[lld] 4c79e1a - [lld-macho] Implement -load_hidden
Daniel Bertalan via llvm-commits
llvm-commits at lists.llvm.org
Mon Jul 25 11:59:51 PDT 2022
Author: Daniel Bertalan
Date: 2022-07-25T20:59:33+02:00
New Revision: 4c79e1a3f4eb790f40239833ae237e828ce07386
URL: https://github.com/llvm/llvm-project/commit/4c79e1a3f4eb790f40239833ae237e828ce07386
DIFF: https://github.com/llvm/llvm-project/commit/4c79e1a3f4eb790f40239833ae237e828ce07386.diff
LOG: [lld-macho] Implement -load_hidden
This flag was introduced in ld64-609. It instructs the linker to link to
a static library while treating its symbols as if they had hidden
visibility. This is useful when building a dylib that links to static
libraries but we don't want the symbols from those to be exported.
Closes #51505
Differential Revision: https://reviews.llvm.org/D130473
Added:
lld/test/MachO/load-hidden.s
Modified:
lld/MachO/Driver.cpp
lld/MachO/DriverUtils.cpp
lld/MachO/InputFiles.cpp
lld/MachO/InputFiles.h
lld/MachO/Options.td
lld/test/MachO/reroot-path.s
Removed:
################################################################################
diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
index 454708fad4ef2..c6445438dfeb3 100644
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -266,7 +266,8 @@ static DenseMap<StringRef, ArchiveFileInfo> loadedArchives;
static InputFile *addFile(StringRef path, LoadType loadType,
bool isLazy = false, bool isExplicit = true,
- bool isBundleLoader = false) {
+ bool isBundleLoader = false,
+ bool isForceHidden = false) {
Optional<MemoryBufferRef> buffer = readFile(path);
if (!buffer)
return nullptr;
@@ -293,7 +294,7 @@ static InputFile *addFile(StringRef path, LoadType loadType,
if (!archive->isEmpty() && !archive->hasSymbolTable())
error(path + ": archive has no index; run ranlib to add one");
- file = make<ArchiveFile>(std::move(archive));
+ file = make<ArchiveFile>(std::move(archive), isForceHidden);
} else {
file = entry->second.file;
// Command-line loads take precedence. If file is previously loaded via
@@ -1035,6 +1036,11 @@ static void createFiles(const InputArgList &args) {
case OPT_force_load:
addFile(rerootPath(arg->getValue()), LoadType::CommandLineForce);
break;
+ case OPT_load_hidden:
+ addFile(rerootPath(arg->getValue()), LoadType::CommandLine,
+ /*isLazy=*/false, /*isExplicit=*/true, /*isBundleLoader=*/false,
+ /*isForceHidden=*/true);
+ break;
case OPT_l:
case OPT_needed_l:
case OPT_reexport_l:
diff --git a/lld/MachO/DriverUtils.cpp b/lld/MachO/DriverUtils.cpp
index b52d5e851c62d..d8e474d15cfd3 100644
--- a/lld/MachO/DriverUtils.cpp
+++ b/lld/MachO/DriverUtils.cpp
@@ -150,6 +150,7 @@ std::string macho::createResponseFile(const InputArgList &args) {
break;
case OPT_force_load:
case OPT_weak_library:
+ case OPT_load_hidden:
os << arg->getSpelling() << " "
<< quote(rewriteInputPath(arg->getValue())) << "\n";
break;
diff --git a/lld/MachO/InputFiles.cpp b/lld/MachO/InputFiles.cpp
index e3bf553e53347..0a5a37d9f78a9 100644
--- a/lld/MachO/InputFiles.cpp
+++ b/lld/MachO/InputFiles.cpp
@@ -768,7 +768,7 @@ void ObjFile::parseRelocations(ArrayRef<SectionHeader> sectionHeaders,
template <class NList>
static macho::Symbol *createDefined(const NList &sym, StringRef name,
InputSection *isec, uint64_t value,
- uint64_t size) {
+ uint64_t size, bool forceHidden) {
// Symbol scope is determined by sym.n_type & (N_EXT | N_PEXT):
// N_EXT: Global symbols. These go in the symbol table during the link,
// and also in the export table of the output so that the dynamic
@@ -787,7 +787,10 @@ static macho::Symbol *createDefined(const NList &sym, StringRef name,
(sym.n_desc & (N_WEAK_DEF | N_WEAK_REF)) == (N_WEAK_DEF | N_WEAK_REF);
if (sym.n_type & N_EXT) {
- bool isPrivateExtern = sym.n_type & N_PEXT;
+ // -load_hidden makes us treat global symbols as linkage unit scoped.
