Add experimental LLVM backend scaffolding

.github/workflows/main.yml

@@ -331,11 +331,98 @@ jobs:
       - name: Install CMake
         run: |
           apt-get install -y curl
-          curl -L https://github.com/Kitware/CMake/releases/download/v3.29.2/cmake-3.29.2-linux-x86_64.tar.gz | tar xz --strip-component 1 -C /usr/local/
+          curl -L https://github.com/Kitware/CMake/releases/download/v3.30.2/cmake-3.30.2-linux-x86_64.tar.gz | tar xz --strip-component 1 -C /usr/local/
       - run: cmake -G Ninja -B ./build
       - run: cmake --build ./build
       - run: ./build/bin/wasmkit --version
 
+  build-llvm-ubuntu:
+    strategy:
+      matrix:
+        include:
+          - os: ubuntu-24.04
+            llvm-target: X86
+          - os: ubuntu-24.04-arm
+            llvm-target: AArch64
+    runs-on: ${{ matrix.os }}
+    container:
+      image: swift:6.2-noble
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: apt-get update && apt-get install -y ninja-build python3
+      - name: Install CMake
+        run: |
+          apt-get install -y curl
+          if [[ "${{ matrix.llvm-target }}" == "AArch64" ]]; then
+            export CMAKE_ARCH=aarch64
+          elif [[ "${{ matrix.llvm-target }}" == "X86" ]]; then
+            export CMAKE_ARCH=x86_64
+          else
+            exit 1
+          fi
+
+          curl -L "https://github.com/Kitware/CMake/releases/download/v3.30.2/cmake-3.30.2-linux-${CMAKE_ARCH}.tar.gz" | tar xz --strip-component 1 -C /usr/local/
+      - name: Cache LLVM
+        id: cache-llvm
+        uses: actions/cache@v4
+        with:
+          path: ${{ github.workspace }}/Vendor/llvm-project
+          # IMPORTANT: Update the key when updating LLVM tag below in the build step.
+          key: llvm-${{ matrix.os }}-${{ matrix.llvm-target }}-swift-main-2026-01-04
+      - name: Build LLVM
+        if: steps.cache-llvm.outputs.cache-hit != 'true'
+        run: |
+          mkdir -p $GITHUB_WORKSPACE/Vendor/llvm-project
+          curl -L https://github.com/swiftlang/llvm-project/archive/refs/tags/swift-DEVELOPMENT-SNAPSHOT-2026-01-04-a.tar.gz | tar xz --strip-component 1 -C $GITHUB_WORKSPACE/Vendor/llvm-project
+          cmake -DLLVM_TARGETS_TO_BUILD=${{ matrix.llvm-target }} -DLLVM_INCLUDE_TESTS=OFF -DCMAKE_BUILD_TYPE=Release -G Ninja -S $GITHUB_WORKSPACE/Vendor/llvm-project/llvm -B $GITHUB_WORKSPACE/Vendor/llvm-project/llvm/build
+          cmake --build $GITHUB_WORKSPACE/Vendor/llvm-project/llvm/build
+      - name: Build WasmKit with LLVM
+        run: |
+          LLVM_DIR="$GITHUB_WORKSPACE/Vendor/llvm-project/llvm/build/lib/cmake/llvm/" cmake -DWASMKIT_BUILD_LLVM_BACKEND=ON -DWASMKIT_LLVM_BACKEND_TARGET=${{ matrix.llvm-target }} -DWASMKIT_BUILD_CLI=ON -G Ninja -B ./build
+          cmake --build ./build
+      - name: Run a smoke test
+        run: |
+          ./build/bin/wasmkit-llvm wat2wasm Examples/wasm/factorial.wat
+          ./build/bin/wasmkit-llvm run Examples/wasm/factorial.wasm fac i64:5
+
+  build-llvm-macos:
+    strategy:
+      matrix:
+        include:
+          - os: macos-26
+            llvm-target: AArch64
+
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Cache LLVM
+        id: cache-llvm
+        uses: actions/cache@v4
+        with:
+          path: ${{ github.workspace }}/Vendor/llvm-project
+          # IMPORTANT: Update the key when updating LLVM tag below in the build step.
+          key: llvm-${{ matrix.os }}-${{ matrix.llvm-target }}-swift-main-2026-01-04
+      - name: Build LLVM
+        if: steps.cache-llvm.outputs.cache-hit != 'true'
+        run: |
+          sudo xcode-select -s /Applications/Xcode_26.2.app
+          mkdir -p $GITHUB_WORKSPACE/Vendor/llvm-project
+          curl -L https://github.com/swiftlang/llvm-project/archive/refs/tags/swift-DEVELOPMENT-SNAPSHOT-2026-01-04-a.tar.gz | tar xz --strip-component 1 -C $GITHUB_WORKSPACE/Vendor/llvm-project
+          cmake -DLLVM_TARGETS_TO_BUILD=${{ matrix.llvm-target }} -DLLVM_INCLUDE_TESTS=OFF -DCMAKE_BUILD_TYPE=Release -G Ninja -S $GITHUB_WORKSPACE/Vendor/llvm-project/llvm -B $GITHUB_WORKSPACE/Vendor/llvm-project/llvm/build
+          cmake --build $GITHUB_WORKSPACE/Vendor/llvm-project/llvm/build
+      - name: Build WasmKit with LLVM
+        run: |
+          LLVM_DIR="$GITHUB_WORKSPACE/Vendor/llvm-project/llvm/build/lib/cmake/llvm/" cmake -DWASMKIT_BUILD_LLVM_BACKEND=ON -DWASMKIT_LLVM_BACKEND_TARGET=${{ matrix.llvm-target }} -DWASMKIT_BUILD_CLI=ON -G Ninja -B ./build
+          cmake --build ./build
+      - name: Run a smoke test
+        run: |
+          ./build/bin/wasmkit-llvm wat2wasm Examples/wasm/factorial.wat
+          ./build/bin/wasmkit-llvm run Examples/wasm/factorial.wasm fac i64:5
+
   build-wasi:
     runs-on: ubuntu-24.04
     container:

