[PATCH 1/5] perf annotate: avoid reallocation in objdump parsing

Ian Rogers
2019-10-10T18:37:12Z

Objdump output is parsed using getline which allocates memory for the
read. Getline will realloc if the memory is too small, but currently the
line is always freed after the call.
Simplify parse_objdump_line by performing the reading in symbol__disassemble.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/annotate.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index e830eadfca2a..1487849a191a 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1485,24 +1485,17 @@ annotation_line__print(struct annotation_line *al, struct symbol *sym, u64 start
* means that it's not a disassembly line so should be treated differently.
* The ops.raw part will be parsed further according to type of the instruction.
*/
-static int symbol__parse_objdump_line(struct symbol *sym, FILE *file,
+static int symbol__parse_objdump_line(struct symbol *sym,
struct annotate_args *args,
- int *line_nr)
+ char *line, int *line_nr)
{
struct map *map = args->ms.map;
struct annotation *notes = symbol__annotation(sym);
struct disasm_line *dl;
- char *line = NULL, *parsed_line, *tmp, *tmp2;
- size_t line_len;
+ char *parsed_line, *tmp, *tmp2;
s64 line_ip, offset = -1;
regmatch_t match[2];

- if (getline(&line, &line_len, file) < 0)
- return -1;
-
- if (!line)
- return -1;
-
line_ip = -1;
parsed_line = strim(line);

@@ -1539,7 +1532,6 @@ static int symbol__parse_objdump_line(struct symbol *sym, FILE *file,
args->ms.sym = sym;

dl = disasm_line__new(args);
- free(line);
(*line_nr)++;

if (dl == NULL)
@@ -1855,6 +1847,8 @@ static int symbol__disassemble(struct symbol *sym, struct annotate_args *args)
int lineno = 0;
int nline;
pid_t pid;
+ char *line;
+ size_t line_len;
int err = dso__disassemble_filename(dso, symfs_filename, sizeof(symfs_filename));

if (err)
@@ -1943,18 +1937,26 @@ static int symbol__disassemble(struct symbol *sym, struct annotate_args *args)
goto out_free_command;
}

+ /* Storage for getline. */
+ line = NULL;
+ line_len = 0;
+
nline = 0;
while (!feof(file)) {
+ if (getline(&line, &line_len, file) < 0 || !line)
+ break;
+
/*
* The source code line number (lineno) needs to be kept in
* across calls to symbol__parse_objdump_line(), so that it
* can associate it with the instructions till the next one.
* See disasm_line__new() and struct disasm_line::line_nr.
*/
- if (symbol__parse_objdump_line(sym, file, args, &lineno) < 0)
+ if (symbol__parse_objdump_line(sym, args, line, &lineno) < 0)
break;
nline++;
}
+ free(line);

if (nline == 0)
pr_err("No output from %s\n", command);
--
2.23.0.581.g78d2f28ef7-goog