1 // The wasm32-unknown-unknown target is currently an experimental version of a
2 // wasm-based target which does *not* use the Emscripten toolchain. Instead
3 // this toolchain is based purely on LLVM's own toolchain, using LLVM's native
4 // WebAssembly backend as well as LLD for a native linker.
6 // There's some trickery below on crate types supported and various defaults
7 // (aka panic=abort by default), but otherwise this is in general a relatively
10 use super::{LldFlavor, LinkerFlavor, Target, TargetOptions, PanicStrategy};
12 pub fn target() -> Result<Target, String> {
13 let opts = TargetOptions {
14 // we allow dynamic linking, but only cdylibs. Basically we allow a
15 // final library artifact that exports some symbols (a wasm module) but
16 // we don't allow intermediate `dylib` crate types
17 dynamic_linking: true,
20 // This means we'll just embed a `start` function in the wasm module
23 // relatively self-explanatory!
24 exe_suffix: ".wasm".to_string(),
25 dll_prefix: String::new(),
26 dll_suffix: ".wasm".to_string(),
29 max_atomic_width: Some(64),
31 // Unwinding doesn't work right now, so the whole target unconditionally
32 // defaults to panic=abort. Note that this is guaranteed to change in
33 // the future once unwinding is implemented. Don't rely on this.
34 panic_strategy: PanicStrategy::Abort,
36 // Wasm doesn't have atomics yet, so tell LLVM that we're in a single
37 // threaded model which will legalize atomics to normal operations.
40 // no dynamic linking, no need for default visibility!
41 default_hidden_visibility: true,
43 // we use the LLD shipped with the Rust toolchain by default
44 linker: Some("rust-lld".to_owned()),
45 lld_flavor: LldFlavor::Wasm,
47 // No need for indirection here, simd types can always be passed by
48 // value as the whole module either has simd or not, which is different
49 // from x86 (for example) where programs can have functions that don't
50 // enable simd features.
51 simd_types_indirect: false,
56 llvm_target: "wasm32-unknown-unknown".to_string(),
57 target_endian: "little".to_string(),
58 target_pointer_width: "32".to_string(),
59 target_c_int_width: "32".to_string(),
60 // This is basically guaranteed to change in the future, don't rely on
61 // this. Use `not(target_os = "emscripten")` for now.
62 target_os: "unknown".to_string(),
63 target_env: String::new(),
64 target_vendor: "unknown".to_string(),
65 data_layout: "e-m:e-p:32:32-i64:64-n32:64-S128".to_string(),
66 arch: "wasm32".to_string(),
67 linker_flavor: LinkerFlavor::Lld(LldFlavor::Wasm),