[llvm-dev] lld-link crash when linking intrinsics lib

Wed Feb 27 16:15:34 PST 2019

On Wed, Feb 27, 2019 at 4:11 PM Shi, Steven <steven.shi at intel.com> wrote:

> >Steven,
>
> >Do you need to use LTO? I thought that LTO is a workaround to not produce
> an object file that cannot be handled by your ELF-to-COFF translation tool.
> If you are now doing a regular cross build, I guess you can remove -flto.
>
> Yes, I need the LTO for the smallest code size. Without LTO, my firmware
> image will be +30% larger which is not competitive with MSVC.
>

In the meantime you probably want to experiment clang-cl and lld without
-flto. Once this issue is resolved, you can turn it on.

Thanks
>
> Steven
>
>
>
> *From:* Rui Ueyama [mailto:ruiu at google.com]
> *Sent:* Thursday, February 28, 2019 8:01 AM
> *To:* Shi, Steven <steven.shi at intel.com>; Peter Collingbourne <
> pcc at chromium.org>
> *Cc:* Peter Smith <peter.smith at linaro.org>; Martin Storsjö <
> martin at martin.st>; llvm-dev at lists.llvm.org
> *Subject:* Re: lld-link crash when linking intrinsics lib
>
>
>
> +Peter Collingbourne <pcc at chromium.org>
>
>
>
> LTO is used in this test case, and one source file defines its own
> `memset` function while the other file uses llvm.memset. Looks like LTO is
> confused by the user-defined memset. Could you take a look?
>
>
>
> Steven,
>
>
>
> Do you need to use LTO? I thought that LTO is a workaround to not produce
> an object file that cannot be handled by your ELF-to-COFF translation tool.
> If you are now doing a regular cross build, I guess you can remove -flto.
>
>
>
> On Wed, Feb 27, 2019 at 3:00 PM Rui Ueyama <ruiu at google.com> wrote:
>
> Hi Steven,
>
>
>
> I confirmed that lld-link crashes with these inputs. That shouldn't
> happen. I'll debug this and get back to you. Thank you for reporting.
>
>
>
> On Tue, Feb 26, 2019 at 8:20 PM Shi, Steven <steven.shi at intel.com> wrote:
>
> Hello Rui,
>
> I met couples of lld-link crash when enable the clang-cl + lld-link build
> toolchain for Uefi firmware. Below is a simplified example (main.c and
> intrinsics.c).
>
> Uefi firmware is self-contained and doesn’t depend on the compiler
> intrinsics implementation, so we have our own intrinsics lib. It is weird
> that if I don’t use the llvm-lib but directly “lld-link /NODEFAULTLIB
> /ENTRY:main  main.obj intrinsics.obj”, the below example can pass link.
> Please advise what’s wrong in this example.
>
>
>
>
>
> $ cat main.c
>
> typedef struct {
>
>   struct MAP_LIST {
>
>     unsigned long long  VirtualAddress;
>
>     void              *MapCookie;
>
>   } MapList[100];
>
> } SNP_DRIVER;
>
> SNP_DRIVER snp_instance;
>
> int main()
>
> {
>
>   SNP_DRIVER  *Snp;
>
>   Snp = &snp_instance;
>
>   for (int Index = 0; Index < 100; Index++) {
>
>     Snp->MapList[Index].VirtualAddress = 0;
>
>     Snp->MapList[Index].MapCookie      = 0;
>
>   }
>
>   return 0;
>
> }
>
>
>
> $ cat intrinsics.c
>
> void * memset (void *dest, int ch, size_t count)
>
> {
>
>   volatile char  *Pointer;
>
>   Pointer = (char *)dest;
>
>   while (count-- != 0) {
>
>     *(Pointer++) = (char)ch;
>
>   }
>
>   return dest;
>
> }
>
>
>
>
>
> $ "/home/jshi19/llvm/releaseinstall/bin/clang-cl" /Fomain.obj /c
> --target=x86_64-pc-win32-coff -m64 /O1b2s -flto main.c
>
> $ "/home/jshi19/llvm/releaseinstall/bin/clang-cl" /Fointrinsics.obj /c
> --target=x86_64-pc-win32-coff -m64 /O1b2s -flto intrinsics.c
>
> $ "/home/jshi19/llvm/releaseinstall/bin/llvm-lib" /OUT:intrinsics.lib
> intrinsics.obj
>
> $ "/home/jshi19/llvm/releaseinstall/bin/lld-link" /NODEFAULTLIB
> /ENTRY:main  main.obj intrinsics.lib
>
> Stack dump:
>
> 0.      Program arguments: /home/jshi19/llvm/releaseinstall/bin/lld-link
> /NODEFAULTLIB /ENTRY:main main.obj intrinsics.lib
>
> #0 0x0000559a34ba5e4a llvm::sys::PrintStackTrace(llvm::raw_ostream&)
> (/home/jshi19/llvm/releaseinstall/bin/lld-link+0x272e4a)
>
> #1 0x0000559a34ba3d14 llvm::sys::RunSignalHandlers()
> (/home/jshi19/llvm/releaseinstall/bin/lld-link+0x270d14)
>
> #2 0x0000559a34ba3e52 SignalHandler(int)
> (/home/jshi19/llvm/releaseinstall/bin/lld-link+0x270e52)
>
> #3 0x00007f896c8ea890 __restore_rt
> (/lib/x86_64-linux-gnu/libpthread.so.0+0x12890)
>
> #4 0x0000559a34c11325
> lld::coff::markLive(llvm::ArrayRef<lld::coff::Chunk*>)
> (/home/jshi19/llvm/releaseinstall/bin/lld-link+0x2de325)
>
> #5 0x0000559a34bf0220 lld::coff::LinkerDriver::link(llvm::ArrayRef<char
> const*>) (/home/jshi19/llvm/releaseinstall/bin/lld-link+0x2bd220)
>
> #6 0x0000559a34bf0478 lld::coff::link(llvm::ArrayRef<char const*>, bool,
> llvm::raw_ostream&) (/home/jshi19/llvm/releaseinstall/bin/lld-link+0x2bd478)
>
> #7 0x0000559a34b2a300 main
> (/home/jshi19/llvm/releaseinstall/bin/lld-link+0x1f7300)
>
> #8 0x00007f896b3c1b97 __libc_start_main
> /build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:344:0
>
> #9 0x0000559a34b8c27a _start
> (/home/jshi19/llvm/releaseinstall/bin/lld-link+0x25927a)
>
> Segmentation fault (core dumped)
>
>
>
> $ "/home/jshi19/llvm/releaseinstall/bin/clang-cl" --version
>
> clang version 9.0.0 (https://github.com/llvm-mirror/clang.git
> 1f02068469ff18f5fc5728cafe9d96ee5f66c5b9) (
> https://github.com/llvm-project/llvm.git
> 330395ea4fce35b019b33797ff751be029a1f866)
>
> Target: x86_64-pc-windows-msvc
>
> Thread model: posix
>
> InstalledDir: /home/jshi19/llvm/releaseinstall/bin
>
>
>
> $ "/home/jshi19/llvm/releaseinstall/bin/lld-link" --version
>
> LLD 9.0.0 (https://github.com/llvm-mirror/lld.git
> aa7adc0ec804b689771f11d52e39f83a16378f5f)
>
>
>
>
>
>
>
>
>
> Thanks
>
>
>
> *Steven Shi*
>
> *Intel\SSG\FID\Firmware Infrastructure*
>
>
>
>
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