[cccl.c] Introduce minimal compilation support for host freestanding mode

CMakePresets.json

@@ -406,6 +406,14 @@
         "CCCL_C_Parallel_ENABLE_HEADER_TESTING": true
       }
     },
+    {
+      "name": "cccl-c-parallel-hostjit",
+      "displayName": "CCCL C Parallel Library (HostJIT)",
+      "inherits": "cccl-c-parallel",
+      "cacheVariables": {
+        "CCCL_C_Parallel_ENABLE_HOSTJIT": true
+      }
+    },
     {
       "name": "cccl-c-stf",
       "displayName": "CCCL C CUDASTF Library",
@@ -638,6 +646,10 @@
       "name": "cccl-c-parallel",
       "configurePreset": "cccl-c-parallel"
     },
+    {
+      "name": "cccl-c-parallel-hostjit",
+      "configurePreset": "cccl-c-parallel-hostjit"
+    },
     {
       "name": "cccl-c-stf",
       "configurePreset": "cccl-c-stf"
@@ -917,6 +929,11 @@
       "configurePreset": "cccl-c-parallel",
       "inherits": "base"
     },
+    {
+      "name": "cccl-c-parallel-hostjit",
+      "configurePreset": "cccl-c-parallel-hostjit",
+      "inherits": "base"
+    },
     {
       "name": "cccl-c-stf",
       "configurePreset": "cccl-c-stf",

c/parallel/CMakeLists.txt

@@ -8,6 +8,11 @@ option(
   "Build cccl.c.parallel standalone headers."
   OFF
 )
+option(
+  CCCL_C_Parallel_ENABLE_HOSTJIT
+  "Build HostJIT testing infrastructure (requires LLVM fetch, ~20 min first build)."
+  OFF
+)
 
 # FIXME Ideally this would be handled by presets and install rules, but for now
 # consumers may override this to control the target location of cccl.c.parallel.
@@ -27,6 +32,9 @@ file(
   "src/*.cpp"
 )
 
+# hostjit sources are built as a separate library; exclude from cccl.c.parallel
+list(FILTER srcs EXCLUDE REGEX "src/hostjit/")
+
 add_library(cccl.c.parallel SHARED ${srcs})
 set_property(TARGET cccl.c.parallel PROPERTY POSITION_INDEPENDENT_CODE ON)
 cccl_configure_target(cccl.c.parallel DIALECT 20)
@@ -48,6 +56,10 @@ cccl_get_thrust()
 
 add_subdirectory(src/jit_templates)
 
+if (CCCL_C_Parallel_ENABLE_HOSTJIT)
+  add_subdirectory(src/hostjit)
+endif()
+
 set_target_properties(cccl.c.parallel PROPERTIES CUDA_RUNTIME_LIBRARY STATIC)
 target_link_libraries(
   cccl.c.parallel

