5 ms·

Aro: A C compiler written in Zig

150 points by frankjr 5y ago

svnpenn 5y ago
I dont get it, doesnt the Zig project itself already do this?
- diegocg 5y ago
  > Future plans for the project include making it the C backend of Zig's translate-c feature and making it an optional C frontend for the self-hosted Zig compiler.
- mitchellh 5y ago
  The Zig project is able to compile C because it embeds LLVM. This is different and has different use cases, imo. Example: this may be a good alternative frontend for C compilation in Zig under specific scenarios.
  - dnautics 5y ago
    I think incremental compilation and hotswapping are some of those use cases, but I could be wrong about that (I'm not entirely sure if/why LLVM can't do it)
    - pjmlp 5y ago
      It can partially do that already, thanks to CERN and others collaborating on its C++ JIT. 2021 LLVM Developers Meeting “Enabling Interactive C++ with Clang” https://www.youtube.com/watch?v=33ncbIQoa4c https://www.youtube.com/watch?v=33ncbIQoa4c Currently the best developer experience for hot code reload for C++ is Visual C++ 2022.
      - gavinray 5y ago
        It would be fair to say this is mostly due in particular to the work of Vassil Vassilev and Axel Naumann rather than all of CERN. If you're interested, they have monthly meetups open to the public, with fantastic speakers and presentations: https://compiler-research.org/meetings/ https://compiler-research.org/meetings/
        pjmlp 5y ago
        Sure, I also didn't meant it was all of CERN. Back in my days, ROOT wasn't getting much love on my department, we were focused more in Python bindings.
- wyldfire 5y ago
  Yes, but thank goodness there's no quota.
- wchar_t 5y ago
  I believe it calls into Clang/LLVM to do so.
- klyrs 5y ago
  There's a pretty good chance that "A C compiler written in ___" will be well-received here, regardless of ___.
  - 3a2d29 5y ago
    To add to this, I feel like half of the good github projects are doing something just because you can.
    - egeozcan 5y ago
      Which, to be frank, is a wonderful thing.
    - vidarh 5y ago
      In this case, though, it seems like embeddable C compilers as means to support integration of C code into other languages in better ways is becoming a trend.
- WalterBright 5y ago
  The dmd D compiler now has an embedded C compiler, written in D. The purpose is so D code can read C declarations. It doesn't use clang.
  - fayten 5y ago
    Does this mean you can directly import C headers in D?
    - WalterBright 5y ago
      yes
      - oshiar53-0 5y ago
        How about static inline functions?
        WalterBright 5y ago
        yes
      - fayten 5y ago
        Well well well, I guess it's time to brush off the ol' dmd.
  - MaxBarraclough 5y ago
    For contrast, gforth (a prominent Forth interpreter, by Forth standards) generates+compiles+links binding code in C, at runtime, using the ordinary C toolchain. [0][1][2] A bit 'out there' you may say, but on the plus side this approach enables handling header files and tidily expressing bindings without the need to implement their own C parser. [2] [0] GitHub mirror: https://github.com/forthy42/gforth/blob/dda77d851ddeb80ca849ee554b29ac68fb680a87/libcc.fs#L22 https://github.com/forthy42/gforth/blob/dda77d851ddeb80ca849... [1] The official host: https://git.savannah.gnu.org/cgit/gforth.git/tree/libcc.fs https://git.savannah.gnu.org/cgit/gforth.git/tree/libcc.fs [2] https://rosettacode.org/wiki/Call_a_foreign-language_function#Forth https://rosettacode.org/wiki/Call_a_foreign-language_functio...
bjconlan 5y ago
Andrew Kelley literally did a twitch vid this morning covering something inline with the goals of this project... The zig community seems pretty good so I'm sure everyone's efforts will be celebrated (as all community work should)
tiehuis 5y ago
There is a recent draft PR [1] to merge this into the zig compiler itself. LLVM is being placed as a an optional component in the future [2]. Using arocc to fill this gap would mean that seamless C compilation could still be done, without LLVM being involved. [1] https://github.com/ziglang/zig/pull/10795 https://github.com/ziglang/zig/pull/10795 [2] https://kristoff.it/blog/zig-new-relationship-llvm/ https://kristoff.it/blog/zig-new-relationship-llvm/
AndyKelley 5y ago
Oh wow I had no idea this was just casually sitting on HN front page while I was streaming live coding of adding this to the Zig compiler! Here's the recording: https://vimeo.com/673819867 https://vimeo.com/673819867 I see WalterBright down there in the comments. Hi! His talk at Handmade Seattle about adding a C compiler to D was amusing and informative: https://media.handmade-seattle.com/importc/ https://media.handmade-seattle.com/importc/ Some interesting differences between the two approaches: * D ImportC relies on an external preprocessor, while Aro does preprocessing. * D ImportC lowers to D AST, while Aro lowers Zig AIR. This tweet has an infographic to help you get an idea of where AIR is in the Zig compiler pipeline: https://twitter.com/andy_kelley/status/1457800302946492418 https://twitter.com/andy_kelley/status/1457800302946492418 * D ImportC is shipped, while Aro as a C frontend in Zig is an [unfinished branch](https://github.com/ziglang/zig/pull/10795 https://github.com/ziglang/zig/pull/10795) It's been really exciting watching Vexu and ehaas (and other contributors) working on Aro. Looks like there's some confusion as to why this exists when Zig already uses libclang to compile C code. The main reasons are: * Improved `@cImport`/translate-c functionality, especially with regards to translation of macros. Vexu and ehaas are the main contributors of Zig's C translation implementation. * Ability to bootstrap a lean Zig binary that does not depend on LLVM, and yet is still able to compile C code and use the `@cImport` language feature to translate C code. * Ability to more tightly integrate with Zig's linker, bringing some incremental compilation abilities to C. Due to language limitations it can never be as good as Zig but it can still be improved over other C compilers. * Ability to compile C code to targets that LLVM does not support. Zig plans to support a wider target range than LLVM.
- 2pEXgD0fZ5cF 5y ago
  Hey! Nice to see you posting here. I've been keeping an eye on Zig for a while now because everything around it just looks pretty amazing! 2 questions: - What are some books or resources you would recommend to get into (practical) low level programming with the goal of writing better Zig code? I know my basic self defense in C, and from a gut feeling I'd say C resources carry over the most but I'd be interested in how you see things and which resources you like or see a decent carryover in. - I personally enjoy reading the Zig source code to learn the language. But what is something you'd like to see arise to improve the teaching of Zig in the future and once things get closer to 1.0?
amelius 5y ago
> Ability to compile C code to targets that LLVM does not support. Zig plans to support a wider target range than LLVM. Wouldn't it be way more beneficial to extend LLVM instead?
- jpgvm 5y ago
  One does not simply add a target to LLVM. If it was trivial I can assure you the Rust folk would have already been at it.

