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[llvm-objcopy] Add --skip-symbol and --skip-symbols options (#80873)
Add --skip-symbol and --skip-symbols options that allow to skip symbols when executing other options that can change the symbol's name, binding or visibility, similar to an existing option --keep-symbol that keeps a symbol from being removed by other options.
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‎llvm/docs/CommandGuide/llvm-objcopy.rst‎

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@@ -464,6 +464,19 @@ 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.rst‎

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@@ -175,6 +175,10 @@ Changes to the LLVM tools
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``--set-symbols-visibility`` options for ELF input to change the
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visibility of symbols.
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* llvm-objcopy now supports ``--skip-symbol`` and ``--skip-symbols`` options
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for ELF input to skip the specified symbols when executing other options
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that can change a symbol's name, binding or visibility.
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Changes to LLDB
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---------------------------------
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‎llvm/include/llvm/ObjCopy/CommonConfig.h‎

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@@ -233,6 +233,7 @@ struct CommonConfig {
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NameMatcher UnneededSymbolsToRemove;
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NameMatcher SymbolsToWeaken;
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NameMatcher SymbolsToKeepGlobal;
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NameMatcher SymbolsToSkip;
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// Map options
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StringMap<SectionRename> SectionsToRename;

‎llvm/lib/ObjCopy/ConfigManager.cpp‎

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@@ -15,7 +15,7 @@ namespace objcopy {
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Expected<const COFFConfig &> ConfigManager::getCOFFConfig() const {
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if (!Common.SplitDWO.empty() || !Common.SymbolsPrefix.empty() ||
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!Common.SymbolsPrefixRemove.empty() ||
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!Common.SymbolsPrefixRemove.empty() || !Common.SymbolsToSkip.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() || !Common.SymbolsToWeaken.empty() ||
@@ -34,7 +34,7 @@ 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() ||
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!Common.SymbolsPrefixRemove.empty() || !Common.SymbolsToSkip.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() ||
@@ -56,7 +56,7 @@ Expected<const MachOConfig &> ConfigManager::getMachOConfig() const {
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Expected<const WasmConfig &> ConfigManager::getWasmConfig() const {
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if (!Common.AddGnuDebugLink.empty() || Common.ExtractPartition ||
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!Common.SplitDWO.empty() || !Common.SymbolsPrefix.empty() ||
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!Common.SymbolsPrefixRemove.empty() ||
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!Common.SymbolsPrefixRemove.empty() || !Common.SymbolsToSkip.empty() ||
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!Common.AllocSectionsPrefix.empty() ||
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Common.DiscardMode != DiscardType::None || !Common.SymbolsToAdd.empty() ||
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!Common.SymbolsToGlobalize.empty() || !Common.SymbolsToLocalize.empty() ||
@@ -77,7 +77,7 @@ Expected<const WasmConfig &> ConfigManager::getWasmConfig() const {
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Expected<const XCOFFConfig &> ConfigManager::getXCOFFConfig() const {
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if (!Common.AddGnuDebugLink.empty() || Common.ExtractPartition ||
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!Common.SplitDWO.empty() || !Common.SymbolsPrefix.empty() ||
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!Common.SymbolsPrefixRemove.empty() ||
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!Common.SymbolsPrefixRemove.empty() || !Common.SymbolsToSkip.empty() ||
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!Common.AllocSectionsPrefix.empty() ||
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Common.DiscardMode != DiscardType::None || !Common.AddSection.empty() ||
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!Common.DumpSection.empty() || !Common.SymbolsToAdd.empty() ||

‎llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp‎

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@@ -291,6 +291,9 @@ static Error updateAndRemoveSymbols(const CommonConfig &Config,
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return Error::success();
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Obj.SymbolTable->updateSymbols([&](Symbol &Sym) {
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if (Config.SymbolsToSkip.matches(Sym.Name))
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return;
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// Common and undefined symbols don't make sense as local symbols, and can
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// even cause crashes if we localize those, so skip them.
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if (!Sym.isCommon() && Sym.getShndx() != SHN_UNDEF &&

