PR 47571 Fix HPUX bootstrap regression, cleanup

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@169852 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 71 insertions, 2 deletions

diff --git a/libgfortran/intrinsics/system_clock.c b/libgfortran/intrinsics/system_clock.c
index 37155628d53..3a44dd9666b 100644
--- a/libgfortran/intrinsics/system_clock.c
+++ b/libgfortran/intrinsics/system_clock.c
@@ -29,6 +29,75 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 
 #include "time_1.h"
 
+#ifdef HAVE_CLOCK_GETTIME
+/* POSIX states that CLOCK_REALTIME must be present if clock_gettime
+   is available, others are optional.  */
+#ifdef CLOCK_MONOTONIC
+#define GF_CLOCK_MONOTONIC CLOCK_MONOTONIC
+#else
+#define GF_CLOCK_MONOTONIC CLOCK_REALTIME
+#endif
+
+/* Weakref trickery for clock_gettime().  On Glibc, clock_gettime()
+   requires us to link in librt, which also pulls in libpthread.  In
+   order to avoid this by default, only call clock_gettime() through a
+   weak reference. 
+
+   Some targets don't support weak undefined references; on these
+   GTHREAD_USE_WEAK is 0. So we need to define it to 1 on other
+   targets.  */
+#ifndef GTHREAD_USE_WEAK
+#define GTHREAD_USE_WEAK 1
+#endif
+
+#if SUPPORTS_WEAK && GTHREAD_USE_WEAK
+static int weak_gettime (clockid_t, struct timespec *) 
+  __attribute__((__weakref__("clock_gettime")));
+#else
+static inline int weak_gettime (clockid_t clk_id, struct timespec *res)
+{
+  return clock_gettime (clk_id, res);
+}
+#endif
+#endif
+
+
+/* High resolution monotonic clock, falling back to the realtime clock
+   if the target does not support such a clock.
+
+   Arguments:
+   secs     - OUTPUT, seconds
+   nanosecs - OUTPUT, nanoseconds
+
+   If the target supports a monotonic clock, the OUTPUT arguments
+   represent a monotonically incrementing clock starting from some
+   unspecified time in the past.
+
+   If a monotonic clock is not available, falls back to the realtime
+   clock which is not monotonic.
+
+   Return value: 0 for success, -1 for error. In case of error, errno
+   is set.
+*/
+static inline int
+gf_gettime_mono (time_t * secs, long * nanosecs)
+{
+  int err;
+#ifdef HAVE_CLOCK_GETTIME
+  if (weak_gettime)
+    {
+      struct timespec ts;
+      err = weak_gettime (GF_CLOCK_MONOTONIC, &ts);
+      *secs = ts.tv_sec;
+      *nanosecs = ts.tv_nsec;
+      return err;
+    }
+#endif
+  err = gf_gettime (secs, nanosecs);
+  *nanosecs *= 1000;
+  return err;
+}
+
 extern void system_clock_4 (GFC_INTEGER_4 *, GFC_INTEGER_4 *, GFC_INTEGER_4 *);
 export_proto(system_clock_4);
 
@@ -56,7 +125,7 @@ system_clock_4(GFC_INTEGER_4 *count, GFC_INTEGER_4 *count_rate,
   if (sizeof (secs) < sizeof (GFC_INTEGER_4))
     internal_error (NULL, "secs too small");
 
-  if (gf_gettime (GF_CLOCK_MONOTONIC, &secs, &nanosecs) == 0)
+  if (gf_gettime_mono (&secs, &nanosecs) == 0)
     {
       GFC_UINTEGER_4 ucnt = (GFC_UINTEGER_4) secs * TCK;
       ucnt += (nanosecs + 500000000 / TCK) / (1000000000 / TCK);
@@ -103,7 +172,7 @@ system_clock_8 (GFC_INTEGER_8 *count, GFC_INTEGER_8 *count_rate,
   if (sizeof (secs) < sizeof (GFC_INTEGER_4))
     internal_error (NULL, "secs too small");
 
-  if (gf_gettime (GF_CLOCK_MONOTONIC, &secs, &nanosecs) == 0)
+  if (gf_gettime_mono (&secs, &nanosecs) == 0)
     {
       GFC_UINTEGER_8 ucnt = (GFC_UINTEGER_8) secs * TCK;
       ucnt += (nanosecs + 500000000 / TCK) / (1000000000 / TCK);