9 ms·

Cheerp 3.0: C++ compiler for the Web, now permissively licensed

195 points by apignotti 4y ago

ognarb 4y ago
This looks interesting, does anyone tried it before and can comment on how good this work on a real world project?
- wyldfire 4y ago
  I'm particularly curious on what parts cheerp adds to their clang+llvm base. Presumably it's something like the C standard target library for WASM/JS? For reference, here's examples of what you could do with the baseline clang with wasm (but not JS?) [1] [2] [3], referenced from a similar thread on HN. [1] https://github.com/ern0/howto-wasm-minimal https://github.com/ern0/howto-wasm-minimal [2] https://github.com/robrohan/wefx https://github.com/robrohan/wefx [3] https://github.com/PetterS/clang-wasm https://github.com/PetterS/clang-wasm
  - yuri91 4y ago
    Disclaimer: I work on Cheerp. We do include the C (Musl) and C++ (Clang's libcxx) standard libraries. And we do have some custom LLVM passes to improve code size and performance (See for example [1] and [2]). But the main selling point in my opinion is the ability to target JavaScript, and (almost) freely mix data and code compiled to either JS or Wasm. Emscripten can also target JS, but it still retains the linear memory model of Wasm (or X86, Arm, ...), which means that what you get in the end is a big TypedArray and operations on it using basic types. With Cheerp, code compiled to JS uses an object memory model: a C++ object will become a garbage-collected JS object. While this has some limitations (you can't do unsafe casts and treat your memory like it's a big array, because it isn't), it allows seamless integration with the Browser (or any third-party) APIs: - You can store a DOM element directly in your C++ objects (instead of doing everything through tables) - You can directly manipulate JS Strings instead of constantly converting back and forth to C strings - You can create nice zero-overhead interfaces to use your C++ classes from manually written JS - Or, you can just write your whole program in C++, including callbacks for DOM events and whatnot And you can still compile the peformance-sensitive or type-unsafe parts of your code to Wasm (losing access to some convenience in exchange for speed). You can get an idea from the Pong tutorial [3], although it's a bit of a contrived example to showcase what can be done. [1] https://medium.com/leaningtech/partialexecuter-reducing-webassembly-size-by-exploring-all-executions-in-llvm-f1ee295e8ba https://medium.com/leaningtech/partialexecuter-reducing-weba... [2] https://docs.leaningtech.com/cheerp/Cheerp-PreExecuter.html https://docs.leaningtech.com/cheerp/Cheerp-PreExecuter.html [3] https://docs.leaningtech.com/cheerp/Cheerp-Tutorial-Mixed-mode-C++-to-WebAssembly-and-JavaScript https://docs.leaningtech.com/cheerp/Cheerp-Tutorial-Mixed-mo...
    - prideout 4y ago
      > a C++ object will become a garbage-collected JS object. This sounds great for ease-of-use and cross-language binding. But, there's a downside with respect to performance. With Emscripten, you never see any GC events show up in the profiler.
      - yuri91 4y ago
        Indeed, as I said it can be a downside. What we usually suggest is to compile most of the application to Wasm (which is also the default), and move the parts that most interact with the outside world to JS. This can actually result in a speedup if it avoids multiple back-and-forths between JS and Wasm, which is common if you use a Browser/JS api from Wasm.
Laaas 4y ago
I'm waiting for the same thing to happen to CheerpX [0]. Would be great to be able to sandbox x86 code trivially. [0]: https://news.ycombinator.com/item?id=25646022 https://news.ycombinator.com/item?id=25646022 [0]: https://docs.leaningtech.com/cheerpx/ https://docs.leaningtech.com/cheerpx/
- nunobrito 4y ago
  CheerpJ is the one I'm waiting for. That thing is wicked cool for Java.
  - Laaas 4y ago
    https://docs.leaningtech.com/cheerpj/ https://docs.leaningtech.com/cheerpj/
    - KRAKRISMOTT 4y ago
      It's not open source
      - Laaas 4y ago
        Yes, unfortunately, the more advanced products are much more restricted.
