llvm dev - Sep 2019 - lld-link with MSVC6 object files

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
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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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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<mailto: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<mailto:llvm-dev at lists.llvm.org>
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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On Sat, 28 Sep 2019, Paul Moran via llvm-dev 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.
I just tested building an object file with MSVC 6.0 and linking it with 
lld, and it mostly works fine.

At first I got errors like these though:

lld-link: error: /safeseh: hello.obj is not compatible with SEH

But by adding -safeseh:no, I was able to link the file just fine.

If the MSVC 6.0 built object file was built with debug info, I get lld 
warnings like these:

lld-link: warning: ignoring section .debug$S with unrecognized magic 0x2
lld-link: warning: ignoring section .debug$T with unrecognized magic 0x2

Is this what you got? Despite these, linking works (but you won't get a 
working debug info).

// Martin