[cfe-dev] Building Clang on Windows

Sat Oct 6 15:57:20 PDT 2018

Is this the result of a vs update or you synced to a more recent llvm
revision when building?
On Sat, Oct 6, 2018 at 3:22 PM Matt Asplund (mwasplund) <mwasplund at gmail.com>
wrote:

> I just wanted to chime in that I am also seeing issues on VS builds. After
> the latest update building clang in VS2017 is suddenly using all 16 gigs of
> memory and thrashes my paging. It was working fine last week.
>
> -Matt
>
> Sent from my iPhone
>
> On Oct 6, 2018, at 2:53 PM, Zachary Turner via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
> Windows (and all other operating systems) use swap space, so even if you
> actually do run out of memory, it will start using your hard disk instead.
> So it’s really almost impossible to run out of memory unless there’s a
> 32-bit process somewhere. I’m guessing it’s MSBuild.exe
> On Sat, Oct 6, 2018 at 2:46 PM Fábio Picchi <fabio.exe at gmail.com> wrote:
>
>> I have 8GB available and had no other application running besides Visual
>> Studio during the build process.
>>
>> I guess I might be running out of memory but wouldn't that be too much? I
>> am not used to Windows so I can't say for sure.
>>
>> On Sat, Oct 6, 2018 at 6:32 PM Kim Gräsman <kim.grasman at gmail.com> wrote:
>>
>>> Are you sure you're not just running out of memory?
>>>
>>> If swap is disabled and VS consumes more memory than ninja as a
>>> baseline, I guess a memory-demanding compile step could fail like this.
>>>
>>> I recently saw similar failures with GCC on Linux for SemaExprMember.cpp
>>> on a memory-constrained system.
>>>
>>> - Kim
>>>
>>> On Sat, Oct 6, 2018, 22:24 Fábio Picchi via cfe-dev <
>>> cfe-dev at lists.llvm.org> wrote:
>>>
>>>> Tried to build clang using the updated Visual Studio 2017 and got the
>>>> same error.
>>>>
>>>> Good news is that building with ninja worked.
>>>>
>>>> That is quite puzzling... I don't know if anyone else was able to
>>>> reproduce the issue I was having but it makes zero sense that building with
>>>> the VS toolset raises a compiler error and building with ninja, using the
>>>> same compiler, doesn't. I don't know how to further debug this problem but
>>>> I would love to help if any of you would have a suggestion on how to
>>>> approach it.
>>>>
>>>>
>>>>
>>>> On Sat, Oct 6, 2018 at 8:31 AM Fábio Picchi <fabio.exe at gmail.com>
>>>> wrote:
>>>>
>>>>> My path to cl.exe
>>>>> C:\Program Files (x86)\Microsoft Visual
>>>>> Studio\2017\Community\VC\Tools\MSVC\14.14.26428\bin\HostX64\x64\CL.exe
>>>>>
>>>>> > If it's running out of heap space on the amd64 native toolchain,
>>>>> it's a bug in the compiler because this should not even be theoretically
>>>>> possible
>>>>> I will try to update visual studio to see if the problem is solved.
>>>>>
>>>>> > we can build with ninja
>>>>> I will also try to build with ninja :) I had never heard about the
>>>>> project!
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Thu, Oct 4, 2018 at 11:44 AM Zachary Turner <zturner at google.com>
>>>>> wrote:
>>>>>
>>>>>> compiler out of heap space is quite interesting.  I can understand
>>>>>> the linker running out of heap space, but the compiler is quite unusual.
>>>>>> The first thing I would do is check to make sure you are using the 64-bit
>>>>>> host toolchain.  You said you passed -Thost=x64, but let's make sure
>>>>>> there's not a bug in the Visual Studio generator or something.
>>>>>>
>>>>>> Turn on Diagnostic output (Tools -> Options -> Projects & Solutions
>>>>>> -> Build and Run -> MSBuild Project Output Verbosity -> Diagnostic) and
>>>>>> rebuild.  Then rebuild and wait for the error to happen.  When it does,
>>>>>> find the error in the log and scroll up looking for "cl.exe" (or do a
>>>>>> reverse find from the end).
>>>>>>
>>>>>> Look at the path to cl.exe.  Is it the one from the amd64 directory
>>>>>> or the x86 directory?
>>>>>>
>>>>>> If it's running out of heap space on the amd64 native toolchain, it's
>>>>>> a bug in the compiler because this should not even be theoretically
>>>>>> possible.  If it's running out of heap space on the x86 toolchain, then the
>>>>>> question is why isn't it using the correct toolchain.
>>>>>>
>>>>>> FWIW, I kind of wish we would stop supporting building with the VS
>>>>>> generator.  MSBuild doesn't really scale well, and now that VS has support
>>>>>> for opening CMake projects directly, and we can build with ninja, I don't
>>>>>> see a strong use case for building with MSBuild anymore given how many
>>>>>> problems it causes.
>>>>>>
>>>>>> On Thu, Oct 4, 2018 at 6:24 AM Fábio Picchi via cfe-dev <
>>>>>> cfe-dev at lists.llvm.org> wrote:
>>>>>>
>>>>>>> Updates:
>>>>>>> > Are you building debug or release? If debug, try building release.
>>>>>>> I tried and got the same error.
>>>>>>>
>>>>>>> I noticed my *build target* was *Win32* even though I passed the
>>>>>>> option -Thost=x64 to cmake. I followed the new instructions to regenerate
>>>>>>> the solution using:
>>>>>>> cmake -G "Visual Studio 15 2017" -A x64 -Thost=x64 ..\llvm
>>>>>>>
>>>>>>> Now the build target is displayed as *x64*. I tried to build it in
>>>>>>> Debug mode and still got the dreaded error:
>>>>>>> C1060: compiler is out of heap space
>>>>>>>
>>>>>>> I couldn't check the log errors in detail because I had to leave for
>>>>>>> work but I'll post more updates in the evening.
>>>>>>>
>>>>>>> I will try to do some research on the weekend but it would be great
>>>>>>> if someone could better explain the out of heap space error. How can the
>>>>>>> linker run out of memory just by linking binaries? Why is this process so
>>>>>>> memory intensive? Furthermore, why does it matter if I am targeting x86 or
>>>>>>> x64? I understand the pointers double in size but that would mean more
>>>>>>> memory usage for the x64 target, not the x86.
>>>>>>>
>>>>>>> Thank you very much for the help!
>>>>>>>
>>>>>>> On Thu, Oct 4, 2018 at 4:19 AM Dennis Luehring via cfe-dev <
>>>>>>> cfe-dev at lists.llvm.org> wrote:
>>>>>>>
>>>>>>>> Am 03.10.2018 um 23:29 schrieb Reid Kleckner via cfe-dev:
>>>>>>>> > Can anyone who actually knows answer Shaob's question? He asked
>>>>>>>> "Does the
>>>>>>>> > Win64 generator automatically imply -Thost=x64?
>>>>>>>>
>>>>>>>>
>>>>>>>> CMake gives a warning if not using -Thost=x64 with VS2017 generator
>>>>>>>> Win64 that i could happen that the x86 tool chain is used - so i
>>>>>>>> think
>>>>>>>> its not automatically implied
>>>>>>>>
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