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.
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? 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. Referring step 6: emcc.py creates JS wrapper code if needed, does it also creates the html code (optionally)? 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.
