Split the pthread library out of libc. NFC

Author: sbc100

ChangeLog.md

@@ -34,6 +34,9 @@ See docs/process.md for more on how version tagging works.
   on by default, but now it cannot be disabled.  This setting was originally
   added in 2019 as a temporary measure while engines and bundlers learned to
   deal with `import.meta`. (#23171)
+- The pthread functions now live in a separate libpthread (or libpthread-stub).
+  This library is automatically included so this change will only effect those
+  building with `-nostdlib` or `-nolibc`. (#22735)
 
 4.0.3 - 02/07/25
 ----------------

embuilder.py

@@ -75,6 +75,10 @@
     'libGL-webgl2-ofb-getprocaddr',
     'libGL-ww-getprocaddr',
     'libhtml5',
+    'libpthread',
+    'libpthread-stub',
+    'libpthread-debug',
+    'libpthread-debug-stub',
     'libsockets',
     'libsockets-ww',
     'libstubs',

test/test_core.py

@@ -4614,10 +4614,10 @@ def test_dylink_postsets_chunking(self):
 
   @with_dylink_reversed
   @parameterized({
-    'libcxx': ('libc,libc++,libmalloc,libc++abi',),
+    'libcxx': ('libc,libpthread,libc++,libmalloc,libc++abi',),
     'all': ('1',),
-    'missing': ('libc,libmalloc,libc++abi', False, False, False),
-    'missing_assertions': ('libc,libmalloc,libc++abi', False, False, True),
+    'missing': ('libc,libpthread,libmalloc,libc++abi', False, False, False),
+    'missing_assertions': ('libc,libpthread,libmalloc,libc++abi', False, False, True),
   })
   def test_dylink_syslibs(self, syslibs, expect_pass=True, with_reversed=True, assertions=True):
     # one module uses libcxx, need to force its inclusion when it isn't the main

test/test_other.py

@@ -6293,9 +6293,9 @@ def test_fs_dev_random(self):
     # partial list, but ok since we grab them as needed
     'parial': [{'EMCC_FORCE_STDLIBS': 'libc++'}, False],
     # fail! not enough stdlibs
-    'partial_only': [{'EMCC_FORCE_STDLIBS': 'libc++,libc,libc++abi', 'EMCC_ONLY_FORCED_STDLIBS': '1'}, True],
+    'partial_only': [{'EMCC_FORCE_STDLIBS': 'libc++,libc,libpthread,libc++abi', 'EMCC_ONLY_FORCED_STDLIBS': '1'}, True],
     # force all the needed stdlibs, so this works even though we ignore the input file
-    'full_only': [{'EMCC_FORCE_STDLIBS': 'libc,libc++abi,libc++,libmalloc', 'EMCC_ONLY_FORCED_STDLIBS': '1'}, False],
+    'full_only': [{'EMCC_FORCE_STDLIBS': 'libc,libpthread,libc++abi,libc++,libmalloc', 'EMCC_ONLY_FORCED_STDLIBS': '1'}, False],
   })
   def test_only_force_stdlibs(self, env, fail):
     cmd = [EMXX, test_file('hello_libcxx.cpp')]
@@ -6326,7 +6326,7 @@ def test_only_force_stdlibs_2(self):
   }
 }
 ''')
-    with env_modify({'EMCC_FORCE_STDLIBS': 'libc,libc++abi,libc++,libmalloc', 'EMCC_ONLY_FORCED_STDLIBS': '1'}):
+    with env_modify({'EMCC_FORCE_STDLIBS': 'libc,libpthread,libc++abi,libc++,libmalloc', 'EMCC_ONLY_FORCED_STDLIBS': '1'}):
       self.run_process([EMXX, 'src.cpp', '-sDISABLE_EXCEPTION_CATCHING=0'])
     self.assertContained('Caught exception: std::exception', self.run_js('a.out.js'))
 
@@ -12758,10 +12758,10 @@ def test_nostdlib(self):
     self.assertContained(err, self.expect_fail([EMCC, test_file('unistd/close.c'), '-nodefaultlibs']))
 
     # Build again but with explit system libraries
-    libs = ['-lc', '-lcompiler_rt']
+    libs = ['-lc', '-lpthread', '-lcompiler_rt']
     self.run_process([EMCC, test_file('unistd/close.c'), '-nostdlib'] + libs)
     self.run_process([EMCC, test_file('unistd/close.c'), '-nodefaultlibs'] + libs)
-    self.run_process([EMCC, test_file('unistd/close.c'), '-nolibc', '-lc'])
+    self.run_process([EMCC, test_file('unistd/close.c'), '-nolibc', '-lc', '-lpthread'])
     self.run_process([EMCC, test_file('unistd/close.c'), '-nostartfiles'])
 
   def test_argument_match(self):
@@ -13619,12 +13619,13 @@ def test_offset_convertor_plus_wasm2js(self):
 
   def test_standard_library_mapping(self):
     # Test the `-l` flags on the command line get mapped the correct libraries variant
-    libs = ['-lc', '-lcompiler_rt', '-lmalloc']
+    libs = ['-lc', '-lpthread', '-lcompiler_rt', '-lmalloc']
     err = self.run_process([EMCC, test_file('hello_world.c'), '-pthread', '-nodefaultlibs', '-v'] + libs, stderr=PIPE).stderr
 
