Reorganisation of the source tree

Most of the other users of the fptools build system have migrated to
Cabal, and with the move to darcs we can now flatten the source tree
without losing history, so here goes.

The main change is that the ghc/ subdir is gone, and most of what it
contained is now at the top level.  The build system now makes no
pretense at being multi-project, it is just the GHC build system.

No doubt this will break many things, and there will be a period of
instability while we fix the dependencies.  A straightforward build
should work, but I haven't yet fixed binary/source distributions.
Changes to the Building Guide will follow, too.

1 files changed, 226 insertions, 0 deletions

diff --git a/rts/posix/Itimer.c b/rts/posix/Itimer.c
new file mode 100644
index 0000000000..83ed84d6ef
--- /dev/null
+++ b/rts/posix/Itimer.c
@@ -0,0 +1,226 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team, 1995-1999
+ *
+ * Interval timer for profiling and pre-emptive scheduling.
+ *
+ * ---------------------------------------------------------------------------*/
+
+/*
+ * The interval timer is used for profiling and for context switching in the
+ * threaded build.  Though POSIX 1003.1b includes a standard interface for
+ * such things, no one really seems to be implementing them yet.  Even 
+ * Solaris 2.3 only seems to provide support for @CLOCK_REAL@, whereas we're
+ * keen on getting access to @CLOCK_VIRTUAL@.
+ * 
+ * Hence, we use the old-fashioned @setitimer@ that just about everyone seems
+ * to support.  So much for standards.
+ */
+#include "Rts.h"
+#include "RtsFlags.h"
+#include "Timer.h"
+#include "Ticker.h"
+#include "posix/Itimer.h"
+#include "Proftimer.h"
+#include "Schedule.h"
+#include "posix/Select.h"
+
+/* As recommended in the autoconf manual */
+# ifdef TIME_WITH_SYS_TIME
+#  include <sys/time.h>
+#  include <time.h>
+# else
+#  ifdef HAVE_SYS_TIME_H
+#   include <sys/time.h>
+#  else
+#   include <time.h>
+#  endif
+# endif
+
+#ifdef HAVE_SIGNAL_H
+# include <signal.h>
+#endif
+
+/* Major bogosity:
+ * 
+ * In the threaded RTS, we can't set the virtual timer because the
+ * thread which has the virtual timer might be sitting waiting for a
+ * capability, and the virtual timer only ticks in CPU time.
+ *
+ * So, possible solutions:
+ *
+ * (1) tick in realtime.  Not very good, because this ticker is used for
+ *     profiling, and this will give us unreliable time profiling
+ *     results.  Furthermore, this requires picking a single OS thread
+ *     to be the timekeeper, which is a bad idea because the thread in
+ *     question might just be making a temporary call into Haskell land.
+ *
+ * (2) save/restore the virtual timer around excursions into STG land.
+ *     Sounds great, but I tried it and the resolution of the virtual timer
+ *     isn't good enough (on Linux) - most of our excursions fall
+ *     within the timer's resolution and we never make any progress.
+ *   
+ * (3) have a virtual timer in every OS thread.  Might be reasonable,
+ *     because most of the time there is only ever one of these
+ *     threads running, so it approximates a single virtual timer.
+ *     But still quite bogus (and I got crashes when I tried this).
+ *
+ * For now, we're using (1), but this needs a better solution. --SDM
+ */
+#ifdef THREADED_RTS
+#define ITIMER_FLAVOUR  ITIMER_REAL
+#define ITIMER_SIGNAL   SIGALRM
+#else
+#define ITIMER_FLAVOUR  ITIMER_VIRTUAL
+#define ITIMER_SIGNAL   SIGVTALRM
+#endif
+
+static
+int
+install_vtalrm_handler(TickProc handle_tick)
