linux-kernel - Re: [PATCH V3 0/1] perf tools: Allow config terms with breakpoints

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Date:   Tue, 6 Jun 2023 22:37:03 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH V3 0/1] perf tools: Allow config terms with breakpoints

On 6/06/23 22:22, Arnaldo Carvalho de Melo wrote:
> Em Tue, Jun 06, 2023 at 03:15:59PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Tue, Jun 06, 2023 at 08:00:33AM +0300, Adrian Hunter escreveu:
>>> On 25/05/23 11:29, Adrian Hunter wrote:
>>>> Hi
>>>>
>>>> Here is a patch (V3) to the event parser for breakpoint events.
>>>> I am not that familiar with flex / bison, but it seemed to
>>>> need trailing context to stop the mem event colon and slash
>>>> delimiters from getting mixed up with delimiters for config
>>>> terms or event modifiers.  Please look closely at that.
>>>>
>>>>
>>>> Changes in V3:
>>>>
>>>>       Add Ian's Reviewed-by
>>>>       Re-base
>>>
>>> Still applies.  Any more comments?
>>
>> Tried it now, twice, once after removing the O= build dir:
>>
>>   CC      /tmp/build/perf-tools-next/tests/event-times.o
>>   CC      /tmp/build/perf-tools-next/tests/expr.o
>>   BISON   /tmp/build/perf-tools-next/util/parse-events-bison.c
>> util/parse-events.y:508.24-34: warning: unused value: $3 [-Wother]
>>   508 | PE_PREFIX_MEM PE_VALUE PE_BP_SLASH PE_VALUE PE_BP_COLON PE_MODIFIER_BP opt_event_config
>>       |                        ^~~~~~~~~~~
>> util/parse-events.y:508.45-55: warning: unused value: $5 [-Wother]
>>   508 | PE_PREFIX_MEM PE_VALUE PE_BP_SLASH PE_VALUE PE_BP_COLON PE_MODIFIER_BP opt_event_config
>>       |                                             ^~~~~~~~~~~
>> util/parse-events.y:526.24-34: warning: unused value: $3 [-Wother]
>>   526 | PE_PREFIX_MEM PE_VALUE PE_BP_SLASH PE_VALUE opt_event_config
>>       |                        ^~~~~~~~~~~
>> util/parse-events.y:543.24-34: warning: unused value: $3 [-Wother]
>>   543 | PE_PREFIX_MEM PE_VALUE PE_BP_COLON PE_MODIFIER_BP opt_event_config
>>       |                        ^~~~~~~~~~~
>>   CC      /tmp/build/perf-tools-next/tests/backward-ring-buffer.o
> 
> But it doesn't _break_ the build, just warns thiis when generating the
> .c file, the next build it notices it is already generated, no warnings.

The build script I was using has a flaw.  It doesn't show warnings
unless the build fails, assuming warnings are errors.  But these
are not.

The first hack that came to mind, and seems to work, is:

diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index bbfb8110947c..dd36be3832b6 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -510,6 +510,8 @@ PE_PREFIX_MEM PE_VALUE PE_BP_SLASH PE_VALUE PE_BP_COLON PE_MODIFIER_BP opt_event
 	struct list_head *list;
 	int err;
 
+	$3 = $3;
+	$5 = $5;
 	list = alloc_list();
 	ABORT_ON(!list);
 	err = parse_events_add_breakpoint(_parse_state, list,
@@ -528,6 +530,7 @@ PE_PREFIX_MEM PE_VALUE PE_BP_SLASH PE_VALUE opt_event_config
 	struct list_head *list;
 	int err;
 
+	$3 = $3;
 	list = alloc_list();
 	ABORT_ON(!list);
 	err = parse_events_add_breakpoint(_parse_state, list,
@@ -545,6 +548,7 @@ PE_PREFIX_MEM PE_VALUE PE_BP_COLON PE_MODIFIER_BP opt_event_config
 	struct list_head *list;
 	int err;
 
+	$3 = $3;
 	list = alloc_list();
 	ABORT_ON(!list);
 	err = parse_events_add_breakpoint(_parse_state, list,


> 
> - Arnaldo
>  
>>
>> ⬢[acme@...lbox perf-tools-next]$ cat /etc/redhat-release
>> Fedora release 36 (Thirty Six)
>>
>> ⬢[acme@...lbox perf-tools-next]$ rpm -q bison
>> bison-3.8.2-2.fc36.x86_64
>> ⬢[acme@...lbox perf-tools-next]$ rpm -q flex
>> flex-2.6.4-10.fc36.x86_64
>> ⬢[acme@...lbox perf-tools-next]$
>>
>>
>> - Arnaldo
>>  
>>>>
>>>> Changes in V2:
>>>>
>>>>       Add comments to tools/perf/util/parse-events.l
>>>>       Add a test for 2 mem events back to back with config terms
>>>>
>>>>
>>>> Adrian Hunter (1):
>>>>       perf tools: Allow config terms with breakpoints
>>>>
>>>>  tools/perf/tests/parse-events.c | 157 ++++++++++++++++++++++++++++++++++++++++
>>>>  tools/perf/util/parse-events.c  |  23 +++++-
>>>>  tools/perf/util/parse-events.h  |   6 +-
>>>>  tools/perf/util/parse-events.l  |  23 +++++-
>>>>  tools/perf/util/parse-events.y  |  42 ++++++-----
>>>>  5 files changed, 224 insertions(+), 27 deletions(-)
>>>>
>>>>
>>>> Regards
>>>> Adrian
>>>
>>
>> -- 
>>
>> - Arnaldo
>