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Avoid checks before _free calls. NFC #24416

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Merged
merged 1 commit into from
May 28, 2025
Merged

Avoid checks before _free calls. NFC #24416

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4 changes: 1 addition & 3 deletions src/Fetch.js
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Original file line number Diff line number Diff line change
Expand Up @@ -414,9 +414,7 @@ function fetchXHR(fetch, onsuccess, onerror, onprogress, onreadystatechange) {
{{{ makeSetValue('fetch', C_STRUCTS.emscripten_fetch_t.status, 'xhr.status', 'i16') }}}
if (xhr.statusText) stringToUTF8(xhr.statusText, fetch + {{{ C_STRUCTS.emscripten_fetch_t.statusText }}}, 64);
onprogress?.(fetch, xhr, e);
if (ptr) {
_free(ptr);
}
_free(ptr);
};
xhr.onreadystatechange = (e) => {
// check if xhr was aborted by user and don't try to call back
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11 changes: 3 additions & 8 deletions src/lib/libbrowser.js
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Expand Up @@ -754,7 +754,7 @@ var LibraryBrowser = {

// To avoid creating worker parent->child chains, always proxies to execute on the main thread.
emscripten_create_worker__proxy: 'sync',
emscripten_create_worker__deps: ['$UTF8ToString', 'malloc', 'free'],
emscripten_create_worker__deps: ['$UTF8ToString', 'realloc'],
emscripten_create_worker: (url) => {
url = UTF8ToString(url);
var id = Browser.workers.length;
Expand All @@ -763,7 +763,6 @@ var LibraryBrowser = {
callbacks: [],
awaited: 0,
buffer: 0,
bufferSize: 0
};
info.worker.onmessage = function info_worker_onmessage(msg) {
if (ABORT) return;
Expand All @@ -781,11 +780,7 @@ var LibraryBrowser = {
var data = msg.data['data'];
if (data) {
if (!data.byteLength) data = new Uint8Array(data);
if (!info.buffer || info.bufferSize < data.length) {
if (info.buffer) _free(info.buffer);
info.bufferSize = data.length;
info.buffer = _malloc(data.length);
}
info.buffer = _realloc(info.buffer, data.length);
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Does realloc do the equivalent check that the buffer size is < the desired length? (i.e. does it avoid the actual reallocation in the case where the existing buffer is big enough?

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Yup, thats exactly what it does

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I think in practice it also never shrinks, but I think that is fine for all these cases.

HEAPU8.set(data, info.buffer);
callbackInfo.func(info.buffer, data.length, callbackInfo.arg);
} else {
Expand All @@ -801,7 +796,7 @@ var LibraryBrowser = {
emscripten_destroy_worker: (id) => {
var info = Browser.workers[id];
info.worker.terminate();
if (info.buffer) _free(info.buffer);
_free(info.buffer);
Browser.workers[id] = null;
},

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10 changes: 3 additions & 7 deletions src/lib/libcore.js
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Expand Up @@ -1299,20 +1299,16 @@ addToLibrary({
// Mark as `noleakcheck` otherwise lsan will report the last returned string
// as a leak.
emscripten_run_script_string__noleakcheck: true,
emscripten_run_script_string__deps: ['$lengthBytesUTF8', '$stringToUTF8', 'malloc'],
emscripten_run_script_string__deps: ['$lengthBytesUTF8', '$stringToUTF8', 'realloc'],
emscripten_run_script_string: (ptr) => {
{{{ makeEval("var s = eval(UTF8ToString(ptr));") }}}
if (s == null) {
return 0;
}
s += '';
var me = _emscripten_run_script_string;
var len = lengthBytesUTF8(s);
if (!me.bufferSize || me.bufferSize < len+1) {
if (me.bufferSize) _free(me.buffer);
me.bufferSize = len+1;
me.buffer = _malloc(me.bufferSize);
}
me.bufferSize = lengthBytesUTF8(s) + 1;
me.buffer = _realloc(me.buffer ?? 0, me.bufferSize)
stringToUTF8(s, me.buffer, me.bufferSize);
return me.buffer;
},
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2 changes: 1 addition & 1 deletion src/lib/libsdl.js
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Original file line number Diff line number Diff line change
Expand Up @@ -483,7 +483,7 @@ var LibrarySDL = {

