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* [Bug tree-optimization/21596] New: [4.0/4.1 Regression] extra temporaries when using global register variables
@ 2005-05-15 23:45 rth at gcc dot gnu dot org
  2005-05-15 23:57 ` [Bug tree-optimization/21596] " pinskia at gcc dot gnu dot org
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: rth at gcc dot gnu dot org @ 2005-05-15 23:45 UTC (permalink / raw)
  To: gcc-bugs

register int *reg __asm__("%edi");
int test () { return *--reg <= 0; }

With -O2 -fomit-frame-pointer, 4.0,

        movl    %edi, %eax
        leal    -4(%edi), %edi
        movl    -4(%eax), %eax
        testl   %eax, %eax

With 3.4,

        subl    $4, %edi
        cmpl    $0, (%edi)

The problem appears to begin at the tree level, with extra temporaries:

  reg.0 = reg;
  reg.2 = reg.0 - 4B;
  reg = reg.2;
  return *reg.2 <= 0;

We do consider hard register variables not is_gimple_reg, due to needing
to V_MAY_DEF them at call sites.  It would be nice if we could eliminate
these temporaries during TER, or something.

-- 
           Summary: [4.0/4.1 Regression] extra temporaries when using global
                    register variables
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rth at gcc dot gnu dot org
                CC: amacleod at redhat dot com,gcc-bugs at gcc dot gnu dot
                    org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21596


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [Bug tree-optimization/21596] [4.0/4.1 Regression] extra temporaries when using global register variables
  2005-05-15 23:45 [Bug tree-optimization/21596] New: [4.0/4.1 Regression] extra temporaries when using global register variables rth at gcc dot gnu dot org
@ 2005-05-15 23:57 ` pinskia at gcc dot gnu dot org
  2005-07-08  1:42 ` mmitchel at gcc dot gnu dot org
  2005-09-27 16:23 ` mmitchel at gcc dot gnu dot org
  2 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-05-15 23:57 UTC (permalink / raw)
  To: gcc-bugs


------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-15 23:57 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |missed-optimization
   Last reconfirmed|0000-00-00 00:00:00         |2005-05-15 23:57:38
               date|                            |
   Target Milestone|---                         |4.0.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21596


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [Bug tree-optimization/21596] [4.0/4.1 Regression] extra temporaries when using global register variables
  2005-05-15 23:45 [Bug tree-optimization/21596] New: [4.0/4.1 Regression] extra temporaries when using global register variables rth at gcc dot gnu dot org
  2005-05-15 23:57 ` [Bug tree-optimization/21596] " pinskia at gcc dot gnu dot org
@ 2005-07-08  1:42 ` mmitchel at gcc dot gnu dot org
  2005-09-27 16:23 ` mmitchel at gcc dot gnu dot org
  2 siblings, 0 replies; 6+ messages in thread
From: mmitchel at gcc dot gnu dot org @ 2005-07-08  1:42 UTC (permalink / raw)
  To: gcc-bugs



-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.0.1                       |4.0.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21596


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [Bug tree-optimization/21596] [4.0/4.1 Regression] extra temporaries when using global register variables
  2005-05-15 23:45 [Bug tree-optimization/21596] New: [4.0/4.1 Regression] extra temporaries when using global register variables rth at gcc dot gnu dot org
  2005-05-15 23:57 ` [Bug tree-optimization/21596] " pinskia at gcc dot gnu dot org
  2005-07-08  1:42 ` mmitchel at gcc dot gnu dot org
@ 2005-09-27 16:23 ` mmitchel at gcc dot gnu dot org
  2 siblings, 0 replies; 6+ messages in thread
From: mmitchel at gcc dot gnu dot org @ 2005-09-27 16:23 UTC (permalink / raw)
  To: gcc-bugs



-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.0.2                       |4.0.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21596


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [Bug tree-optimization/21596] [4.0/4.1 Regression] extra temporaries when using global register variables
       [not found] <bug-21596-119@http.gcc.gnu.org/bugzilla/>
  2005-10-22  4:08 ` pinskia at gcc dot gnu dot org
@ 2005-10-31  3:36 ` mmitchel at gcc dot gnu dot org
  1 sibling, 0 replies; 6+ messages in thread
From: mmitchel at gcc dot gnu dot org @ 2005-10-31  3:36 UTC (permalink / raw)
  To: gcc-bugs



------- Comment #2 from mmitchel at gcc dot gnu dot org  2005-10-31 03:36 -------
Leaving this as P2.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21596


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [Bug tree-optimization/21596] [4.0/4.1 Regression] extra temporaries when using global register variables
       [not found] <bug-21596-119@http.gcc.gnu.org/bugzilla/>
@ 2005-10-22  4:08 ` pinskia at gcc dot gnu dot org
  2005-10-31  3:36 ` mmitchel at gcc dot gnu dot org
  1 sibling, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-10-22  4:08 UTC (permalink / raw)
  To: gcc-bugs



-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |minor
   Last reconfirmed|2005-10-13 20:55:07         |2005-10-22 04:07:57
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21596


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2005-10-31  3:36 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2005-05-15 23:45 [Bug tree-optimization/21596] New: [4.0/4.1 Regression] extra temporaries when using global register variables rth at gcc dot gnu dot org
2005-05-15 23:57 ` [Bug tree-optimization/21596] " pinskia at gcc dot gnu dot org
2005-07-08  1:42 ` mmitchel at gcc dot gnu dot org
2005-09-27 16:23 ` mmitchel at gcc dot gnu dot org
     [not found] <bug-21596-119@http.gcc.gnu.org/bugzilla/>
2005-10-22  4:08 ` pinskia at gcc dot gnu dot org
2005-10-31  3:36 ` mmitchel at gcc dot gnu dot org

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