Automatically convert return pointers to unsigned in CAN_ADDRESS_GB mode. (#19755)

When we have a signature for native function and we know it returns
a pointer we automatically interpret it as unsigned when it arrives in
JS.

Author: sbc100

emscripten.py

@@ -838,8 +838,8 @@ def create_module(receiving, metadata, library_symbols):
     module.append(create_invoke_wrappers(metadata))
   else:
     assert not metadata.invokeFuncs, "invoke_ functions exported but exceptions and longjmp are both disabled"
-  if settings.MEMORY64:
-    module.append(create_wasm64_wrappers(metadata))
+  if settings.MEMORY64 or settings.CAN_ADDRESS_2GB:
+    module.append(create_pointer_conversion_wrappers(metadata))
   return module
 
 
@@ -852,7 +852,7 @@ def create_invoke_wrappers(metadata):
   return invoke_wrappers
 
 
-def create_wasm64_wrappers(metadata):
+def create_pointer_conversion_wrappers(metadata):
   # TODO(sbc): Move this into somewhere less static.  Maybe it can become
   # part of library.js file, even though this metadata relates specifically
   # to native (non-JS) functions.
@@ -902,26 +902,34 @@ def create_wasm64_wrappers(metadata):
     'emscripten_wasm_worker_initialize': '_p_',
   }
 
-  wasm64_wrappers = '''
-function instrumentWasmExportsForMemory64(exports) {
+  wrappers = '''
+function applySignatureConversions(exports) {
   // First, make a copy of the incoming exports object
-  exports = Object.assign({}, exports);'''
+  exports = Object.assign({}, exports);
+'''
 
   sigs_seen = set()
   wrap_functions = []
-  for exp in metadata.exports:
-    sig = mapping.get(exp)
+  for symbol in metadata.exports:
+    sig = mapping.get(symbol)
     if sig:
-      if sig not in sigs_seen:
-        sigs_seen.add(sig)
-        wasm64_wrappers += js_manipulation.make_wasm64_wrapper(sig)
-      wrap_functions.append(exp)
+      if settings.MEMORY64:
+        if sig not in sigs_seen:
+          wrappers += js_manipulation.make_wasm64_wrapper(sig)
+          sigs_seen.add(sig)
+        wrap_functions.append(symbol)
+      elif sig[0] == 'p':
+        if sig not in sigs_seen:
+          wrappers += js_manipulation.make_unsign_pointer_wrapper(sig)
+          sigs_seen.add(sig)
+        wrap_functions.append(symbol)
 
   for f in wrap_functions:
     sig = mapping[f]
-    wasm64_wrappers += f"\n  exports['{f}'] = wasm64Wrapper_{sig}(exports['{f}']);"
-  wasm64_wrappers += '\n  return exports\n}'
-  return wasm64_wrappers
+    wrappers += f"\n  exports['{f}'] = makeWrapper_{sig}(exports['{f}']);"
+  wrappers += '\n  return exports\n}'
+
+  return wrappers
 
 
 def run(in_wasm, out_wasm, outfile_js, memfile, js_syms):

src/embind/embind.js

@@ -718,9 +718,6 @@ var LibraryEmbind = {
         // assumes 4-byte alignment
         var base = _malloc({{{ POINTER_SIZE }}} + length + 1);
         var ptr = base + {{{ POINTER_SIZE }}};
-#if CAN_ADDRESS_2GB
-        ptr >>>= 0;
-#endif
         {{{ makeSetValue('base', '0', 'length', SIZE_TYPE) }}};
         if (stdStringIsUTF8 && valueIsOfTypeString) {
           stringToUTF8(value, ptr, length + 1);
@@ -810,9 +807,6 @@ var LibraryEmbind = {
         // assumes 4-byte alignment
         var length = lengthBytesUTF(value);
         var ptr = _malloc(4 + length + charSize);
-#if CAN_ADDRESS_2GB
-        ptr >>>= 0;
-#endif
         HEAPU32[ptr >> 2] = length >> shift;
 
