Hi,
Does any body work on a LLVM backend for Free Pascal? Has anybody experience with LLVM?
Are there licensing issues?
What about the quality of the produced code?
What about compiling speed?
Thoughts?

Thanks, Martin

The IR changes syntax often, so using that will most likely cause version problems. The other option is to use C++ classes directly which apparently is more stable.

I know i386, x86_64 and ARM works pretty good. I don't know about the few others.

Compiling speed is very, very slow :) (when using ir input at least)

Having worked a bit with llvm I don't like the IDE of completely changing the backend of fpc. Mostly because we are then relying on a bunch of C++ programmers to fix bugs and extend the backend in the future.

Regards
Jeppe Johansen

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Martin Schreiber wrote

Hi, Does any body work on a LLVM backend for Free Pascal? Thoughts?

The counterpart of what you want: tries to generate great code at any cost while being maintainable and having a portable code generator.

Do you have experiences with LLVM? Does it actually create great code?

Martin

As far as I know, Jonas has some experience with it;
I'm not sure whether he actually looked at a back-end for it.

Michael.

He did look, because there's a LLVM branch after all :)

Regards,
Sven

Jeppe Græsdal Johansen wrote

Having worked a bit with llvm I don't like the IDE of completely changing the backend of fpc. Mostly because we are then relying on a bunch of C++ programmers to fix bugs and extend the backend in the future.

We would NOT give up the current backends. LLVM would simply be an additional backend.

Regards,
Sven

The author of ExtPascal created this project: llvm-pascal http://code.google.com/p/llvm-pascal/

Marcos Douglas

Please...

Have you actually looked at the code ? It doesn't even read/write units.

Besides actual code, it is doomed to fail in principle:

"The purpose of LLVM-Pascal is to have a similar functionality with up to 4000 lines of code"

A stand-alone, cross-platform, object pascal compiler that produces a working binary in less than 4000 lines of code ? Get real :)

Some things are by definition not simple.

Michael.

Michael,
I don't know anything about LLVM or LLVM-Pascal and no, I did not read any unit...
If even Martin Schreiber has doubts and asked "thoughts" well I just put thoughts on the table. ;-)

Marcos Douglas

No problem.

But presenting it just like that makes people think that it is actually easy or already accomplished to create something like FPC or Delphi.

When in fact it is not, far from it.

So I provide some perspective (OK, not without sarcasm...).

Michael.

All right... hehehe
Well, I think everybody knows that is a huge task to implement... even for somebody of FPC core!

Regards,
Marcos Douglas

None of the FPC team could have done it alone.

It's only possible with the cooperation and help of the community.

All help is welcome. That is why I still try to get Martin to help instead of fork. More people can get more work done.

Michael.

In our previous episode, Martin Schreiber said:

Phonorix had some benchmarks, and generally in gcc came out on top.

I know at least the generated arm code of it.

Does it actually create great code?

I mentioned only the goal of the project.

AFAIK, Embarcadero is doing something like this for a future version of Delphi (to provide an ARM compiler that is rather compatible to FP).

-Michael

Martin Schreiber wrote

Do you have experiences with LLVM? Does it actually create great code?

Lets see what Embarcadero comes up with....

-Michael

Michael Schnell wrote

> Lets see what Embarcadero comes up with....

I wouldn't hold my breath. Based on recent Embarcadero history, the first version would be absolute crap, second version might be beta quality, 3rd version might not even exist (removed from product).

Regards,
- Graeme -