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[builtins] Implement emulated TLS on Windows.
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Summary:
LLVM JIT needs to be able to use emulated TLS on all platforms, and this provides a reference one can compile to enable emutls for Linux/Mac/Windows.

Reviewers: chh, howard.hinnant

Reviewed By: chh

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D30787

llvm-svn: 301089
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Frederich Munch committed Apr 22, 2017
1 parent 3b863f8 commit 5de7f2d
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Showing 2 changed files with 222 additions and 67 deletions.
9 changes: 2 additions & 7 deletions compiler-rt/lib/builtins/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -164,7 +164,8 @@ set(GENERIC_SOURCES
udivti3.c
umoddi3.c
umodsi3.c
umodti3.c)
umodti3.c
emutls.c)

option(COMPILER_RT_EXCLUDE_ATOMIC_BUILTIN
"Skip the atomic builtin (this may be needed if system headers are unavailable)"
Expand All @@ -187,12 +188,6 @@ if(APPLE)
atomic_thread_fence.c)
endif()

if(NOT WIN32 OR MINGW)
set(GENERIC_SOURCES
${GENERIC_SOURCES}
emutls.c)
endif()

if (HAVE_UNWIND_H)
set(GENERIC_SOURCES
${GENERIC_SOURCES}
Expand Down
280 changes: 220 additions & 60 deletions compiler-rt/lib/builtins/emutls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -7,41 +7,38 @@
*
* ===----------------------------------------------------------------------===
*/
#include <pthread.h>

#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include "int_lib.h"
#include "int_util.h"

typedef struct emutls_address_array {
uintptr_t size; /* number of elements in the 'data' array */
void* data[];
} emutls_address_array;

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;

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

/* 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 unsigned int gcc_word __attribute__((mode(word)));
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;

static __inline void *emutls_memalign_alloc(size_t align, size_t size) {
void *base;
#if EMUTLS_USE_POSIX_MEMALIGN
Expand All @@ -50,7 +47,7 @@ static __inline void *emutls_memalign_alloc(size_t align, size_t size) {
#else
#define EXTRA_ALIGN_PTR_BYTES (align - 1 + sizeof(void*))
char* object;
if ((object = malloc(EXTRA_ALIGN_PTR_BYTES + size)) == NULL)
if ((object = (char*)malloc(EXTRA_ALIGN_PTR_BYTES + size)) == NULL)
abort();
base = (void*)(((uintptr_t)(object + EXTRA_ALIGN_PTR_BYTES))
& ~(uintptr_t)(align - 1));
Expand All @@ -69,10 +66,192 @@ static __inline void emutls_memalign_free(void *base) {
#endif
}

static void emutls_key_destructor(void* ptr) {
emutls_shutdown((emutls_address_array*)ptr);
free(ptr);
}

static __inline void emutls_init(void) {
if (pthread_key_create(&emutls_pthread_key, emutls_key_destructor) != 0)
abort();
}

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);
}

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);
}

#else

#include <Windows.h>
#include <malloc.h>
#include <stdio.h>
#include <assert.h>
#include <immintrin.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;
}

enum { __ATOMIC_ACQUIRE, __ATOMIC_RELEASE };

static __inline uintptr_t __atomic_load_n(void *ptr, unsigned type) {
assert(type == __ATOMIC_ACQUIRE);
return (uintptr_t) _load_be_u64(ptr);
}

static __inline void __atomic_store_n(void *ptr, uintptr_t val, unsigned type) {
assert(type == __ATOMIC_RELEASE);
_store_be_u64(ptr, val);
}
#pragma warning (pop)

#endif

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. */
typedef unsigned int gcc_pointer __attribute__((mode(pointer)));
COMPILE_TIME_ASSERT(sizeof(uintptr_t) == sizeof(gcc_pointer));
COMPILE_TIME_ASSERT(sizeof(uintptr_t) == sizeof(void*));

Expand All @@ -93,45 +272,19 @@ static __inline void *emutls_allocate_object(__emutls_control *control) {
return base;
}

static pthread_mutex_t emutls_mutex = PTHREAD_MUTEX_INITIALIZER;

static size_t emutls_num_object = 0; /* number of allocated TLS objects */

typedef struct emutls_address_array {
uintptr_t size; /* number of elements in the 'data' array */
void* data[];
} emutls_address_array;

static pthread_key_t emutls_pthread_key;

static void emutls_key_destructor(void* ptr) {
emutls_address_array* array = (emutls_address_array*)ptr;
uintptr_t i;
for (i = 0; i < array->size; ++i) {
if (array->data[i])
emutls_memalign_free(array->data[i]);
}
free(ptr);
}

static void emutls_init(void) {
if (pthread_key_create(&emutls_pthread_key, emutls_key_destructor) != 0)
abort();
}

/* 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) {
static pthread_once_t once = PTHREAD_ONCE_INIT;
pthread_once(&once, emutls_init);
pthread_mutex_lock(&emutls_mutex);
emutls_init_once();
emutls_lock();
index = control->object.index;
if (!index) {
index = ++emutls_num_object;
__atomic_store_n(&control->object.index, index, __ATOMIC_RELEASE);
}
pthread_mutex_unlock(&emutls_mutex);
emutls_unlock();
}
return index;
}
Expand All @@ -142,7 +295,7 @@ static __inline void emutls_check_array_set_size(emutls_address_array *array,
if (array == NULL)
abort();
array->size = size;
pthread_setspecific(emutls_pthread_key, (void*)array);
emutls_setspecific(array);
}

/* Returns the new 'data' array size, number of elements,
Expand All @@ -156,22 +309,29 @@ static __inline uintptr_t emutls_new_data_array_size(uintptr_t index) {
return ((index + 1 + 15) & ~((uintptr_t)15)) - 1;
}

/* 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 = pthread_getspecific(emutls_pthread_key);
emutls_address_array* array = emutls_getspecific();
if (array == NULL) {
uintptr_t new_size = emutls_new_data_array_size(index);
array = malloc(new_size * sizeof(void *) + sizeof(emutls_address_array));
array = (emutls_address_array*) malloc(emutls_asize(new_size));
if (array)
memset(array->data, 0, new_size * sizeof(void*));
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 = realloc(array, new_size * sizeof(void *) + sizeof(emutls_address_array));
array = (emutls_address_array*) realloc(array, emutls_asize(new_size));
if (array)
memset(array->data + orig_size, 0,
(new_size - orig_size) * sizeof(void*));
Expand All @@ -182,8 +342,8 @@ emutls_get_address_array(uintptr_t index) {

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 - 1] == NULL)
array->data[index - 1] = emutls_allocate_object(control);
return array->data[index - 1];
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];
}

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