llvm dev - Oct 2015 - ELF object writing from assembly file

Hi all,

I have implemented AsmParser, CodeEmitter, and ELF object writing.
AsmParser and CodeEmitter are tested and working fine, but I would like to
see ELF objects build out of a parsed asm file. Is that possible?

I tried this commands, but it didn't work corrctly:

*llvm-mc -filetype=obj -arch=test file.s -o=a.o*

and I think after an obj file is built, I should use this command but I am
not sure!

*llvm-objdump -arch=test a.o*

Cheers,
ES
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(corrector) I think for reading obj file it should be:
*llvm-readobj -arch=test  a.o*

On Tue, Oct 13, 2015 at 11:19 AM, Sky Flyer <skylake007 at googlemail.com>
wrote:
> Hi all,
>
> I have implemented AsmParser, CodeEmitter, and ELF object writing.
> AsmParser and CodeEmitter are tested and working fine, but I would like to
> see ELF objects build out of a parsed asm file. Is that possible?
>
> I tried this commands, but it didn't work corrctly:
>
> *llvm-mc -filetype=obj -arch=test file.s -o=a.o*
>
> and I think after an obj file is built, I should use this command but I am
> not sure!
>
> *llvm-objdump -arch=test a.o*
>
> Cheers,
> ES
>
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On 13 October 2015 at 02:19, Sky Flyer via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> I tried this commands, but it didn't work corrctly:
>
> llvm-mc -filetype=obj -arch=test file.s -o=a.o
That looks right to me ("-triple test-elf" might be more robust and
work if you're coding on OS X or Windows).
> and I think after an obj file is built, I should use this command but I am
> not sure!
>
> llvm-objdump -arch=test a.o
Either llvm-objdump or llvm-readobj will work. llvm-readobj tends to
produce lower level information, while llvm-objdump is more
user-friendly. They ought to mostly work on the generic information
without changes.

If you want "-d" (disassemble) to work, you're going to have to
implement a Disassembler in your target too.

Tim.

Thanks a lot Tim.

I am getting an error which says: "LLVM ERROR: unable to write nop sequence
of 0 bytes"
Is there any way that I can print out the Obj code (I mean bitstream
representation of the assembly code which is going to be placed in the ELF
file), before making any ELF file?

Cheers,
ES

On Tue, Oct 13, 2015 at 3:02 PM, Tim Northover <t.p.northover at
gmail.com>
wrote:
> On 13 October 2015 at 02:19, Sky Flyer via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > I tried this commands, but it didn't work corrctly:
> >
> > llvm-mc -filetype=obj -arch=test file.s -o=a.o
>
> That looks right to me ("-triple test-elf" might be more robust
and
> work if you're coding on OS X or Windows).
>
> > and I think after an obj file is built, I should use this command but
I
> am
> > not sure!
> >
> > llvm-objdump -arch=test a.o
>
> Either llvm-objdump or llvm-readobj will work. llvm-readobj tends to
> produce lower level information, while llvm-objdump is more
> user-friendly. They ought to mostly work on the generic information
> without changes.
>
> If you want "-d" (disassemble) to work, you're going to have
to
> implement a Disassembler in your target too.
>
> Tim.
>
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