[llvm-dev] are the LLD libraries thread safe?
Rui Ueyama via llvm-dev
llvm-dev at lists.llvm.org
Wed Aug 22 00:46:49 PDT 2018
It is unlikely due to the complexity of making everything thread-safe, but
you can probably just invoke lld as a new process or do fork() to run
multiple instances of lld concurrently.
On Wed, Jul 25, 2018 at 8:09 PM Dave Bozier via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Are there any plans to make LLD thread safe in the future? This would be a
> useful feature for us.
>
> Cheers,
>
> Dave
>
> On Wed, Jul 25, 2018 at 10:12 AM James Henderson via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hi Andrew,
>>
>> LLD relies on various bits of global state which are manipulated during
>> the link, so I wouldn't expect it to be thread safe at that level, although
>> it does attempt to reset that global state at the start of each call to
>> link(), so it should be callable sequentially.
>>
>> Regards,
>>
>> James
>>
>> On 25 July 2018 at 02:37, Andrew Kelley via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> 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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>>>
>>>
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