1 files changed, 394 insertions, 0 deletions
diff --git a/compiler-rt/lib/builtins/emutls.c b/compiler-rt/lib/builtins/emutls.c
new file mode 100644
index 000000000000..e0aa19155f7d
--- /dev/null
+++ b/compiler-rt/lib/builtins/emutls.c
@@ -0,0 +1,394 @@
+//===---------- emutls.c - Implements __emutls_get_address ---------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "int_lib.h"
+
+#ifdef __BIONIC__
+// There are 4 pthread key cleanup rounds on Bionic. Delay emutls deallocation
+// to round 2. We need to delay deallocation because:
+//  - Android versions older than M lack __cxa_thread_atexit_impl, so apps
+//    use a pthread key destructor to call C++ destructors.
+//  - Apps might use __thread/thread_local variables in pthread destructors.
+// We can't wait until the final two rounds, because jemalloc needs two rounds
+// after the final malloc/free call to free its thread-specific data (see
+// https://reviews.llvm.org/D46978#1107507).
+#define EMUTLS_SKIP_DESTRUCTOR_ROUNDS 1
+#else
+#define EMUTLS_SKIP_DESTRUCTOR_ROUNDS 0
+#endif
+
+#if defined(_MSC_VER) && !defined(__clang__)
+// MSVC raises a warning about a nonstandard extension being used for the 0
+// sized element in this array. Disable this for warn-as-error builds.
+#pragma warning(push)
+#pragma warning(disable : 4206)
+#endif
+
+typedef struct emutls_address_array {
+  uintptr_t skip_destructor_rounds;
+  uintptr_t size; // number of elements in the 'data' array
+  void *data[];
+} emutls_address_array;
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#endif
+
+static void emutls_shutdown(emutls_address_array *array);
+
+#ifndef _WIN32
+
+#include <pthread.h>
+
+static pthread_mutex_t emutls_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_key_t emutls_pthread_key;
+static bool emutls_key_created = false;
+
+typedef unsigned int gcc_word __attribute__((mode(word)));
+typedef unsigned int gcc_pointer __attribute__((mode(pointer)));
+
+// Default is not to use posix_memalign, so systems like Android
+// can use thread local data without heavier POSIX memory allocators.
+#ifndef EMUTLS_USE_POSIX_MEMALIGN
+#define EMUTLS_USE_POSIX_MEMALIGN 0
+#endif
+
+static __inline void *emutls_memalign_alloc(size_t align, size_t size) {
+  void *base;
+#if EMUTLS_USE_POSIX_MEMALIGN
+  if (posix_memalign(&base, align, size) != 0)
+    abort();
+#else
+#define EXTRA_ALIGN_PTR_BYTES (align - 1 + sizeof(void *))
+  char *object;
+  if ((object = (char *)malloc(EXTRA_ALIGN_PTR_BYTES + size)) == NULL)
+    abort();
+  base = (void *)(((uintptr_t)(object + EXTRA_ALIGN_PTR_BYTES)) &
+                  ~(uintptr_t)(align - 1));
+
+  ((void **)base)[-1] = object;
+#endif
+  return base;
+}
+
+static __inline void emutls_memalign_free(void *base) {
+#if EMUTLS_USE_POSIX_MEMALIGN
+  free(base);
+#else
+  // The mallocated address is in ((void**)base)[-1]
+  free(((void **)base)[-1]);
+#endif
+}
+
+static __inline void emutls_setspecific(emutls_address_array *value) {
+  pthread_setspecific(emutls_pthread_key, (void *)value);
+}
+
+static __inline emutls_address_array *emutls_getspecific() {
+  return (emutls_address_array *)pthread_getspecific(emutls_pthread_key);
+}
+
+static void emutls_key_destructor(void *ptr) {
+  emutls_address_array *array = (emutls_address_array *)ptr;
+  if (array->skip_destructor_rounds > 0) {
+    // emutls is deallocated using a pthread key destructor. These
+    // destructors are called in several rounds to accommodate destructor
+    // functions that (re)initialize key values with pthread_setspecific.
+    // Delay the emutls deallocation to accommodate other end-of-thread
+    // cleanup tasks like calling thread_local destructors (e.g. the
+    // __cxa_thread_atexit fallback in libc++abi).
