Am Montag, dem 17.06.2024 um 14:57 +0200 schrieb Jakub Jelinek: > On Mon, Jun 17, 2024 at 02:42:05PM +0200, Richard Biener wrote: > > > > > I am trying to understand what check_qualified_type > > > > > does exactly. The direct comparison of TYPE_NAMES seems incorrect > > > > > for C and its use is c_update_type_canonical then causes > > > > > PR114930 and PR115502. In the later function I think > > > > > it is not really needed and I guess one could simply remove > > > > > it, but I wonder if it works incorrectly in other cases > > > > > too? > > > > > > > > TYPE_NAMES is compared because IIRC typedefs are recorded as variants > > > > and 'const T' isn't the same as 'const int' with typedef int T. > > > > > > so if it is intentional that it differentiates between > > > > > > struct foo > > > > > > and > > > > > > typedef struct foo bar > > > > > > then I will change c_update_type_canonical to not use it, > > > because both types should have the same TYPE_CANONICAL > > > > The check is supposed to differentiate between variants and all variants > > have the same TYPE_CANONICAL so I'm not sure why you considered using > > this function for canonical type compute? > > I've done that and that was because build_qualified_type uses that > predicate, where qualified types created by build_qualified_type have > as TYPE_CANONICAL the qualified type of the main variant of the canonical > type, while in all other cases TYPE_CANONICAL is just the main variant of > the type. > Guess we could also just do > if (TYPE_QUALS (x) == TYPE_QUALS (t)) > TYPE_CANONICAL (x) = TYPE_CANONICAL (t); > else if (TYPE_CANONICAL (t) != t > || TYPE_QUALS (x) != TYPE_QUALS (TYPE_CANONICAL (t))) > TYPE_CANONICAL (x) > = build_qualified_type (TYPE_CANONICAL (t), TYPE_QUALS (x)); > else > TYPE_CANONICAL (x) = x; >
Ok, that works. I think the final "else" is then then impossible to reach and can be eliminated as well, because if TYPE_CANONICAL (t) == t then TYPE_QUALS (x) == TYPE_QUALS (TYPE_CANONICAL (t)) is identical to TYPE_QUALS (x) == TYPE_QUALS (t) which is the first case. Martin
