[PATCH v4 10/12] perf expr: print a debug message for division by zero

Ian Rogers
2020-05-01T17:34:12Z

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>
---
tools/perf/util/expr.y | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
index 54260094b947..21e82a1e11a2 100644
--- a/tools/perf/util/expr.y
+++ b/tools/perf/util/expr.y
@@ -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; }
--
2.26.2.526.g744177e7f7-goog