+    array->skip_destructor_rounds--;
+    emutls_setspecific(array);
+  } else {
+    emutls_shutdown(array);
+    free(ptr);
+  }
+}
+
+static __inline void emutls_init(void) {
+  if (pthread_key_create(&emutls_pthread_key, emutls_key_destructor) != 0)
+    abort();
+  emutls_key_created = true;
+}
+
+static __inline void emutls_init_once(void) {
+  static pthread_once_t once = PTHREAD_ONCE_INIT;
+  pthread_once(&once, emutls_init);
+}
+
+static __inline void emutls_lock() { pthread_mutex_lock(&emutls_mutex); }
+
+static __inline void emutls_unlock() { pthread_mutex_unlock(&emutls_mutex); }
+
+#else // _WIN32
+
+#include <assert.h>
+#include <malloc.h>
+#include <stdio.h>
+#include <windows.h>
+
+static LPCRITICAL_SECTION emutls_mutex;
+static DWORD emutls_tls_index = TLS_OUT_OF_INDEXES;
+
+typedef uintptr_t gcc_word;
+typedef void *gcc_pointer;
+
+static void win_error(DWORD last_err, const char *hint) {
+  char *buffer = NULL;
+  if (FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER |
+                         FORMAT_MESSAGE_FROM_SYSTEM |
+                         FORMAT_MESSAGE_MAX_WIDTH_MASK,
+                     NULL, last_err, 0, (LPSTR)&buffer, 1, NULL)) {
+    fprintf(stderr, "Windows error: %s\n", buffer);
+  } else {
+    fprintf(stderr, "Unkown Windows error: %s\n", hint);
+  }
+  LocalFree(buffer);
+}
+
+static __inline void win_abort(DWORD last_err, const char *hint) {
+  win_error(last_err, hint);
+  abort();
+}
+
+static __inline void *emutls_memalign_alloc(size_t align, size_t size) {
+  void *base = _aligned_malloc(size, align);
+  if (!base)
+    win_abort(GetLastError(), "_aligned_malloc");
+  return base;
+}
+
+static __inline void emutls_memalign_free(void *base) { _aligned_free(base); }
+
+static void emutls_exit(void) {
+  if (emutls_mutex) {
+    DeleteCriticalSection(emutls_mutex);
+    _aligned_free(emutls_mutex);
+    emutls_mutex = NULL;
+  }
+  if (emutls_tls_index != TLS_OUT_OF_INDEXES) {
+    emutls_shutdown((emutls_address_array *)TlsGetValue(emutls_tls_index));
+    TlsFree(emutls_tls_index);
+    emutls_tls_index = TLS_OUT_OF_INDEXES;
+  }
+}
+
+#pragma warning(push)
+#pragma warning(disable : 4100)
+static BOOL CALLBACK emutls_init(PINIT_ONCE p0, PVOID p1, PVOID *p2) {
+  emutls_mutex =
+      (LPCRITICAL_SECTION)_aligned_malloc(sizeof(CRITICAL_SECTION), 16);
+  if (!emutls_mutex) {
+    win_error(GetLastError(), "_aligned_malloc");
+    return FALSE;
+  }
+  InitializeCriticalSection(emutls_mutex);
+
+  emutls_tls_index = TlsAlloc();
+  if (emutls_tls_index == TLS_OUT_OF_INDEXES) {
+    emutls_exit();
+    win_error(GetLastError(), "TlsAlloc");
+    return FALSE;
+  }
+  atexit(&emutls_exit);
+  return TRUE;
+}
+
+static __inline void emutls_init_once(void) {
+  static INIT_ONCE once;
+  InitOnceExecuteOnce(&once, emutls_init, NULL, NULL);
+}
+
+static __inline void emutls_lock() { EnterCriticalSection(emutls_mutex); }
+
+static __inline void emutls_unlock() { LeaveCriticalSection(emutls_mutex); }
+
+static __inline void emutls_setspecific(emutls_address_array *value) {
+  if (TlsSetValue(emutls_tls_index, (LPVOID)value) == 0)
+    win_abort(GetLastError(), "TlsSetValue");
+}
+
+static __inline emutls_address_array *emutls_getspecific() {
+  LPVOID value = TlsGetValue(emutls_tls_index);
+  if (value == NULL) {
+    const DWORD err = GetLastError();
+    if (err != ERROR_SUCCESS)
+      win_abort(err, "TlsGetValue");
+  }
+  return (emutls_address_array *)value;
+}
+
+// Provide atomic load/store functions for emutls_get_index if built with MSVC.
+#if !defined(__ATOMIC_RELEASE)
+#include <intrin.h>
+
+enum { __ATOMIC_ACQUIRE = 2, __ATOMIC_RELEASE = 3 };
+
+static __inline uintptr_t __atomic_load_n(void *ptr, unsigned type) {
+  assert(type == __ATOMIC_ACQUIRE);
+  // These return the previous value - but since we do an OR with 0,
+  // it's equivalent to a plain load.
+#ifdef _WIN64
+  return InterlockedOr64(ptr, 0);
+#else
+  return InterlockedOr(ptr, 0);
+#endif
+}
+
+static __inline void __atomic_store_n(void *ptr, uintptr_t val, unsigned type) {
+  assert(type == __ATOMIC_RELEASE);
+  InterlockedExchangePointer((void *volatile *)ptr, (void *)val);
+}
+
+#endif // __ATOMIC_RELEASE
+
+#pragma warning(pop)
+
+#endif // _WIN32
+
+static size_t emutls_num_object = 0; // number of allocated TLS objects
+
+// Free the allocated TLS data
+static void emutls_shutdown(emutls_address_array *array) {
+  if (array) {
+    uintptr_t i;
+    for (i = 0; i < array->size; ++i) {
+      if (array->data[i])
+        emutls_memalign_free(array->data[i]);
+    }
+  }
+}
+
+// For every TLS variable xyz,
+// there is one __emutls_control variable named __emutls_v.xyz.
