4 ms·

I find it shocking that 20 years after LLVM was created, gcc still hasn't moved towards modularization of codegen.

by MangoToupe 10mo ago

ayende 10mo ago
Isn't that very much intentional on the part of GCC?
- demurgos 10mo ago
  It is intentional to avoid non-free projects from building on top of gcc components. I am not familiar enough with gcc to know how it impacts out-of-tree free projects or internal development. The decision was taken a long time ago, it may be worth revisiting it.
  - janc_ 10mo ago
    Over the years several frontends for languages that used to be out-of-tree for years have been integrated. So both working in-tree & outside are definitely possible.
- colejohnson66 10mo ago
  Somewhat. Stallman claims to have tried to make it modular,[0] but also that he wants to avoid "misuse of [the] front ends".[1] The idea is that you should link the front and back ends, to prevent out-of-process GPL runarounds. But because of that, the mingling of the front and back ends ended up winning out over attempts to stay modular. [0]: https://lists.gnu.org/archive/html/emacs-devel/2015-02/msg00693.html https://lists.gnu.org/archive/html/emacs-devel/2015-02/msg00... [1]: https://lists.gnu.org/archive/html/emacs-devel/2015-01/msg00015.html https://lists.gnu.org/archive/html/emacs-devel/2015-01/msg00...
  - phkahler 10mo ago
    >> The idea is that you should link the front and back ends, to prevent out-of-process GPL runarounds. Valid points, but also the reason people wanting to create a more modular compiler created LLVM under a different license - the ultimate GPL runaround. OTOH now we have two big and useful compilers!
  - colechristensen 10mo ago
    Good lord Stallman is such a zealot and hypocrite. It's not open vs. closed it's mine vs. yours and he's openly declaring that he's nerfing software in order to prevent people from using it in a way he doesn't like. And refusing to talk about it in public because normal people hate that shit "misunderstanding" him. --- From the post: I let this drop back in March -- please forgive me. > Maybe that's the issue for GCC, but for Emacs the issue is to get detailed > info out of GCC, which is a different problem. My understanding is that > you're opposed to GCC providing this useful info because that info would > need to be complete enough to be usable as input to a proprietary > compiler backend. My hope is that we can work out a kind of "detailed output" that is enough for what Emacs wants, but not enough for misuse of GCC front ends. I don't want to discuss the details on the list, because I think that would mean 50 messages of misunderstanding and tangents for each message that makes progress. Instead, is there anyone here who would like to work on this in detail?
    - bigfishrunning 10mo ago
      He should just re-license GCC to close whatever perceived loophole, instead of actively making GCC more difficult to work with (for everyone!). RMS has done so much good, but he's so far from an ideal figure.
      - tovej 10mo ago
        How in the world would you relicense GCC
        colechristensen 10mo ago
        Most contributions are required to assign copyright to the FSF, so it's not actually particularly open. If the FSF is the sole copyright owner they're free to relicense it however they please, if no one else has any controlling interest of the copyright, the GPL doesn't restrict you from relicensing something you're the sole owner of (and it's doubtful there's a legal mechanism to give away rights to something you continue to own) Again, the FSF under Stallman isn't about freedom it's about control.
  - giancarlostoro 10mo ago
    That sounds like Stallman wants proprietary OSS ;) If you're going to make it hard for anyone anywhere to integrate with your open source tooling for fear of commercial projects abusing them and not ever sharing their changes, why even use the GPL license?
    - dhosek 10mo ago
      This is a big part of why I’ve always eschewed GPL.
  - Croak 10mo ago
    When gcc was built most compilers were proprietary. Stallman wanted a free compiler and to keep it free. The GPL license is more restrictive, but it's philosophy is clear. At the end of the day the code's writer can choose if and how people are allowed to use it. You don't have to use it, you can use something else or build you own. And maybe, just maybe Linux is thriving while Windows is dying because in the Linux ecosystem everybody works together and shares, while in Windows everybody helps together paying for Satya Nadellas next yacht.
