[Bug tree-optimization/20470] New: Branching sequence generated for ABS(x-y)

[Bug tree-optimization/20470] New: Branching sequence generated for ABS(x-y)

[pthaugen at us dot ibm dot com]

Noticed that gcc/g++ generate a branching sequence instead of straight-line code
for expressions of the form ABS(x-y). Changing the operator to something else
(+, *, /) resutls in straight-line code.


#define ABS(value)   ( (value)>=0 ? (value) : -(value) )
int i,j,k,l,m,n;

void f1()
{
  l = ABS(m+n);
  i = ABS(j-k);
}

-- 
           Summary: Branching sequence generated for ABS(x-y)
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pthaugen at us dot ibm dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: powerpc*-*-*
  GCC host triplet: powerpc*-*-*
GCC target triplet: powerpc*-*-*


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20470

[Bug tree-optimization/20470] Branching sequence generated for ABS(x-y)

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-14 17:12 -------
Confirmed, I know where this comes from too, SPEC (but I had forgot which test).

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
           Severity|normal                      |enhancement
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |missed-optimization
   Last reconfirmed|0000-00-00 00:00:00         |2005-03-14 17:12:47
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20470

[Bug tree-optimization/20470] Branching sequence generated for ABS(x-y)

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-14 17:13 -------
I will note I know there is an Apple radar about this bug.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20470

[Bug tree-optimization/20470] Branching sequence generated for ABS(x-y)

[pthaugen at us dot ibm dot com]

------- Additional Comments From pthaugen at us dot ibm dot com  2005-03-14 19:13 -------
I noticed this in the twolf benchmark of SPEC, dimbox.c:new_dbox_a().



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20470

[Bug tree-optimization/20470] Branching sequence generated for ABS(x-y)

[pthaugen at us dot ibm dot com]

------- Additional Comments From pthaugen at us dot ibm dot com  2005-03-14 22:29 -------
Decided to look into this myself, currently testing a patch.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20470

[Bug tree-optimization/20470] Branching sequence generated for ABS(x-y)

[pthaugen at us dot ibm dot com]

------- Additional Comments From pthaugen at us dot ibm dot com  2005-03-15 18:22 -------
Ditto here, except added additional call to negate_expr_p(arg2) to make sure it
was ok to flip the expression back to it's original form. Not sure if that was
necessary, was assuming I'd get comments when I posted a patch (hopefully soon,
had some problems with testing).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20470

[Bug tree-optimization/20470] Branching sequence generated for ABS(x-y)

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-03-25 20:08 -------
Subject: Bug 20470

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	dje@gcc.gnu.org	2005-03-25 20:08:33

Modified files:
	gcc            : ChangeLog fold-const.c 

Log message:
	2005-03-25  Pat Haugen  <pthaugen@us.ibm.com>
	
	PR tree-optimization/20470
	* fold-const.c (fold_cond_expr_with_comparison): Recognize/fold
	ABS(x-y).

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.7998&r2=2.7999
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/fold-const.c.diff?cvsroot=gcc&r1=1.550&r2=1.551



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20470

[Bug tree-optimization/20470] Branching sequence generated for ABS(x-y)

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-03-25 20:10 -------
Subject: Bug 20470

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	dje@gcc.gnu.org	2005-03-25 20:10:39

Modified files:
	gcc/testsuite  : ChangeLog 
Added files:
	gcc/testsuite/gcc.dg/tree-ssa: pr20470.c 

Log message:
	2005-03-25  Pat Haugen  <pthaugen@us.ibm.com>
	
	PR tree-optimization/20470
	* gcc.dg/tree-ssa/pr20470.c: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.5220&r2=1.5221
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/tree-ssa/pr20470.c.diff?cvsroot=gcc&r1=NONE&r2=1.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20470

[Bug tree-optimization/20470] Branching sequence generated for ABS(x-y)

[dje at gcc dot gnu dot org]

------- Additional Comments From dje at gcc dot gnu dot org  2005-03-28 21:31 -------
patch committed

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20470

[Bug tree-optimization/20470] Branching sequence generated for ABS(x-y)

[pinskia at gcc dot gnu dot org]

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20470