diff options
Diffstat (limited to 'newlib/libc/stdlib/__atexit.c')
| -rw-r--r-- | newlib/libc/stdlib/__atexit.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/newlib/libc/stdlib/__atexit.c b/newlib/libc/stdlib/__atexit.c index f04f00d8e..d36a1a4e5 100644 --- a/newlib/libc/stdlib/__atexit.c +++ b/newlib/libc/stdlib/__atexit.c @@ -1,5 +1,35 @@ /* * Common routine to implement atexit-like functionality. + * + * This is also the key function to be configured as lite exit, a size-reduced + * implementation of exit that doesn't invoke clean-up functions such as _fini + * or global destructors. + * + * Default (without lite exit) call graph is like: + * _start -> atexit -> __register_exitproc + * _start -> __libc_init_array -> __cxa_atexit -> __register_exitproc + * on_exit -> __register_exitproc + * _start -> exit -> __call_exitprocs + * + * Here an -> means arrow tail invokes arrow head. All invocations here + * are non-weak reference in current newlib/libgloss. + * + * Lite exit makes some of above calls as weak reference, so that size expansive + * functions __register_exitproc and __call_exitprocs may not be linked. These + * calls are: + * _start w-> atexit + * __cxa_atexit w-> __register_exitproc + * exit w-> __call_exitprocs + * + * Lite exit also makes sure that __call_exitprocs will be referenced as non-weak + * whenever __register_exitproc is referenced as non-weak. + * + * Thus with lite exit libs, a program not explicitly calling atexit or on_exit + * will escape from the burden of cleaning up code. A program with atexit or on_exit + * will work consistently to normal libs. + * + * Lite exit is enabled with --enable-lite-exit, and is controlled with macro + * _LITE_EXIT. */ #include <stddef.h> @@ -11,6 +41,12 @@ /* Make this a weak reference to avoid pulling in malloc. */ void * malloc(size_t) _ATTRIBUTE((__weak__)); +#ifdef _LITE_EXIT +/* As __call_exitprocs is weak reference in lite exit, make a + non-weak reference to it here. */ +const void * __atexit_dummy = &__call_exitprocs; +#endif + #ifndef __SINGLE_THREAD__ extern _LOCK_RECURSIVE_T __atexit_lock; #endif |