody *B2 = B->File->getSymbolBody(R2.SymbolTableIndex)->repl();
SymbolBody *B1 = A->File->getSymbolBody(R1.SymbolTableIndex);
SymbolBody *B2 = B->File->getSymbolBody(R2.SymbolTableIndex);
if (B1 == B2)
return true;
if (auto *D1 = dyn_cast<DefinedRegular>(B1))

96
lld/COFF/InputFiles.cpp
View File

@@ -12,7 +12,9 @@
#include "Driver.h"
#include "Error.h"
#include "InputFiles.h"
#include "SymbolTable.h"
#include "Symbols.h"
#include "lld/Support/Memory.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
@@ -39,13 +41,13 @@ using namespace llvm::support::endian;
using llvm::Triple;
using llvm::support::ulittle32_t;
using llvm::sys::fs::file_magic;
using llvm::sys::fs::identify_magic;
namespace lld {
namespace coff {
int InputFile::NextIndex = 0;
LLVMContext BitcodeFile::Context;
std::mutex BitcodeFile::Mu;
ArchiveFile::ArchiveFile(MemoryBufferRef M) : InputFile(ArchiveKind, M) {}
@@ -53,14 +55,6 @@ void ArchiveFile::parse() {
// Parse a MemoryBufferRef as an archive file.
File = check(Archive::create(MB), toString(this));
// Allocate a buffer for Lazy objects.
size_t NumSyms = File->getNumberOfSymbols();
LazySymbols.reserve(NumSyms);
// Read the symbol table to construct Lazy objects.
for (const Archive::Symbol &Sym : File->symbols())
LazySymbols.emplace_back(this, Sym);
// Seen is a map from member files to boolean values. Initially
// all members are mapped to false, which indicates all these files
// are not read yet.
@@ -69,18 +63,22 @@ void ArchiveFile::parse() {
Seen[Child.getChildOffset()].clear();
if (Err)
fatal(Err, toString(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.
// This function is thread-safe.
MemoryBufferRef ArchiveFile::getMember(const Archive::Symbol *Sym) {
InputFile *ArchiveFile::getMember(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[C.getChildOffset()].test_and_set())
return MemoryBufferRef();
return nullptr;
MemoryBufferRef MB =
check(C.getMemoryBufferRef(),
@@ -90,10 +88,21 @@ MemoryBufferRef ArchiveFile::getMember(const Archive::Symbol *Sym) {
Driver->Cpio->append(relativeToRoot(check(C.getFullName())),
MB.getBuffer());
return MB;
}
file_magic Magic = identify_magic(MB.getBuffer());
if (Magic == file_magic::coff_import_library)
return make<ImportFile>(MB);
MutableArrayRef<Lazy> ArchiveFile::getLazySymbols() { return LazySymbols; }
InputFile *Obj;
if (Magic == file_magic::coff_object)
Obj = make<ObjectFile>(MB);
else if (Magic == file_magic::bitcode)
Obj = make<BitcodeFile>(MB);
else
fatal("unknown file type: " + MB.getBufferIdentifier());
Obj->ParentName = getName();
return Obj;
}
void ObjectFile::parse() {
// Parse a memory buffer as a COFF file.
@@ -167,7 +176,7 @@ void ObjectFile::initializeSymbols() {
uint32_t NumSymbols = COFFObj->getNumberOfSymbols();
SymbolBodies.reserve(NumSymbols);
SparseSymbolBodies.resize(NumSymbols);
SmallVector<std::pair<Undefined *, uint32_t>, 8> WeakAliases;
SmallVector<std::pair<SymbolBody *, uint32_t>, 8> WeakAliases;
int32_t LastSectionNumber = 0;
for (uint32_t I = 0; I < NumSymbols; ++I) {
// Get a COFFSymbolRef object.
@@ -188,7 +197,7 @@ void ObjectFile::initializeSymbols() {
Body = createUndefined(Sym);
uint32_t TagIndex =
static_cast<const coff_aux_weak_external *>(AuxP)->TagIndex;
WeakAliases.emplace_back((Undefined *)Body, TagIndex);
WeakAliases.emplace_back(Body, TagIndex);
} else {
Body = createDefined(Sym, AuxP, IsFirst);
}
@@ -199,23 +208,30 @@ void ObjectFile::initializeSymbols() {
I += Sym.getNumberOfAuxSymbols();
LastSectionNumber = Sym.getSectionNumber();
}
for (auto WeakAlias : WeakAliases)
WeakAlias.first->WeakAlias = SparseSymbolBodies[WeakAlias.second];
for (auto WeakAlias : WeakAliases) {
auto *U = dyn_cast<Undefined>(WeakAlias.first);
if (!U)
continue;
// Report an error if two undefined symbols have different weak aliases.
if (U->WeakAlias && U->WeakAlias != SparseSymbolBodies[WeakAlias.second])
Symtab->reportDuplicate(U->symbol(), this);
U->WeakAlias = SparseSymbolBodies[WeakAlias.second];
}
}
Undefined *ObjectFile::createUndefined(COFFSymbolRef Sym) {
SymbolBody *ObjectFile::createUndefined(COFFSymbolRef Sym) {
StringRef Name;
COFFObj->getSymbolName(Sym, Name);
return new (Alloc) Undefined(Name);
return Symtab->addUndefined(Name, this, Sym.isWeakExternal())->body();
}
Defined *ObjectFile::createDefined(COFFSymbolRef Sym, const void *AuxP,
bool IsFirst) {
SymbolBody *ObjectFile::createDefined(COFFSymbolRef Sym, const void *AuxP,
bool IsFirst) {
StringRef Name;
if (Sym.isCommon()) {
auto *C = new (Alloc) CommonChunk(Sym);
Chunks.push_back(C);
return new (Alloc) DefinedCommon(this, Sym, C);
return Symtab->addCommon(this, Sym, C)->body();
}
if (Sym.isAbsolute()) {
COFFObj->getSymbolName(Sym, Name);
@@ -228,7 +244,10 @@ Defined *ObjectFile::createDefined(COFFSymbolRef Sym, const void *AuxP,
SEHCompat = true;
return nullptr;
}
return new (Alloc) DefinedAbsolute(Name, Sym);
if (Sym.isExternal())
return Symtab->addAbsolute(Name, Sym)->body();
else
return new (Alloc) DefinedAbsolute(Name, Sym);
}
int32_t SectionNumber = Sym.getSectionNumber();
if (SectionNumber == llvm::COFF::IMAGE_SYM_DEBUG)
@@ -258,7 +277,11 @@ Defined *ObjectFile::createDefined(COFFSymbolRef Sym, const void *AuxP,
SC->Checksum = Aux->CheckSum;
}
auto *B = new (Alloc) DefinedRegular(this, Sym, SC);
DefinedRegular *B;
if (Sym.isExternal())
B = cast<DefinedRegular>(Symtab->addRegular(this, Sym, SC)->body());
else
B = new (Alloc) DefinedRegular(this, Sym, SC);
if (SC->isCOMDAT() && Sym.getValue() == 0 && !AuxP)
SC->setSymbol(B);
@@ -320,22 +343,23 @@ void ImportFile::parse() {
ExtName = ExtName.substr(0, ExtName.find('@'));
break;
}
ImpSym = new (Alloc) DefinedImportData(DLLName, ImpName, ExtName, Hdr);
SymbolBodies.push_back(ImpSym);
this->Hdr = Hdr;
ExternalName = ExtName;
ImpSym = cast<DefinedImportData>(
Symtab->addImportData(ImpName, this)->body());
// 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)
return;
ThunkSym = new (Alloc) DefinedImportThunk(Name, ImpSym, Hdr->Machine);
SymbolBodies.push_back(ThunkSym);
ThunkSym = cast<DefinedImportThunk>(
Symtab->addImportThunk(Name, ImpSym, Hdr->Machine)->body());
}
void BitcodeFile::parse() {
// Usually parse() is thread-safe, but bitcode file is an exception.
std::lock_guard<std::mutex> Lock(Mu);
Context.enableDebugTypeODRUniquing();
ErrorOr<std::unique_ptr<LTOModule>> ModOrErr = LTOModule::createFromBuffer(
Context, MB.getBufferStart(), MB.getBufferSize(), llvm::TargetOptions());
@@ -350,15 +374,15 @@ void BitcodeFile::parse() {
StringRef SymName = Saver.save(M->getSymbolName(I));
int SymbolDef = Attrs & LTO_SYMBOL_DEFINITION_MASK;
if (SymbolDef == LTO_SYMBOL_DEFINITION_UNDEFINED) {
SymbolBodies.push_back(new (Alloc) Undefined(SymName));
SymbolBodies.push_back(Symtab->addUndefined(SymName, this, false)->body());
} else {
bool Replaceable =
(SymbolDef == LTO_SYMBOL_DEFINITION_TENTATIVE || // common
(Attrs & LTO_SYMBOL_COMDAT) || // comdat
(SymbolDef == LTO_SYMBOL_DEFINITION_WEAK && // weak external
(Attrs & LTO_SYMBOL_ALIAS)));
SymbolBodies.push_back(new (Alloc) DefinedBitcode(this, SymName,
Replaceable));
SymbolBodies.push_back(
Symtab->addBitcode(this, SymName, Replaceable)->body());
}
}

