Write Solana BPF programs in Swift using upstream Rust toolchain, LLVM, and sbpf-linker.

• End-to-end Swift to BPF compilation pipeline driven with upstream toolings
• Custom LLVM pass to adapt Swift calling conventions and normalizes Swift literals
• Rust integration tests exercise the program under Mollusk SVM
• Direct Solana syscalls by hash with zero Solana SDK dependencies

1. Ensure prerequisites are installed (see below).
2. make build to emit LLVM IR, retarget for BPF, and link build/program.so.
3. make test to rebuild and run the Rust integration suite against Mollusk.
4. Inspect generated IR or artifacts under build/ as needed for debugging.

The toolchain expects a recent Swift compiler plus LLVM utilities (opt, llvm-as, llvm-config, clang++) and sbpf-linker.

# Fedora / RHEL example
sudo dnf install swift-lang llvm llvm-devel clang
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
cargo install sbpf-linker


# macOS example
brew install swift llvm
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
cargo install sbpf-linker

Ensure llvm-config is on PATH; override with LLVM_CONFIG=/path/to/bin/llvm-config if necessary. The build also uses clang++ to compile the custom LLVM pass.

1. swiftc emits optimized LLVM IR (build/entrypoint.ll) for src/entrypoint.swift.
2. The pass in tooling/llvm/swift_bpf_prepare_pass.cpp is built and run to pin literals and reset Swift calling conventions.
3. opt -mtriple=bpfel retargets the module for the Solana BPF ABI and llvm-as produces bitcode.
4. sbpf-linker --cpu v3 links the bitcode into build/program.so, suitable for deployment.

make

make test

• Install matching Swift and LLVM versions; stale toolchains often fail during IR emission
• If sbpf-linker cannot find LLVM libs, export LLVM_LIBDIR=/path/to/llvm/lib
• Re-run make clean when switching Swift toolchains to avoid stale IR
• Pass SWIFTC=/custom/swiftc or OPT=/custom/opt to make when using non-default binaries