diff options
Diffstat (limited to 'lib/builtins/emutls.c')
| -rw-r--r-- | lib/builtins/emutls.c | 129 |
1 files changed, 60 insertions, 69 deletions
diff --git a/lib/builtins/emutls.c b/lib/builtins/emutls.c index 3cee97f2c..da58feb7b 100644 --- a/lib/builtins/emutls.c +++ b/lib/builtins/emutls.c @@ -1,11 +1,11 @@ -/* ===---------- 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 - * - * ===----------------------------------------------------------------------=== - */ +//===---------- 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> @@ -13,14 +13,14 @@ #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). */ +// 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 @@ -28,7 +28,7 @@ typedef struct emutls_address_array { uintptr_t skip_destructor_rounds; - uintptr_t size; /* number of elements in the 'data' array */ + uintptr_t size; // number of elements in the 'data' array void *data[]; } emutls_address_array; @@ -45,9 +45,8 @@ 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. - */ +// 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 @@ -74,7 +73,7 @@ static __inline void emutls_memalign_free(void *base) { #if EMUTLS_USE_POSIX_MEMALIGN free(base); #else - /* The mallocated address is in ((void**)base)[-1] */ + // The mallocated address is in ((void**)base)[-1] free(((void **)base)[-1]); #endif } @@ -90,13 +89,12 @@ static __inline emutls_address_array *emutls_getspecific() { 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). - */ + // 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 { @@ -120,7 +118,7 @@ static __inline void emutls_lock() { pthread_mutex_lock(&emutls_mutex); } static __inline void emutls_unlock() { pthread_mutex_unlock(&emutls_mutex); } -#else /* _WIN32 */ +#else // _WIN32 #include <assert.h> #include <malloc.h> @@ -218,8 +216,7 @@ static __inline emutls_address_array *emutls_getspecific() { return (emutls_address_array *)value; } -/* Provide atomic load/store functions for emutls_get_index if built with MSVC. - */ +// Provide atomic load/store functions for emutls_get_index if built with MSVC. #if !defined(__ATOMIC_RELEASE) #include <intrin.h> @@ -241,16 +238,15 @@ static __inline void __atomic_store_n(void *ptr, uintptr_t val, unsigned type) { InterlockedExchangePointer((void *volatile *)ptr, (void *)val); } -#endif /* __ATOMIC_RELEASE */ +#endif // __ATOMIC_RELEASE #pragma warning(pop) -#endif /* _WIN32 */ +#endif // _WIN32 -static size_t emutls_num_object = 0; /* number of allocated TLS objects */ +static size_t emutls_num_object = 0; // number of allocated TLS objects -/* Free the allocated TLS data - */ +// Free the allocated TLS data static void emutls_shutdown(emutls_address_array *array) { if (array) { uintptr_t i; @@ -261,28 +257,27 @@ static void emutls_shutdown(emutls_address_array *array) { } } -/* 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. - */ +// 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 */ + // 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 */ + 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 */ + void *value; // null or non-zero initial value for the object } __emutls_control; -/* Emulated TLS objects are always allocated at run-time. */ +// 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. */ + // 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 *)); @@ -291,7 +286,7 @@ static __inline void *emutls_allocate_object(__emutls_control *control) { void *base; if (align < sizeof(void *)) align = sizeof(void *); - /* Make sure that align is power of 2. */ + // Make sure that align is power of 2. if ((align & (align - 1)) != 0) abort(); @@ -303,7 +298,7 @@ static __inline void *emutls_allocate_object(__emutls_control *control) { return base; } -/* Returns control->object.index; set index if not allocated yet. */ +// 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) { @@ -319,7 +314,7 @@ static __inline uintptr_t emutls_get_index(__emutls_control *control) { return index; } -/* Updates newly allocated thread local emutls_address_array. */ +// 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) @@ -328,28 +323,24 @@ static __inline void emutls_check_array_set_size(emutls_address_array *array, emutls_setspecific(array); } -/* Returns the new 'data' array size, number of elements, - * which must be no smaller than the given index. - */ +// 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. - */ + // 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. - */ +// 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. - */ +// 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(); @@ -382,7 +373,7 @@ void *__emutls_get_address(__emutls_control *control) { } #ifdef __BIONIC__ -/* Called by Bionic on dlclose to delete the emutls pthread key. */ +// 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); |