[PATCH 7/7] Use global atexit data for all configurations

For the exit processing only members of _GLOBAL_REENT were used by default.  If
the _REENT_GLOBAL_ATEXIT option was enabled, then the data structures were
provided to dedicated global objects.  Make this option the default.  Remove
the option.  Provide the struct _reent _atexit and atexit members only if
backward binary compatibility is requested (_NEWLIB_BACKWARD_BINARY_COMPAT).
---
 newlib/README                      |  6 ------
 newlib/configure                   |  7 -------
 newlib/configure.ac                |  8 ++------
 newlib/libc/include/sys/config.h   |  1 -
 newlib/libc/include/sys/reent.h    | 30 ++++++++++--------------------
 newlib/libc/reent/reent.c          | 19 -------------------
 newlib/libc/stdlib/__atexit.c      | 15 +++++----------
 newlib/libc/stdlib/__call_atexit.c |  8 +++-----
 newlib/newlib.hin                  |  3 ---
 9 files changed, 20 insertions(+), 77 deletions(-)

diff --git a/newlib/README b/newlib/README
index 54921893f..8cf37c5ef 100644
--- a/newlib/README
+++ b/newlib/README
@@ -294,12 +294,6 @@ One feature can be enabled by specifying `--enable-FEATURE=yes' or
      Disable dynamic allocation of atexit entries.
      Most hosts and targets have it enabled in configure.host.
 
-`--enable-newlib-global-atexit'
-     Enable atexit data structure as global variable.  By doing so it is
-     move out of _reent structure, and can be garbage collected if atexit
-     is not referenced.
-     Disabled by default.
-
 `--enable-newlib-global-stdio-streams'
      Enable to move the stdio stream FILE objects out of struct _reent and make
      them global.  The stdio stream pointers of struct _reent are initialized
diff --git a/newlib/configure b/newlib/configure
index 6ea3f5631..02e243de7 100755
--- a/newlib/configure
+++ b/newlib/configure
@@ -2373,7 +2373,6 @@ if test "${enable_newlib_global_atexit+set}" = set; then :
   enableval=$enable_newlib_global_atexit; if test "${newlib_global_atexit+set}" != set; then
   case "${enableval}" in
     yes) newlib_global_atexit=yes ;;
-    no)  newlib_global_atexit=no  ;;
     *)   as_fn_error $? "bad value ${enableval} for newlib-global-atexit option" "$LINENO" 5 ;;
   esac
  fi
@@ -6478,12 +6477,6 @@ $as_echo "#define _ATEXIT_DYNAMIC_ALLOC 1" >>confdefs.h
 
 fi
 
-if test "${newlib_global_atexit}" = "yes"; then
-
-$as_echo "#define _REENT_GLOBAL_ATEXIT 1" >>confdefs.h
-
-fi
-
 if test "${newlib_fvwrite_in_streamio}" = "yes"; then
 
 $as_echo "#define _FVWRITE_IN_STREAMIO 1" >>confdefs.h
diff --git a/newlib/configure.ac b/newlib/configure.ac
index 556580967..196daeb0a 100644
--- a/newlib/configure.ac
+++ b/newlib/configure.ac
@@ -142,13 +142,13 @@ AC_ARG_ENABLE(newlib-atexit-dynamic-alloc,
 
 dnl Support --enable-newlib-global-atexit
 dnl Enable atexit data structure as global variables to save memory usage in
-dnl _reent.
+dnl _reent.  This is no longer optional.  It is enabled in all Newlib
+dnl configurations.
 AC_ARG_ENABLE(newlib-global-atexit,
 [  --enable-newlib-global-atexit	enable atexit data structure as global],
 [if test "${newlib_global_atexit+set}" != set; then
   case "${enableval}" in
     yes) newlib_global_atexit=yes ;;
-    no)  newlib_global_atexit=no  ;;
     *)   AC_MSG_ERROR(bad value ${enableval} for newlib-global-atexit option) ;;
   esac
  fi], [newlib_global_atexit=no])dnl
@@ -466,10 +466,6 @@ if test "${newlib_atexit_dynamic_alloc}" = "yes"; then
   AC_DEFINE(_ATEXIT_DYNAMIC_ALLOC, 1, [If atexit() may dynamically allocate space for cleanup functions.])
 fi
 
