[GSoC 2025] Enabling Out-Of-Process JIT Execution in CppInterOp

.github/actions/Build_LLVM/action.yml

@@ -43,6 +43,10 @@ runs:
           ninja LLVMOrcDebugging -j ${{ env.ncpus }}
           ninja clingInterpreter -j ${{ env.ncpus }}
         else
+          if [[ "${{ matrix.oop-jit }}" == "On" ]]; then
+            git apply -v ../patches/llvm/clang20-1-out-of-process.patch
+            echo "Apply clang20-1-out-of-process.patch:"
+          fi
           cd build
           cmake -DLLVM_ENABLE_PROJECTS="${{ matrix.llvm_enable_projects}}" \
                 -DLLVM_TARGETS_TO_BUILD="${{ matrix.llvm_targets_to_build }}"  \
@@ -58,6 +62,14 @@ runs:
                 -DLLVM_INCLUDE_TESTS=OFF                        \
                 ../llvm
           ninja clang clangInterpreter clangStaticAnalyzerCore -j ${{ env.ncpus }}
+          if [[ "${{ matrix.oop-jit }}" == "On" ]]; then
+            if [[ "${{ matrix.os }}" == macos* ]]; then
+              SUFFIX="_osx"
+            elif [[ "${{ matrix.os }}" == ubuntu* ]]; then
+              SUFFIX="-x86_64"
+            fi
+            ninja clang-repl llvm-jitlink-executor orc_rt${SUFFIX} -j ${{ env.ncpus }}       
+          fi
           cd ./tools/
           rm -rf $(find . -maxdepth 1 ! -name "clang" ! -name ".")
           cd ..

.github/actions/Build_and_Test_CppInterOp/action.yml

@@ -48,6 +48,7 @@ runs:
                 -DCODE_COVERAGE=${{ env.CODE_COVERAGE }}     \
                 -DCMAKE_INSTALL_PREFIX=$CPPINTEROP_DIR       \
                 -DLLVM_ENABLE_WERROR=On                      \
+                -DLLVM_BUILT_WITH_OOP_JIT=${{ matrix.oop-jit }} \
                 ../
         fi
         docs_on=$(echo "${{ matrix.documentation }}" | tr '[:lower:]' '[:upper:]')
@@ -60,6 +61,9 @@ runs:
           if [[ "${os}" != "macos"* ]]; then
             valgrind --show-error-list=yes --track-origins=yes --error-exitcode=1 unittests/CppInterOp/CppInterOpTests/unittests/bin/${{ env.BUILD_TYPE }}/CppInterOpTests
           fi
+          if [[ "${{ matrix.oop-jit }}" == "On" ]]; then
+            ./unittests/CppInterOp/CppInterOpTests/unittests/bin/${{ env.BUILD_TYPE }}/CppInterOpTests --use-oop-jit
+          fi
         fi
         echo "CB_PYTHON_DIR=$CB_PYTHON_DIR" >> $GITHUB_ENV
         echo "CPPINTEROP_BUILD_DIR=$CPPINTEROP_BUILD_DIR" >> $GITHUB_ENV