  - TeaVMFan 4y ago
    While you wait for CheerpJ, please check out TeaVM: https://teavm.org/ https://teavm.org/ It has a permissive Apache license and numerous success stories: https://frequal.com/TeaVM/TeaVmBasedSites.html https://frequal.com/TeaVM/TeaVmBasedSites.html There is also a full SPA toolkit called Flavour Plus for making pure Java, web-native, full-stack web apps: https://frequal.com/FlavourPlus/ https://frequal.com/FlavourPlus/
    - merb 4y ago
      Cheerpj or Teavm would be amazing if they would be able to convert pdfbox to wasm as a library that runs on wasi and the web.
azakai 4y ago
> Cheerp directly uses the LLVM bytecode format as the intermediate representation, for both object files and libraries. The paragraph with this might be a little confusing. It suggests that this is a benefit of Cheerp, but upstream LLVM (and Emscripten, which uses upstream LLVM) can do the exact same thing if you build with -flto to enable LTO. The benefit of upstream LLVM is that it can do both LTO and non-LTO builds. Non-LTO builds link much, much faster in a large project, since the linker is only concatenating wasm object files, just like a normal linker. That can matter a lot for CI times and local debugging etc.
- hummus_bae 4y ago
  Thanks for the input. This paragraph is indeed a selling point of Cheerp. "if you build with -flto to enable LTO" is only true if you run on Linux since LLVM LTO support on Windows and Mac is limited.
  - azakai 4y ago
    That is not true for compiling to wasm. You can use upstream LLVM (and Emscripten, which uses it) with -flto normally on all platforms. It is basically cross-compiling, so it does not matter at all on what platform you are building, and Windows/Mac/Linux all work the same. Just to confirm that, here is an Emscripten CI run on MacOS, where you can see among other tests ones that build with lto (search for "lto" in the "run tests" tab): https://app.circleci.com/pipelines/github/emscripten-core/emscripten/25864/workflows/36f40a77-7f74-4dd3-a661-eb834c3990da/jobs/603241 https://app.circleci.com/pipelines/github/emscripten-core/em...
  - smeenai 4y ago
    Limited in what way? LLVM LTO works seamlessly if you use LLD on both macOS and Windows; that's what Chrome does, for example. LLVM LTO also works pretty seamlessly with ld64 on macOS; the linker needs libLTO, but the driver takes care of that for you.
- Pet_Ant 4y ago
  Apparently LTO = "Link-Time Optimisation" ? https://en.wikipedia.org/wiki/Interprocedural_optimization#WPO_and_LTO https://en.wikipedia.org/wiki/Interprocedural_optimization#W...
goodpoint 4y ago
> Since its release in 2014 Cheerp has been licensed under a dual licensing scheme: GPLv2 for non-commercial users, and a proprietary license for anybody not willing to comply with GPLv2 terms. Using exclusively GPLv3 would have been better.
dang 4y ago
Related: Cheerp: A C++ Compiler for the Web - https://news.ycombinator.com/item?id=15727346 https://news.ycombinator.com/item?id=15727346 - Nov 2017 (9 comments) Cheerp 1.2 – C++ to JavaScript: faster than Emscripten with dynamic memory - https://news.ycombinator.com/item?id=11018516 https://news.ycombinator.com/item?id=11018516 - Feb 2016 (21 comments) Cheerp 1.1 – C++ for the Web with fast startup times, dynamic memory - https://news.ycombinator.com/item?id=10524784 https://news.ycombinator.com/item?id=10524784 - Nov 2015 (20 comments) Cheerp – A C/C++ compiler for web applications - https://news.ycombinator.com/item?id=8167536 https://news.ycombinator.com/item?id=8167536 - Aug 2014 (49 comments)
ihnorton 4y ago
Does the library side of this provide an emulated socket API? The CheerJ docs [1] say: > Not yet. The main problem is that RuneScape requires low level network connections primitives (sockets) So, I'm guessing the same applies to the C++ version? [1] https://docs.leaningtech.com/cheerpj/Frequently-Asked-Questions.html#can-i-play-old-school-runescape-using-cheerpj-or-the-cheerpj-applet-runner-extension https://docs.leaningtech.com/cheerpj/Frequently-Asked-Questi...
- apignotti 4y ago
