Expose WebAssembly.Instance

Author: daxpedda

crates/cli-support/src/intrinsic.rs

@@ -252,6 +252,9 @@ intrinsics! {
         #[symbol = "__wbindgen_memory"]
         #[signature = fn() -> Externref]
         Memory,
+        #[symbol = "__wbindgen_instance"]
+        #[signature = fn() -> Externref]
+        Instance,
         #[symbol = "__wbindgen_module"]
         #[signature = fn() -> Externref]
         Module,

crates/cli-support/src/js/mod.rs

@@ -274,8 +274,8 @@ impl<'a> Context<'a> {
         shim.push_str(
             "
             const wasmModule = new WebAssembly.Module(bytes);
-            const wasmInstance = new WebAssembly.Instance(wasmModule, imports);
-            wasm = wasmInstance.exports;
+            instance = new WebAssembly.Instance(wasmModule, imports);
+            wasm = instance.exports;
             module.exports.__wasm = wasm;
         ",
         );
@@ -345,8 +345,8 @@ impl<'a> Context<'a> {
                     throw new Error(`Unsupported protocol: ${{wasm_url.protocol}}`);
             }}
 
-            const wasmInstance = (await WebAssembly.instantiate(wasmCode, imports)).instance;
-            const wasm = wasmInstance.exports;",
+            const instance = (await WebAssembly.instantiate(wasmCode, imports)).instance;
+            const wasm = instance.exports;",
             module_name = module_name
         )
     }
@@ -385,6 +385,7 @@ impl<'a> Context<'a> {
                         script_src = new URL(document.currentScript.src, location.href).toString();
                     }\n",
                 );
+                js.push_str("let instance;\n");
                 js.push_str("let wasm;\n");
                 init = self.gen_init(needs_manual_start, None)?;
                 footer.push_str(&format!(
@@ -400,6 +401,7 @@ impl<'a> Context<'a> {
             } => {
                 js.push_str(&self.generate_node_imports());
 
+                js.push_str("let instance;\n");
                 js.push_str("let wasm;\n");
 
                 for (id, js) in crate::sorted_iter(&self.wasm_import_definitions) {
@@ -464,6 +466,7 @@ impl<'a> Context<'a> {
 
                 self.imports_post.push_str(
                     "\
+                    let instance;
                     let wasm;
                     export function __wbg_set_wasm(val) {
                         wasm = val;
@@ -481,6 +484,7 @@ impl<'a> Context<'a> {
             // expose the same initialization function as `--target no-modules`
             // as the default export of the module.
             OutputMode::Web => {
+                self.imports_post.push_str("let instance;\n");
                 self.imports_post.push_str("let wasm;\n");
                 init = self.gen_init(needs_manual_start, Some(&mut imports))?;
                 footer.push_str("export { initSync }\n");
@@ -860,7 +864,7 @@ impl<'a> Context<'a> {
                         module = new WebAssembly.Module(module);
                     }}
 
-                    const instance = new WebAssembly.Instance(module, imports);
+                    instance = new WebAssembly.Instance(module, imports);
 
                     return finalizeInit(instance, module);
                 }}
@@ -3498,6 +3502,11 @@ impl<'a> Context<'a> {
                 format!("init.__wbindgen_wasm_module")
             }
 
+            Intrinsic::Instance => {
+                assert_eq!(args.len(), 0);
+                "wasm".to_string()
+            }
+
             Intrinsic::Memory => {
                 assert_eq!(args.len(), 0);
                 let mut memories = self.module.memories.iter();

src/lib.rs

@@ -1082,6 +1082,7 @@ externs! {
 
         fn __wbindgen_not(idx: u32) -> u32;
 
+        fn __wbindgen_instance() -> u32;
         fn __wbindgen_memory() -> u32;
         fn __wbindgen_module() -> u32;
         fn __wbindgen_function_table() -> u32;
@@ -1358,6 +1359,11 @@ pub fn module() -> JsValue {
     unsafe { JsValue::_new(__wbindgen_module()) }
 }
 
+/// Returns a handle to this wasm instance's `WebAssembly.Instance`
+pub fn instance() -> JsValue {
+    unsafe { JsValue::_new(__wbindgen_instance()) }
+}
+
 /// Returns a handle to this wasm instance's `WebAssembly.Memory`
 pub fn memory() -> JsValue {
     unsafe { JsValue::_new(__wbindgen_memory()) }