Need reviewer: JDK 8 CR for Support Integer overflow (original) (raw)

Roger Riggs Roger.Riggs at oracle.com
Fri Feb 3 14:46:33 UTC 2012


The boolean expression can be refactored. (Only bit-31 is significant). But it becomes pretty inscrutable.

(x ^ r)< 0&& (x ^ y)>= 0 becomes

(x ^ r)< 0&& (~(x ^ y))< 0 becomes

((x ^ r)& ~(x ^ y))< 0

Roger

On 02/03/2012 07:12 AM, Florian Weimer wrote:

* Eamonn McManus:

On 3 February 2012 00:11, Florian Weimer<fweimer at bfk.de> wrote: Would it make sense to replace (x ^ r)< 0&& (x ^ y)>= 0 with (x ^ y ^ r)< 0? That would not be correct. For example, it would signal overflow for -1 + 1. Oops. But there has to be a way to implement this using just one comparison.



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