llvm dev - Jan 2018 - [lldb-dev] Trying out lld to link windows binaries (using msvc as a compiler)

Okay, apparently coff2yaml and yaml2coff are not in a great place as they
both don't deal well with the fact that you can have overlapping sections,
which seems to be what clang-cl produces (the .data section points to the
same place as a later section). Which is not a big big problem for me
particularly because msvc doesn't even generate .data sections in .obj.

I'm trying to put support for .bss sections in both coff2yaml and
yaml2coff... but I still can link just fine with my transformations
clang-cl generated files... what does give me problems is msvc .obj files.
Have you tried to link one of these?

On Fri, Jan 26, 2018 at 8:05 PM, Leonardo Santagada <santagada at
gmail.com>
wrote:
> yeah, apparently .bss has a flag of unitialized data that is not being
> respected on the layout of the coff files (it should skip those sections)
> but I dunno what to do with .data as it doesn't have a size.
>
> (resending as apparently my pastes generated a ton of hidden html data and
> this message hit the mailinglist limit of 100k)
> --
>
> Leonardo Santagada
>


-- 

Leonardo Santagada
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20180126/f8d60edf/attachment.html>

In general, we should be able to accept any MSVC .obj file to LLD.  At the
very least, we're not aware of any cases that don't work.

Does your MSVC .obj file link fine before you add the .debug$H?

On Fri, Jan 26, 2018 at 11:23 AM Leonardo Santagada <santagada at
gmail.com>
wrote:
> Okay, apparently coff2yaml and yaml2coff are not in a great place as they
> both don't deal well with the fact that you can have overlapping
sections,
> which seems to be what clang-cl produces (the .data section points to the
> same place as a later section). Which is not a big big problem for me
> particularly because msvc doesn't even generate .data sections in .obj.
>
> I'm trying to put support for .bss sections in both coff2yaml and
> yaml2coff... but I still can link just fine with my transformations
> clang-cl generated files... what does give me problems is msvc .obj files.
> Have you tried to link one of these?
>
> On Fri, Jan 26, 2018 at 8:05 PM, Leonardo Santagada <santagada at
gmail.com>
> wrote:
>
>> yeah, apparently .bss has a flag of unitialized data that is not being
>> respected on the layout of the coff files (it should skip those
sections)
>> but I dunno what to do with .data as it doesn't have a size.
>>
>> (resending as apparently my pastes generated a ton of hidden html data
>> and this message hit the mailinglist limit of 100k)
>> --
>>
>> Leonardo Santagada
>>
>
>
>
> --
>
> Leonardo Santagada
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20180126/5a85bf58/attachment.html>

it does.

I just had an epiphany: why not just write a .ghash file and have lld read
those if they exist for an .obj file?

Seem much simpler than trying to wire up a 20 year old file format. I will
try to do this, is something like this acceptable for LLD? The cool thing
is that I can generate .ghash for .lib or any obj lying around (maybe even
for pdb in the future).

On Fri, Jan 26, 2018 at 8:32 PM, Zachary Turner <zturner at google.com>
wrote:
> In general, we should be able to accept any MSVC .obj file to LLD.  At the
> very least, we're not aware of any cases that don't work.
>
> Does your MSVC .obj file link fine before you add the .debug$H?
>
> On Fri, Jan 26, 2018 at 11:23 AM Leonardo Santagada <santagada at
gmail.com>
> wrote:
>
>> Okay, apparently coff2yaml and yaml2coff are not in a great place as
they
>> both don't deal well with the fact that you can have overlapping
sections,
>> which seems to be what clang-cl produces (the .data section points to
the
>> same place as a later section). Which is not a big big problem for me
>> particularly because msvc doesn't even generate .data sections in
.obj.
>>
>> I'm trying to put support for .bss sections in both coff2yaml and
>> yaml2coff... but I still can link just fine with my transformations
>> clang-cl generated files... what does give me problems is msvc .obj
files.
>> Have you tried to link one of these?
>>
>> On Fri, Jan 26, 2018 at 8:05 PM, Leonardo Santagada <santagada at
gmail.com>
>> wrote:
>>
>>> yeah, apparently .bss has a flag of unitialized data that is not
being
>>> respected on the layout of the coff files (it should skip those
sections)
>>> but I dunno what to do with .data as it doesn't have a size.
>>>
>>> (resending as apparently my pastes generated a ton of hidden html
data
>>> and this message hit the mailinglist limit of 100k)
>>> --
>>>
>>> Leonardo Santagada
>>>
>>
>>
>>
>> --
>>
>> Leonardo Santagada
>>
>

-- 

Leonardo Santagada
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20180126/e41d11ab/attachment.html>