[llvm-dev] Windows build strangeness

Wed May 16 14:07:06 PDT 2018

With VS2013 I found that editing a CMakeLists.txt file caused CMake to be re-run successfully and the build to also continue successfully, but since I switched to VS2015 the CMake re-run occurs - apparently successfully, but more often than not the build failed afterwards from either the IDE and from MSBuild.  Since I seldom change the CMakeLists.txt files, I simply do a clean CMake configuration anytime I do change them.  I also use the "Build" rather than "Rebuild" for incremental development.

	MartinO

-----Original Message-----
From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Michael Kruse via llvm-dev
Sent: 16 May 2018 21:26
To: Reid Kleckner <rnk at google.com>
Cc: llvm-dev <llvm-dev at lists.llvm.org>; Valentin Churavy <v.churavy at gmail.com>
Subject: Re: [llvm-dev] Windows build strangeness

msbuild is is able to re-run cmake if a CMakeLists.txt changes. CMake adds a special project "ZERO_CHECK" that does this. However, I am not sure it runs when invoking on the individual projects instead of the solution.

Try the cmake --build command, which should output the following:

> cmake --build . --target opt
CMake is re-running because
C:/Users/Meinersbur/build/llvm/vc15_debug_x86/tools/polly/CMakeFiles/generate.stamp
is out-of-date.
[...]

Michael

2018-05-16 15:08 GMT-05:00 Reid Kleckner via llvm-dev <llvm-dev at lists.llvm.org>:
> I think MSBuild isn't capable of re-running cmake and then reloading 
> the project files when CMakeLists.txt changes. It re-runs cmake, but 
> then continues the build with the stale projects. That probably 
> explains the "PipSqueek.cxx doesn't exist" errors. As for the link 
> error, it could also be caused by things like a file rename not getting picked up by MSBuild.
>
> The fix is probably to always run cmake before MSBuild in the nightly job.
> This isn't necessary if you are using ninja or make, if those are options.
>
> On Wed, May 16, 2018 at 12:59 PM via llvm-dev 
> <llvm-dev at lists.llvm.org>
> wrote:
>>
>> Here are a couple of representative errors.  C:\Dev\upstream\gitmono 
>> is where I keep my clone.
>>
>>
>>
>>        "C:\Dev\upstream\gitmono\wbuild\ALL_BUILD.vcxproj" (Rebuild 
>> target)
>> (1) ->
>>
>>
>> "C:\Dev\upstream\gitmono\wbuild\unittests\Support\DynamicLibrary\SecondLib.vcxproj"
>> (default target) (170:2) ->
>>
>>          c1xx : fatal error C1083: Cannot open source file:
>> 'C:\Dev\upstream\gitmono\llvm-project\llvm\unittests\Suppor
>>
>>        t\DynamicLibrary\PipSqueak.cxx': No such file or directory 
>> [C:\Dev\upstream\gitmono\wbuild\unittests\Support\Dyn
>>
>>        amicLibrary\SecondLib.vcxproj]
>>
>>
>>
>>        "C:\Dev\upstream\gitmono\wbuild\ALL_BUILD.vcxproj" (Rebuild 
>> target)
>> (1) ->
>>
>>        "C:\Dev\upstream\gitmono\wbuild\tools\llvm-mca\llvm-mca.vcxproj"
>> (default target) (339:2) ->
>>
>>        (Link target) ->
>>
>>          Backend.obj : error LNK2019: unresolved external symbol "public:
>> virtual bool __cdecl mca::FetchStage::isReady
>>
>>        (void)const " (?isReady at FetchStage@mca@@UEBA_NXZ) referenced 
>> in function "public: void __cdecl mca::Backend::run
>>
>>        (void)" (?run at Backend@mca@@QEAAXXZ) 
>> [C:\Dev\upstream\gitmono\wbuild\tools\llvm-mca\llvm-mca.vcxproj]
>>
>>
>>
>>
>>
>>
>>
>> From: Valentin Churavy [mailto:v.churavy at gmail.com]
>> Sent: Wednesday, May 16, 2018 1:54 PM
>> To: Robinson, Paul
>> Cc: llvm-dev at lists.llvm.org
>> Subject: Re: [llvm-dev] Windows build strangeness
>>
>>
>>
>> What kind of missing symbols are you getting?
>>
>> I had to work around dependencies for a Mingw32 build. See
>> https://reviews.llvm.org/D44650
>>
>> On Wed, May 16, 2018, 13:13 via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>>
>> I have the git monorepo, and Visual Studio 2015.  I am finding that 
>> running a build from the command line with msbuild (as a nightly job) 
>> invariably fails on the first try, and succeeds on a retry.
>>
>> The first msbuild command looks like this:
>>
>> msbuild ALL_BUILD.vcxproj /p:Configuration="RelWithDebInfo" /m:6 
>> /t:Rebuild
>>
>> This appears to compile everything okay, but invariably fails with 
>> some set of link-time errors, reporting missing symbols.  Then I run 
>> msbuild again, but without the /t:Rebuild (thus it's a dirty build 
>> the second time) and this succeeds.
>>
>> Is there some inadequacy in the CMake dependencies somewhere, so that 
>> some links are trying to happen before the libraries are completely 
>> finished?  Or just an msbuild issue?
>>
>> I made my nightly script check for errors and run the second round, 
>> because it has been happening so consistently, but a proper build 
>> system shouldn't require such a workaround.
>>
>> For reference, I generated the sln/project files like this:
>>
>> cmake -G "Visual Studio 14 Win64" -Thost=x64 ^
>>   -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_OPTIMIZED_TABLEGEN=ON ^
>>   -DLLVM_ENABLE_PROJECTS="llvm;clang;clang-tools-extra" ^
>>   ..\llvm-project\llvm
>>
>> (Yes I know the optimized tablegen comes from a separate tree, that's 
>> built separately and always works.  It's just the main build that 
>> fails.)
>>
>> Thanks,
>> --paulr
>>
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