[LLVMdev] DragonEgg3.3 support for gcc cross compilers

Tue Oct 28 11:13:49 PDT 2014

What does "file /path/to/tilera-gcc48/bin/tile-gcc" and "file
/path/to/dragonegg.so" report?

On Tue, Oct 28, 2014 at 9:11 PM, Ajay Panyala <ajay.panyala at gmail.com> wrote:
> No. The gcc cross compiler being used (tilera-gcc) is indeed 64-bit.
>
> Thanks
>
> On Tue, Oct 28, 2014 at 11:01 AM, Anton Korobeynikov
> <anton at korobeynikov.info> wrote:
>>
>> Looks like your gcc is 32-bit and you're trying to load 64-bit plugin.
>>
>> On Tue, Oct 28, 2014 at 8:27 PM, Ajay Panyala <ajay.panyala at gmail.com>
>> wrote:
>> > Hi Brian,
>> >
>> > Thanks for sharing your experience with dragonegg.
>> > I would like to use tilera-gcc as the compiler driver. native gcc would
>> > not
>> > be able to
>> > handle things like tilera specific intrinsics in the source code.
>> >
>> > I built dragonegg using
>> >
>> > GCC=/path/to/tilera-gcc48/bin/tile-gcc
>> > LLVM_CONFIG=/path/to/tilera-llvm/bin/tilegx-llvm-config make
>> >
>> > and also tried only emitting the IR
>> >
>> >    /path/to/tilera-gcc48/bin/tile-gcc -fplugin=/path/to/dragonegg.so
>> > -fplugin-arg-dragonegg-emit-ir -S -o hello.ll hello.c
>> >
>> > (and still get the error: cannot load plugin dragonegg.so: wrong ELF
>> > class:
>> > ELFCLASS64 )
>> >
>> > - Ajay
>> >
>> > On Mon, Oct 27, 2014 at 9:39 PM, Brian Faull <bfaull at cog-e.com> wrote:
>> >>
>> >> Hello,
>> >>
>> >> There may be plenty more experienced experts on DragonEgg (and
>> >> hopefully
>> >> they'll correct me if I'm wrong), but I figured I'd chime in with my
>> >> brief
>> >> experience to start. I have messed with this a bit, and DragonEgg has
>> >> worked
>> >> for my experiments.  Your configuration has many things that are
>> >> different
>> >> than mine; however, I think you might simply have the cross-compilers
>> >> crossed backward; I think you want to use your native gcc as
>> >> compiler-driver; pass dragonegg.so to your native-gcc rather than
>> >> tilera-gcc. I think you may simply need to do the following:
>> >>
>> >> 1- Build DragonEgg using your system compiler (or gcc 4.6.4 as
>> >> recommended
>> >> on dragonegg.llvm.org); when doing `make`, point explicitly at your
>> >> *build*
>> >> (x86_64) GCC of choice, and against your *target* (tilera)
>> >> `llvm-config`.
>> >> 2- use your x86_64 compiler-driver as front-end, which due to the magic
>> >> of
>> >> DragonEgg and llvm-config will use your target LLVM backend.
>> >>
>> >> Or it could be really late and I'm not thinking straight. :)
>> >>
>> >> More detail:
>> >> I had to set a few non-obvious (to me) things in the build and use
>> >> process, so I'll reflect them here for you and/or posterity.  You will
>> >> need
>> >> all three components though: LLVM backend for your architecture
>> >> (tilera)
>> >> I'd suggest a few things to try, in order for you to find a
>> >> configuration
>> >> that works for you:
>> >>
>> >> * Sounds like you're on x86_64 / AMD64.  I'd suggest to start with
>> >> building the simplest configuration: using your system compiler to
>> >> build
>> >> everything for your system native architecture, and this will be the
>> >> easiest
>> >> configuration to debug.
>> >>
>> >> * According to the dragonegg.llvm.org web site, DragonEgg works best
>> >> with
>> >> GCC 4.6.  You may wish to try that (I recommend looking at
