Re: [PATCH v1 07/15] perf, tools: Expression parser enhancements for metrics

[Jiri Olsa]

On Mon, Jul 24, 2017 at 04:40:07PM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> 
> Enhance the expression parser for more complex metric formulas.
> 
> - Support python style IF ELSE operators
> - Support MIN/MAX operations
> - Support | & ^ operators
> - Minor cleanups and fixes
> - Add an #SMT_On magic variable for formulas that depend on the SMT
> status.
> - Support an \ escape for operators. This allows to specify event names
> like c2-residency

please state some examples of this

thanks,
jirka

> - Support @ as an alternative for / to be able to specify pmus without
> conflicts with operators (like msr/tsc/ as msr@tsc@)
> 
> Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> ---
>  tools/perf/tests/expr.c |  5 ++++
>  tools/perf/util/expr.y  | 61 ++++++++++++++++++++++++++++++++++++++++++++-----
>  2 files changed, 60 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/tests/expr.c b/tools/perf/tests/expr.c
> index 6c6a3749aaf6..e75365098f23 100644
> --- a/tools/perf/tests/expr.c
> +++ b/tools/perf/tests/expr.c
> @@ -31,6 +31,11 @@ int test__expr(int subtest __maybe_unused)
>  	ret |= test(&ctx, "(BAR/2)%2", 1);
>  	ret |= test(&ctx, "1 - -4",  5);
>  	ret |= test(&ctx, "(FOO-1)*2 + (BAR/2)%2 - -4",  5);
> +	ret |= test(&ctx, "1-1 | 1", 1);
> +	ret |= test(&ctx, "1-1 & 1", 0);
> +	ret |= test(&ctx, "min(1,2) + 1", 2);
> +	ret |= test(&ctx, "max(1,2) + 1", 3);
> +	ret |= test(&ctx, "1+1 if 3*4 else 0", 2);
>  
>  	if (ret)
>  		return ret;
> diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
> index 953e65ba2cc7..5753c4f21534 100644
> --- a/tools/perf/util/expr.y
> +++ b/tools/perf/util/expr.y
> @@ -4,6 +4,7 @@
>  #include "util/debug.h"
>  #define IN_EXPR_Y 1
>  #include "expr.h"
> +#include "smt.h"
>  #include <string.h>
>  
>  #define MAXIDLEN 256
> @@ -22,13 +23,15 @@
>  
>  %token <num> NUMBER
>  %token <id> ID
> +%token MIN MAX IF ELSE SMT_ON
> +%left MIN MAX IF
>  %left '|'
>  %left '^'
>  %left '&'
>  %left '-' '+'
>  %left '*' '/' '%'
>  %left NEG NOT
> -%type <num> expr
> +%type <num> expr if_expr
>  
>  %{
>  static int expr__lex(YYSTYPE *res, const char **pp);
> @@ -57,7 +60,12 @@ static int lookup_id(struct parse_ctx *ctx, char *id, double *val)
>  %}
>  %%
>  
> -all_expr: expr			{ *final_val = $1; }
> +all_expr: if_expr			{ *final_val = $1; }
> +	;
> +
> +if_expr:
> +	expr IF expr ELSE expr { $$ = $3 ? $1 : $5; }
> +	| expr
>  	;
>  
>  expr:	  NUMBER
> @@ -66,13 +74,19 @@ expr:	  NUMBER
>  					YYABORT;
>  				  }
>  				}
> +	| expr '|' expr		{ $$ = (long)$1 | (long)$3; }
> +	| expr '&' expr		{ $$ = (long)$1 & (long)$3; }
> +	| expr '^' expr		{ $$ = (long)$1 ^ (long)$3; }
>  	| expr '+' expr		{ $$ = $1 + $3; }
>  	| expr '-' expr		{ $$ = $1 - $3; }
>  	| expr '*' expr		{ $$ = $1 * $3; }
>  	| expr '/' expr		{ if ($3 == 0) YYABORT; $$ = $1 / $3; }
>  	| expr '%' expr		{ if ((long)$3 == 0) YYABORT; $$ = (long)$1 % (long)$3; }
>  	| '-' expr %prec NEG	{ $$ = -$2; }
> -	| '(' expr ')'		{ $$ = $2; }
> +	| '(' if_expr ')'	{ $$ = $2; }
> +	| MIN '(' expr ',' expr ')' { $$ = $3 < $5 ? $3 : $5; }
> +	| MAX '(' expr ',' expr ')' { $$ = $3 > $5 ? $3 : $5; }
> +	| SMT_ON		 { $$ = smt_on() > 0; }
>  	;
>  
>  %%
> @@ -82,13 +96,47 @@ static int expr__symbol(YYSTYPE *res, const char *p, const char **pp)
>  	char *dst = res->id;
>  	const char *s = p;
>  
> -	while (isalnum(*p) || *p == '_' || *p == '.') {
> +	if (*p == '#')
> +		*dst++ = *p++;
> +
> +	while (isalnum(*p) || *p == '_' || *p == '.' || *p == ':' || *p == '@' || *p == '\\') {
>  		if (p - s >= MAXIDLEN)
>  			return -1;
> -		*dst++ = *p++;
> +		/*
> +		 * Allow @ instead of / to be able to specify pmu/event/ without
> +		 * conflicts with normal division.
> +		 */
> +		if (*p == '@')
> +			*dst++ = '/';
> +		else if (*p == '\\')
> +			*dst++ = *++p;
> +		else
> +			*dst++ = *p;
> +		p++;
>  	}
>  	*dst = 0;
>  	*pp = p;
> +	dst = res->id;
> +	switch (dst[0]) {
> +	case 'm':
> +		if (!strcmp(dst, "min"))
> +			return MIN;
> +		if (!strcmp(dst, "max"))
> +			return MAX;
> +		break;
> +	case 'i':
> +		if (!strcmp(dst, "if"))
> +			return IF;
> +		break;
> +	case 'e':
> +		if (!strcmp(dst, "else"))
> +			return ELSE;
> +		break;
> +	case '#':
> +		if (!strcasecmp(dst, "#smt_on"))
> +			return SMT_ON;
> +		break;
> +	}
>  	return ID;
>  }
>  
> @@ -102,6 +150,7 @@ static int expr__lex(YYSTYPE *res, const char **pp)
>  		p++;
>  	s = p;
>  	switch (*p++) {
> +	case '#':
>  	case 'a' ... 'z':
>  	case 'A' ... 'Z':
>  		return expr__symbol(res, p - 1, pp);
> @@ -151,7 +200,7 @@ int expr__find_other(const char *p, const char *one, const char ***other,
>  			err = 0;
>  			break;
>  		}
> -		if (tok == ID && strcasecmp(one, val.id)) {
> +		if (tok == ID && (!one || strcasecmp(one, val.id))) {
>  			if (num_other >= EXPR_MAX_OTHER - 1) {
>  				pr_debug("Too many extra events in %s\n", orig);
>  				break;
> -- 
> 2.9.4
>