[LLVMdev] llvm-gfortran problems

[Dmitry N. Mikushin]

I see. And what's the purpose for outputting bitcode into *.o and *.a
files? Do you want to perform an LLVM pass on linking step?

2011/9/13 Ashay Rane <ashay.rane at tacc.utexas.edu>:
> Hmm.. I didn't explain the problem completely last time. I am creating a
> drop-in replacement for gcc and gfortran that runs an additional pass on the
> bitcode before generating the native binary. Here's whats happening: If the
> source code compilation process builds a static library (.a archive file), I
> need a means to link the `.a' file statically into the application. So if
> the original statement was:
> gfortran file.o -L somedir -lmylib -o file
> then my modified compilation process would have to deal with file.o and
> libmylib.a to generate the binary `file'. Now, all files essentially contain
> bitcode (file.o and object files inside libmylib.a). So the pseudo-code
> would look like:
> -- QUOTE --
> For all input files passed to compiler:
>     If extension is .o:
>         Use llc to generate .s file
>         Add this filename to some collection
>     Else if extension is .a:
>         Extract contents of this archive
>         Use llc on each file to generate .s file
>         Add each filename to the collection
>     End if
> End for
> Retrieve all `.s' filenames and pass them all to gcc or gfortran
> -- UNQUOTE --
> But the part that deals with `.a' files is a bit ugly. llvm-ld handles the
> archive (.a) files without any manual extraction but I fear that because
> llvm-ld is not a full-featured linker, I might run into a wall because of
> incompatible options between gfortran/gcc and llvm-ld.
> Ashay
>
> On Mon, Sep 12, 2011 at 3:38 PM, Dmitry N. Mikushin <maemarcus at gmail.com>
> wrote:
>>
>> Sorry, at what step do you need archive? llc emits binary, it does not
>> perform any linking, thus it does not need anything except the input
>> bytecode file. Then during linking you can link whatever archives of
>> binaries you want.
>>
>> 2011/9/13 Ashay Rane <ashay.rane at tacc.utexas.edu>:
>> > Thats correct. But using llc becomes a problem when I have archives (.a
>> > files). I could, in theory, extract its contents to a tempdir and then
>> > use
>> > llc and link but just wondering if there is a more elegant solution.
>> > Ashay
>> >
>> > On Mon, Sep 12, 2011 at 3:00 PM, Dmitry N. Mikushin
>> > <maemarcus at gmail.com>
>> > wrote:
>> >>
>> >> Ashay,
>> >>
>> >> If I understand correctly, in hw.o you would have llvm bytecode, while
>> >> linker expects regular object binary. Probably first you need to emit
>> >> asm out of bytecode using llc?
>> >>
>> >> - D.
>> >>
>> >> 2011/9/12 Ashay Rane <ashay.rane at tacc.utexas.edu>:
>> >> > Hello,
>> >> > Sorry for the late reply. Using dragonegg worked well, thanks all!
>> >> > Just as a note... I had to use llvm-ld during the link step because
>> >> > gfortran
>> >> > could not link bitcode. Here's an example of the error shown when
>> >> > using
>> >> > gfortran instead of llvm-ld:
>> >> > $ ${GCC_4_5_0}/bin/gfortran hw.f -c
>> >> > -fplugin=${DRAGONEGG_PLUGIN}/dragonegg.so -o hw.o -flto -emit-llvm -S
>> >> > $ ${LLVM_2_9}/bin/opt -mem2reg hw.o -o hw.o
>> >> > $ ${GCC_4_5_0}/bin/gfortran
>> >> >
>> >> >
>> >> > -fplugin=${DRAGONEGG_PLUGIN}/dragonegg.so ${GCC_4_5_0}/lib64/libgfortran.a
>> >> > hw.o -o hw
>> >> > hw.o: file not recognized: File format not recognized
>> >> > collect2: ld returned 1 exit status
>> >> > $ file hw.o
>> >> > hw.o: data
>> >> > Instead, using llvm-ld:
>> >> > $ ${LLVM_2_9}/bin/llvm-ld -native hw.o -o hw
>> >> > ${GCC_4_5_0}/lib64/libgfortran.a -lm
>> >> > llvm-gcc had the gold plugin. I wonder if there is any equivalent of
>> >> > that
>> >> > for dragonegg to be able to compile bitcode and native object code in
>> >> > a
>> >> > transparent manner.
>> >> > Thanks again!
>> >> > Ashay
>> >> >
>> >> > On Wed, Aug 31, 2011 at 4:29 PM, Anton Korobeynikov
>> >> > <anton at korobeynikov.info> wrote:
>> >> >>
>> >> >> Hello
>> >> >>
>> >> >> > I am not very familiar with Fortran programs. I saw a few programs
>> >> >> > that
>> >> >> > had
>> >> >> > a "MAIN" subroutine defined, some others that did not. Am I
>> >> >> > missing
>> >> >> > something while compiling the code? Is there a different way to
>> >> >> > compile
>> >> >> > bitcode (from Fortran programs) to a native binary?
>> >> >> For Fortran MAIN is indeed something similar to C main, but not
>> >> >> exactly the same.
>> >> >> You have to link the runtime library (libgfortran.a) in order to get
>> >> >> "proper" main, mak sure all stuff is initialized properly, etc.
>> >> >>
>> >> >> --
>> >> >> With best regards, Anton Korobeynikov
>> >> >> Faculty of Mathematics and Mechanics, Saint Petersburg State
>> >> >> University
>> >> >
>> >> >
>> >> > _______________________________________________
>> >> > LLVM Developers mailing list
>> >> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> >> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>> >> >
>> >> >
>> >
>> >
>
>