  We don't support sockets out-of-the-box yet, but we have built a solution for the "networking-from-the-browser" problem a few months ago and we may backport that to Cheerp eventually. https://leaningtech.com/webvm-virtual-machine-with-networking-via-tailscale/ https://leaningtech.com/webvm-virtual-machine-with-networkin...
jeffreportmill1 4y ago
Congratulations, looks like a great release! I'm a big fan of CheerpJ - these tools are making web development from other languages a reality.
jawadch93 4y ago
[dead]
deleted 4y ago
[deleted]
Karellen 4y ago
> You can download Cheerp here. For Debian/Ubuntu, consider using our PPA > https://launchpad.net/~leaningtech-dev/+archive/ubuntu/cheerp-ppa https://launchpad.net/~leaningtech-dev/+archive/ubuntu/cheer... They recommend using an Ubuntu PPA with Debian? That's... definitely a bold strategy. Let's hope it works out for them. I mean, given that they themselves suggest doing so, I take it that's the PPA has been properly tested on Debian, and that they'll answer support requests and help resolving any issues if they crop up? There aren't any Debian releases listed in the "Display sources.list entries for:" dropdown. Hmmm....following a couple of documentation links, I get to: https://docs.leaningtech.com/cheerp/Ubuntu-Debian-installation-using-PPA https://docs.leaningtech.com/cheerp/Ubuntu-Debian-installati... Which states "Manually edit sources.list (works on Debian testing / stretch)". Huh. testing / stretch. Yup, I'm sure it's fiiiiine.
jokoon 4y ago
It can actually manipulate the DOM by writing JS code. This is really amazing. > The question is, what will you build with Cheerp? I don't really know, for now all I want is executing python in the browser like brython, and see if WASM can make things better, at least give more elegant errors. But other than that, I'd rather dump HTML as a format and have something better suited for it. I already thought about a replacement for HTML, because there are so many things to remove in HTML.
- CyberDildonics 4y ago
  It can actually manipulate the DOM by writing JS code. This is really amazing. Why is that amazing? Anyone can manipulate the DOM by writing javascript. I don't really know, for now all I want is executing python in the browser You might want that, but do people using what you make want that? Python is already orders of magnitude slower than a native program, it's going to be even slower running in a browser.
  - jokoon 4y ago
    Manipulating the DOM with C++ means one doesn't have to write JS at all, and can use C++. Even things like TS still rely heavy machinery to translate ts to js. I don't really know how TS works and if it puts the generated JS in cache. Well brython is already quite fast already, so I don't think a WASM version would be worse. And python performance is not such a big problem, it's up to developers to write faster programs instead by picking relevant modules and not writing low-level code. Python performance has already improved a bit, and performance is rarely a real problem in software anyway.
    - josephg 4y ago
      > I don't really know how TS works and if it puts the generated JS in cache. Usually, typescript is compiled to javascript in a build step (eg on the developer’s computer) using the typescript compiler. The output is javascript which can be run in the web browser directly, or bundled with webpack & friends, then loaded into the browser.
    - 4y ago
pull_my_finger 4y ago
Does Cheerp expose a C API or is it cpp only?
- apignotti 4y ago
  Cheerp works with C code, it's also possible to use __attribute__((cheerp_jsexport)) as an equivalent to [[cheerp::jsexporp]]. Accessing DOM / external JavaScript can be done by using the __asm__ syntax while in C, use of the client namespace is only possible from C++ code
dgfitz 4y ago
How is this much different than wt [1] or compiling qt to emscripten? Sincere question. [1] https://www.webtoolkit.eu/wt https://www.webtoolkit.eu/wt
ar9av 4y ago
That's awesome. I don't know how exactly that compares to Emscripten, some things in Emscripten were a bit awkward. I wonder how the C++ to WASM compilation landscape changes through this.

