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Rollup merge of #79997 - coolreader18:wasm-reactor, r=alexcrichton

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Emit a reactor for cdylib target on wasi

Fixes #79199, and relevant to #73432

Implements wasi reactors, as described in WebAssembly/WASI#13 and [`design/application-abi.md`](https://github.com/WebAssembly/WASI/blob/master/design/application-abi.md)

Empty `lib.rs`, `lib.crate-type = ["cdylib"]`:

```shell
$ cargo +reactor build --release --target wasm32-wasi
   Compiling wasm-reactor v0.1.0 (/home/coolreader18/wasm-reactor)
    Finished release [optimized] target(s) in 0.08s
$ wasm-dis target/wasm32-wasi/release/wasm_reactor.wasm >reactor.wat
```
`reactor.wat`:
```wat
(module
 (type $none_=>_none (func))
 (type $i32_=>_none (func (param i32)))
 (type $i32_i32_=>_i32 (func (param i32 i32) (result i32)))
 (type $i32_=>_i32 (func (param i32) (result i32)))
 (type $i32_i32_i32_=>_i32 (func (param i32 i32 i32) (result i32)))
 (import "wasi_snapshot_preview1" "fd_prestat_get" (func $__wasi_fd_prestat_get (param i32 i32) (result i32)))
 (import "wasi_snapshot_preview1" "fd_prestat_dir_name" (func $__wasi_fd_prestat_dir_name (param i32 i32 i32) (result i32)))
 (import "wasi_snapshot_preview1" "proc_exit" (func $__wasi_proc_exit (param i32)))
 (import "wasi_snapshot_preview1" "environ_sizes_get" (func $__wasi_environ_sizes_get (param i32 i32) (result i32)))
 (import "wasi_snapshot_preview1" "environ_get" (func $__wasi_environ_get (param i32 i32) (result i32)))
 (memory $0 17)
 (table $0 1 1 funcref)
 (global $global$0 (mut i32) (i32.const 1048576))
 (global $global$1 i32 (i32.const 1049096))
 (global $global$2 i32 (i32.const 1049096))
 (export "memory" (memory $0))
 (export "_initialize" (func $_initialize))
 (export "__data_end" (global $global$1))
 (export "__heap_base" (global $global$2))
 (func $__wasm_call_ctors
  (call $__wasilibc_initialize_environ_eagerly)
  (call $__wasilibc_populate_preopens)
 )
 (func $_initialize
  (call $__wasm_call_ctors)
 )
 (func $malloc (param $0 i32) (result i32)
  (call $dlmalloc
   (local.get $0)
  )
 )
 ;; lots of dlmalloc, memset/memcpy, & libpreopen code
)
```

I went with repurposing cdylib because I figured that it doesn't make much sense to have a wasi shared library that can't be initialized, and even if someone was using it adding an `_initialize` export is a very small change.
This commit is contained in:
Yuki Okushi 2021-01-12 07:58:59 +09:00 • committed by GitHub
commit 1d83f9828f
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GPG key ID: 4AEE18F83AFDEB23
9 changed files with 69 additions and 20 deletions
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20
compiler/rustc_target/src/spec/crt_objects.rs
View file

