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[v3,5/9] perf tools: avoid a malloc for array events

Message ID 20191024190202.109403-6-irogers@google.com
State Not Applicable
Delegated to: BPF Maintainers
Headers show
Series Improvements to memory usage by parse events | expand

Commit Message

Ian Rogers Oct. 24, 2019, 7:01 p.m. UTC 
Use realloc rather than malloc+memcpy to possibly avoid a memory
allocation when appending array elements.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/parse-events.y | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)
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Patch

diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 26cb65798522..545ab7cefc20 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -691,14 +691,12 @@  array_terms ',' array_term
 	struct parse_events_array new_array;
 
 	new_array.nr_ranges = $1.nr_ranges + $3.nr_ranges;
-	new_array.ranges = malloc(sizeof(new_array.ranges[0]) *
-				  new_array.nr_ranges);
+	new_array.ranges = realloc($1.ranges,
+				sizeof(new_array.ranges[0]) *
+				new_array.nr_ranges);
 	ABORT_ON(!new_array.ranges);
-	memcpy(&new_array.ranges[0], $1.ranges,
-	       $1.nr_ranges * sizeof(new_array.ranges[0]));
 	memcpy(&new_array.ranges[$1.nr_ranges], $3.ranges,
 	       $3.nr_ranges * sizeof(new_array.ranges[0]));
-	free($1.ranges);
 	free($3.ranges);
 	$$ = new_array;
 }