[Bug tree-optimization/32328] [4.2 Regression] -fstrict-aliasing causes skipped code

[rguenth at gcc dot gnu dot org]

------- Comment #9 from rguenth at gcc dot gnu dot org  2007-06-20 15:12 -------
Confirmed.

struct barstruct { char const* some_string; };

void changethepointer(struct barstruct**);

void baz()
{
        struct barstruct bar1;
        struct barstruct* barptr = &bar1;
        changethepointer(&barptr);
        barptr->some_string = "Everything's OK!";
}


We end up with

baz ()
{
  struct barstruct * barptr;
  struct barstruct bar1;
  struct barstruct * barptr.0;

<bb 2>:
  #   barptr_2 = V_MUST_DEF <barptr_1>;
  barptr = &bar1;
  #   barptr_6 = V_MAY_DEF <barptr_2>;
  #   SFT.1_7 = V_MAY_DEF <SFT.1_4>;
  #   NONLOCAL.7_8 = V_MAY_DEF <NONLOCAL.7_5>;
  changethepointer (&barptr);
  #   VUSE <barptr_6>;
  barptr.0_3 = barptr;
  #   SFT.1_9 = V_MAY_DEF <SFT.1_7>;
  barptr.0_3->some_string = &"Everything\'s OK!"[0];
  return;

}

because of a wrong points-to set again:

barptr.0_3 = { bar1 }

The constraints are

Constraints: 

ANYTHING = &ANYTHING
READONLY = &ANYTHING
INTEGER = &ANYTHING
ESCAPED_VARS = *ESCAPED_VARS
NONLOCAL.7 = ESCAPED_VARS
ESCAPED_VARS = &NONLOCAL.7
ESCAPED_VARS = &NONLOCAL.7
barptr = &bar1
ESCAPED_VARS = &bar1
ESCAPED_VARS = &barptr
barptr.0_3 = barptr

where ESCAPED_VARS = &barptr looks wrong?  I'd say it needs to be
ESCAPED_VARS = barptr instead.

Danny?


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dberlin at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-06-20 15:12:52
               date|                            |
            Summary|4.2.0: -O2 causes skipped   |[4.2 Regression] -fstrict-
                   |code                        |aliasing causes skipped code


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32328