<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Jan 12, 2010, at 1:26 PM, Blaine Garst wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">The compiler initializes the first word of every block to one of two symbols (the other being <span class="Apple-style-span" style="font-family: Monaco; font-size: 10px; ">_NSConcreteStackBlock)</span>, that being one of them, so as to enable Objective-C treating blocks as objects if and when the objc runtime is loaded. The blocks runtime for the most part ignores these values until such a time. A block copy operation will use another symbol, so in total I think you'll need <span class="Apple-style-span" style="color: rgb(53, 131, 136); font-family: Monaco; font-size: 10px; ">_NSConcreteMallocBlock <span class="Apple-style-span" style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; ">also.</span></span></div></blockquote><div><br></div><div>This runtime support code is available at <a href="http://compiler-rt.llvm.org/">http://compiler-rt.llvm.org/</a></div><div><br></div><div>-Chris</div><div><br></div></div></body></html>