From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-91046-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 29486 invoked by alias); 2 Apr 2004 06:00:40 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Received: (qmail 29455 invoked by uid 48); 2 Apr 2004 06:00:37 -0000
Date: Fri, 02 Apr 2004 06:00:00 -0000
From: "kazu at cs dot umass dot edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Message-ID: <20040402060018.14819.kazu@cs.umass.edu>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug optimization/14819] New: [tree-ssa] strchr is not folded at tree-level
X-Bugzilla-Reason: CC
X-SW-Source: 2004-04/txt/msg00143.txt.bz2
List-Id: <gcc-bugs.sourceware.org>

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