Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!gegeweb.org!eternal-september.org!feeder.eternal-september.org!.POSTED!not-for-mail
From: markspace <-@.>
Newsgroups: comp.lang.java.programmer
Subject: Re: Java puzzler
Date: Thu, 12 May 2011 19:26:20 -0700
Organization: A noiseless patient Spider
Lines: 41
Message-ID: <iqi4sh$poa$1@dont-email.me>
References: <4db69c13-878f-4806-adb2-a3c5adb1c48c@glegroupsg2000goo.googlegroups.com> <qrGdnWE1mOKFHVfQnZ2dnUVZ_uKdnZ2d@earthlink.com> <alpine.DEB.2.00.1105112141410.27211@urchin.earth.li> <I6SdnROEzeMni1bQnZ2dnUVZ_sKdnZ2d@earthlink.com> <alpine.DEB.2.00.1105122029030.7602@urchin.earth.li> <-8mdnSRPEIdA21HQnZ2dnUVZ_j2dnZ2d@earthlink.com> <iqhhim$blg$4@speranza.aioe.org> <iqhjks$798$1@dont-email.me> <AcCdnflMosQt-lHQnZ2dnUVZ_t2dnZ2d@earthlink.com> <iqhumi$750$1@dont-email.me> <jY-dnS9ZV4RyG1HQnZ2dnUVZ_tadnZ2d@earthlink.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Fri, 13 May 2011 02:26:26 +0000 (UTC)
Injection-Info: mx01.eternal-september.org; posting-host="IPG0uhtItDWol02AtwWFWQ"; logging-data="26378"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1/+MqBthpIv15ip4hR2k9ngu3pE/uGiiM4="
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10
In-Reply-To: <jY-dnS9ZV4RyG1HQnZ2dnUVZ_tadnZ2d@earthlink.com>
Cancel-Lock: sha1:ghzGdBD2cOqxLMMfb84qqFj6vds=
Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:4036

On 5/12/2011 6:18 PM, Patricia Shanahan wrote:
> and add rules for deciding when to do overflow detection.
>

What I envision is only to only add the deciding in the compiler, not at 
run time.

I'm not talking about setting a mode per thread or application.  I only 
want to affect what byte codes get generated at compile time. 
Everything already compiled or compiled with existing options retains 
its current semantics.

For example, if I do something like this

   public int encryptAndCount( byte[] buffer ) {
     @strictint  // assume this turns on overflow checking
     int i = 0;
     int count = 0;
     while( buffer[i] != 0 ) { // assume null terminated
       count++;
       encrypt( buffer, i );
     }
     return count;
   }

and encrypt is something like this:

public class Encrypt {
   private static byte rand;
   public static void encrypt( byte[] buffer, int i offset ) {
      rand += 42;  // world's worst encryption
      buffer[offset] ^= rand;
   }
}

the method encryptAndCount has overflow detection, but that does not 
"flow into" the method encrypt.  They are distinct compilation units, 
and in this case I immagine that "@strictint" only applies to one method 
at a time anyway.  So it all depends on the byte codes, not threads or 
program flow, and doesn't happen dynamically at run time.