[Bug lto/41767] assertion in tree-sra.c

["jamborm at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #6 from jamborm at gcc dot gnu dot org  2009-10-27 13:59 -------
The problem here is that build_ref_for_offset_1() cannot find a field
corresponding to a replacement within its own aggregate.  The field is
identified by its offset (zero) and type.  Unfortunately,
types_compatible_p() claims that the type of the replacement (taken
from the expression where it occurs) and the field at the offset are
not compatible.  I have added some dumps to the beginning of the
function and got:

----------------------------------------------------------------------
picked field value

Determining compatibility of types:

Expected type (type of the scalar replacement):
 <pointer_type 0xb7726514
    type <union_type 0xb772612c tree_node SI
        size <integer_cst 0xb7687498 constant 32>
        unit size <integer_cst 0xb7687284 constant 4>
        align 32 symtab 0 alias set -1 canonical type 0xb772612c
        fields <field_decl 0xb76eee60 common type <record_type 0xb7720b54
tree_common>
            SI file b.h line 8 col 20 size <integer_cst 0xb7687498 32> unit
size <integer_cst 0xb7687284 4>
            align 32 offset_align 128
            offset <integer_cst 0xb76872a0 constant 0>
            bit offset <integer_cst 0xb7687700 constant 0> context <union_type
0xb772612c tree_node> chain <field_decl 0xb76eef18 constructor>>
        pointer_to_this <pointer_type 0xb7726514>>
    unsigned SI size <integer_cst 0xb7687498 32> unit size <integer_cst
0xb7687284 4>
    align 32 symtab 0 alias set 4 canonical type 0xb7726514>


Record field type:
 <pointer_type 0xb7720e10
    type <union_type 0xb7720af0 tree_node SI
        size <integer_cst 0xb7687498 constant 32>
        unit size <integer_cst 0xb7687284 constant 4>
        align 32 symtab 0 alias set -1 canonical type 0xb7720af0
        fields <field_decl 0xb76eebdc common type <record_type 0xb7720b54
tree_common>
            SI file b.h line 8 col 20 size <integer_cst 0xb7687498 32> unit
size <integer_cst 0xb7687284 4>
            align 32 offset_align 128
            offset <integer_cst 0xb76872a0 constant 0>
            bit offset <integer_cst 0xb7687700 constant 0> context <union_type
0xb7720af0 tree_node> chain <field_decl 0xb76eec94 constructor>>
        pointer_to_this <pointer_type 0xb7720e10>>
    unsigned SI size <integer_cst 0xb7687498 32> unit size <integer_cst
0xb7687284 4>
    align 32 symtab 0 alias set 3 canonical type 0xb7720e10>


NOT compatible.

----------------------------------------------------------------------

I could workaround this and check whether all replacements can be
located within their aggregates before creating them but that does not
sound right.  Instead I think that the bug is either somewhere in type
merging or in types_compatible_p().


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41767