44
lld/COFF/InputFiles.h
View File

@@ -31,6 +31,7 @@ using llvm::COFF::MachineTypes;
using llvm::object::Archive;
using llvm::object::COFFObjectFile;
using llvm::object::COFFSymbolRef;
using llvm::object::coff_import_header;
using llvm::object::coff_section;
class Chunk;
@@ -39,6 +40,7 @@ class DefinedImportData;
class DefinedImportThunk;
class Lazy;
class SectionChunk;
struct Symbol;
class SymbolBody;
class Undefined;
@@ -52,9 +54,6 @@ public:
// Returns the filename.
StringRef getName() { return MB.getBufferIdentifier(); }
// Returns symbols defined by this file.
virtual std::vector<SymbolBody *> &getSymbols() = 0;
// Reads a file (the constructor doesn't do that).
virtual void parse() = 0;
@@ -67,14 +66,8 @@ public:
// Returns .drectve section contents if exist.
StringRef getDirectives() { return StringRef(Directives).trim(); }
// Each file has a unique index. The index number is used to
// resolve ties in symbol resolution.
int Index;
static int NextIndex;
protected:
InputFile(Kind K, MemoryBufferRef M)
: Index(NextIndex++), MB(M), FileKind(K) {}
InputFile(Kind K, MemoryBufferRef M) : MB(M), FileKind(K) {}
MemoryBufferRef MB;
std::string Directives;
@@ -90,22 +83,14 @@ public:
static bool classof(const InputFile *F) { return F->kind() == ArchiveKind; }
void parse() override;
// Returns a memory buffer for a given symbol. An empty memory buffer
// is returned if we have already returned the same memory buffer.
// (So that we don't instantiate same members more than once.)
MemoryBufferRef getMember(const Archive::Symbol *Sym);
llvm::MutableArrayRef<Lazy> getLazySymbols();
// All symbols returned by ArchiveFiles are of Lazy type.
std::vector<SymbolBody *> &getSymbols() override {
llvm_unreachable("internal fatal");
}
// Returns an input file for a given symbol. A null pointer is returned if we
// have already returned the same input file. (So that we don't instantiate
// the same member more than once.)
InputFile *getMember(const Archive::Symbol *Sym);
private:
std::unique_ptr<Archive> File;
std::string Filename;
std::vector<Lazy> LazySymbols;
std::map<uint64_t, std::atomic_flag> Seen;
};
@@ -118,7 +103,7 @@ public:
MachineTypes getMachineType() override;
std::vector<Chunk *> &getChunks() { return Chunks; }
std::vector<SectionChunk *> &getDebugChunks() { return DebugChunks; }
std::vector<SymbolBody *> &getSymbols() override { return SymbolBodies; }
std::vector<SymbolBody *> &getSymbols() { return SymbolBodies; }
// Returns a SymbolBody object for the SymbolIndex'th symbol in the
// underlying object file.
@@ -142,8 +127,8 @@ private:
void initializeSymbols();
void initializeSEH();
Defined *createDefined(COFFSymbolRef Sym, const void *Aux, bool IsFirst);
Undefined *createUndefined(COFFSymbolRef Sym);
SymbolBody *createDefined(COFFSymbolRef Sym, const void *Aux, bool IsFirst);
SymbolBody *createUndefined(COFFSymbolRef Sym);
std::unique_ptr<COFFObjectFile> COFFObj;
llvm::BumpPtrAllocator Alloc;
@@ -181,7 +166,6 @@ public:
explicit ImportFile(MemoryBufferRef M)
: InputFile(ImportKind, M), StringAlloc(StringAllocAux) {}
static bool classof(const InputFile *F) { return F->kind() == ImportKind; }
std::vector<SymbolBody *> &getSymbols() override { return SymbolBodies; }
DefinedImportData *ImpSym = nullptr;
DefinedImportThunk *ThunkSym = nullptr;
@@ -190,10 +174,14 @@ public:
private:
void parse() override;
std::vector<SymbolBody *> SymbolBodies;
llvm::BumpPtrAllocator Alloc;
llvm::BumpPtrAllocator StringAllocAux;
llvm::StringSaver StringAlloc;
public:
StringRef ExternalName;
const coff_import_header *Hdr;
Chunk *Location = nullptr;
};
// Used for LTO.
@@ -201,7 +189,7 @@ class BitcodeFile : public InputFile {
public:
explicit BitcodeFile(MemoryBufferRef M) : InputFile(BitcodeKind, M) {}
static bool classof(const InputFile *F) { return F->kind() == BitcodeKind; }
std::vector<SymbolBody *> &getSymbols() override { return SymbolBodies; }
std::vector<SymbolBody *> &getSymbols() { return SymbolBodies; }
MachineTypes getMachineType() override;
std::unique_ptr<LTOModule> takeModule() { return std::move(M); }

6
lld/COFF/MarkLive.cpp
View File

@@ -38,8 +38,8 @@ void markLive(const std::vector<Chunk *> &Chunks) {
};
// Add GC root chunks.
for (Undefined *U : Config->GCRoot)
if (auto *D = dyn_cast<DefinedRegular>(U->repl()))
for (SymbolBody *B : Config->GCRoot)
if (auto *D = dyn_cast<DefinedRegular>(B))
Enqueue(D->getChunk());
while (!Worklist.empty()) {
@@ -48,7 +48,7 @@ void markLive(const std::vector<Chunk *> &Chunks) {
// Mark all symbols listed in the relocation table for this section.
for (SymbolBody *S : SC->symbols())
if (auto *D = dyn_cast<DefinedRegular>(S->repl()))
if (auto *D = dyn_cast<DefinedRegular>(S))
Enqueue(D->getChunk());
// Mark associative sections if any.

