[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 14:38:33 PDT 2018
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
>>
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>
>
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