+ // Duplicates are reported but the symbol does not go in the export trie.
+ bool isPrivateExtern = sym.n_type & N_PEXT || forceHidden;
+
// lld's behavior for merging symbols is slightly
diff erent from ld64:
// ld64 picks the winning symbol based on several criteria (see
// pickBetweenRegularAtoms() in ld64's SymbolTable.cpp), while lld
@@ -844,11 +847,12 @@ static macho::Symbol *createDefined(const NList &sym, StringRef name,
// InputSection. They cannot be weak.
template <class NList>
static macho::Symbol *createAbsolute(const NList &sym, InputFile *file,
- StringRef name) {
+ StringRef name, bool forceHidden) {
if (sym.n_type & N_EXT) {
+ bool isPrivateExtern = sym.n_type & N_PEXT || forceHidden;
return symtab->addDefined(
name, file, nullptr, sym.n_value, /*size=*/0,
- /*isWeakDef=*/false, sym.n_type & N_PEXT, sym.n_desc & N_ARM_THUMB_DEF,
+ /*isWeakDef=*/false, isPrivateExtern, sym.n_desc & N_ARM_THUMB_DEF,
/*isReferencedDynamically=*/false, sym.n_desc & N_NO_DEAD_STRIP,
/*isWeakDefCanBeHidden=*/false);
}
@@ -864,15 +868,16 @@ template <class NList>
macho::Symbol *ObjFile::parseNonSectionSymbol(const NList &sym,
StringRef name) {
uint8_t type = sym.n_type & N_TYPE;
+ bool isPrivateExtern = sym.n_type & N_PEXT || forceHidden;
switch (type) {
case N_UNDF:
return sym.n_value == 0
? symtab->addUndefined(name, this, sym.n_desc & N_WEAK_REF)
: symtab->addCommon(name, this, sym.n_value,
1 << GET_COMM_ALIGN(sym.n_desc),
- sym.n_type & N_PEXT);
+ isPrivateExtern);
case N_ABS:
- return createAbsolute(sym, this, name);
+ return createAbsolute(sym, this, name, forceHidden);
case N_PBUD:
case N_INDR:
error("TODO: support symbols of type " + std::to_string(type));
@@ -944,7 +949,8 @@ void ObjFile::parseSymbols(ArrayRef<typename LP::section> sectionHeaders,
" at misaligned offset");
continue;
}
- symbols[symIndex] = createDefined(sym, name, isec, 0, isec->getSize());
+ symbols[symIndex] =
+ createDefined(sym, name, isec, 0, isec->getSize(), forceHidden);
}
continue;
}
@@ -979,8 +985,8 @@ void ObjFile::parseSymbols(ArrayRef<typename LP::section> sectionHeaders,
// 4. If we have a literal section (e.g. __cstring and __literal4).
if (!subsectionsViaSymbols || symbolOffset == 0 ||
sym.n_desc & N_ALT_ENTRY || !isa<ConcatInputSection>(isec)) {
- symbols[symIndex] =
- createDefined(sym, name, isec, symbolOffset, symbolSize);
+ symbols[symIndex] = createDefined(sym, name, isec, symbolOffset,
+ symbolSize, forceHidden);
continue;
}
auto *concatIsec = cast<ConcatInputSection>(isec);
@@ -998,8 +1004,8 @@ void ObjFile::parseSymbols(ArrayRef<typename LP::section> sectionHeaders,
// By construction, the symbol will be at offset zero in the new
// subsection.
- symbols[symIndex] =
- createDefined(sym, name, nextIsec, /*value=*/0, symbolSize);
+ symbols[symIndex] = createDefined(sym, name, nextIsec, /*value=*/0,
+ symbolSize, forceHidden);
// TODO: ld64 appears to preserve the original alignment as well as each
// subsection's offset from the last aligned address. We should consider
// emulating that behavior.
