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Subject: [Bug tree-optimization/30708] [4.1 Regression] Aliasing miscompilation
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------- Comment #1 from rguenth at gcc dot gnu dot org  2007-02-05 14:19 -------
Confirmed.  Maybe related to PR30088.  The first alias dump at -O2 (-O
-fstrict-aliasing is fine) has

<bb 0>:
  #   common_head_5 = V_MUST_DEF <common_head_4>;
  common_head = 0B;

...

<L0>:;
  p_10 = &common_head;
  goto <bb 4> (<L3>);

<L1>:;
  #   VUSE <TMT.6_24>;
  D.1631_16 = sym_1->size;
  #   VUSE <HEAP.5_22>;
  D.1632_17 = *p_2;
...

  # p_2 = PHI <p_10(1), p_21(3)>;
<L3>:;
  #   VUSE <HEAP.5_22>;
  D.1632_11 = *p_2;
  if (D.1632_11 != 0B) goto <L1>; else goto <L4>;


so we have both HEAP.5 and common_head_5 used as tags for common_heap.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |alias, wrong-code
   Last reconfirmed|0000-00-00 00:00:00         |2007-02-05 14:19:20
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30708