.github/workflows/main.yml

@@ -23,15 +23,6 @@ jobs:
       matrix:
         include:
           # Ubuntu Arm Jobs
-          - name: ubu22-arm-gcc12-clang-repl-20-coverage
-            os: ubuntu-22.04-arm
-            compiler: gcc-12
-            clang-runtime: '20'
-            cling: Off
-            cppyy: Off
-            llvm_enable_projects: "clang"
-            llvm_targets_to_build: "host;NVPTX"
-            coverage: true
           - name: ubu24-arm-gcc12-clang-repl-20
             os: ubuntu-24.04-arm
             compiler: gcc-12
@@ -66,6 +57,16 @@ jobs:
             llvm_enable_projects: "clang"
             llvm_targets_to_build: "host;NVPTX"
           # Ubuntu X86 Jobs
+          - name: ubu22-x86-gcc12-clang-repl-20-coverage
+            os: ubuntu-22.04
+            compiler: gcc-12
+            clang-runtime: '20'
+            cling: Off
+            cppyy: Off
+            llvm_enable_projects: "clang;compiler-rt"
+            llvm_targets_to_build: "host;NVPTX"
+            coverage: true
+            oop-jit: On
           - name: ubu24-x86-gcc12-clang-repl-20
             os: ubuntu-24.04
             compiler: gcc-12
@@ -74,6 +75,15 @@ jobs:
             cppyy: Off
             llvm_enable_projects: "clang"
             llvm_targets_to_build: "host;NVPTX"
+          - name: ubu24-x86-gcc12-clang-repl-20-out-of-process
+            os: ubuntu-24.04
+            compiler: gcc-12
+            clang-runtime: '20'
+            cling: Off
+            cppyy: Off
+            llvm_enable_projects: "clang;compiler-rt"
+            llvm_targets_to_build: "host;NVPTX"
+            oop-jit: On
           - name: ubu24-x86-gcc12-clang-repl-19-cppyy
             os: ubuntu-24.04
             compiler: gcc-12
@@ -100,6 +110,15 @@ jobs:
             llvm_enable_projects: "clang"
             llvm_targets_to_build: "host;NVPTX"
           # MacOS Arm Jobs
+          - name: osx15-arm-clang-clang-repl-20-out-of-process
+            os: macos-15
+            compiler: clang
+            clang-runtime: '20'
+            cling: Off
+            cppyy: Off
+            llvm_enable_projects: "clang;compiler-rt"
+            llvm_targets_to_build: "host"
+            oop-jit: On
           - name: osx15-arm-clang-clang-repl-20
             os: macos-15
             compiler: clang
@@ -218,9 +237,9 @@ jobs:
       id: cache
       with:
         path: |
-          llvm-project
-          ${{ matrix.cling=='On' && 'cling' || '' }}
-        key: ${{ env.CLING_HASH }}-${{ runner.os }}-${{ matrix.os }}-${{ matrix.compiler }}-clang-${{ matrix.clang-runtime }}.x-patch-${{ hashFiles(format('patches/llvm/clang{0}-*.patch', matrix.clang-runtime)) || 'none' }}
+              llvm-project
+              ${{ matrix.cling=='On' && 'cling' || '' }}
+        key: ${{ env.CLING_HASH }}-${{ runner.os }}-${{ matrix.os }}-${{ matrix.compiler }}-clang-${{ matrix.clang-runtime }}.x-patch-${{ hashFiles(format('patches/llvm/clang{0}-*.patch', matrix.clang-runtime)) || 'none' }}${{ matrix.oop-jit == 'On' && '-oop' || '' }}
 
     - name: Setup default Build Type
       uses: ./.github/actions/Miscellaneous/Select_Default_Build_Type

CMakeLists.txt

@@ -298,6 +298,18 @@ include_directories(SYSTEM ${LLVM_INCLUDE_DIRS})
 separate_arguments(LLVM_DEFINITIONS_LIST NATIVE_COMMAND ${LLVM_DEFINITIONS})
 add_definitions(${LLVM_DEFINITIONS_LIST})
 
+string(REGEX REPLACE "/build/lib/cmake/llvm$" "" LLVM_SOURCE_DIR "${LLVM_DIR}")
+add_definitions(-DLLVM_SOURCE_DIR="${LLVM_SOURCE_DIR}")
+
+if(LLVM_BUILT_WITH_OOP_JIT)
+  if((CMAKE_SYSTEM_NAME STREQUAL "Darwin" AND CMAKE_SYSTEM_PROCESSOR MATCHES "arm64") OR
+     (CMAKE_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64"))
+    add_definitions(-DLLVM_BUILT_WITH_OOP_JIT)
+  else()
+    message(FATAL_ERROR "LLVM_BUILT_WITH_OOP_JIT is only supported on Darwin arm64 or Linux x86_64. Build aborted.")
+  endif()
+endif()
+
 # If the llvm sources are present add them with higher priority.
 if (LLVM_BUILD_MAIN_SRC_DIR)
   # LLVM_INCLUDE_DIRS contains the include paths to both LLVM's source and
@@ -379,6 +391,7 @@ string(REPLACE "-Wcovered-switch-default" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}
 
 file(STRINGS "VERSION" CPPINTEROP_VERSION)
 string(REPLACE "." ";" VERSION_LIST "${CPPINTEROP_VERSION}")
+
 list(GET VERSION_LIST 0 CPPINTEROP_VERSION_MAJOR)
 list(GET VERSION_LIST 1 CPPINTEROP_VERSION_MINOR)
 list(GET VERSION_LIST 2 CPPINTEROP_VERSION_PATCH)

