On 10/30/2013 12:15 PM, Marek Polacek wrote:
On Wed, Oct 30, 2013 at 11:56:25AM -0400, Jason Merrill wrote:
Saving 'size' here doesn't help since it's already been used above.
Could you use itype instead of size here?
I already experimented with that and I think I can't, since we call
the finish_expr_stmt too soon, which results in:
int x = 1;
int a[0:(sizetype) SAVE_EXPR <D.2143>];
<<cleanup_point int x = 1;>>;
<<cleanup_point <<< Unknown tree: expr_stmt
if (SAVE_EXPR <D.2143> <= 0)
{
__builtin___ubsan_handle_vla_bound_not_positive (&*.Lubsan_data0, (unsigned
long) SAVE_EXPR <D.2143>);
}
else
{
0
}, (void) SAVE_EXPR <D.2143>; >>>>>;
ssizetype D.2143;
<<cleanup_point <<< Unknown tree: expr_stmt
(void) (D.2143 = (ssizetype) ++x + -1) >>>>>;
Ah, looks like you're getting an unfortunate interaction with
stabilize_vla_size, which is replacing the contents of the SAVE_EXPR
with a reference to a variable that isn't initialized yet. Perhaps we
should move the stabilize_vla_size call into compute_array_index_type, too.
and that ICEs in gimplify_var_or_parm_decl, presumably because the
if (SAVE_EXPR <D.2143> <= 0) { ... } should be emitted *after* that
cleanup_point. When we generated the C++1y check in cp_finish_decl,
we emitted the check after the cleanup_point, and everything was OK.
I admit I don't understand the cleanup_points very much and I don't
know exactly where they are coming from, because normally I don't see
them coming out of C FE. :)
You can ignore the cleanup_points; they just wrap every full-expression.
Jason
