[Bug c/114493] [11/12/13/14/15 Regression] internal compiler error: in fld_incomplete_type_of with may_alias
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114493 --- Comment #12 from GCC Commits --- The releases/gcc-14 branch has been updated by Jakub Jelinek : https://gcc.gnu.org/g:56c73729c3eab08ca48f366bd435f98457743e45 commit r14-10286-g56c73729c3eab08ca48f366bd435f98457743e45 Author: Jakub Jelinek Date: Thu Jun 6 22:12:11 2024 +0200 c: Fix up pointer types to may_alias structures [PR114493] The following testcase ICEs in ipa-free-lang, because the fld_incomplete_type_of gcc_assert (TYPE_CANONICAL (t2) != t2 && TYPE_CANONICAL (t2) == TYPE_CANONICAL (TREE_TYPE (t))); assertion doesn't hold. This is because t is a struct S * type which was created while struct S was still incomplete and without the may_alias attribute (and TYPE_CANONICAL of a pointer type is a type created with can_alias_all = false argument), while later on on the struct definition may_alias attribute was used. fld_incomplete_type_of then creates an incomplete distinct copy of the structure (but with the original attributes) but pointers created for it are because of the "may_alias" attribute TYPE_REF_CAN_ALIAS_ALL, including their TYPE_CANONICAL, because while that is created with !can_alias_all argument, we later set it because of the "may_alias" attribute on the to_type. This doesn't ICE with C++ since PR70512 fix because the C++ FE sets TYPE_REF_CAN_ALIAS_ALL on all pointer types to the class type (and its variants) when the may_alias is added. The following patch does that in the C FE as well. 2024-06-06 Jakub Jelinek PR c/114493 * c-decl.cc (c_fixup_may_alias): New function. (finish_struct): Call it if "may_alias" attribute is specified. * gcc.dg/pr114493-1.c: New test. * gcc.dg/pr114493-2.c: New test. (cherry picked from commit d5a3c6d43acb8b2211d9fb59d59482d74c010f01)
[Bug c/114493] [11/12/13/14/15 Regression] internal compiler error: in fld_incomplete_type_of with may_alias
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114493 --- Comment #11 from GCC Commits --- The master branch has been updated by Jakub Jelinek : https://gcc.gnu.org/g:d5a3c6d43acb8b2211d9fb59d59482d74c010f01 commit r15-1080-gd5a3c6d43acb8b2211d9fb59d59482d74c010f01 Author: Jakub Jelinek Date: Thu Jun 6 22:12:11 2024 +0200 c: Fix up pointer types to may_alias structures [PR114493] The following testcase ICEs in ipa-free-lang, because the fld_incomplete_type_of gcc_assert (TYPE_CANONICAL (t2) != t2 && TYPE_CANONICAL (t2) == TYPE_CANONICAL (TREE_TYPE (t))); assertion doesn't hold. This is because t is a struct S * type which was created while struct S was still incomplete and without the may_alias attribute (and TYPE_CANONICAL of a pointer type is a type created with can_alias_all = false argument), while later on on the struct definition may_alias attribute was used. fld_incomplete_type_of then creates an incomplete distinct copy of the structure (but with the original attributes) but pointers created for it are because of the "may_alias" attribute TYPE_REF_CAN_ALIAS_ALL, including their TYPE_CANONICAL, because while that is created with !can_alias_all argument, we later set it because of the "may_alias" attribute on the to_type. This doesn't ICE with C++ since PR70512 fix because the C++ FE sets TYPE_REF_CAN_ALIAS_ALL on all pointer types to the class type (and its variants) when the may_alias is added. The following patch does that in the C FE as well. 2024-06-06 Jakub Jelinek PR c/114493 * c-decl.cc (c_fixup_may_alias): New function. (finish_struct): Call it if "may_alias" attribute is specified. * gcc.dg/pr114493-1.c: New test. * gcc.dg/pr114493-2.c: New test.
[Bug c/114493] [11/12/13/14/15 Regression] internal compiler error: in fld_incomplete_type_of with may_alias
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114493 --- Comment #10 from Jakub Jelinek --- Created attachment 58337 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58337=edit gcc15-pr114493.patch Untested fix.
