[cfe-dev] speed up clang build after modifying checker code of static analyzer
Lou Wynn via cfe-dev
cfe-dev at lists.llvm.org
Wed Sep 19 14:44:33 PDT 2018
~/work/git-repos/llvm/release-git$ which clang
/usr/bin/clang
~/work/git-repos/llvm/release-git$ clang -###
clang version 3.8.0-2ubuntu4 (tags/RELEASE_380/final)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
I also tried with a self-built clang, and got the same error.
Thanks,
Lou
On 09/19/2018 02:41 PM, Kristóf Umann wrote:
> Are you using a prebuild binary? Are you sure you're using the clang
> you'd like to compile with? (`which clang`?)
>
> On 19 Sep 2018 23:38, "Lou Wynn" <lewisurn at gmail.com
> <mailto:lewisurn at gmail.com>> wrote:
>
> When I use clang to compile (gcc is fine), I got cmake error:
>
> -- Performing Test HAVE_CXX_ATOMICS_WITHOUT_LIB
> -- Performing Test HAVE_CXX_ATOMICS_WITHOUT_LIB - Failed
> -- Looking for __atomic_fetch_add_4 in atomic
> -- Looking for __atomic_fetch_add_4 in atomic - found
> -- Performing Test HAVE_CXX_ATOMICS_WITH_LIB
> -- Performing Test HAVE_CXX_ATOMICS_WITH_LIB - Failed
> CMake Error at cmake/modules/CheckAtomic.cmake:50 (message):
> Host compiler must support std::atomic!
> Call Stack (most recent call first):
> cmake/config-ix.cmake:323 (include)
> CMakeLists.txt:577 (include)
>
>
> How can I fix it? I checkout source code from the git mirror. I'm
> running ubuntu 16.04.1 LTS.
>
>
> Thanks,
> Lou
>
>
> On 09/19/2018 12:02 AM, Kristóf Umann wrote:
>> Hi!
>>
>> A couple tips I can give:
>> * Compile with clang. Make sure you use a release build for
>> this purpose, optimized with LTO. I usually just download a
>> prebuild binary and go with that. Clang tends to be about 2-3
>> times faster than gcc.
>> * For linking, use LLD, a linker part of the LLVM family.
>> Especially with -j8, it will make a significant difference. Your
>> next best option is gnu gold.
>>
>> Great to hear about a new checker! I'd encourage you to upload
>> your work in progress early on to phabricator, even if it only
>> contains an empty callback, because an entire working solution
>> (if lengthy enough) can drastically increase the time it takes to
>> review it.
>>
>> I know because I made that mistake :).
>>
>> Cheers,
>> Kristóf Umann
>>
>>
>> On 19 Sep 2018 04:06, "Lou Wynn via cfe-dev"
>> <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
>>
>> I do need debug information because tracing code is a great
>> way for me to get familiarized with clang and the static
>> analyzer.
>>
>> I've managed to run "make -j8 clang" at the top of the build
>> directory. However, the final linking process takes too long
>> now. Is there a way to build a thin version that only runs
>> the static analyzer? I think that I can at least cut the code
>> gen part out of the build process but have no idea how. The
>> only command I run is "clang -cc1 -analyze
>> -analyzer-checker=xxx" It'd be great if I could reduce the
>> final object file to few hundred megabytes.
>>
>> [ 96%] Built target clangStaticAnalyzerCore
>>
>>
>> Scanning dependencies of target clangStaticAnalyzerCheckers
>> [ 96%] Building CXX object
>> tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/clangStaticAnalyzerCheckers.dir/IntegerOverflowChecker.cpp.o
>> [ 96%] Linking CXX static library
>> ../../../../../lib/libclangStaticAnalyzerCheckers.a
>> [100%] Built target clangStaticAnalyzerCheckers
>> [100%] Linking CXX executable ../../../../bin/clang <-- this
>> take most time now
>> [100%] Built target clang
>>
>> real 2m22.707s
>> user 2m10.812s
>> sys 0m14.936s
>>
>> Thanks,
>> Lou
>>
>> On 09/18/2018 06:25 PM, Reid Kleckner wrote:
>>> If the clang binary is 2GB, I would recommend building in
>>> Release mode with assertions enabled. Linking binaries
>>> without debug information is dramatically faster. This means
>>> passing -DCMAKE_BUILD_TYPE=Release
>>> -DLLVM_ENABLE_ASSERTIONS=ON to cmake.
>>>
>>> If you use debug information, I recommend explicitly
>>> building one target, the target you are testing (usually
>>> clang), until you feel the need to run the complete clang
>>> test suite.
>>>
>>> On Tue, Sep 18, 2018 at 5:42 PM Lou Wynn via cfe-dev
>>> <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
>>>
>>> Hi,
>>>
>>> I'm writing my first clang static analyzer checker. I
>>> wrote the scaffold
>>> code to add the checker into clang. But every time when
>>> I change the
>>> checker implementation code, the build process after
>>> generating the
>>> checker object file is very slow. It's over 4 minutes in
>>> my laptop,
>>> which has the i7-6820HQ four core CPU and 32G memory.
>>> The generated
>>> clang binary is over 2G. The affected artifacts are as
>>> follows:
>>>
>>> ---------------------
>>>
>>> Scanning dependencies of target clangStaticAnalyzerCheckers
>>> [ 95%] Building CXX object
>>> tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/clangStaticAnalyzerCheckers.dir/IntegerOverflowChecker.cpp.o
>>> [ 95%] Linking CXX static library
>>> ../../../../../lib/libclangStaticAnalyzerCheckers.a
>>> [ 98%] Built target clangStaticAnalyzerCheckers
>>> [ 98%] Linking CXX executable ../../../../bin/arcmt-test
>>> [ 98%] Linking CXX executable ../../../../bin/clang-check
>>> [ 98%] Linking CXX executable ../../../../bin/clang
>>> [ 98%] Linking CXX shared library
>>> ../../../../lib/libclang.so
>>> [ 98%] Built target arcmt-test <--- this seems to take
>>> the most time
>>> [ 98%] Built target libclang
>>> [ 98%] Linking CXX executable ../../../../bin/c-arcmt-test
>>> [ 98%] Linking CXX executable ../../../../bin/c-index-test
>>> [ 98%] Built target c-arcmt-test
>>> [ 98%] Built target clang-check
>>> [ 98%] Built target clang
>>> [100%] Built target c-index-test
>>>
>>> real 4m23.014s
>>> user 8m4.032s
>>> sys 0m51.992s
>>>
>>> ---------------------
>>>
>>> How can I speed up the build process so that I don't
>>> have to wait for
>>> almost 4.5 minute for a single change in the
>>> implementation code? I only
>>> work on the checker of the static analyzer.
>>>
>>> --
>>> Thanks,
>>> Lou
>>>
>>> _______________________________________________
>>> cfe-dev mailing list
>>> cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>> <http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev>
>>>
>>
>>
>> _______________________________________________
>> cfe-dev mailing list
>> cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>> <http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev>
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20180919/2e49240a/attachment.html>
More information about the cfe-dev
mailing list