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Fix closure errors with MINIMAL_RUNTIME + USE_PTHREADS. NFC. #14936

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Merged
merged 1 commit into from
Aug 24, 2021
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Fix closure errors with MINIMAL_RUNTIME + USE_PTHREADS. NFC. #14936

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1 change: 1 addition & 0 deletions emcc.py
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Expand Up @@ -1884,6 +1884,7 @@ def default_setting(name, new_default):
'_emscripten_tls_init',
'_pthread_self',
'_pthread_testcancel',
'_exit',
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Does adding to this list pin down the function from being DCEd if not used? exit() is not used always in pthreads builds?

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@sbc100 sbc100 Aug 26, 2021 •
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Yes, this entire like of functions cannot be DCEd in USE_PTHREADS builds.

However _exit is not special here. Just like all the other functions here is used by library_ptheads.js in general, but might be used in a given application. For example, imagine an application that builds with USE_PTHREADS but never actually creates in any threads.. all of the functions in this list would essentially be unused but also prevented from DCE.

I guess we want some other notion of EXPORTED_FUNCTIONS that also allows for DCE, but I don't know if that exists.

Perhaps we could add something like EXPORTED_FUNCTIONS_FOR_POSSIBLE_INTERNAL_JS_USAGE_ONLY?

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Or maybe just POSSIBLY_USED_FUNCTIONS?

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The reference to _exit is from the exitProcess handling code, and I wonder if we could if that out when EXIT_RUNTIME is not set... that would be a good solution I think. On the other hand the proc_exit library functions (of which exit is an alias) is just a single line of code on MINIMAL_RUNTIME and given that USE_PTHREADS brings in many hundreds of extra lines of code (IIUC) it maybe not that urgent to fix?

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Oh, I think I wrong, please ignore those previous replies.

Adding to EXPORTED_FUNCTIONS does not prevent DCE, because we don't consider them USER_EXPORTED_FUNCTIONS. Only USER_EXPORTED_FUNCTIONS are prevented from DCE.

]
# Some of these symbols are using by worker.js but otherwise unreferenced.
# Because emitDCEGraph only considered the main js file, and not worker.js
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9 changes: 7 additions & 2 deletions src/library_pthread.js
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Expand Up @@ -9,6 +9,7 @@ var LibraryPThread = {
$PThread__deps: ['_emscripten_thread_init',
'emscripten_futex_wake', '$killThread',
'$cancelThread', '$cleanupThread',
'exit',
#if !MINIMAL_RUNTIME
'$handleException',
#endif
Expand Down Expand Up @@ -57,7 +58,9 @@ var LibraryPThread = {
// things.
PThread['receiveObjectTransfer'] = PThread.receiveObjectTransfer;
PThread['threadInit'] = PThread.threadInit;
#if !MINIMAL_RUNTIME
PThread['setExitStatus'] = PThread.setExitStatus;
#endif
#endif
},
// Maps pthread_t to pthread info objects
Expand Down Expand Up @@ -130,9 +133,11 @@ var LibraryPThread = {
},
#endif

#if !MINIMAL_RUNTIME
setExitStatus: function(status) {
EXITSTATUS = status;
},
#endif

terminateAllThreads: function() {
for (var t in PThread.pthreads) {
Expand Down Expand Up @@ -305,10 +310,10 @@ var LibraryPThread = {
err("exitProcess requested by worker");
#endif
#if MINIMAL_RUNTIME
exit(d['returnCode']);
_exit(d['returnCode']);
#else
try {
exit(d['returnCode']);
_exit(d['returnCode']);
} catch (e) {
handleException(e);
}
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2 changes: 1 addition & 1 deletion src/minimal_runtime_worker_externs.js
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Expand Up @@ -4,7 +4,7 @@
* SPDX-License-Identifier: MIT
*/

// These externs are needed for MINIMAL_RUNTIME + USE_PTHREADS + !MODULARIZE
// These externs are needed for MINIMAL_RUNTIME + USE_PTHREADS
// This file should go away in the future when worker.js is refactored to live inside the JS module.

var ENVIRONMENT_IS_PTHREAD;
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2 changes: 1 addition & 1 deletion src/preamble_minimal.js
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Expand Up @@ -108,7 +108,7 @@ if (!ENVIRONMENT_IS_PTHREAD) {
#if USE_PTHREADS
} else {
#if MODULARIZE
updateGlobalBufferAndViews({{{EXPORT_NAME}}}.buffer);
updateGlobalBufferAndViews(Module.buffer);
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Why is this changed?

