Allow the createWasm function to use async/await where possible

sbc100 · sbc100 · commit 09be3743d4ca · 2024-12-13T12:35:56.000-08:00
The advantage if using `await` in the cases where we can is that it
avoids the generation or wrapper function for each export.

So instead of

```
var wasmExport = createWasm(); // returns empty object
...
var malloc = ((..) =&gt; (malloc = wasmExports['malloc'])()
```

We can just generate:

```
var wasmExport = createWasm(); // returns empty object
...
var malloc = wasmExports['malloc'];
```

This only currently works in MODULARIZE mode where the code is running
inside a factory function.  Otherwise it would end up using
top-level-await.

One wrinkle here is that this is not currently supported when closure is
enabled because we run closure only on the contents of the factory
function so closure ends up seeing this as a top level await when its
not.
diff --git a/src/preamble.js b/src/preamble.js
@@ -1028,11 +1028,11 @@ function getWasmImports() {
     trueModule = null;
 #endif
 #if SHARED_MEMORY || RELOCATABLE
-    receiveInstance(result['instance'], result['module']);
+    return receiveInstance(result['instance'], result['module']);
 #else
     // TODO: Due to Closure regression https://github.com/google/closure-compiler/issues/3193, the above line no longer optimizes out down to the following line.
     // When the regression is fixed, can restore the above PTHREADS-enabled path.
-    receiveInstance(result['instance']);
+    return receiveInstance(result['instance']);
 #endif
   }
 #endif // WASM_ASYNC_COMPILATION
@@ -1068,8 +1068,7 @@ function getWasmImports() {
         // Instantiate from the module posted from the main thread.
         // We can just use sync instantiation in the worker.
         var instance = new WebAssembly.Instance(module, getWasmImports());
-        receiveInstance(instance, module);
-        resolve();
+        resolve(receiveInstance(instance, module));
       };
     });
   }
@@ -1085,11 +1084,11 @@ function getWasmImports() {
   try {
 #endif
     var result = await instantiateAsync(wasmBinary, wasmBinaryFile, info);
-    receiveInstantiationResult(result);
+    var exports = receiveInstantiationResult(result);
 #if LOAD_SOURCE_MAP
     receiveSourceMapJSON(await getSourceMapPromise());
 #endif
-    return result;
+    return exports;
 #if MODULARIZE
   } catch (e) {
     // If instantiation fails, reject the module ready promise.
diff --git a/test/code_size/hello_webgl2_wasm.json b/test/code_size/hello_webgl2_wasm.json
@@ -1,10 +1,10 @@
 {
   "a.html": 454,
   "a.html.gz": 328,
-  "a.js": 4532,
-  "a.js.gz": 2315,
+  "a.js": 4538,
+  "a.js.gz": 2320,
   "a.wasm": 10402,
   "a.wasm.gz": 6703,
-  "total": 15388,
-  "total_gz": 9346
+  "total": 15394,
+  "total_gz": 9351
 }
diff --git a/test/code_size/hello_webgl2_wasm2js.json b/test/code_size/hello_webgl2_wasm2js.json
@@ -1,8 +1,8 @@
 {
   "a.html": 346,
   "a.html.gz": 262,
-  "a.js": 22200,
-  "a.js.gz": 11583,
-  "total": 22546,
-  "total_gz": 11845
+  "a.js": 22206,
+  "a.js.gz": 11589,
+  "total": 22552,
+  "total_gz": 11851
 }
diff --git a/test/code_size/hello_webgl_wasm.json b/test/code_size/hello_webgl_wasm.json
@@ -1,10 +1,10 @@
 {
   "a.html": 454,
   "a.html.gz": 328,
-  "a.js": 4070,
-  "a.js.gz": 2158,
+  "a.js": 4076,
+  "a.js.gz": 2163,
   "a.wasm": 10402,
   "a.wasm.gz": 6703,
-  "total": 14926,
-  "total_gz": 9189
+  "total": 14932,
+  "total_gz": 9194
 }
diff --git a/test/code_size/hello_webgl_wasm2js.json b/test/code_size/hello_webgl_wasm2js.json
@@ -1,8 +1,8 @@
 {
   "a.html": 346,
   "a.html.gz": 262,
-  "a.js": 21726,
-  "a.js.gz": 11413,
-  "total": 22072,
-  "total_gz": 11675
+  "a.js": 21732,
+  "a.js.gz": 11419,
+  "total": 22078,
+  "total_gz": 11681
 }
diff --git a/test/other/codesize/test_codesize_cxx_ctors1.gzsize b/test/other/codesize/test_codesize_cxx_ctors1.gzsize
@@ -1 +1 @@
-8545
+8542
diff --git a/test/other/codesize/test_codesize_cxx_ctors1.jssize b/test/other/codesize/test_codesize_cxx_ctors1.jssize
