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[trans-mem] PR46653: handle identical log entries in hash
- From: Aldy Hernandez <aldyh at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org, rth at redhat dot com
- Date: Mon, 29 Nov 2010 09:39:29 -0500
- Subject: [trans-mem] PR46653: handle identical log entries in hash
operand_equal_p() will return false for volatiles, even if they are exactly
the same pointer because of the side-effects. This causes problems when
we search for an existing hash slot, because we never match ourselves.
Fixed thus.
OK for branch?
PR/46653
* trans-mem.c (tm_log_eq): Return true for identical addresses.
Index: testsuite/g++.dg/tm/pr46653.C
===================================================================
--- testsuite/g++.dg/tm/pr46653.C (revision 0)
+++ testsuite/g++.dg/tm/pr46653.C (revision 0)
@@ -0,0 +1,18 @@
+// { dg-do compile }
+// { dg-options "-fgnu-tm -O" }
+
+class shared_count
+{
+public:
+ volatile int j;
+ shared_count() : j(0) { }
+};
+
+shared_count * c;
+int main()
+{
+ __transaction [[atomic]] {
+ shared_count sc;
+ }
+ return 0;
+}
Index: trans-mem.c
===================================================================
--- trans-mem.c (revision 167111)
+++ trans-mem.c (working copy)
@@ -860,6 +860,13 @@ tm_log_eq (const void *p1, const void *p
{
const struct tm_log_entry *log1 = (const struct tm_log_entry *) p1;
const struct tm_log_entry *log2 = (const struct tm_log_entry *) p2;
+
+ /* Special case plain equality because operand_equal_p() below will
+ return FALSE if the addresses are equal but they have
+ side-effects (e.g. a volatile address). */
+ if (log1->addr == log2->addr)
+ return true;
+
return operand_equal_p (log1->addr, log2->addr, 0);
}