[llvm-dev] lld-link with MSVC6 object files

David Blaikie via llvm-dev
Mon, 30 Sep 2019 21:14:11 -0000

On Mon, Sep 30, 2019 at 2:07 PM Paul Moran <bankybooks at gmail.com>
wrote:

> MSVC 6 is 1998 not 1989 :)
>

Ah, I just glanced briefly at the Wikipedia article (
https://en.wikipedia.org/wiki/Microsoft_Visual_C%2B%2B ) & misread the
"C
6.0" and didn't notice it was distinct from "Visual C++ 6.0"
- thanks for
the catch!


>
> The latest MSVC linker can link these object files. Is this just because
> it has support for C13 types and some other code path for whatever MSVC6
> uses? After some digging around it appears to be this format:
>
>
>
https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#coff-file-header-object-and-image
>
>
> Which is COFF object file format? Does lld link support this format?
>

COFF is still the windows object file format, and the Windows support in
lld is COFF support, yeah. I guess there might be some format variations
that haven't been implemented in lld, though. It's mostly an "on
demand"
sort of approach.


>
>
> On Mon, Sep 30, 2019 at 7:39 PM Alexandre Ganea <
> alexandre.ganea at ubisoft.com> wrote:
>
>> The CodeView library in LLVM only supports Codeview C13 types, that is,
>> MSVC 7.0 / Visual Studio 2002 or after.
>>
>>
>>
>> *De :* llvm-dev <llvm-dev-bounces at lists.llvm.org> *De la part
de* David
>> Blaikie via llvm-dev
>> *Envoyé :* September 30, 2019 2:38 PM
>> *À :* Paul Moran <bankybooks at gmail.com>; Rui Ueyama <ruiu
at google.com>
>> *Cc :* llvm-dev at lists.llvm.org
>> *Objet :* Re: [llvm-dev] lld-link with MSVC6 object files
>>
>>
>>
>> MSVC 6 as in the Visual Studio released in 1989? Yes, I imagine
that's a
>> bit outside the intended support window.
>>
>>
>>
>> On Mon, Sep 30, 2019 at 11:18 AM Paul Moran via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>> Hi,
>>
>>
>>
>> I have a question about lld-link. What obj file formats should it
>> support? When I try to use an obj from msvc 6.0 it complains that the
file
>> magic is not valid.
>>
>>
>>
>> However when running  llvm-objdump it reports:
>>
>>
>>
>> test1.obj:      file format COFF-i386
>>
>> Disassembly of section .text:
>> 0000000000000000 _main:
>>        0:       68 00 00 00 00  pushl   $0
>>        5:       e8 00 00 00 00  calll   0 <_main+0xa>
>>        a:       83 c4 04        addl    $4, %esp
>>        d:       33 c0   xorl    %eax, %eax
>>
>>       f:       c3      retl
>>
>>
>>
>> Thanks,
>>
>> Paul
>>
>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
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