<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>On Aug 14, 2007, at 00:23, Chris Lattner wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">On Mon, 13 Aug 2007, Gordon Henriksen wrote:</div></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"> <blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-style-span" style="-webkit-text-stroke-width: -1; ">Changing these structures breaks binary compatibility (including C interop).</span></div></blockquote></blockquote><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">If that is so, and if there is no way around this, then it makes sense to develop some compatibility mode.<span class="Apple-converted-space"> </span>How does native C code generate these tables?</div></blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; ">I might've conflated two related points. The frametable isn't really at issue with respect to C interop. Rather, the decision to get into the runtime business is.</div><br class="webkit-block-placeholder"></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; ">To be specific, C interop doesn't generate frame table entries. It anchors roots by explicitly registering/unregistering root pads with the runtime. Very similar to the paper you cited, although not a stack.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br class="webkit-block-placeholder"></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; ">C interop does (from macros) use runtime information directly derived from the data/text bracketing symbols I also mentioned.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><blockquote type="cite"> <blockquote type="cite"><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-style-span" style="-webkit-text-stroke-width: -1; "> and then walk the stack with the llvm_cg_walk_gcroots function. Note that these are not well tested and probably have holes in them, but these are the interfaces we want to use :)</span></div></blockquote></blockquote><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">But here I have to disagree. Quite by design, LLVM lacks an existing runtime to leverage: LLVM CLR. In light of that, it is difficult to justify ignoring a mature runtime that does exist in order to avoid building a simple data structure.</div> </blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Sure.<span class="Apple-converted-space"> </span>Given a lack of current implementation, if the ocaml implementation would work and meet our needs, I have no problem with adopting/stealing it :)</div></blockquote><div><br class="webkit-block-placeholder"></div><div>I'm not sure you want to incorporate ocaml's runtime per se; its object model is very unique. :) How do you envision LLVM GC support going?</div><div><br class="webkit-block-placeholder"></div><div>My thinking was to merely extend LLVM to be a less "uncooperative environment" for GC (as the paper you referenced put it), while maintaining neutrality to the runtime and object model.</div><div><br class="webkit-block-placeholder"></div><div>The two major problems I had really boil down to identifying GC points in machine code and statically identifying live roots at those GC points, both problems common to many collection techniques. Looking at the problem from that perspective makes the problem much more tractable, actually…</div><div><br class="webkit-block-placeholder"></div><blockquote type="cite"> <blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><span class="Apple-style-span" style="-webkit-text-stroke-width: -1; ">[2] ocaml is licensed under the QPL [Trolltech/KDE], which has an onerous distribution clause which prohibits forks. My current work leaves the existing code generator in place, touching only a few files to integrate LLVM code generation as a runtime option; this improves the possibility that a patch would be accepted, and otherwise makes patch maintenance manageable.</span></div></blockquote><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">We can work around this on our end going forward.</div></blockquote><div><br class="webkit-block-placeholder"></div><div>How so?</div><br><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">What this means in the short term is that we can't accept any Ocaml-project code into LLVM. <span class="Apple-style-span" style="-webkit-text-stroke-width: -1; ">This does not prevent the ocaml people from using LLVM code though.</span></div></blockquote><br></div><div>Exactly. ocaml is written in itself, so there's little likelihood of that becoming a problem. :)</div><div><br></div><div><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Trebuchet MS; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; ">— Gordon<br class="Apple-interchange-newline"></span></span></span></span></span></span> </div><br></body></html>