[Bug optimization/14706] New: [tree-ssa] range checks should be merged.

[Bug optimization/14706] New: [tree-ssa] range checks should be merged.

[kazu at cs dot umass dot edu]

We know that fold() can fold (a > 10 && a < 20) into
((unsigned int) (a - 11) <= 8).

We should also be able to optimize foo() in a similar way.
Note that bar() can be implemented using a conditional move and no jump.

int g;

void
foo (int a)
{
  if (a > 10)
    if (a < 20)
      g = 0;
}

void
bar (int a)
{
  if ((unsigned int) (a - 11) <= 8)
    g = 0;
}

-- 
           Summary: [tree-ssa] range checks should be merged.
           Product: gcc
           Version: tree-ssa
            Status: UNCONFIRMED
          Keywords: pessimizes-code
          Severity: enhancement
          Priority: P2
         Component: optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kazu at cs dot umass dot edu
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14706

[Bug optimization/14706] [tree-ssa] range checks should be merged.

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-03-24 05:31 -------
Confirmed, this should only happen right before converting to RTL as it will prevent other optimizations 
from happening.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2004-03-24 05:31:10
               date|                            |
   Target Milestone|---                         |tree-ssa


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14706

[Bug optimization/14706] [tree-ssa] range checks should be merged.

[kazu at cs dot umass dot edu]

------- Additional Comments From kazu at cs dot umass dot edu  2004-04-04 16:29 -------
Speaking of "should only happen right before ...", we may want to
disable the range merging code in fold() because that tends to create
temporaries (after we have the ability to merge ranges in tree-ssa).
AFAIK, the more temporaries we have, the more memory usage, the fewer
jump threading opportunities, etc.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14706

[Bug tree-optimization/14706] [tree-ssa] range checks should be merged.

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|3.5.0                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14706