Re: Java static analysis tool (JavaChecker) has been released

"Joachim Durchholz" <joachim_d@gmx.de>
3 Dec 2002 00:42:13 -0500

          From comp.compilers

Related articles
Java static analysis tool (JavaChecker) has been released ronih@luukku.com (Roni Hursti) (2002-11-17)
Re: Java static analysis tool (JavaChecker) has been released sander@haldjas.folklore.ee (Sander Vesik) (2002-12-01)
Re: Java static analysis tool (JavaChecker) has been released joachim_d@gmx.de (Joachim Durchholz) (2002-12-03)
| List of all articles for this month |

From: "Joachim Durchholz" <joachim_d@gmx.de>
Newsgroups: comp.compilers
Date: 3 Dec 2002 00:42:13 -0500
Organization: Compilers Central
References: 02-11-090 02-12-027
Keywords: arithmetic, comment
Posted-Date: 03 Dec 2002 00:42:13 EST

John wrote:
  > [Right shifting three bits is not the same as dividing by 8. That's a
  > famous optimizer bug from way back. -John]


Is it still a bug if it's an arithmetic shift on a two's complement machine?
One thing that I can think of is how your integer division rounds for
negative numbers: towards zero or towards negative infinity. If it's
towards negative infinity, an arithmetic right shift should handle this
correctly (if I did my math correctly).
Are there other factors?


Regards,
Joachim
[That's the problem. If you know that the dividend is non-negative,
shifting is OK. -John]


Post a followup to this message

Return to the comp.compilers page.
Search the comp.compilers archives again.