linux-kernel - Re: [PATCH v2 06/11] perf expr: parse numbers as doubles

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Date:   Mon, 27 Apr 2020 16:41:46 +0530
From:   kajoljain <kjain@...ux.ibm.com>
To:     Ian Rogers <irogers@...gle.com>,
        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>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Haiyan Song <haiyanx.song@...el.com>,
        Jin Yao <yao.jin@...ux.intel.com>,
        Song Liu <songliubraving@...com>,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        John Garry <john.garry@...wei.com>,
        Leo Yan <leo.yan@...aro.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Paul Clarke <pc@...ibm.com>, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org
Cc:     Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v2 06/11] perf expr: parse numbers as doubles



On 4/23/20 3:34 AM, Ian Rogers wrote:
> This is expected in expr.y and metrics use floating point values such as
> x86 broadwell IFetch_Line_Utilization.
> 
> Fixes: 26226a97724d (perf expr: Move expr lexer to flex)
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/util/expr.l | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/util/expr.l b/tools/perf/util/expr.l
> index 95bcf3629edf..0efda2ce2766 100644
> --- a/tools/perf/util/expr.l
> +++ b/tools/perf/util/expr.l
> @@ -10,12 +10,12 @@
>  char *expr_get_text(yyscan_t yyscanner);
>  YYSTYPE *expr_get_lval(yyscan_t yyscanner);
>  
> -static int __value(YYSTYPE *yylval, char *str, int base, int token)
> +static double __value(YYSTYPE *yylval, char *str, int token)
>  {
> -	u64 num;
> +	double num;
>  
>  	errno = 0;
> -	num = strtoull(str, NULL, base);
> +	num = strtod(str, NULL);
>  	if (errno)
>  		return EXPR_ERROR;
>  
> @@ -23,12 +23,12 @@ static int __value(YYSTYPE *yylval, char *str, int base, int token)
>  	return token;
>  }
>  
> -static int value(yyscan_t scanner, int base)
> +static int value(yyscan_t scanner)
>  {
>  	YYSTYPE *yylval = expr_get_lval(scanner);
>  	char *text = expr_get_text(scanner);
>  
> -	return __value(yylval, text, base, NUMBER);
> +	return __value(yylval, text, NUMBER);
>  }
>  
>  /*
> @@ -68,7 +68,7 @@ static int str(yyscan_t scanner, int token)
>  }
>  %}
>  
> -number		[0-9]+
> +number		[0-9]*\.?[0-9]+
>  

Hi Ian,
    In this patch I saw the parsing of expression with '+number		[0-9]*\.?[0-9]+' 
Could you please explain why '?' is introduced here, so that I can be sure that this is
not conflicting with my change to add '?'

In this patch : https://lkml.org/lkml/2020/4/1/1427
I have used '?' symbol as part of metric expression in order to replace '?' with runtime
parameter. 

Thanks,
Kajol Jain


>  sch		[-,=]
>  spec		\\{sch}
> @@ -92,7 +92,7 @@ min		{ return MIN; }
>  if		{ return IF; }
>  else		{ return ELSE; }
>  #smt_on		{ return SMT_ON; }
> -{number}	{ return value(yyscanner, 10); }
> +{number}	{ return value(yyscanner); }
>  {symbol}	{ return str(yyscanner, ID); }
>  "|"		{ return '|'; }
>  "^"		{ return '^'; }
>