Don't export memory views by default (#24079)

These memory view are all still available internally within the module
code (i.e. in JS library code, `--pre-js`/`--post-js` code and
`EM_ASM`/`EM_JS`), but to access them externally they now need to be
added to `-sEXPORTED_RUNTIME_METHODS`.

This matches the existing behavior of `-sSTRICT` and
`-sMINIMAL_RUNTIME`.

Anyone trying to access one of these symbols will see the a warning.
e.g. `'HEAP8' was not exported. add it to EXPORTED_RUNTIME_METHODS (see
the Emscripten FAQ)`

Author: sbc100

ChangeLog.md

@@ -358,23 +358,23 @@ addToLibrary({
         // Devices cannot be resized.
         setSize: (file, size) => 0,
         read: (file, buffer, length, offset) => {
-          var bufferArray = Module.HEAP8.subarray(buffer, buffer + length);
+          var bufferArray = HEAP8.subarray(buffer, buffer + length);
           try {
             var bytesRead = definedOps.userRead(wasmFSDeviceStreams[file], bufferArray, 0, length, offset);
           } catch (e) {
             return -e.errno;
           }
-          Module.HEAP8.set(bufferArray, buffer);
+          HEAP8.set(bufferArray, buffer);
           return bytesRead;
         },
         write: (file, buffer, length, offset) => {
-          var bufferArray = Module.HEAP8.subarray(buffer, buffer + length);
+          var bufferArray = HEAP8.subarray(buffer, buffer + length);
           try {
             var bytesWritten = definedOps.userWrite(wasmFSDeviceStreams[file], bufferArray, 0, length, offset);
           } catch (e) {
             return -e.errno;
           }
-          Module.HEAP8.set(bufferArray, buffer);
+          HEAP8.set(bufferArray, buffer);
           return bytesWritten;
         },
       };

src/lib/libwasmfs.js

@@ -39,18 +39,16 @@ var wasmOffsetConverter;
   // Helper function to export a heap symbol on the module object,
   // if requested.
   const shouldExportHeap = (x) => {
-    let shouldExport = !MINIMAL_RUNTIME && !STRICT;
-    if (!shouldExport) {
-      if (MODULARIZE && EXPORT_ALL) {
-        shouldExport = true;
-      } else if (AUDIO_WORKLET && (x == 'HEAPU32' || x == 'HEAPF32')) {
-        // Export to the AudioWorkletGlobalScope the needed variables to access
-        // the heap. AudioWorkletGlobalScope is unable to access global JS vars
-        // in the compiled main JS file.
-        shouldExport = true;
-      } else if (EXPORTED_RUNTIME_METHODS.includes(x)) {
-        shouldExport = true;
-      }
+    let shouldExport = false;
+    if (MODULARIZE && EXPORT_ALL) {
+      shouldExport = true;
+    } else if (AUDIO_WORKLET && (x == 'HEAPU32' || x == 'HEAPF32')) {
+      // Export to the AudioWorkletGlobalScope the needed variables to access
+      // the heap. AudioWorkletGlobalScope is unable to access global JS vars
+      // in the compiled main JS file.
+      shouldExport = true;
+    } else if (EXPORTED_RUNTIME_METHODS.includes(x)) {
+      shouldExport = true;
     }
     return shouldExport;
   }

src/runtime_shared.js

@@ -1 +1 @@
-4091
+3996

test/browser/test_small_js_flags.js.size

@@ -224,13 +224,13 @@ std::u32string get_literal_u32string() {
 
 void force_memory_growth() {
   std::size_t old_size = emscripten_get_heap_size();
-  EM_ASM({"globalThis.oldheap = HEAPU8;"});
+  EM_ASM({"globalThis.oldheap = HEAP8;"});
   assert(val::global("oldheap")["byteLength"].as<size_t>() == old_size);
   emscripten_resize_heap(old_size + EMSCRIPTEN_PAGE_SIZE);
   assert(emscripten_get_heap_size() > old_size);
-  // HEAPU8 on the module should now be rebound, and our oldheap should be
+  // HEAP8 on the module should now be rebound, and our oldheap should be
   // detached
-  assert(val::module_property("HEAPU8")["byteLength"].as<size_t>() > old_size);
+  assert(val::module_property("HEAP8")["byteLength"].as<size_t>() > old_size);
   assert(val::global("oldheap")["byteLength"].as<size_t>() == 0);
 }
 

test/embind/embind_test.cpp

@@ -330,7 +330,7 @@ void test_fs_mmap() {
     assert(stream);
 
     var mapped = FS.mmap(stream, 12, 0, 1 | 2 /* PROT_READ | PROT_WRITE */, 1 /* MAP_SHARED */);
-    var ret = new Uint8Array(Module.HEAPU8.subarray(mapped.ptr, mapped.ptr + 12));
+    var ret = new Uint8Array(HEAPU8.subarray(mapped.ptr, mapped.ptr + 12));
     var fileContents = "";
     for (var i = 0; i < 12; i++) {
       fileContents += String.fromCharCode(ret[i]);
@@ -341,7 +341,7 @@ void test_fs_mmap() {
     ret[9] = 'x'.charCodeAt(0);
     ret[10] = 'y'.charCodeAt(0);
     ret[11] = 'z'.charCodeAt(0);
-    Module.HEAPU8.set(ret, mapped.ptr);
+    HEAPU8.set(ret, mapped.ptr);
 
     // The WasmFS msync syscall requires a pointer to the mapped memory, while the legacy JS API takes in any Uint8Array
     // buffer to write to a file.

test/fs/test_fs_js_api.c

@@ -1 +1 @@
-8271
+8240

test/other/codesize/test_codesize_cxx_ctors1.gzsize

@@ -1 +1 @@
-20032
+19938

test/other/codesize/test_codesize_cxx_ctors1.jssize

@@ -1 +1 @@
-8258
+8229

test/other/codesize/test_codesize_cxx_ctors2.gzsize

@@ -1 +1 @@
-20010
+19916