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[lld-macho] Link against libatomic when necessary#144259

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Oct 27, 2025
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[lld-macho] Link against libatomic when necessary#144259
smeenai merged 2 commits into
llvm:mainfrom
sertonix:lld-macho-libatomic

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@sertonix sertonix commented Jun 15, 2025

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In Driver.cpp std::atomic<uint64_t> is used which may need libatomic.

Build failure (if that is of interest):

[127/135] Linking CXX shared library lib/liblldMachO.so.20.1
ninja: job failed: : && /usr/lib/ccache/bin/clang++-20 -fPIC -Os -fstack-clash-protection -Wformat -Werror=format-security -D_GLIBCXX_ASSERTIONS=1 -D_LIBCPP_ENABLE_THREAD_SAFETY_ANNOTATIONS=1 -D_LIBCPP_ENABLE_HARDENED_MODE=1 -g -O2 -DNDEBUG -g1 -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections  -Wl,--as-needed,-O1,--sort-common -Wl,-z,defs -Wl,-z,nodelete   -Wl,-rpath-link,/home/user/aports/main/lld20/src/lld-20.1.5.src/build/./lib  -Wl,--gc-sections -shared -Wl,-soname,liblldMachO.so.20.1 -o lib/liblldMachO.so.20.1 MachO/CMakeFiles/lldMachO.dir/Arch/ARM64.cpp.o MachO/CMakeFiles/lldMachO.dir/Arch/ARM64Common.cpp.o MachO/CMakeFiles/lldMachO.dir/Arch/ARM64_32.cpp.o MachO/CMakeFiles/lldMachO.dir/Arch/X86_64.cpp.o MachO/CMakeFiles/lldMachO.dir/ConcatOutputSection.cpp.o MachO/CMakeFiles/lldMachO.dir/Driver.cpp.o MachO/CMakeFiles/lldMachO.dir/DriverUtils.cpp.o MachO/CMakeFiles/lldMachO.dir/Dwarf.cpp.o MachO/CMakeFiles/lldMachO.dir/EhFrame.cpp.o MachO/CMakeFiles/lldMachO.dir/ExportTrie.cpp.o MachO/CMakeFiles/lldMachO.dir/ICF.cpp.o MachO/CMakeFiles/lldMachO.dir/InputFiles.cpp.o MachO/CMakeFiles/lldMachO.dir/InputSection.cpp.o MachO/CMakeFiles/lldMachO.dir/LTO.cpp.o MachO/CMakeFiles/lldMachO.dir/MapFile.cpp.o MachO/CMakeFiles/lldMachO.dir/MarkLive.cpp.o MachO/CMakeFiles/lldMachO.dir/ObjC.cpp.o MachO/CMakeFiles/lldMachO.dir/OutputSection.cpp.o MachO/CMakeFiles/lldMachO.dir/OutputSegment.cpp.o MachO/CMakeFiles/lldMachO.dir/Relocations.cpp.o MachO/CMakeFiles/lldMachO.dir/BPSectionOrderer.cpp.o MachO/CMakeFiles/lldMachO.dir/SectionPriorities.cpp.o MachO/CMakeFiles/lldMachO.dir/Sections.cpp.o MachO/CMakeFiles/lldMachO.dir/SymbolTable.cpp.o MachO/CMakeFiles/lldMachO.dir/Symbols.cpp.o MachO/CMakeFiles/lldMachO.dir/SyntheticSections.cpp.o MachO/CMakeFiles/lldMachO.dir/Target.cpp.o MachO/CMakeFiles/lldMachO.dir/UnwindInfoSection.cpp.o MachO/CMakeFiles/lldMachO.dir/Writer.cpp.o -L/usr/lib/llvm20/lib -Wl,-rpath,"\$ORIGIN/../lib:/usr/lib/llvm20/lib:/home/user/aports/main/lld20/src/lld-20.1.5.src/build/lib:"  lib/liblldCommon.so.20.1  /usr/lib/llvm20/lib/libLLVM.so.20.1 && :
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../powerpc-alpine-linux-musl/bin/ld: MachO/CMakeFiles/lldMachO.dir/Driver.cpp.o: in function `handleExplicitExports()':
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../include/c++/14.3.0/bits/atomic_base.h:501:(.text._ZL21handleExplicitExportsv+0xb8): undefined reference to `__atomic_load_8'
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../powerpc-alpine-linux-musl/bin/ld: /usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../include/c++/14.3.0/bits/atomic_base.h:501:(.text._ZL21handleExplicitExportsv+0x180): undefined reference to `__atomic_load_8'
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../powerpc-alpine-linux-musl/bin/ld: MachO/CMakeFiles/lldMachO.dir/Driver.cpp.o: in function `void llvm::function_ref<void (unsigned int)>::callback_fn<llvm::parallelForEach<lld::macho::Symbol* const*, handleExplicitExports()::$_0>(lld::macho::Symbol* const*, lld::macho::Symbol* const*, handleExplicitExports()::$_0)::{lambda(unsigned int)#1}>(int, unsigned int)':
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../include/c++/14.3.0/bits/atomic_base.h:631:(.text._ZN4llvm12function_refIFvjEE11callback_fnIZNS_15parallelForEachIPKPN3lld5macho6SymbolEZL21handleExplicitExportsvE3$_0EEvT_SC_T0_EUljE_EEvij+0xd4): undefined reference to `__atomic_fetch_add_8'
clang++-20: error: linker command failed with exit code 1 (use -v to see invocation)

