[llvmlinux] Supporting LLVM IR output during build process

Jason Gionta jjgionta at ncsu.edu
Fri Dec 5 03:17:17 UTC 2014


Thanks for the clarification. I really appreciate it. Do you think getting
the IR->vmlinux working could be done in a few days? I am just trying to
understand the effort required to get this working. I basically have a
weekend to complete if it's possible.

Again, thanks for the all help.

-Jason

On Thu, Dec 4, 2014 at 5:36 PM, Jan-Simon Moeller <dl9pf at gmx.de> wrote:

> Am Donnerstag, 4. Dezember 2014, 17:34:02 schrieb Jason Gionta:
> > Hi Jan-Simon,
> >
> > I appreciate the quick reply. I am not currently using the build system
> so
> > I appreciate the insight.
> >
> > So I believe from what you wrote LLVMLinux can emit the IR but does not
> use
> > it for final compilation. Is there LLVM IR->bzImage support?
>
> No, we did not go that far. Back then the student just wanted the IR of the
> single kernel .o files .
> I'm not sure we can do IR->bzImage atm.
> IR->vmlinux maybe, but bzImage has some realmode code with might not go
> through IR to target properly right now.
>
>
> >
> > Thanks again,
> >
> > Jason
> >
> > On Thu, Dec 4, 2014 at 3:50 PM, Jan-Simon Moeller <dl9pf at gmx.de> wrote:
> > > Hi Jason,
> > >
> > > Am Donnerstag, 4. Dezember 2014, 15:10:13 schrieb Jason Gionta:
> > > > Hello all,
> > > >
> > > > I was wondering if someone has looked at or has experience outputting
> > >
> > > LLVM
> > >
> > > > IR of LLVMLinux before linking. I hope to better understand the
> > >
> > > feasibility
> > >
> > > > of deploying IR to perform LTO per machine before final linkage. Does
> > > > anyone have ideas on how much effort would it take to enable in the
> > >
> > > current
> > >
> > > > LLVMLinux build process (basically the linux build system)?
> > > >
> > > > Thanks,
> > >
> > > This works already with the LLVMLinux build system.  Actually we
> compile
> > > every
> > > file twice. One normal compilation and a run for IR .
> > >
> > > cd targets/<yourtarget - eg x86> ; make BITCODE=1
> > >
> > > from make help
> > > * make BITCODE=1          - Output llvm bitcode to *.bc files
> > >
> > > Best,
> > > Jan-Simon
>
>


-- 
Jason Gionta
Cyber Defense Lab
North Carolina State University
jjgionta at ncsu.edu
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