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

Leonardo Santagada via llvm-dev llvm-dev at lists.llvm.org
Fri Jan 19 12:29:26 PST 2018


No I didn't, I used cl.exe from the visual studio toolchain. What I'm
proposing is a tool for processing .obj files in COFF format, reading them
and generating the GHASH part.

To make our build faster we use hundreds of unity build files (.cpp's with
a lot of other .cpp's in them aka munch files) but still have a lot of
single .cpp's as well (in total something like 3.4k .obj files).

ps: sorry for sending to the wrong list, I was reading about llvm mailing
lists and jumped when I saw what I thought was a lld exclusive list.

On Fri, Jan 19, 2018 at 9:17 PM, Zachary Turner <zturner at google.com> wrote:

> -lldb-dev, +llvm-dev
> lldb-dev is specifically for the llvm debugger, and llvm-dev is for
> everything else (including lld)
> Did you compile the object files with clang and use -mllvm
> -emit-codeview-ghash-section?
> It sounds like probably not.  If you don’t do that /DEBUG:GHASH will
> indeed be much slower.  I wonder if we should emit a linker diagnostic in
> this case
> On Fri, Jan 19, 2018 at 12:09 PM Leonardo Santagada via lldb-dev <
> lldb-dev at lists.llvm.org> wrote:
>> Hi all,
>> At work I have been experimenting with linking with lld, I can give all
>> sorts of information about the performance so far if someone wants to hear
>> it, but for a large binary (around 100mb and 800mb of symbols) it takes
>> considerably more memory and time than the vs 2015 and 2017 linker.
>> What I've been playing around is the idea of creating a tool that
>> generate those DEBUG:GHASH sections on .obj files already created, I saw
>> code for reading them in lld and started looking at the codeview part of
>> clang, is there any documentation around that, and would anyone else have
>> interest in such a tool? I wish we could just jump shit to clang but right
>> now that is not a possibility (It mostly revolves around windows.h and the
>> copy of it we mantain).
>> ps: I have two patches that I needed to get it to finish linking I can
>> submit them monday.
>> --
>> Leonardo Santagada
>> _______________________________________________
>> lldb-dev mailing list
>> lldb-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev


Leonardo Santagada
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