CC @int3 @gkmhub @smeenai

Similar to f0b451c

In Driver.cpp std::atomic<uint64_t> is used which may need libatomic.
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llvmbot commented Jun 15, 2025

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Author: Sertonix (sertonix)

Changes

In Driver.cpp std::atomic&lt;uint64_t&gt; is used which may need libatomic.

Build failure (if that is of interest):

[127/135] Linking CXX shared library lib/liblldMachO.so.20.1
ninja: job failed: : &amp;&amp; /usr/lib/ccache/bin/clang++-20 -fPIC -Os -fstack-clash-protection -Wformat -Werror=format-security -D_GLIBCXX_ASSERTIONS=1 -D_LIBCPP_ENABLE_THREAD_SAFETY_ANNOTATIONS=1 -D_LIBCPP_ENABLE_HARDENED_MODE=1 -g -O2 -DNDEBUG -g1 -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections  -Wl,--as-needed,-O1,--sort-common -Wl,-z,defs -Wl,-z,nodelete   -Wl,-rpath-link,/home/user/aports/main/lld20/src/lld-20.1.5.src/build/./lib  -Wl,--gc-sections -shared -Wl,-soname,liblldMachO.so.20.1 -o lib/liblldMachO.so.20.1 MachO/CMakeFiles/lldMachO.dir/Arch/ARM64.cpp.o MachO/CMakeFiles/lldMachO.dir/Arch/ARM64Common.cpp.o MachO/CMakeFiles/lldMachO.dir/Arch/ARM64_32.cpp.o MachO/CMakeFiles/lldMachO.dir/Arch/X86_64.cpp.o MachO/CMakeFiles/lldMachO.dir/ConcatOutputSection.cpp.o MachO/CMakeFiles/lldMachO.dir/Driver.cpp.o MachO/CMakeFiles/lldMachO.dir/DriverUtils.cpp.o MachO/CMakeFiles/lldMachO.dir/Dwarf.cpp.o MachO/CMakeFiles/lldMachO.dir/EhFrame.cpp.o MachO/CMakeFiles/lldMachO.dir/ExportTrie.cpp.o MachO/CMakeFiles/lldMachO.dir/ICF.cpp.o MachO/CMakeFiles/lldMachO.dir/InputFiles.cpp.o MachO/CMakeFiles/lldMachO.dir/InputSection.cpp.o MachO/CMakeFiles/lldMachO.dir/LTO.cpp.o MachO/CMakeFiles/lldMachO.dir/MapFile.cpp.o MachO/CMakeFiles/lldMachO.dir/MarkLive.cpp.o MachO/CMakeFiles/lldMachO.dir/ObjC.cpp.o MachO/CMakeFiles/lldMachO.dir/OutputSection.cpp.o MachO/CMakeFiles/lldMachO.dir/OutputSegment.cpp.o MachO/CMakeFiles/lldMachO.dir/Relocations.cpp.o MachO/CMakeFiles/lldMachO.dir/BPSectionOrderer.cpp.o MachO/CMakeFiles/lldMachO.dir/SectionPriorities.cpp.o MachO/CMakeFiles/lldMachO.dir/Sections.cpp.o MachO/CMakeFiles/lldMachO.dir/SymbolTable.cpp.o MachO/CMakeFiles/lldMachO.dir/Symbols.cpp.o MachO/CMakeFiles/lldMachO.dir/SyntheticSections.cpp.o MachO/CMakeFiles/lldMachO.dir/Target.cpp.o MachO/CMakeFiles/lldMachO.dir/UnwindInfoSection.cpp.o MachO/CMakeFiles/lldMachO.dir/Writer.cpp.o -L/usr/lib/llvm20/lib -Wl,-rpath,"\$ORIGIN/../lib:/usr/lib/llvm20/lib:/home/user/aports/main/lld20/src/lld-20.1.5.src/build/lib:"  lib/liblldCommon.so.20.1  /usr/lib/llvm20/lib/libLLVM.so.20.1 &amp;&amp; :
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../powerpc-alpine-linux-musl/bin/ld: MachO/CMakeFiles/lldMachO.dir/Driver.cpp.o: in function `handleExplicitExports()':
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../include/c++/14.3.0/bits/atomic_base.h:501:(.text._ZL21handleExplicitExportsv+0xb8): undefined reference to `__atomic_load_8'
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../powerpc-alpine-linux-musl/bin/ld: /usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../include/c++/14.3.0/bits/atomic_base.h:501:(.text._ZL21handleExplicitExportsv+0x180): undefined reference to `__atomic_load_8'
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../powerpc-alpine-linux-musl/bin/ld: MachO/CMakeFiles/lldMachO.dir/Driver.cpp.o: in function `void llvm::function_ref&lt;void (unsigned int)&gt;::callback_fn&lt;llvm::parallelForEach&lt;lld::macho::Symbol* const*, handleExplicitExports()::$_0&gt;(lld::macho::Symbol* const*, lld::macho::Symbol* const*, handleExplicitExports()::$_0)::{lambda(unsigned int)#<!-- -->1}&gt;(int, unsigned int)':
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../include/c++/14.3.0/bits/atomic_base.h:631:(.text._ZN4llvm12function_refIFvjEE11callback_fnIZNS_15parallelForEachIPKPN3lld5macho6SymbolEZL21handleExplicitExportsvE3$_0EEvT_SC_T0_EUljE_EEvij+0xd4): undefined reference to `__atomic_fetch_add_8'
clang++-20: error: linker command failed with exit code 1 (use -v to see invocation)

