[Bug c++/47541] [4.5/4.6 Regression] For integer pointers, the value of ++*p is not written back to memory

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47541

--- Comment #8 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-31 16:28:19 UTC ---
Hmm.  We have

  D.10321_19 = MEM[(const struct RefCount &)ptr_3(D) + 8].count_;
  MEM[(struct RefCount *)D.9717_8 + 8B].count_ = D.10321_19;
  D.10322_20 = MEM[(struct RefCount *)D.9717_8 + 8B].count_;
...
  MEM[(int *)D.10322_20] = D.10324_22;

so _19 isn't used at this point (as in, dereferenced) directly.

Constraints:

PARM_NOALIAS.204.64+64 = NONLOCAL
PARM_NOALIAS.204.128+64 = NONLOCAL
ptr = &PARM_NOALIAS.204.64+64
D.10321_19 = *ptr + 128
*D.9717_8 + 128 = D.10321_19
D.10322_20 = *D.9717_8 + 128
D.10323_21 = *D.10322_20

Note the funny fact that no constraint is there for
the subvar starting at 0.  And we end up with

  # PT = nonlocal escaped
  D.10320_18 = MEM[(const struct RefCount &)ptr_3(D) + 8].ptr_;
  MEM[(struct RefCount *)D.9717_8 + 8B].ptr_ = D.10320_18;
  # PT =
  D.10321_19 = MEM[(const struct RefCount &)ptr_3(D) + 8].count_;
  MEM[(struct RefCount *)D.9717_8 + 8B].count_ = D.10321_19;
  # PT = nonlocal escaped
  D.10322_20 = MEM[(struct RefCount *)D.9717_8 + 8B].count_;

which means that we think we access PARM_NOALIAS.204.196+64 when
loading from count_.  This looks like a type issue to me, related to
pass-by-reference + restrict handling.  Eventually related to
how inheritance is represented.