Cleanup source map loading (#24967)

- Move LOAD_SOURCE_MAP to settings_internal. Its set whenever source
maps are used with ASAN and really is only used internally. We have no
tests that set it explicitly.
- Move all code to `source_map_support.js`
- Load `source_map_support.js` during postamble. This does run under
`MINIMAL_RUNTIME`, but `LOAD_SOURCE_MAP` has always been no-op on
`MINIMAL_RUNTIME` anyway.

Author: sbc100

ChangeLog.md

@@ -20,6 +20,9 @@ See docs/process.md for more on how version tagging works.
 
 4.0.14 (in development)
 -----------------------
+- The `LOAD_SOURCE_MAP` setting was made an internal setting.  This was always
+  an internal detail of the sanitizers, which is enabled automatically when
+  needed, so setting it explicitly should never be needed. (#24967)
 - The wasm offset converter was removed along with the `WASM_OFFSET_CONVERTER`
   setting. This feature only existed to work around an old v8 bug that was fixed
   back in 2019. (#24963)

site/source/docs/tools_reference/settings_reference.rst

@@ -3053,16 +3053,6 @@ future release.
 
 Default value: -1
 
-.. _load_source_map:
-
-LOAD_SOURCE_MAP
-===============
-
-Whether we should load the WASM source map at runtime.
-This is enabled automatically when using -gsource-map with sanitizers.
-
-Default value: false
-
 .. _source_map_prefixes:
 
 SOURCE_MAP_PREFIXES

src/postamble.js

@@ -13,6 +13,10 @@ if (ENVIRONMENT_IS_WORKER) {
 }
 #endif
 
+#if LOAD_SOURCE_MAP
+#include "source_map_support.js"
+#endif
+
 #if DETERMINISTIC
 #include "deterministic.js"
 #endif

src/preamble.js

@@ -410,25 +410,6 @@ function instrumentWasmTableWithAbort() {
 }
 #endif
 
-#if LOAD_SOURCE_MAP
-function receiveSourceMapJSON(sourceMap) {
-  wasmSourceMap = new WasmSourceMap(sourceMap);
-  {{{ runIfMainThread("removeRunDependency('source-map');") }}}
-}
-#endif
-
-#if (PTHREADS || WASM_WORKERS) && LOAD_SOURCE_MAP
-// When using postMessage to send an object, it is processed by the structured
-// clone algorithm.  The prototype, and hence methods, on that object is then
-// lost. This function adds back the lost prototype.  This does not work with
-// nested objects that has prototypes, but it suffices for WasmSourceMap and
-// WasmOffsetConverter.
-function resetPrototype(constructor, attrs) {
-  var object = Object.create(constructor.prototype);
-  return Object.assign(object, attrs);
-}
-#endif
-
 #if !SOURCE_PHASE_IMPORTS && !WASM_ESM_INTEGRATION
 var wasmBinaryFile;
 
@@ -557,9 +538,6 @@ function instantiateSync(file, info) {
   module = new WebAssembly.Module(binary);
 #endif // NODE_CODE_CACHING
   var instance = new WebAssembly.Instance(module, info);
-#if LOAD_SOURCE_MAP
-  receiveSourceMapJSON(getSourceMap());
-#endif
   return [instance, module];
 }
 #endif
@@ -785,10 +763,6 @@ function getWasmImports() {
   addRunDependency('wasm-instantiate');
 #endif
 
-#if LOAD_SOURCE_MAP
-  {{{ runIfMainThread("addRunDependency('source-map');") }}}
-#endif
-
   // Prefer streaming instantiation if available.
 #if WASM_ASYNC_COMPILATION
 #if ASSERTIONS
@@ -865,9 +839,6 @@ function getWasmImports() {
 #endif
   var result = await instantiateAsync(wasmBinary, wasmBinaryFile, info);
   var exports = receiveInstantiationResult(result);
-#if LOAD_SOURCE_MAP
-  receiveSourceMapJSON(await getSourceMapAsync());
-#endif
   return exports;
 #else // WASM_ASYNC_COMPILATION
   var result = instantiateSync(wasmBinaryFile, info);

src/runtime_common.js

@@ -55,11 +55,6 @@ if (ENVIRONMENT_IS_NODE && {{{ ENVIRONMENT_IS_WORKER_THREAD() }}}) {
 #include "audio_worklet.js"
 #endif
 
-#if LOAD_SOURCE_MAP
-var wasmSourceMap;
-#include "source_map_support.js"
-#endif
-
 // Memory management
 
 #if !WASM_ESM_INTEGRATION || IMPORTED_MEMORY

src/settings.js

@@ -2006,10 +2006,6 @@ var MINIFY_HTML = true;
 // [link]
 var ASAN_SHADOW_SIZE = -1;
 
-// Whether we should load the WASM source map at runtime.
-// This is enabled automatically when using -gsource-map with sanitizers.
-var LOAD_SOURCE_MAP = false;
-
 // List of path substitutions to apply in the "sources" field of the source map.
 // Corresponds to the ``--prefix`` option used in ``tools/wasm-sourcemap.py``.
 // Must be used with ``-gsource-map``.

src/settings_internal.js

@@ -272,3 +272,7 @@ var INCLUDE_WEBGL1_FALLBACK = true;
 var MINIFICATION_MAP = '';
 
 var OUTPUT_FORMAT = '';
+
+// Whether we should load the WASM source map at runtime.
+// This is enabled automatically when using -gsource-map with sanitizers.
+var LOAD_SOURCE_MAP = false;

src/source_map_support.js

@@ -90,8 +90,12 @@ class WasmSourceMap {
   }
 }
 
-var wasmSourceMapFile = '{{{ WASM_BINARY_FILE }}}.map';
-wasmSourceMapFile = locateFile(wasmSourceMapFile);
+var wasmSourceMap;
+var wasmSourceMapFile = locateFile('{{{ WASM_BINARY_FILE }}}.map');
+
+function receiveSourceMapJSON(sourceMap) {
+  wasmSourceMap = new WasmSourceMap(sourceMap);
+}
 
 function getSourceMap() {
   var buf = readBinary(wasmSourceMapFile);
@@ -109,3 +113,23 @@ async function getSourceMapAsync() {
   }
   return getSourceMap();
 }
+
+
+#if PTHREADS || WASM_WORKERS
+// Source map is received via postMessage on worker threads.
+if ({{{ ENVIRONMENT_IS_MAIN_THREAD() }}}) {
+#endif
+
+#if WASM_ASYNC_COMPILATION
+addRunDependency('source-map');
+getSourceMapAsync().then((json) => {
+  receiveSourceMapJSON(json);
+  removeRunDependency('source-map');
+});
+#else
+receiveSourceMapJSON(getSourceMap());
+#endif
+
+#if PTHREADS || WASM_WORKERS
+}
+#endif