416
lld/COFF/SymbolTable.cpp
View File

@@ -12,7 +12,6 @@
#include "Driver.h"
#include "Error.h"
#include "Symbols.h"
#include "lld/Core/Parallel.h"
#include "lld/Support/Memory.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/LTO/legacy/LTOCodeGenerator.h"
@@ -25,21 +24,15 @@ using namespace llvm;
namespace lld {
namespace coff {
void SymbolTable::addFile(InputFile *File) {
#if LLVM_ENABLE_THREADS
std::launch Policy = std::launch::async;
#else
std::launch Policy = std::launch::deferred;
#endif
SymbolTable *Symtab;
void SymbolTable::addFile(InputFile *File) {
Files.push_back(File);
if (auto *F = dyn_cast<ArchiveFile>(File)) {
ArchiveQueue.push_back(
std::async(Policy, [=]() { F->parse(); return F; }));
ArchiveQueue.push_back(F);
return;
}
ObjectQueue.push_back(
std::async(Policy, [=]() { File->parse(); return File; }));
ObjectQueue.push_back(File);
if (auto *F = dyn_cast<ObjectFile>(File)) {
ObjectFiles.push_back(F);
} else if (auto *F = dyn_cast<BitcodeFile>(File)) {
@@ -53,7 +46,7 @@ void SymbolTable::step() {
if (queueEmpty())
return;
readObjects();
readArchives();
readArchive();
}
void SymbolTable::run() {
@@ -61,26 +54,17 @@ void SymbolTable::run() {
step();
}
void SymbolTable::readArchives() {
void SymbolTable::readArchive() {
if (ArchiveQueue.empty())
return;
// Add lazy symbols to the symbol table. Lazy symbols that conflict
// with existing undefined symbols are accumulated in LazySyms.
std::vector<Symbol *> LazySyms;
for (std::future<ArchiveFile *> &Future : ArchiveQueue) {
ArchiveFile *File = Future.get();
if (Config->Verbose)
outs() << "Reading " << toString(File) << "\n";
for (Lazy &Sym : File->getLazySymbols())
addLazy(&Sym, &LazySyms);
}
ArchiveQueue.clear();
// Add archive member files to ObjectQueue that should resolve
// existing undefined symbols.
for (Symbol *Sym : LazySyms)
addMemberFile(cast<Lazy>(Sym->Body));
ArchiveFile *File = ArchiveQueue.front();
ArchiveQueue.pop_front();
if (Config->Verbose)
outs() << "Reading " << toString(File) << "\n";
File->parse();
}
void SymbolTable::readObjects() {
@@ -90,14 +74,12 @@ void SymbolTable::readObjects() {
// Add defined and undefined symbols to the symbol table.
std::vector<StringRef> Directives;
for (size_t I = 0; I < ObjectQueue.size(); ++I) {
InputFile *File = ObjectQueue[I].get();
InputFile *File = ObjectQueue[I];
if (Config->Verbose)
outs() << "Reading " << toString(File) << "\n";
File->parse();
// Adding symbols may add more files to ObjectQueue
// (but not to ArchiveQueue).
for (SymbolBody *Sym : File->getSymbols())
if (Sym->isExternal())
addSymbol(Sym);
StringRef S = File->getDirectives();
if (!S.empty()) {
Directives.push_back(S);
@@ -117,127 +99,239 @@ bool SymbolTable::queueEmpty() {
return ArchiveQueue.empty() && ObjectQueue.empty();
}
void SymbolTable::reportRemainingUndefines(bool Resolve) {
void SymbolTable::reportRemainingUndefines() {
SmallPtrSet<SymbolBody *, 8> Undefs;
for (auto &I : Symtab) {
Symbol *Sym = I.second;
auto *Undef = dyn_cast<Undefined>(Sym->Body);
auto *Undef = dyn_cast<Undefined>(Sym->body());
if (!Undef)
continue;
if (!Sym->IsUsedInRegularObj)
continue;
StringRef Name = Undef->getName();
// A weak alias may have been resolved, so check for that.
if (Defined *D = Undef->getWeakAlias()) {
if (Resolve)
Sym->Body = D;
// We resolve weak aliases by replacing the alias's SymbolBody with the
// target's SymbolBody. This causes all SymbolBody pointers referring to
// the old symbol to instead refer to the new symbol. However, we can't
// just blindly copy sizeof(Symbol::Body) bytes from D to Sym->Body
// because D may be an internal symbol, and internal symbols are stored as
// "unparented" SymbolBodies. For that reason we need to check which type
// of symbol we are dealing with and copy the correct number of bytes.
if (isa<DefinedRegular>(D))
memcpy(Sym->Body.buffer, D, sizeof(DefinedRegular));
else if (isa<DefinedAbsolute>(D))
memcpy(Sym->Body.buffer, D, sizeof(DefinedAbsolute));
else
// No other internal symbols are possible.
Sym->Body = D->symbol()->Body;
continue;
}
// If we can resolve a symbol by removing __imp_ prefix, do that.
// This odd rule is for compatibility with MSVC linker.
if (Name.startswith("__imp_")) {
Symbol *Imp = find(Name.substr(strlen("__imp_")));
if (Imp && isa<Defined>(Imp->Body)) {
if (!Resolve)
continue;
auto *D = cast<Defined>(Imp->Body);
auto *S = make<DefinedLocalImport>(Name, D);
LocalImportChunks.push_back(S->getChunk());
Sym->Body = S;
if (Imp && isa<Defined>(Imp->body())) {
auto *D = cast<Defined>(Imp->body());
replaceBody<DefinedLocalImport>(Sym, Name, D);
LocalImportChunks.push_back(
cast<DefinedLocalImport>(Sym->body())->getChunk());
continue;
}
}
// Remaining undefined symbols are not fatal if /force is specified.
// They are replaced with dummy defined symbols.
if (Config->Force && Resolve)
Sym->Body = make<DefinedAbsolute>(Name, 0);
Undefs.insert(Sym->Body);
if (Config->Force)
replaceBody<DefinedAbsolute>(Sym, Name, 0);
Undefs.insert(Sym->body());
}
if (Undefs.empty())
return;
for (Undefined *U : Config->GCRoot)
if (Undefs.count(U->repl()))
errs() << "<root>: undefined symbol: " << U->getName() << "\n";
for (InputFile *File : Files)
if (!isa<ArchiveFile>(File))
for (SymbolBody *Sym : File->getSymbols())
if (Undefs.count(Sym->repl()))
errs() << toString(File) << ": undefined symbol: " << Sym->getName()
<< "\n";
for (SymbolBody *B : Config->GCRoot)
if (Undefs.count(B))
errs() << "<root>: undefined symbol: " << B->getName() << "\n";
for (ObjectFile *File : ObjectFiles)
for (SymbolBody *Sym : File->getSymbols())
if (Undefs.count(Sym))
errs() << toString(File) << ": undefined symbol: " << Sym->getName()
<< "\n";
if (!Config->Force)
fatal("link failed");
}
void SymbolTable::addLazy(Lazy *New, std::vector<Symbol *> *Accum) {
Symbol *Sym = insert(New);
if (Sym->Body == New)
return;
SymbolBody *Existing = Sym->Body;
if (isa<Defined>(Existing))
return;
if (Lazy *L = dyn_cast<Lazy>(Existing))
if (L->getFileIndex() < New->getFileIndex())
return;
Sym->Body = New;
New->setBackref(Sym);
if (isa<Undefined>(Existing))
Accum->push_back(Sym);
std::pair<Symbol *, bool> SymbolTable::insert(StringRef Name) {
Symbol *&Sym = Symtab[Name];
if (Sym)
return {Sym, false};
Sym = make<Symbol>();
Sym->IsUsedInRegularObj = false;
return {Sym, true};
}
void SymbolTable::addSymbol(SymbolBody *New) {
// Find an existing symbol or create and insert a new one.
assert(isa<Defined>(New) || isa<Undefined>(New));
Symbol *Sym = insert(New);
if (Sym->Body == New)
return;
SymbolBody *Existing = Sym->Body;
// If we have an undefined symbol and a lazy symbol,
// let the lazy symbol to read a member file.
if (auto *L = dyn_cast<Lazy>(Existing)) {
// Undefined symbols with weak aliases need not to be resolved,
// since they would be replaced with weak aliases if they remain
// undefined.
if (auto *U = dyn_cast<Undefined>(New)) {
if (!U->WeakAlias) {
addMemberFile(L);
return;
}
}
Sym->Body = New;
return;
Symbol *SymbolTable::addUndefined(StringRef Name, InputFile *F,
bool IsWeakAlias) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Name);
if (!F || !isa<BitcodeFile>(F))
S->IsUsedInRegularObj = true;
if (WasInserted || (isa<Lazy>(S->body()) && IsWeakAlias)) {
replaceBody<Undefined>(S, Name);
return S;
}
// compare() returns -1, 0, or 1 if the lhs symbol is less preferable,
// equivalent (conflicting), or more preferable, respectively.
int Comp = Existing->compare(New);
if (Comp == 0)
fatal("duplicate symbol: " + toString(*Existing) + " in " +
toString(Existing->getFile()) + " and in " +
toString(New->getFile()));
if (Comp < 0)
Sym->Body = New;
if (auto *L = dyn_cast<Lazy>(S->body()))
addMemberFile(L->File, L->Sym);
return S;
}
Symbol *SymbolTable::insert(SymbolBody *New) {
Symbol *&Sym = Symtab[New->getName()];
if (Sym) {
New->setBackref(Sym);
return Sym;
void SymbolTable::addLazy(ArchiveFile *F, const Archive::Symbol Sym) {
StringRef Name = Sym.getName();
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Name);
if (WasInserted) {
replaceBody<Lazy>(S, F, Sym);
return;
}
Sym = make<Symbol>(New);
New->setBackref(Sym);
return Sym;
auto *U = dyn_cast<Undefined>(S->body());
if (!U || U->WeakAlias)
return;
addMemberFile(F, Sym);
}
void SymbolTable::reportDuplicate(Symbol *Existing, InputFile *NewFile) {
fatal("duplicate symbol: " + toString(*Existing->body()) + " in " +
toString(Existing->body()->getFile()) + " and in " +
(NewFile ? toString(NewFile) : "(internal)"));
}
Symbol *SymbolTable::addAbsolute(StringRef N, COFFSymbolRef Sym) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(N);
S->IsUsedInRegularObj = true;
if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
replaceBody<DefinedAbsolute>(S, N, Sym);