‎llvm/test/tools/llvm-objcopy/ELF/skip-symbol.test‎

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## This test checks the functionality of options --skip-symbol and --skip-symbols.
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# RUN: yaml2obj %s -o %t.o
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# RUN: echo 'foo[2-3]' > %t.skip.regex
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## Check --skip-symbol functionality when changing symbol bindings.
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# RUN: llvm-objcopy %t.o %t2.o --localize-hidden --skip-symbol=foo3
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# RUN: llvm-readelf -s %t2.o | FileCheck %s --check-prefix=LH-SYM
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# LH-SYM-DAG: LOCAL HIDDEN 1 foo1
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# LH-SYM-DAG: LOCAL HIDDEN 1 foo2
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# LH-SYM-DAG: GLOBAL HIDDEN 1 foo3
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# LH-SYM-DAG: LOCAL HIDDEN 1 foo4
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# LH-SYM-DAG: LOCAL HIDDEN 1 foo5
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## Check --skip-symbols functionality when changing symbol bindings.
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# RUN: llvm-objcopy %t.o %t1.o --localize-hidden --skip-symbols=%t.skip.regex --regex
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# RUN: llvm-readelf -s %t1.o | FileCheck %s --check-prefix=LH-SYMS
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# LH-SYMS-DAG: LOCAL HIDDEN 1 foo1
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# LH-SYMS-DAG: GLOBAL HIDDEN 1 foo2
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# LH-SYMS-DAG: GLOBAL HIDDEN 1 foo3
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# LH-SYMS-DAG: LOCAL HIDDEN 1 foo4
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# LH-SYMS-DAG: LOCAL HIDDEN 1 foo5
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## Check --skip-symbol functionality when changing symbol names.
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# RUN: echo -e "foo1 bar1\nfoo2 bar2" > %t.renames.list
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# RUN: llvm-objcopy %t.o %t4.o --redefine-syms=%t.renames.list \
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# RUN: --skip-symbol='fo*' --wildcard
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# RUN: llvm-readelf -s %t4.o | FileCheck %s --check-prefix=RS-SYM
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# RS-SYM-DAG: foo1
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# RS-SYM-DAG: foo2
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# RS-SYM-DAG: foo3
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# RS-SYM-DAG: foo4
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# RS-SYM-DAG: foo5
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## Check --skip-symbols functionality when changing symbol names.
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# RUN: llvm-objcopy %t.o %t3.o --redefine-syms=%t.renames.list \
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# RUN: --skip-symbols=%t.skip.regex --regex
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# RUN: llvm-readelf -s %t3.o | FileCheck %s --check-prefix=RS-SYMS
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# RS-SYMS-DAG: bar1
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# RS-SYMS-DAG: foo2
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# RS-SYMS-DAG: foo3
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# RS-SYMS-DAG: foo4
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# RS-SYMS-DAG: foo5
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## Check the functionality when using skip options multiple times.
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# RUN: echo "foo3" > %t.symbol0.list
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# RUN: echo "foo4" > %t.symbol1.list
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# RUN: llvm-objcopy %t.o %t5.o --set-symbol-visibility='foo*'=internal --wildcard \
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# RUN: --skip-symbol=foo1 --skip-symbol=foo2 \
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# RUN: --skip-symbols=%t.symbol0.list --skip-symbols=%t.symbol1.list
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# RUN: llvm-readelf -s %t5.o | FileCheck %s --check-prefix=BOTH
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# BOTH-DAG: GLOBAL HIDDEN 1 foo1
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# BOTH-DAG: GLOBAL HIDDEN 1 foo2
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# BOTH-DAG: GLOBAL HIDDEN 1 foo3
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# BOTH-DAG: GLOBAL HIDDEN 1 foo4
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## Only foo5 is not skipped.
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# BOTH-DAG: GLOBAL INTERNAL 1 foo5
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## Check that using an invalid symbol name regex generates an error.
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# RUN: echo '*.' > %t.symbols.regex
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# RUN: not llvm-objcopy %t.o --skip-symbols=%t.symbols.regex --regex 2>&1 | \
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# RUN: FileCheck %s --check-prefix=SYMBOL
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# RUN: not llvm-objcopy %t.o --skip-symbol='*.' --regex 2>&1 | \
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# RUN: FileCheck %s --check-prefix=SYMBOL
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# SYMBOL: error: cannot compile regular expression '*.': repetition-operator operand invalid
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## Check passing an invalid filename generates an error.
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# RUN: not llvm-objcopy %t.o --skip-symbols=no_file 2>&1 | \
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# RUN: FileCheck %s --check-prefix=FILE -DMSG=%errc_ENOENT
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# FILE: error: 'no_file': [[MSG]]
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!ELF
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FileHeader:
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Class: ELFCLASS64
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Data: ELFDATA2LSB
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Type: ET_REL
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Machine: EM_X86_64
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Sections:
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- Name: .text
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Type: SHT_PROGBITS
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Symbols:
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- Name: foo1
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Section: .text
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Binding: STB_GLOBAL
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Other: [ STV_HIDDEN ]
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- Name: foo2
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Section: .text
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Binding: STB_GLOBAL
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Other: [ STV_HIDDEN ]
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- Name: foo3
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Section: .text
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Binding: STB_GLOBAL
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Other: [ STV_HIDDEN ]
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- Name: foo4
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Section: .text
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Binding: STB_GLOBAL
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Other: [ STV_HIDDEN ]
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- Name: foo5
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Section: .text
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Binding: STB_GLOBAL
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Other: [ STV_HIDDEN ]

