Hi Sam, please excuse my late response. Thank you for all your answers! This helped me so much.
>From all those information you gave me, I tried to make a diagram to summarize the process of Emscripten while creating C->Wasm. See the picture below. Did I got it right now? [image: Emscripten C-to-Wasm Sketch.png] I am wondering if these information are documented somewhere. Since I need those information for my uni paper, I have to list the sources and refer to "official" documents. s...@google.com schrieb am Montag, 5. Juni 2023 um 04:46:48 UTC+2: > On Fri, Jun 2, 2023 at 11:40 PM René N. <withe...@gmail.com> wrote: > >> Thank you for answering Sam! Very glad to get a feedback this quick. >> >> So if I understand it correctly, emcc is doing the whole C -> Wasm Binary >> since it's the driver of the whole toolchain, right? >> I think I am irritated because emcc is called "Emscripten Compiler >> *Frontend*". So I thought that emcc is just a part of the compilation >> process since a "Frontend" to me is the component of a compiler which takes >> a source code and generates the IR while the Backend is takes the IR and >> generates the target language. >> > > You are right, it is not quite correct to call emcc a frontend, since it > doesn't actually parse any code. clang is both a compiler driver, and a C > frontend. > >> >> Also I would like to ask: Where does the "(upstream) LLVM WebAssembly >> Backend" comes into play? It should be in step 3 (LLVM IR -> wasm object >> file), right? >> > > Yes. > > >> >> Referring to step 4 & 5: While wasm-opt is a Binaryen-Tool, wasm-ld is a >> LLVM tool, right? I'm asking this because Emscripten's website >> <https://emscripten.org/docs/compiling/WebAssembly.html> says, that >> "Emscripten's WebAssembly support depends on Binaryen". This statement >> seems wrong, since (non-optimized) Wasm Binary is generated without >> Binaryen. >> > > Historically it has been true that binaryen was always required, but > fairly recently we have made it possible to perform complete debug builds > without binaryen (by moving a lot of things that binaryen used to do into > python code in emscripten). The documentation is a little inaccurate > there. However, to build anything for production (i.e.. any release > build) binaryen is required, so I think we can still think of it as a > required dependency of emscirpten. Binaryen is also requires even for > debug builds in some cases (for example if you use asyncify there is no way > to avoid it). > > >> Referring step 6: emcc.py creates JS wrapper code if needed, does it also >> creates the html code (optionally)? >> > > Yes it can optionally create both JS and HTML. > > >> >> >> Thanks again for helping me understand Emscripten and toolchains in >> general! >> >> s...@google.com schrieb am Freitag, 2. Juni 2023 um 19:00:21 UTC+2: >> >>> Hi René, >>> >>> Great questions. It sounds like you have a pretty good understanding of >>> the various phases. I will reiterate your list, filling in a few details >>> for you. At the high level emcc is the compiler driver, rather than the >>> compiler itself. gcc and clang both take this roll too, and under the hood >>> both clang and gcc fork separate processes for the actual compiling and >>> linking. >>> >>> emcc -> >>> 1. clang.exe: C-Code -> LLVM IR >>> 2. clang.exe: LLVM IR -> LLVM IR (optimized) (clang/llvm) ( this >>> really happens as part of (1) when you build with optimizations enabled) >>> 3. clang.exe: LLVM IR -> wasm object file >>> 4. wasm-ld.exe: combine files -> Wasm Binary >>> 5. wasm-opt.exe: Wasm Binary -> Optimized Wasm Binary (optional) >>> 6. emcc.py: Generate JS wrapper code (optional) >>> >>> >>> On Fri, Jun 2, 2023 at 9:25 AM René N. <withe...@gmail.com> wrote: >>> >>>> Hello guys, >>>> >>>> for a uni paper I need to explain how Emscripten works (on >>>> higher-level) to emit WebAssembly-Binary in the end. >>>> I'm new into compilers and toolchains and I'm not sure if I understand >>>> it correctly, how Emscripten is converting compatible code (like C) to >>>> WebAssembly Binary. >>>> >>>> If I got it right, for creating .wasm, these tools are used by >>>> Emscripten: >>>> >>>> - emsdk as configurator for the whole toolchain >>>> - emcc (which includes Clang+LLVM) >>>> - the (upstream) LLVM WebAssembly Backend >>>> - Binaryen >>>> >>>> So if i got it right, to create .wasm, the compilation works like this: >>>> >>>> 1. C-Code -> LLVM IR >>>> 2. LLVM IR -> LLVM IR (optimized) >>>> 3. LLVM IR (optimized) -> Wasm Binary >>>> 4. Wasm Binary -> Wasm Binary (optimized) >>>> 5. (Wasm Binary (optimized) -> JS) [optional] >>>> >>>> Did I forget something? >>>> >>>> What I am especially unsure of, is, which tool is doing what: >>>> So emcc uses Clang+LLVM. Now I'm not sure if emcc emits LLVM IR only >>>> (since Clang is creating LLVM IR), or does it also convert it to emit Wasm >>>> Binary (which means that the upstream LLVM Wasm Backend lies in the emcc)? >>>> What I'm quite sure of, is that step 1 is done by Clang and steps 4 & 5 >>>> are done by Binaryen. >>>> >>>> Also, to me it seems like 'emcc' has 2 different meanings: 1. as >>>> part(!!) of the compilation process and 2. as command representation for >>>> the whole toolchain >>>> >>>> Also, which component/tool of Emscripten is creating the JS and HTML >>>> Gluecode? >>>> >>>> I'm happy if someone can help me out! >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "emscripten-discuss" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to emscripten-disc...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/emscripten-discuss/3efb5151-1d5c-4ae1-89a5-b37ed3085793n%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/emscripten-discuss/3efb5151-1d5c-4ae1-89a5-b37ed3085793n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >> You received this message because you are subscribed to the Google Groups >> "emscripten-discuss" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to emscripten-disc...@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/emscripten-discuss/495eeb80-5d31-4d6a-a15d-92c9b215151fn%40googlegroups.com >> >> <https://groups.google.com/d/msgid/emscripten-discuss/495eeb80-5d31-4d6a-a15d-92c9b215151fn%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to emscripten-discuss+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/emscripten-discuss/8b07e3ae-db8a-45f7-ab48-ef293964405en%40googlegroups.com.
