https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106833
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Kewen Lin from comment #1)
> IMHO this is an omission when we were adding supports for opaque type, const
> __vector_quad and __vector_quad should be taken as
> canonical_types_compatible.
>
> I wonder if we can simply take it just like what it handles for
> "Non-aggregate types", for example:
>
> diff --git a/gcc/tree.cc b/gcc/tree.cc
> index 2f488e4467c..555e96c59d5 100644
> --- a/gcc/tree.cc
> +++ b/gcc/tree.cc
> @@ -13510,6 +13510,7 @@ gimple_canonical_types_compatible_p (const_tree t1,
> const_tree t2,
> || TREE_CODE (t1) == VECTOR_TYPE
> || TREE_CODE (t1) == COMPLEX_TYPE
> || TREE_CODE (t1) == OFFSET_TYPE
> + || TREE_CODE (t1) == OPAQUE_TYPE
> || POINTER_TYPE_P (t1))
> {
> /* Can't be the same type if they have different recision. */
>
> Or adding one default hook which does the similar thing, and then if one
> target needs some target specific checks on its opaque type, one specific
> hook can be provided.
I'm quoting tree.def, emphasis mine:
/* This is for types that will use MODE_OPAQUE in the back end. They are meant
to be able to go in a register of some sort but are _EXPLICITLY NOT TO BE
CONVERTED_ or operated on like INTEGER_TYPE. They will have size and
alignment information only. */
DEFTREECODE (OPAQUE_TYPE, "opaque_type", tcc_type, 0)
so why should we care about special-casing them? The target should have set
TYPE_CANONICAL appropriately if necessary, why didn't it? Btw, 'const'
qualification should go into the type variant chain (well, for "normal"
types), where TYPE_MAIN_VARIANT is the unqualified type variant.
TYPE_CANONICAL
shouldn't come into play here.
Btw, the whole idea of "opaque" is a hack and it seems to backfire now?
