libgccjit questions

[Andrea Corallo]

Daurnimator <quae@daurnimator.com> writes:

> Hi,

Hi!

> I'm looking into using libgccjit as an ahead-of-time compiler to write
> a backend for zig (https://ziglang.org/)
> I've got a few questions I hope you can answer:
>
> What became of cross-compilation? I saw it mentioned as a possible
> roadmap item in
> https://gcc.gnu.org/legacy-ml/jit/2015-q3/msg00086.html)

AFAIK cross compilation is not supported and nothing is going on in that
sense.  I believe this is in line with the idea of libgccjit being
mainly intended for making jitters.

> How can I support inline assembly?

I believe you cannot use inline assembly as we have no specific support
for that and asm and __asm__ are not builtin functions so they can't be
used with gcc_jit_context_get_builtin_function.

> Would it be reasonable to add an API that allows extracting sections
> without writing out to a file and reading it back in?

The elf file is always produced because the assembler is invoked as a
child process, so as of today this cannot happen in memory.

> Alteratively, would it be possible to get a pointer and length to e.g.
> an ELF in memory?
>
> Should distros be packaging libgccjit?
> I noticed that e.g. ArchLinux is not. Possibly because it is
> documented as "experimental"; possibly because it requires building
> gcc with --enable-host-shared ?

Most distros are already packing libgccjit, even if the quality of the
package may vary.

> What is the license situation with libgccjit; is it GPL? LGPL? what
> does this mean for code that uses libgccjit?

AFAIU libgccjit is part of GCC and this is released under the GNU
General Public License.

> Thanks,
> Daurnimator

Bests

  Andrea
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