Commit 9be27a5d authored May 01, 2020 by Ian Rogers Committed by Arnaldo Carvalho de Melo May 28, 2020

perf expr: Print a debug message for division by zero



If an expression yields 0 and is then divided-by/modulus-by then the
parsing aborts. Add a debug error message to better enable debugging
when this happens.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Haiyan Song <haiyanx.song@intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20200501173333.227162-11-irogers@google.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent f2682a8f

tools/perf/util/expr.y

+12 −2

Original line number	Diff line number	Diff line
		@@ -103,8 +103,18 @@ expr: NUMBER
		\| 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; $$ = (long)$1 % (long)$3; }
		\| expr '/' expr { if ($3 == 0) {
		pr_debug("division by zero\n");
		YYABORT;
		}
		$$ = $1 / $3;
		}
		\| expr '%' expr { if ((long)$3 == 0) {
		pr_debug("division by zero\n");
		YYABORT;
		}
		$$ = (long)$1 % (long)$3;
		}
		\| '-' expr %prec NEG { $$ = -$2; }
		\| '(' if_expr ')' { $$ = $2; }
		\| MIN '(' expr ',' expr ')' { $$ = $3 < $5 ? $3 : $5; }

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