[llvm-dev] [lldb-dev] Trying out lld to link windows binaries (using msvc as a compiler)
Zachary Turner via llvm-dev
llvm-dev at lists.llvm.org
Fri Jan 26 11:44:59 PST 2018
We considered that early on, but most object files actually end up in .lib
files so unless there were a way to connect the objects in the .lib to the
corresponding .ghash files, this would disable ghash usage for a large
amount of inputs. Supporting both is an option, but it adds a bit of
complexity and I’m not totally convinced it’s worth it
On Fri, Jan 26, 2018 at 11:38 AM Leonardo Santagada <santagada at gmail.com>
> 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>
>> 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>
>>> 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
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