Messages in this thread | | | Date | Thu, 23 Apr 2020 13:28:37 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH v2 10/11] perf expr: print a debug message for division by zero |
| |
On Wed, Apr 22, 2020 at 03:04:29PM -0700, Ian Rogers wrote: > 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) {
is that (long) cast necessary? it's missing for the '/' case
jirka
> + 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; } > -- > 2.26.2.303.gf8c07b1a785-goog >
| |