On Fri, Jun 2, 2023 at 11:40 PM René N. <wither2...@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-discuss+unsubscr...@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. 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