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[llvm-objcopy] Add support of symbol modification flags for MachO (#120895)
This patch adds support of the following llvm-objcopy flags for MachO: - `--globalize-symbol`, `--globalize-symbols`, - `--keep-global-symbol`, `-G`, `--keep-global-symbols`, - `--localize-symbol`, `-L`, `--localize-symbols`, - `--skip-symbol`, `--skip-symbols`. Code in `updateAndRemoveSymbols` for MachO is kept similar to its version for ELF. Fixes #120894
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‎llvm/docs/CommandGuide/llvm-objcopy.rst

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@@ -78,10 +78,47 @@ multiple file formats.
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Enable deterministic mode when copying archives, i.e. use 0 for archive member
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header UIDs, GIDs and timestamp fields. On by default.
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.. option:: --globalize-symbol <symbol>
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Mark any defined symbols named ``<symbol>`` as global symbols in the output.
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Can be specified multiple times to mark multiple symbols.
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.. option:: --globalize-symbols <filename>
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Read a list of names from the file ``<filename>`` and mark defined symbols with
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those names as global in the output. In the file, each line represents a single
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symbol, with leading and trailing whitespace ignored, as is anything following
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a '#'. Can be specified multiple times to read names from multiple files.
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.. option:: --help, -h
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Print a summary of command line options.
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.. option:: --keep-global-symbol <symbol>, -G
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Mark all symbols local in the output, except for symbols with the name
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``<symbol>``. Can be specified multiple times to ignore multiple symbols.
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.. option:: --keep-global-symbols <filename>
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Mark all symbols local in the output, except for symbols named in the file
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``<filename>``. In the file, each line represents a single symbol, with leading
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and trailing whitespace ignored, as is anything following a '#'. Can be
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specified multiple times to read names from multiple files.
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.. option:: --localize-symbol <symbol>, -L
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Mark any defined non-common symbol named ``<symbol>`` as a local symbol in the
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output. Can be specified multiple times to mark multiple symbols as local.
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.. option:: --localize-symbols <filename>
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Read a list of names from the file ``<filename>`` and mark defined non-common
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symbols with those names as local in the output. In the file, each line
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represents a single symbol, with leading and trailing whitespace ignored, as is
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anything following a '#'. Can be specified multiple times to read names from
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multiple files.
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.. option:: --only-keep-debug
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Produce a debug file as the output that only preserves contents of sections
@@ -177,6 +214,19 @@ multiple file formats.
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flags.
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- `share` = add the `IMAGE_SCN_MEM_SHARED` and `IMAGE_SCN_MEM_READ` flags.
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.. option:: --skip-symbol <symbol>
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Do not change the parameters of symbol ``<symbol>`` when executing other
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options that can change the symbol's name, binding or visibility.
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.. option:: --skip-symbols <filename>
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Do not change the parameters of symbols named in the file ``<filename>`` when
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executing other options that can change the symbol's name, binding or
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visibility. In the file, each line represents a single symbol, with leading
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and trailing whitespace ignored, as is anything following a '#'.
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Can be specified multiple times to read names from multiple files.
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.. option:: --strip-all-gnu
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Remove all symbols, debug sections and relocations from the output. This option
@@ -355,18 +405,6 @@ them.
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For binary outputs, fill the gaps between sections with ``<value>`` instead
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of zero. The value must be an unsigned 8-bit integer.
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.. option:: --globalize-symbol <symbol>
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Mark any defined symbols named ``<symbol>`` as global symbols in the output.
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Can be specified multiple times to mark multiple symbols.
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.. option:: --globalize-symbols <filename>
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Read a list of names from the file ``<filename>`` and mark defined symbols with
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those names as global in the output. In the file, each line represents a single
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symbol, with leading and trailing whitespace ignored, as is anything following
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a '#'. Can be specified multiple times to read names from multiple files.
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.. option:: --input-target <format>, -I
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Read the input as the specified format. See `SUPPORTED FORMATS`_ for a list of
@@ -377,18 +415,6 @@ them.
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Keep symbols of type `STT_FILE`, even if they would otherwise be stripped.
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.. option:: --keep-global-symbol <symbol>, -G
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Mark all symbols local in the output, except for symbols with the name
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``<symbol>``. Can be specified multiple times to ignore multiple symbols.
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.. option:: --keep-global-symbols <filename>
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Mark all symbols local in the output, except for symbols named in the file
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``<filename>``. In the file, each line represents a single symbol, with leading
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and trailing whitespace ignored, as is anything following a '#'. Can be
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specified multiple times to read names from multiple files.
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.. option:: --keep-section <section>
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When removing sections from the output, do not remove sections named
@@ -410,19 +436,6 @@ them.
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Mark all symbols with hidden or internal visibility local in the output.
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.. option:: --localize-symbol <symbol>, -L
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Mark any defined non-common symbol named ``<symbol>`` as a local symbol in the
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output. Can be specified multiple times to mark multiple symbols as local.
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.. option:: --localize-symbols <filename>
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Read a list of names from the file ``<filename>`` and mark defined non-common
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symbols with those names as local in the output. In the file, each line
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represents a single symbol, with leading and trailing whitespace ignored, as is
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anything following a '#'. Can be specified multiple times to read names from
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multiple files.
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.. option:: --new-symbol-visibility <visibility>
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Specify the visibility of the symbols automatically created when using binary
@@ -489,19 +502,6 @@ them.
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Read a list of symbols from <filename> and change their visibility to the
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specified value. Visibility values: default, internal, hidden, protected.
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.. option:: --skip-symbol <symbol>
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Do not change the parameters of symbol ``<symbol>`` when executing other
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options that can change the symbol's name, binding or visibility.
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.. option:: --skip-symbols <filename>
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Do not change the parameters of symbols named in the file ``<filename>`` when
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executing other options that can change the symbol's name, binding or
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visibility. In the file, each line represents a single symbol, with leading
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and trailing whitespace ignored, as is anything following a '#'.
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Can be specified multiple times to read names from multiple files.
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.. option:: --split-dwo <dwo-file>
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Equivalent to running :program:`llvm-objcopy` with :option:`--extract-dwo` and