150 points by frankjr 5y ago

svnpenn 5y ago

I dont get it, doesnt the Zig project itself already do this?

diegocg 5y ago
> Future plans for the project include making it the C backend of Zig's translate-c feature and making it an optional C frontend for the self-hosted Zig compiler.
mitchellh 5y ago
The Zig project is able to compile C because it embeds LLVM. This is different and has different use cases, imo. Example: this may be a good alternative frontend for C compilation in Zig under specific scenarios.
- dnautics 5y ago
  I think incremental compilation and hotswapping are some of those use cases, but I could be wrong about that (I'm not entirely sure if/why LLVM can't do it)
  - pjmlp 5y ago
    It can partially do that already, thanks to CERN and others collaborating on its C++ JIT. 2021 LLVM Developers Meeting “Enabling Interactive C++ with Clang” https://www.youtube.com/watch?v=33ncbIQoa4c https://www.youtube.com/watch?v=33ncbIQoa4c Currently the best developer experience for hot code reload for C++ is Visual C++ 2022.
    - gavinray 5y ago
      It would be fair to say this is mostly due in particular to the work of Vassil Vassilev and Axel Naumann rather than all of CERN. If you're interested, they have monthly meetups open to the public, with fantastic speakers and presentations: https://compiler-research.org/meetings/ https://compiler-research.org/meetings/
      - pjmlp 5y ago
        Sure, I also didn't meant it was all of CERN. Back in my days, ROOT wasn't getting much love on my department, we were focused more in Python bindings.
wyldfire 5y ago
Yes, but thank goodness there's no quota.
wchar_t 5y ago
I believe it calls into Clang/LLVM to do so.
klyrs 5y ago
There's a pretty good chance that "A C compiler written in ___" will be well-received here, regardless of ___.
- 3a2d29 5y ago
  To add to this, I feel like half of the good github projects are doing something just because you can.
  - egeozcan 5y ago
    Which, to be frank, is a wonderful thing.
  - vidarh 5y ago
    In this case, though, it seems like embeddable C compilers as means to support integration of C code into other languages in better ways is becoming a trend.
WalterBright 5y ago
The dmd D compiler now has an embedded C compiler, written in D. The purpose is so D code can read C declarations. It doesn't use clang.
- fayten 5y ago
  Does this mean you can directly import C headers in D?
  - WalterBright 5y ago
    yes
    - oshiar53-0 5y ago
      How about static inline functions?
      - WalterBright 5y ago
        yes
    - fayten 5y ago
      Well well well, I guess it's time to brush off the ol' dmd.
- MaxBarraclough 5y ago
  For contrast, gforth (a prominent Forth interpreter, by Forth standards) generates+compiles+links binding code in C, at runtime, using the ordinary C toolchain. [0][1][2] A bit 'out there' you may say, but on the plus side this approach enables handling header files and tidily expressing bindings without the need to implement their own C parser. [2] [0] GitHub mirror: https://github.com/forthy42/gforth/blob/dda77d851ddeb80ca849ee554b29ac68fb680a87/libcc.fs#L22 https://github.com/forthy42/gforth/blob/dda77d851ddeb80ca849... [1] The official host: https://git.savannah.gnu.org/cgit/gforth.git/tree/libcc.fs https://git.savannah.gnu.org/cgit/gforth.git/tree/libcc.fs [2] https://rosettacode.org/wiki/Call_a_foreign-language_function#Forth https://rosettacode.org/wiki/Call_a_foreign-language_functio...

