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    SubjectRe: [PATCH v1 07/15] perf, tools: Expression parser enhancements for metrics
    On Mon, Jul 24, 2017 at 04:40:07PM -0700, Andi Kleen wrote:
    > From: Andi Kleen <ak@linux.intel.com>
    >
    > 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@linux.intel.com>
    > ---
    > 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
    >

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