2013-07-02 Joey Ye <joey.ye@arm.com>

Lite exit support.
        * README: Add information about lite-exit.
        * acconfig.h (_LITE_EXIT): New macro.
        * configure.in (enable-lite-exit): New option.
        (_LITE_EXIT): Define new macro.
        * configure: Regenerated.
        * newlib.hin (_LITE_EXIT): New macro.
        * libc/stdlib/__atexit.c [_LITE_EXIT]: Add dummy explicit
        reference to __call_exitprocs.
        * libc/stdlib/cxa_atexit.c [_LITE_EXIT]: Make __register_exitproc a
        weak reference.
        * libc/stdlib/exit.c (exit)[_LITE_EXIT]: Remove TWS and weakly reference
        __call_exitprocs.

newlib/ChangeLog

@@ -1,3 +1,19 @@
+2013-07-02  Joey Ye  <joey.ye@arm.com>
+
+	Lite exit support.
+	* README: Add information about lite-exit.
+	* acconfig.h (_LITE_EXIT): New macro.
+	* configure.in (enable-lite-exit): New option.
+	(_LITE_EXIT): Define new macro.
+	* configure: Regenerated.
+	* newlib.hin (_LITE_EXIT): New macro.
+	* libc/stdlib/__atexit.c [_LITE_EXIT]: Add dummy explicit 
+	reference to __call_exitprocs.
+	* libc/stdlib/cxa_atexit.c [_LITE_EXIT]: Make __register_exitproc a
+	weak reference.
+	* libc/stdlib/exit.c (exit)[_LITE_EXIT]: Remove TWS and weakly reference
+	__call_exitprocs.
+
 2013-07-02  Jeff Johnston  <jjohnstn@redhat.com>
 
 	* libc/include/sys/reent.h: Fix typo in comment.

newlib/README

@@ -361,6 +361,11 @@ One feature can be enabled by specifying `--enable-FEATURE=yes' or
      Disable newlib from supplying syscalls.
      Enabled by default.
 
+`--enable-lite-exit'
+     Enable lite exit, a size-reduced implementation of exit that doesn't
+     invoke clean-up functions such as _fini or global destructors.
+     Disabled by default.
+
 Running the Testsuite
 =====================
 

newlib/acconfig.h

@@ -67,6 +67,9 @@
 /* Define if unbuffered stream file optimization is supported.  */
 #undef _UNBUF_STREAM_OPT
 
+/* Define if enable lite version of exit.  */
+#undef _LITE_EXIT
+
 @BOTTOM@
 /*
  * Iconv encodings enabled ("to" direction)

newlib/configure

@@ -794,6 +794,7 @@ enable_newlib_fseek_optimization
 enable_newlib_wide_orient
 enable_newlib_nano_malloc
 enable_newlib_unbuf_stream_opt
+enable_lite_exit
 enable_multilib
 enable_target_optspace
 enable_malloc_debugging
@@ -1462,6 +1463,7 @@ Optional Features:
   --disable-newlib-wide-orient    Turn off wide orientation in streamio
   --enable-newlib-nano-malloc    use small-footprint nano-malloc implementation
   --disable-newlib-unbuf-stream-opt    disable unbuffered stream optimization in streamio
+  --enable-lite-exit	enable light weight exit
   --enable-multilib         build many library versions (default)
   --enable-target-optspace  optimize for space
   --enable-malloc-debugging indicate malloc debugging requested
@@ -2425,6 +2427,19 @@ else
   newlib_unbuf_stream_opt=yes
 fi
 
+# Check whether --enable-lite-exit was given.
+if test "${enable_lite_exit+set}" = set; then :
+  enableval=$enable_lite_exit; if test "${lite_exit+set}" != set; then
+  case "${enableval}" in
+    yes) lite_exit=yes ;;
+    no)  lite_exit=no  ;;
+    *)   as_fn_error $? "bad value ${enableval} for lite-exit option" "$LINENO" 5 ;;
+  esac
+ fi
+else
+  lite_exit=no
+fi
+
 
