> From: David Jencks [mailto:[email protected]]
> Subject: Re: RV-Predict bugs
> I have been having a hard time believing the reordering claims, but finally I
> went to Jeremy's
> blog post. To recap, he says
> if (hash == 0) {
> int h = //compute hash
> hash = h;
> }
> return hash;
> can be reordered to
> r1 = hash;
> if (hash == 0) {
> r1 = hash = // calculate hash
> }
> return r1;
> Obviously this last version is susceptible to returning 0.
> It looks to me like the 2nd version is not a reordering of the java
> statements of the first version.
Correct; it's different logic, and thus a bit of a red herring. It introduces
a timing window not present in the original code; it's not an example of a
speculative read.
- Chuck
THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY
MATERIAL and is thus for use only by the intended recipient. If you received
this in error, please contact the sender and delete the e-mail and its
attachments from all computers.
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
