[LLVMdev] LLVM LTO

[Rafael Espíndola]

You should probably send them for review/inclusion in bfd.

On 11 October 2013 12:39, Hal Finkel <hfinkel at anl.gov> wrote:
> Quick update: the previous patch only worked for static linking; this version should work for both static and dynamic linking.
>
> I'm not going to send any more updated patches to this list, but please feel free to e-mail me off-list, and I'll be happy to share any updates I have at any point in the future.
>
>  -Hal
>
> ----- Original Message -----
>> Rafael, Rui,
>>
>> This is obviously an old thread, but in case there is interest, I've
>> been able to get this to work (using the LLVM gold plugin with the
>> ld.bfd linker). This requires some additional logic in the ld.bfd
>> linker (and a small change to the bfd library). I've attached the
>> patch (against binutils HEAD from 2013-09-17) in case anyone finds
>> this useful. The core issue is that ld.bfd is currently setup to use
>> the GCC LTO plugin, which produces its IR in an ELF container, and
>> we don't. As a result, ld.bfd needs to ask the plugin if it would
>> like to claim files of unknown format (in addition to querying for
>> recognized object files).
>>
>>  -Hal
>>
>> P.S. For the record, I'm certainly not a binutils expert, this just
>> seems to work for me.
>>
>> ----- Original Message -----
>> > On 1 August 2012 23:00, Sun, Rui <rui.sun at intel.com> wrote:
>> > > Hi,
>> > >
>> > >
>> > >
>> > > I am trying to use LLVM LTO. I read
>> > > http://llvm.org/docs/GoldPlugin.html and
>> > > have some questions. Could anyone help?
>> > >
>> > >
>> > >
>> > > 1.       Can LLVMgold.so work with BFD LD instead of gold? In the
>> > > description of changes in binutils 2.20, “* The plugin target has
>> > > been added
>> > > to bfd. It can load the same shared objects
>> > >
>> > > used by gold and uses them to provide basic support for new file
>> > > formats.”.
>> > > Does this mean BFD LD after 2.20 can support LLVMgold.so?  Ld
>> > > version on my
>> > > system is:
>> > >
>> > > GNU ld (GNU Binutils for Ubuntu) 2.21.53.20110810
>> > >
>> >
>> > In theory it can, but I think it is completely untested.  I think
>> > that, as with gold, you have to build it with --enable-plugins.
>> >
>> > >
>> > > 2.       Gold only supports ELF. If BFD LD can support LLVMgold,
>> > > can LTO be
>> > > applied to COFF objects after recompiling the binutils with
>> > > target==x86_64-pc-pe?
>> >
>> > Double untested, but I guess it could be made to work :-)
>> >
>> > >
>> > > Thanks!
>> > >
>> > > Rui
>> > >
>> > >
>> >
>> > Cheers,
>> > Rafael
>> >
>> > _______________________________________________
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>> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
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>> >
>>
>> --
>> Hal Finkel
>> Assistant Computational Scientist
>> Leadership Computing Facility
>> Argonne National Laboratory
>
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory