Re: DragonEgg has been revived

["Dan'l Miller" <optikos@verizon.net>]

On Tuesday, May 22, 2018 at 3:17:11 PM UTC-5, Dan'l Miller wrote:
> On Tuesday, May 22, 2018 at 2:40:24 PM UTC-5, Shark8 wrote:
> > On Tuesday, May 22, 2018 at 6:29:10 AM UTC-6, Simon Clubley wrote:
> > > 
> > > What I would like to see is an Ada compiler that can generate code
> > > for a wide range of targets without any GPL restrictions on the
> > > generated code.
> > 
> > I'm getting ready to restart work on Byron. I figure that perhaps an Implementation Manual/Design Document would help explain the design underneath it and welcome new contributors. 
> > 
> > > 
> > > I'm not really bothered how that happens but LLVM seems like an
> > > interesting option.
> > 
> > I have mixed feelings on LLVM -- it would be nice to grab all the targets for it, but I also think it's a stupid
> > idea to build the compiler specifically for it.
> 
> Writing a compiler “specifically for” LLVM?  I thought that the whole premise of Byron was to write an Ada compiler for multiple back-ends:
> 1) libFirm:  https://pp.ipd.kit.edu/firm
> 2) LLVM
> 3) GCC
> 4) Graal for JVM:  http://www.graalvm.org
> 5) CLR for .NET & Mono
> and so forth.
> 
> Compared to Byron's laudable long-term clean-room-design goals, my GELI proposal* for an LLVM-backended GNAT is an interim stop-gap, focusing only on likely-not-clean-room generation of LLVM bitcode IR within a single GPLv3 GNAT executable, causing only ISAs' machine-code (not the IR) to be generated by LLVM-embedded-within-GNAT.
> 
> * described in a prior reply above
> 
> > Yeah; that's one of the big problems Byron [Ada 2012 in Ada 2012] is intended to address; the other big
> > one is to escape the stupid morass of licensing issues.
> 
> What is so bad about GPLv3 with Runtime Exception …
> 
> 1) … unless a person really really wants to re-work GCC-emitted machine code as lifted to LLVM bitcode IR via, say, McSema as not-GPLv3ed derivative works, needing disclosure of all source code?**
> or
> 
> 2) … unless a person really really wants to write LLVM bitcode IR out to a file to execute it on Sulong/GraalVM as not-GPLv3ed derivative works, needing disclosure of all source code?**
> or
> 
> 3) Can anyone think of any other precise downsides of GPLv3 •with• Runtime Exception?

I just thought of another one:

3) … unless a person really really wants to write LLVM bitcode IR out to a file to have Polly grind on it with all sorts of advanced optimizations.

Polly and GraalVM of course beget doing to them what was described above for LLVM:

H) Import the entirety of Polly within the GCC repository for compilation (along with the entirety of LLVM) into a single GNAT executable, so that LLVM bitcode IR is never emitted as a file by GNAT just to utilize Polly's polyhedral optimizations with GELI->LLVM.

H.a) Add all the command-line options for Polly to GNAT.

I) Import the entirety of GraalVM within the GCC repository for compilation into a single GNAT executable, so that LLVM bitcode IR is never emitted as a file by GNAT just to utilize GELI->LLVM->GraalVM's Sulong & Polyglot.

I.a) Add all the command-line options for GraalVM to GNAT.