[Bug tree-optimization/16538] New: Missed jump threading opportunity with struct fields (but RTL thread_jumps does catch it)

[Bug tree-optimization/16538] New: Missed jump threading opportunity with struct fields (but RTL thread_jumps does catch it)

[steven at gcc dot gnu dot org]

We are missing a few jump threading opportunities
of the following form in SPEC and in GCC itself:

------------------------------------------------
struct foo
{
  int field1;
  int field2;
};

struct foo glob;

void
bar (void)
{
  struct foo *g1, *g2;
  g1 = g2 = &glob;
  int i;

  if (!g1->field1)
    g1->field2 = g1->field1;

  if (!g2->field1)
    g2->field2 = g2->field1;
}
------------------------------------------------


The .optimized dump looks like this:

;; Function bar (bar)

bar ()
{
  int i;
  struct foo * g2;
  struct foo * g1;
  int T.1;
  int T.0;

<bb 0>:
  if (glob.field1 == 0) goto <L0>; else goto <L1>;

<L0>:;
  glob.field2 = 0;

<L1>:;
  if (glob.field1 == 0) goto <L2>; else goto <L3>;

<L2>:;
  glob.field2 = 0;

<L3>:;
  return;

}


We eventually end up threading this jump on RTL.

-- 
           Summary: Missed jump threading opportunity with struct fields
                    (but RTL thread_jumps does catch it)
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: steven at gcc dot gnu dot org
                CC: dnovillo at redhat dot com,gcc-bugs at gcc dot gnu dot
                    org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16538

[Bug tree-optimization/16538] Missed jump threading opportunity with struct fields (but RTL thread_jumps does catch it)

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-07-14 15:28 -------
Confirmed, this is basically PR 13761 really.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |13761
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |alias, TREE
   Last reconfirmed|0000-00-00 00:00:00         |2004-07-14 15:28:58
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16538

[Bug tree-optimization/16538] Missed jump threading opportunity with struct fields (but RTL thread_jumps does catch it)

[law at redhat dot com]

------- Additional Comments From law at redhat dot com  2005-02-14 20:06 -------
This is not a jump threading issue.  This is an aliasing issue.  If the aliasing
code is fixed, then the new jump thread selection code will handle this correctly.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16538

[Bug tree-optimization/16538] Missed jump threading opportunity with struct fields (but RTL thread_jumps does catch it)

[law at redhat dot com]

------- Additional Comments From law at redhat dot com  2005-04-23 00:57 -------
This appears to be fixed now (probably the combination of Dan's aliasing
work and the jump threading changes).

Can a bugmaster please close this :-)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16538

[Bug tree-optimization/16538] Missed jump threading opportunity with struct fields (but RTL thread_jumps does catch it)

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2005-04-23 16:47 -------
This was fixed by just Dan's alias patches. 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16538

[Bug tree-optimization/16538] Missed jump threading opportunity with struct fields (but RTL thread_jumps does catch it)

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16538

[Bug tree-optimization/16538] Missed jump threading opportunity with struct fields (but RTL thread_jumps does catch it)

[steven at gcc dot gnu dot org]

-- 
Bug 16538 depends on bug 13761, which changed state.

Bug 13761 Summary: [tree-ssa] component refs to the same struct should not alias
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13761

           What    |Old Value                   |New Value
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16538

[Bug tree-optimization/16538] Missed jump threading opportunity with struct fields (but RTL thread_jumps does catch it)

[steven at gcc dot gnu dot org]

-- 
Bug 16538 depends on bug 13761, which changed state.

Bug 13761 Summary: [tree-ssa] component refs to the same struct should not alias
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13761

           What    |Old Value                   |New Value
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16538