> From: Yilong Li [mailto:yilong...@runtimeverification.com] > Subject: Re: RV-Predict bugs
> > True, but as Mark previously pointed out, no one cares. All that happens > > in that case is the object is redundantly created and then garbage > > collected later; no damage. > No, it's not right. It's possible (although very unlikely) that this method > could return null and results in a null pointer exception later. Again, that cannot happen; see below. > Intra-thread semantics says that event 3 (the first read of the field > hashCode) happens before event 4 (the second read of field hashCode) but it > has no effect on the value event 4 can see (because event 3 is also a read > rather than a write). You're mixing up inter- and intra-thread semantics and completely ignoring the write to hashCode when the initially observed value is zero. Intra-thread semantics require that operations occur in program order, so the initial zero (or null) check results in a non-zero (or non-null) write to the field of interest; control flow cannot be ignored here. If your supposition were correct, a compiler (or CPU) would be free to migrate actions dependent on a conditional block to a spot prior to that conditional block - clearly that is nonsense. - 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: dev-unsubscr...@tomcat.apache.org For additional commands, e-mail: dev-h...@tomcat.apache.org