@@ -1 +1 @@
-20951
+20947
diff --git a/test/other/codesize/test_codesize_cxx_ctors2.gzsize b/test/other/codesize/test_codesize_cxx_ctors2.gzsize
@@ -1 +1 @@
-8530
+8528
diff --git a/test/other/codesize/test_codesize_cxx_ctors2.jssize b/test/other/codesize/test_codesize_cxx_ctors2.jssize
@@ -1 +1 @@
-20919
+20915
diff --git a/test/other/codesize/test_codesize_cxx_except.gzsize b/test/other/codesize/test_codesize_cxx_except.gzsize
@@ -1 +1 @@
-9579
+9578
diff --git a/test/other/codesize/test_codesize_cxx_except.jssize b/test/other/codesize/test_codesize_cxx_except.jssize
@@ -1 +1 @@
-24796
+24792
diff --git a/test/other/codesize/test_codesize_cxx_except_wasm.gzsize b/test/other/codesize/test_codesize_cxx_except_wasm.gzsize
@@ -1 +1 @@
-8508
+8506
diff --git a/test/other/codesize/test_codesize_cxx_except_wasm.jssize b/test/other/codesize/test_codesize_cxx_except_wasm.jssize
@@ -1 +1 @@
-20845
+20841
diff --git a/test/other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize b/test/other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize
@@ -1 +1 @@
-8508
+8506
diff --git a/test/other/codesize/test_codesize_cxx_except_wasm_exnref.jssize b/test/other/codesize/test_codesize_cxx_except_wasm_exnref.jssize
@@ -1 +1 @@
-20845
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diff --git a/test/other/codesize/test_codesize_cxx_lto.gzsize b/test/other/codesize/test_codesize_cxx_lto.gzsize
@@ -1 +1 @@
-8446
+8445
diff --git a/test/other/codesize/test_codesize_cxx_lto.jssize b/test/other/codesize/test_codesize_cxx_lto.jssize
@@ -1 +1 @@
-20530
+20526
diff --git a/test/other/codesize/test_codesize_cxx_mangle.gzsize b/test/other/codesize/test_codesize_cxx_mangle.gzsize
@@ -1 +1 @@
-9580
+9579
diff --git a/test/other/codesize/test_codesize_cxx_mangle.jssize b/test/other/codesize/test_codesize_cxx_mangle.jssize
@@ -1 +1 @@
-24796
+24792
diff --git a/test/other/codesize/test_codesize_cxx_noexcept.gzsize b/test/other/codesize/test_codesize_cxx_noexcept.gzsize
@@ -1 +1 @@
-8545
+8542
diff --git a/test/other/codesize/test_codesize_cxx_noexcept.jssize b/test/other/codesize/test_codesize_cxx_noexcept.jssize
@@ -1 +1 @@
-20951
+20947
diff --git a/test/other/codesize/test_codesize_cxx_wasmfs.gzsize b/test/other/codesize/test_codesize_cxx_wasmfs.gzsize
@@ -1 +1 @@
-3807
+3805
diff --git a/test/other/codesize/test_codesize_cxx_wasmfs.jssize b/test/other/codesize/test_codesize_cxx_wasmfs.jssize
@@ -1 +1 @@
-8588
+8584
diff --git a/test/other/codesize/test_codesize_files_js_fs.gzsize b/test/other/codesize/test_codesize_files_js_fs.gzsize
@@ -1 +1 @@
-7686
+7684
diff --git a/test/other/codesize/test_codesize_files_js_fs.jssize b/test/other/codesize/test_codesize_files_js_fs.jssize
@@ -1 +1 @@
-18858
+18854
diff --git a/test/other/codesize/test_codesize_files_wasmfs.gzsize b/test/other/codesize/test_codesize_files_wasmfs.gzsize
@@ -1 +1 @@
-2906
+2903
diff --git a/test/other/codesize/test_codesize_files_wasmfs.jssize b/test/other/codesize/test_codesize_files_wasmfs.jssize
@@ -1 +1 @@
-6229
+6225
diff --git a/test/other/codesize/test_codesize_hello_O0.gzsize b/test/other/codesize/test_codesize_hello_O0.gzsize
@@ -1 +1 @@
-8021
+8019
diff --git a/test/other/codesize/test_codesize_hello_O0.jssize b/test/other/codesize/test_codesize_hello_O0.jssize
@@ -1 +1 @@
-21551
+21542
diff --git a/test/other/codesize/test_codesize_hello_O1.gzsize b/test/other/codesize/test_codesize_hello_O1.gzsize
@@ -1 +1 @@
-2761
+2758
diff --git a/test/other/codesize/test_codesize_hello_O1.jssize b/test/other/codesize/test_codesize_hello_O1.jssize
@@ -1 +1 @@
-7028
+7016
diff --git a/test/other/codesize/test_codesize_hello_O2.gzsize b/test/other/codesize/test_codesize_hello_O2.gzsize
@@ -1 +1 @@
-2408
+2407
diff --git a/test/other/codesize/test_codesize_hello_O2.jssize b/test/other/codesize/test_codesize_hello_O2.jssize
@@ -1 +1 @@
-4937
+4933
diff --git a/test/other/codesize/test_codesize_hello_O3.gzsize b/test/other/codesize/test_codesize_hello_O3.gzsize
