Re: [PATCH 1/4] perf expr: Add parsing support for multiple expressions

From: Ian Rogers
Date: Wed May 13 2020 - 02:50:33 EST

On Mon, May 11, 2020 at 1:54 PM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> Adding support to parse metric difinitions in following form:

Typo on definitions.

> NAME = EXPRESSION ;
> NAME = EXPRESSION ;
> ...
>
> The parsed NAME and EXPRESSION will be used in following
> changes to feed the metric code with definitions from
> custom file.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> tools/perf/tests/expr.c | 13 +++++++++++++
> tools/perf/util/expr.c | 6 ++++++
> tools/perf/util/expr.h | 19 +++++++++++++++++--
> tools/perf/util/expr.l | 12 ++++++++++++
> tools/perf/util/expr.y | 13 ++++++++++++-
> 5 files changed, 60 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/tests/expr.c b/tools/perf/tests/expr.c
> index f9e8e5628836..c62e122fe719 100644
> --- a/tools/perf/tests/expr.c
> +++ b/tools/perf/tests/expr.c
> @@ -71,5 +71,18 @@ int test__expr(struct test *t __maybe_unused, int subtest __maybe_unused)
> zfree(&other[i]);
> free((void *)other);
>
> + expr__ctx_init(&ctx);
> + ret = expr__parse_custom(&ctx, "IPC=INSTRUCTIONS / CYCLES; CPI=CYCLES / INSTRUCTIONS;");
> + TEST_ASSERT_VAL("parse custom failed", ret == 0);
> + TEST_ASSERT_VAL("parse custom count", ctx.num_custom == 2);
> + TEST_ASSERT_VAL("parse custom name", !strcmp(ctx.custom[0].name, "IPC"));
> + TEST_ASSERT_VAL("parse custom name", !strcmp(ctx.custom[1].name, "CPI"));
> + TEST_ASSERT_VAL("parse custom expr", !strcmp(ctx.custom[0].expr, "INSTRUCTIONS / CYCLES"));
> + TEST_ASSERT_VAL("parse custom expr", !strcmp(ctx.custom[1].expr, "CYCLES / INSTRUCTIONS"));
> +
> + for (i = 0; i < ctx.num_custom; i++) {
> + zfree(&ctx.custom[i].name);
> + zfree(&ctx.custom[i].expr);
> + }
> return 0;
> }
> diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
> index 8b4ce704a68d..d744cb15c1d4 100644
> --- a/tools/perf/util/expr.c
> +++ b/tools/perf/util/expr.c
> @@ -23,6 +23,7 @@ void expr__add_id(struct expr_parse_ctx *ctx, const char *name, double val)
> void expr__ctx_init(struct expr_parse_ctx *ctx)
> {
> ctx->num_ids = 0;
> + ctx->num_custom = 0;
> }
>
> static int
> @@ -61,6 +62,11 @@ int expr__parse(double *final_val, struct expr_parse_ctx *ctx, const char *expr,
> return __expr__parse(final_val, ctx, expr, EXPR_PARSE, runtime) ? -1 : 0;
> }
>
> +int expr__parse_custom(struct expr_parse_ctx *ctx, const char *expr)
> +{
> + return __expr__parse(NULL, ctx, expr, EXPR_CUSTOM, 0);
> +}
> +
> static bool
> already_seen(const char *val, const char *one, const char **other,
> int num_other)
> diff --git a/tools/perf/util/expr.h b/tools/perf/util/expr.h
> index 40fc452b0f2b..ef116b58a5d4 100644
> --- a/tools/perf/util/expr.h
> +++ b/tools/perf/util/expr.h
> @@ -4,15 +4,29 @@
>
> #define EXPR_MAX_OTHER 64
> #define MAX_PARSE_ID EXPR_MAX_OTHER
> +#define EXPR_MAX 20

Currently deduplication of ids is done after rather than during
expression pasing, meaning hitting these limits is quite easy. This is
fixed in:
https://lore.kernel.org/lkml/20200508053629.210324-8-irogers@xxxxxxxxxx/
But not for custom expressions being added here. I plan to rebase that
work and clone hashmap from libbpf into libapi to workaround the
dependency issue.
That patch also adds expr__ctx_clear as a convenience for cleaning up
the context, and passes the context around inside of metricgroup
rather than ids.