@@ -1036,8 +1042,8 @@ OpaqueFile::OpaqueFile(MemoryBufferRef mb, StringRef segName,
}
ObjFile::ObjFile(MemoryBufferRef mb, uint32_t modTime, StringRef archiveName,
- bool lazy)
- : InputFile(ObjKind, mb, lazy), modTime(modTime) {
+ bool lazy, bool forceHidden)
+ : InputFile(ObjKind, mb, lazy), modTime(modTime), forceHidden(forceHidden) {
this->archiveName = std::string(archiveName);
if (lazy) {
if (target->wordSize == 8)
@@ -2061,26 +2067,27 @@ void DylibFile::checkAppExtensionSafety(bool dylibIsAppExtensionSafe) const {
warn("using '-application_extension' with unsafe dylib: " + toString(this));
}
-ArchiveFile::ArchiveFile(std::unique_ptr<object::Archive> &&f)
- : InputFile(ArchiveKind, f->getMemoryBufferRef()), file(std::move(f)) {}
+ArchiveFile::ArchiveFile(std::unique_ptr<object::Archive> &&f, bool forceHidden)
+ : InputFile(ArchiveKind, f->getMemoryBufferRef()), file(std::move(f)),
+ forceHidden(forceHidden) {}
void ArchiveFile::addLazySymbols() {
for (const object::Archive::Symbol &sym : file->symbols())
symtab->addLazyArchive(sym.getName(), this, sym);
}
-static Expected<InputFile *> loadArchiveMember(MemoryBufferRef mb,
- uint32_t modTime,
- StringRef archiveName,
- uint64_t offsetInArchive) {
+static Expected<InputFile *>
+loadArchiveMember(MemoryBufferRef mb, uint32_t modTime, StringRef archiveName,
+ uint64_t offsetInArchive, bool forceHidden) {
if (config->zeroModTime)
modTime = 0;
switch (identify_magic(mb.getBuffer())) {
case file_magic::macho_object:
- return make<ObjFile>(mb, modTime, archiveName);
+ return make<ObjFile>(mb, modTime, archiveName, /*lazy=*/false, forceHidden);
case file_magic::bitcode:
- return make<BitcodeFile>(mb, archiveName, offsetInArchive);
+ return make<BitcodeFile>(mb, archiveName, offsetInArchive, /*lazy=*/false,
+ forceHidden);
default:
return createStringError(inconvertibleErrorCode(),
mb.getBufferIdentifier() +
@@ -2104,8 +2111,8 @@ Error ArchiveFile::fetch(const object::Archive::Child &c, StringRef reason) {
if (!modTime)
return modTime.takeError();
- Expected<InputFile *> file =
- loadArchiveMember(*mb, toTimeT(*modTime), getName(), c.getChildOffset());
+ Expected<InputFile *> file = loadArchiveMember(
+ *mb, toTimeT(*modTime), getName(), c.getChildOffset(), forceHidden);
if (!file)
return file.takeError();
@@ -2168,8 +2175,8 @@ static macho::Symbol *createBitcodeSymbol(const lto::InputFile::Symbol &objSym,
}
BitcodeFile::BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
- uint64_t offsetInArchive, bool lazy)
- : InputFile(BitcodeKind, mb, lazy) {
+ uint64_t offsetInArchive, bool lazy, bool forceHidden)
+ : InputFile(BitcodeKind, mb, lazy), forceHidden(forceHidden) {
this->archiveName = std::string(archiveName);
std::string path = mb.getBufferIdentifier().str();
// ThinLTO assumes that all MemoryBufferRefs given to it have a unique
diff --git a/lld/MachO/InputFiles.h b/lld/MachO/InputFiles.h
index 5deb05272a6b1..3359161d83341 100644
--- a/lld/MachO/InputFiles.h
+++ b/lld/MachO/InputFiles.h
@@ -156,7 +156,7 @@ struct FDE {
class ObjFile final : public InputFile {
public:
ObjFile(MemoryBufferRef mb, uint32_t modTime, StringRef archiveName,
- bool lazy = false);
+ bool lazy = false, bool forceHidden = false);
ArrayRef<llvm::MachO::data_in_code_entry> getDataInCode() const;
template <class LP> void parse();
@@ -171,6 +171,7 @@ class ObjFile final : public InputFile {
std::unique_ptr<lld::DWARFCache> dwarfCache;
Section *addrSigSection = nullptr;
const uint32_t modTime;
+ bool forceHidden;
std::vector<ConcatInputSection *> debugSections;
std::vector<CallGraphEntry> callGraph;
llvm::DenseMap<ConcatInputSection *, FDE> fdes;
@@ -259,7 +260,8 @@ class DylibFile final : public InputFile {
// .a file
class ArchiveFile final : public InputFile {
public:
- explicit ArchiveFile(std::unique_ptr<llvm::object::Archive> &&file);
+ explicit ArchiveFile(std::unique_ptr<llvm::object::Archive> &&file,
+ bool forceHidden);
void addLazySymbols();
void fetch(const llvm::object::Archive::Symbol &);
// LLD normally doesn't use Error for error-handling, but the underlying
@@ -273,12 +275,15 @@ class ArchiveFile final : public InputFile {
// Keep track of children fetched from the archive by tracking
// which address offsets have been fetched already.