var info = SDL.surfaces[surf];
if (!info.usePageCanvas && info.canvas) SDL.canvasPool.push(info.canvas);
if (info.buffer) _free(info.buffer);
_free(info.buffer);
_free(info.pixelFormat);
_free(surf);
SDL.surfaces[surf] = null;
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4 changes: 2 additions & 2 deletions src/lib/libstack_trace.js
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Original file line number Diff line number Diff line change
Expand Up @@ -269,7 +269,7 @@ var LibraryStackTrace = {
} else {
name = wasmOffsetConverter.getName(pc);
}
if (_emscripten_pc_get_function.ret) _free(_emscripten_pc_get_function.ret);
_free(_emscripten_pc_get_function.ret ?? 0);
_emscripten_pc_get_function.ret = stringToNewUTF8(name);
return _emscripten_pc_get_function.ret;
#endif
Expand Down Expand Up @@ -311,7 +311,7 @@ var LibraryStackTrace = {
var result = convertPCtoSourceLocation(pc);
if (!result) return 0;

if (_emscripten_pc_get_file.ret) _free(_emscripten_pc_get_file.ret);
_free(_emscripten_pc_get_file.ret ?? 0);
_emscripten_pc_get_file.ret = stringToNewUTF8(result.file);
return _emscripten_pc_get_file.ret;
},
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2 changes: 1 addition & 1 deletion src/lib/libwget.js
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Original file line number Diff line number Diff line change
Expand Up @@ -194,7 +194,7 @@ var LibraryWget = {
var buffer = _malloc(byteArray.length);
HEAPU8.set(byteArray, buffer);
if (onload) {{{ makeDynCall('vippi', 'onload') }}}(handle, userdata, buffer, byteArray.length);
if (free) _free(buffer);
_free(buffer);
} else {
onerrorjs();
}
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8 changes: 2 additions & 6 deletions src/postamble.js
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Expand Up @@ -361,7 +361,7 @@ run();
var workerResponded = false, workerCallbackId = -1;

(() => {
var messageBuffer = null, buffer = 0, bufferSize = 0;
var messageBuffer = null, buffer = 0;

function flushMessages() {
if (!messageBuffer) return;
Expand Down Expand Up @@ -396,11 +396,7 @@ var workerResponded = false, workerCallbackId = -1;
var data = msg.data['data'];
if (data) {
if (!data.byteLength) data = new Uint8Array(data);
if (!buffer || bufferSize < data.length) {
if (buffer) _free(buffer);
bufferSize = data.length;
buffer = _malloc(data.length);
}
buffer = _realloc(buffer, data.length);
HEAPU8.set(data, buffer);
}

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1 change: 1 addition & 0 deletions tools/emscripten.py
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Expand Up @@ -1091,6 +1091,7 @@ def create_pointer_conversion_wrappers(metadata):
'emscripten_builtin_calloc': 'ppp',
'wasmfs_create_node_backend': 'pp',
'malloc': 'pp',
'realloc': 'ppp',
'calloc': 'ppp',
'webidl_malloc': 'pp',
'memalign': 'ppp',
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4 changes: 2 additions & 2 deletions tools/link.py
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Expand Up @@ -1752,9 +1752,9 @@ def limit_incoming_module_api():
# need to be able to call these explicitly.
settings.REQUIRED_EXPORTS += ['__funcs_on_exit']

# The worker code in src/postamble.js depends on malloc/free being exported
# The worker code in src/postamble.js depends on realloc
if settings.BUILD_AS_WORKER:
settings.REQUIRED_EXPORTS += ['malloc', 'free']
settings.REQUIRED_EXPORTS += ['realloc']

if not settings.DISABLE_EXCEPTION_CATCHING:
settings.REQUIRED_EXPORTS += [
Expand Down