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Fix disable in arbitrary fork/join situations.

This commit is contained in:
steve 2002-09-21 04:55:00 +00:00
parent ab94b0a636
commit acd5e86e04
1 changed files with 84 additions and 58 deletions
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142
vvp/vthread.cc
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@ -17,7 +17,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#ifdef HAVE_CVS_IDENT
#ident "$Id: vthread.cc,v 1.87 2002/09/20 03:59:34 steve Exp $"
#ident "$Id: vthread.cc,v 1.88 2002/09/21 04:55:00 steve Exp $"
#endif
# include "vthread.h"
@ -72,7 +72,7 @@
*
* A --> C(zombie) --> X --> B
*
* If A then executes 2 %joins, it will read C and X (when it ends)
* If A then executes 2 %joins, it will reap C and X (when it ends)
* leaving B in purgatory. What's worse, A will block on the schedules
* of X and C instead of C and B, possibly creating incorrect timing.
*
@ -103,6 +103,7 @@ struct vthread_s {
unsigned i_have_ended :1;
unsigned waiting_for_event :1;
unsigned is_scheduled :1;
unsigned fork_count :8;
/* This points to the sole child of the thread. */
struct vthread_s*child;
/* This points to my parent, if I have one. */
@ -213,7 +214,7 @@ vthread_t vthread_new(unsigned long pc, struct __vpiScope*scope)
thr->nbits = 4 * (CPU_WORD_BITS/2);
thr->child = 0;
thr->parent = 0;
thr->wait_next = 0;
thr->wait_next = 0;
/* If the target scope never held a thread, then create a
header cell for it. This is a stub to make circular lists
@ -241,6 +242,7 @@ vthread_t vthread_new(unsigned long pc, struct __vpiScope*scope)
thr->i_have_ended = 0;
thr->waiting_for_event = 0;
thr->is_scheduled = 0;
thr->fork_count = 0;
thr_put_bit(thr, 0, 0);
thr_put_bit(thr, 1, 1);
@ -261,10 +263,14 @@ static void vthread_reap(vthread_t thr)
free(thr->bits);
thr->bits = 0;
if (thr->child)
if (thr->child) {
assert(thr->child->parent == thr);
thr->child->parent = thr->parent;
if (thr->parent)
}
if (thr->parent) {
assert(thr->parent->child == thr);
thr->parent->child = thr->child;
}
thr->child = 0;
thr->parent = 0;
@ -277,8 +283,10 @@ static void vthread_reap(vthread_t thr)
/* If this thread is not scheduled, then is it safe to delete
it now. Otherwise, let the schedule event (which will
execute the thread at of_ZOMBIE) delete the object. */
if (thr->is_scheduled == 0)
if ((thr->is_scheduled == 0) && (thr->waiting_for_event == 0)) {
assert(thr->fork_count == 0);
delete thr;
}
}
void vthread_mark_scheduled(vthread_t thr)
@ -752,6 +760,60 @@ bool of_DELAYX(vthread_t thr, vvp_code_t cp)
return false;
}
static bool do_disable(vthread_t thr, vthread_t match)
{
bool flag = false;
/* Pull the target thread out of its scope. */
thr->scope_next->scope_prev = thr->scope_prev;
thr->scope_prev->scope_next = thr->scope_next;
/* Turn the thread off by setting is program counter to
zero and setting an OFF bit. */
thr->pc = 0;
thr->i_have_ended = 1;
/* Turn off all the children of the thread. Simulate a %join
for as many times as needed to clear the results of all the
%forks that this thread has done. */
while (thr->fork_count > 0) {
vthread_t tmp = thr->child;
assert(tmp);
assert(tmp->parent == thr);
tmp->schedule_parent_on_end = 0;
if (do_disable(tmp, match))
flag = true;
thr->fork_count -= 1;
vthread_reap(tmp);
}
if (thr->schedule_parent_on_end) {
/* If a parent is waiting in a %join, wake it up. */
assert(thr->parent);