[Bug c/114493] [11/12/13/14/15 Regression] internal compiler error: in fld_incomplete_type_of with may_alias
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114493 --- Comment #9 from Jakub Jelinek --- That was added for C++ in PR70512.
[Bug c/114493] [11/12/13/14/15 Regression] internal compiler error: in fld_incomplete_type_of with may_alias
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114493
Jakub Jelinek changed:
What|Removed |Added
CC||jakub at gcc dot gnu.org
--- Comment #8 from Jakub Jelinek ---
This doesn't ICE in C++, because the C++ FE forcibly updates the corresponding
pointer types in:
#0 fixup_may_alias (klass=) at
../../gcc/cp/class.cc:2328
#1 0x00456835 in fixup_attribute_variants (t=) at ../../gcc/cp/class.cc:2354
#2 0x006f3024 in cp_parser_class_head (parser=0x7fffea2dea80,
nested_name_specifier_p=0x7fffd5ff) at ../../gcc/cp/parser.cc:27831
/* KLASS is a class that we're applying may_alias to after the body is
parsed. Fixup any POINTER_TO and REFERENCE_TO types. The
canonical type(s) will be implicitly updated. */
static void
fixup_may_alias (tree klass)
{
tree t, v;
for (t = TYPE_POINTER_TO (klass); t; t = TYPE_NEXT_PTR_TO (t))
for (v = TYPE_MAIN_VARIANT (t); v; v = TYPE_NEXT_VARIANT (v))
TYPE_REF_CAN_ALIAS_ALL (v) = true;
for (t = TYPE_REFERENCE_TO (klass); t; t = TYPE_NEXT_REF_TO (t))
for (v = TYPE_MAIN_VARIANT (t); v; v = TYPE_NEXT_VARIANT (v))
TYPE_REF_CAN_ALIAS_ALL (v) = true;
}
Now, fixup_attribute_variants also does:
for (variants = TYPE_NEXT_VARIANT (t);
variants;
variants = TYPE_NEXT_VARIANT (variants))
{
/* These are the two fields that check_qualified_type looks at and
are affected by attributes. */
TYPE_ATTRIBUTES (variants) = attrs;
unsigned valign = align;
if (TYPE_USER_ALIGN (variants))
valign = MAX (valign, TYPE_ALIGN (variants));
else
TYPE_USER_ALIGN (variants) = user_align;
SET_TYPE_ALIGN (variants, valign);
TYPE_PACKED (variants) = packed;
if (may_alias)
fixup_may_alias (variants);
}
I think the TYPE_ATTRIBUTES update isn't needed, because
decl_attributes (, attributes, (int) ATTR_FLAG_TYPE_IN_PLACE);
should update the variants already:
984 TYPE_ATTRIBUTES (*anode) = r;
985 /* If this is the main variant, also push the
attributes
986 out to the other variants. */
987 if (*anode == TYPE_MAIN_VARIANT (*anode))
988 {
989 for (tree variant = *anode; variant;
990variant = TYPE_NEXT_VARIANT (variant))
991 {
992 if (TYPE_ATTRIBUTES (variant) == old_attrs)
993 TYPE_ATTRIBUTES (variant)
994 = TYPE_ATTRIBUTES (*anode);
995 else if (!find_same_attribute
996(attr, TYPE_ATTRIBUTES (variant)))
997 TYPE_ATTRIBUTES (variant) = tree_cons
998 (name, args, TYPE_ATTRIBUTES (variant));
999 }
1000}
Seems finish_struct doesn't actually call layout_type on the type variants,
wonder what does that, but I'd think that stuff like TYPE_USER_ALIGN,
TYPE_ALIGN would be finalized when layout_type is performed for those.
TYPE_PACKED is apparently done in
finish_record_layout even for the variants (called from layout_type).
[Bug c/114493] [11/12/13/14/15 Regression] internal compiler error: in fld_incomplete_type_of with may_alias
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114493 Sam James changed: What|Removed |Added CC||fw at gcc dot gnu.org --- Comment #7 from Sam James --- I've been scratching my head as to why matoro and someone else reported it with Samba today out of nowhere. I assume it's because of https://sourceware.org/git/?p=glibc.git;a=commit;h=26e7005728f0eea2972474e6be2905c467661237. I think it was suggested that a forward decl might work to mitigate the ICE but I haven't tried (yet).
