[Bug c++/36369] [4.3/4.4 Regression] may_alias broken with previous uses of non attributed type in some cases

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

------- Comment #3 from pinskia at gcc dot gnu dot org  2008-05-29 13:48 -------
For my testcase with the C front-end:
;; *y = *(const long_a *) &x->a
(insn 7 6 8 t.cc:12 (set (reg:SI 61)
        (mem:SI (reg/v/f:SI 59 [ x ]) [0 S4 A32])) -1 (nil))

While with the C++ front-end:
;; *y = *(const long_a *) &x->a
(insn 7 6 8 t.cc:12 (set (reg:SI 61)
        (mem:SI (reg/v/f:SI 59 [ x ]) [3 S4 A32])) -1 (nil))

I think the issue here is really the canonical type is set for C++ front-end
which is wrong for may_alias types.

This is wrong code and not just a warning as shown by the rtl expansion.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |critical
           Keywords|                            |wrong-code
            Summary|[4.3/4.4 Regression] Type   |[4.3/4.4 Regression]
                   |punning warning with        |may_alias broken with
                   |may_alias attribute depends |previous uses of non
                   |on unrelated class          |attributed type in some
                   |definition                  |cases


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36369