CMakeLists.txt

@@ -1,26 +1,28 @@
-cmake_minimum_required(VERSION 3.19.6)
+cmake_minimum_required(VERSION 3.30)
 
 list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules)
 
-project(WasmKit LANGUAGES C Swift)
+project(WasmKit LANGUAGES C CXX Swift)
 
-set(SWIFT_VERSION 5)
+set(SWIFT_VERSION 6)
 set(CMAKE_Swift_LANGUAGE_VERSION ${SWIFT_VERSION})
 
+set(min_supported_swift_version 6.2)
+if(CMAKE_Swift_COMPILER_VERSION VERSION_LESS "${min_supported_swift_version}")
+  message(
+    FATAL_ERROR
+    "Outdated Swift compiler: "
+    "Swift ${min_supported_swift_version} or newer is required."
+  )
+endif()
+
 # Enable whole module optimization for Release or RelWithDebInfo builds.
 if(POLICY CMP0157)
   set(CMAKE_Swift_COMPILATION_MODE $<IF:$<CONFIG:Release,RelWithDebInfo>,wholemodule,incremental>)
 else()
   add_compile_options($<$<AND:$<COMPILE_LANGUAGE:Swift>,$<CONFIG:Release,RelWithDebInfo>>:-wmo>)
 endif()
 
-if(CMAKE_VERSION VERSION_LESS 3.21)
-  get_property(parent_dir DIRECTORY PROPERTY PARENT_DIRECTORY)
-  if(NOT parent_dir)
-    set(PROJECT_IS_TOP_LEVEL TRUE)
-  endif()
-endif()
-
 # The subdirectory into which host libraries will be installed.
 set(SWIFT_HOST_LIBRARIES_SUBDIRECTORY "swift/host")
 
@@ -52,7 +54,9 @@ add_compile_definitions(
 
 include(FetchContent)
 
-option(WASMKIT_BUILD_CLI "Build wasmkit-cli" ON)
+option(WASMKIT_BUILD_CLI "Build WasmKit CLI" ON)
+option(WASMKIT_BUILD_LLVM_BACKEND "Build WasmKit LLVM backend (experimental)" OFF)
+option(WASMKIT_LLVM_BACKEND_TARGET "WasmKit LLVM backend target architecture" "aarch64")
 
 if(WASMKIT_BUILD_CLI)
   set(BUILD_TESTING OFF) # disable ArgumentParser tests
@@ -67,6 +71,43 @@ if(WASMKIT_BUILD_CLI)
   endif()
 endif()
 
