[llvm-dev] are the LLD libraries thread safe?

Andrew Kelley via llvm-dev llvm-dev at lists.llvm.org
Tue Jul 24 18:37:50 PDT 2018 

Follow-up -

Putting a global lock on running LLD indeed solved the issue, so I'm
guessing that the LLD libraries do not in fact support being called from
multiple threads simultaneously.

On Tue, Jul 24, 2018 at 9:10 PM, Andrew Kelley <superjoe30 at gmail.com> wrote:

> E.g. Is it intended to be allowed to call lld::elf::link in 2 different
> threads at the same time?
>
> Follows is an example Valgrind error I ran into when doing the above.
>
> I'll try putting a global resource lock on invoking LLD and see if it
> solves the problem.
>
> ==5467== Invalid write of size 8
> ==5467==    at 0x525509: llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef,
> int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int> >,
> llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::moveFromOldBuckets(llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int>*, llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>*)
> (DenseMap.h:375)
> ==5467==    by 0x524C7F: llvm::DenseMap<llvm::CachedHashStringRef, int,
> llvm::DenseMapInfo<llvm::CachedHashStringRef>, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int> >::grow(unsigned int) (DenseMap.h:739)
> ==5467==    by 0x524077: llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef,
> int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int> >,
> llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::grow(unsigned int) (DenseMap.h:502)
> ==5467==    by 0x522E54: llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int>* llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef, int,
> llvm::DenseMapInfo<llvm::CachedHashStringRef>, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int> >, llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::InsertIntoBucketImpl<llvm::CachedHashStringRef>(llvm::CachedHashStringRef
> const&, llvm::CachedHashStringRef const&, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int>*) (DenseMap.h:546)
> ==5467==    by 0x521258: llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int>* llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef, int,
> llvm::DenseMapInfo<llvm::CachedHashStringRef>, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int> >, llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::InsertIntoBucket<llvm::CachedHashStringRef, int>(llvm::detail::
> DenseMapPair<llvm::CachedHashStringRef, int>*,
> llvm::CachedHashStringRef&&, int&&) (DenseMap.h:512)
> ==5467==    by 0x51DEC9: std::pair<llvm::DenseMapIterator<llvm::CachedHashStringRef,
> int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>, false>, bool>
> llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef, int,
> llvm::DenseMapInfo<llvm::CachedHashStringRef>, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int> >, llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::try_emplace<int>(llvm::CachedHashStringRef&&, int&&) (DenseMap.h:215)
> ==5467==    by 0x51C52F: llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef,
> int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int> >,
> llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::insert(std::pair<llvm::CachedHashStringRef, int>&&) (DenseMap.h:199)
> ==5467==    by 0x516836: lld::elf::SymbolTable::insert(llvm::StringRef)
> (SymbolTable.cpp:225)
> ==5467==    by 0x516A21: lld::elf::SymbolTable::insert(llvm::StringRef,
> unsigned char, unsigned char, bool, lld::elf::InputFile*)
> (SymbolTable.cpp:260)
> ==5467==    by 0x51B88C: void lld::elf::SymbolTable::
> addShared<llvm::object::ELFType<(llvm::support::endianness)1, true>
> >(llvm::StringRef, lld::elf::SharedFile<llvm::object::ELFType<(llvm::support::endianness)1,
> true> >&, llvm::object::ELFType<(llvm::support::endianness)1, true>::Sym
> const&, unsigned int, unsigned int) (SymbolTable.cpp:483)
> ==5467==    by 0x4E762A: lld::elf::SharedFile<llvm::
> object::ELFType<(llvm::support::endianness)1, true> >::parseRest()
> (InputFiles.cpp:895)
> ==5467==    by 0x51F69F: void lld::elf::SymbolTable::
> addFile<llvm::object::ELFType<(llvm::support::endianness)1, true>
> >(lld::elf::InputFile*) (SymbolTable.cpp:99)
> ==5467==  Address 0xc6c7e80 is 53,568 bytes inside a block of size 98,304
> free'd
> ==5467==    at 0x4C2E26B: operator delete(void*) (in /nix/store/
> j7sf6f2i9gws7c5mn8jyi8wc08ab1zbp-valgrind-3.13.0/lib/
> valgrind/vgpreload_memcheck-amd64-linux.so)
> ==5467==    by 0x4C714C: llvm::DenseMap<llvm::CachedHashStringRef, int,