-if test "${newlib_global_atexit}" = "yes"; then
-  AC_DEFINE(_REENT_GLOBAL_ATEXIT, 1, [Define if declare atexit data as global.])
-fi
-
 if test "${newlib_fvwrite_in_streamio}" = "yes"; then
   AC_DEFINE(_FVWRITE_IN_STREAMIO, 1, [Define if ivo supported in streamio.])
 fi
diff --git a/newlib/libc/include/sys/config.h b/newlib/libc/include/sys/config.h
index fbc1e0fe1..7bbba2497 100644
--- a/newlib/libc/include/sys/config.h
+++ b/newlib/libc/include/sys/config.h
@@ -242,7 +242,6 @@
 #define __FILENAME_MAX__ 255
 #define _READ_WRITE_RETURN_TYPE _ssize_t
 #define __DYNAMIC_REENT__
-#define _REENT_GLOBAL_ATEXIT
 #define _REENT_GLOBAL_STDIO_STREAMS
 #endif
 
diff --git a/newlib/libc/include/sys/reent.h b/newlib/libc/include/sys/reent.h
index c21f11de2..d1d84ffe5 100644
--- a/newlib/libc/include/sys/reent.h
+++ b/newlib/libc/include/sys/reent.h
@@ -105,13 +105,6 @@ struct _atexit {
 # define _ATEXIT_INIT {_NULL, 0, {_NULL}, {{_NULL}, {_NULL}, 0, 0}}
 #endif
 
-#ifdef _REENT_GLOBAL_ATEXIT
-# define _REENT_INIT_ATEXIT
-#else
-# define _REENT_INIT_ATEXIT \
-  _NULL, _ATEXIT_INIT,
-#endif
-
 /*
  * Stdio buffers.
  *
@@ -343,10 +336,12 @@ struct _rand48 {
 #define _REENT_SIGNAL_SIZE 24
 
 #ifdef _NEWLIB_BACKWARD_BINARY_COMPAT
+#define _REENT_INIT_UNUSED_ATEXIT _NULL, _ATEXIT_INIT,
 #define _REENT_INIT_UNUSED_LOCALE_INFO 0,
 #define _REENT_INIT_UNUSED_RAND 0,
 #define _REENT_INIT_UNUSED_SDIDINIT 0,
 #else
+#define _REENT_INIT_UNUSED_ATEXIT /* Nothing to initialize */
 #define _REENT_INIT_UNUSED_LOCALE_INFO /* Nothing to initialize */
 #define _REENT_INIT_UNUSED_RAND /* Nothing to initialize */
 #define _REENT_INIT_UNUSED_SDIDINIT /* Nothing to initialize */
@@ -431,11 +426,11 @@ struct _reent
   /* signal info */
   void (**(_sig_func))(int);
 
-# ifndef _REENT_GLOBAL_ATEXIT
+#ifdef _NEWLIB_BACKWARD_BINARY_COMPAT
   /* atexit stuff */
   struct _atexit *_atexit;
   struct _atexit _atexit0;
-# endif
+#endif
 
   struct _glue __sglue;			/* root of glue chain */
   __FILE *__sf;			        /* file descriptors */
@@ -464,7 +459,7 @@ struct _reent
     _NULL, \
     _NULL, \
     _NULL, \
-    _REENT_INIT_ATEXIT \
+    _REENT_INIT_UNUSED_ATEXIT \
     {_NULL, 0, _NULL}, \
     _NULL, \
     _NULL, \
@@ -502,7 +497,7 @@ extern const struct __sFILE_fake __sf_fake_stderr;
     _NULL, \
     _NULL, \
     _NULL, \
-    _REENT_INIT_ATEXIT \
+    _REENT_INIT_UNUSED_ATEXIT \
     {_NULL, 0, _NULL}, \
     _NULL, \
     _NULL, \
@@ -704,11 +699,11 @@ struct _reent
 #endif
     } _new;
 
-# ifndef _REENT_GLOBAL_ATEXIT
+#ifdef _NEWLIB_BACKWARD_BINARY_COMPAT
   /* atexit stuff */
   struct _atexit *_atexit;	/* points to head of LIFO stack */
   struct _atexit _atexit0;	/* one guaranteed table, required by ANSI */
-# endif
+#endif
 
   /* signal info */
   void (**_sig_func)(int);
@@ -777,7 +772,7 @@ struct _reent
         {0, {0}} \
       } \
     }, \
-    _REENT_INIT_ATEXIT \
+    _REENT_INIT_UNUSED_ATEXIT \
     _NULL \
     _REENT_INIT_SGLUE(&(var)) \
   }
@@ -879,12 +874,7 @@ extern int _fwalk_sglue (struct _reent *, int (*)(struct _reent *, __FILE *),
 
 #define _GLOBAL_REENT (&_impure_data)
 
-#ifdef _REENT_GLOBAL_ATEXIT
-extern struct _atexit *_global_atexit; /* points to head of LIFO stack */
-# define _GLOBAL_ATEXIT _global_atexit
-#else
-# define _GLOBAL_ATEXIT (_GLOBAL_REENT->_atexit)
-#endif
+extern struct _atexit *__atexit; /* points to head of LIFO stack */
 