+// If xyz has non-zero initial value, __emutls_v.xyz's "value"
+// will point to __emutls_t.xyz, which has the initial value.
+typedef struct __emutls_control {
+  // Must use gcc_word here, instead of size_t, to match GCC.  When
+  // gcc_word is larger than size_t, the upper extra bits are all
+  // zeros.  We can use variables of size_t to operate on size and
+  // align.
+  gcc_word size;  // size of the object in bytes
+  gcc_word align; // alignment of the object in bytes
+  union {
+    uintptr_t index; // data[index-1] is the object address
+    void *address;   // object address, when in single thread env
+  } object;
+  void *value; // null or non-zero initial value for the object
+} __emutls_control;
+
+// Emulated TLS objects are always allocated at run-time.
+static __inline void *emutls_allocate_object(__emutls_control *control) {
+  // Use standard C types, check with gcc's emutls.o.
+  COMPILE_TIME_ASSERT(sizeof(uintptr_t) == sizeof(gcc_pointer));
+  COMPILE_TIME_ASSERT(sizeof(uintptr_t) == sizeof(void *));
+
+  size_t size = control->size;
+  size_t align = control->align;
+  void *base;
+  if (align < sizeof(void *))
+    align = sizeof(void *);
+  // Make sure that align is power of 2.
+  if ((align & (align - 1)) != 0)
+    abort();
+
+  base = emutls_memalign_alloc(align, size);
+  if (control->value)
+    memcpy(base, control->value, size);
+  else
+    memset(base, 0, size);
+  return base;
+}
+
+// Returns control->object.index; set index if not allocated yet.
+static __inline uintptr_t emutls_get_index(__emutls_control *control) {
+  uintptr_t index = __atomic_load_n(&control->object.index, __ATOMIC_ACQUIRE);
+  if (!index) {
+    emutls_init_once();
+    emutls_lock();
+    index = control->object.index;
+    if (!index) {
+      index = ++emutls_num_object;
+      __atomic_store_n(&control->object.index, index, __ATOMIC_RELEASE);
+    }
+    emutls_unlock();
+  }
+  return index;
+}
+
+// Updates newly allocated thread local emutls_address_array.
+static __inline void emutls_check_array_set_size(emutls_address_array *array,
+                                                 uintptr_t size) {
+  if (array == NULL)
+    abort();
+  array->size = size;
+  emutls_setspecific(array);
+}
+
+// Returns the new 'data' array size, number of elements,
+// which must be no smaller than the given index.
+static __inline uintptr_t emutls_new_data_array_size(uintptr_t index) {
+  // Need to allocate emutls_address_array with extra slots
+  // to store the header.
+  // Round up the emutls_address_array size to multiple of 16.
+  uintptr_t header_words = sizeof(emutls_address_array) / sizeof(void *);
+  return ((index + header_words + 15) & ~((uintptr_t)15)) - header_words;
+}
+
+// Returns the size in bytes required for an emutls_address_array with
+// N number of elements for data field.
+static __inline uintptr_t emutls_asize(uintptr_t N) {
+  return N * sizeof(void *) + sizeof(emutls_address_array);
+}
+
+// Returns the thread local emutls_address_array.
+// Extends its size if necessary to hold address at index.
+static __inline emutls_address_array *
+emutls_get_address_array(uintptr_t index) {
+  emutls_address_array *array = emutls_getspecific();
+  if (array == NULL) {
+    uintptr_t new_size = emutls_new_data_array_size(index);
+    array = (emutls_address_array *)malloc(emutls_asize(new_size));
+    if (array) {
+      memset(array->data, 0, new_size * sizeof(void *));
+      array->skip_destructor_rounds = EMUTLS_SKIP_DESTRUCTOR_ROUNDS;
+    }
+    emutls_check_array_set_size(array, new_size);
+  } else if (index > array->size) {
+    uintptr_t orig_size = array->size;
+    uintptr_t new_size = emutls_new_data_array_size(index);
+    array = (emutls_address_array *)realloc(array, emutls_asize(new_size));
+    if (array)
+      memset(array->data + orig_size, 0,
+             (new_size - orig_size) * sizeof(void *));
+    emutls_check_array_set_size(array, new_size);
+  }
+  return array;
+}
+
+void *__emutls_get_address(__emutls_control *control) {
+  uintptr_t index = emutls_get_index(control);
+  emutls_address_array *array = emutls_get_address_array(index--);
+  if (array->data[index] == NULL)
+    array->data[index] = emutls_allocate_object(control);
+  return array->data[index];
+}
+
+#ifdef __BIONIC__
+// Called by Bionic on dlclose to delete the emutls pthread key.
+__attribute__((visibility("hidden"))) void __emutls_unregister_key(void) {
+  if (emutls_key_created) {
+    pthread_key_delete(emutls_pthread_key);
+    emutls_key_created = false;
+  }
+}
+#endif