fix: Make LLVM optional on Windows

- Official LLVM Windows installers don't include CMake config files
- Make LLVM optional on Windows, required on Unix
-  Set LLVM_AVAILABLE flag to track whether LLVM is found
- Add USE_LLVM_BACKEND compilation flag when LLVM is available
- Conditionally compile LLVM-dependent code
- Build succeeds without LLVM on Windows

Windows builds will work without LLVM backend optimization.
Unix builds still require LLVM for full functionality.

Author: ProgrammerKR

.github/workflows/build.yml

@@ -77,22 +77,22 @@ jobs:
             Add-Content $env:GITHUB_PATH "$llvmRoot/bin"
             Add-Content $env:GITHUB_ENV "LLVM_DIR=$llvmDir"
             Add-Content $env:GITHUB_ENV "LLVM_ROOT=$llvmRoot"
+            Add-Content $env:GITHUB_ENV "LLVM_AVAILABLE=1"
             
             Write-Host "✓ LLVM installed at: $llvmRoot"
             Write-Host "✓ LLVM_DIR set to: $llvmDir"
           } else {
-            Write-Host "✗ Could not find LLVMConfig.cmake after installation"
-            Write-Host "Listing LLVM directory structure..."
-            Get-ChildItem -Path $llvmRoot -Recurse -Directory | Select-Object -First 20 | ForEach-Object { Write-Host $_.FullName }
-            exit 1
+            Write-Host "✗ LLVMConfig.cmake not found - LLVM backend will be disabled"
+            Write-Host "Building without LLVM support on Windows"
+            Add-Content $env:GITHUB_ENV "LLVM_AVAILABLE=0"
           }
 
       - name: Install Ninja (Windows)
         if: matrix.os == 'windows-latest'
         run: choco install ninja -y
 
       - name: Debug LLVM Configuration (Windows)
-        if: matrix.os == 'windows-latest'
+        if: matrix.os == 'windows-latest' && env.LLVM_AVAILABLE == '1'
         shell: pwsh
         run: |
           Write-Host "LLVM_DIR: $env:LLVM_DIR"

CMakeLists.txt

@@ -47,17 +47,28 @@ if(WIN32)
 endif()
 
 # --- LLVM Configuration ---
-find_package(LLVM CONFIG REQUIRED)
+if(WIN32)
+    # Try to find LLVM, but don't require it on Windows
+    find_package(LLVM CONFIG QUIET)
+else()
+    # LLVM is required on Unix platforms
+    find_package(LLVM CONFIG REQUIRED)
+endif()
 
 if(NOT LLVM_FOUND)
-    message(FATAL_ERROR "LLVM not found! Please install LLVM and set LLVM_DIR.")
+    if(WIN32)
+        message(WARNING "LLVM not found. Building without LLVM backend support on Windows.")
+    else()
+        message(FATAL_ERROR "LLVM not found! Please install LLVM and set LLVM_DIR.")
+    endif()
+else()
+    message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")
+    message(STATUS "LLVM Include Dirs: ${LLVM_INCLUDE_DIRS}")
+    message(STATUS "LLVM Library Dirs: ${LLVM_LIBRARY_DIRS}")
+    message(STATUS "LLVM Definitions: ${LLVM_DEFINITIONS}")
+    add_definitions(-DUSE_LLVM_BACKEND)
 endif()
 
-message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")
-message(STATUS "LLVM Include Dirs: ${LLVM_INCLUDE_DIRS}")
-message(STATUS "LLVM Library Dirs: ${LLVM_LIBRARY_DIRS}")
-message(STATUS "LLVM Definitions: ${LLVM_DEFINITIONS}")
-
 # --- LibFFI Configuration ---
 # specialized find_package might be needed if not in standard path, but let's try standard first
 find_package(PkgConfig QUIET)
@@ -82,19 +93,21 @@ else()
     message(WARNING "LibFFI not found. FFI features will be disabled.")
 endif()
 
-include_directories(SYSTEM ${LLVM_INCLUDE_DIRS})
-add_definitions(${LLVM_DEFINITIONS})
+if(LLVM_FOUND)
+    include_directories(SYSTEM ${LLVM_INCLUDE_DIRS})
+    add_definitions(${LLVM_DEFINITIONS})
 
-# Explicitly add LLVM library directories
-link_directories(${LLVM_LIBRARY_DIRS})
-
-if(WIN32)
-    # Additional linking configuration for Windows
+    # Explicitly add LLVM library directories
     link_directories(${LLVM_LIBRARY_DIRS})
-endif()
 
-# Map generic components to specific libs
-llvm_map_components_to_libnames(llvm_libs core support executionengine native ipo analysis transformutils bitwriter)
+    if(WIN32)
+        # Additional linking configuration for Windows
+        link_directories(${LLVM_LIBRARY_DIRS})
+    endif()
+
+    # Map generic components to specific libs
+    llvm_map_components_to_libnames(llvm_libs core support executionengine native ipo analysis transformutils bitwriter)
+endif()
 
 # Export symbols for Windows DLL
 set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON)