Avoid repeating wasm data in SINGLE_FILE mode with closure. NFC

This change removes the `wasmBinaryFile` global in SINGLE_FILE mode.
Instead the `wasmBinaryFile` is inlined into the `createWasm` function.

As part of this change we now also use the same embedding method as is
used in `MINIMAL_RUNTIME`, avoiding the need for the `tryParseAsDataURI`
helper.

Fixes: #23938

Author: sbc100

src/lib/libbase64.js

@@ -43,24 +43,4 @@ addToLibrary({
     }
     return output;
   },
-
-  // Prefix of data URIs emitted by SINGLE_FILE and related options.
-  // Double quotes here needed, othersise jsifier will not include any in the
-  // output.
-  $dataURIPrefix: "'data:application/octet-stream;base64,'",
-
-  /**
-   * Indicates whether filename is a base64 data URI.
-   */
-  $isDataURI: (filename) => filename.startsWith(dataURIPrefix),
-
-  // If filename is a base64 data URI, parses and returns data (Buffer on node,
-  // Uint8Array otherwise). If filename is not a base64 data URI, returns
-  // undefined.
-  $tryParseAsDataURI__deps: ['$base64Decode', '$isDataURI', '$dataURIPrefix'],
-  $tryParseAsDataURI: (filename) => {
-    if (isDataURI(filename)) {
-      return base64Decode(filename.slice(dataURIPrefix.length));
-    }
-  },
 });

src/preamble.js

@@ -578,13 +578,12 @@ function resetPrototype(constructor, attrs) {
 #endif
 
 #if !SOURCE_PHASE_IMPORTS
-#if SINGLE_FILE
-// In SINGLE_FILE mode the wasm binary is encoded inline here as a data: URL.
-var wasmBinaryFile = '{{{ WASM_BINARY_FILE }}}';
-#else
 var wasmBinaryFile;
 
 function findWasmBinary() {
+#if SINGLE_FILE && WASM == 1 && !WASM2JS
+  return base64Decode('<<< WASM_BINARY_DATA >>>');
+#else
 #if EXPORT_ES6 && !AUDIO_WORKLET
   if (Module['locateFile']) {
 #endif
@@ -599,18 +598,19 @@ function findWasmBinary() {
   // Use bundler-friendly `new URL(..., import.meta.url)` pattern; works in browsers too.
   return new URL('{{{ WASM_BINARY_FILE }}}', import.meta.url).href;
 #endif
-}
 #endif
+}
 
 function getBinarySync(file) {
+#if SINGLE_FILE && WASM == 1 && !WASM2JS
+  if (ArrayBuffer.isView(file)) {
+    return file;
+  }
+#endif
+#if expectToReceiveOnModule('wasmBinary') || MAYBE_WASM2JS
   if (file == wasmBinaryFile && wasmBinary) {
     return new Uint8Array(wasmBinary);
   }
-#if SUPPORT_BASE64_EMBEDDING
-  var binary = tryParseAsDataURI(file);
-  if (binary) {
-    return binary;
-  }
 #endif
   if (readBinary) {
     return readBinary(file);
@@ -1024,9 +1024,7 @@ function getWasmImports() {
   var exports = receiveInstantiationResult({instance, 'module':wasmModule});
   return exports;
 #else
-#if !SINGLE_FILE
   wasmBinaryFile ??= findWasmBinary();
-#endif
 #if WASM_ASYNC_COMPILATION
 #if RUNTIME_DEBUG
   dbg('asynchronously preparing wasm');

test/other/codesize/test_codesize_hello_single_file.gzsize

@@ -1 +1 @@
-3826
+3720

test/other/codesize/test_codesize_hello_single_file.jssize

@@ -1 +1 @@
-12217
+6824

test/other/test_unoptimized_code_size_strict.js.size

@@ -1 +1 @@
-50961
+50872

tools/emscripten.py

@@ -297,12 +297,8 @@ def emscript(in_wasm, out_wasm, outfile_js, js_syms, finalize=True, base_metadat
   #     to use emscripten's wasm<->JS ABI
   #   * Use the metadata to generate the JS glue that goes with the wasm
 
-  if settings.SINGLE_FILE:
-    # placeholder strings for JS glue, to be replaced with subresource locations in do_binaryen
-    settings.WASM_BINARY_FILE = '<<< WASM_BINARY_FILE >>>'
-  else:
-    # set file locations, so that JS glue can find what it needs
-    settings.WASM_BINARY_FILE = js_manipulation.escape_for_js_string(os.path.basename(out_wasm))
+  # set file locations, so that JS glue can find what it needs
+  settings.WASM_BINARY_FILE = js_manipulation.escape_for_js_string(os.path.basename(out_wasm))
 
   if finalize:
     metadata = finalize_wasm(in_wasm, out_wasm, js_syms)

tools/link.py

@@ -1951,10 +1951,7 @@ def phase_emscript(in_wasm, wasm_target, js_syms, base_metadata):
   # the module is already in JS format.
   if settings.SINGLE_FILE and not settings.WASM2JS:
     settings.SUPPORT_BASE64_EMBEDDING = 1
-    if settings.MINIMAL_RUNTIME:
-      settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE.append('$base64Decode')
-    else:
-      settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE.append('$tryParseAsDataURI')
+    settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE.append('$base64Decode')
 
   if shared.SKIP_SUBPROCS:
     return
@@ -2371,10 +2368,7 @@ def phase_binaryen(target, options, wasm_target):
   if final_js and settings.SINGLE_FILE and not settings.WASM2JS:
     js = read_file(final_js)
 
-    if settings.MINIMAL_RUNTIME:
-      js = do_replace(js, '<<< WASM_BINARY_DATA >>>', base64_encode(wasm_target))
-    else:
-      js = do_replace(js, '<<< WASM_BINARY_FILE >>>', get_subresource_location(wasm_target))
+    js = do_replace(js, '<<< WASM_BINARY_DATA >>>', base64_encode(wasm_target))
     delete_file(wasm_target)
     write_file(final_js, js)