llvm dev - Jun 2012 - [LLVMdev] What's Going Wrong with GCC 4.6.3 + dragonegg 3.1

Hi all;

Problem: Running a bitcode file produced by llvm-gcc (gcc 4.6.3 + dragonegg
3.1 + llvm 3.1) with lli (Ubuntu 12.04)

*llvm-gcc:*

llvm-gcc -c hello.c -emit-llvm -o hello.bc
lli hello.bc

output:
lli: hello.bc:1:1: error: expected top-level entity
ELF@4(

*clang:*

clang -c hello.c -emit-llvm -o hello.bc
lli hello.bc

output:
hello world

hello.c:
#include <stdio.h>
int main() {
  printf("hello world\n");
  return 0;
}

Any suggestions on how to do it in llvm-gcc?
--
Arnamoy Bhattacharyya
Athabasca Hall 143
Department of Computing Science - University of Alberta
Edmonton, Alberta, Canada, T6G 2E8
587-710-7073
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Arnamoy Bhattacharyya wrote:
> Hi all;
>
> Problem: Running a bitcode file produced by llvm-gcc (gcc 4.6.3 +
> dragonegg 3.1 + llvm 3.1) with lli (Ubuntu 12.04)
>
> /llvm-gcc:/
>
> llvm-gcc -c hello.c -emit-llvm -o hello.bc
> lli hello.bc
>
> output:
> lli: hello.bc:1:1: error: expected top-level entity
> ELF@4(
>
> /clang:/
>
> clang -c hello.c -emit-llvm -o hello.bc
Dragonegg doesn't handle -emit-llvm, and it's being silently eaten by 
gcc (offhand, I think it passes it down to the linker which in turn 
interprets it as meaning that "mit-llvm" will be the name of the entry
point function). Try either -flto or -fplugin-arg-dragonegg-emit-ir to 
produce bitcode.

Nick
> lli hello.bc
>
> output:
> hello world
>
> hello.c:
> #include <stdio.h>
> int main() {
>    printf("hello world\n");
>    return 0;
> }
>
> Any suggestions on how to do it in llvm-gcc?
> --
> Arnamoy Bhattacharyya
> Athabasca Hall 143
> Department of Computing Science - University of Alberta
> Edmonton, Alberta, Canada, T6G 2E8
> 587-710-7073
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On 06/16/2012 08:41 PM, Nick Lewycky wrote:
> Dragonegg doesn't handle -emit-llvm, and it's being silently eaten
by
> gcc (offhand, I think it passes it down to the linker which in turn 
> interprets it as meaning that "mit-llvm" will be the name of the
entry
> point function). Try either -flto or -fplugin-arg-dragonegg-emit-ir to 
> produce bitcode.
At present, this will only work with gcc -S in order to generate LLVM
assembler code (.ll) which can then be compiled to bitcode using
llvm-as. If you use -flto or -fplugin-arg-dragonegg-emit-ir with gcc -c,
gcc will just try to pass LLVM assembler to the system assembler (as),
with predictable results. ;-)

It would really be nice to have gcc -flto -c just work, but I think that
it's not possible right now because gcc needs to be patched up to
support it, right?

Albert

-- 
Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr.Graef at t-online.de, ag at muwiinfa.geschichte.uni-mainz.de
WWW:    http://www.musikinformatik.uni-mainz.de/ag