path: root/.gitmodules
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authorAlex Crichton <>2017-10-22 20:01:00 -0700
committerAlex Crichton <>2017-11-19 21:07:41 -0800
commit80ff0f74b0c4a8d384160af81a1b21f53622d8af (patch)
tree0f9bd959bf437c8da2497433fd936d285f912e61 /.gitmodules
parentAuto merge of #45528 - alexcrichton:avx512, r=arielb1 (diff)
std: Add a new wasm32-unknown-unknown target
This commit adds a new target to the compiler: wasm32-unknown-unknown. This target is a reimagining of what it looks like to generate WebAssembly code from Rust. Instead of using Emscripten which can bring with it a weighty runtime this instead is a target which uses only the LLVM backend for WebAssembly and a "custom linker" for now which will hopefully one day be direct calls to lld. Notable features of this target include: * There is zero runtime footprint. The target assumes nothing exists other than the wasm32 instruction set. * There is zero toolchain footprint beyond adding the target. No custom linker is needed, rustc contains everything. * Very small wasm modules can be generated directly from Rust code using this target. * Most of the standard library is stubbed out to return an error, but anything related to allocation works (aka `HashMap`, `Vec`, etc). * Naturally, any `#[no_std]` crate should be 100% compatible with this new target. This target is currently somewhat janky due to how linking works. The "linking" is currently unconditional whole program LTO (aka LLVM is being used as a linker). Naturally that means compiling programs is pretty slow! Eventually though this target should have a linker. This target is also intended to be quite experimental. I'm hoping that this can act as a catalyst for further experimentation in Rust with WebAssembly. Breaking changes are very likely to land to this target, so it's not recommended to rely on it in any critical capacity yet. We'll let you know when it's "production ready". --- Currently testing-wise this target is looking pretty good but isn't complete. I've got almost the entire `run-pass` test suite working with this target (lots of tests ignored, but many passing as well). The `core` test suite is still getting LLVM bugs fixed to get that working and will take some time. Relatively simple programs all seem to work though! --- It's worth nothing that you may not immediately see the "smallest possible wasm module" for the input you feed to rustc. For various reasons it's very difficult to get rid of the final "bloat" in vanilla rustc (again, a real linker should fix all this). For now what you'll have to do is: cargo install --git wasm-gc foo.wasm bar.wasm And then `bar.wasm` should be the smallest we can get it! --- In any case for now I'd love feedback on this, particularly on the various integration points if you've got better ideas of how to approach them!
Diffstat (limited to '.gitmodules')
1 files changed, 6 insertions, 0 deletions
diff --git a/.gitmodules b/.gitmodules
index 2802c8d639..0a1188e83e 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -42,3 +42,9 @@
42[submodule "src/tools/miri"] 42[submodule "src/tools/miri"]
43 path = src/tools/miri 43 path = src/tools/miri
44 url = 44 url =
45[submodule "src/dlmalloc"]
46 path = src/dlmalloc
47 url =
48[submodule "src/binaryen"]
49 path = src/binaryen
50 url =