else if (!isa<DefinedCOFF>(S->body()))
reportDuplicate(S, nullptr);
return S;
}
Symbol *SymbolTable::addAbsolute(StringRef N, uint64_t VA) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(N);
S->IsUsedInRegularObj = true;
if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
replaceBody<DefinedAbsolute>(S, N, VA);
else if (!isa<DefinedCOFF>(S->body()))
reportDuplicate(S, nullptr);
return S;
}
Symbol *SymbolTable::addRelative(StringRef N, uint64_t VA) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(N);
S->IsUsedInRegularObj = true;
if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
replaceBody<DefinedRelative>(S, N, VA);
else if (!isa<DefinedCOFF>(S->body()))
reportDuplicate(S, nullptr);
return S;
}
Symbol *SymbolTable::addRegular(ObjectFile *F, COFFSymbolRef Sym,
SectionChunk *C) {
StringRef Name;
F->getCOFFObj()->getSymbolName(Sym, Name);
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Name);
S->IsUsedInRegularObj = true;
if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
replaceBody<DefinedRegular>(S, F, Sym, C);
else if (auto *R = dyn_cast<DefinedRegular>(S->body())) {
if (!C->isCOMDAT() || !R->isCOMDAT())
reportDuplicate(S, F);
} else if (auto *B = dyn_cast<DefinedBitcode>(S->body())) {
if (B->IsReplaceable)
replaceBody<DefinedRegular>(S, F, Sym, C);
else if (!C->isCOMDAT())
reportDuplicate(S, F);
} else
replaceBody<DefinedRegular>(S, F, Sym, C);
return S;
}
Symbol *SymbolTable::addBitcode(BitcodeFile *F, StringRef N, bool IsReplaceable) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(N);
if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body())) {
replaceBody<DefinedBitcode>(S, F, N, IsReplaceable);
return S;
}
if (isa<DefinedCommon>(S->body()))
return S;
if (IsReplaceable)
if (isa<DefinedRegular>(S->body()) || isa<DefinedBitcode>(S->body()))
return S;
reportDuplicate(S, F);
return S;
}
Symbol *SymbolTable::addCommon(ObjectFile *F, COFFSymbolRef Sym,
CommonChunk *C) {
StringRef Name;
F->getCOFFObj()->getSymbolName(Sym, Name);
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Name);
S->IsUsedInRegularObj = true;
if (WasInserted || !isa<DefinedCOFF>(S->body()))
replaceBody<DefinedCommon>(S, F, Sym, C);
else if (auto *DC = dyn_cast<DefinedCommon>(S->body()))
if (Sym.getValue() > DC->getSize())
replaceBody<DefinedCommon>(S, F, Sym, C);
return S;
}
Symbol *SymbolTable::addImportData(StringRef N, ImportFile *F) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(N);
S->IsUsedInRegularObj = true;
if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
replaceBody<DefinedImportData>(S, N, F);
else if (!isa<DefinedCOFF>(S->body()))
reportDuplicate(S, nullptr);
return S;
}
Symbol *SymbolTable::addImportThunk(StringRef Name, DefinedImportData *ID,
uint16_t Machine) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Name);
S->IsUsedInRegularObj = true;
if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
replaceBody<DefinedImportThunk>(S, Name, ID, Machine);
else if (!isa<DefinedCOFF>(S->body()))
reportDuplicate(S, nullptr);
return S;
}
// Reads an archive member file pointed by a given symbol.
void SymbolTable::addMemberFile(Lazy *Body) {
InputFile *File = Body->getMember();
void SymbolTable::addMemberFile(ArchiveFile *F, const Archive::Symbol Sym) {
InputFile *File = F->getMember(&Sym);
// getMember returns an empty buffer if the member was already
// read from the library.
if (!File)
return;
if (Config->Verbose)
outs() << "Loaded " << toString(File) << " for " << Body->getName() << "\n";
outs() << "Loaded " << toString(File) << " for " << Sym.getName() << "\n";
addFile(File);
}
@@ -274,7 +368,7 @@ StringRef SymbolTable::findByPrefix(StringRef Prefix) {
StringRef SymbolTable::findMangle(StringRef Name) {
if (Symbol *Sym = find(Name))
if (!isa<Undefined>(Sym->Body))
if (!isa<Undefined>(Sym->body()))
return Name;
if (Config->Machine != I386)
return findByPrefix(("?" + Name + "@@Y").str());
@@ -288,34 +382,17 @@ StringRef SymbolTable::findMangle(StringRef Name) {
return findByPrefix(("?" + Name.substr(1) + "@@Y").str());
}
void SymbolTable::mangleMaybe(Undefined *U) {
if (U->WeakAlias)
return;
if (!isa<Undefined>(U->repl()))
void SymbolTable::mangleMaybe(SymbolBody *B) {
auto *U = dyn_cast<Undefined>(B);
if (!U || U->WeakAlias)
return;
StringRef Alias = findMangle(U->getName());
if (!Alias.empty())
U->WeakAlias = addUndefined(Alias);
}
Undefined *SymbolTable::addUndefined(StringRef Name) {
auto *New = make<Undefined>(Name);
addSymbol(New);
if (auto *U = dyn_cast<Undefined>(New->repl()))
return U;
return New;
}
DefinedRelative *SymbolTable::addRelative(StringRef Name, uint64_t VA) {
auto *New = make<DefinedRelative>(Name, VA);
addSymbol(New);
return New;
}
DefinedAbsolute *SymbolTable::addAbsolute(StringRef Name, uint64_t VA) {
auto *New = make<DefinedAbsolute>(Name, VA);
addSymbol(New);
return New;
SymbolBody *SymbolTable::addUndefined(StringRef Name) {
return addUndefined(Name, nullptr, false)->body();
}
void SymbolTable::printMap(llvm::raw_ostream &OS) {
@@ -329,59 +406,19 @@ void SymbolTable::printMap(llvm::raw_ostream &OS) {
}
}
void SymbolTable::addCombinedLTOObject(ObjectFile *Obj) {
for (SymbolBody *Body : Obj->getSymbols()) {
if (!Body->isExternal())
continue;
// We should not see any new undefined symbols at this point, but we'll
// diagnose them later in reportRemainingUndefines().
StringRef Name = Body->getName();
Symbol *Sym = insert(Body);
SymbolBody *Existing = Sym->Body;
if (Existing == Body)
continue;
if (isa<DefinedBitcode>(Existing)) {
Sym->Body = Body;
continue;
}
if (isa<Undefined>(Body)) {
if (auto *L = dyn_cast<Lazy>(Existing)) {
// We may see new references to runtime library symbols such as __chkstk
// here. These symbols must be wholly defined in non-bitcode files.
addMemberFile(L);
continue;
}
}
int Comp = Existing->compare(Body);
if (Comp == 0)
fatal("LTO: unexpected duplicate symbol: " + Name);
if (Comp < 0)
Sym->Body = Body;
}
}
void SymbolTable::addCombinedLTOObjects() {
if (BitcodeFiles.empty())
return;
// Diagnose any undefined symbols early, but do not resolve weak externals,
// as resolution breaks the invariant that each Symbol points to a unique
// SymbolBody, which we rely on to replace DefinedBitcode symbols correctly.
reportRemainingUndefines(/*Resolve=*/false);
// Create an object file and add it to the symbol table by replacing any
// DefinedBitcode symbols with the definitions in the object file.
LTOCodeGenerator CG(BitcodeFile::Context);
CG.setOptLevel(Config->LTOOptLevel);
std::vector<ObjectFile *> Objs = createLTOObjects(&CG);
for (ObjectFile *Obj : Objs)
addCombinedLTOObject(Obj);
size_t NumBitcodeFiles = BitcodeFiles.size();
for (ObjectFile *Obj : Objs)
Obj->parse();
run();
if (BitcodeFiles.size() != NumBitcodeFiles)
fatal("LTO: late loaded symbol created new bitcode reference");
@@ -390,25 +427,17 @@ void SymbolTable::addCombinedLTOObjects() {
// Combine and compile bitcode files and then return the result
// as a vector of regular COFF object files.
std::vector<ObjectFile *> SymbolTable::createLTOObjects(LTOCodeGenerator *CG) {
// All symbols referenced by non-bitcode objects must be preserved.
for (ObjectFile *File : ObjectFiles)
for (SymbolBody *Body : File->getSymbols())
if (auto *S = dyn_cast<DefinedBitcode>(Body->repl()))
CG->addMustPreserveSymbol(S->getName());
// Likewise for bitcode symbols which we initially resolved to non-bitcode.
// All symbols referenced by non-bitcode objects, including GC roots, must be
// preserved. We must also replace bitcode symbols with undefined symbols so
// that they may be replaced with real definitions without conflicting.
for (BitcodeFile *File : BitcodeFiles)
for (SymbolBody *Body : File->getSymbols())
if (isa<DefinedBitcode>(Body) && !isa<DefinedBitcode>(Body->repl()))
for (SymbolBody *Body : File->getSymbols()) {
if (!isa<DefinedBitcode>(Body))
continue;
if (Body->symbol()->IsUsedInRegularObj)
CG->addMustPreserveSymbol(Body->getName());
// Likewise for other symbols that must be preserved.
for (Undefined *U : Config->GCRoot) {
if (auto *S = dyn_cast<DefinedBitcode>(U->repl()))
CG->addMustPreserveSymbol(S->getName());
else if (auto *S = dyn_cast_or_null<DefinedBitcode>(U->getWeakAlias()))
CG->addMustPreserveSymbol(S->getName());
}
replaceBody<Undefined>(Body->symbol(), Body->getName());
}
CG->setModule(BitcodeFiles[0]->takeModule());
for (unsigned I = 1, E = BitcodeFiles.size(); I != E; ++I)
@@ -438,7 +467,6 @@ std::vector<ObjectFile *> SymbolTable::createLTOObjects(LTOCodeGenerator *CG) {
auto *ObjFile = new ObjectFile(MemoryBufferRef(Obj, "<LTO object>"));
Files.emplace_back(ObjFile);
ObjectFiles.push_back(ObjFile);
ObjFile->parse();
ObjFiles.push_back(ObjFile);
}

