Cross-platform CI (Linux x64/ARM, macOS, Windows)

[AveryClapp]

Feature Description

Expand CI to test on all major platforms and architectures.

Current State

• Only tested locally on macOS ARM64

Target Platforms

• macOS ARM64 (developer machine)
• macOS x64 (Intel Macs)
• Linux x64 (Ubuntu 22.04, 24.04)
• Linux ARM64 (AWS Graviton, Raspberry Pi)
• Windows x64 (MSVC, MinGW, WSL)

GitHub Actions Matrix

strategy:
  matrix:
    os: [ubuntu-22.04, ubuntu-24.04, macos-13, macos-14, windows-2022]
    llvm: [17, 18, 19, 20, 21]

Platform-Specific Issues

• Windows: Path separators, LLVM installation
• Linux ARM: QEMU emulation (slow)
• macOS Intel: Homebrew LLVM paths

Implementation

• Update CMakeLists.txt for Windows
• CI workflow for all platforms
• Pre-built LLVM passes for each platform
• Platform-specific documentation

Files

• .github/workflows/ci.yml (extend)
• backend/llvm-pass/CMakeLists.txt (Windows fixes)
• docs/building-windows.md (new)

Acceptance Criteria

• All tests pass on all platforms
• Pre-built binaries for each platform in releases
• Platform badges in README