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</o:shapelayout></xml><![endif]--></head><body lang=DE link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>> </span><span lang=EN-US>cmake -G "MinGW Makefiles" \<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> -DCMAKE_INSTALL_PREFIX=C:\LLVM \<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> -DCMAKE_BUILD_TYPE=Debug \<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> -DLLVM_ENABLE_ASSERTIONS=On \<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> -DLLVM_TARGETS_TO_BUILD=X86 \<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> </span>-DLLVM_ENABLE_CXX1Y=On \<o:p></o:p></p><p class=MsoNormal> ../<o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>CMAKE_BUILD_TYPE=Debug will result in a non-optimized compiler. Although I don’t have numbers at hand, you might want to set CMAKE_BUILD_TYPE=Release.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>Regards,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>Jonas</span><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> cfe-dev [mailto:cfe-dev-bounces@lists.llvm.org] <b>On Behalf Of </b>Nikodemus Siivola via cfe-dev<br><b>Sent:</b> Thursday, June 1, 2017 9:43 AM<br><b>To:</b> cfe-dev@lists.llvm.org<br><b>Subject:</b> [cfe-dev] clang-cl.exe (32bit) dog slow, capping at ~16.5% CPU<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>I was wondering why compiles were so slow and noticed that clang-cl.exe is never consuming more than ~16.5% CPU on my laptop. This is an i7-7700HQ, 32GB memory, running Windows 10 Pro.<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Memory and disk use appear trivial as well, and the computer was otherwise mostly idle at the time. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Compiling a trivial hello-world takes 11 seconds:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>$ clang --version</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>clang version 4.0.1</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>Target: i686-pc-windows-msvc</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>Thread model: posix</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>InstalledDir: C:\LLVM\bin</span><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>$ cat foo.cpp</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>#include <iostream></span><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>int main()</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>{</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'> std::cout << "Yo" << std::endl;</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'> return 0;</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>}</span><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>$ time clang-cl foo.cpp</span><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>real 0m11.886s</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>user 0m0.015s</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Courier New"'>sys 0m0.015s</span><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Compiling the same program under the Linux subsystem and clang-3.5 takes 0.16seconds. The Visual Studio commandline compiler is likewise almost instant.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>This is release_40 from one of the git mirrors, build built as part of the LLVM tree using Visual Studio 2015 command prompt, with (I think, not 100% sure, don't know cmake well enough to figure out after the fact) the following cmake invovations:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><div><p class=MsoNormal>cmake -G "MinGW Makefiles" \<o:p></o:p></p></div><div><p class=MsoNormal> -DCMAKE_INSTALL_PREFIX=C:\LLVM \<o:p></o:p></p></div><div><p class=MsoNormal> -DCMAKE_BUILD_TYPE=Debug \<o:p></o:p></p></div><div><p class=MsoNormal> -DLLVM_ENABLE_ASSERTIONS=On \<o:p></o:p></p></div><div><p class=MsoNormal> -DLLVM_TARGETS_TO_BUILD=X86 \<o:p></o:p></p></div><div><p class=MsoNormal> -DLLVM_ENABLE_CXX1Y=On \<o:p></o:p></p></div><div><p class=MsoNormal> ../<o:p></o:p></p></div></div><div><p class=MsoNormal>cmake --build .<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Did I pick spectacularly stupid build options or something?<o:p></o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt'><br>Any suggestions for figuring out what is going on? (Windows is not my regular platform so I'm a bit out of depth here.)<o:p></o:p></p><div><p class=MsoNormal>Cheers,<o:p></o:p></p></div></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> -- nikodemus<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div></div></div></body></html>