[git commit] ldso: mark _dl_exit as noreturn

Bernhard Reutner-Fischer rep.dot.nop at gmail.com
Wed Mar 25 23:02:58 UTC 2015


commit: http://git.uclibc.org/uClibc/commit/?id=2c8a7766681b704e710f51c0817534e3f9a952d1
branch: http://git.uclibc.org/uClibc/commit/?id=refs/heads/master

Otherwise gcc might not understand that oom() ended control-flow and
might emit an (untaken) reference to abort() in _dl_update_slotinfo()
on e.g. SH4 which breaks linking ld-uClibc.so.
Arguably -ffreestanding should prevent GCC from emitting this
'.global abort' but alas, it does not, which is another bug..

Also mark the function cold to further lower the incoming frequency and
branch probability.

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop at gmail.com>
---
 ldso/include/dl-syscall.h |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/ldso/include/dl-syscall.h b/ldso/include/dl-syscall.h
index 675b93a..e556f7b 100644
--- a/ldso/include/dl-syscall.h
+++ b/ldso/include/dl-syscall.h
@@ -52,7 +52,15 @@ extern int _dl_errno;
    dynamic linking at all, so we cannot return any error codes.
    We just punt if there is an error. */
 #define __NR__dl_exit __NR_exit
-static __always_inline _syscall1(void, _dl_exit, int, status)
+static __always_inline attribute_noreturn __cold void _dl_exit(int status)
+{
+	INLINE_SYSCALL(_dl_exit, 1, status);
+#if defined __GNUC__
+	__builtin_unreachable(); /* shut up warning: 'noreturn' function does return*/
+#else
+	while (1);
+#endif
+}
 
 #define __NR__dl_close __NR_close
 static __always_inline _syscall1(int, _dl_close, int, fd)


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