‎llvm/docs/ReleaseNotes.md

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@@ -350,6 +350,12 @@ Changes to the Debug Info
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Changes to the LLVM tools
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---------------------------------
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* llvm-objcopy now supports the following options for Mach-O:
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`--globalize-symbol`, `--globalize-symbols`,
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`--keep-global-symbol`, `--keep-global-symbols`,
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`--localize-symbol`, `--localize-symbols`,
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`--skip-symbol`, `--skip-symbols`.
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Changes to LLDB
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---------------------------------
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‎llvm/lib/ObjCopy/ConfigManager.cpp

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Original file line numberDiff line numberDiff line change
@@ -36,11 +36,9 @@ Expected<const COFFConfig &> ConfigManager::getCOFFConfig() const {
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Expected<const MachOConfig &> ConfigManager::getMachOConfig() const {
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if (!Common.SplitDWO.empty() || !Common.SymbolsPrefix.empty() ||
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!Common.SymbolsPrefixRemove.empty() || !Common.SymbolsToSkip.empty() ||
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!Common.SymbolsPrefixRemove.empty() ||
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!Common.AllocSectionsPrefix.empty() || !Common.KeepSection.empty() ||
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!Common.SymbolsToGlobalize.empty() || !Common.SymbolsToKeep.empty() ||
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!Common.SymbolsToLocalize.empty() ||
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!Common.SymbolsToKeepGlobal.empty() || !Common.SectionsToRename.empty() ||
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!Common.SymbolsToKeep.empty() || !Common.SectionsToRename.empty() ||
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!Common.UnneededSymbolsToRemove.empty() ||
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!Common.SetSectionAlignment.empty() || !Common.SetSectionFlags.empty() ||
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!Common.SetSectionType.empty() || Common.ExtractDWO ||

‎llvm/lib/ObjCopy/MachO/MachOObjcopy.cpp

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@@ -93,19 +93,38 @@ static void markSymbols(const CommonConfig &, Object &Obj) {
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static void updateAndRemoveSymbols(const CommonConfig &Config,
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const MachOConfig &MachOConfig,
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Object &Obj) {
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for (SymbolEntry &Sym : Obj.SymTable) {
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// Weaken symbols first to match ELFObjcopy behavior.
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bool IsExportedAndDefined =
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(Sym.n_type & llvm::MachO::N_EXT) &&
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(Sym.n_type & llvm::MachO::N_TYPE) != llvm::MachO::N_UNDF;
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if (IsExportedAndDefined &&
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Obj.SymTable.updateSymbols([&](SymbolEntry &Sym) {
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if (Config.SymbolsToSkip.matches(Sym.Name))
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return;
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if (!Sym.isUndefinedSymbol() && Config.SymbolsToLocalize.matches(Sym.Name))
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Sym.n_type &= ~MachO::N_EXT;
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// Note: these two globalize flags have very similar names but different
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// meanings:
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//
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// --globalize-symbol: promote a symbol to global
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// --keep-global-symbol: all symbols except for these should be made local
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//
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// If --globalize-symbol is specified for a given symbol, it will be
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// global in the output file even if it is not included via
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// --keep-global-symbol. Because of that, make sure to check
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// --globalize-symbol second.
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if (!Sym.isUndefinedSymbol() && !Config.SymbolsToKeepGlobal.empty() &&
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!Config.SymbolsToKeepGlobal.matches(Sym.Name))
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Sym.n_type &= ~MachO::N_EXT;
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if (!Sym.isUndefinedSymbol() && Config.SymbolsToGlobalize.matches(Sym.Name))
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Sym.n_type |= MachO::N_EXT;
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if (Sym.isExternalSymbol() && !Sym.isUndefinedSymbol() &&
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(Config.Weaken || Config.SymbolsToWeaken.matches(Sym.Name)))
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Sym.n_desc |= llvm::MachO::N_WEAK_DEF;
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Sym.n_desc |= MachO::N_WEAK_DEF;
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auto I = Config.SymbolsToRename.find(Sym.Name);
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if (I != Config.SymbolsToRename.end())
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Sym.Name = std::string(I->getValue());
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}
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});
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auto RemovePred = [&Config, &MachOConfig,
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&Obj](const std::unique_ptr<SymbolEntry> &N) {