    - Y_Y 10mo ago
      > At the end of the day the code's writer can choose if and how people are allowed to use it. If it's free software then I can modify and use it as I please. What's limited is redistributing the modified code (and offering a service to users over a network for Afferro). https://www.gnu.org/philosophy/free-sw.en.html#fs-definition https://www.gnu.org/philosophy/free-sw.en.html#fs-definition
- wahern 10mo ago
  Not anymore. Modularization is somewhat tangential, but for awhile Stallman did actively oppose rearchitecting GCC to better support non-free plugins and front-ends. But Stallman lost that battle years ago. AFAIU, the current state of GCC is the result of intentional technical choices (certain kinds of decoupling not as beneficial as people might think--Rust has often been stymied by lack of features in LLVM, i.e. defacto (semantic?) coupling), works in progress (decoupling ongoing), or lack of time or wherewithal to commit to certain major changes (decoupling too onerous).
  - torginus 10mo ago
    Personally, I think when you are making bad technical decisions in service of legal goals (making it harder to circumvent the GPL), that's a sure sign that you made a wrong turn somewhere.
    - 1718627440 10mo ago
      Why? When your goal is to have free software, having non-free software with better architecture won't suit you.
      - bigstrat2003 10mo ago
        I would describe this more as "trying to prevent others from having non-free software if they wish to", which is a lot more questionable imo.
        LeFantome 10mo ago
        Some in the Free Software community do not believe that making it harder to collaborate will reduce the amount of software created. For them, you are going to get the software and the choice is just “free” or not. And they imagine that permissively license code bases get “taken” and so copyleft licenses result in more code for “the community”. I happen to believe that barriers to collaboration results in less software for everybody. I look at Clang and GCC and come away thinking that Clang is the better model because it results in more innovation and more software that I can enjoy. Others wonder why I am so naive and say that collaborating on Clang is only for corporate shills and apologists. You can have whatever opinion you want. I do not care about the politics. I just want more Open Source software. I mean, so do the others guys I imagine but they don’t always seem to fact check their theories. We disagree about which model results in more software I can use.
pjmlp 10mo ago
LLVM wasn't the first modularization of codegen, see Amsterdam Compiler Kit for prior art, among others. GCC approach is on purpose, plus even if they wanted to change, who would take the effort to make existing C, C++, Objective-C, Objective-C++, Fortran, Modula-2, Algol 68, Ada, D, and Go frontends adopt the new architecture? Even clang with all the LLVM modularization is going to take a couple of years to move from plain LLVM IR into MLIR dialect for C based languages, https://github.com/llvm/clangir https://github.com/llvm/clangir
1718627440 10mo ago
It is a political not a technical decision. Essentially the same like the Linux kernel not encouraging the use of out-of-tree kernel modules. https://gcc.gnu.org/legacy-ml/gcc/2000-01/msg00572.html https://gcc.gnu.org/legacy-ml/gcc/2000-01/msg00572.html
- surajrmal 10mo ago
  And it shows how silly the idea is. gcc still sees plenty of forks from vendors who don't upstream, and llvm sees a lot more commercial participation. Unfortunately the Linux kernel equivalent doesn't exist.
  - hedgehog 10mo ago
    There are several open BSDs.
    - School-Cotton 10mo ago
      AFAIK there's no evidence to suggest that permissive vs. copyleft license is the reason for the relative lack of success of the BSDs vs. Linux.
      - pjmlp 10mo ago
        PlayStation and macOS kind of show what happens with upstream. As did all the UNIXes that used to rule before companies started sponsoring Linux kernel development, and were quite happily taking BSD code into them, alongside UNIX System V original code.
  - leoc 10mo ago
    It's also nakedly hypocritical behaviour on Stallman's part. Hoping (whether in vain or not) that GCC being Too Big to Fork ( https://news.ycombinator.com/item?id=6810259 https://news.ycombinator.com/item?id=6810259 ) will keep people from having access to the AST interface really isn't substantially different from saying "why do you need source code, can't you just disassemble the binary hahaha".

