<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jan 12, 2016 at 9:59 AM, Mehdi Amini <span dir="ltr"><<a href="mailto:mehdi.amini@apple.com" target="_blank">mehdi.amini@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><br><div><span class=""><blockquote type="cite"><div>On Jan 12, 2016, at 8:50 AM, David Blaikie <<a href="mailto:dblaikie@gmail.com" target="_blank">dblaikie@gmail.com</a>> wrote:</div><br><div><div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jan 12, 2016 at 8:41 AM, Mehdi Amini <span dir="ltr"><<a href="mailto:mehdi.amini@apple.com" target="_blank">mehdi.amini@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word">You need to be careful that an LTO build won’t inline and eliminate this.</div></blockquote><div><br></div><div>fair - but these calls, if they'd executed, would've been totally bogus, right? (they would've crashed/null dereferenced, etc)<br><br>So somehow this code is live without it actually executing.<br></div></div></div></div></div></blockquote><div><br></div></span><div>Sure it won’t execute because of the guard: if (std::getenv("bar") != (char*) -1) return;</div><div><br></div><div>But my point was more than taking the address and not doing anything with it is not the same as calling a function, I mentioned it because I’m not sure what you had in mind to make sure the pointer always escape (printf like Tobias suggested should work).</div><span class=""><br><blockquote type="cite"><div><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div><br>To come back to the underlying issue: What is it we're trying to solve here? What entities are we trying to preserve & why are more traditional/normal ways of preserving them insufficient? (sorry if this is too much of a derailment/the rest of you have enough context here, feel free to go on without me ;))</div></div></div></div></div></blockquote><div><br></div></span><div>What is a “more traditional/normal way of preserving” symbols? Export lists?</div></div></div></blockquote><div><br></div><div>Well, at the most basic level - if this code is needed it must be called from somewhere, why is that insufficient to ensure it is linked into the binary?<br><br>Alternatively: What breaks if this code is removed/these things aren't preserved?</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div><span class=""><div><br></div><div>— </div><div>Mehdi</div><div><br></div><div><br></div><br><blockquote type="cite"><div><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div><div><div><br><div><blockquote type="cite"><div>On Jan 12, 2016, at 8:02 AM, David Blaikie via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a>> wrote:</div><br><div><div dir="ltr">Do you need to call anything? Could you just take the address of the function and return it, stuff it in a global, or otherwise escape it?</div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jan 12, 2016 at 12:02 AM, Dimitry Andric via llvm-commits <span dir="ltr"><<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">dim added a subscriber: grosser.<br>
<br>
================<br>
Comment at: include/llvm/LinkAllPasses.h:191<br>
@@ -190,3 +196,3 @@<br>
<span> llvm::RGPassManager RGM;<br>
- ((llvm::RegionPass*)nullptr)->runOnRegion((llvm::Region*)nullptr, RGM);<br>
</span> llvm::AliasSetTracker X(*(llvm::AliasAnalysis*)nullptr);<br>
----------------<br>
@grosser, you originally added this part in rL117263 ("Reference RegionPass to stop it being eliminated"), do you have any suggestions? If the goal is to to unsure RegionPass.cpp is linked in, I think we can call `RegionPass::createPrinterPass()` instead.<br>
<div><div><br>
<br>
<a href="http://reviews.llvm.org/D15996" rel="noreferrer" target="_blank">http://reviews.llvm.org/D15996</a><br>
<br>
<br>
<br>
_______________________________________________<br>
llvm-commits mailing list<br>
<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a><br>
<a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits" rel="noreferrer" target="_blank">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits</a><br>
</div></div></blockquote></div><br></div>
_______________________________________________<br>llvm-commits mailing list<br><a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a><br><a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits" target="_blank">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits</a><br></div></blockquote></div><br></div></div></div></div></blockquote></div><br></div></div>
</div></blockquote></span></div><br></div></blockquote></div><br></div></div>