[tip:perf/core] perf annotate: Add comment clarifying how the source code line is parsed

[tip-bot for Arnaldo Carvalho de Melo]

Commit-ID:  ed7b339fb570749042332169e62541b208fc4296
Gitweb:     http://git.kernel.org/tip/ed7b339fb570749042332169e62541b208fc4296
Author:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Tue, 21 Mar 2017 16:00:50 -0300
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 21 Mar 2017 16:00:50 -0300

perf annotate: Add comment clarifying how the source code line is parsed

The source code line number (lineno) needs to be kept in accross calls
to symbol__parse_objdump_line() when parsing the output of 'objdump -l
-dS', so that it can associate it with the instructions till the next
line.

See disasm_line__new() and struct disasm_line::line_nr.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Taeung Song <treeze.taeung@xxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-7hpx8f8ybdpiujceysaj229w@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/annotate.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 4d325cd..22cd1db 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1482,6 +1482,12 @@ int symbol__disassemble(struct symbol *sym, struct map *map, const char *arch_na
 
 	nline = 0;
 	while (!feof(file)) {
+		/*
+		 * The source code line number (lineno) needs to be kept in
+		 * accross 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, map, arch, file, privsize,
 			    &lineno) < 0)
 			break;