I find it shocking that 20 years after LLVM was created, gcc still hasn't moved towards modularization of codegen.

ayende 10mo ago

Isn't that very much intentional on the part of GCC?

demurgos 10mo ago
It is intentional to avoid non-free projects from building on top of gcc components. I am not familiar enough with gcc to know how it impacts out-of-tree free projects or internal development. The decision was taken a long time ago, it may be worth revisiting it.
- janc_ 10mo ago
  Over the years several frontends for languages that used to be out-of-tree for years have been integrated. So both working in-tree & outside are definitely possible.
colejohnson66 10mo ago
Somewhat. Stallman claims to have tried to make it modular,[0] but also that he wants to avoid "misuse of [the] front ends".[1] The idea is that you should link the front and back ends, to prevent out-of-process GPL runarounds. But because of that, the mingling of the front and back ends ended up winning out over attempts to stay modular. [0]: https://lists.gnu.org/archive/html/emacs-devel/2015-02/msg00693.html https://lists.gnu.org/archive/html/emacs-devel/2015-02/msg00... [1]: https://lists.gnu.org/archive/html/emacs-devel/2015-01/msg00015.html https://lists.gnu.org/archive/html/emacs-devel/2015-01/msg00...
- phkahler 10mo ago
  >> The idea is that you should link the front and back ends, to prevent out-of-process GPL runarounds. Valid points, but also the reason people wanting to create a more modular compiler created LLVM under a different license - the ultimate GPL runaround. OTOH now we have two big and useful compilers!
- colechristensen 10mo ago
  Good lord Stallman is such a zealot and hypocrite. It's not open vs. closed it's mine vs. yours and he's openly declaring that he's nerfing software in order to prevent people from using it in a way he doesn't like. And refusing to talk about it in public because normal people hate that shit "misunderstanding" him. --- From the post: I let this drop back in March -- please forgive me. > Maybe that's the issue for GCC, but for Emacs the issue is to get detailed > info out of GCC, which is a different problem. My understanding is that > you're opposed to GCC providing this useful info because that info would > need to be complete enough to be usable as input to a proprietary > compiler backend. My hope is that we can work out a kind of "detailed output" that is enough for what Emacs wants, but not enough for misuse of GCC front ends. I don't want to discuss the details on the list, because I think that would mean 50 messages of misunderstanding and tangents for each message that makes progress. Instead, is there anyone here who would like to work on this in detail?
  - bigfishrunning 10mo ago
    He should just re-license GCC to close whatever perceived loophole, instead of actively making GCC more difficult to work with (for everyone!). RMS has done so much good, but he's so far from an ideal figure.
    - tovej 10mo ago
      How in the world would you relicense GCC
      - colechristensen 10mo ago
        Most contributions are required to assign copyright to the FSF, so it's not actually particularly open. If the FSF is the sole copyright owner they're free to relicense it however they please, if no one else has any controlling interest of the copyright, the GPL doesn't restrict you from relicensing something you're the sole owner of (and it's doubtful there's a legal mechanism to give away rights to something you continue to own) Again, the FSF under Stallman isn't about freedom it's about control.
- giancarlostoro 10mo ago
  That sounds like Stallman wants proprietary OSS ;) If you're going to make it hard for anyone anywhere to integrate with your open source tooling for fear of commercial projects abusing them and not ever sharing their changes, why even use the GPL license?
  - dhosek 10mo ago
    This is a big part of why I’ve always eschewed GPL.
- Croak 10mo ago
  When gcc was built most compilers were proprietary. Stallman wanted a free compiler and to keep it free. The GPL license is more restrictive, but it's philosophy is clear. At the end of the day the code's writer can choose if and how people are allowed to use it. You don't have to use it, you can use something else or build you own. And maybe, just maybe Linux is thriving while Windows is dying because in the Linux ecosystem everybody works together and shares, while in Windows everybody helps together paying for Satya Nadellas next yacht.
  - Y_Y 10mo ago
    > At the end of the day the code's writer can choose if and how people are allowed to use it. If it's free software then I can modify and use it as I please. What's limited is redistributing the modified code (and offering a service to users over a network for Afferro). https://www.gnu.org/philosophy/free-sw.en.html#fs-definition https://www.gnu.org/philosophy/free-sw.en.html#fs-definition
wahern 10mo ago
Not anymore. Modularization is somewhat tangential, but for awhile Stallman did actively oppose rearchitecting GCC to better support non-free plugins and front-ends. But Stallman lost that battle years ago. AFAIU, the current state of GCC is the result of intentional technical choices (certain kinds of decoupling not as beneficial as people might think--Rust has often been stymied by lack of features in LLVM, i.e. defacto (semantic?) coupling), works in progress (decoupling ongoing), or lack of time or wherewithal to commit to certain major changes (decoupling too onerous).
- torginus 10mo ago
  Personally, I think when you are making bad technical decisions in service of legal goals (making it harder to circumvent the GPL), that's a sure sign that you made a wrong turn somewhere.
  - 1718627440 10mo ago
    Why? When your goal is to have free software, having non-free software with better architecture won't suit you.
    - bigstrat2003 10mo ago
      I would describe this more as "trying to prevent others from having non-free software if they wish to", which is a lot more questionable imo.
      - LeFantome 10mo ago
        Some in the Free Software community do not believe that making it harder to collaborate will reduce the amount of software created. For them, you are going to get the software and the choice is just “free” or not. And they imagine that permissively license code bases get “taken” and so copyleft licenses result in more code for “the community”. I happen to believe that barriers to collaboration results in less software for everybody. I look at Clang and GCC and come away thinking that Clang is the better model because it results in more innovation and more software that I can enjoy. Others wonder why I am so naive and say that collaborating on Clang is only for corporate shills and apologists. You can have whatever opinion you want. I do not care about the politics. I just want more Open Source software. I mean, so do the others guys I imagine but they don’t always seem to fact check their theories. We disagree about which model results in more software I can use.

