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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-GB link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>Hi Kevin,<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Yes, I am aware of all of this (i.e. the way shared libraries work on Windows and of the auto-importing feature in MinGW gcc). However, I can’t explain to myself why I got that message for </span><span style='color:#1F497D'>llvm::CallInst and no other LLVM function…?! Also, I would rather MinGW gcc work the way it ought to on Windows, rather than find a way around the problem, no matter how convenient it may be.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Alan</span><span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> Kevin Kelley [mailto:kevin@kelleysoft.com] <br><b>Sent:</b> 03 December 2011 13:52<br><b>To:</b> Alan Garny<br><b>Cc:</b> llvmdev@cs.uiuc.edu<br><b>Subject:</b> Re: [LLVMdev] LLVM 3.0 - Windows - auto-importing issue with llvm::CallInst<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><br>On 12/2/2011 9:09 AM, Alan Garny wrote: <o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'>However, there is one new (minor) issue which is that when building my application I get a warning from the linker about auto-importing having been activated without –enable-auto-import being specified on the command line. Indeed, for some reason, the vtable for llvm::CallInst has to be resolved…?! This is clearly not critical since I can get rid of the warning by adding –enable-auto-import on the command line, but I wish I didn’t have to do that (it’s not clean in my view).</span><o:p></o:p></p><p class=MsoNormal><span style='color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Mostly harmless... for shared libs on Windows you'd normally have to either: <br>use __declspec(dllexport) on exported functions, and __declspec(dllimport)<br>on the prototypes for code that uses them; or:<br>list symbols to be exported in a .def file when building the dll, and<br>link with that .def file when building code that uses it.<br><br>GCC on mingw came up with the "auto-import" option to avoid those<br>nuisances by, automatically exporting everything, if otherwise there'd<br>be no exports and you're building a shared-lib. When it does this<br>without being told to, it emits that warning message, so you know<br>it happened.<br><br>I think that that warning went away in later versions -- this seems<br>to be the most-appropriate behavior and apparently doesn't<br>cause problems, so for GCC, auto-import and no special markings<br>on your code is what you should usually do.<br><br>But I'm not an expert -- just trying to follow along. There are<br>potential issues with relocations and thunks and position-independent<br>code and intermittent failures when DLL relocations "collide"...<br>but I really don't want to have to worry about that. <br><br><br>Kevin<br><br>(a couple interesting links ab't enable-auto-import):<br><br>[1] <a href="http://sourceware.org/binutils/docs-2.16/ld/WIN32.html">http://sourceware.org/binutils/docs-2.16/ld/WIN32.html</a><br>[2] <a href="http://www.delorie.com/gnu/docs/binutils/ld_4.html">http://www.delorie.com/gnu/docs/binutils/ld_4.html</a><br><br><br><br><o:p></o:p></span></p></div></div></body></html>