llvm::DenseSet<uint64_t> seen;
+ // Load all symbols with hidden visibility (-load_hidden).
+ bool forceHidden;
};
class BitcodeFile final : public InputFile {
public:
explicit BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
- uint64_t offsetInArchive, bool lazy = false);
+ uint64_t offsetInArchive, bool lazy = false,
+ bool forceHidden = false);
static bool classof(const InputFile *f) { return f->kind() == BitcodeKind; }
void parse();
@@ -286,6 +291,8 @@ class BitcodeFile final : public InputFile {
private:
void parseLazy();
+
+ bool forceHidden;
};
extern llvm::SetVector<InputFile *> inputFiles;
diff --git a/lld/MachO/Options.td b/lld/MachO/Options.td
index b3d74a83f5822..38b79f820f805 100644
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -240,6 +240,10 @@ def force_load : Separate<["-"], "force_load">,
def force_load_swift_libs : Flag<["-"], "force_load_swift_libs">,
HelpText<"Apply -force_load to libraries listed in LC_LINKER_OPTIONS whose names start with 'swift'">,
Group<grp_libs>;
+def load_hidden : Separate<["-"], "load_hidden">,
+ MetaVarName<"<path>">,
+ HelpText<"Load all symbols from static library with hidden visibility">,
+ Group<grp_libs>;
def grp_content : OptionGroup<"content">, HelpText<"ADDITIONAL CONTENT">;
diff --git a/lld/test/MachO/load-hidden.s b/lld/test/MachO/load-hidden.s
new file mode 100644
index 0000000000000..003409c278fa4
--- /dev/null
+++ b/lld/test/MachO/load-hidden.s
@@ -0,0 +1,72 @@
+# REQUIRES: x86
+# RUN: rm -rf %t; split-file %s %t
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/archive-foo.s -o %t/archive-foo.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/archive-baz.s -o %t/archive-baz.o
+# RUN: llvm-ar rcs %t/foo.a %t/archive-foo.o
+# RUN: llvm-ar rcs %t/baz.a %t/archive-baz.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/obj.s -o %t/obj.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/obj-bar.s -o %t/obj-bar.o
+
+# RUN: %lld -dylib -lSystem %t/obj.o -load_hidden %t/foo.a -o %t/test.dylib
+# RUN: llvm-nm %t/test.dylib | FileCheck %s
+# CHECK-DAG: t _foo
+# CHECK-DAG: d _bar
+
+## If an archive has already been loaded without -load_hidden earlier in the command line,
+## -load_hidden does not have an effect.
+# RUN: %lld -dylib -lSystem %t/obj.o %t/foo.a -load_hidden %t/foo.a -o %t/test-regular-then-hidden.dylib
+# RUN: llvm-nm %t/test-regular-then-hidden.dylib | FileCheck %s --check-prefix=REGULAR-THEN-HIDDEN
+# REGULAR-THEN-HIDDEN-DAG: T _foo
+# REGULAR-THEN-HIDDEN-DAG: D _bar
+
+## If -load_hidden comes first, the symbols will have hidden visibility.