+{
+    struct sigaction action;
+
+    action.sa_handler = handle_tick;
+
+    sigemptyset(&action.sa_mask);
+
+#ifdef SA_RESTART
+    // specify SA_RESTART.  One consequence if we don't do this is
+    // that readline gets confused by the -threaded RTS.  It seems
+    // that if a SIGALRM handler is installed without SA_RESTART,
+    // readline installs its own SIGALRM signal handler (see
+    // readline's signals.c), and this somehow causes readline to go
+    // wrong when the input exceeds a single line (try it).
+    action.sa_flags = SA_RESTART;
+#else
+    action.sa_flags = 0;
+#endif
+
+    return sigaction(ITIMER_SIGNAL, &action, NULL);
+}
+
+int
+startTicker(nat ms, TickProc handle_tick)
+{
+# ifndef HAVE_SETITIMER
+  /*    debugBelch("No virtual timer on this system\n"); */
+    return -1;
+# else
+    struct itimerval it;
+
+    install_vtalrm_handler(handle_tick);
+
+#if !defined(THREADED_RTS)
+    timestamp = getourtimeofday();
+#endif
+
+    it.it_value.tv_sec = ms / 1000;
+    it.it_value.tv_usec = 1000 * (ms - (1000 * it.it_value.tv_sec));
+    it.it_interval = it.it_value;
+    return (setitimer(ITIMER_FLAVOUR, &it, NULL));
+# endif
+}
+
+int
+stopTicker()
+{
+# ifndef HAVE_SETITIMER
+  /*    debugBelch("No virtual timer on this system\n"); */
+    return -1;
+# else
+    struct itimerval it;
+  
+    it.it_value.tv_sec = 0;
+    it.it_value.tv_usec = 0;
+    it.it_interval = it.it_value;
+    return (setitimer(ITIMER_FLAVOUR, &it, NULL));
+# endif
+}
+
+# if 0
+/* This is a potential POSIX version */
+int
+startTicker(nat ms)
+{
+    struct sigevent se;
+    struct itimerspec it;
+    timer_t tid;
+
+#if !defined(THREADED_RTS)
+    timestamp = getourtimeofday();
+#endif
+
+    se.sigev_notify = SIGEV_SIGNAL;
+    se.sigev_signo = ITIMER_SIGNAL;
+    se.sigev_value.sival_int = ITIMER_SIGNAL;
+    if (timer_create(CLOCK_VIRTUAL, &se, &tid)) {
+	barf("can't create virtual timer");
+    }
+    it.it_value.tv_sec = ms / 1000;
+    it.it_value.tv_nsec = 1000000 * (ms - 1000 * it.it_value.tv_sec);
+    it.it_interval = it.it_value;
+    return timer_settime(tid, TIMER_RELTIME, &it, NULL);
+}
+
+int
+stopTicker()
+{
+    struct sigevent se;
+    struct itimerspec it;
+    timer_t tid;
+
+#if !defined(THREADED_RTS)
+    timestamp = getourtimeofday();
+#endif
+
+    se.sigev_notify = SIGEV_SIGNAL;
+    se.sigev_signo = ITIMER_SIGNAL;
+    se.sigev_value.sival_int = ITIMER_SIGNAL;
+    if (timer_create(CLOCK_VIRTUAL, &se, &tid)) {
+	barf("can't create virtual timer");
+    }
+    it.it_value.tv_sec = 0;
+    it.it_value.tv_nsec = 0;
+    it.it_interval = it.it_value;
+    return timer_settime(tid, TIMER_RELTIME, &it, NULL);
+}
+# endif
+
+#if 0
+/* Currently unused */
+void
+block_vtalrm_signal(void)
+{
+    sigset_t signals;
+    
+    sigemptyset(&signals);
+    sigaddset(&signals, ITIMER_SIGNAL);
+
+    (void) sigprocmask(SIG_BLOCK, &signals, NULL);
+}
+
+void
+unblock_vtalrm_signal(void)
+{
+    sigset_t signals;
+    
+    sigemptyset(&signals);
+    sigaddset(&signals, ITIMER_SIGNAL);
+
+    (void) sigprocmask(SIG_UNBLOCK, &signals, NULL);
+}
+#endif
+
+/* gettimeofday() takes around 1us on our 500MHz PIII.  Since we're
+ * only calling it 50 times/s, it shouldn't have any great impact.
+ */
+lnat
+getourtimeofday(void)
+{
+  struct timeval tv;
+  gettimeofday(&tv, (struct timezone *) NULL);
+  	// cast to lnat because nat may be 64 bit when int is only 32 bit
+  return ((lnat)tv.tv_sec * TICK_FREQUENCY +
+	  (lnat)tv.tv_usec * TICK_FREQUENCY / 1000000);
+}