195 points by apignotti 4y ago

ognarb 4y ago

This looks interesting, does anyone tried it before and can comment on how good this work on a real world project?

wyldfire 4y ago
I'm particularly curious on what parts cheerp adds to their clang+llvm base. Presumably it's something like the C standard target library for WASM/JS? For reference, here's examples of what you could do with the baseline clang with wasm (but not JS?) [1] [2] [3], referenced from a similar thread on HN. [1] https://github.com/ern0/howto-wasm-minimal https://github.com/ern0/howto-wasm-minimal [2] https://github.com/robrohan/wefx https://github.com/robrohan/wefx [3] https://github.com/PetterS/clang-wasm https://github.com/PetterS/clang-wasm
- yuri91 4y ago
  Disclaimer: I work on Cheerp. We do include the C (Musl) and C++ (Clang's libcxx) standard libraries. And we do have some custom LLVM passes to improve code size and performance (See for example [1] and [2]). But the main selling point in my opinion is the ability to target JavaScript, and (almost) freely mix data and code compiled to either JS or Wasm. Emscripten can also target JS, but it still retains the linear memory model of Wasm (or X86, Arm, ...), which means that what you get in the end is a big TypedArray and operations on it using basic types. With Cheerp, code compiled to JS uses an object memory model: a C++ object will become a garbage-collected JS object. While this has some limitations (you can't do unsafe casts and treat your memory like it's a big array, because it isn't), it allows seamless integration with the Browser (or any third-party) APIs: - You can store a DOM element directly in your C++ objects (instead of doing everything through tables) - You can directly manipulate JS Strings instead of constantly converting back and forth to C strings - You can create nice zero-overhead interfaces to use your C++ classes from manually written JS - Or, you can just write your whole program in C++, including callbacks for DOM events and whatnot And you can still compile the peformance-sensitive or type-unsafe parts of your code to Wasm (losing access to some convenience in exchange for speed). You can get an idea from the Pong tutorial [3], although it's a bit of a contrived example to showcase what can be done. [1] https://medium.com/leaningtech/partialexecuter-reducing-webassembly-size-by-exploring-all-executions-in-llvm-f1ee295e8ba https://medium.com/leaningtech/partialexecuter-reducing-weba... [2] https://docs.leaningtech.com/cheerp/Cheerp-PreExecuter.html https://docs.leaningtech.com/cheerp/Cheerp-PreExecuter.html [3] https://docs.leaningtech.com/cheerp/Cheerp-Tutorial-Mixed-mode-C++-to-WebAssembly-and-JavaScript https://docs.leaningtech.com/cheerp/Cheerp-Tutorial-Mixed-mo...
  - prideout 4y ago
    > a C++ object will become a garbage-collected JS object. This sounds great for ease-of-use and cross-language binding. But, there's a downside with respect to performance. With Emscripten, you never see any GC events show up in the profiler.
    - yuri91 4y ago
      Indeed, as I said it can be a downside. What we usually suggest is to compile most of the application to Wasm (which is also the default), and move the parts that most interact with the outside world to JS. This can actually result in a speedup if it avoids multiple back-and-forths between JS and Wasm, which is common if you use a Browser/JS api from Wasm.

Laaas 4y ago

I'm waiting for the same thing to happen to CheerpX [0]. Would be great to be able to sandbox x86 code trivially. [0]: https://news.ycombinator.com/item?id=25646022 https://news.ycombinator.com/item?id=25646022 [0]: https://docs.leaningtech.com/cheerpx/ https://docs.leaningtech.com/cheerpx/