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Without this it fails closure compiler with MyModule not defined. I think this is because closure runs before modularization so at the point of closure compiler MyModule (the EXPORT_NAME) does not exist.

However Module.buffer works just fine here because the modularized code starts with

function(MyModule) {                                                             
  MyModule = MyModule || {};                                                     
                                                                                 
                                                                                 
                                                                                 
var Module = MyModule;

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I see, sounds good. And closure will remove the extra var anyhow.

#else
updateGlobalBufferAndViews(wasmMemory.buffer);
#endif
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6 changes: 2 additions & 4 deletions src/shell_minimal.js
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Expand Up @@ -32,7 +32,7 @@ var ENVIRONMENT_IS_NODE = typeof process === 'object';
var ENVIRONMENT_IS_SHELL = typeof read === 'function';
#endif

#if ASSERTIONS
#if ASSERTIONS || USE_PTHREADS
#if !ENVIRONMENT_MAY_BE_NODE && !ENVIRONMENT_MAY_BE_SHELL
var ENVIRONMENT_IS_WEB = true
#elif ENVIRONMENT && !ENVIRONMENT.includes(',')
Expand All @@ -43,10 +43,8 @@ var ENVIRONMENT_IS_WEB = !ENVIRONMENT_IS_NODE && !ENVIRONMENT_IS_SHELL;
var ENVIRONMENT_IS_WEB = !ENVIRONMENT_IS_SHELL;
#else
var ENVIRONMENT_IS_WEB = !ENVIRONMENT_IS_NODE;
#else

#endif
#endif // ASSERTIONS
#endif // ASSERTIONS || USE_PTHREADS

#if ASSERTIONS && ENVIRONMENT_MAY_BE_NODE && ENVIRONMENT_MAY_BE_SHELL
if (ENVIRONMENT_IS_NODE && ENVIRONMENT_IS_SHELL) {
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7 changes: 4 additions & 3 deletions tests/test_browser.py
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Expand Up @@ -4701,11 +4701,12 @@ def test_pthread_hello_thread(self, opts):
# Tests that a pthreads build of -s MINIMAL_RUNTIME=1 works well in different build modes
@parameterized({
'': ([],),
'O3': (['-O3'],)
'modularize': (['-sMODULARIZE', '-sEXPORT_NAME=MyModule'],),
'O3': (['-O3'],),
'O3_modularize': (['-O3', '-sMODULARIZE', '-sEXPORT_NAME=MyModule'],),
})
def test_minimal_runtime_hello_thread(self, opts):
for modularize in [[], ['-s', 'MODULARIZE', '-s', 'EXPORT_NAME=MyModule']]:
self.btest_exit(test_file('pthread/hello_thread.c'), expected='1', args=['-s', 'MINIMAL_RUNTIME', '-s', 'USE_PTHREADS'] + modularize + opts)
self.btest_exit(test_file('pthread/hello_thread.c'), expected='1', args=['--closure=1', '-sMINIMAL_RUNTIME', '-sUSE_PTHREADS'] + opts)

# Tests memory growth in pthreads mode, but still on the main thread.
@requires_threads
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2 changes: 1 addition & 1 deletion tools/building.py
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Expand Up @@ -823,7 +823,7 @@ def add_to_path(dirname):
if settings.DYNCALLS:
CLOSURE_EXTERNS += [path_from_root('src/closure-externs/dyncall-externs.js')]

if settings.MINIMAL_RUNTIME and settings.USE_PTHREADS and not settings.MODULARIZE:
if settings.MINIMAL_RUNTIME and settings.USE_PTHREADS:
CLOSURE_EXTERNS += [path_from_root('src/minimal_runtime_worker_externs.js')]

args = ['--compilation_level', 'ADVANCED_OPTIMIZATIONS' if advanced else 'SIMPLE_OPTIMIZATIONS']
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