On Tue, 28 Feb 2023, Jakub Jelinek wrote:
> On Tue, Feb 28, 2023 at 09:43:37AM +0000, Richard Biener wrote:
> > We try to make sure to put all built types into the type merging
> > machinery, so I think it shouldn't happen - but then I cannot rule
> > it out. I'm also not sure whether duplicates would really pose
> > a problem here (other than waste). If we want to make sure we should
> > probably enhance verify_types to verify the TYPE_POINTER_TO chain ...
> >
> > > I'll try to debug why those user aligned types become TYPE_MAIN_VARIANT
> > > though...
>
> Ok, so this happens already in the FEs when trying to add the attribute:
> #0 build_distinct_type_copy (type=<pointer_type 0x7fffea0219d8>) at
> ../../gcc/tree.cc:5735
> #1 0x0000000000c2327b in build_type_attribute_qual_variant
> (otype=<pointer_type 0x7fffea0219d8>, attribute=<tree_list 0x7fffea01e938>,
> quals=0) at ../../gcc/attribs.cc:1298
> #2 0x0000000000c245b0 in build_type_attribute_variant (ttype=<pointer_type
> 0x7fffea0219d8>, attribute=<tree_list 0x7fffea01e938>) at
> ../../gcc/attribs.cc:1591
> #3 0x0000000000c22325 in decl_attributes (node=0x7fffffffd008,
> attributes=<tree_list 0x7fffea01e910>, flags=1, last_decl=<tree 0x0>) at
> ../../gcc/attribs.cc:964
>
> So, perhaps the !TYPE_QUALS (t) could be just an assert, but maybe next to
> the !TYPE_USER_ALIGN (t) (or just instead of?) we need !TYPE_ATTRIBUTES (t).
> Because addition of attributes (but anything else that causes
> build_distinct_type_copy rather than build_variant_type_copy) will create
> new TYPE_MAIN_VARIANTS.
> Looking around, TYPE_REF_IS_RVALUE references also create distinct types,
> and while the C++ FE sticks them into the TYPE_REFERENCE_TO chain, it
> ensures they go after the corresponding !TYPE_REF_IS_RVALUE entry, so
> perhaps LTO should !TYPE_REF_IS_RVALUE for REFERENCE_TYPEs.
> Other uses of build_distinct_type_copy in the FEs are mostly related to
> ARRAY_TYPEs (in C FE as well as c-common). Asan uses it solely on integral
> types, etc. For attributes, big question is if it when we set
> *no_addr_attrs = true we still tweak some things on the type (not in place)
> or not.
>
> So, here are two possible variant patches which fix the ICE on the
> testcase too.
>
> 2023-02-28 Jakub Jelinek <ja...@redhat.com>
>
> PR target/108910
> * lto-common.cc (lto_fixup_prevailing_type): Don't add t to
> TYPE_POINTER_TO or TYPE_REFERENCE_TO chain if it has
> TYPE_ATTRIBUTES, or is TYPE_REF_IS_RVALUE, or some other type
> with the same TYPE_MODE and TYPE_REF_CAN_ALIAS_ALL flag is already
> present.
>
> --- gcc/lto/lto-common.cc.jj 2023-01-16 11:52:16.165732856 +0100
> +++ gcc/lto/lto-common.cc 2023-02-28 12:30:37.014471255 +0100
> @@ -984,21 +984,36 @@ lto_fixup_prevailing_type (tree t)
> TYPE_NEXT_VARIANT (t) = TYPE_NEXT_VARIANT (mv);
> TYPE_NEXT_VARIANT (mv) = t;
> }
> -
> - /* The following reconstructs the pointer chains
> - of the new pointed-to type if we are a main variant. We do
> - not stream those so they are broken before fixup. */
> - if (TREE_CODE (t) == POINTER_TYPE
> - && TYPE_MAIN_VARIANT (t) == t)
> - {
> - TYPE_NEXT_PTR_TO (t) = TYPE_POINTER_TO (TREE_TYPE (t));
> - TYPE_POINTER_TO (TREE_TYPE (t)) = t;
> - }
> - else if (TREE_CODE (t) == REFERENCE_TYPE
> - && TYPE_MAIN_VARIANT (t) == t)
> + else if (!TYPE_ATTRIBUTES (t))
> {
> - TYPE_NEXT_REF_TO (t) = TYPE_REFERENCE_TO (TREE_TYPE (t));
> - TYPE_REFERENCE_TO (TREE_TYPE (t)) = t;
> + /* The following reconstructs the pointer chains
> + of the new pointed-to type if we are a main variant. We do
> + not stream those so they are broken before fixup.
> + Don't add it if despite being main variant it has
> + attributes (then it was created with build_distinct_type_copy).
> + Similarly don't add TYPE_REF_IS_RVALUE REFERENCE_TYPEs.
> + Don't add it if there is something in the chain already. */
> + tree *p = NULL;
> + if (TREE_CODE (t) == POINTER_TYPE)
> + p = &TYPE_POINTER_TO (TREE_TYPE (t));
> + else if (TREE_CODE (t) == REFERENCE_TYPE && !TYPE_REF_IS_RVALUE (t))
> + p = &TYPE_REFERENCE_TO (TREE_TYPE (t));
> + if (p)
> + {
> + tree t2;
> + for (t2 = *p; t2; t2 = TYPE_NEXT_PTR_TO (t2))
> + if (TYPE_MODE (t2) == TYPE_MODE (t)
> + && TYPE_REF_CAN_ALIAS_ALL (t2) == TYPE_REF_CAN_ALIAS_ALL (t))
> + break;
Can we elide this searching please? Having duplicated should be harmless
unless proved otherwise.
OK with that change.
Richard.
> + if (t2 == NULL_TREE)
> + {
> + if (TREE_CODE (t) == POINTER_TYPE)
> + TYPE_NEXT_PTR_TO (t) = *p;
> + else
> + TYPE_NEXT_REF_TO (t) = *p;
> + *p = t;
> + }
> + }
> }
> }
>
>
>
> Jakub
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
HRB 36809 (AG Nuernberg)