     # Check that the linker was run with `-mt` variants because `-pthread` was passed.
     self.assertContained(' -lc-mt-debug ', err)
     self.assertContained(' -ldlmalloc-mt-debug ', err)
+    self.assertContained(' -lpthread-debug ', err)
     self.assertContained(' -lcompiler_rt-mt ', err)
 
   def test_explicit_gl_linking(self):

tools/link.py

@@ -2752,7 +2752,6 @@ def map_to_js_libs(library_name):
     'dl': [],
     'm': [],
     'rt': [],
-    'pthread': [],
     # This is the name of GNU's C++ standard library. We ignore it here
     # for compatibility with GNU toolchains.
     'stdc++': [],

tools/system_libs.py

@@ -984,6 +984,138 @@ class libnoexit(Library):
   src_files = ['atexit_dummy.c']
 
 
+class libpthread(MuslInternalLibrary,
+                 DebugLibrary,
+                 AsanInstrumentedLibrary):
+  name = 'libpthread'
+  # See libc
+  cflags = ['-Os', '-fno-inline-functions', '-fno-builtin']
+  cflags += ['-Wno-unused-but-set-variable',
+             '-Wno-unused-variable',
+             '-Wno-shift-op-parentheses',
+             '-Wno-unused-label',
+             '-Wno-logical-op-parentheses',
+             '-Wno-bitwise-op-parentheses']
+
+  def __init__(self, **kwargs):
+    self.is_stub = kwargs.pop('stub')
+    super().__init__(**kwargs)
+
+  def get_cflags(self):
+    cflags = super().get_cflags()
+    if not self.is_stub:
+      cflags += ['-pthread']
+    return cflags
+
+  def get_base_name(self):
+    name = super().get_base_name()
+    if self.is_stub:
+      name += '-stub'
+    return name
+
+  @classmethod
+  def vary_on(cls):
+    return super().vary_on() + ['stub']
+
+  @classmethod
+  def get_default_variation(cls, **kwargs):
+    return super().get_default_variation(stub=not settings.PTHREADS, **kwargs)
+
+  def get_files(self):
+    files = files_in_path(
+        path='system/lib/pthread',
+        filenames=['thread_profiler.c'])
+
+    if self.is_stub:
+      # Include just a subset of the thread directory
+      files += files_in_path(
+        path='system/lib/libc/musl/src/thread',
+        filenames=[
+          'pthread_self.c',
+          'pthread_cleanup_push.c',
+          'pthread_attr_init.c',
+          'pthread_attr_destroy.c',
+          'pthread_attr_get.c',
+          'pthread_attr_setdetachstate.c',
+          'pthread_attr_setguardsize.c',
+          'pthread_attr_setinheritsched.c',
+          'pthread_attr_setschedparam.c',
+          'pthread_attr_setschedpolicy.c',
+          'pthread_attr_setscope.c',
+          'pthread_attr_setstack.c',
+          'pthread_attr_setstacksize.c',
+          'pthread_getconcurrency.c',
+          'pthread_getcpuclockid.c',
+          'pthread_getschedparam.c',
+          'pthread_setschedprio.c',
+          'pthread_setconcurrency.c',
+          'default_attr.c',
+          # C11 thread library functions
+          'call_once.c',
+          'tss_create.c',
+          'tss_delete.c',
+          'tss_set.c',
+          'cnd_broadcast.c',
+          'cnd_destroy.c',
+          'cnd_init.c',
+          'cnd_signal.c',
+          'cnd_timedwait.c',
+          'cnd_wait.c',
+          'mtx_destroy.c',
+          'mtx_init.c',
+          'mtx_lock.c',
+          'mtx_timedlock.c',
+          'mtx_trylock.c',
+          'mtx_unlock.c',
+          'thrd_create.c',
+          'thrd_exit.c',
+          'thrd_join.c',
+          'thrd_sleep.c',
+          'thrd_yield.c',
+        ])
+      files += files_in_path(
+        path='system/lib/pthread',
+        filenames=[
+          'library_pthread_stub.c',
+          'pthread_self_stub.c',
+          'proxying_stub.c',
+        ])
+    else:
+      files += glob_in_path(
+        path='system/lib/libc/musl/src/thread',
+        glob_pattern='*.c',
+        excludes=[
+          'clone.c',
+          'pthread_create.c',
+          'pthread_kill.c', 'pthread_sigmask.c',
+          '__set_thread_area.c', 'synccall.c',
+          '__syscall_cp.c', '__tls_get_addr.c',
+          '__unmapself.c',
+          # Empty files, simply ignore them.
+          'syscall_cp.c', 'tls.c',
+          # TODO: Support these. See #12216.
+          'pthread_setname_np.c',
+          'pthread_getname_np.c',
+        ])
+      files += files_in_path(
+        path='system/lib/pthread',
+        filenames=[
+          'library_pthread.c',
+          'em_task_queue.c',
+          'proxying.c',
+          'proxying_legacy.c',
+          'thread_mailbox.c',
+          'pthread_create.c',
+          'pthread_kill.c',
+          'emscripten_thread_init.c',
+          'emscripten_thread_state.S',
+          'emscripten_futex_wait.c',
+          'emscripten_futex_wake.c',
+          'emscripten_yield.c',
+        ])
+    return files
+
+
 class libc(MuslInternalLibrary,
            DebugLibrary,
            AsanInstrumentedLibrary,
@@ -1098,7 +1230,7 @@ def get_files(self):
     ignore = [
         'ipc', 'passwd', 'signal', 'sched', 'time', 'linux',
         'aio', 'exit', 'legacy', 'mq', 'setjmp',
-        'ldso', 'malloc'
+        'ldso', 'malloc', 'thread'
     ]
 
