Make xnanosleep's integer overflow test more robust.

* lib/xnanosleep.c (xnanosleep): Declare a temporary to be "volatile",
so that gcc-4.3.0 doesn't optimize away this test for overflow.

Signed-off-by: Jim Meyering <meyering@redhat.com>

diff --git a/ChangeLog b/ChangeLog
index 7401df0..275e2ed 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2007-10-07  Jim Meyering  <meyering@redhat.com>
+
+       Make xnanosleep's integer overflow test more robust.
+       * lib/xnanosleep.c (xnanosleep): Declare a temporary to be "volatile",
+       so that gcc-4.3.0 doesn't optimize away this test for overflow.
+
 2007-10-07  Bruno Haible  <bruno@clisp.org>
 
        * doc/gnulib-intro.texi (Copyright): Update the meaning of the license

diff --git a/lib/xnanosleep.c b/lib/xnanosleep.c
index 6a61ddb..22bd53a 100644 (file)
--- a/lib/xnanosleep.c
+++ b/lib/xnanosleep.c
@@ -72,7 +72,9 @@ xnanosleep (double seconds)
   /* Normalize the interval length.  nanosleep requires this.  */
   if (BILLION <= ts_sleep.tv_nsec)
     {
-      time_t t = ts_sleep.tv_sec + 1;
+      /* Declare "volatile" so that gcc-4.3.0 doesn't optimize away
+        the overflow test.  */
+      volatile time_t t = ts_sleep.tv_sec + 1;
 
       /* Detect integer overflow.  */
       overflow |= (t < ts_sleep.tv_sec);