[llvm-dev] can't build/run after adding lib to Fibonacci example, even reverting the complete llvm tree does not help (original) (raw)

Michael Kruse via llvm-dev llvm-dev at lists.llvm.org
Sun Sep 23 22:27:23 PDT 2018

Am Sa., 22. Sep. 2018 um 00:12 Uhr schrieb Dennis Luehring via llvm-dev <llvm-dev at lists.llvm.org>:

first: thank you for helping out >I might try compiling your source from the VS's Developer Command Prompt: >cmake --build . --target Fibonacci >Does this work? call "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvars64.bat" cd llvm-build cmake --build . --config Debug --target Fibonacci building Fibonacci example works BUT X86CommonTableGen get rebuild again? Das Projekt "D:\projects\fun\jittests\clangfromsrc\llvm-build\lib\Target\X86\InstPrinter\LLVMX86AsmPrinter.vcxproj" (37) erstellt "D:\projects\fun\jittests\clangfromsrc\llvm-build\lib\Target\X86\X86CommonTableGen.vcxproj" (38) auf Knoten "1" (Standardziele). InitializeBuildStatus: "x64\Debug\X86CommonTableGen\X86Commo.1917F16D.tlog\unsuccessfulbuild" wird erstellt, da "AlwaysCreate" angegeben wurde. CustomBuild: Building X86GenAsmMatcher.inc... Building X86GenAsmWriter.inc... Building X86GenAsmWriter1.inc... Building X86GenCallingConv.inc... Building X86GenDAGISel.inc... Building X86GenDisassemblerTables.inc... Building X86GenEVEX2VEXTables.inc... Building X86GenFastISel.inc... Building X86GenGlobalISel.inc... ... which costs me much time (>30min) on my slow system - and i don't understand why "AlwaysCreate" is used here - i only added one lib dependencie to an example and reverted it? now the totaly unrelated big one is build again it could be that faster systems do not suffer that much from this behavior but it still does not feel right enough RAM, no swapping, just my 2 core CPU is not fast enough

No idea either why it re-reruns, but it should not be that much of an issue and not re-run when you rebuild without changes to CMakeLists. The debug version of tablegen is quite slow. You can either set LLVM_TABLEGEN/CLANG_TABLEGEN to separately compiled release version of them or use LLVM_OPTIMIZED_TABLEGEN which does that for you.

result: Fibonacci was built without errors

after building i reopened llvm-build\LLVM.sln in VS2017 ... loading 273 projects and tested what happend on selecting "build solution" - to check what else happened to build now serveral cpp getting compiled, libs/exes getting linked - i think that is related to the X86CommonTableGen rebuild another >30min waiting to "finish building" the solution inside of the IDE nearly enough RAM, started swapping on building lli.cpp :(, but get back to under 5GB Ram usage after some seconds, my 2 core CPU is still not fast enough

You may want to restrict the number of parallel project builds: Options->Projects and Solutions->Build and Run->maximum number of parallel build jobs

Michael

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