On Mon, Jan 05, 2015 at 08:47:35PM -0800, Paul Eggert wrote:
> H.J. Lu wrote:
> >assert (CLOCKS_PER_SEC == 1000000l);
>
> This fails only at runtime if the value is wrong, which is not as good as
> checking it at compile-time. Something like this, perhaps:
>
> #if __STDC_VERSION__ < 201112L
> # define _Static_assert(e, s) extern int (*static_assert_checker (void)) \
> [sizeof (struct { unsigned int error_if_negative: (e) ? 1 : -1; })]
> #endif
> #define verify(e) _Static_assert (e, "verify (" #e ")")
>
> and then use 'verify' instead of 'assert'.
>
> Also, there's no need for the trailing 'l' here.
This is what I am checking in. _Static_assert is added to GCC 4.6 which
is the minimum GCC version required for glibc build. Tested with GCC
4.6 and 4.8.
H.J.
---
[BZ #17797]
* bits/time.h (CLOCKS_PER_SEC): Changed to ((clock_t) 1000000).
* sysdeps/unix/sysv/linux/bits/time.h (CLOCKS_PER_SEC): Likewise.
* sysdeps/unix/sysv/linux/clock.c (clock): _Static_assert
CLOCKS_PER_SEC == 1000000.
* time/clocktest.c (main): Replace %ld with %jd and cast to
intmax_t.
---
ChangeLog | 10 ++++++++++
NEWS | 2 +-
bits/time.h | 8 ++++----
sysdeps/unix/sysv/linux/bits/time.h | 8 ++++----
sysdeps/unix/sysv/linux/clock.c | 7 +++----
time/clocktest.c | 4 ++--
6 files changed, 24 insertions(+), 15 deletions(-)
@@ -1,3 +1,13 @@
+2015-01-06 H.J. Lu <hongjiu.lu@intel.com>
+
+ [BZ #17797]
+ * bits/time.h (CLOCKS_PER_SEC): Changed to ((clock_t) 1000000).
+ * sysdeps/unix/sysv/linux/bits/time.h (CLOCKS_PER_SEC): Likewise.
+ * sysdeps/unix/sysv/linux/clock.c (clock): _Static_assert
+ CLOCKS_PER_SEC == 1000000.
+ * time/clocktest.c (main): Replace %ld with %jd and cast to
+ intmax_t.
+
2015-01-05 Roland McGrath <roland@hack.frob.com>
* sysdeps/generic/unwind-resume.h: New file.
@@ -16,7 +16,7 @@ Version 2.21
17583, 17584, 17585, 17589, 17594, 17601, 17608, 17616, 17625, 17630,
17633, 17634, 17635, 17647, 17653, 17657, 17664, 17665, 17668, 17682,
17717, 17719, 17722, 17723, 17724, 17725, 17732, 17733, 17744, 17745,
- 17746, 17747, 17775, 17777, 17780, 17781, 17782, 17793, 17796
+ 17746, 17747, 17775, 17777, 17780, 17781, 17782, 17793, 17796, 17797
* i386 memcpy functions optimized with SSE2 unaligned load/store.
@@ -24,13 +24,13 @@
# ifndef _BITS_TIME_H
# define _BITS_TIME_H 1
-/* ISO/IEC 9899:1990 7.12.1: <time.h>
- The macro `CLOCKS_PER_SEC' is the number per second of the value
- returned by the `clock' function. */
+/* ISO/IEC 9899:1999 7.23.1: Components of time
+ The macro `CLOCKS_PER_SEC' is an expression with type `clock_t' that is
+ the number per second of the value returned by the `clock' function. */
/* CAE XSH, Issue 4, Version 2: <time.h>
The value of CLOCKS_PER_SEC is required to be 1 million on all
XSI-conformant systems. */
-# define CLOCKS_PER_SEC 1000000l
+# define CLOCKS_PER_SEC ((clock_t) 1000000)
# if !defined __STRICT_ANSI__ && !defined __USE_XOPEN2K
/* Even though CLOCKS_PER_SEC has such a strange value CLK_TCK
@@ -39,13 +39,13 @@ struct timeval
# ifndef _BITS_TIME_H
# define _BITS_TIME_H 1
-/* ISO/IEC 9899:1990 7.12.1: <time.h>
- The macro `CLOCKS_PER_SEC' is the number per second of the value
- returned by the `clock' function. */
+/* ISO/IEC 9899:1999 7.23.1: Components of time
+ The macro `CLOCKS_PER_SEC' is an expression with type `clock_t' that is
+ the number per second of the value returned by the `clock' function. */
/* CAE XSH, Issue 4, Version 2: <time.h>
The value of CLOCKS_PER_SEC is required to be 1 million on all
XSI-conformant systems. */
-# define CLOCKS_PER_SEC 1000000l
+# define CLOCKS_PER_SEC ((clock_t) 1000000)
# if (!defined __STRICT_ANSI__ || defined __USE_POSIX) \
&& !defined __USE_XOPEN2K
@@ -20,15 +20,14 @@
#include <time.h>
#include <unistd.h>
-#if CLOCKS_PER_SEC != 1000000l
-# error "CLOCKS_PER_SEC should be 1000000"
-#endif
-
clock_t
clock (void)
{
struct timespec ts;
+ _Static_assert (CLOCKS_PER_SEC == 1000000,
+ "CLOCKS_PER_SEC should be 1000000");
+
/* clock_gettime shouldn't fail here since CLOCK_PROCESS_CPUTIME_ID is
supported since 2.6.12. Check the return value anyway in case the kernel
barfs on us for some reason. */
@@ -30,7 +30,7 @@ main (int argc, char ** argv)
printf ("%jd clock ticks per second (start=%jd,stop=%jd)\n",
(intmax_t) (stop - start), (intmax_t) start, (intmax_t) stop);
- printf ("CLOCKS_PER_SEC=%ld, sysconf(_SC_CLK_TCK)=%ld\n",
- CLOCKS_PER_SEC, sysconf(_SC_CLK_TCK));
+ printf ("CLOCKS_PER_SEC=%jd, sysconf(_SC_CLK_TCK)=%ld\n",
+ (intmax_t) CLOCKS_PER_SEC, sysconf(_SC_CLK_TCK));
return 0;
}