48
lld/COFF/SymbolTable.h
View File

@@ -22,6 +22,7 @@
#endif
#include <future>
#include <list>
namespace llvm {
struct LTOCodeGenerator;
@@ -31,6 +32,7 @@ namespace lld {
namespace coff {
class Chunk;
class CommonChunk;
class Defined;
class DefinedAbsolute;
class DefinedRelative;
@@ -48,7 +50,9 @@ struct Symbol;
// conflicts. For example, obviously, a defined symbol is better than
// an undefined symbol. Or, if there's a conflict between a lazy and a
// undefined, it'll read an archive member to read a real definition
// to replace the lazy symbol. The logic is implemented in resolve().
// to replace the lazy symbol. The logic is implemented in the
// add*() functions, which are called by input files as they are parsed.
// There is one add* function per symbol type.
class SymbolTable {
public:
void addFile(InputFile *File);
@@ -57,9 +61,10 @@ public:
void run();
bool queueEmpty();
// Print an error message on undefined symbols. If Resolve is true, try to
// resolve any undefined symbols and update the symbol table accordingly.
void reportRemainingUndefines(bool Resolve);
// Try to resolve any undefined symbols and update the symbol table
// accordingly, then print an error message for any remaining undefined
// symbols.
void reportRemainingUndefines();
// Returns a list of chunks of selected symbols.
std::vector<Chunk *> getChunks();
@@ -72,7 +77,7 @@ public:
// mangled symbol. This function tries to find a mangled name
// for U from the symbol table, and if found, set the symbol as
// a weak alias for U.
void mangleMaybe(Undefined *U);
void mangleMaybe(SymbolBody *B);
StringRef findMangle(StringRef Name);
// Print a layout map to OS.
@@ -91,36 +96,49 @@ public:
std::vector<ObjectFile *> ObjectFiles;
// Creates an Undefined symbol for a given name.
Undefined *addUndefined(StringRef Name);
DefinedRelative *addRelative(StringRef Name, uint64_t VA);
DefinedAbsolute *addAbsolute(StringRef Name, uint64_t VA);
SymbolBody *addUndefined(StringRef Name);
Symbol *addRelative(StringRef N, uint64_t VA);
Symbol *addAbsolute(StringRef N, uint64_t VA);
Symbol *addUndefined(StringRef Name, InputFile *F, bool IsWeakAlias);
void addLazy(ArchiveFile *F, const Archive::Symbol Sym);
Symbol *addAbsolute(StringRef N, COFFSymbolRef S);
Symbol *addRegular(ObjectFile *F, COFFSymbolRef S, SectionChunk *C);
Symbol *addBitcode(BitcodeFile *F, StringRef N, bool IsReplaceable);
Symbol *addCommon(ObjectFile *F, COFFSymbolRef S, CommonChunk *C);
Symbol *addImportData(StringRef N, ImportFile *F);
Symbol *addImportThunk(StringRef Name, DefinedImportData *S,
uint16_t Machine);
void reportDuplicate(Symbol *Existing, InputFile *NewFile);
// A list of chunks which to be added to .rdata.
std::vector<Chunk *> LocalImportChunks;
private:
void readArchives();
void readArchive();
void readObjects();
void addSymbol(SymbolBody *New);
void addLazy(Lazy *New, std::vector<Symbol *> *Accum);
Symbol *insert(SymbolBody *New);
std::pair<Symbol *, bool> insert(StringRef Name);
StringRef findByPrefix(StringRef Prefix);
void addMemberFile(Lazy *Body);
void addMemberFile(ArchiveFile *F, const Archive::Symbol Sym);
void addCombinedLTOObject(ObjectFile *Obj);
std::vector<ObjectFile *> createLTOObjects(llvm::LTOCodeGenerator *CG);
llvm::DenseMap<StringRef, Symbol *> Symtab;
std::vector<InputFile *> Files;
std::vector<std::future<ArchiveFile *>> ArchiveQueue;
std::vector<std::future<InputFile *>> ObjectQueue;
std::list<ArchiveFile *> ArchiveQueue;
std::vector<InputFile *> ObjectQueue;
std::vector<BitcodeFile *> BitcodeFiles;
std::vector<SmallString<0>> Objs;
};
extern SymbolTable *Symtab;
} // namespace coff
} // namespace lld

