On Tue, Jun 7, 2011 at 12:27 PM, Jakub Jelinek <ja...@redhat.com> wrote: > On Tue, Jun 07, 2011 at 12:19:59PM +0200, Richard Guenther wrote: >> On Tue, Jun 7, 2011 at 7:39 AM, Jason Merrill <ja...@redhat.com> wrote: >> > In the testcase, fold_indirect_ref_1 won't fold *(T*)(s1+10) to an >> > ARRAY_REF >> > because T != unsigned. Even if it were just a typedef to unsigned, that >> > isn't close enough, but in this case it's a typedef to const unsigned. >> > >> > I'm not sure what the type coherence rules are for ARRAY_REF. Is it really >> > necessary that the type of the ARRAY_REF match exactly the element type of >> > the array? >> >> I _think_ that you can unconditionally change the code to do >> >> TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2) >> && TYPE_QUALS (t1) == TYPE_QUALS (t2) >> >> now, I'm not sure if for the testcase T and unsigned differ in qualifiers. > > I guess folding into array_ref that way is fine, but you should in the end > fold_convert_loc it to the expected type, while the middle-end has the > notion of useless type conversions, fold-const.c is also used by FEs and > I think it is expected to have the types exactly matching. > So (T)s1[10] instead of s1[10] in this case.
I'm not sure that's a good idea if the caller wants an lvalue. Richard. > Jakub >
