<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br><div><div>On Apr 22, 2014, at 12:07 PM, Hal Finkel <<a href="mailto:hfinkel@anl.gov">hfinkel@anl.gov</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;">Hrmm; interesting. Is this the behavior we want? I'd be inclined to say that the pragma should imply safety.</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"></blockquote></div><br><div>I prefer to implement ‘unsafe’ vectorization with a separate pragma keyword. I would like to discourage users from using this option because it can break the correctness of their program, and I think that ’safe’ is a better default. Vectorizing a loop in an ‘unsafe’ mode adds a risk and marking the loop with the ‘unsafe’ keyword makes the decision explicit and documents. </div><div>I think that it is reasonable to require users to write: #pragma vectorize unsafe width(4) … </div><div><br></div><div>Thanks,</div><div>Nadav</div></body></html>