@@ -1 +1 @@
-2320
+2318
diff --git a/test/other/codesize/test_codesize_hello_O3.jssize b/test/other/codesize/test_codesize_hello_O3.jssize
@@ -1 +1 @@
-4784
+4780
diff --git a/test/other/codesize/test_codesize_hello_Os.gzsize b/test/other/codesize/test_codesize_hello_Os.gzsize
@@ -1 +1 @@
-2320
+2318
diff --git a/test/other/codesize/test_codesize_hello_Os.jssize b/test/other/codesize/test_codesize_hello_Os.jssize
@@ -1 +1 @@
-4784
+4780
diff --git a/test/other/codesize/test_codesize_hello_Oz.gzsize b/test/other/codesize/test_codesize_hello_Oz.gzsize
@@ -1 +1 @@
-2301
+2300
diff --git a/test/other/codesize/test_codesize_hello_Oz.jssize b/test/other/codesize/test_codesize_hello_Oz.jssize
@@ -1 +1 @@
-4751
+4747
diff --git a/test/other/codesize/test_codesize_hello_dylink.gzsize b/test/other/codesize/test_codesize_hello_dylink.gzsize
@@ -1 +1 @@
-6198
+6204
diff --git a/test/other/codesize/test_codesize_hello_dylink.jssize b/test/other/codesize/test_codesize_hello_dylink.jssize
@@ -1 +1 @@
-13710
+13727
diff --git a/test/other/codesize/test_codesize_hello_export_nothing.gzsize b/test/other/codesize/test_codesize_hello_export_nothing.gzsize
@@ -1 +1 @@
-1694
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diff --git a/test/other/codesize/test_codesize_hello_export_nothing.jssize b/test/other/codesize/test_codesize_hello_export_nothing.jssize
@@ -1 +1 @@
-3644
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diff --git a/test/other/codesize/test_codesize_hello_wasmfs.gzsize b/test/other/codesize/test_codesize_hello_wasmfs.gzsize
@@ -1 +1 @@
-2320
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diff --git a/test/other/codesize/test_codesize_hello_wasmfs.jssize b/test/other/codesize/test_codesize_hello_wasmfs.jssize
@@ -1 +1 @@
-4784
+4780
diff --git a/test/other/codesize/test_codesize_libcxxabi_message_O3.gzsize b/test/other/codesize/test_codesize_libcxxabi_message_O3.gzsize
@@ -1 +1 @@
-1896
+1893
diff --git a/test/other/codesize/test_codesize_libcxxabi_message_O3.jssize b/test/other/codesize/test_codesize_libcxxabi_message_O3.jssize
@@ -1 +1 @@
-4022
+4018
diff --git a/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.gzsize b/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.gzsize
@@ -1 +1 @@
-1934
+1932
diff --git a/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.jssize b/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.jssize
@@ -1 +1 @@
-4069
+4065
diff --git a/test/other/codesize/test_codesize_mem_O3.jssize b/test/other/codesize/test_codesize_mem_O3.jssize
@@ -1 +1 @@
-4925
+4921
diff --git a/test/other/codesize/test_codesize_mem_O3_grow.gzsize b/test/other/codesize/test_codesize_mem_O3_grow.gzsize
@@ -1 +1 @@
-2503
+2502
diff --git a/test/other/codesize/test_codesize_mem_O3_grow.jssize b/test/other/codesize/test_codesize_mem_O3_grow.jssize
@@ -1 +1 @@
-5210
+5206
diff --git a/test/other/codesize/test_codesize_mem_O3_grow_standalone.gzsize b/test/other/codesize/test_codesize_mem_O3_grow_standalone.gzsize
@@ -1 +1 @@
-2199
+2197
diff --git a/test/other/codesize/test_codesize_mem_O3_grow_standalone.jssize b/test/other/codesize/test_codesize_mem_O3_grow_standalone.jssize
@@ -1 +1 @@
-4618
+4614
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone.gzsize b/test/other/codesize/test_codesize_mem_O3_standalone.gzsize
@@ -1 +1 @@
-2164
+2161
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone.jssize b/test/other/codesize/test_codesize_mem_O3_standalone.jssize
@@ -1 +1 @@
-4548
+4544
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_lib.gzsize b/test/other/codesize/test_codesize_mem_O3_standalone_lib.gzsize
@@ -1 +1 @@
-1921
+1917
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_lib.jssize b/test/other/codesize/test_codesize_mem_O3_standalone_lib.jssize
@@ -1 +1 @@
-4069
+4065
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_narg.gzsize b/test/other/codesize/test_codesize_mem_O3_standalone_narg.gzsize
@@ -1 +1 @@
-1934
+1932
