https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93961
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |marxin at gcc dot gnu.org
--- Comment #5 from Martin Liška <marxin at gcc dot gnu.org> ---
commit r10-7125-ge835226bab5b3575c8a55c048dcfed3d4cde5e0e
Author: Eric Botcazou <[email protected]>
Date: Wed Mar 11 11:29:39 2020 +0100
Fix GIMPLE verification failure in LTO mode on Ada code
The issue is that tree_is_indexable doesn't return the same result for
a FIELD_DECL with QUAL_UNION_TYPE and the QUAL_UNION_TYPE, resulting
in two instances of the QUAL_UNION_TYPE in the bytecode. The result
for the type is the correct one (false, since it is variably modified)
while the result for the field is falsely true because:
else if (TREE_CODE (t) == FIELD_DECL
&& lto_variably_modified_type_p (DECL_CONTEXT (t)))
return false;
is not satisfied. The reason for this is that the DECL_QUALIFIER of
fields of a QUAL_UNION_TYPE depends on a discriminant in Ada, which
means that the size of the type does too (CONTAINS_PLACEHOLDER_P),
which in turn means that it is reset to a mere PLACEHOLDER_EXPR by
free_lang_data, which finally means that the size of DECL_CONTEXT is
too, so RETURN_TRUE_IF_VAR is false.
In other words, the CONTAINS_PLACEHOLDER_P property of the DECL_QUALIFIER
of fields of a QUAL_UNION_TYPE hides the variably_modified_type_p property
of these fields, if you look from the outside.
PR middle-end/93961
* tree.c (variably_modified_type_p) <RECORD_TYPE>: Recurse into
fields whose type is a qualified union.