     # individual files
@@ -1120,91 +1252,6 @@ def get_files(self):
 
     ignore += LIBC_SOCKETS
 
-    if self.is_mt:
-      ignore += [
-        'clone.c',
-        'pthread_create.c',
-        'pthread_kill.c', 'pthread_sigmask.c',
-        '__set_thread_area.c', 'synccall.c',
-        '__syscall_cp.c', '__tls_get_addr.c',
-        '__unmapself.c',
-        # Empty files, simply ignore them.
-        'syscall_cp.c', 'tls.c',
-        # TODO: Support these. See #12216.
-        'pthread_setname_np.c',
-        'pthread_getname_np.c',
-      ]
-      libc_files += files_in_path(
-        path='system/lib/pthread',
-        filenames=[
-          'library_pthread.c',
-          'em_task_queue.c',
-          'proxying.c',
-          'proxying_legacy.c',
-          'thread_mailbox.c',
-          'pthread_create.c',
-          'pthread_kill.c',
-          'emscripten_thread_init.c',
-          'emscripten_thread_state.S',
-          'emscripten_futex_wait.c',
-          'emscripten_futex_wake.c',
-          'emscripten_yield.c',
-        ])
-    else:
-      ignore += ['thread']
-      libc_files += files_in_path(
-        path='system/lib/libc/musl/src/thread',
-        filenames=[
-          'pthread_self.c',
-          'pthread_cleanup_push.c',
-          'pthread_attr_init.c',
-          'pthread_attr_destroy.c',
-          'pthread_attr_get.c',
-          'pthread_attr_setdetachstate.c',
-          'pthread_attr_setguardsize.c',
-          'pthread_attr_setinheritsched.c',
-          'pthread_attr_setschedparam.c',
-          'pthread_attr_setschedpolicy.c',
-          'pthread_attr_setscope.c',
-          'pthread_attr_setstack.c',
-          'pthread_attr_setstacksize.c',
-          'pthread_getconcurrency.c',
-          'pthread_getcpuclockid.c',
-          'pthread_getschedparam.c',
-          'pthread_setschedprio.c',
-          'pthread_setconcurrency.c',
-          'default_attr.c',
-          # C11 thread library functions
-          'call_once.c',
-          'tss_create.c',
-          'tss_delete.c',
-          'tss_set.c',
-          'cnd_broadcast.c',
-          'cnd_destroy.c',
-          'cnd_init.c',
-          'cnd_signal.c',
-          'cnd_timedwait.c',
-          'cnd_wait.c',
-          'mtx_destroy.c',
-          'mtx_init.c',
-          'mtx_lock.c',
-          'mtx_timedlock.c',
-          'mtx_trylock.c',
-          'mtx_unlock.c',
-          'thrd_create.c',
-          'thrd_exit.c',
-          'thrd_join.c',
-          'thrd_sleep.c',
-          'thrd_yield.c',
-        ])
-      libc_files += files_in_path(
-        path='system/lib/pthread',
-        filenames=[
-          'library_pthread_stub.c',
-          'pthread_self_stub.c',
-          'proxying_stub.c',
-        ])
-
     # These files are in libc directories, but only built in libc_optz.
     ignore += [
       'pow_small.c', 'log_small.c', 'log2_small.c'
@@ -1322,10 +1369,6 @@ def get_files(self):
     if settings.RELOCATABLE:
       libc_files += files_in_path(path='system/lib/libc', filenames=['dynlink.c'])
 
-    libc_files += files_in_path(
-        path='system/lib/pthread',
-        filenames=['thread_profiler.c'])
-
     libc_files += glob_in_path('system/lib/libc/compat', '*.c')
 
     # Check for missing file in non_lto_files list.  Do this here
@@ -2378,6 +2421,7 @@ def add_sanitizer_libs():
   if settings.ALLOW_UNIMPLEMENTED_SYSCALLS:
     add_library('libstubs')
   if not options.nolibc:
+    add_library('libpthread')
     if not settings.EXIT_RUNTIME:
       add_library('libnoexit')
     add_library('libc')