http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50294
--- Comment #10 from rguenther at suse dot de <rguenther at suse dot de> 2011-12-01 09:34:31 UTC --- On Sat, 19 Nov 2011, ebotcazou at gcc dot gnu.org wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50294 > > --- Comment #9 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-11-19 > 21:35:48 UTC --- > > Thus the question - what should stor-layout do with domain types > > that wrap the wrong way around (i.e. are of wrong type because Ada > > turns everything into sizetype instead of [s]sizetype dependent on > > the Ada type "signedness")? > > What do you mean by "Ada turns everything into sizetype" here? AFAIK the Ada > compiler behaves like the other compilers, i.e. domain types are built with > > /* Create a type of integers to be the TYPE_DOMAIN of an ARRAY_TYPE. > MAXVAL should be the maximum value in the domain > (one less than the length of the array). > > The maximum value that MAXVAL can have is INT_MAX for a HOST_WIDE_INT. > We don't enforce this limit, that is up to caller (e.g. language front > end). > The limit exists because the result is a signed type and we don't handle > sizes that use more than one HOST_WIDE_INT. */ > > tree > build_index_type (tree maxval) > { > return build_range_type (sizetype, size_zero_node, maxval); > } > > so are all subtypes of sizetype (gigi has create_index_type instead because it > needs to have non-shared range types and lower bounds, but it's equivalent). Sure, but only Ada allows user specified index types (AFAIK). At least for the C family domains are always unsigned and fit in sizetype. The middle-end / stor-layout code should get a "proper" domain type from the frontends - either they canonicalize it to one that fits sizetype or they provide a different typed domain (not sure which one is best, but both are probably managable). Richard.