‎llvm/tools/llvm-objcopy/ObjcopyOptions.cpp‎

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@@ -978,6 +978,15 @@ objcopy::parseObjcopyOptions(ArrayRef<const char *> RawArgsArr,
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addSymbolsFromFile(Config.SymbolsToKeep, DC.Alloc, Arg->getValue(),
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SymbolMatchStyle, ErrorCallback))
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return std::move(E);
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for (auto *Arg : InputArgs.filtered(OBJCOPY_skip_symbol))
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if (Error E = Config.SymbolsToSkip.addMatcher(NameOrPattern::create(
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Arg->getValue(), SymbolMatchStyle, ErrorCallback)))
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return std::move(E);
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for (auto *Arg : InputArgs.filtered(OBJCOPY_skip_symbols))
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if (Error E =
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addSymbolsFromFile(Config.SymbolsToSkip, DC.Alloc, Arg->getValue(),
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SymbolMatchStyle, ErrorCallback))
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return std::move(E);
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for (auto *Arg : InputArgs.filtered(OBJCOPY_add_symbol)) {
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Expected<NewSymbolInfo> SymInfo = parseNewSymbolInfo(Arg->getValue());
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if (!SymInfo)

‎llvm/tools/llvm-objcopy/ObjcopyOpts.td‎

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@@ -206,6 +206,20 @@ defm keep_symbols
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"be repeated to read symbols from many files">,
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MetaVarName<"filename">;
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defm skip_symbol : Eq<"skip-symbol", "Do not change parameters of symbol <symbol> "
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"when executing other options that can change the symbol's "
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"name, binding or visibility">,
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MetaVarName<"symbol">;
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defm skip_symbols
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: Eq<"skip-symbols",
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"Read a list of symbols from <filename> and run as if "
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"--skip-symbol=<symbol> is set for each one. <filename> "
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"contains one symbol per line and may contain comments beginning with "
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"'#'. Leading and trailing whitespace is stripped from each line. May "
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"be repeated to read symbols from many files">,
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MetaVarName<"filename">;
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defm dump_section
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: Eq<"dump-section",
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"Dump contents of section named <section> into file <file>">,

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