GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcompiler_rt/emutls.c Lines: 0 60 0.0 %
Date: 2017-11-07 Branches: 0 30 0.0 %

Line Branch Exec Source
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/* ===---------- emutls.c - Implements __emutls_get_address ---------------===
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 *
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 *                     The LLVM Compiler Infrastructure
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 *
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 * This file is dual licensed under the MIT and the University of Illinois Open
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 * Source Licenses. See LICENSE.TXT for details.
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 *
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 * ===----------------------------------------------------------------------===
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 */
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#include <pthread.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include "int_lib.h"
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#include "int_util.h"
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/* Default is not to use posix_memalign, so systems like Android
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 * can use thread local data without heavier POSIX memory allocators.
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 */
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#ifndef EMUTLS_USE_POSIX_MEMALIGN
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#define EMUTLS_USE_POSIX_MEMALIGN 0
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#endif
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/* For every TLS variable xyz,
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 * there is one __emutls_control variable named __emutls_v.xyz.
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 * If xyz has non-zero initial value, __emutls_v.xyz's "value"
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 * will point to __emutls_t.xyz, which has the initial value.
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 */
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typedef unsigned int gcc_word __attribute__((mode(word)));
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typedef struct __emutls_control {
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    /* Must use gcc_word here, instead of size_t, to match GCC.  When
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       gcc_word is larger than size_t, the upper extra bits are all
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       zeros.  We can use variables of size_t to operate on size and
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       align.  */
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    gcc_word size;  /* size of the object in bytes */
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    gcc_word align;  /* alignment of the object in bytes */
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    union {
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        uintptr_t index;  /* data[index-1] is the object address */
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        void* address;  /* object address, when in single thread env */
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    } object;
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    void* value;  /* null or non-zero initial value for the object */
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} __emutls_control;
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static __inline void *emutls_memalign_alloc(size_t align, size_t size) {
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    void *base;
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#if EMUTLS_USE_POSIX_MEMALIGN
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    if (posix_memalign(&base, align, size) != 0)
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        abort();
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#else
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    #define EXTRA_ALIGN_PTR_BYTES (align - 1 + sizeof(void*))
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    char* object;
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    if ((object = malloc(EXTRA_ALIGN_PTR_BYTES + size)) == NULL)
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        abort();
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    base = (void*)(((uintptr_t)(object + EXTRA_ALIGN_PTR_BYTES))
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                    & ~(uintptr_t)(align - 1));
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    ((void**)base)[-1] = object;
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#endif
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    return base;
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}
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static __inline void emutls_memalign_free(void *base) {
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#if EMUTLS_USE_POSIX_MEMALIGN
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    free(base);
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#else
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    /* The mallocated address is in ((void**)base)[-1] */
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    free(((void**)base)[-1]);
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#endif
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}
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/* Emulated TLS objects are always allocated at run-time. */
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static __inline void *emutls_allocate_object(__emutls_control *control) {
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    /* Use standard C types, check with gcc's emutls.o. */
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    typedef unsigned int gcc_pointer __attribute__((mode(pointer)));
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    COMPILE_TIME_ASSERT(sizeof(uintptr_t) == sizeof(gcc_pointer));
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    COMPILE_TIME_ASSERT(sizeof(uintptr_t) == sizeof(void*));
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    size_t size = control->size;
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    size_t align = control->align;
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    void* base;
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    if (align < sizeof(void*))
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        align = sizeof(void*);
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    /* Make sure that align is power of 2. */
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    if ((align & (align - 1)) != 0)
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        abort();
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    base = emutls_memalign_alloc(align, size);
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    if (control->value)
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        memcpy(base, control->value, size);
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    else
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        memset(base, 0, size);
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    return base;
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}
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static pthread_mutex_t emutls_mutex = PTHREAD_MUTEX_INITIALIZER;
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static size_t emutls_num_object = 0;  /* number of allocated TLS objects */
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typedef struct emutls_address_array {
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    uintptr_t size;  /* number of elements in the 'data' array */
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    void* data[];
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} emutls_address_array;
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static pthread_key_t emutls_pthread_key;
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static void emutls_key_destructor(void* ptr) {
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    emutls_address_array* array = (emutls_address_array*)ptr;
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    uintptr_t i;
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    for (i = 0; i < array->size; ++i) {
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        if (array->data[i])
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            emutls_memalign_free(array->data[i]);
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    }
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    free(ptr);
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}
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static void emutls_init(void) {
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    if (pthread_key_create(&emutls_pthread_key, emutls_key_destructor) != 0)
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        abort();
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}
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/* Returns control->object.index; set index if not allocated yet. */
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static __inline uintptr_t emutls_get_index(__emutls_control *control) {
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    uintptr_t index = __atomic_load_n(&control->object.index, __ATOMIC_ACQUIRE);
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    if (!index) {
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        static pthread_once_t once = PTHREAD_ONCE_INIT;
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        pthread_once(&once, emutls_init);
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        pthread_mutex_lock(&emutls_mutex);
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        index = control->object.index;
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        if (!index) {
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            index = ++emutls_num_object;
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            __atomic_store_n(&control->object.index, index, __ATOMIC_RELEASE);
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        }
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        pthread_mutex_unlock(&emutls_mutex);
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    }
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    return index;
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}
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/* Updates newly allocated thread local emutls_address_array. */
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static __inline void emutls_check_array_set_size(emutls_address_array *array,
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                                                 uintptr_t size) {
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    if (array == NULL)
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        abort();
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    array->size = size;
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    pthread_setspecific(emutls_pthread_key, (void*)array);
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}
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/* Returns the new 'data' array size, number of elements,
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 * which must be no smaller than the given index.
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 */
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static __inline uintptr_t emutls_new_data_array_size(uintptr_t index) {
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   /* Need to allocate emutls_address_array with one extra slot
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    * to store the data array size.
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    * Round up the emutls_address_array size to multiple of 16.
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    */
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    return ((index + 1 + 15) & ~((uintptr_t)15)) - 1;
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}
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/* Returns the thread local emutls_address_array.
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 * Extends its size if necessary to hold address at index.
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 */
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static __inline emutls_address_array *
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emutls_get_address_array(uintptr_t index) {
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    emutls_address_array* array = pthread_getspecific(emutls_pthread_key);
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    if (array == NULL) {
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        uintptr_t new_size = emutls_new_data_array_size(index);
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        array = malloc(new_size * sizeof(void *) + sizeof(emutls_address_array));
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        if (array)
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            memset(array->data, 0, new_size * sizeof(void*));
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        emutls_check_array_set_size(array, new_size);
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    } else if (index > array->size) {
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        uintptr_t orig_size = array->size;
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        uintptr_t new_size = emutls_new_data_array_size(index);
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        array = realloc(array, new_size * sizeof(void *) + sizeof(emutls_address_array));
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        if (array)
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            memset(array->data + orig_size, 0,
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                   (new_size - orig_size) * sizeof(void*));
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        emutls_check_array_set_size(array, new_size);
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    }
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    return array;
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}
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void* __emutls_get_address(__emutls_control* control) {
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    uintptr_t index = emutls_get_index(control);
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    emutls_address_array* array = emutls_get_address_array(index);
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    if (array->data[index - 1] == NULL)
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        array->data[index - 1] = emutls_allocate_object(control);
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    return array->data[index - 1];
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}