[fpc-devel] LLVM Backend?

Samuel Crow samuraileumas at yahoo.com
Thu Nov 12 18:15:17 CET 2009

Hi Jonas,

----- Original Message ----
> From: Jonas Maebe <jonas.maebe at elis.ugent.be>
> To: FPC developers' list <fpc-devel at lists.freepascal.org>
> Sent: Thu, November 12, 2009 7:48:58 AM
> Subject: Re: [fpc-devel] LLVM Backend?
> It does make a difference. Unfortunately. While working on a patch to add 
> Borland fastcall support to GDB, I discovered that there's a bug in our 
> implementation of Borland fastcall on Mac OS X (although I'm still not sure 
> why). I'll try to fix it tonight and create a test file that you can use.


> > Also, as part of the Mattathias BASIC project, our team leader has almost 
> completed the LLVM-PEG utility for implementing parsing expression grammars in 
> LLVM Assembly.  If I end up continuing the work I started on a new LLVM-FPC 
> parser I'll be using that as my tool of choice and implementing the code 
> sections with support routines from LLVM and Clang. (I won't have the liberty of 
> using Clang's libraries in the BASIC compiler since BASIC requires a two-pass 
> compilation process.)
> That's quite an undertaking!

LLVM does most of the work with its support routines but I expect that once we get the core language support in (including the ability to extend the language), users will help with writing a few extensions themselves.

> > I hope your workload permits you to work on the function calling mechenism 
> soon.  Thanks for your advice.
> Even once this is finished, how do you propose we pass type information from FPC 
> to LLVM libraries? Via strings in LLVM assembler format? (since I've already 
> written that code) Or another way?

There are classes to create any type documented at http://llvm.org/docs/ProgrammersManual.html#Type .  As of the current 2.6 release there are now more extensive C bindings included with LLVM than were previously available.  Once I get the trunk downloaded I'll see about a link to the actual documentation on how to use those C bindings.

Thanks for your help,



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