c/parallel/src/hostjit/CMakeLists.txt

@@ -0,0 +1,211 @@
+cmake_minimum_required(VERSION 3.20)
+
+# --------------------------------------------------------------------------
+# LLVM/Clang/LLD — fetched via CPM as static libraries
+# --------------------------------------------------------------------------
+# CPM.cmake is at the cccl repo root: cccl/cmake/CPM.cmake
+# From c/parallel/src/hostjit/ that's ../../../../cmake/CPM.cmake
+set(_cccl_cmake_dir "${CMAKE_CURRENT_SOURCE_DIR}/../../../../cmake")
+if (EXISTS "${_cccl_cmake_dir}/CPM.cmake")
+  include("${_cccl_cmake_dir}/CPM.cmake")
+else()
+  message(FATAL_ERROR "CPM.cmake not found at ${_cccl_cmake_dir}/CPM.cmake")
+endif()
+
+if (MSVC AND CMAKE_BUILD_TYPE STREQUAL "Debug")
+  message(
+    FATAL_ERROR
+    "hostjit does not support Debug builds on Windows. "
+    "The statically-linked LLVM Debug build is too large and causes stack "
+    "overflows at runtime. Use MinSizeRel, Release, or RelWithDebInfo instead."
+  )
+endif()
+
+set(HOSTJIT_LLVM_VERSION "llvmorg-22.1.1" CACHE STRING "LLVM git tag to fetch")
+
+# List options must be set before CPMAddPackage
+set(LLVM_ENABLE_PROJECTS "clang;lld" CACHE STRING "" FORCE)
+set(LLVM_TARGETS_TO_BUILD "X86;NVPTX" CACHE STRING "" FORCE)
+
+CPMAddPackage(
+  NAME llvm_project
+  GIT_REPOSITORY https://github.com/llvm/llvm-project.git
+  GIT_TAG ${HOSTJIT_LLVM_VERSION}
+  GIT_SHALLOW ON
+  SOURCE_SUBDIR llvm
+  EXCLUDE_FROM_ALL YES
+  OPTIONS
+    "LLVM_BUILD_LLVM_C_DYLIB OFF"
+    "LLVM_BUILD_TOOLS OFF"
+    "LLVM_BUILD_UTILS OFF"
+    "LLVM_BUILD_RUNTIME OFF"
+    "LLVM_BUILD_RUNTIMES OFF"
+    "LLVM_INCLUDE_BENCHMARKS OFF"
+    "LLVM_INCLUDE_DOCS OFF"
+    "LLVM_INCLUDE_EXAMPLES OFF"
+    "LLVM_INCLUDE_RUNTIMES OFF"
+    "LLVM_INCLUDE_TESTS OFF"
+    "LLVM_INCLUDE_TOOLS ON"
+    "LLVM_INCLUDE_UTILS OFF"
+    "LLVM_ENABLE_ZLIB OFF"
+    "LLVM_ENABLE_ZSTD OFF"
+    "LLVM_ENABLE_TERMINFO OFF"
+    "LLVM_ENABLE_BINDINGS OFF"
+    "CLANG_BUILD_TOOLS OFF"
+    "CLANG_ENABLE_ARCMT OFF"
+    "CLANG_ENABLE_STATIC_ANALYZER OFF"
+)
+
+# Ensure the clang resource directory exists
+file(
+  MAKE_DIRECTORY "${llvm_project_BINARY_DIR}/lib/clang/${LLVM_VERSION_MAJOR}"
+)
+
+# Find CUDA toolkit (may already be found by parent)
+if (NOT CUDAToolkit_FOUND)
+  find_package(CUDAToolkit)
+endif()
+
+# --------------------------------------------------------------------------
+# hostjit library
+# --------------------------------------------------------------------------
+add_library(hostjit_lib compiler.cpp config.cpp loader.cpp jit_compiler.cpp)
+
+# CCCL_SOURCE_DIR points to the cccl repo root
+# From c/parallel/src/hostjit -> c/parallel/src -> c/parallel -> c -> cccl
+cmake_path(GET CMAKE_CURRENT_SOURCE_DIR PARENT_PATH _src_dir) # c/parallel/src
+cmake_path(GET _src_dir PARENT_PATH _c_parallel_dir) # c/parallel
+cmake_path(GET _c_parallel_dir PARENT_PATH _c_dir) # c
+cmake_path(GET _c_dir PARENT_PATH _cccl_root) # cccl
+
+target_include_directories(
+  hostjit_lib
+  PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}/include
+    ${_c_parallel_dir}/include
+    ${llvm_project_SOURCE_DIR}/llvm/include
+    ${llvm_project_BINARY_DIR}/include
+    ${llvm_project_SOURCE_DIR}/clang/include
+    ${llvm_project_BINARY_DIR}/tools/clang/include
+    ${llvm_project_SOURCE_DIR}/lld/include
+    ${llvm_project_BINARY_DIR}/tools/lld/include
+)
+
+target_compile_definitions(
+  hostjit_lib
