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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi Samuel,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Thanks for the quick response.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I agree that the best way forward would be to reduce the number of sections/symbols produced<br>in Register.cpp.o. I’m afraid I don’t know enough about this part of clang to know how feasible<br>that is.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I’m afraid I don’t really have a good target for the maximum number of sections to be produced<br>in a single object file. I think the target should be to at least halve the number of sections of what<br>is currently produced, and hope that future changes will not be creeping up the number of<br>sections again.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Kristof<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";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"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Samuel Benzaquen [mailto:sbenza@google.com] <br><b>Sent:</b> 29 August 2013 23:09<br><b>To:</b> Kristof Beyls<br><b>Cc:</b> Clang Dev; Nicholas Braden; Manuel Klimek<br><b>Subject:</b> Re: 'too many sections' again when building ASTMatchers/Dynamic/Registry.cpp on Windows<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>On Thu, Aug 29, 2013 at 3:49 PM, Kristof Beyls <<a href="mailto:kristof.beyls@arm.com" target="_blank">kristof.beyls@arm.com</a>> wrote:<o:p></o:p></p><div><div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm'><p class=MsoNormal>Hi Samuel,<br><br>We've observed that in the past few days, debug-builds with Visual Studio<br>have started failing again because too many sections are generated for<br>ASTMatchers/Dynamic/Registry.cpp.<br><br>This has been observed and discussed before in this email thread:<br><a href="http://lists.cs.uiuc.edu/pipermail/cfe-dev/2013-June/030102.html" target="_blank">http://lists.cs.uiuc.edu/pipermail/cfe-dev/2013-June/030102.html</a>.<br><br>It seems that since then, bit by bit, the number of sections for<br>Registry.cpp<br>has been creeping up. I've done a quick experiment on linux to measure how<br>the size and the number of sections in Registry.cpp.o has been increasing<br>over<br>time. The table does show that your fix in r183768 did reduce the number of<br>sections a lot; but since then, the number of sections has been increasing<br>steadily and quite rapidly.<br><br> Size of Register.cpp.o<br>svn id bytes sections<br>189448 27122264 28108<br>189353 27204656 28259<br>189031 26473624 27284<br>187500 26451288 26952<br>186000 21940824 23119<br>183769 19289872 20544<br>183768 33647984 35738<br><br>You did say on the previous email thread that you had a few more ideas on<br>how<br>to reduce the number of sections in Register.cpp.o. I'm wondering if you<br>would<br>be able to share the ideas you've got?<o:p></o:p></p></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>The problem is that there are a lot of AST nodes, and each node is getting a whole bunch of classes instantiated, many of them with virtual methods.<o:p></o:p></p></div><div><p class=MsoNormal>For example, there are around 200 symbols related to clang::WhileStmt. It instantiates TrueMatcher<clang::WhileStmt>, DynCastMatcher<clang::Stmt, , lang::WhileStmt>, BindableMatcher<clang::WhileStmt>, MatcherInterface<clang::WhileStmt>, SingleNodeMatcherInterface<clang::WhileStmt>, VariadicOperatorMatcherInterface<clang::WhileStmt>, Matcher<clang::WhileStmt>::WrappedMatcher, Matcher<clang::WhileStmt>, IdMatcher<clang::WhileStmt>.<o:p></o:p></p></div><div><p class=MsoNormal>All of these have virtual methods, which means that there are 2 symbols per constructor, 3 for the destructor and 1 for the vtable. This is without counting the actual methods in the class.<o:p></o:p></p></div><div><p class=MsoNormal>We then do more method/class instantiations for the dynamic binding.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>The main fix I wanted to try is to reduce the number of classes that get instantiated. On the previous fix I removed vector<T> and list<T> for each AST node. I just replaced those uses with plain arrays.<o:p></o:p></p></div><div><p class=MsoNormal>I will do another round of fixes. Do you have a target size/sections ?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm'><p class=MsoNormal>At the moment, it seems clang cannot be build with visual studio in debug<br>mode; and the large file size of Register.cpp.o and the large number of<br>sections seems to be slowing down the compile process on other platforms<br>too.<o:p></o:p></p></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>In the worst case we could use plan A, which was splitting Register.cpp into many smaller files. We don't need to have all this code in the same compilation unit. I wanted to avoid doing this because it doesn't help to the total size of the objects and makes the code more complex.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>_Sam<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm'><p class=MsoNormal style='margin-bottom:12.0pt'><br>Thanks,<br><br>Kristof<br><br><o:p></o:p></p></blockquote></div><p class=MsoNormal><o:p> </o:p></p></div></div></div></div></body></html>