+if(WASMKIT_BUILD_LLVM_BACKEND)
+  FetchContent_Declare(
+    SwiftLLVMBindings
+    GIT_REPOSITORY "https://github.com/swiftlang/swift-llvm-bindings.git"
+    GIT_TAG c1fffb92d4f9d7cb98800762631cfa354869fb46
+    GIT_SHALLOW TRUE
+    GIT_PROGRESS ON
+  )
+
+  FetchContent_MakeAvailable(SwiftLLVMBindings)
+
+  find_package(Subprocess CONFIG)
+
+  if(NOT Subprocess_FOUND)
+    message("-- Vending Subprocess")
+    FetchContent_Declare(
+      Subprocess
+      GIT_REPOSITORY https://github.com/swiftlang/swift-subprocess
+      GIT_TAG 0.2.1
+      GIT_SHALLOW TRUE
+    )
+    FetchContent_MakeAvailable(Subprocess)
+  endif()
+
+  find_package(SwiftCollections CONFIG)
+  if(NOT SwiftCollections_FOUND)
+    message("-- Vending SwiftCollections")
+    FetchContent_Declare(
+      SwiftCollections
+      GIT_REPOSITORY https://github.com/apple/swift-collections
+      GIT_TAG 1.3.0
+      GIT_SHALLOW TRUE
+    )
+    FetchContent_MakeAvailable(SwiftCollections)
+  endif()
+endif()
+
 find_package(SwiftSystem CONFIG)
 if(NOT SwiftSystem_FOUND)
   message("-- Vending SwiftSystem")

Sources/CLICommands/CMakeLists.txt

@@ -5,16 +5,4 @@ add_wasmkit_library(CLICommands
 )
 
 target_link_wasmkit_libraries(CLICommands PUBLIC
-  WAT WasmKitWASI)
-
-add_dependencies(
-  CLICommands
-
-  ArgumentParser
-)
-
-target_link_libraries(CLICommands
-
-  PUBLIC
-  ArgumentParser
-)
+  ArgumentParser WAT WasmKitWASI)

Sources/CMakeLists.txt

@@ -11,3 +11,12 @@ if(WASMKIT_BUILD_CLI)
   add_subdirectory(CLI)
   add_subdirectory(CLICommands)
 endif()
+
+if(WASMKIT_BUILD_LLVM_BACKEND)
+  add_subdirectory(LLVMInterop)
+  add_subdirectory(LLVMBackend)
+
+  if(WASMKIT_BUILD_CLI)
+    add_subdirectory(LLVMBackendCLI)
+  endif()
+endif()

Sources/LLVMBackend/CMakeLists.txt

@@ -0,0 +1,42 @@
+add_library(
+  LLVMBackend
+
+  CodegenContext.swift
+  IRContext+codegen.swift
+  IRFunctionVisitor.swift
+  Linker.swift
+  Loader.swift
+  Wasm32Memory.swift
+)
+target_compile_options(
+  LLVMBackend
+  PUBLIC
+    "SHELL:-Xcc -std=c++17"
+    "SHELL:-Xcc -fapinotes"
+    "SHELL:-Xcc -fapinotes-modules"
+    "-cxx-interoperability-mode=default"
+    -package-name WasmKitPackage
+)
+
+target_include_directories(
+  LLVMBackend
+  PUBLIC
+    "${LLVMINTEROP_INCLUDE_DIR}"
+    "${LLVM_MAIN_INCLUDE_DIR}"
+    "${LLVM_INCLUDE_DIR}"
+)
+
+set(WASMKIT_DEPENDENCIES WAT WasmKit WasmTypes WasmParser)
+set(BUILD_TESTING OFF)
+
+add_dependencies(LLVMInterop BasicContainers LLVM_Utils Subprocess ${WASMKIT_DEPENDENCIES})
+
+target_link_libraries(
+  LLVMBackend
+
+  BasicContainers
+  ${WASMKIT_DEPENDENCIES}
+  LLVMInterop
+  LLVM_Utils
+  Subprocess
+)