>> >> http://gcc.gnu.org/gcc-4.6/ for GCC 4.6.4, which is the latest release
>> >> of
>> >> that version).  I don't know exactly why this version is said to work
>> >> best;
>> >> perhaps the DragonEgg site is simply stale.  I bootstrapped a clean,
>> >> native
>> >> version of 4.6.4 without much headache.
>> >>
>> >> * Since I wanted to get DragonEgg built to work with GCC4.6.4, I built
>> >> DragonEgg with GCC4.6.4.  IIRC, the DragonEgg makefile wants you to
>> >> specify
>> >> the compiler as GCC=... rather than CC=... but it looks like it should
>> >> eat
>> >> both.  Also, I read somewhere that LLVM3.3's llvm-config had some
>> >> behavior
>> >> that argues with DragonEgg.  Contrary to best practice "build outside
>> >> the
>> >> source tree" so as to prevent polluting of the source tree, I saw a
>> >> recommendation to build *within* the source tree, so I rolled back and
>> >> built
>> >> LLVM3.3 *in the source tree* (GASP!) for native (x86_64). In sum, to
>> >> build
>> >> DragonEgg I used something like
>> >>    GCC=/path/to/gcc464/bin/gcc
>> >> LLVM_CONFIG=/path/to/llvm-3.3.src-x86_64/prefix/bin/llvm-config make
>> >>
>> >> * Then to use this shiny new .so, I started by going only up to the
>> >> point
>> >> of emitting LLVM IR so as not to confuse the situation with further
>> >> architecture-specific compilation/assembly:
>> >>    /path/to/gcc464/bin/gcc -fplugin=/path/to/dragonegg.so
>> >> -fplugin-arg-dragonegg-emit-ir -S -o hello.ll hello.c
>> >> I also chose to specify the full path of dragonegg.so, so I didn't have
>> >> to
>> >> be concerned with library paths.
>> >>
>> >> Then you should be able to manually use your backend (llvm33/bin/llc,
>> >> assembler, etc.) to generate an architecture-specific object.  Once
>> >> you've
>> >> got all those components, you should be able to get everything
>> >> integrated
>> >> with just one gcc compiler-driver invocation.
>> >>
>> >> HTH,
>> >> Brian
>> >>
>> >>
>> >>
>> >>
>> >> On Oct 27, 2014, at 11:53 PM, Ajay Panyala <ajay.panyala at gmail.com>
>> >> wrote:
>> >>
>> >> I am using a gcc (v 4.8.2) cross compiler for the tilera architecture.
>> >> There is an LLVM (v 3.3) cross compiler available for tilera
>> >> (http://tilera.github.io/llvm),
>> >> but the frontend only has partial support for certain tilera intrinsics
>> >> and no OpenMP support.
>> >>
>> >> Hence, I have decided to use DragonEgg (v 3.3) to resolve this. I was
>> >> able
>> >> to build
>> >> DragonEgg, but when I pass the command line argument
>> >> -fplugin=dragonegg.so
>> >> when compiling with the tilera-gcc I get the error
>> >>
>> >> cannot load dragonegg.so: wrong ELF class: ELFCLASS64
>> >>
>> >> i.e. the tilera-gcc does not accept the x86 shared library object
>> >> dragonegg.so
>> >>
>> >> The dragonegg sources were built using the x86 GCC, but the plugin
>> >> was built to load into the tilera gcc.
>> >>
>> >> Could someone please point out what I am missing here.
>> >>
>> >> Thanks
>> >> Ajay
>> >> _______________________________________________
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>> >>
>> >>
>> >
>> >
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>> >
>>
>>
>>
>> --
>> With best regards, Anton Korobeynikov
>> Faculty of Mathematics and Mechanics, Saint Petersburg State University
>
>

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University