Crash in llvm::StringTableBuilder::write

[AtomicOperation]

LMK if this isn't the right place for this.

 #0 0x00007f61aab3bbf5 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/coder/git/roblox/master/Client/dependencies/clang/bin/../lib/libLLVM.so.19.1+0x2690bf5)
 #1 0x00007f61aab3986e llvm::sys::RunSignalHandlers() (/home/coder/git/roblox/master/Client/dependencies/clang/bin/../lib/libLLVM.so.19.1+0x268e86e)
 #2 0x00007f61aab3c27f SignalHandler(int) Signals.cpp:0:0
 #3 0x00007f61ad741420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007f61a82f5ae6 /build/glibc-LcI20x/glibc-2.31/string/../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:416:0
 #5 0x00007f61ac44391d llvm::StringTableBuilder::write(unsigned char*) const (/home/coder/git/roblox/master/Client/dependencies/clang/bin/../lib/libLLVM.so.19.1+0x3f9891d)
 #6 0x00007f61aaabfddd std::__1::__function::__func<llvm::parallelFor(unsigned long, unsigned long, llvm::function_ref<void (unsigned long)>)::$_0, std::__1::allocator<llvm::parallelFor(unsigned long, unsigned long, llvm::function_ref<void (unsigned long)>)::$_0>, void ()>::operator()() Parallel.cpp:0:0
 #7 0x00007f61aaabd590 llvm::parallelFor(unsigned long, unsigned long, llvm::function_ref<void (unsigned long)>) (/home/coder/git/roblox/master/Client/dependencies/clang/bin/../lib/libLLVM.so.19.1+0x2612590)
 #8 0x000055bb372f8c4d lld::elf::MergeNoTailSection::writeTo(unsigned char*) (/home/coder/git/roblox/master/Client/dependencies/clang/bin/ld.lld+0x3a9c4d)
 #9 0x000055bb3729d63a void lld::elf::OutputSection::writeTo<llvm::object::ELFType<(llvm::endianness)1, true>>(unsigned char*, llvm::parallel::TaskGroup&)::'lambda'(unsigned long, unsigned long)::operator()(unsigned long, unsigned long) const OutputSections.cpp:0:0
#10 0x00007f61aaabfcca std::__1::__function::__func<llvm::parallel::TaskGroup::spawn(std::__1::function<void ()>, bool)::$_0, std::__1::allocator<llvm::parallel::TaskGroup::spawn(std::__1::function<void ()>, bool)::$_0>, void ()>::operator()() Parallel.cpp:0:0
#11 0x00007f61aaabe59e llvm::parallel::detail::(anonymous namespace)::ThreadPoolExecutor::work(llvm::ThreadPoolStrategy, unsigned int) Parallel.cpp:0:0

Excluding the actual libraries (of which there are a lot) the command line is basically:

clang++
--sysroot=/home/coder/git/roblox/master/Client/dependencies/clang
-stdlib=libc++
-msse4
-D_FORTIFY_SOURCE=0
-fcolor-diagnostics
-DNDEBUG
-Wl,--no-rosegment,--build-id=uuid
-fuse-ld=lld
-lc++abi
-Wl,-z,stack-size=8388608
-fPIC
-fsanitize=address,fuzzer-no-link

This is on Ubuntu 20.04. The runtimes in the sysroot were built with musl, but the binaries weren't.

clang version 19.1.3 (https://github.rbx.com/GameEngine/llvm-project.git b4171ab8ef2bffc38b03887be39c82039d426dff)

[llvmbot]

@llvm/issue-subscribers-lld-elf

Author: None (AtomicOperation)

LMK if this isn't the right place for this.

 #<!-- -->0 0x00007f61aab3bbf5 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) (/home/coder/git/roblox/master/Client/dependencies/clang/bin/../lib/libLLVM.so.19.1+0x2690bf5)
 #<!-- -->1 0x00007f61aab3986e llvm::sys::RunSignalHandlers() (/home/coder/git/roblox/master/Client/dependencies/clang/bin/../lib/libLLVM.so.19.1+0x268e86e)
 #<!-- -->2 0x00007f61aab3c27f SignalHandler(int) Signals.cpp:0:0
 #<!-- -->3 0x00007f61ad741420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #<!-- -->4 0x00007f61a82f5ae6 /build/glibc-LcI20x/glibc-2.31/string/../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:416:0
 #<!-- -->5 0x00007f61ac44391d llvm::StringTableBuilder::write(unsigned char*) const (/home/coder/git/roblox/master/Client/dependencies/clang/bin/../lib/libLLVM.so.19.1+0x3f9891d)
 #<!-- -->6 0x00007f61aaabfddd std::__1::__function::__func&lt;llvm::parallelFor(unsigned long, unsigned long, llvm::function_ref&lt;void (unsigned long)&gt;)::$_0, std::__1::allocator&lt;llvm::parallelFor(unsigned long, unsigned long, llvm::function_ref&lt;void (unsigned long)&gt;)::$_0&gt;, void ()&gt;::operator()() Parallel.cpp:0:0
 #<!-- -->7 0x00007f61aaabd590 llvm::parallelFor(unsigned long, unsigned long, llvm::function_ref&lt;void (unsigned long)&gt;) (/home/coder/git/roblox/master/Client/dependencies/clang/bin/../lib/libLLVM.so.19.1+0x2612590)
 #<!-- -->8 0x000055bb372f8c4d lld::elf::MergeNoTailSection::writeTo(unsigned char*) (/home/coder/git/roblox/master/Client/dependencies/clang/bin/ld.lld+0x3a9c4d)
 #<!-- -->9 0x000055bb3729d63a void lld::elf::OutputSection::writeTo&lt;llvm::object::ELFType&lt;(llvm::endianness)1, true&gt;&gt;(unsigned char*, llvm::parallel::TaskGroup&amp;)::'lambda'(unsigned long, unsigned long)::operator()(unsigned long, unsigned long) const OutputSections.cpp:0:0
#<!-- -->10 0x00007f61aaabfcca std::__1::__function::__func&lt;llvm::parallel::TaskGroup::spawn(std::__1::function&lt;void ()&gt;, bool)::$_0, std::__1::allocator&lt;llvm::parallel::TaskGroup::spawn(std::__1::function&lt;void ()&gt;, bool)::$_0&gt;, void ()&gt;::operator()() Parallel.cpp:0:0
#<!-- -->11 0x00007f61aaabe59e llvm::parallel::detail::(anonymous namespace)::ThreadPoolExecutor::work(llvm::ThreadPoolStrategy, unsigned int) Parallel.cpp:0:0

Excluding the actual libraries (of which there are a lot) the command line is basically:

clang++
--sysroot=/home/coder/git/roblox/master/Client/dependencies/clang
-stdlib=libc++
-msse4
-D_FORTIFY_SOURCE=0
-fcolor-diagnostics
-DNDEBUG
-Wl,--no-rosegment,--build-id=uuid
-fuse-ld=lld
-lc++abi
-Wl,-z,stack-size=8388608
-fPIC
-fsanitize=address,fuzzer-no-link

This is on Ubuntu 20.04. The runtimes in the sysroot were built with musl, but the binaries weren't.

clang version 19.1.3 (https://github.rbx.com/GameEngine/llvm-project.git b4171ab8ef2bffc38b03887be39c82039d426dff)

[rnk]

Can you help differentiate this from an OOM situation? Users have recently reported they get SIGBUS during output writing, which is what's happening here based on the stack trace. What signal are you getting?

Does the problem go away if you link with -Wl,--no-mmap-output-file?