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Date: Wed, 01 Jun 2005 01:55:00 -0000
From: "tromey at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: java-prs@gcc.gnu.org
Message-ID: <20050601015434.21855.tromey@gcc.gnu.org>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug java/21855] New: array bounds checking elimination
X-Bugzilla-Reason: CC
X-SW-Source: 2005-q2/txt/msg00644.txt.bz2
List-Id: <java-prs.sourceware.org>

public class q
{
  public static void main(String[] args)
  {
    for (int i = 0; i < args.length; ++i)
      System.out.println(args[i]);
  }
}

Right now you will get an unnecessary array bounds check at 'args[i]'.
BTW we implement this check with an unsigned comparison to also weed
out negative indices.

Also, an array's size is fixed at its creation.  We ought to be
able to constant propagate in code like this:

   int[] array = new int[256];
   for (int i = 0; i < array.length; ++i) { ... }

... but afaik there is no way for the front end of the value of
'array.length'

-- 
           Summary: array bounds checking elimination
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: java
        AssignedTo: dnovillo at redhat dot com
        ReportedBy: tromey at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org,java-prs at gcc dot gnu
                    dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21855