README.md

@@ -111,6 +111,13 @@ git clone --depth=1 --branch release/20.x https://github.com/llvm/llvm-project.g
 cd llvm-project
 ```
 
+If you want to have out-of-process JIT execution enabled in CppInterOp, then apply this patch on Linux and MacOS environment.
+> Note that this patch will not work for Windows because out-of-process JIT execution is currently implemented for Linux and MacOS only.
+
+```bash
+git apply -v ../CppInterOp/patches/llvm/clang20-1-out-of-process.patch
+```
+
 ##### Build Clang-REPL
 
 Clang-REPL is an interpreter that CppInterOp works alongside. Build Clang (and
@@ -202,6 +209,28 @@ and clone cppyy-backend repository where we will be installing the CppInterOp li
 git clone --depth=1 https://github.com/compiler-research/cppyy-backend.git
 ```
 
+##### Build Clang-REPL with Out-of-Process JIT Execution
+
+To have ``Out-of-Process JIT Execution`` enabled, run following commands to build clang and clang-repl to support this feature:
+> Only for Linux x86_64 and Macos amr64
+```bash
+mkdir build 
+cd build 
+cmake -DLLVM_ENABLE_PROJECTS="clang;compiler-rt"                   \
+              -DLLVM_TARGETS_TO_BUILD="host;NVPTX"                \
+              -DCMAKE_BUILD_TYPE=Release                          \
+              -DLLVM_ENABLE_ASSERTIONS=ON                         \
+              -DCLANG_ENABLE_STATIC_ANALYZER=OFF                  \
+              -DCLANG_ENABLE_ARCMT=OFF                            \
+              -DCLANG_ENABLE_FORMAT=OFF                           \
+              -DCLANG_ENABLE_BOOTSTRAP=OFF                        \
+              ../llvm
+
+## For Linux x86_64
+cmake --build . --target clang clang-repl llvm-jitlink-executor orc_rt-x86_64 --parallel $(nproc --all)
+## For MacOS arm64
+cmake --build . --target clang clang-repl llvm-jitlink-executor orc_rt_osx --parallel $(sysctl -n hw.ncpu)
+
 #### Build Cling and related dependencies
 
 The Cling interpreter and depends on its own customised version of `llvm-project`,
@@ -265,6 +294,35 @@ Now CppInterOp can be built. This can be done by executing
 ```bash
 mkdir CppInterOp/build/
 cd CppInterOp/build/
+
+```
+
+On Windows execute
+
+```powershell
+mkdir CppInterOp\build\
+cd CppInterOp\build\
+```
+
+Now if you want to build CppInterOp with Clang-REPL then execute the following commands on Linux and MacOS
+
+```bash
+cmake -DBUILD_SHARED_LIBS=ON -DLLVM_DIR=$LLVM_DIR/build/lib/cmake/llvm -DClang_DIR=$LLVM_DIR/build/lib/cmake/clang -DCMAKE_INSTALL_PREFIX=$CPPINTEROP_DIR ..
+cmake --build . --target install --parallel $(nproc --all)
+```
+
+and
+
+> Do make sure to pass ``DLLVM_BUILT_WITH_OOP_JIT=ON``, if you want to have out-of-process JIT execution feature enabled.
+
+```powershell
+cmake -DLLVM_DIR=$env:LLVM_DIR\build\lib\cmake\llvm -DClang_DIR=$env:LLVM_DIR\build\lib\cmake\clang -DCMAKE_INSTALL_PREFIX=$env:CPPINTEROP_DIR ..
+cmake --build . --target install --parallel $env:ncpus
+```
+
+on Windows. If alternatively you would like to install CppInterOp with Cling then execute the following commands on Linux and MacOS
+
+```bash
 cmake -DBUILD_SHARED_LIBS=ON -DCPPINTEROP_USE_CLING=ON -DCPPINTEROP_USE_REPL=Off -DCling_DIR=$LLVM_DIR/build/tools/cling -DLLVM_DIR=$LLVM_DIR/build/lib/cmake/llvm -DClang_DIR=$LLVM_DIR/build/lib/cmake/clang -DCMAKE_INSTALL_PREFIX=$CPPINTEROP_DIR ..
 cmake --build . --target install --parallel $(nproc --all)
 ```

