alpha: Use saturating arithmetic in memchr

2 files changed, 9 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index f9b94fb58c..b2f41e3da6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2017-02-01  Richard Henderson  <rth@twiddle.net>
+
+	* sysdeps/alpha/memchr.c (__memchr): Use saturating arithmetic
+	adjusting the byte count.
+
 2017-02-01  Andreas Schwab  <schwab@linux-m68k.org>
 
 	* conform/Makefile (linknamespace-libs): Define.
diff --git a/sysdeps/alpha/memchr.c b/sysdeps/alpha/memchr.c
index 82c42c0731..402088dc9e 100644
--- a/sysdeps/alpha/memchr.c
+++ b/sysdeps/alpha/memchr.c
@@ -53,7 +53,10 @@ __memchr (const void *s, int xc, size_t n)
   /* Align the source, and decrement the count by the number
      of bytes searched in the first word.  */
   s_align = (const word *)((word)s & -8);
-  n += ((word)s & 7);
+  {
+    size_t inc = n + ((word)s & 7);
+    n = inc | -(inc < n);
+  }
 
   /* Deal with misalignment in the first word for the comparison.  */
   mask = (1ul << ((word)s & 7)) - 1;