         encodeString(value, ptr + 4, length + charSize);

src/library.js

@@ -200,7 +200,7 @@ mergeInto(LibraryManager.library, {
   emscripten_resize_heap: (requestedSize) => {
     var oldSize = HEAPU8.length;
 #if MEMORY64 != 1
-    requestedSize = requestedSize >>> 0;
+    requestedSize >>>= 0;
 #endif
 #if ALLOW_MEMORY_GROWTH == 0
 #if ABORTING_MALLOC
@@ -3090,7 +3090,7 @@ mergeInto(LibraryManager.library, {
   // Used by wasm-emscripten-finalize to implement STACK_OVERFLOW_CHECK
   __handle_stack_overflow__deps: ['emscripten_stack_get_base', 'emscripten_stack_get_end', '$ptrToString'],
   __handle_stack_overflow: (requested) => {
-    requested = requested >>> 0;
+    requested >>>= 0;
     var base = _emscripten_stack_get_base();
     var end = _emscripten_stack_get_end();
     abort(`stack overflow (Attempt to set SP to ${ptrToString(requested)}` +

src/library_webgpu.js

@@ -1841,7 +1841,7 @@ var LibraryWebGPU = {
 
     if (size === 0) warnOnce('getMappedRange size=0 no longer means WGPU_WHOLE_MAP_SIZE');
 
-    size = size >>> 0;
+    size >>>= 0;
     if (size === {{{ gpu.WHOLE_MAP_SIZE }}}) size = undefined;
 
     var mapped;
@@ -1875,7 +1875,7 @@ var LibraryWebGPU = {
 
     if (size === 0) warnOnce('getMappedRange size=0 no longer means WGPU_WHOLE_MAP_SIZE');
 
-    size = size >>> 0;
+    size >>>= 0;
     if (size === {{{ gpu.WHOLE_MAP_SIZE }}}) size = undefined;
 
     if (bufferWrapper.mapMode !== {{{ gpu.MapMode.Write }}}) {
@@ -1916,7 +1916,7 @@ var LibraryWebGPU = {
     bufferWrapper.onUnmap = [];
     var buffer = bufferWrapper.object;
 
-    size = size >>> 0;
+    size >>>= 0;
     if (size === {{{ gpu.WHOLE_MAP_SIZE }}}) size = undefined;
 
     // `callback` takes (WGPUBufferMapAsyncStatus status, void * userdata)

src/postamble_minimal.js

@@ -171,8 +171,8 @@ WebAssembly.instantiate(Module['wasm'], imports).then((output) => {
   asm = output.instance.exports;
 #endif
 
-#if MEMORY64
-  asm = instrumentWasmExportsForMemory64(asm);
+#if MEMORY64 || CAN_ADDRESS_2GB
+  asm = applySignatureConversions(asm);
 #endif
 
 #if USE_OFFSET_CONVERTER

src/preamble.js

@@ -991,8 +991,8 @@ function createWasm() {
     reportUndefinedSymbols();
 #endif
 
-#if MEMORY64
-    exports = instrumentWasmExportsForMemory64(exports);
+#if MEMORY64 || CAN_ADDRESS_2GB
+    exports = applySignatureConversions(exports);
 #endif
 
     Module['asm'] = exports;

tools/js_manipulation.py

@@ -182,4 +182,11 @@ def make_wasm64_wrapper(sig):
   # are certain places we need to avoid strict mode still.
   # e.g. emscripten_get_callstack (getCallstack) which uses the `arguments`
   # global.
-  return f'  var wasm64Wrapper_{sig} = (f) => function ({args_in}) {{ return {result} }};\n'
+  return f'  var makeWrapper_{sig} = (f) => function ({args_in}) {{ return {result} }};\n'
+
+
+def make_unsign_pointer_wrapper(sig):
+  assert sig[0] == 'p'
+  n_args = len(sig) - 1
+  args = ','.join('a%d' % i for i in range(n_args))
+  return f'  var makeWrapper_{sig} = (f) => ({args}) => f({args}) >>> 0;\n'