llvm dev - Dec 2009 - [LLVMdev] Compiling a raw binary with llvm/clang

Hey,

The following code creates a raw binary (no ELF or PE.. just raw):

gcc -nostartfiles -c -o hello.o hello.c
ld -o hello1 hello.o --oformat binary

You can try the following code out with it:

void _start()
{
  while(1);
}

The resulting raw binary is 5 bytes.

Now how do you do this in clang/llvm?
Apparently llvm-ld doesn't have a "--oformat binary" option.
Anybody know how to do this with llvm?
-- 
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On 2009-12-17 22:08, LiteHacker wrote:
> Hey,
>
> The following code creates a raw binary (no ELF or PE.. just raw):
>
> gcc -nostartfiles -c -o hello.o hello.c
> ld -o hello1 hello.o --oformat binary
>
> You can try the following code out with it:
>
> void _start()
> {
>   while(1);
> }
>
> The resulting raw binary is 5 bytes.
>   
It is 2.1M here (on x86_64), and 4.3k with -m32 when using gcc 4.4.2.
Apparently it includes the dynamic linker inside it.
> Now how do you do this in clang/llvm?
> Apparently llvm-ld doesn't have a "--oformat binary" option.
> Anybody know how to do this with llvm?
>   
Simple, use ld on the .o files, as you would with gcc.

An example with clang:
$ clang -nostartfiles -c x.c -o x.o
$ ld -o x x.o --oformat binary

Or to get a 32-bit one:
$ /llvm-git/obj/Release/bin/clang -nostartfiles -c x.c -o x.o -m32
$ ld -o x1 x.o --oformat binary -melf_i386

This one is indeed 5 bytes long.

Best regards,
--Edwin

Indeed ld does link it. The reason I am using llvm-ld, is for its unique
functionality.
I intend to link to object files together (created by cling), and link them
with llvm-ld.
The main feature that I am currently interested in is the ability to have
"inline functions" between two object files. This was basically
impossible
with gcc.
Is there any way to make the raw binary with llvm?

Thank you,
Ven


Török Edwin wrote:
> 
> 
> An example with clang:
> $ clang -nostartfiles -c x.c -o x.o
> $ ld -o x x.o --oformat binary
> 
> Or to get a 32-bit one:
> $ /llvm-git/obj/Release/bin/clang -nostartfiles -c x.c -o x.o -m32
> $ ld -o x1 x.o --oformat binary -melf_i386
> 
> This one is indeed 5 bytes long.
> 
> Best regards,
> --Edwin
> 
> 
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