142
lld/COFF/Symbols.cpp
View File

@@ -18,8 +18,6 @@
using namespace llvm;
using namespace llvm::object;
using llvm::sys::fs::identify_magic;
using llvm::sys::fs::file_magic;
namespace lld {
namespace coff {
@@ -49,120 +47,6 @@ InputFile *SymbolBody::getFile() {
return nullptr;
}
// Returns 1, 0 or -1 if this symbol should take precedence
// over the Other, tie or lose, respectively.
int SymbolBody::compare(SymbolBody *Other) {
Kind LK = kind(), RK = Other->kind();
// Normalize so that the smaller kind is on the left.
if (LK > RK)
return -Other->compare(this);
// First handle comparisons between two different kinds.
if (LK != RK) {
if (RK > LastDefinedKind) {
if (LK == LazyKind && cast<Undefined>(Other)->WeakAlias)
return -1;
// The LHS is either defined or lazy and so it wins.
assert((LK <= LastDefinedKind || LK == LazyKind) && "Bad kind!");
return 1;
}
// Bitcode has special complexities.
if (RK == DefinedBitcodeKind) {
auto *RHS = cast<DefinedBitcode>(Other);
switch (LK) {
case DefinedCommonKind:
return 1;
case DefinedRegularKind:
// As an approximation, regular symbols win over bitcode symbols,
// but we definitely have a conflict if the regular symbol is not
// replaceable and neither is the bitcode symbol. We do not
// replicate the rest of the symbol resolution logic here; symbol
// resolution will be done accurately after lowering bitcode symbols
// to regular symbols in addCombinedLTOObject().
if (cast<DefinedRegular>(this)->isCOMDAT() || RHS->IsReplaceable)
return 1;
// Fallthrough to the default of a tie otherwise.
default:
return 0;
}
}
// Either of the object file kind will trump a higher kind.
if (LK <= LastDefinedCOFFKind)
return 1;
// The remaining kind pairs are ties amongst defined symbols.
return 0;
}
// Now handle the case where the kinds are the same.
switch (LK) {
case DefinedRegularKind: {
auto *LHS = cast<DefinedRegular>(this);
auto *RHS = cast<DefinedRegular>(Other);
if (LHS->isCOMDAT() && RHS->isCOMDAT())
return LHS->getFileIndex() < RHS->getFileIndex() ? 1 : -1;
return 0;
}
case DefinedCommonKind: {
auto *LHS = cast<DefinedCommon>(this);
auto *RHS = cast<DefinedCommon>(Other);
if (LHS->getSize() == RHS->getSize())
return LHS->getFileIndex() < RHS->getFileIndex() ? 1 : -1;
return LHS->getSize() > RHS->getSize() ? 1 : -1;
}
case DefinedBitcodeKind: {
auto *LHS = cast<DefinedBitcode>(this);
auto *RHS = cast<DefinedBitcode>(Other);
// If both are non-replaceable, we have a tie.
if (!LHS->IsReplaceable && !RHS->IsReplaceable)
return 0;
// Non-replaceable symbols win, but even two replaceable symboles don't
// tie. If both symbols are replaceable, choice is arbitrary.
if (RHS->IsReplaceable && LHS->IsReplaceable)
return uintptr_t(LHS) < uintptr_t(RHS) ? 1 : -1;
return LHS->IsReplaceable ? -1 : 1;
}
case LazyKind: {
// Don't tie, pick the earliest.
auto *LHS = cast<Lazy>(this);
auto *RHS = cast<Lazy>(Other);
return LHS->getFileIndex() < RHS->getFileIndex() ? 1 : -1;
}
case UndefinedKind: {
auto *LHS = cast<Undefined>(this);
auto *RHS = cast<Undefined>(Other);
// Tie if both undefined symbols have different weak aliases.
if (LHS->WeakAlias && RHS->WeakAlias) {
if (LHS->WeakAlias->getName() != RHS->WeakAlias->getName())
return 0;
return uintptr_t(LHS) < uintptr_t(RHS) ? 1 : -1;
}
return LHS->WeakAlias ? 1 : -1;
}
case DefinedLocalImportKind:
case DefinedImportThunkKind:
case DefinedImportDataKind:
case DefinedAbsoluteKind:
case DefinedRelativeKind:
// These all simply tie.
return 0;
}
llvm_unreachable("unknown symbol kind");
}
COFFSymbolRef DefinedCOFF::getCOFFSymbol() {
size_t SymSize = File->getCOFFObj()->getSymbolTableEntrySize();
if (SymSize == sizeof(coff_symbol16))
@@ -182,34 +66,10 @@ DefinedImportThunk::DefinedImportThunk(StringRef Name, DefinedImportData *S,
}
}
InputFile *Lazy::getMember() {
MemoryBufferRef MBRef = File->getMember(&Sym);
// getMember returns an empty buffer if the member was already
// read from the library.
if (MBRef.getBuffer().empty())
return nullptr;
file_magic Magic = identify_magic(MBRef.getBuffer());
if (Magic == file_magic::coff_import_library)
return make<ImportFile>(MBRef);
InputFile *Obj;
if (Magic == file_magic::coff_object)
Obj = make<ObjectFile>(MBRef);
else if (Magic == file_magic::bitcode)
Obj = make<BitcodeFile>(MBRef);
else
fatal("unknown file type: " + File->getName());
Obj->ParentName = File->getName();
return Obj;
}
Defined *Undefined::getWeakAlias() {
// A weak alias may be a weak alias to another symbol, so check recursively.
for (SymbolBody *A = WeakAlias; A; A = cast<Undefined>(A)->WeakAlias)
if (auto *D = dyn_cast<Defined>(A->repl()))
if (auto *D = dyn_cast<Defined>(A))
return D;
return nullptr;
}

