[Bug optimization/14819] New: [tree-ssa] strchr is not folded at tree-level

[Bug optimization/14819] New: [tree-ssa] strchr is not folded at tree-level

[kazu at cs dot umass dot edu]

Consider:

extern char *strchr (__const char *__s, int __c) __attribute__ ((__pure__));

int
foo (void)
{
  int c = '1';
  return (strchr ("<12ers", c) == 0);
}

Here is the last tree form.

foo ()
{
<bb 0>:
  return strchr ("<12ers", 49) == 0B;

}

This strchr seems to be optimized at expand time.

As you might guess from the above testcase, GCC has a lot of redundant
IS_EXPR_CODE_CLASS(CLASS), where CLASS is a compile-time constant.
Optimizing these strchr away in turn allows us to remove a lot of dead code.

It seems to be a simple extension to call simplify_builtin_strchr() from
tree-ssa-ccp.c.

-- 
           Summary: [tree-ssa] strchr is not folded at tree-level
           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=14819

[Bug optimization/14819] [tree-ssa] strchr is not folded at tree-level

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-04-02 06:03 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2004-04-02 06:03:04
               date|                            |
   Target Milestone|---                         |tree-ssa


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14819

[Bug optimization/14819] [tree-ssa] strchr is not folded at tree-level

[kazu at cs dot umass dot edu]

------- Additional Comments From kazu at cs dot umass dot edu  2004-04-02 06:18 -------
Another possible place for this optimization would be fold_builtin().


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14819

[Bug optimization/14819] [tree-ssa] strchr is not folded at tree-level

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2004-04-02 14:10 -------
This should be folded in ccp.  Mind if I make this my weekend project?

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2004-04-02 06:03:04         |2004-04-02 14:10:29
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14819

[Bug tree-optimization/14819] [tree-ssa] strchr is not folded at tree-level

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-05-20 19:44 -------
Patch here: <http://gcc.gnu.org/ml/gcc-patches/2004-05/msg01275.html>.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14819

[Bug tree-optimization/14819] [tree-ssa] strchr is not folded at tree-level

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-05-24 01:22 -------
The patch was approved with the modification suggested by RTH.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14819

[Bug tree-optimization/14819] [tree-ssa] strchr is not folded at tree-level

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-05-30 21:05 -------
Subject: Bug 14819

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	kazu@gcc.gnu.org	2004-05-30 21:05:21

Modified files:
	gcc            : ChangeLog builtins.c 

Log message:
	PR tree-optimization/14819
	* builtins.c (fold_builtin_strchr): New.
	(fold_builtin_1): Handle BUILT_IN_STRCHR and BUILT_IN_STRRCHR
	with fold_builtin_strchr().

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.3792&r2=2.3793
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/builtins.c.diff?cvsroot=gcc&r1=1.327&r2=1.328



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14819

[Bug tree-optimization/14819] [tree-ssa] strchr is not folded at tree-level

[kazu at cs dot umass dot edu]

------- Additional Comments From kazu at cs dot umass dot edu  2004-05-30 21:07 -------
Just checked in a patch:

http://gcc.gnu.org/ml/gcc-cvs/2004-05/msg01066.html

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14819