Re: [GSoC]Bypass assembler when generating LTO object files

[Jan Hubicka <hubicka@kam.mff.cuni.cz>]

Hi,
> 
> 
> > On 08-Apr-2022, at 6:32 PM, Jan Hubicka <hubicka@kam.mff.cuni.cz> wrote:
> > 
> > Ankur,
> >> I was browsing the list of submitted GSoC projects this year and the
> >> project regarding bypassing assembler when generating LTO object files
> >> caught my eye.
> > I apologize for late reply.  I would be very happy to mentor this
> > project.
> 
> Thanks for the reply, but unfortunately, due to some reasons, I would not
> be able to take part in GSoC this year.  
> But the project seems interesting and would be amazing opportunity to
> learn a lot more things for me, so would it be okay if I try to give it a
> go outside GSoC if no-one else picks it as their GSoC project this year ?

I would be still very happy to help with that! However it would be also
pity to not take part of GSoC, so if there is something I can help with
on that let me know.
> 
> >> 
> >> I already have a gcc built from source (sync-ed with trunk/master) and
> >> launched the test-suite on it.
> >> 
> >> I am currently in process of understanding the primilary patch
> >> (https://gcc.gnu.org/legacy-ml/gcc/2014-09/msg00340.html), and
> >> experimenting with it.
> >> 
> >> are there any other things I should be aware of (useful Doc/blog or a
> >> bug tracking the project) before proceeding further ?
> > 
> > I think it is pretty much all that exists.  Basically we will need to
> > implement everything that is necessary to stream out valid object file
> > directly from GCC rather than going through gas.  The experimental
> > prototype sort of worked but it was lacking few things.
> 
> When I try to apply that patch on my local branch ( branched from trunk ),
> it seem to be incompatible with the current working tree. Is there a
> specific branch that I have to apply it to ? or is it due to the recent
> file rename patch ( changing extensions from .c to .cc ) ? 
> 
> ```
> $ git apply --check bypass_asm_patch
> 
> error: patch failed: Makefile.in:1300
> error: Makefile.in: patch does not apply
> error: common.opt: No such file or directory
> error: langhooks.c: No such file or directory
> error: lto/Make-lang.in: No such file or directory
> error: lto/lto-object.c: No such file or directory
> error: lto/lto.c: No such file or directory
> error: lto/lto.h: No such file or directory
> error: lto-streamer.h: No such file or directory
> error: toplev.c: No such file or directory
> ```

I can try to update the patch, or it probably should apply to trunk
checked out around the date I sent the patch.  Indeed we need to change
c to cc but there are likely more changes since then - most importnatly
the early debug info.
At I will see how easy/hard is to make the patch build with current
trunk.
Honza
> 
> Thanks 
> - Ankur 
>