@ -5,15 +5,16 @@
//! The `crtx` ones are generally distributed with libc and the `begin/end` ones with gcc.
//! See <https://dev.gentoo.org/~vapier/crt.txt> for some more details.
//!
//! | Pre-link CRT objects | glibc | musl | bionic | mingw | wasi |
//! |----------------------|------------------------|------------------------|------------------|-------------------|------|
//! | dynamic-nopic-exe | crt1, crti, crtbegin | crt1, crti, crtbegin | crtbegin_dynamic | crt2, crtbegin | crt1 |
//! | dynamic-pic-exe | Scrt1, crti, crtbeginS | Scrt1, crti, crtbeginS | crtbegin_dynamic | crt2, crtbegin | crt1 |
//! | static-nopic-exe | crt1, crti, crtbeginT | crt1, crti, crtbegin | crtbegin_static | crt2, crtbegin | crt1 |
//! | static-pic-exe | rcrt1, crti, crtbeginS | rcrt1, crti, crtbeginS | crtbegin_dynamic | crt2, crtbegin | crt1 |
//! | dynamic-dylib | crti, crtbeginS | crti, crtbeginS | crtbegin_so | dllcrt2, crtbegin | - |
//! | static-dylib (gcc) | crti, crtbeginT | crti, crtbeginS | crtbegin_so | dllcrt2, crtbegin | - |
//! | static-dylib (clang) | crti, crtbeginT | N/A | crtbegin_static | dllcrt2, crtbegin | - |
//! | Pre-link CRT objects | glibc | musl | bionic | mingw | wasi |
//! |----------------------|------------------------|------------------------|------------------|-------------------|--------------|
//! | dynamic-nopic-exe | crt1, crti, crtbegin | crt1, crti, crtbegin | crtbegin_dynamic | crt2, crtbegin | crt1 |
//! | dynamic-pic-exe | Scrt1, crti, crtbeginS | Scrt1, crti, crtbeginS | crtbegin_dynamic | crt2, crtbegin | crt1 |
//! | static-nopic-exe | crt1, crti, crtbeginT | crt1, crti, crtbegin | crtbegin_static | crt2, crtbegin | crt1 |
//! | static-pic-exe | rcrt1, crti, crtbeginS | rcrt1, crti, crtbeginS | crtbegin_dynamic | crt2, crtbegin | crt1 |
//! | dynamic-dylib | crti, crtbeginS | crti, crtbeginS | crtbegin_so | dllcrt2, crtbegin | - |
//! | static-dylib (gcc) | crti, crtbeginT | crti, crtbeginS | crtbegin_so | dllcrt2, crtbegin | - |
//! | static-dylib (clang) | crti, crtbeginT | N/A | crtbegin_static | dllcrt2, crtbegin | - |
//! | wasi-reactor-exe | N/A | N/A | N/A | N/A | crt1-reactor |
//!
//! | Post-link CRT objects | glibc | musl | bionic | mingw | wasi |
//! |-----------------------|---------------|---------------|----------------|--------|------|
@ -105,6 +106,7 @@ pub(super) fn pre_wasi_fallback() -> CrtObjects {
(LinkOutputKind::DynamicPicExe, &["crt1.o"]),
(LinkOutputKind::StaticNoPicExe, &["crt1.o"]),
(LinkOutputKind::StaticPicExe, &["crt1.o"]),
(LinkOutputKind::WasiReactorExe, &["crt1-reactor.o"]),
])
}

6
compiler/rustc_target/src/spec/mod.rs
View file

@ -408,6 +408,8 @@ pub enum LinkOutputKind {
DynamicDylib,
/// Dynamic library with bundled libc ("statically linked").
StaticDylib,
/// WASI module with a lifetime past the _initialize entry point
WasiReactorExe,
}
impl LinkOutputKind {
@ -419,6 +421,7 @@ impl LinkOutputKind {
LinkOutputKind::StaticPicExe => "static-pic-exe",
LinkOutputKind::DynamicDylib => "dynamic-dylib",
LinkOutputKind::StaticDylib => "static-dylib",
LinkOutputKind::WasiReactorExe => "wasi-reactor-exe",
}
}
@ -430,6 +433,7 @@ impl LinkOutputKind {
"static-pic-exe" => LinkOutputKind::StaticPicExe,
"dynamic-dylib" => LinkOutputKind::DynamicDylib,
"static-dylib" => LinkOutputKind::StaticDylib,
"wasi-reactor-exe" => LinkOutputKind::WasiReactorExe,
_ => return None,
})
}
@ -1378,7 +1382,7 @@ impl Target {
let kind = LinkOutputKind::from_str(&k).ok_or_else(|| {
format!("{}: '{}' is not a valid value for CRT object kind. \
Use '(dynamic,static)-(nopic,pic)-exe' or \
'(dynamic,static)-dylib'", name, k)
'(dynamic,static)-dylib' or 'wasi-reactor-exe'", name, k)
})?;
let v = v.as_array().ok_or_else(||