CC @int3 @gkmhub @smeenai


Full diff: https://github.com/llvm/llvm-project/pull/144259.diff

1 Files Affected:

  • (modified) lld/MachO/CMakeLists.txt (+1)
diff --git a/lld/MachO/CMakeLists.txt b/lld/MachO/CMakeLists.txt
index ecf6ce609e59f..433ac4ec85853 100644
--- a/lld/MachO/CMakeLists.txt
+++ b/lld/MachO/CMakeLists.txt
@@ -58,6 +58,7 @@ add_lld_library(lldMachO
   LINK_LIBS
   lldCommon
   ${LLVM_PTHREAD_LIB}
+  ${LLVM_ATOMIC_LIB}
 
   DEPENDS
   MachOOptionsTableGen

@sertonix

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Is there anything preventing this from being reviewd/merged?

@smeenai smeenai left a comment

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Apologies, I completely missed this. Do you need me to land this for you?

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Do you need me to land this for you?

I think I do. I don't know how this would work otherwise.

@smeenai smeenai enabled auto-merge (squash) October 27, 2025 23:12
@smeenai smeenai merged commit 31417ba into llvm:main Oct 27, 2025
9 of 10 checks passed
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@sertonix Congratulations on having your first Pull Request (PR) merged into the LLVM Project!

Your changes will be combined with recent changes from other authors, then tested by our build bots. If there is a problem with a build, you may receive a report in an email or a comment on this PR.

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If your change does cause a problem, it may be reverted, or you can revert it yourself. This is a normal part of LLVM development. You can fix your changes and open a new PR to merge them again.

If you don't get any reports, no action is required from you. Your changes are working as expected, well done!

@smeenai

smeenai commented Oct 28, 2025

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Do you need me to land this for you?

I think I do. I don't know how this would work otherwise.

Sorry, I completely missed this. Merged now, thank you for the contribution and apologies for the long turnaround!

Lukacma pushed a commit to Lukacma/llvm-project that referenced this pull request Oct 29, 2025
In `Driver.cpp` `std::atomic<uint64_t>` is used which may need
libatomic.