 #ifdef __cplusplus
 }
diff --git a/newlib/libc/reent/reent.c b/newlib/libc/reent/reent.c
index 70f1c5f45..04942ce4d 100644
--- a/newlib/libc/reent/reent.c
+++ b/newlib/libc/reent/reent.c
@@ -93,25 +93,6 @@ _reclaim_reent (struct _reent *ptr)
 	_free_r (ptr, ptr->_misc);
 #endif
 
-#ifndef _REENT_GLOBAL_ATEXIT
-      /* atexit stuff */
-# ifdef _REENT_SMALL
-      if (ptr->_atexit && ptr->_atexit->_on_exit_args_ptr)
-	_free_r (ptr, ptr->_atexit->_on_exit_args_ptr);
-# else
-      if ((ptr->_atexit) && (ptr->_atexit != &ptr->_atexit0))
-	{
-	  struct _atexit *p, *q;
-	  for (p = ptr->_atexit; p != &ptr->_atexit0;)
-	    {
-	      q = p;
-	      p = p->_next;
-	      _free_r (ptr, q);
-	    }
-	}
-# endif
-#endif
-
       if (ptr->_cvtbuf)
 	_free_r (ptr, ptr->_cvtbuf);
     /* We should free _sig_func to avoid a memory leak, but how to
diff --git a/newlib/libc/stdlib/__atexit.c b/newlib/libc/stdlib/__atexit.c
index 97ce053bf..3f7bf8c2b 100644
--- a/newlib/libc/stdlib/__atexit.c
+++ b/newlib/libc/stdlib/__atexit.c
@@ -53,12 +53,7 @@ const void * __atexit_dummy = &__call_exitprocs;
 extern _LOCK_RECURSIVE_T __atexit_recursive_mutex;
 #endif
 
-#ifdef _REENT_GLOBAL_ATEXIT
-static struct _atexit _global_atexit0 = _ATEXIT_INIT;
-# define _GLOBAL_ATEXIT0 (&_global_atexit0)
-#else
-# define _GLOBAL_ATEXIT0 (&_GLOBAL_REENT->_atexit0)
-#endif
+static struct _atexit atexit0 = _ATEXIT_INIT;
 
 /*
  * Register a function to be performed at exit or on shared library unload.
@@ -77,10 +72,10 @@ __register_exitproc (int type,
   __lock_acquire_recursive(__atexit_recursive_mutex);
 #endif
 
-  p = _GLOBAL_ATEXIT;
+  p = __atexit;
   if (p == NULL)
     {
-      _GLOBAL_ATEXIT = p = _GLOBAL_ATEXIT0;
+      __atexit = p = &atexit0;
 #ifdef _REENT_SMALL
       extern struct _on_exit_args * const __on_exit_args _ATTRIBUTE ((weak));
       if (&__on_exit_args != NULL)
@@ -104,8 +99,8 @@ __register_exitproc (int type,
 	  return -1;
 	}
       p->_ind = 0;
-      p->_next = _GLOBAL_ATEXIT;
-      _GLOBAL_ATEXIT = p;
+      p->_next = __atexit;
+      __atexit = p;
 #ifndef _REENT_SMALL
       p->_on_exit_args._fntypes = 0;
       p->_on_exit_args._is_cxa = 0;
diff --git a/newlib/libc/stdlib/__call_atexit.c b/newlib/libc/stdlib/__call_atexit.c
index c29a03c8e..710440389 100644
--- a/newlib/libc/stdlib/__call_atexit.c
+++ b/newlib/libc/stdlib/__call_atexit.c
@@ -17,9 +17,7 @@ void free(void *) _ATTRIBUTE((__weak__));
 __LOCK_INIT_RECURSIVE(, __atexit_recursive_mutex);
 #endif
 
-#ifdef _REENT_GLOBAL_ATEXIT
-struct _atexit *_global_atexit = _NULL;
-#endif
+struct _atexit *__atexit = _NULL;
 
 #ifdef _WANT_REGISTER_FINI
 
@@ -83,8 +81,8 @@ __call_exitprocs (int code, void *d)
 
  restart:
 
-  p = _GLOBAL_ATEXIT;
-  lastp = &_GLOBAL_ATEXIT;
+  p = __atexit;
+  lastp = &__atexit;
   while (p)
     {
 #ifdef _REENT_SMALL
diff --git a/newlib/newlib.hin b/newlib/newlib.hin
index cf3086c32..f59fc57aa 100644
--- a/newlib/newlib.hin
+++ b/newlib/newlib.hin
@@ -378,9 +378,6 @@
 /* Verify _REENT_CHECK macros allocate memory successfully. */
 #undef _REENT_CHECK_VERIFY
 
-/* Define if declare atexit data as global. */
-#undef _REENT_GLOBAL_ATEXIT
-
 /* Define if using retargetable functions for default lock routines. */
 #undef _RETARGETABLE_LOCKING
 
-- 
2.35.3