threads: add feature flags

This adds both the Cargo-level and CLI-level flags for the
shared-everything-threads proposal.

Author: abrown

Cargo.toml

@@ -479,6 +479,7 @@ coredump = ["wasmtime-cli-flags/coredump"]
 addr2line = ["wasmtime/addr2line"]
 debug-builtins = ["wasmtime/debug-builtins"]
 threads = ["wasmtime-cli-flags/threads"]
+shared-everything-threads = ["wasmtime-cli-flags/shared-everything-threads"]
 gc = ["wasmtime-cli-flags/gc", "wasmtime/gc"]
 gc-drc = ["gc", "wasmtime/gc-drc", "wasmtime-cli-flags/gc-drc"]
 gc-null = ["gc", "wasmtime/gc-null", "wasmtime-cli-flags/gc-null"]

crates/cli-flags/Cargo.toml

@@ -38,5 +38,6 @@ gc = ["wasmtime/gc"]
 gc-drc = ["gc", "wasmtime/gc-drc"]
 gc-null = ["gc", "wasmtime/gc-null"]
 threads = ["wasmtime/threads"]
+shared-everything-threads = ["wasmtime/shared-everything-threads"]
 memory-protection-keys = ["wasmtime/memory-protection-keys"]
 pulley = ["wasmtime/pulley"]

crates/cli-flags/src/lib.rs

@@ -358,6 +358,8 @@ wasmtime_option_group! {
         pub tail_call: Option<bool>,
         /// Configure support for the threads proposal.
         pub threads: Option<bool>,
+        /// Configure support for the shared-everything-threads proposal.
+        pub shared_everything_threads: Option<bool>,
         /// Configure support for the memory64 proposal.
         pub memory64: Option<bool>,
         /// Configure support for the component-model proposal.
@@ -995,6 +997,7 @@ impl CommonOptions {
             ("component-model", component_model_multiple_returns, wasm_component_model_multiple_returns)
             ("component-model-async", component_model_async, wasm_component_model_async)
             ("threads", threads, wasm_threads)
+            ("shared-everything-threads", shared_everything_threads, wasm_shared_everything_threads)
             ("gc", gc, wasm_gc)
             ("gc", reference_types, wasm_reference_types)
             ("gc", function_references, wasm_function_references)

crates/cranelift/Cargo.toml

@@ -46,3 +46,4 @@ gc = ["wasmtime-environ/gc"]
 gc-drc = ["gc", "wasmtime-environ/gc-drc"]
 gc-null = ["gc", "wasmtime-environ/gc-null"]
 threads = ["wasmtime-environ/threads"]
+shared-everything-threads = ["wasmtime-environ/shared-everything-threads"]

crates/environ/Cargo.toml

@@ -65,6 +65,7 @@ compile = [
   "dep:wasmprinter",
 ]
 threads = ['std']
+shared-everything-threads = ['std']
 wmemcheck = ['std']
 std = [
   'anyhow/std',

crates/wasmtime/Cargo.toml

@@ -309,6 +309,12 @@ threads = [
   "std",
 ]
 
+# Enable runtime support for the WebAssembly shared-everything-threads proposal.
+shared-everything-threads = [
+  "wasmtime-cranelift?/shared-everything-threads",
+  "std",
+]
+
 # Controls whether backtraces will attempt to parse DWARF information in
 # WebAssembly modules and components to provide filenames and line numbers in
 # stack traces.

crates/wasmtime/src/config.rs

@@ -849,6 +849,21 @@ impl Config {
         self
     }
 
+    /// Configures whether the WebAssembly [shared-everything-threads] proposal
+    /// will be enabled for compilation.
+    ///
+    /// This feature gates extended use of the `shared` attribute on items other
+    /// than memories, extra atomic instructions, and new component model
+    /// intrinsics for spawning threads. It depends on the
+    /// [`wasm_threads`][Self::wasm_threads] being enabled.
+    ///
+    /// [shared-everything-threads]:
+    ///     https://github.com/webassembly/shared-everything-threads
+    pub fn wasm_shared_everything_threads(&mut self, enable: bool) -> &mut Self {
+        self.wasm_feature(WasmFeatures::SHARED_EVERYTHING_THREADS, enable);
+        self
+    }
+
     /// Configures whether the [WebAssembly reference types proposal][proposal]
     /// will be enabled for compilation.
     ///