------- 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