bjconlan 5y ago

Andrew Kelley literally did a twitch vid this morning covering something inline with the goals of this project... The zig community seems pretty good so I'm sure everyone's efforts will be celebrated (as all community work should)

tiehuis 5y ago

There is a recent draft PR [1] to merge this into the zig compiler itself. LLVM is being placed as a an optional component in the future [2]. Using arocc to fill this gap would mean that seamless C compilation could still be done, without LLVM being involved. [1] https://github.com/ziglang/zig/pull/10795 https://github.com/ziglang/zig/pull/10795 [2] https://kristoff.it/blog/zig-new-relationship-llvm/ https://kristoff.it/blog/zig-new-relationship-llvm/

AndyKelley 5y ago

Oh wow I had no idea this was just casually sitting on HN front page while I was streaming live coding of adding this to the Zig compiler! Here's the recording: https://vimeo.com/673819867 https://vimeo.com/673819867 I see WalterBright down there in the comments. Hi! His talk at Handmade Seattle about adding a C compiler to D was amusing and informative: https://media.handmade-seattle.com/importc/ https://media.handmade-seattle.com/importc/ Some interesting differences between the two approaches: * D ImportC relies on an external preprocessor, while Aro does preprocessing. * D ImportC lowers to D AST, while Aro lowers Zig AIR. This tweet has an infographic to help you get an idea of where AIR is in the Zig compiler pipeline: https://twitter.com/andy_kelley/status/1457800302946492418 https://twitter.com/andy_kelley/status/1457800302946492418 * D ImportC is shipped, while Aro as a C frontend in Zig is an [unfinished branch](https://github.com/ziglang/zig/pull/10795 https://github.com/ziglang/zig/pull/10795) It's been really exciting watching Vexu and ehaas (and other contributors) working on Aro. Looks like there's some confusion as to why this exists when Zig already uses libclang to compile C code. The main reasons are: * Improved `@cImport`/translate-c functionality, especially with regards to translation of macros. Vexu and ehaas are the main contributors of Zig's C translation implementation. * Ability to bootstrap a lean Zig binary that does not depend on LLVM, and yet is still able to compile C code and use the `@cImport` language feature to translate C code. * Ability to more tightly integrate with Zig's linker, bringing some incremental compilation abilities to C. Due to language limitations it can never be as good as Zig but it can still be improved over other C compilers. * Ability to compile C code to targets that LLVM does not support. Zig plans to support a wider target range than LLVM.

2pEXgD0fZ5cF 5y ago
Hey! Nice to see you posting here. I've been keeping an eye on Zig for a while now because everything around it just looks pretty amazing! 2 questions: - What are some books or resources you would recommend to get into (practical) low level programming with the goal of writing better Zig code? I know my basic self defense in C, and from a gut feeling I'd say C resources carry over the most but I'd be interested in how you see things and which resources you like or see a decent carryover in. - I personally enjoy reading the Zig source code to learn the language. But what is something you'd like to see arise to improve the teaching of Zig in the future and once things get closer to 1.0?

amelius 5y ago

> Ability to compile C code to targets that LLVM does not support. Zig plans to support a wider target range than LLVM. Wouldn't it be way more beneficial to extend LLVM instead?

jpgvm 5y ago
One does not simply add a target to LLVM. If it was trivial I can assure you the Rust folk would have already been at it.