<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><html>Hi Nick,</html><div><div><br></div><div><div>On Mar 28, 2008, at 02:15, Nick Lewycky wrote:</div><div><br></div><div></div></div><div><blockquote type="cite">Before I start investing time implementing these changes, does anyone foresee any problems that I missed?</blockquote><div><font class="Apple-style-span" color="#144FAE"><br></font></div></div><div>Stepping back from the nuts and bolts for a moment, could you precisely define what constitutes a predecessor in this model?</div><div><br></div><div>What blocks would a phi node in %catch require for a case like this?</div><div><br></div></div><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; ">define i8 @f(i1 %b) {</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; ">entry:</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "> b label %try</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; ">try: unwinds to %catch</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "> b i1 %b, label %then, label %else</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; ">then: unwinds to %catch</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "> ret void</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; ">else: unwinds to %catch</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "> ret void</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; ">catch: ; What are my predecessors?</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; "> ret void</blockquote><blockquote class="webkit-indent-blockquote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 40px; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; ">}</blockquote><div><br></div><div><blockquote type="cite">B. redefine the dominator tree by modifying the GraphTraits<br> i. A dom B means that all instructions in A are guaranteed to execute before any instructions in B.<br> ii. the domtree may have multiple roots.<br><br>Multiple roots occurs when the entry block 'unwinds to' another block.</blockquote><div><br></div><div>It seems highly problematical that static allocas might not dominate their uses. The entry block is already special in that it cannot be used as a branch target. Why not also forbid 'unwinds to' on the entry block?</div><div><br></div><div>— Gordon</div></div><div></div><html><br></html></div></body></html>