wasi-parallel: implement CPU parallelism

.gitmodules

@@ -13,3 +13,6 @@
 [submodule "crates/wasi-crypto/spec"]
 	path = crates/wasi-crypto/spec
 	url = https://github.com/WebAssembly/wasi-crypto.git
+[submodule "crates/wasi-parallel/spec"]
+	path = crates/wasi-parallel/spec
+	url = https://github.com/WebAssembly/wasi-parallel

Cargo.toml

@@ -30,6 +30,7 @@ wasmtime-wast = { workspace = true }
 wasmtime-wasi = { workspace = true }
 wasmtime-wasi-crypto = { workspace = true, optional = true }
 wasmtime-wasi-nn = { workspace = true, optional = true }
+wasmtime-wasi-parallel = { workspace = true, optional = true }
 clap = { workspace = true, features = ["color", "suggestions", "derive"] }
 anyhow = { workspace = true }
 target-lexicon = { workspace = true }
@@ -114,6 +115,7 @@ wasmtime-wast = { path = "crates/wast", version = "=2.0.0" }
 wasmtime-wasi = { path = "crates/wasi", version = "2.0.0" }
 wasmtime-wasi-crypto = { path = "crates/wasi-crypto", version = "2.0.0" }
 wasmtime-wasi-nn = { path = "crates/wasi-nn", version = "2.0.0" }
+wasmtime-wasi-parallel = { path = "crates/wasi-parallel", version = "2.0.0" }
 wasmtime-component-util = { path = "crates/component-util", version = "=2.0.0" }
 wasmtime-component-macro = { path = "crates/component-macro", version = "=2.0.0" }
 wasmtime-asm-macros = { path = "crates/asm-macros", version = "=2.0.0" }
@@ -178,6 +180,7 @@ jitdump = ["wasmtime/jitdump"]
 vtune = ["wasmtime/vtune"]
 wasi-crypto = ["dep:wasmtime-wasi-crypto"]
 wasi-nn = ["dep:wasmtime-wasi-nn"]
+wasi-parallel = ["wasmtime-wasi-parallel"]
 memory-init-cow = ["wasmtime/memory-init-cow", "wasmtime-cli-flags/memory-init-cow"]
 pooling-allocator = ["wasmtime/pooling-allocator", "wasmtime-cli-flags/pooling-allocator"]
 all-arch = ["wasmtime/all-arch"]

crates/bench-api/src/lib.rs

@@ -473,6 +473,9 @@ impl BenchState {
             wasmtime_wasi_crypto::add_to_linker(&mut linker, |cx| &mut cx.wasi_crypto)?;
         }
 
+        #[cfg(feature = "wasi-parallel")]
+        wasmtime_wasi_parallel::add_to_linker(&mut linker, |cx| &mut cx.wasi_parallel)?;
+
         Ok(Self {
             linker,
             compilation_timer,

crates/cli-flags/src/lib.rs

@@ -60,6 +60,10 @@ pub const SUPPORTED_WASI_MODULES: &[(&str, &str)] = &[
         "experimental-wasi-crypto",
         "enables support for the WASI cryptography APIs (experimental), see https://github.com/WebAssembly/wasi-crypto",
     ),
+    (
+        "experimental-wasi-parallel",
+        "enables support for the WASI parallel APIs (experimental)",
+    ),
 ];
 
 fn pick_profiling_strategy(jitdump: bool, vtune: bool) -> Result<ProfilingStrategy> {
@@ -478,6 +482,7 @@ fn parse_wasi_modules(modules: &str) -> Result<WasiModules> {
                 "wasi-common" => Ok(wasi_modules.wasi_common = enable),
                 "experimental-wasi-nn" => Ok(wasi_modules.wasi_nn = enable),
                 "experimental-wasi-crypto" => Ok(wasi_modules.wasi_crypto = enable),
+                "experimental-wasi-parallel" => Ok(wasi_modules.wasi_parallel = enable),
                 "default" => bail!("'default' cannot be specified with other WASI modules"),
                 _ => bail!("unsupported WASI module '{}'", module),
             };
@@ -509,6 +514,9 @@ pub struct WasiModules {
 
     /// Enable the experimental wasi-crypto implementation.
     pub wasi_crypto: bool,
+
+    /// Enable the experimental wasi-parallel implementation.
+    pub wasi_parallel: bool,
 }
 
 impl Default for WasiModules {
@@ -517,6 +525,7 @@ impl Default for WasiModules {
             wasi_common: true,
             wasi_nn: false,
             wasi_crypto: false,
+            wasi_parallel: false,
         }
     }
 }
@@ -528,6 +537,7 @@ impl WasiModules {
             wasi_common: false,
             wasi_nn: false,
             wasi_crypto: false,
+            wasi_parallel: false,
         }
     }
 }
@@ -674,7 +684,8 @@ mod test {
             WasiModules {
                 wasi_common: true,
                 wasi_nn: false,
-                wasi_crypto: false
+                wasi_crypto: false,
+                wasi_parallel: false
             }
         );
     }
@@ -687,7 +698,8 @@ mod test {
             WasiModules {
                 wasi_common: true,
                 wasi_nn: false,
-                wasi_crypto: false
+                wasi_crypto: false,
+                wasi_parallel: false
             }
         );
     }
@@ -704,7 +716,8 @@ mod test {
             WasiModules {
                 wasi_common: false,
                 wasi_nn: true,
-                wasi_crypto: false
+                wasi_crypto: false,
+                wasi_parallel: false
             }
         );
     }
@@ -718,7 +731,8 @@ mod test {
             WasiModules {
                 wasi_common: false,
                 wasi_nn: false,
-                wasi_crypto: false
+                wasi_crypto: false,
+                wasi_parallel: false
             }
         );
     }

crates/wasi-parallel/.gitignore

@@ -0,0 +1 @@
+/tests/wasm/*

crates/wasi-parallel/Cargo.toml

@@ -0,0 +1,47 @@
+[package]
+name = "wasmtime-wasi-parallel"
+version.workspace = true
+authors.workspace = true
+description = "Wasmtime implementation of the wasi-parallel API"
+documentation = "https://docs.rs/wasmtime-wasi-parallel"
+license = "Apache-2.0 WITH LLVM-exception"
+categories = ["wasm", "parallel"]
+keywords = ["webassembly", "wasm", "parallel"]
+repository = "https://github.com/bytecodealliance/wasmtime"
+readme = "README.md"
+edition = "2018"
+
+[dependencies]
+# These dependencies are necessary for the witx-generation macros to work:
+anyhow = { workspace = true }
+wiggle = { workspace = true }
+
+# These dependencies are necessary for the wasi-parallel implementation:
+indexmap = "1.6"
+log = { workspace = true }
+num_cpus = "1.13"
+rand = "0.8"
+scoped_threadpool = "0.1"
+wasmtime = { workspace = true, default-features = false, features = ["cranelift", "wat"] }
+wasmtime-runtime = { workspace = true }
+wasmtime-wasi = { workspace = true }
+
+[dev-dependencies]
+criterion = "0.4"
+pretty_env_logger = "0.4"
+
+[build-dependencies]
+walkdir = "2.3"
+
+[features]
+# Enable building Rust tests to Wasm. Not all environments will have a
+# `wasm32-wasi` target installed so this feature is not enabled by default.
+build-tests = []
+
+[[bench]]
+name = "nstream"
+harness = false
+
+[[bench]]
+name = "sum"
+harness = false