From 9fe7e787adc4f41201c441014fbad318eaae6f80 Mon Sep 17 00:00:00 2001
From: Roland McGrath <roland@hack.frob.com>
Date: Thu, 31 Jul 2014 13:07:19 -0700
Subject: [PATCH] Use __builtin_trap for ABORT_INSTRUCTION.

---
 ChangeLog                     |  6 ++++++
 config.h.in                   |  4 ++++
 configure                     | 38 ++++++++++++++++++++++++++++++++++++++
 configure.ac                  | 17 +++++++++++++++++
 sysdeps/generic/abort-instr.h | 31 ++++++++++++++++++++++++++++++-
 5 files changed, 95 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index d50535c6fb..e359c139d9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2014-07-31  Roland McGrath  <roland@hack.frob.com>
 
+	* config.h.in (HAVE_BUILTIN_TRAP): New #define to 0.
+	* configure.ac (libc_cv_builtin_trap): New test.
+	* configure: Regenerated.
+	* sysdeps/generic/abort-instr.h [HAVE_BUILTIN_TRAP]
+	(ABORT_INSTRUCTION): Define using __builtin_trap.
+
 	* nptl/pthreadP.h (SIGCANCEL, SIGTIMER, SIGSETXID, __xidcmd): Moved ...
 	* sysdeps/unix/sysv/linux/nptl-signals.h: ... to this new file.
 	* sysdeps/nptl/nptl-signals.h: New file.
diff --git a/config.h.in b/config.h.in
index d612a04fe8..7da1a9f6f8 100644
--- a/config.h.in
+++ b/config.h.in
@@ -249,6 +249,10 @@
 /* The pt_chown binary is being built and used by grantpt.  */
 #define HAVE_PT_CHOWN 0
 
+/* Define if the compiler supports __builtin_trap without
+   any external dependencies such as making a function call.  */
+#define HAVE_BUILTIN_TRAP 0
+
 /* ports/sysdeps/mips/configure.in  */
 /* Define if using the IEEE 754-2008 NaN encoding on the MIPS target.  */
 #undef HAVE_MIPS_NAN2008
diff --git a/configure b/configure
index c8d2967f9e..646e0bc9af 100755
--- a/configure
+++ b/configure
@@ -7003,6 +7003,44 @@ if test $libc_cv_ehdr_start = yes; then
 
 fi
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_trap with no external dependencies" >&5
+$as_echo_n "checking for __builtin_trap with no external dependencies... " >&6; }
+if ${libc_cv_builtin_trap+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  libc_cv_builtin_trap=no
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+__builtin_trap ()
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+libc_undefs=`$NM -u conftest.o |
+  LC_ALL=C $AWK '$1 == "U" { print $2 | "sort -u"; next } { exit(1) }' \
+    2>&5` || {
+  as_fn_error $? "confusing output from $NM -u" "$LINENO" 5
+}
+echo >&5 "libc_undefs='$libc_undefs'"
+if test -z "$libc_undefs"; then
+  libc_cv_builtin_trap=yes
+fi
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_builtin_trap" >&5
+$as_echo "$libc_cv_builtin_trap" >&6; }
+if test $libc_cv_builtin_trap = yes; then
+  $as_echo "#define HAVE_BUILTIN_TRAP 1" >>confdefs.h
+
+fi
+
 ### End of automated tests.
 ### Now run sysdeps configure fragments.
 
diff --git a/configure.ac b/configure.ac
index 566ecb276d..e89faa0dfe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1901,6 +1901,23 @@ if test $libc_cv_ehdr_start = yes; then
   AC_DEFINE([HAVE_EHDR_START])
 fi
 
+AC_CACHE_CHECK(for __builtin_trap with no external dependencies,
+	       libc_cv_builtin_trap, [dnl
+libc_cv_builtin_trap=no
+AC_TRY_COMPILE([], [__builtin_trap ()], [
+libc_undefs=`$NM -u conftest.o |
+  LC_ALL=C $AWK '$1 == "U" { print $2 | "sort -u"; next } { exit(1) }' \
+    2>&AS_MESSAGE_LOG_FD` || {
+  AC_MSG_ERROR([confusing output from $NM -u])
+}
+echo >&AS_MESSAGE_LOG_FD "libc_undefs='$libc_undefs'"
+if test -z "$libc_undefs"; then
+  libc_cv_builtin_trap=yes
+fi])])
+if test $libc_cv_builtin_trap = yes; then
+  AC_DEFINE([HAVE_BUILTIN_TRAP])
+fi
+
 ### End of automated tests.
 ### Now run sysdeps configure fragments.
 
diff --git a/sysdeps/generic/abort-instr.h b/sysdeps/generic/abort-instr.h
index 106a330b2b..4ac11d2ea5 100644
--- a/sysdeps/generic/abort-instr.h
+++ b/sysdeps/generic/abort-instr.h
@@ -1,2 +1,31 @@
+/* Magic instruction to crash quickly and reliably.  Generic/stub version.
+   Copyright (C) 2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _ABORT_INSTR_H
+#define _ABORT_INSTR_H  1
+
+/* If the compiler provides the generic way to generate the right
+   instruction, we can use that without any machine-specific knowledge.  */
+#if HAVE_BUILTIN_TRAP
+# define ABORT_INSTRUCTION      __builtin_trap ()
+#else
 /* We cannot give any generic instruction to crash the program.
-   abort() will have to make sure it never returns.  */
+   abort will have to make sure it never returns.  */
+#endif
+
+#endif  /* abort-instr.h */
-- 
2.11.4.GIT