[Bug tree-optimization/23134] New: Address escapes even though the called function does not cause it to escape

[Bug tree-optimization/23134] New: Address escapes even though the called function does not cause it to escape

[pinskia at gcc dot gnu dot org]

Take this "stupid" example (even though this most likely shows up in GCC but I don't know for sure):
int g1(int);
static void h(int *a) { *a = 1; }

int g(void)
{
  int t = 0;
  h(&t);
  int t1 = t;
  g1(t1);
  return t1 == t;
}

That return should have been turned into "return 1" as t does not escape via h as h only touches it.
Compile with -O3 -fno-inline to see the problem.

-- 
           Summary: Address escapes even though the called function does not
                    cause it to escape
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23134

[Bug tree-optimization/23134] Address escapes even though the called function does not cause it to escape

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |alias


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23134

[Bug tree-optimization/23134] Address escapes even though the called function does not cause it to escape

[belyshev at depni dot sinp dot msu dot ru]

------- Additional Comments From belyshev at depni dot sinp dot msu dot ru  2005-07-29 13:57 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-07-29 13:57:51
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23134

[Bug tree-optimization/23134] Address escapes even though the called function does not cause it to escape

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-11 17:20 -------
I think the FIXME in tree-ssa-operands.c is the issue here:
  /* FIXME - if we have better information from the static vars
     analysis, we need to make the cache call site specific.  This way
     we can have the performance benefits even if we are doing good
     optimization.  */

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23134