------- Additional Comments From nathan at codesourcery dot com 2005-09-27
10:51 -------
Subject: Re: [4.1 Regression] Ada bootstrap ICE in
build_int_cst_wide, at tree.c:795
ebotcazou at gcc dot gnu dot org wrote:
> In build_int_cst_wide, we're asserting that the type of shared constants
> attached to a type is precisely that type:
>
> t = TREE_VEC_ELT (TYPE_CACHED_VALUES (type), ix);
> if (t)
> {
> /* Make sure no one is clobbering the shared constant. */
> gcc_assert (TREE_TYPE (t) == type);
>
> But in set_sizetype we're boldly copying TYPE_CACHED_VALUES between types:
>
> /* We do want to use bitsizetype's cache, as we will be replacing that
> type. */
> TYPE_CACHED_VALUES (t) = TYPE_CACHED_VALUES (bitsizetype);
> TYPE_CACHED_VALUES_P (t) = TYPE_CACHED_VALUES_P (bitsizetype);
>
>
> Nathan, who is right here?
Both are correct. However it looks like some integer constant created before
set_sizetype is called has not got its type updated correctly.
The problem here is that we have to create some types before setting size_type,
and in creating those types we need to set their size to some integral
constant,
and that integral constant has to have a type. That uses the stub sizetype
type, which we overwrite further down set_sizetype.
/* Replace our original stub sizetype. */
memcpy (sizetype, t, tree_size (sizetype));
TYPE_MAIN_VARIANT (sizetype) = sizetype;
My guess is that we've already created some type variants of the stub type at
that point, which is not what I expected. There should really be an
gcc_assert (!TYPE_NEXT_VARIANT (sizetype) && !TYPE_NEXT_VARIANT (t));
just before the memcpy
nathan
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24053
