LLVM Clang Static-Analysis

Building and Running LLVM-Clang Static Analyzer

Posted by Nithin on 2020-06-02

Building LLVM From source

I am documenting how I am building LLVM Clang in my Mac Air 2015.

  • macOS Mojave 10.14.6
  • 1.6 GHz Intel Core i5
  • 8 GB Memory

    Get the source code

    git clone https://github.com/llvm/llvm-project.git

    Build the code (I am using ninja to build)

    mkdir $ROOT/llvm-project/build
    cd $ROOT/llvm-project/build
    cmake -G Ninja \
        -DDEFAULT_SYSROOT="$(xcrun --show-sdk-path)" \
        -DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi" \
        -DCMAKE_BUILD_TYPE=Release ../llvm
    ninja clang
    ninja cxx

Apparently we need to build libc++: by running ninja cxx other wise we get some header errors.

Running LLVM-Clang Static Analyzer

To run a static analyzer on test.cpp file, we can use scan-build utility with below command.

$ROOT/llvm-project/clang/tools/scan-build/bin/scan-build -k -V \
    --use-analyzer $ROOT/llvm-project/build/bin/clang -o . clang -c ./test.cpp

Options

  • -V option it will open the report in the browser
  • -k keep on going option
  • c Only run preprocess, compile, and assemble steps

alt text

Or we can use it via clang to run a specific check. Here for example NullDereference

$ROOT/llvm-project/build/bin/clang++ -cc1 -analyze -analyzer-checker=core.NullDereference test.cpp

Summary

Full build took around 2.5 hours in my machine.
Building after a small change took around 1 minute.

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