[Bug tree-optimization/23838] New: infinite loop in dse

[Bug tree-optimization/23838] New: infinite loop in dse

[belyshev at depni dot sinp dot msu dot ru]

// testcase, compile with "-O2 -fno-tree-dce -fno-tree-ccp -fno-tree-copy-prop
-fno-tree-dominator-opts"

int foo (void);

struct A {
  struct B {
    struct B *n;
  } *p;
};

static inline void baz (struct A *a)
{
  a->p = a->p->n;
}

void bar (struct A a)
{
  while (foo ())
    baz (&a);
  while (foo ());
}

-- 
           Summary: infinite loop in dse
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Keywords: compile-time-hog
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: belyshev at depni dot sinp dot msu dot ru
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23838

[Bug tree-optimization/23838] infinite loop in dse

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-12 19:45 -------
Confirmed.
The loop below:
      /* Skip through any PHI nodes we have already seen if the PHI
	 represents the only use of this store.

	 Note this does not handle the case where the store has
	 multiple V_{MAY,MUST}_DEFs which all reach a set of PHI nodes in the
	 same block.  */

Is causing the issue.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |law at gcc dot gnu dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-09-12 19:46:00
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23838