[Bug tree-optimization/17217] New: not removing removal of nested structs

[Bug tree-optimization/17217] New: not removing removal of nested structs

[pinskia at gcc dot gnu dot org]

gcc -O3 and you will see that the load and store to the struct is still there for j.
int h(int *a);
int f(int i, int j)
{
  int t = i;
  int t1 = j;
  int g()
  {
     return h(&t) + t1;
  }
  return g() + t1;
}

I found this when looking at facerec which uses nested functions.

-- 
           Summary: not removing removal of nested structs
           Product: gcc
           Version: 3.5.0
            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=17217

[Bug tree-optimization/17217] not removing removal of nested structs

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-08-27 19:42 -------
Here is the unnested version:
int h(int *a);
struct G
{
int t;
int t1;
};
int g1(struct G*);
int f1(int i, int j)
{
  struct G nestedf1={i,j};
  return g1(&nestedf1)+nestedf1.t1;
}
static int g1(struct G *nestedf1)
{
  return h(&nestedf1->t)+ nestedf1->t1;
}

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17217

[Bug tree-optimization/17217] not removing removal of nested structs

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-08-27 22:13 -------
Daniel is this related to the aliasing stuff you are working on, I assume, if you get some time could you 
look to see if what you do actually fixes this?

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dberlin at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17217

[Bug tree-optimization/17217] not removing removal of nested structs

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-08-31 05:26 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2004-08-31 05:26:12
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17217

[Bug tree-optimization/17217] not removing removal of nested structs

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-16 17:37 -------
Fixed in 4.1.0 and above by Daniel's aliasing improvements.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17217

[Bug tree-optimization/17217] not removing removal of nested structs

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2008-09-16 01:03 -------
Actually the code to fix this was disabled as you can do pointer tricks to get
back to the original struct (well not in the nested case though).


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |
   Target Milestone|4.1.0                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17217

[Bug tree-optimization/17217] not removing removal of nested structs

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=17217

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|2005-01-25 03:37:17         |2021-09-03
     Ever confirmed|0                           |1

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So where is a better testcase (which is not depedent on how gimplifier works):
int h(int *a);
int f(int i, int j)
{
  int t = i;
  int t1 = j;
  int g()
  {
    int t11 = t1;
    int t2 = h(&t);
    return t2 + t11;
  }
  int t3 = g();
  return t3 + t1;
}

---- CUT ---
On the gimple level we get:
  _3 = __builtin_dwarf_cfa (0);
  FRAME.1.FRAME_BASE.PARENT = _3;
  FRAME.1.t = i_5(D);
  FRAME.1.t1 = j_7(D);
  t2_11 = h (&FRAME.1.t);
  _12 = j_7(D) + t2_11;
  _9 = FRAME.1.t1;
  _10 = _9 + _12;

We should know that FRAME.1 is special in that h can only escape t field of
FRAME.1 and not the other fields of FRAME.1 too.