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

[Dennis Luehring via llvm-dev]

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\jit_tests\clang_from_src\llvm-build\lib\Target\X86\InstPrinter\LLVMX86AsmPrinter.vcxproj" 
(37) erstellt 
"D:\projects\fun\jit_tests\clang_from_src\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

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

 >Otherwise, there might be some workarounds. E.g. Unload the
 >"ZERO_CHECK" project from the IDE so it does not reconfigure (or just
 >run cmake from outside the IDE before building).
 >Or start the IDE from
 >the Developer Command Prompt so the right environment variables are
 >set.

will check that later - it just costs me way too much time to get to 
this point (Fibonacci from outside, finish build of solution inside 
IDE), currently nearly 2 hours :(

beside "i don't really know what im doing" and the short swapping 
problem the workflow/build optimization of the CMake scripts feels 
strange, not very optimal
is that a windows/VStudio generator only effect (and no one is using 
that, or everyone got more cores/RAM?) or how does this usually work? 
other CMake based projects do not behave like this on my system

as a side note: i also got VS2010 and VS2015 installed on my build system


Am 21.09.2018 um 19:20 schrieb Michael Kruse:
> I might try compiling your source from the VS's Developer Command Prompt:
>
> cmake --build . --target Fibonacci
>
> Does this work?
>
> Otherwise, there might be some workarounds. E.g. Unload the
> "ZERO_CHECK" project from the IDE so it does not reconfigure (or just
> run cmake from outside the IDE before building). Or start the IDE from
> the Developer Command Prompt so the right environment variables are
> set.
>
> Michael