[LLVMdev] LLVM Newb: Getting started

[Wolfgang Draxinger]

Am Freitag, 24. November 2006 03:00 schrieb Reid Spencer:

> If you're making your own front end, you probably won't need it :)

Well, I wanted to play around with it, so see, how my older programs 
perform with it.

So far I managed to get some programs running by folowing scheme:

for src in $infiles; do
llvm-gcc -o $src.bc -c $src ;
opt -f -o $src.bc.opt $src.bc ;
llc -f $src.bc.opt ;
gcc -c $src.bc.opt.s ;
done

gcc -o $name *.o

However until now I always had to compile the source file with the 
main function directly with gcc, so that the __main function (to 
initialize the globals and static constructors) gets created. 

I did not manage to make llvm-gcc create __main.

> If you can create platform independent code from D, then you should
> be able to just use the LLVM bytecode representation.

D itself is platform independent, but since D is also aimed at system 
programming it has an inline asembler. However one can supply 
different kinds of assembler through conditional comilation, so the 
following would be completely valid:

void foo(){
    version(x86) {
        asm {
/* x86 assembler */
        }
    } else version(llvm) {
        asm {
/* llvm assembler */
        }
    } else {
/* plain D implementation */
    }
}

<http://www.digitalmars.com/d/iasm.html>
<http://www.digitalmars.com/d/version.html>

Any ideas, how this could be integrated with LLVM? The IMHO most naive 
approach would be to add labels where the asm begins and ends. Then 
the plattform dependent assembler being parted from the code llvm 
gets to see and being processed by an external assembler into object 
code. Later in the process the linker then reinserts the assembler 
object code.

-- 
Wolfgang Draxinger
lead programmer - DARKSTARgames

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