linux-kernel - Re: [PATCH v2 2/5] perf metric: Use NAN for missing event IDs.

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Date:   Thu, 19 Nov 2020 20:47:07 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
        Jin Yao <yao.jin@...ux.intel.com>,
        John Garry <john.garry@...wei.com>,
        Paul Clarke <pc@...ibm.com>, kajoljain <kjain@...ux.ibm.com>,
        Stephane Eranian <eranian@...gle.com>,
        Sandeep Dasgupta <sdasgup@...gle.com>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v2 2/5] perf metric: Use NAN for missing event IDs.

On Tue, Nov 17, 2020 at 09:03:32PM -0800, Ian Rogers wrote:
> If during computing a metric an event (id) is missing the parsing
> aborts. A later patch will make it so that events that aren't used in
> the output are deliberately omitted, in which case we don't want the
> abort. Modify the missing ID case to report NAN for these cases.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/util/expr.y | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
> index b2ada8f8309a..c22e3500a40f 100644
> --- a/tools/perf/util/expr.y
> +++ b/tools/perf/util/expr.y
> @@ -1,6 +1,7 @@
>  /* Simple expression parser */
>  %{
>  #define YYDEBUG 1
> +#include <math.h>
>  #include <stdio.h>
>  #include "util.h"
>  #include "util/debug.h"
> @@ -89,8 +90,7 @@ expr:	  NUMBER
>  					struct expr_id_data *data;
>  
>  					if (expr__resolve_id(ctx, $1, &data)) {
> -						free($1);
> -						YYABORT;
> +						$$ = NAN;

hum, it's directly overwriten in the next line, no?

jirka

>  					}
>  
>  					$$ = expr_id_data__value(data);

> -- 
> 2.29.2.299.gdc1121823c-goog
>