gcc/libitm/clone.cc

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2022-01-03 10:42:10 +01:00
/* Copyright (C) 2009-2022 Free Software Foundation, Inc.
Contributed by Richard Henderson <rth@redhat.com>.
This file is part of the GNU Transactional Memory Library (libitm).
Libitm is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
Libitm is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
#include "libitm_i.h"
using namespace GTM;
struct clone_entry
{
void *orig, *clone;
};
struct clone_table
{
clone_entry *table;
size_t size;
clone_table *next;
};
static clone_table *all_tables;
static void *
find_clone (void *ptr)
{
clone_table *table;
for (table = all_tables; table ; table = table->next)
{
clone_entry *t = table->table;
size_t lo = 0, hi = table->size, i;
/* Quick test for whether PTR is present in this table. */
if (ptr < t[0].orig || ptr > t[hi - 1].orig)
continue;
/* Otherwise binary search. */
while (lo < hi)
{
i = (lo + hi) / 2;
if (ptr < t[i].orig)
hi = i;
else if (ptr > t[i].orig)
lo = i + 1;
else
return t[i].clone;
}
/* Given the quick test above, if we don't find the entry in
this table then it doesn't exist. */
break;
}
return NULL;
}
void * ITM_REGPARM
_ITM_getTMCloneOrIrrevocable (void *ptr)
{
void *ret = find_clone (ptr);
if (ret)
return ret;
gtm_thr()->serialirr_mode ();
return ptr;
}
void * ITM_REGPARM
_ITM_getTMCloneSafe (void *ptr)
{
void *ret = find_clone (ptr);
if (ret == NULL)
abort ();
return ret;
}
static int
clone_entry_compare (const void *a, const void *b)
{
const clone_entry *aa = (const clone_entry *)a;
const clone_entry *bb = (const clone_entry *)b;
if (aa->orig < bb->orig)
return -1;
else if (aa->orig > bb->orig)
return 1;
else
return 0;
}
namespace {
// Within find_clone, we know that we are inside a transaction. Because
// of that, we have already synchronized with serial_lock. By taking the
// serial_lock for write, we exclude all transactions while we make this
// change to the clone tables, without having to synchronize on a separate
// lock. Do be careful not to attempt a recursive write lock.
class ExcludeTransaction
{
bool do_lock;
public:
ExcludeTransaction()
{
gtm_thread *tx = gtm_thr();
do_lock = !(tx && (tx->state & gtm_thread::STATE_SERIAL));
if (do_lock)
gtm_thread::serial_lock.write_lock ();
}
~ExcludeTransaction()
{
if (do_lock)
gtm_thread::serial_lock.write_unlock ();
}
};
} // end anon namespace
void
_ITM_registerTMCloneTable (void *xent, size_t size)
{
clone_entry *ent = static_cast<clone_entry *>(xent);
clone_table *table;
table = (clone_table *) xmalloc (sizeof (clone_table));
table->table = ent;
table->size = size;
qsort (ent, size, sizeof (clone_entry), clone_entry_compare);
// Hold the serial_lock while we update the ALL_TABLES datastructure.
{
ExcludeTransaction exclude;
table->next = all_tables;
all_tables = table;
}
}
void
_ITM_deregisterTMCloneTable (void *xent)
{
clone_entry *ent = static_cast<clone_entry *>(xent);
clone_table *tab;
// Hold the serial_lock while we update the ALL_TABLES datastructure.
{
ExcludeTransaction exclude;
clone_table **pprev;
for (pprev = &all_tables;
tab = *pprev, tab->table != ent;
pprev = &tab->next)
continue;
*pprev = tab->next;
}
free (tab);
}