Author: sewardj
Date: 2008-03-09 01:29:20 +0000 (Sun, 09 Mar 2008)
New Revision: 7604
Log:
Try to address performance problems resulting from increased searching
of the stacks list.
Modified:
branches/HGDEV/coregrind/m_stacks.c
Modified: branches/HGDEV/coregrind/m_stacks.c
===================================================================
--- branches/HGDEV/coregrind/m_stacks.c 2008-03-08 16:54:49 UTC (rev 7603)
+++ branches/HGDEV/coregrind/m_stacks.c 2008-03-09 01:29:20 UTC (rev 7604)
@@ -30,6 +30,7 @@
#include "pub_core_basics.h"
#include "pub_core_debuglog.h"
+#include "pub_core_libcassert.h"
#include "pub_core_libcprint.h"
#include "pub_core_mallocfree.h"
#include "pub_core_options.h"
@@ -98,16 +99,70 @@
*/
static Stack *current_stack;
+/* Find 'st' in the stacks_list and move it one step closer the the
+ front of the list, so as to make subsequent searches for it
+ cheaper. */
+static void move_Stack_one_step_forward ( Stack* st )
+{
+ Stack *st0, *st1, *st2;
+ if (st == stacks)
+ return; /* already at head of list */
+ vg_assert(st != NULL);
+ st0 = stacks;
+ st1 = NULL;
+ st2 = NULL;
+ while (True) {
+ if (st0 == NULL || st0 == st) break;
+ st2 = st1;
+ st1 = st0;
+ st0 = st0->next;
+ }
+ vg_assert(st0 == st);
+ if (st0 != NULL && st1 != NULL && st2 != NULL) {
+ Stack* tmp;
+ /* st0 points to st, st1 to its predecessor, and st2 to st1's
+ predecessor. Swap st0 and st1, that is, move st0 one step
+ closer to the start of the list. */
+ vg_assert(st2->next == st1);
+ vg_assert(st1->next == st0);
+ tmp = st0->next;
+ st2->next = st0;
+ st0->next = st1;
+ st1->next = tmp;
+ }
+ else
+ if (st0 != NULL && st1 != NULL && st2 == NULL) {
+ /* it's second in the list. */
+ vg_assert(stacks == st1);
+ vg_assert(st1->next == st0);
+ st1->next = st0->next;
+ st0->next = st1;
+ stacks = st0;
+ }
+}
+
/* Find what stack an address falls into. */
static Stack* find_stack_by_addr(Addr sp)
{
+ static UWord n_fails = 0;
+ static UWord n_searches = 0;
+ static UWord n_steps = 0;
Stack *i = stacks;
+ n_searches++;
+ if (0 && 0 == (n_searches % 10000))
+ VG_(printf)("(hgdev) %lu searches, %lu steps, %lu fails\n",
+ n_searches, n_steps+1, n_fails);
while (i) {
+ n_steps++;
if (sp >= i->start && sp <= i->end) {
+ if (1 && (n_searches & 0x3F) == 0) {
+ move_Stack_one_step_forward( i );
+ }
return i;
}
i = i->next;
}
+ n_fails++;
return NULL;
}
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