> llvm::DenseMapInfo<llvm::CachedHashStringRef>, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int> >::~DenseMap() (DenseMap.h:681)
> ==5467==    by 0x4C9C7B: lld::elf::SymbolTable::~SymbolTable()
> (SymbolTable.h:36)
> ==5467==    by 0x4C9BF1: llvm::SpecificBumpPtrAllocator<lld::
> elf::SymbolTable>::DestroyAll()::{lambda(char*,
> char*)#1}::operator()(char*, char*) const (Allocator.h:410)
> ==5467==    by 0x4C9D77: llvm::SpecificBumpPtrAllocator<lld::
> elf::SymbolTable>::DestroyAll() (Allocator.h:421)
> ==5467==    by 0x4D218F: lld::SpecificAlloc<lld::elf::SymbolTable>::reset()
> (Memory.h:47)
> ==5467==    by 0x3EF68B: lld::freeArena() (Memory.cpp:21)
> ==5467==    by 0x4B3D41: lld::elf::link(llvm::ArrayRef<char const*>,
> bool, llvm::raw_ostream&) (Driver.cpp:101)
> ==5467==    by 0x39FC06: ZigLLDLink (zig_llvm.cpp:840)
> ==5467==    by 0x38DE74: link.resume (link.zig:84)
> ==5467==    by 0x2475EB: Loop_workerRun (loop.zig:511)
> ==5467==    by 0x2495EC: MainFuncs_posixThreadMain (index.zig:2680)
> ==5467==  Block was alloc'd at
> ==5467==    at 0x4C2D1AF: operator new(unsigned long) (in /nix/store/
> j7sf6f2i9gws7c5mn8jyi8wc08ab1zbp-valgrind-3.13.0/lib/
> valgrind/vgpreload_memcheck-amd64-linux.so)
> ==5467==    by 0x4CD027: llvm::DenseMap<llvm::CachedHashStringRef, int,
> llvm::DenseMapInfo<llvm::CachedHashStringRef>, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int> >::allocateBuckets(unsigned int) (DenseMap.h:794)
> ==5467==    by 0x524C18: llvm::DenseMap<llvm::CachedHashStringRef, int,
> llvm::DenseMapInfo<llvm::CachedHashStringRef>, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int> >::grow(unsigned int) (DenseMap.h:732)
> ==5467==    by 0x524077: llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef,
> int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int> >,
> llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::grow(unsigned int) (DenseMap.h:502)
> ==5467==    by 0x522E54: llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int>* llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef, int,
> llvm::DenseMapInfo<llvm::CachedHashStringRef>, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int> >, llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::InsertIntoBucketImpl<llvm::CachedHashStringRef>(llvm::CachedHashStringRef
> const&, llvm::CachedHashStringRef const&, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int>*) (DenseMap.h:546)
> ==5467==    by 0x521258: llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int>* llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef, int,
> llvm::DenseMapInfo<llvm::CachedHashStringRef>, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int> >, llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::InsertIntoBucket<llvm::CachedHashStringRef, int>(llvm::detail::
> DenseMapPair<llvm::CachedHashStringRef, int>*,
> llvm::CachedHashStringRef&&, int&&) (DenseMap.h:512)
> ==5467==    by 0x51DEC9: std::pair<llvm::DenseMapIterator<llvm::CachedHashStringRef,
> int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>, false>, bool>
> llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef, int,
> llvm::DenseMapInfo<llvm::CachedHashStringRef>, llvm::detail::DenseMapPair<llvm::CachedHashStringRef,
> int> >, llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::try_emplace<int>(llvm::CachedHashStringRef&&, int&&) (DenseMap.h:215)
> ==5467==    by 0x51C52F: llvm::DenseMapBase<llvm::DenseMap<llvm::CachedHashStringRef,
> int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int> >,
> llvm::CachedHashStringRef, int, llvm::DenseMapInfo<llvm::CachedHashStringRef>,
> llvm::detail::DenseMapPair<llvm::CachedHashStringRef, int>
> >::insert(std::pair<llvm::CachedHashStringRef, int>&&) (DenseMap.h:199)
> ==5467==    by 0x516836: lld::elf::SymbolTable::insert(llvm::StringRef)
> (SymbolTable.cpp:225)
> ==5467==    by 0x516A21: lld::elf::SymbolTable::insert(llvm::StringRef,
> unsigned char, unsigned char, bool, lld::elf::InputFile*)
> (SymbolTable.cpp:260)
> ==5467==    by 0x51B88C: void lld::elf::SymbolTable::
> addShared<llvm::object::ELFType<(llvm::support::endianness)1, true>
> >(llvm::StringRef, lld::elf::SharedFile<llvm::object::ELFType<(llvm::support::endianness)1,
> true> >&, llvm::object::ELFType<(llvm::support::endianness)1, true>::Sym
> const&, unsigned int, unsigned int) (SymbolTable.cpp:483)
> ==5467==    by 0x4E762A: lld::elf::SharedFile<llvm::
> object::ELFType<(llvm::support::endianness)1, true> >::parseRest()
> (InputFiles.cpp:895)
>
>
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