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_narg.jssize b/test/other/codesize/test_codesize_mem_O3_standalone_narg.jssize
@@ -1 +1 @@
-4069
+4065
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.gzsize b/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.gzsize
@@ -1 +1 @@
-1934
+1932
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.jssize b/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.jssize
@@ -1 +1 @@
-4069
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diff --git a/test/other/codesize/test_codesize_minimal_64.gzsize b/test/other/codesize/test_codesize_minimal_64.gzsize
@@ -1 +1 @@
-1469
+1470
diff --git a/test/other/codesize/test_codesize_minimal_64.jssize b/test/other/codesize/test_codesize_minimal_64.jssize
@@ -1 +1 @@
-3124
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diff --git a/test/other/codesize/test_codesize_minimal_O1.gzsize b/test/other/codesize/test_codesize_minimal_O1.gzsize
@@ -1 +1 @@
-1546
+1548
diff --git a/test/other/codesize/test_codesize_minimal_O1.jssize b/test/other/codesize/test_codesize_minimal_O1.jssize
@@ -1 +1 @@
-3693
+3682
diff --git a/test/other/codesize/test_codesize_minimal_O2.gzsize b/test/other/codesize/test_codesize_minimal_O2.gzsize
@@ -1 +1 @@
-1398
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diff --git a/test/other/codesize/test_codesize_minimal_O2.jssize b/test/other/codesize/test_codesize_minimal_O2.jssize
@@ -1 +1 @@
-2829
+2823
diff --git a/test/other/codesize/test_codesize_minimal_O3.gzsize b/test/other/codesize/test_codesize_minimal_O3.gzsize
@@ -1 +1 @@
-1363
+1365
diff --git a/test/other/codesize/test_codesize_minimal_O3.jssize b/test/other/codesize/test_codesize_minimal_O3.jssize
@@ -1 +1 @@
-2779
+2773
diff --git a/test/other/codesize/test_codesize_minimal_Os.gzsize b/test/other/codesize/test_codesize_minimal_Os.gzsize
@@ -1 +1 @@
-1363
+1365
diff --git a/test/other/codesize/test_codesize_minimal_Os.jssize b/test/other/codesize/test_codesize_minimal_Os.jssize
@@ -1 +1 @@
-2779
+2773
diff --git a/test/other/codesize/test_codesize_minimal_Oz-ctors.gzsize b/test/other/codesize/test_codesize_minimal_Oz-ctors.gzsize
@@ -1 +1 @@
-1354
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diff --git a/test/other/codesize/test_codesize_minimal_Oz-ctors.jssize b/test/other/codesize/test_codesize_minimal_Oz-ctors.jssize
@@ -1 +1 @@
-2764
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diff --git a/test/other/codesize/test_codesize_minimal_Oz.gzsize b/test/other/codesize/test_codesize_minimal_Oz.gzsize
@@ -1 +1 @@
-1363
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diff --git a/test/other/codesize/test_codesize_minimal_Oz.jssize b/test/other/codesize/test_codesize_minimal_Oz.jssize
@@ -1 +1 @@
-2779
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diff --git a/test/other/codesize/test_codesize_minimal_pthreads.gzsize b/test/other/codesize/test_codesize_minimal_pthreads.gzsize
@@ -1 +1 @@
-4163
+4170
diff --git a/test/other/codesize/test_codesize_minimal_pthreads.jssize b/test/other/codesize/test_codesize_minimal_pthreads.jssize
@@ -1 +1 @@
-8638
+8654
diff --git a/test/other/codesize/test_codesize_minimal_wasmfs.gzsize b/test/other/codesize/test_codesize_minimal_wasmfs.gzsize
@@ -1 +1 @@
-1363
+1365
diff --git a/test/other/codesize/test_codesize_minimal_wasmfs.jssize b/test/other/codesize/test_codesize_minimal_wasmfs.jssize
@@ -1 +1 @@
-2779
+2773
diff --git a/test/other/test_unoptimized_code_size.js.size b/test/other/test_unoptimized_code_size.js.size
@@ -1 +1 @@
-54298
+54320
diff --git a/test/other/test_unoptimized_code_size_no_asserts.js.size b/test/other/test_unoptimized_code_size_no_asserts.js.size
@@ -1 +1 @@
-29718
+29740
diff --git a/test/other/test_unoptimized_code_size_strict.js.size b/test/other/test_unoptimized_code_size_strict.js.size
@@ -1 +1 @@
-53094
+53116
diff --git a/tools/emscripten.py b/tools/emscripten.py
@@ -885,6 +885,13 @@ def create_sending(metadata, library_symbols):
   return '{\n  ' + ',\n  '.join(elems) + '\n}'
 