assert(thr->parent->fork_count > 0);
assert(thr->waiting_for_event == 0);
thr->parent->fork_count -= 1;
schedule_vthread(thr->parent, 0, true);
vthread_reap(thr);
} else if (thr->parent) {
/* If the parent is yet to %join me, let its %join
do the reaping. */
//assert(tmp->is_scheduled == 0);
} else {
/* No parent at all. Goodby. */
vthread_reap(thr);
}
return flag || (thr == match);
}
/*
* Implement the %disable instruction by scanning the target scope for
* all the target threads. Kill the target threads and wake up a
@ -770,63 +832,14 @@ bool of_DISABLE(vthread_t thr, vvp_code_t cp)
while (head->scope_next != head) {
vthread_t tmp = head->scope_next;
/* Pull the target thread out of the scope. */
tmp->scope_next->scope_prev = tmp->scope_prev;
tmp->scope_prev->scope_next = tmp->scope_next;
/* If I am disabling myself, that remember that fact so
that I can finish this statement differently. */
if (tmp == thr)
disabled_myself_flag = true;
/* Turn the thread off by setting is program counter to
zero and setting an OFF bit. */
tmp->pc = 0;
tmp->i_have_ended = 1;
/* Turn off all the children of the thread. */
vthread_t child = tmp->child;
while (child) {
/* XXXX Don't know how to disable waiting children. */
assert(child->waiting_for_event == 0);
child->pc = 0;
child->i_have_ended = 1;
vthread_t next = child->child;
vthread_reap(child);
child = next;
}
if (tmp->schedule_parent_on_end) {
/* If a parent is waiting in a %join, wake it up. */
assert(tmp->parent);
assert(tmp->waiting_for_event == 0);
schedule_vthread(tmp->parent, 0, true);
vthread_reap(tmp);
} else if (tmp->parent) {
/* If the parent is yet to %join me, let its %join
do the reaping. */
//assert(tmp->is_scheduled == 0);
} else if (tmp->waiting_for_event) {
/* If the thread is waiting for an event, then
temporarily mark it as scheduled, so that the
reap detaches it from everything, but does not
delete it. The %zombie function will then
delete the thread when the event trips. */
tmp->is_scheduled = 1;
vthread_reap(tmp);
tmp->is_scheduled = 0;
} else {
/* No parent at all. Goodby. */
vthread_reap(tmp);
}
if (do_disable(tmp, thr))
disabled_myself_flag = true;
}
return ! disabled_myself_flag;
@ -1167,7 +1180,7 @@ bool of_DIV_S(vthread_t thr, vvp_code_t cp)
bool of_END(vthread_t thr, vvp_code_t)
{
assert(! thr->waiting_for_event);
assert( thr->fork_count == 0 );
thr->i_have_ended = 1;
thr->pc = 0;
@ -1176,6 +1189,9 @@ bool of_END(vthread_t thr, vvp_code_t)
%join for the parent. */
if (thr->schedule_parent_on_end) {
assert(thr->parent);
assert(thr->parent->fork_count > 0);
thr->parent->fork_count -= 1;
schedule_vthread(thr->parent, 0, true);
vthread_reap(thr);
return false;
@ -1217,6 +1233,9 @@ bool of_FORK(vthread_t thr, vvp_code_t cp)
assert(child->child->parent == thr);
child->child->parent = child;
}
thr->fork_count += 1;
schedule_vthread(child, 0, true);
return true;
}
@ -1348,8 +1367,12 @@ bool of_JOIN(vthread_t thr, vvp_code_t cp)
assert(thr->child);
assert(thr->child->parent == thr);
assert(thr->fork_count > 0);
/* If the child has already ended, reap it now. */
if (thr->child->i_have_ended) {
thr->fork_count -= 1;
vthread_reap(thr->child);
return true;
}
@ -2401,6 +2424,9 @@ bool of_CALL_UFUNC(vthread_t thr, vvp_code_t cp)
/*
* $Log: vthread.cc,v $
* Revision 1.88 2002/09/21 04:55:00 steve
* Fix disable in arbitrary fork/join situations.
*
* Revision 1.87 2002/09/20 03:59:34 steve
* disable threads with children.
*