pjmlp 10mo ago

LLVM wasn't the first modularization of codegen, see Amsterdam Compiler Kit for prior art, among others. GCC approach is on purpose, plus even if they wanted to change, who would take the effort to make existing C, C++, Objective-C, Objective-C++, Fortran, Modula-2, Algol 68, Ada, D, and Go frontends adopt the new architecture? Even clang with all the LLVM modularization is going to take a couple of years to move from plain LLVM IR into MLIR dialect for C based languages, https://github.com/llvm/clangir https://github.com/llvm/clangir

1718627440 10mo ago

It is a political not a technical decision. Essentially the same like the Linux kernel not encouraging the use of out-of-tree kernel modules. https://gcc.gnu.org/legacy-ml/gcc/2000-01/msg00572.html https://gcc.gnu.org/legacy-ml/gcc/2000-01/msg00572.html

surajrmal 10mo ago
And it shows how silly the idea is. gcc still sees plenty of forks from vendors who don't upstream, and llvm sees a lot more commercial participation. Unfortunately the Linux kernel equivalent doesn't exist.
- hedgehog 10mo ago
  There are several open BSDs.
  - School-Cotton 10mo ago
    AFAIK there's no evidence to suggest that permissive vs. copyleft license is the reason for the relative lack of success of the BSDs vs. Linux.
    - pjmlp 10mo ago
      PlayStation and macOS kind of show what happens with upstream. As did all the UNIXes that used to rule before companies started sponsoring Linux kernel development, and were quite happily taking BSD code into them, alongside UNIX System V original code.
- leoc 10mo ago
  It's also nakedly hypocritical behaviour on Stallman's part. Hoping (whether in vain or not) that GCC being Too Big to Fork ( https://news.ycombinator.com/item?id=6810259 https://news.ycombinator.com/item?id=6810259 ) will keep people from having access to the AST interface really isn't substantially different from saying "why do you need source code, can't you just disassemble the binary hahaha".