nunobrito 4y ago
CheerpJ is the one I'm waiting for. That thing is wicked cool for Java.
- Laaas 4y ago
  https://docs.leaningtech.com/cheerpj/ https://docs.leaningtech.com/cheerpj/
  - KRAKRISMOTT 4y ago
    It's not open source
    - Laaas 4y ago
      Yes, unfortunately, the more advanced products are much more restricted.
- TeaVMFan 4y ago
  While you wait for CheerpJ, please check out TeaVM: https://teavm.org/ https://teavm.org/ It has a permissive Apache license and numerous success stories: https://frequal.com/TeaVM/TeaVmBasedSites.html https://frequal.com/TeaVM/TeaVmBasedSites.html There is also a full SPA toolkit called Flavour Plus for making pure Java, web-native, full-stack web apps: https://frequal.com/FlavourPlus/ https://frequal.com/FlavourPlus/
  - merb 4y ago
    Cheerpj or Teavm would be amazing if they would be able to convert pdfbox to wasm as a library that runs on wasi and the web.

azakai 4y ago

> Cheerp directly uses the LLVM bytecode format as the intermediate representation, for both object files and libraries. The paragraph with this might be a little confusing. It suggests that this is a benefit of Cheerp, but upstream LLVM (and Emscripten, which uses upstream LLVM) can do the exact same thing if you build with -flto to enable LTO. The benefit of upstream LLVM is that it can do both LTO and non-LTO builds. Non-LTO builds link much, much faster in a large project, since the linker is only concatenating wasm object files, just like a normal linker. That can matter a lot for CI times and local debugging etc.

hummus_bae 4y ago
Thanks for the input. This paragraph is indeed a selling point of Cheerp. "if you build with -flto to enable LTO" is only true if you run on Linux since LLVM LTO support on Windows and Mac is limited.
- azakai 4y ago
  That is not true for compiling to wasm. You can use upstream LLVM (and Emscripten, which uses it) with -flto normally on all platforms. It is basically cross-compiling, so it does not matter at all on what platform you are building, and Windows/Mac/Linux all work the same. Just to confirm that, here is an Emscripten CI run on MacOS, where you can see among other tests ones that build with lto (search for "lto" in the "run tests" tab): https://app.circleci.com/pipelines/github/emscripten-core/emscripten/25864/workflows/36f40a77-7f74-4dd3-a661-eb834c3990da/jobs/603241 https://app.circleci.com/pipelines/github/emscripten-core/em...
- smeenai 4y ago
  Limited in what way? LLVM LTO works seamlessly if you use LLD on both macOS and Windows; that's what Chrome does, for example. LLVM LTO also works pretty seamlessly with ld64 on macOS; the linker needs libLTO, but the driver takes care of that for you.
Pet_Ant 4y ago
Apparently LTO = "Link-Time Optimisation" ? https://en.wikipedia.org/wiki/Interprocedural_optimization#WPO_and_LTO https://en.wikipedia.org/wiki/Interprocedural_optimization#W...

goodpoint 4y ago

> Since its release in 2014 Cheerp has been licensed under a dual licensing scheme: GPLv2 for non-commercial users, and a proprietary license for anybody not willing to comply with GPLv2 terms. Using exclusively GPLv3 would have been better.

dang 4y ago

Related: Cheerp: A C++ Compiler for the Web - https://news.ycombinator.com/item?id=15727346 https://news.ycombinator.com/item?id=15727346 - Nov 2017 (9 comments) Cheerp 1.2 – C++ to JavaScript: faster than Emscripten with dynamic memory - https://news.ycombinator.com/item?id=11018516 https://news.ycombinator.com/item?id=11018516 - Feb 2016 (21 comments) Cheerp 1.1 – C++ for the Web with fast startup times, dynamic memory - https://news.ycombinator.com/item?id=10524784 https://news.ycombinator.com/item?id=10524784 - Nov 2015 (20 comments) Cheerp – A C/C++ compiler for web applications - https://news.ycombinator.com/item?id=8167536 https://news.ycombinator.com/item?id=8167536 - Aug 2014 (49 comments)

ihnorton 4y ago

Does the library side of this provide an emulated socket API? The CheerJ docs [1] say: > Not yet. The main problem is that RuneScape requires low level network connections primitives (sockets) So, I'm guessing the same applies to the C++ version? [1] https://docs.leaningtech.com/cheerpj/Frequently-Asked-Questions.html#can-i-play-old-school-runescape-using-cheerpj-or-the-cheerpj-applet-runner-extension https://docs.leaningtech.com/cheerpj/Frequently-Asked-Questi...