> struct expr_parse_id {
> const char *name;
> double val;
> };
>
> +struct expr_parse_custom {
> + const char *name;
> + const char *expr;
> +};
> +
> struct expr_parse_ctx {
> - int num_ids;
> - struct expr_parse_id ids[MAX_PARSE_ID];
> + union {
> + struct {
> + int num_ids;
> + struct expr_parse_id ids[MAX_PARSE_ID];
> + };
> + struct {
> + int num_custom;
> + struct expr_parse_custom custom[EXPR_MAX];
> + };
> + };
> };
>
> struct expr_scanner_ctx {
> @@ -23,6 +37,7 @@ struct expr_scanner_ctx {
> void expr__ctx_init(struct expr_parse_ctx *ctx);
> void expr__add_id(struct expr_parse_ctx *ctx, const char *id, double val);
> int expr__parse(double *final_val, struct expr_parse_ctx *ctx, const char *expr, int runtime);
> +int expr__parse_custom(struct expr_parse_ctx *ctx, const char *expr);
> int expr__find_other(const char *expr, const char *one, const char ***other,
> int *num_other, int runtime);
>
> diff --git a/tools/perf/util/expr.l b/tools/perf/util/expr.l
> index ceab11bea6f9..c6a930ed22e6 100644
> --- a/tools/perf/util/expr.l
> +++ b/tools/perf/util/expr.l
> @@ -81,12 +81,15 @@ static int str(yyscan_t scanner, int token, int runtime)
> }
> %}
>
> +%x custom
> +
> number [0-9]*\.?[0-9]+
>
> sch [-,=]
> spec \\{sch}
> sym [0-9a-zA-Z_\.:@?]+
> symbol ({spec}|{sym})+
> +all [^;]+
>
> %%
> struct expr_scanner_ctx *sctx = expr_get_extra(yyscanner);
> @@ -100,6 +103,12 @@ symbol ({spec}|{sym})+
> }
> }
>
> +<custom>{
> +
> +{all} { BEGIN(INITIAL); return str(yyscanner, ALL, sctx->runtime); }
> +
> +}
> +
> max { return MAX; }
> min { return MIN; }
> if { return IF; }
> @@ -118,6 +127,9 @@ else { return ELSE; }
> "(" { return '('; }
> ")" { return ')'; }
> "," { return ','; }
> +";" { return ';'; }
> +"=" { BEGIN(custom); return '='; }

Will this interfere with the \\= encoded in MetricExpr? Could you test with:
https://lore.kernel.org/lkml/20200513062752.3681-2-irogers@xxxxxxxxxx/

> +\n { }
> . { }
> %%
>
> diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
> index 21e82a1e11a2..0521e48fa5e3 100644
> --- a/tools/perf/util/expr.y
> +++ b/tools/perf/util/expr.y
> @@ -24,9 +24,10 @@
> char *str;
> }
>
> -%token EXPR_PARSE EXPR_OTHER EXPR_ERROR
> +%token EXPR_PARSE EXPR_OTHER EXPR_CUSTOM EXPR_ERROR
> %token <num> NUMBER
> %token <str> ID
> +%token <str> ALL

Missing %destructor, fix is here:
https://lore.kernel.org/lkml/20200513000318.15166-1-irogers@xxxxxxxxxx/

Thanks,
Ian

> %token MIN MAX IF ELSE SMT_ON
> %left MIN MAX IF
> %left '|'
> @@ -66,6 +67,16 @@ start:
> EXPR_PARSE all_expr
> |
> EXPR_OTHER all_other
> +|
> +EXPR_CUSTOM all_custom
> +
> +all_custom: all_custom ID '=' ALL ';'
> +{
> + ctx->custom[ctx->num_custom].name = $2;
> + ctx->custom[ctx->num_custom].expr = $4;
> + ctx->num_custom++;
> +}
> +|
>
> all_other: all_other other
> |
> --
> 2.25.4
>