On Fri, Nov 22, 2013 at 10:28:52AM +0100, Jakub Jelinek wrote:
> Hi!
>
> Working virtually out of Pago Pago right now.
>
> In C++, falling through the end of a function that returns a value
> without returning a value is undefined behavior (unlike C?), so this patch
> implements instrumentation of it.
I think we really want to have this in for C99+ as well, mainly
because C99 removed implicit int rule.
> --- gcc/ubsan.c.jj 2013-11-22 01:40:03.000000000 +0100
> +++ gcc/ubsan.c 2013-11-22 10:05:29.491725405 +0100
> @@ -227,8 +227,8 @@ ubsan_source_location (location_t loc)
> xloc = expand_location (loc);
>
> /* Fill in the values from LOC. */
> - size_t len = strlen (xloc.file);
> - tree str = build_string (len + 1, xloc.file);
> + size_t len = xloc.file ? strlen (xloc.file) : 0;
> + tree str = build_string (len + 1, xloc.file ? xloc.file : "");
This shouldn't be needed - the ubsan_source_location call is guarded
by if (loc != UNKNOWN_LOCATION). But it doesn't hurt either.
> --- gcc/c-family/c-ubsan.c.jj 2013-11-19 21:56:20.000000000 +0100
> +++ gcc/c-family/c-ubsan.c 2013-11-22 09:52:31.810642606 +0100
> @@ -179,3 +179,14 @@ ubsan_instrument_vla (location_t loc, tr
>
> return t;
> }
> +
> +/* Instrument missing return in C++ functions returning non-void. */
> +
> +tree
> +ubsan_instrument_return (location_t loc)
> +{
> + tree data = ubsan_create_data ("__ubsan_missing_return_data", loc,
> + NULL,NULL_TREE);
Missing space after NULL.
Otherwise the ubsan bits are ok.
Recently I tried to implement this one, too, but I instead tweaked
execute_warn_function_return in tree-cfg.c. It was something
along the lines of (only tree-cfg.c changes here):
--- gcc/tree-cfg.c.mp2 2013-11-22 12:42:13.452426763 +0100
+++ gcc/tree-cfg.c 2013-11-22 13:56:41.051581885 +0100
@@ -8090,9 +8090,16 @@ execute_warn_function_return (void)
{
location = gimple_location (last);
if (location == UNKNOWN_LOCATION)
- location = cfun->function_end_locus;
- warning_at (location, OPT_Wreturn_type, "control reaches end of
non-void function");
+ location = cfun->function_end_locus;
+ warning_at (location, OPT_Wreturn_type, "control reaches end "
+ "of non-void function");
TREE_NO_WARNING (cfun->decl) = 1;
+ if (flag_sanitize & SANITIZE_RETURN)
+ {
+ gimple_stmt_iterator gsi = gsi_for_stmt (last);
+ gsi_insert_before (&gsi, ubsan_instrument_return (location),
+ GSI_SAME_STMT);
+ }
break;
}
}
Marek