 
+def can_use_await():
+  # In modularize mode we can use `await` since the factor function itself
+  # is marked as `async` and the generated code all lives inside that factory
+  # function.
+  return settings.MODULARIZE and not settings.USE_CLOSURE_COMPILER
+
+
 def make_export_wrappers(function_exports):
   assert not settings.MINIMAL_RUNTIME
 
@@ -924,7 +931,7 @@ def install_wrapper(sym):
       # With assertions enabled we create a wrapper that are calls get routed through, for
       # the lifetime of the program.
       wrapper += f"createExportWrapper('{name}', {nargs});"
-    elif settings.WASM_ASYNC_COMPILATION or settings.PTHREADS:
+    elif (settings.WASM_ASYNC_COMPILATION and not can_use_await()) or settings.PTHREADS:
       # With WASM_ASYNC_COMPILATION wrapper will replace the global var and Module var on
       # first use.
       args = [f'a{i}' for i in range(nargs)]
@@ -990,7 +997,11 @@ def create_module(receiving, metadata, global_exports, library_symbols):
 
   if not settings.MINIMAL_RUNTIME:
     if settings.WASM_ASYNC_COMPILATION:
-      module.append("var wasmExports;\ncreateWasm();\n")
+      if can_use_await():
+        # In modullize mode the generated code is within a factory function.
+        module.append("var wasmExports = await createWasm();\n")
+      else:
+        module.append("var wasmExports;\ncreateWasm();\n")
     else:
       module.append("var wasmExports = createWasm();\n")
 
diff --git a/tools/link.py b/tools/link.py

Original file line number	Diff line number	Diff line change
`@@ -1,8 +1,8 @@`
`1`	`1`	`{`
`2`	`2`	`"a.html": 346,`
`3`	`3`	`"a.html.gz": 262,`
`4`		`- "a.js": 22200,`
`5`		`- "a.js.gz": 11583,`
`6`		`- "total": 22546,`
`7`		`- "total_gz": 11845`
	`4`	`+ "a.js": 22206,`
	`5`	`+ "a.js.gz": 11589,`
	`6`	`+ "total": 22552,`
	`7`	`+ "total_gz": 11851`
`8`	`8`	`}`