docs/InstallationAndUsage.rst

@@ -41,6 +41,15 @@ Clone the 20.x release of the LLVM project repository.
    git clone --depth=1 --branch release/20.x https://github.com/llvm/llvm-project.git
    cd llvm-project
 
+If you want to have out-of-process JIT execution enabled in CppInterOp, then apply this patch on Linux and MacOS environment.
+.. note::
+
+   This patch will not work for Windows because out-of-process JIT execution is currently implemented for Linux and MacOS only.
+
+.. code:: bash
+
+   git apply -v ../CppInterOp/patches/llvm/clang20-1-out-of-process.patch
+
 ******************
  Build Clang-REPL
 ******************
@@ -99,6 +108,36 @@ On Windows you execute the following
    $env:LLVM_DIR= $PWD.Path
    cd ..\
 
+***************************************************
+Build Clang-REPL with Out-of-Process JIT Execution
+***************************************************
+
+To have `Out-of-Process JIT Execution` enabled, run following commands to build clang and clang-repl to support this feature:
+
+.. note::
+
+   Only for Linux x86_64 and Macos arm64
+
+.. code:: bash
+
+   mkdir build 
+   cd build 
+   cmake -DLLVM_ENABLE_PROJECTS="clang;compiler-rt"                   \
+                  -DLLVM_TARGETS_TO_BUILD="host;NVPTX"                \
+                  -DCMAKE_BUILD_TYPE=Release                          \
+                  -DLLVM_ENABLE_ASSERTIONS=ON                         \
+                  -DCLANG_ENABLE_STATIC_ANALYZER=OFF                  \
+                  -DCLANG_ENABLE_ARCMT=OFF                            \
+                  -DCLANG_ENABLE_FORMAT=OFF                           \
+                  -DCLANG_ENABLE_BOOTSTRAP=OFF                        \
+                  ../llvm
+
+   # For Linux x86_64
+   cmake --build . --target clang clang-repl llvm-jitlink-executor orc_rt-x86_64 --parallel $(nproc --all)
+
+   # For MacOS arm64
+   cmake --build . --target clang clang-repl llvm-jitlink-executor orc_rt_osx --parallel $(sysctl -n hw.ncpu)
+
 **************************************
  Build Cling and related dependencies
 **************************************
@@ -263,6 +302,10 @@ commands on Linux and MacOS
    cmake -DBUILD_SHARED_LIBS=ON -DLLVM_DIR=$LLVM_DIR/build/lib/cmake/llvm -DClang_DIR=$LLVM_DIR/build/lib/cmake/clang -DCMAKE_INSTALL_PREFIX=$CPPINTEROP_DIR ..
    cmake --build . --target install --parallel $(nproc --all)
 
+.. note::
+
+   Do make sure to pass ``DLLVM_BUILT_WITH_OOP_JIT=ON``, if you want to have out-of-process JIT execution feature enabled.
+
 and
 
 .. code:: powershell

include/CppInterOp/CppInterOp.h

@@ -19,6 +19,7 @@
 #include <cstdint>
 #include <set>
 #include <string>
+#include <sys/types.h>
 #include <vector>
 
 // The cross-platform CPPINTEROP_API macro definition
@@ -964,6 +965,12 @@ CPPINTEROP_API void CodeComplete(std::vector<std::string>& Results,
 ///\returns 0 on success, non-zero on failure.
 CPPINTEROP_API int Undo(unsigned N = 1, TInterp_t interp = nullptr);
 
+#ifndef _WIN32
+/// Returns the process ID of the executor process.
+/// \returns the PID of the executor process.
+CPPINTEROP_API pid_t GetExecutorPID();
+#endif
+
 } // end namespace Cpp
 
 #endif // CPPINTEROP_CPPINTEROP_H