Build failure (if that is of interest):
```
[127/135] Linking CXX shared library lib/liblldMachO.so.20.1
ninja: job failed: : && /usr/lib/ccache/bin/clang++-20 -fPIC -Os -fstack-clash-protection -Wformat -Werror=format-security -D_GLIBCXX_ASSERTIONS=1 -D_LIBCPP_ENABLE_THREAD_SAFETY_ANNOTATIONS=1 -D_LIBCPP_ENABLE_HARDENED_MODE=1 -g -O2 -DNDEBUG -g1 -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections  -Wl,--as-needed,-O1,--sort-common -Wl,-z,defs -Wl,-z,nodelete   -Wl,-rpath-link,/home/user/aports/main/lld20/src/lld-20.1.5.src/build/./lib  -Wl,--gc-sections -shared -Wl,-soname,liblldMachO.so.20.1 -o lib/liblldMachO.so.20.1 MachO/CMakeFiles/lldMachO.dir/Arch/ARM64.cpp.o MachO/CMakeFiles/lldMachO.dir/Arch/ARM64Common.cpp.o MachO/CMakeFiles/lldMachO.dir/Arch/ARM64_32.cpp.o MachO/CMakeFiles/lldMachO.dir/Arch/X86_64.cpp.o MachO/CMakeFiles/lldMachO.dir/ConcatOutputSection.cpp.o MachO/CMakeFiles/lldMachO.dir/Driver.cpp.o MachO/CMakeFiles/lldMachO.dir/DriverUtils.cpp.o MachO/CMakeFiles/lldMachO.dir/Dwarf.cpp.o MachO/CMakeFiles/lldMachO.dir/EhFrame.cpp.o MachO/CMakeFiles/lldMachO.dir/ExportTrie.cpp.o MachO/CMakeFiles/lldMachO.dir/ICF.cpp.o MachO/CMakeFiles/lldMachO.dir/InputFiles.cpp.o MachO/CMakeFiles/lldMachO.dir/InputSection.cpp.o MachO/CMakeFiles/lldMachO.dir/LTO.cpp.o MachO/CMakeFiles/lldMachO.dir/MapFile.cpp.o MachO/CMakeFiles/lldMachO.dir/MarkLive.cpp.o MachO/CMakeFiles/lldMachO.dir/ObjC.cpp.o MachO/CMakeFiles/lldMachO.dir/OutputSection.cpp.o MachO/CMakeFiles/lldMachO.dir/OutputSegment.cpp.o MachO/CMakeFiles/lldMachO.dir/Relocations.cpp.o MachO/CMakeFiles/lldMachO.dir/BPSectionOrderer.cpp.o MachO/CMakeFiles/lldMachO.dir/SectionPriorities.cpp.o MachO/CMakeFiles/lldMachO.dir/Sections.cpp.o MachO/CMakeFiles/lldMachO.dir/SymbolTable.cpp.o MachO/CMakeFiles/lldMachO.dir/Symbols.cpp.o MachO/CMakeFiles/lldMachO.dir/SyntheticSections.cpp.o MachO/CMakeFiles/lldMachO.dir/Target.cpp.o MachO/CMakeFiles/lldMachO.dir/UnwindInfoSection.cpp.o MachO/CMakeFiles/lldMachO.dir/Writer.cpp.o -L/usr/lib/llvm20/lib -Wl,-rpath,"\$ORIGIN/../lib:/usr/lib/llvm20/lib:/home/user/aports/main/lld20/src/lld-20.1.5.src/build/lib:"  lib/liblldCommon.so.20.1  /usr/lib/llvm20/lib/libLLVM.so.20.1 && :
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../powerpc-alpine-linux-musl/bin/ld: MachO/CMakeFiles/lldMachO.dir/Driver.cpp.o: in function `handleExplicitExports()':
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../include/c++/14.3.0/bits/atomic_base.h:501:(.text._ZL21handleExplicitExportsv+0xb8): undefined reference to `__atomic_load_8'
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../powerpc-alpine-linux-musl/bin/ld: /usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../include/c++/14.3.0/bits/atomic_base.h:501:(.text._ZL21handleExplicitExportsv+0x180): undefined reference to `__atomic_load_8'
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../powerpc-alpine-linux-musl/bin/ld: MachO/CMakeFiles/lldMachO.dir/Driver.cpp.o: in function `void llvm::function_ref<void (unsigned int)>::callback_fn<llvm::parallelForEach<lld::macho::Symbol* const*, handleExplicitExports()::$_0>(lld::macho::Symbol* const*, lld::macho::Symbol* const*, handleExplicitExports()::$_0)::{lambda(unsigned int)#1}>(int, unsigned int)':
/usr/lib/gcc/powerpc-alpine-linux-musl/14.3.0/../../../../include/c++/14.3.0/bits/atomic_base.h:631:(.text._ZN4llvm12function_refIFvjEE11callback_fnIZNS_15parallelForEachIPKPN3lld5macho6SymbolEZL21handleExplicitExportsvE3$_0EEvT_SC_T0_EUljE_EEvij+0xd4): undefined reference to `__atomic_fetch_add_8'
clang++-20: error: linker command failed with exit code 1 (use -v to see invocation)
```

CC @int3 @gkmhub @smeenai

Similar to
llvm@f0b451c
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