------- Comment #5 from rguenth at gcc dot gnu dot org 2010-02-11 13:31 -------
The basic issue here is that sub0 is inlined into main and we assign different
alias sets to struct my_c_type_1 and struct c_type_1 because they have
different
tags. Something ok for C but too strict for cross-language TBAA.
Thus tree DSE removes the initialization of c_type.j.
main (<unnamed-signed:32> argc, <unnamed-signed:8> * * argv)
{
<unnamed-signed:32> D.2072;
struct my_c_type_1 & restrict my_type;
struct c_type_1 c_type;
<unnamed-signed:32> D.2054;
<bb 2>:
c_type.j = 11;
my_type_5 = (struct my_c_type_1 & restrict) &c_type;
D.2072_6 = my_type_5->j;
if (D.2072_6 != 11)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
_gfortran_abort ();
<bb 4>:
return 0;
tree DCE doesn't because its aliased.
The offending check in gimple_types_compatible that forces us to not
merge the two structure types is
/* The struct tags shall compare equal. */
if (!compare_type_names_p (TYPE_MAIN_VARIANT (t1),
TYPE_MAIN_VARIANT (t2), false))
goto different_types;
This bug will only be fully fixed with the introduction of a purely
structural type hierarchy for TBAA. We can use TYPE_CANONICAL for that
once we make that unnecessary in its current meaning (meaning doing
the gimple type-merging per TU at gimplification time).
For now we can relax the alias-oracle somewhat to give leeway to this
and similar (even if slightly undefined) testcases.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
Last reconfirmed|2009-10-10 18:43:53 |2010-02-11 13:31:59
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41664
