How to use custom build of clang (and modules) #23391
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Replies: 3 comments 12 replies
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The version of clang that comes with emscripten/emsdk is basically tip-of-tree so you should not need to use a custom version just to get module support (i.e. the version of clang we ship should have all the latest module support). However, emscripten itself still doesn't have integrated module support. See #21987 for example. However if you do want to use your down version of clang when |
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emscripten uses the current stable llvm release for libc++ and libc++abi. That means its currently LLVM 19. Looking at the history it looks like that |
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You can see it was added here: llvm/llvm-project#98643. After the llvm 19 branch point. |
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Yes, the version of LLVM we use is tip-ot-tree, but the version of the llvm libraries like libc++ we only update on major releases. For example we recently updated for llvm 19: #22994. The next update won't be until the llvm 20 release date I'm afraid. |
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If you really want to this bleeding edge C++23 support you could try updating the copy of libc++ in emscripten. We have a script for doing this called |
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It looks like maybe emscripten-glfw is not yet setup for |
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Regarding gen_sig_info.py, currently that only works for builtin libraries. For external libraries you still need to add/maintain the Regarding the overheads of memory64, yes there are some. Just like on native platforms switching to 64-bit has performance and memory cost due to increased sizes of your data structures. This used more memory and negatively effects cache locality. IIUC this is normally just a few percent slowdown. With WebAssembly there is also the additional cost of using memory64 which is that some of the tricks that are used to avoid bounds checks do not work with 64-bit memories, which will have a performance impact.. IIUC this is normally in the 5-10% range. |
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@sbc100 Hi Sam. I was looking into this issue, and it seems that the only thing I need to do is to manually add a void emscripten_glfw3_context_init(emscripten::glfw3::Context *iContext,
float iScale,
ScaleChangeCallback, WindowResizeCallback, KeyboardCallback, ClipboardStringCallback, RequestFullscreen, ErrorHandler); emscripten_glfw3_context_init__deps: ['$specialHTMLTargets'],
emscripten_glfw3_context_init__proxy: 'sync',
emscripten_glfw3_context_init__sig: 'vpfpppppp', // <- add this?
emscripten_glfw3_context_init: (context, scale, scaleChangeCallback, windowResizeCallback, keyboardCallback, clipboardCallback, requestFullscreen, errorHandler) => {I assume I probably also need to add entries for all new Do I need the port file to also do something special with the |
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Yes, any function that takes or returns a pointer value (or a size_t/intptr_t) value needs to have a You can check No need to handle |
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I have created PR that implements the changes discussed to support wasm64 |
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If you really want to this bleeding edge C++23 support you could try updating the copy of libc++ in emscripten. We have a script for doing this called
./system/lib/update_libcxx.pywhich we use, but its not really designed for end users. You could also try just dropping in the missing header file intosystem/lib/libcxx. Once you have updated you can run./embuilder build sysroot libcxxor you can run./emcc --clear-cacheto clear the cache and rebuild everything.