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Subject[RFC][PATCH 08/12] tracing/filter: Optimize short ciruit check
From: Steven Rostedt <srostedt@redhat.com>

The test if we should break out early for OR and AND operations
can be optimized by comparing the current result with
(pred->op == OP_OR)

That is if the result is true and the op is an OP_OR, or
if the result is false and the op is not an OP_OR (thus an OP_AND)
we can break out early in either case. Otherwise we continue
processing.

Cc: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_events_filter.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 2677924..afe59ab 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -426,9 +426,15 @@ int filter_match_preds(struct event_filter *filter, void *rec)
pred->parent, &move);
continue;
case MOVE_UP_FROM_LEFT:
- /* Check for short circuits */
- if ((match && pred->op == OP_OR) ||
- (!match && pred->op == OP_AND)) {
+ /*
+ * Check for short circuits.
+ *
+ * Optimization: !!match == (pred->op == OP_OR)
+ * is the same as:
+ * if ((match && pred->op == OP_OR) ||
+ * (!match && pred->op == OP_AND))
+ */
+ if (!!match == (pred->op == OP_OR))
if (pred == root)
break;
pred = get_pred_parent(pred, preds,
--
1.7.2.3



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