apignotti 4y ago
We don't support sockets out-of-the-box yet, but we have built a solution for the "networking-from-the-browser" problem a few months ago and we may backport that to Cheerp eventually. https://leaningtech.com/webvm-virtual-machine-with-networking-via-tailscale/ https://leaningtech.com/webvm-virtual-machine-with-networkin...

jeffreportmill1 4y ago

Congratulations, looks like a great release! I'm a big fan of CheerpJ - these tools are making web development from other languages a reality.

jawadch93 4y ago

[dead]

deleted 4y ago

[deleted]

Karellen 4y ago

> You can download Cheerp here. For Debian/Ubuntu, consider using our PPA > https://launchpad.net/~leaningtech-dev/+archive/ubuntu/cheerp-ppa https://launchpad.net/~leaningtech-dev/+archive/ubuntu/cheer... They recommend using an Ubuntu PPA with Debian? That's... definitely a bold strategy. Let's hope it works out for them. I mean, given that they themselves suggest doing so, I take it that's the PPA has been properly tested on Debian, and that they'll answer support requests and help resolving any issues if they crop up? There aren't any Debian releases listed in the "Display sources.list entries for:" dropdown. Hmmm....following a couple of documentation links, I get to: https://docs.leaningtech.com/cheerp/Ubuntu-Debian-installation-using-PPA https://docs.leaningtech.com/cheerp/Ubuntu-Debian-installati... Which states "Manually edit sources.list (works on Debian testing / stretch)". Huh. testing / stretch. Yup, I'm sure it's fiiiiine.

jokoon 4y ago

It can actually manipulate the DOM by writing JS code. This is really amazing. > The question is, what will you build with Cheerp? I don't really know, for now all I want is executing python in the browser like brython, and see if WASM can make things better, at least give more elegant errors. But other than that, I'd rather dump HTML as a format and have something better suited for it. I already thought about a replacement for HTML, because there are so many things to remove in HTML.

CyberDildonics 4y ago
It can actually manipulate the DOM by writing JS code. This is really amazing. Why is that amazing? Anyone can manipulate the DOM by writing javascript. I don't really know, for now all I want is executing python in the browser You might want that, but do people using what you make want that? Python is already orders of magnitude slower than a native program, it's going to be even slower running in a browser.
- jokoon 4y ago
  Manipulating the DOM with C++ means one doesn't have to write JS at all, and can use C++. Even things like TS still rely heavy machinery to translate ts to js. I don't really know how TS works and if it puts the generated JS in cache. Well brython is already quite fast already, so I don't think a WASM version would be worse. And python performance is not such a big problem, it's up to developers to write faster programs instead by picking relevant modules and not writing low-level code. Python performance has already improved a bit, and performance is rarely a real problem in software anyway.
  - josephg 4y ago
    > I don't really know how TS works and if it puts the generated JS in cache. Usually, typescript is compiled to javascript in a build step (eg on the developer’s computer) using the typescript compiler. The output is javascript which can be run in the web browser directly, or bundled with webpack & friends, then loaded into the browser.
  - 4y ago

pull_my_finger 4y ago

Does Cheerp expose a C API or is it cpp only?

apignotti 4y ago
Cheerp works with C code, it's also possible to use __attribute__((cheerp_jsexport)) as an equivalent to [[cheerp::jsexporp]]. Accessing DOM / external JavaScript can be done by using the __asm__ syntax while in C, use of the client namespace is only possible from C++ code

dgfitz 4y ago

How is this much different than wt [1] or compiling qt to emscripten? Sincere question. [1] https://www.webtoolkit.eu/wt https://www.webtoolkit.eu/wt

ar9av 4y ago

That's awesome. I don't know how exactly that compares to Emscripten, some things in Emscripten were a bit awkward. I wonder how the C++ to WASM compilation landscape changes through this.