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Re: GSoC 2018: Hrishikesh Kulkarni has been selected to work on LTO dumping tool

On Sat, Apr 28, 2018 at 5:36 PM, Hrishikesh Kulkarni
<> wrote:
> Hi,
> I have created a new file lto-dump.c and to test if it's linked
> correctly, I have put a dummy function called dump which should simply
> print hello world after passing -dump option to lto1.
> ~/gnu-toolchain/gcc/master/tests$ ../stage1-build/gcc/lto1 hello.o -fdump
> Now while adding -fdump option in lang.opt for command line option I
> am getting error “unrecognised  command line option '-fdump' ”.
> So how should I proceed with adding this new option.
> Please find the diff file attached.

+LTO Dump Tool
+Call the dump function.


Call the dump function.

instead.  The second line is magic flags that need to be recognized.
You probably want instead

LTO Var(flag_lto_dump)

so you can test whether the flag is set or not as well.

Sorry for the late response.


> Thanks,
> Hrishikesh
> On Wed, Apr 25, 2018 at 1:35 PM, Richard Biener
> <> wrote:
>> On Wed, Apr 25, 2018 at 5:17 AM, Hrishikesh Kulkarni
>> <> wrote:
>>> Hi,
>>> Thanks a lot for giving me this wonderful opportunity to work with GCC
>>> under your guidance and mentorship (GSOC 2018).
>>> Just a few starting queries
>>>    1.
>>>    As a starting point to read lto-object file, is it sufficient to only
>>>    link with lto-object.c or shall I need other source files too ?
>> You will need a lot more source files - starting with libbackend.a is
>> probably easiest.  As said during the initial project discussion it
>> remains to be seen whether a fully standalone dump tool is
>> best or whether the actual work is to be done by lto1 and the dump
>> tool shall act merely as a driver around that and they communicate
>> via some special (set of) options to lto1.
>> IIRC we do not have any existing tool that builds trees or cgraph
>> nodes or reads gimple bodies, so picking pices that are required
>> is going to be "interesting" (and eventually will suggest some refactoring
>> to avoid pulling in unnecessary stuff).  You'll also run into issues expecting
>> some initialized global state.  So...
>> ...for the first phase of experimenting with the code-base it's probably
>> easiest to add some testing option to gcc/lto/lang.opt and "do stuff"
>> within a if (flag_your_option) conditional from some point in
>> lto/lto.c:lto_main.
>>>    2.
>>>    Should the dump tool be under gcc or lto dir? Would I need to modify
>>>    only gcc/ to add entry for building the dump tool or any other
>>>    Makefiles too ?
>> I'd say it most naturally would reside in gcc/lto/ and thus its
>> would need to be adjusted.
>>> Also, I would proceed with copyright assignment as soon as I will receive
>>> the mentioned forms.
>>> Thanks,
>>> Hrishikesh
>>> On Tue, Apr 24, 2018 at 6:27 PM, Martin Jambor <> wrote:
>>>> Hello,
>>>> I am pleased to announce that Hrishikesh Kulkarni will be working on
>>>> "Textual Representation of LTO Object Files (Textual LTO dump tool
>>>> project)" as his Google Summer of Code 2018 project.  I believe I write
>>>> on behalf of everybody in the GCC community when I congratulate him and
>>>> wish him success in the upcoming work.  Hrishikesh's mentors are Martin
>>>> Liška and Jan Hubička, but the plan is to have most of the conversation
>>>> about the project on the mailing list and so I would like to encourage
>>>> everyone to help him out here if they can.
>>>> According to the schedule of GSoC, we have entered "Community Bonding
>>>> period" which lasts until May 14th (when the first out of three "coding"
>>>> periods begin).  Hrishikesh, Martin and Honza will take over from me in
>>>> suggesting what technical things you should study/play with, but I'd
>>>> like to request that you make sure you get an FSF copyright assignment
>>>> quickly (see  David, I
>>>> assume that Hrishikesh does not have the assignment yet, can you please
>>>> send him the necessary forms?  Hrishikesh, please fill them is when you
>>>> get and send them to FSF.  If at any moment it will appear that the
>>>> process got stuck, please let me know sooner rather than later.
>>>> On a general note, GCC was given two student slots which we requested
>>>> after receiving two high-quality student proposals.  Unfortunately,
>>>> Sebastiaan has withdrawn from GSoC 2018 before selection was announced
>>>> and so we "only" have one student this year.
>>>> I'm looking forward to the new tool,
>>>> Martin

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