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// Copyright 2017 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. // The wasm32-unknown-unknown target is currently an experimental version of a // wasm-based target which does *not* use the Emscripten toolchain. Instead // this toolchain is based purely on LLVM's own toolchain, using LLVM's native // WebAssembly backend as well as LLD for a native linker. // // There's some trickery below on crate types supported and various defaults // (aka panic=abort by default), but otherwise this is in general a relatively // standard target. use super::{LldFlavor, LinkerFlavor, Target, TargetOptions, PanicStrategy}; pub fn target() -> Result<Target, String> { let opts = TargetOptions { // we allow dynamic linking, but only cdylibs. Basically we allow a // final library artifact that exports some symbols (a wasm module) but // we don't allow intermediate `dylib` crate types dynamic_linking: true, only_cdylib: true, // This means we'll just embed a `start` function in the wasm module executables: true, // relatively self-explanatory! exe_suffix: ".wasm".to_string(), dll_prefix: "".to_string(), dll_suffix: ".wasm".to_string(), linker_is_gnu: false, // A bit of a lie, but "eh" max_atomic_width: Some(32), // Unwinding doesn't work right now, so the whole target unconditionally // defaults to panic=abort. Note that this is guaranteed to change in // the future once unwinding is implemented. Don't rely on this. panic_strategy: PanicStrategy::Abort, // Wasm doesn't have atomics yet, so tell LLVM that we're in a single // threaded model which will legalize atomics to normal operations. singlethread: true, // no dynamic linking, no need for default visibility! default_hidden_visibility: true, .. Default::default() }; Ok(Target { llvm_target: "wasm32-unknown-unknown-wasm".to_string(), target_endian: "little".to_string(), target_pointer_width: "32".to_string(), target_c_int_width: "32".to_string(), // This is basically guaranteed to change in the future, don't rely on // this. Use `not(target_os = "emscripten")` for now. target_os: "unknown".to_string(), target_env: "".to_string(), target_vendor: "unknown".to_string(), data_layout: "e-m:e-p:32:32-i64:64-n32:64-S128".to_string(), arch: "wasm32".to_string(), linker_flavor: LinkerFlavor::Lld(LldFlavor::Wasm), options: opts, }) }