‎llvm/lib/ObjCopy/MachO/MachOObject.cpp

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@@ -33,6 +33,19 @@ SymbolEntry *SymbolTable::getSymbolByIndex(uint32_t Index) {
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static_cast<const SymbolTable *>(this)->getSymbolByIndex(Index));
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}
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void SymbolTable::updateSymbols(function_ref<void(SymbolEntry &)> Callable) {
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for (auto &Sym : Symbols)
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Callable(*Sym);
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// Partition symbols: local < defined external < undefined external.
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auto ExternalBegin = std::stable_partition(
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std::begin(Symbols), std::end(Symbols),
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[](const auto &Sym) { return Sym->isLocalSymbol(); });
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std::stable_partition(ExternalBegin, std::end(Symbols), [](const auto &Sym) {
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return !Sym->isUndefinedSymbol();
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});
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}
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void SymbolTable::removeSymbols(
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function_ref<bool(const std::unique_ptr<SymbolEntry> &)> ToRemove) {
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llvm::erase_if(Symbols, ToRemove);

‎llvm/lib/ObjCopy/MachO/MachOObject.h

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@@ -142,6 +142,7 @@ struct SymbolTable {
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const SymbolEntry *getSymbolByIndex(uint32_t Index) const;
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SymbolEntry *getSymbolByIndex(uint32_t Index);
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void updateSymbols(function_ref<void(SymbolEntry &)> Callable);
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void removeSymbols(
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function_ref<bool(const std::unique_ptr<SymbolEntry> &)> ToRemove);
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};

‎llvm/test/tools/llvm-objcopy/MachO/globalize-symbol.test

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# RUN: yaml2obj %s -o %t
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# RUN: llvm-objcopy --wildcard --globalize-symbol="*" %t %t.copy
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# RUN: llvm-readobj --symbols %t.copy | FileCheck %s
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# RUN: echo "*" > %t-star.txt
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# RUN: llvm-objcopy --wildcard --globalize-symbols="%t-star.txt" %t %t.copy
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# RUN: llvm-readobj --symbols %t.copy | FileCheck %s
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# CHECK: Symbols [
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# CHECK-NEXT: Symbol {
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# CHECK-NEXT: Name: _PrivateSymbol
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# CHECK-NEXT: Extern
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# CHECK-NEXT: Type: Section (0xE)
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# CHECK-NEXT: Section: __text (0x1)
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# CHECK-NEXT: RefType: UndefinedNonLazy (0x0)
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# CHECK-NEXT: Flags [ (0x0)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Value: 0x1
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# CHECK-NEXT: }
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# CHECK-NEXT: Symbol {
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# CHECK-NEXT: Name: _PrivateExternalSymbol
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# CHECK-NEXT: PrivateExtern
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# CHECK-NEXT: Extern
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# CHECK-NEXT: Type: Section (0xE)
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# CHECK-NEXT: Section: __text (0x1)
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# CHECK-NEXT: RefType: UndefinedNonLazy (0x0)
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# CHECK-NEXT: Flags [ (0x0)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Value: 0x2
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# CHECK-NEXT: }
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# CHECK-NEXT: Symbol {
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# CHECK-NEXT: Name: _CommonSymbol
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# CHECK-NEXT: Extern
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# CHECK-NEXT: Type: Section (0xE)
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# CHECK-NEXT: Section: __text (0x1)
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# CHECK-NEXT: RefType: UndefinedNonLazy (0x0)
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# CHECK-NEXT: Flags [ (0x0)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Value: 0x3
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# CHECK-NEXT: }
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# CHECK-NEXT: Symbol {
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# CHECK-NEXT: Name: _UndefinedExternalSymbol
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# CHECK-NEXT: Extern
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# CHECK-NEXT: Type: Undef (0x0)
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# CHECK-NEXT: Section: (0x0)
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# CHECK-NEXT: RefType: UndefinedNonLazy (0x0)
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# CHECK-NEXT: Flags [ (0x0)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Value: 0x0
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# CHECK-NEXT: }
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# CHECK-NEXT: ]
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--- !mach-o
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FileHeader:
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magic: 0xFEEDFACF
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cputype: 0x100000C
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cmdsize: 152
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segname: __TEXT
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vmaddr: 4294967296
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vmsize: 4096
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fileoff: 0
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filesize: 4096
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reserved1: 0x0
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content: 00008052C0035FD6
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- cmd: LC_SEGMENT_64
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cmdsize: 72
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filesize: 67
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cmdsize: 24
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symoff: 4096
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nsyms: 4
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strsize: 79
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LinkEditData:
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NameList:
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- n_strx: 2
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n_type: 0x0E
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n_value: 1
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- n_strx: 17
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StringTable:
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- ' '
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- _CommonSymbol
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- _UndefinedExternalSymbol
134+
...

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