114
lld/COFF/Symbols.h
View File

@@ -32,15 +32,8 @@ class ArchiveFile;
class BitcodeFile;
class InputFile;
class ObjectFile;
class SymbolBody;
// A real symbol object, SymbolBody, is usually accessed indirectly
// through a Symbol. There's always one Symbol for each symbol name.
// The resolver updates SymbolBody pointers as it resolves symbols.
struct Symbol {
explicit Symbol(SymbolBody *P) : Body(P) {}
SymbolBody *Body;
};
struct Symbol;
class SymbolTable;
// The base class for real symbol classes.
class SymbolBody {
@@ -78,21 +71,13 @@ public:
// Returns the file from which this symbol was created.
InputFile *getFile();
// A SymbolBody has a backreference to a Symbol. Originally they are
// doubly-linked. A backreference will never change. But the pointer
// in the Symbol may be mutated by the resolver. If you have a
// pointer P to a SymbolBody and are not sure whether the resolver
// has chosen the object among other objects having the same name,
// you can access P->Backref->Body to get the resolver's result.
void setBackref(Symbol *P) { Backref = P; }
SymbolBody *repl() { return Backref ? Backref->Body : this; }
// Decides which symbol should "win" in the symbol table, this or
// the Other. Returns 1 if this wins, -1 if the Other wins, or 0 if
// they are duplicate (conflicting) symbols.
int compare(SymbolBody *Other);
Symbol *symbol();
const Symbol *symbol() const {
return const_cast<SymbolBody *>(this)->symbol();
}
protected:
friend SymbolTable;
explicit SymbolBody(Kind K, StringRef N = "")
: SymbolKind(K), IsExternal(true), IsCOMDAT(false),
IsReplaceable(false), Name(N) {}
@@ -107,7 +92,6 @@ protected:
unsigned IsReplaceable : 1;
StringRef Name;
Symbol *Backref = nullptr;
};
// The base class for any defined symbols, including absolute symbols,
@@ -149,7 +133,6 @@ public:
}
ObjectFile *getFile() { return File; }
int getFileIndex() { return File->Index; }
COFFSymbolRef getCOFFSymbol();
@@ -195,7 +178,7 @@ public:
uint64_t getRVA() { return Data->getRVA(); }
private:
friend SymbolBody;
friend SymbolTable;
uint64_t getSize() { return Sym->Value; }
CommonChunk *Data;
};
@@ -254,14 +237,11 @@ public:
static bool classof(const SymbolBody *S) { return S->kind() == LazyKind; }
// Returns an object file for this symbol, or a nullptr if the file
// was already returned.
InputFile *getMember();
int getFileIndex() { return File->Index; }
ArchiveFile *File;
private:
friend SymbolTable;
private:
const Archive::Symbol Sym;
};
@@ -295,26 +275,22 @@ public:
// table in an output. The former has "__imp_" prefix.
class DefinedImportData : public Defined {
public:
DefinedImportData(StringRef D, StringRef N, StringRef E,
const coff_import_header *H)
: Defined(DefinedImportDataKind, N), DLLName(D), ExternalName(E), Hdr(H) {
DefinedImportData(StringRef N, ImportFile *F)
: Defined(DefinedImportDataKind, N), File(F) {
}
static bool classof(const SymbolBody *S) {
return S->kind() == DefinedImportDataKind;
}
uint64_t getRVA() { return Location->getRVA(); }
StringRef getDLLName() { return DLLName; }
StringRef getExternalName() { return ExternalName; }
void setLocation(Chunk *AddressTable) { Location = AddressTable; }
uint16_t getOrdinal() { return Hdr->OrdinalHint; }
uint64_t getRVA() { return File->Location->getRVA(); }
StringRef getDLLName() { return File->DLLName; }
StringRef getExternalName() { return File->ExternalName; }
void setLocation(Chunk *AddressTable) { File->Location = AddressTable; }
uint16_t getOrdinal() { return File->Hdr->OrdinalHint; }
private:
StringRef DLLName;
StringRef ExternalName;
const coff_import_header *Hdr;
Chunk *Location = nullptr;
ImportFile *File;
};
// This class represents a symbol for a jump table entry which jumps
@@ -345,17 +321,17 @@ private:
class DefinedLocalImport : public Defined {
public:
DefinedLocalImport(StringRef N, Defined *S)
: Defined(DefinedLocalImportKind, N), Data(S) {}
: Defined(DefinedLocalImportKind, N), Data(new LocalImportChunk(S)) {}
static bool classof(const SymbolBody *S) {
return S->kind() == DefinedLocalImportKind;
}
uint64_t getRVA() { return Data.getRVA(); }
Chunk *getChunk() { return &Data; }
uint64_t getRVA() { return Data->getRVA(); }
Chunk *getChunk() { return Data.get(); }
private:
LocalImportChunk Data;
std::unique_ptr<LocalImportChunk> Data;
};
class DefinedBitcode : public Defined {
@@ -363,6 +339,11 @@ class DefinedBitcode : public Defined {
public:
DefinedBitcode(BitcodeFile *F, StringRef N, bool IsReplaceable)
: Defined(DefinedBitcodeKind, N), File(F) {
// IsReplaceable tracks whether the bitcode symbol may be replaced with some
// other (defined, common or bitcode) symbol. This is the case for common,
// comdat and weak external symbols. We try to replace bitcode symbols with
// "real" symbols (see SymbolTable::add{Regular,Bitcode}), and resolve the
// result against the real symbol from the combined LTO object.
this->IsReplaceable = IsReplaceable;
}
@@ -398,6 +379,45 @@ inline uint64_t Defined::getRVA() {
llvm_unreachable("unknown symbol kind");
}
// A real symbol object, SymbolBody, is usually stored within a Symbol. There's
// always one Symbol for each symbol name. The resolver updates the SymbolBody
// stored in the Body field of this object as it resolves symbols. Symbol also
// holds computed properties of symbol names.
struct Symbol {
// True if this symbol was referenced by a regular (non-bitcode) object.
unsigned IsUsedInRegularObj : 1;
// This field is used to store the Symbol's SymbolBody. This instantiation of
// AlignedCharArrayUnion gives us a struct with a char array field that is
// large and aligned enough to store any derived class of SymbolBody.
llvm::AlignedCharArrayUnion<DefinedRegular, DefinedCommon, DefinedAbsolute,
DefinedRelative, Lazy, Undefined,
DefinedImportData, DefinedImportThunk,
DefinedLocalImport, DefinedBitcode>
Body;
SymbolBody *body() {
return reinterpret_cast<SymbolBody *>(Body.buffer);
}
const SymbolBody *body() const { return const_cast<Symbol *>(this)->body(); }
};
template <typename T, typename... ArgT>
void replaceBody(Symbol *S, ArgT &&... Arg) {
static_assert(sizeof(T) <= sizeof(S->Body), "Body too small");
static_assert(alignof(T) <= alignof(decltype(S->Body)),
"Body not aligned enough");
assert(static_cast<SymbolBody *>(static_cast<T *>(nullptr)) == nullptr &&
"Not a SymbolBody");
new (S->Body.buffer) T(std::forward<ArgT>(Arg)...);
}
inline Symbol *SymbolBody::symbol() {
assert(isExternal());
return reinterpret_cast<Symbol *>(reinterpret_cast<char *>(this) -
offsetof(Symbol, Body));
}
std::string toString(SymbolBody &B);
} // namespace coff