+  PRIVATE
+    CCCL_C_EXPERIMENTAL=1
+    CCCL_SOURCE_DIR="${_cccl_root}"
+    CLANG_RESOURCE_DIR="${llvm_project_BINARY_DIR}/lib/clang/${LLVM_VERSION_MAJOR}"
+    CLANG_HEADERS_DIR="${llvm_project_SOURCE_DIR}/clang/lib/Headers"
+    HOSTJIT_INCLUDE_DIR="${CMAKE_CURRENT_SOURCE_DIR}/include"
+)
+
+if (CUDAToolkit_FOUND)
+  target_include_directories(hostjit_lib PUBLIC ${CUDAToolkit_INCLUDE_DIRS})
+  cmake_path(GET CUDAToolkit_BIN_DIR PARENT_PATH CUDA_TOOLKIT_ROOT_FROM_CMAKE)
+  target_compile_definitions(
+    hostjit_lib
+    PRIVATE
+      CUDA_TOOLKIT_PATH="${CUDA_TOOLKIT_ROOT_FROM_CMAKE}"
+      CUDA_SDK_VERSION="${CUDAToolkit_VERSION_MAJOR}.0"
+  )
+endif()
+
+# Link against LLVM/Clang/LLD
+target_link_libraries(
+  hostjit_lib
+  PUBLIC
+    # LLVM
+    LLVMCore
+    LLVMSupport
+    LLVMIRReader
+    LLVMMC
+    LLVMObject
+    LLVMX86CodeGen
+    LLVMX86AsmParser
+    LLVMX86Desc
+    LLVMX86Info
+    LLVMNVPTXCodeGen
+    LLVMNVPTXDesc
+    LLVMNVPTXInfo
+    LLVMLinker
+    LLVMPasses
+    # Clang
+    clangAST
+    clangBasic
+    clangCodeGen
+    clangDriver
+    clangFrontend
+    clangFrontendTool
+    clangLex
+    clangParse
+    clangSema
+    clangEdit
+    clangAnalysis
+    clangRewrite
+    clangSerialization
+    # LLD
+    $<IF:$<PLATFORM_ID:Windows>,lldCOFF,lldELF>
+    lldCommon
+)
+
+if (NOT WIN32)
+  target_link_libraries(hostjit_lib PUBLIC dl)
+endif()
+
+if (CUDAToolkit_FOUND)
+  target_link_libraries(hostjit_lib PUBLIC CUDA::cuda_driver CUDA::cudart)
+  # nvJitLink and nvfatbin are required at link and runtime.
+  # nvptxcompiler is a transitive dep of libnvJitLink_static.
+  # Prefer static variants on non-Windows; fall back to the dynamic imported target;
+  # fall back further to find_library in case FindCUDAToolkit didn't create the target
+  # (e.g. partial CTK installs on Ubuntu or Windows).
+  foreach (_lib nvJitLink nvptxcompiler nvfatbin)
+    if (NOT WIN32 AND TARGET CUDA::${_lib}_static)
+      target_link_libraries(hostjit_lib PUBLIC CUDA::${_lib}_static)
+    elseif (TARGET CUDA::${_lib})
+      target_link_libraries(hostjit_lib PUBLIC CUDA::${_lib})
+    else()
+      find_library(
+        _hostjit_${_lib}
+        NAMES ${_lib}
+        HINTS
+          "${CUDAToolkit_LIBRARY_DIR}"
+          "${CUDAToolkit_ROOT}/lib/x64"
+          "${CUDAToolkit_ROOT}/lib64"
+          "${CUDAToolkit_ROOT}/lib"
+      )
+      if (_hostjit_${_lib})
+        message(STATUS "hostjit: linking ${_lib} from ${_hostjit_${_lib}}")
+        target_link_libraries(hostjit_lib PUBLIC "${_hostjit_${_lib}}")
+      else()
+        message(
+          FATAL_ERROR
+          "hostjit requires ${_lib} but it was not found.\n"
+          "  Ubuntu:  apt-get install libnvfatbin-<maj>-<min> or libnvjitlink-<maj>-<min>\n"
+          "  Windows: reinstall the CUDA toolkit and ensure the nvfatbin/nvjitlink "
+          "components are selected."
+        )
+      endif()
+    endif()
+  endforeach()
+endif()
+
+if (NOT MSVC)
+  target_compile_options(hostjit_lib PRIVATE -fno-rtti)
+endif()
+
+set_target_properties(
+  hostjit_lib
+  PROPERTIES CXX_STANDARD 20 POSITION_INDEPENDENT_CODE ON
+)
+
+# On Windows with multi-config generators (Visual Studio), exclude hostjit
+# targets from Debug builds — the LLVM Debug build causes stack overflows.
+if (MSVC)
+  set_target_properties(
+    hostjit_lib
+    PROPERTIES EXCLUDE_FROM_DEFAULT_BUILD_DEBUG TRUE
+  )
+endif()