 # Make sure we can run config.sub.
 $SHELL "$ac_aux_dir/config.sub" sun4 >/dev/null 2>&1 ||
@@ -11725,7 +11740,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11698 "configure"
+#line 11743 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11831,7 +11846,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11804 "configure"
+#line 11849 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12341,6 +12356,13 @@ _ACEOF
 
 fi
 
+if test "${lite_exit}" = "yes"; then
+cat >>confdefs.h <<_ACEOF
+#define _LITE_EXIT 1
+_ACEOF
+
+fi
+
 
 if test "x${iconv_encodings}" != "x" \
    || test "x${iconv_to_encodings}" != "x" \

newlib/configure.in

@@ -181,6 +181,19 @@ AC_ARG_ENABLE(newlib-unbuf-stream-opt,
   esac
  fi], [newlib_unbuf_stream_opt=yes])dnl
 
+dnl Support --enable-lite-exit
+dnl Lite exit is a size-reduced implementation of exit that doesn't invoke
+dnl clean-up functions such as _fini or global destructors.
+AC_ARG_ENABLE(lite-exit,
+[  --enable-lite-exit	enable light weight exit],
+[if test "${lite_exit+set}" != set; then
+  case "${enableval}" in
+    yes) lite_exit=yes ;;
+    no)  lite_exit=no  ;;
+    *)   AC_MSG_ERROR(bad value ${enableval} for lite-exit option) ;;
+  esac
+ fi], [lite_exit=no])dnl
+
 NEWLIB_CONFIGURE(.)
 
 dnl We have to enable libtool after NEWLIB_CONFIGURE because if we try and
@@ -390,6 +403,10 @@ if test "${newlib_unbuf_stream_opt}" = "yes"; then
 AC_DEFINE_UNQUOTED(_UNBUF_STREAM_OPT)
 fi
 
+if test "${lite_exit}" = "yes"; then
+AC_DEFINE_UNQUOTED(_LITE_EXIT)
+fi
+
 dnl
 dnl Parse --enable-newlib-iconv-encodings option argument
 dnl

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

newlib/libc/stdlib/cxa_atexit.c

@@ -19,5 +19,14 @@ _DEFUN (__cxa_atexit,
 	void *arg _AND
 	void *d)
 {
-  return __register_exitproc (__et_cxa, (void (*)(void)) fn, arg, d);
+#ifdef _LITE_EXIT
+  /* Refer to comments in __atexit.c for more details of lite exit.  */
+  int __register_exitproc _PARAMS ((int, void (*fn) (void), _PTR, _PTR))
+    __attribute__ ((weak));
+
+  if (!__register_exitproc)
+    return 0;
+  else
+#endif
+    return __register_exitproc (__et_cxa, (void (*)(void)) fn, arg, d);
 }

newlib/libc/stdlib/exit.c

@@ -54,11 +54,16 @@ Supporting OS subroutines required: <<_exit>>.
  * Exit, flushing stdio buffers if necessary.
  */
 
-void 
+void
 _DEFUN (exit, (code),
 	int code)
 {
-  __call_exitprocs (code, NULL);
+#ifdef _LITE_EXIT
+  /* Refer to comments in __atexit.c for more details of lite exit.  */
+  void __call_exitprocs _PARAMS ((int, _PTR)) __attribute__((weak));
+  if (__call_exitprocs)
+#endif
+    __call_exitprocs (code, NULL);
 
   if (_GLOBAL_REENT->__cleanup)
     (*_GLOBAL_REENT->__cleanup) (_GLOBAL_REENT);

newlib/newlib.hin

@@ -70,6 +70,9 @@
 /* Define if unbuffered stream file optimization is supported.  */
 #undef _UNBUF_STREAM_OPT
 
+/* Define if lite version of exit supported.  */
+#undef _LITE_EXIT
+
 /*
  * Iconv encodings enabled ("to" direction)
  */