libllvmext

Extensions on top of LLVM for Kotlin/Native.

src/main/include contains C headers extending LLVM C API. From these headers Kotlin/JVM bindings are generated in llvmInterop. Kotlin additions should be prefixed with LLVMKotlin.

src/main/cpp contains C++ sources. The sources should follow LLVM coding convention. Kotlin additions should be put inside llvm::kotlin.

FileCheck is used for testing custom LLVM passes. Use ./gradlew :kotlin-native:libllvmext:test to run all the tests. The tests are declared in testData/fileCheck as .ll files. The tests consist of

• OPT: and FILECHECK: directives to set additional arguments for opt and FileCheck tools
• LLVM code on which opt will be run
• CHECK: directives for FileCheck, which are run on the opt output; see also FileCheck docs) for additional CHECK-* directives
• output of opt can be found in build/fileCheck/ with the same name as the test file.

To help with code formatting, .clang-format file is placed in this folder. :kotlin-native:libllvmext:clangFormat task can be used to run git-clang-format -f $(git merge-base origin/master HEAD) -- kotlin-native/libllvmext/, which will format only the changed files. The task accepts optional --parent=<branch> (to specify a branch other than origin/master) and --interactive (which adds -p flag to git-clang-format to interactively accept or reject formatting patches).

Custom LLVM passes

Custom LLVM passes live in the Passes directory:

• HideSymbolsPass (kotlin-hide-symbols): similar to internalize but makes symbols hidden instead of internal; the symbols remain visible during compilation, but are hidden by the linker in the final binary.
• PrepareThreadSanitizerPass (kotlin-tsan): function pass, that applies sanitize_thread attribute to all defined functions; can't simply be done in the code generator, because we want this applied to the runtime as well, which is shipped as LLVM bitcode.
• PrepareStackProtectorPass (kotlin-ssp): function pass, that applies ssp attribute to all defined functions; can be configured as kotlin-ssp<strong> or kotlin-ssp<req> to apply sspstrong or sspreq respectively; can't simply be done in the code generator, because we want this applied to the runtime as well, which is shipped as LLVM bitcode.