+# RUN: %lld -dylib -lSystem %t/obj.o -load_hidden %t/foo.a %t/foo.a -o %t/test-hidden-then-regular.dylib
+# RUN: llvm-nm %t/test-hidden-then-regular.dylib | FileCheck %s --check-prefix=HIDDEN-THEN-REGULAR
+# HIDDEN-THEN-REGULAR-DAG: t _foo
+# HIDDEN-THEN-REGULAR-DAG: d _bar
+
+## If both -load_hidden and -force_load are specified, the earlier one will have an effect.
+# RUN: %lld -dylib -lSystem %t/obj.o %t/foo.a -force_load %t/baz.a -load_hidden %t/baz.a -o %t/test-force-then-hidden.dylib
+# RUN: llvm-nm %t/test-force-then-hidden.dylib | FileCheck %s --check-prefix=FORCE-THEN-HIDDEN
+# FORCE-THEN-HIDDEN: T _baz
+# RUN: %lld -dylib -lSystem %t/obj.o %t/foo.a -load_hidden %t/baz.a -force_load %t/baz.a -o %t/test-hidden-then-force.dylib
+# RUN: llvm-nm %t/test-hidden-then-force.dylib | FileCheck %s --check-prefix=HIDDEN-THEN-FORCE
+# HIDDEN-THEN-FORCE-NOT: _baz
+
+## -load_hidden does not cause the library to be loaded eagerly.
+# RUN: %lld -dylib -lSystem %t/obj.o -load_hidden %t/foo.a -load_hidden %t/baz.a -o %t/test-lazy.dylib
+# RUN: llvm-nm %t/test-lazy.dylib | FileCheck %s --check-prefix=LAZY
+# LAZY-NOT: _baz
+
+## Specifying the same library twice is fine.
+# RUN: %lld -dylib -lSystem %t/obj.o -load_hidden %t/foo.a -load_hidden %t/foo.a -o %t/test-twice.dylib
+# RUN: llvm-nm %t/test-twice.dylib | FileCheck %s --check-prefix=TWICE
+# TWICE-DAG: t _foo
+# TWICE-DAG: d _bar
+
+## -load_hidden causes the symbols to have "private external" visibility, so duplicate definitions
+## are not allowed.
+# RUN: not %lld -dylib -lSystem %t/obj.o %t/obj-bar.o -load_hidden %t/foo.a 2>&1 | FileCheck %s --check-prefix=DUP
+# DUP: error: duplicate symbol: _bar
+
+#--- archive-foo.s
+.globl _foo
+_foo:
+
+.data
+.globl _bar
+_bar:
+
+#--- archive-baz.s
+.globl _baz
+_baz:
+
+#--- obj-bar.s
+.data
+.globl _bar
+_bar:
+
+#--- obj.s
+.globl _test
+_test:
+ call _foo
diff --git a/lld/test/MachO/reroot-path.s b/lld/test/MachO/reroot-path.s
index b99d99176f991..43ff21d1b915f 100644
--- a/lld/test/MachO/reroot-path.s
+++ b/lld/test/MachO/reroot-path.s
@@ -39,6 +39,10 @@
# RUN: tar xf %t/repro4.tar -C %t
# RUN: cd %t/repro4; %no-arg-lld @response.txt | FileCheck %s -DDIR="%:t/%:t"
+# RUN: %lld --reproduce %t/repro7.tar -lSystem -syslibroot %t -force_load %t/foo.a -force_load %t/bar.a %t/test.o -o /dev/null -t | FileCheck %s -DDIR="%t/%:t"
+# RUN: tar xf %t/repro7.tar -C %t
+# RUN: cd %t/repro7; %no-arg-lld @response.txt | FileCheck %s -DDIR="%:t/%:t"
+
# RUN: echo "%t/libfoo.dylib" > %t/filelist
# RUN: echo "%t/libbar.dylib" >> %t/filelist
# RUN: %lld --reproduce %t/repro5.tar -lSystem -syslibroot %t -filelist %t/filelist %t/test.o -o /dev/null -t | FileCheck %s -DDIR="%t/%:t"
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