32
lld/COFF/Writer.cpp
View File

@@ -388,7 +388,7 @@ void Writer::createMiscChunks() {
if (!File->SEHCompat)
return;
for (SymbolBody *B : File->SEHandlers)
Handlers.insert(cast<Defined>(B->repl()));
Handlers.insert(cast<Defined>(B));
}
SEHTable.reset(new SEHTableChunk(Handlers));
@@ -428,7 +428,7 @@ void Writer::createImportTables() {
Sec->addChunk(C);
}
if (!DelayIdata.empty()) {
Defined *Helper = cast<Defined>(Config->DelayLoadHelper->repl());
Defined *Helper = cast<Defined>(Config->DelayLoadHelper);
DelayIdata.create(Helper);
OutputSection *Sec = createSection(".didat");
for (Chunk *C : DelayIdata.getChunks())
@@ -471,6 +471,10 @@ size_t Writer::addEntryToStringTable(StringRef Str) {
}
Optional<coff_symbol16> Writer::createSymbol(Defined *Def) {
// Relative symbols are unrepresentable in a COFF symbol table.
if (isa<DefinedRelative>(Def))
return None;
if (auto *D = dyn_cast<DefinedRegular>(Def))
if (!D->getChunk()->isLive())
return None;
@@ -497,7 +501,6 @@ Optional<coff_symbol16> Writer::createSymbol(Defined *Def) {
switch (Def->kind()) {
case SymbolBody::DefinedAbsoluteKind:
case SymbolBody::DefinedRelativeKind:
Sym.Value = Def->getRVA();
Sym.SectionNumber = IMAGE_SYM_ABSOLUTE;
break;
@@ -530,16 +533,13 @@ void Writer::createSymbolAndStringTable() {
Sec->setStringTableOff(addEntryToStringTable(Name));
}
std::set<SymbolBody *> SeenSymbols;
for (lld::coff::ObjectFile *File : Symtab->ObjectFiles)
for (SymbolBody *B : File->getSymbols())
if (auto *D = dyn_cast<Defined>(B))
if (Optional<coff_symbol16> Sym = createSymbol(D))
OutputSymtab.push_back(*Sym);
for (ImportFile *File : Symtab->ImportFiles)
for (SymbolBody *B : File->getSymbols())
if (Optional<coff_symbol16> Sym = createSymbol(cast<Defined>(B)))
OutputSymtab.push_back(*Sym);
if (SeenSymbols.insert(D).second)
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.
@@ -630,7 +630,7 @@ template <typename PEHeaderTy> void Writer::writeHeader() {
PE->SizeOfImage = SizeOfImage;
PE->SizeOfHeaders = SizeOfHeaders;
if (!Config->NoEntry) {
Defined *Entry = cast<Defined>(Config->Entry->repl());
Defined *Entry = cast<Defined>(Config->Entry);
PE->AddressOfEntryPoint = Entry->getRVA();
// Pointer to thumb code must have the LSB set, so adjust it.
if (Config->Machine == ARMNT)
@@ -685,7 +685,7 @@ template <typename PEHeaderTy> void Writer::writeHeader() {
Dir[BASE_RELOCATION_TABLE].Size = Sec->getVirtualSize();
}
if (Symbol *Sym = Symtab->findUnderscore("_tls_used")) {
if (Defined *B = dyn_cast<Defined>(Sym->Body)) {
if (Defined *B = dyn_cast<Defined>(Sym->body())) {
Dir[TLS_TABLE].RelativeVirtualAddress = B->getRVA();
Dir[TLS_TABLE].Size = Config->is64()
? sizeof(object::coff_tls_directory64)
@@ -697,7 +697,7 @@ template <typename PEHeaderTy> void Writer::writeHeader() {
Dir[DEBUG_DIRECTORY].Size = DebugDirectory->getSize();
}
if (Symbol *Sym = Symtab->findUnderscore("_load_config_used")) {
if (auto *B = dyn_cast<DefinedRegular>(Sym->Body)) {
if (auto *B = dyn_cast<DefinedRegular>(Sym->body())) {
SectionChunk *SC = B->getChunk();
assert(B->getRVA() >= SC->getRVA());
uint64_t OffsetInChunk = B->getRVA() - SC->getRVA();
@@ -754,8 +754,10 @@ void Writer::openFile(StringRef Path) {
void Writer::fixSafeSEHSymbols() {
if (!SEHTable)
return;
Config->SEHTable->setRVA(SEHTable->getRVA());
Config->SEHCount->setVA(SEHTable->getSize() / 4);
if (auto *T = dyn_cast<DefinedRelative>(Config->SEHTable->body()))
T->setRVA(SEHTable->getRVA());
if (auto *C = dyn_cast<DefinedAbsolute>(Config->SEHCount->body()))
C->setVA(SEHTable->getSize() / 4);
}
// Handles /section options to allow users to overwrite

2
lld/test/COFF/include2.test
View File

@@ -9,6 +9,6 @@
CHECK: include2.test.tmp1.obj
CHECK: include2.test.tmp2.lib
CHECK: include2.test.tmp3.lib
CHECK: include2.test.tmp2.lib(include2.test.tmp2.obj) for foo
CHECK: include2.test.tmp3.lib
CHECK: include2.test.tmp3.lib(include2.test.tmp3.obj) for bar

2
lld/test/COFF/order.test
View File

@@ -11,5 +11,5 @@
CHECK: order.test.tmp1.obj
CHECK: order.test.tmp3.obj
CHECK: order.test.tmp2.lib
CHECK: order.test.tmp3.lib
CHECK: order.test.tmp2.lib(order.test.tmp2.obj) for foo
CHECK: order.test.tmp3.lib

54
lld/test/COFF/symtab.test
View File

@@ -36,6 +36,24 @@
# CHECK-NEXT: AuxSymbolCount: 0
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: MessageBoxA
# CHECK-NEXT: Value: 80
# CHECK-NEXT: Section: .text (2)
# CHECK-NEXT: BaseType: Null (0x0)
# CHECK-NEXT: ComplexType: Null (0x0)
# CHECK-NEXT: StorageClass: External (0x2)
# CHECK-NEXT: AuxSymbolCount: 0
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: ExitProcess
# CHECK-NEXT: Value: 64
# CHECK-NEXT: Section: .text (2)
# CHECK-NEXT: BaseType: Null (0x0)
# CHECK-NEXT: ComplexType: Null (0x0)
# CHECK-NEXT: StorageClass: External (0x2)
# CHECK-NEXT: AuxSymbolCount: 0
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: message
# CHECK-NEXT: Value: 6
# CHECK-NEXT: Section: .text2 (3)
@@ -71,42 +89,6 @@
# CHECK-NEXT: StorageClass: External (0x2)
# CHECK-NEXT: AuxSymbolCount: 0
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: __imp_ExitProcess
# CHECK-NEXT: Value: 64
# CHECK-NEXT: Section: .idata (5)
# CHECK-NEXT: BaseType: Null (0x0)
# CHECK-NEXT: ComplexType: Null (0x0)
# CHECK-NEXT: StorageClass: External (0x2)
# CHECK-NEXT: AuxSymbolCount: 0
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: ExitProcess
# CHECK-NEXT: Value: 64
# CHECK-NEXT: Section: .text (2)
# CHECK-NEXT: BaseType: Null (0x0)
# CHECK-NEXT: ComplexType: Null (0x0)
# CHECK-NEXT: StorageClass: External (0x2)
# CHECK-NEXT: AuxSymbolCount: 0
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: __imp_MessageBoxA
# CHECK-NEXT: Value: 72
# CHECK-NEXT: Section: .idata (5)
# CHECK-NEXT: BaseType: Null (0x0)
# CHECK-NEXT: ComplexType: Null (0x0)
# CHECK-NEXT: StorageClass: External (0x2)
# CHECK-NEXT: AuxSymbolCount: 0
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: MessageBoxA
# CHECK-NEXT: Value: 80
# CHECK-NEXT: Section: .text (2)
# CHECK-NEXT: BaseType: Null (0x0)
# CHECK-NEXT: ComplexType: Null (0x0)
# CHECK-NEXT: StorageClass: External (0x2)
# CHECK-NEXT: AuxSymbolCount: 0
# CHECK-NEXT: }
# CHECK-NEXT: ]
# NO: Symbols [