Avoid static allocations in pthreads code (#12055)

Just replaces some static allocations with mallocs that are never
freed. Optimally these could be actually static allocations in C in a
future refactoring perhaps.

Author: kripken

src/library_pthread.js

@@ -8,7 +8,12 @@ var LibraryPThread = {
   $PThread__postset: 'if (!ENVIRONMENT_IS_PTHREAD) PThread.initMainThreadBlock(); else PThread.initWorker();',
   $PThread__deps: ['$registerPthreadPtr',
                    '$ERRNO_CODES', 'emscripten_futex_wake', '$killThread',
-                   '$cancelThread', '$cleanupThread'],
+                   '$cancelThread', '$cleanupThread',
+                   '_main_thread_futex_wait_address'
+#if USE_ASAN || USE_LSAN
+                   , '$withBuiltinMalloc'
+#endif
+                   ],
   $PThread: {
     MAIN_THREAD_ID: 1, // A special constant that identifies the main JS thread ID.
     mainThreadInfo: {
@@ -37,7 +42,15 @@ var LibraryPThread = {
 #endif
     },
     initRuntime: function() {
-      PThread.mainThreadBlock = {{{ makeStaticAlloc(C_STRUCTS.pthread.__size__) }}};
+#if USE_ASAN || USE_LSAN
+      // When sanitizers are enabled, malloc is normally instrumented to call
+      // sanitizer code that checks some things about pthreads. As we are just
+      // setting up the main thread here, and are not ready for such calls,
+      // call malloc directly.
+      withBuiltinMalloc(function () {
+#endif
+
+      PThread.mainThreadBlock = _malloc({{{ C_STRUCTS.pthread.__size__ }}});
 
       for (var i = 0; i < {{{ C_STRUCTS.pthread.__size__ }}}/4; ++i) HEAPU32[PThread.mainThreadBlock/4+i] = 0;
 
@@ -50,18 +63,24 @@ var LibraryPThread = {
       {{{ makeSetValue('headPtr', 0, 'headPtr', 'i32') }}};
 
       // Allocate memory for thread-local storage.
-      var tlsMemory = {{{ makeStaticAlloc(cDefine('PTHREAD_KEYS_MAX') * 4) }}};
+      var tlsMemory = _malloc({{{ cDefine('PTHREAD_KEYS_MAX') * 4 }}});
       for (var i = 0; i < {{{ cDefine('PTHREAD_KEYS_MAX') }}}; ++i) HEAPU32[tlsMemory/4+i] = 0;
       Atomics.store(HEAPU32, (PThread.mainThreadBlock + {{{ C_STRUCTS.pthread.tsd }}} ) >> 2, tlsMemory); // Init thread-local-storage memory array.
       Atomics.store(HEAPU32, (PThread.mainThreadBlock + {{{ C_STRUCTS.pthread.tid }}} ) >> 2, PThread.mainThreadBlock); // Main thread ID.
       Atomics.store(HEAPU32, (PThread.mainThreadBlock + {{{ C_STRUCTS.pthread.pid }}} ) >> 2, {{{ PROCINFO.pid }}}); // Process ID.
 
+      __main_thread_futex_wait_address = _malloc(4);
+
 #if PTHREADS_PROFILING
       PThread.createProfilerBlock(PThread.mainThreadBlock);
       PThread.setThreadName(PThread.mainThreadBlock, "Browser main thread");
       PThread.setThreadStatus(PThread.mainThreadBlock, {{{ cDefine('EM_THREAD_STATUS_RUNNING') }}});
 #endif
 
+#if USE_ASAN || USE_LSAN
+      });
+#endif
+
       // Pass the thread address inside the asm.js scope to store it for fast access that avoids the need for a FFI out.
       // Global constructors trying to access this value will read the wrong value, but that is UB anyway.
       registerPthreadPtr(PThread.mainThreadBlock, /*isMainBrowserThread=*/!ENVIRONMENT_IS_WORKER, /*isMainRuntimeThread=*/1);
@@ -83,7 +102,7 @@ var LibraryPThread = {
 
 #if PTHREADS_PROFILING
     createProfilerBlock: function(pthreadPtr) {
-      var profilerBlock = (pthreadPtr == PThread.mainThreadBlock) ? {{{ makeStaticAlloc(C_STRUCTS.thread_profiler_block.__size__) }}} : _malloc({{{ C_STRUCTS.thread_profiler_block.__size__ }}});
+      var profilerBlock = _malloc({{{ C_STRUCTS.thread_profiler_block.__size__ }}});
       Atomics.store(HEAPU32, (pthreadPtr + {{{ C_STRUCTS.pthread.profilerBlock }}} ) >> 2, profilerBlock);
 
       // Zero fill contents at startup.
@@ -1094,7 +1113,7 @@ var LibraryPThread = {
   },
 
   // Stores the memory address that the main thread is waiting on, if any.
-  _main_thread_futex_wait_address: '{{{ makeStaticAlloc(4) }}}',
+  _main_thread_futex_wait_address: '0',
 
   // Returns 0 on success, or one of the values -ETIMEDOUT, -EWOULDBLOCK or -EINVAL on error.
   emscripten_futex_wait__deps: ['_main_thread_futex_wait_address', 'emscripten_main_thread_process_queued_calls'],