#backends

Hostable JIT/AOT Library Survey for Mochi

§1 Provenance AsmJit : https://asmjit.com/ , https://github.com/asmjit Xbyak : https://github.com/herumi/xbyak Keystone : https://www.keystone-engine.org/ , https://github.com/keystone-engine/keystone (sibling of Capstone, https://www.capstone-engine.org/ ) Capstone : https://www.capstone-engine.org/ (disassembler, not codegen; relevant for round-trip testing) distorm3 : https://github.com/gdabah/distorm Iced (Rust/.NET) : https://github.com/icedland/iced Zydis : https://github.com/zyantific/zydis zasm : https://github.com/zyantific/zasm libgccjit : covered separately in 05_libgccjit.md . §2 Mechanism + §3 Target coverage + §4 Adoption + §5 Engineering cost (combined per library) AsmJit (C++, x86_64 /...

Emitting Object Files Directly for Mochi

§1 Provenance gimli (DWARF read/write, Rust): https://github.com/gimli-rs/gimli , https://crates.io/crates/gimli , current 0.31.1. object (ELF/Mach-O/COFF read/write, Rust): https://github.com/gimli-rs/object . ddbug (DWARF visualization): https://github.com/gimli-rs/ddbug . Go's debug/elf, debug/macho, debug/pe : https://pkg.go.dev/debug/elf , https://pkg.go.dev/debug/macho , https://pkg.go.dev/debug/pe (read-only in standard library). Go's debug/dwarf : https://pkg.go.dev/debug/dwarf (read-only). golang-asm objabi relocations : https://pkg.go.dev/github.com/twitchyliquid64/golang-asm@v0.15.1/objabi llvm-objdump , llvm-readelf , llvm-objcopy : standard LLVM utilities for round-trip inspection. System V ABI ELF spec : https://refspecs.linuxfoundation.org/elf/elf.pdf Mach-O reference (Apple) :...

MEP-42 Backend Survey: Summary and Recommendation

§1 What is in this directory This directory contains a per-backend evaluation for MEP-42: 01_llvm.md LLVM 20.x 02_cranelift.md Cranelift (Wasmtime) 03_qbe.md QBE 04_mir.md MIR (Vladimir Makarov) 05_libgccjit.md libgccjit 06_copy_and_patch.md copy-and-patch (CPython JIT) 07_dynasm.md DynASM (LuaJIT) 08_golang_asm.md golang-asm (already used by Mochi vm2jit) 09_mlir.md MLIR 10_c_as_backend.md C as a backend (Nim, V style) 11_tcc_chibicc.md TCC, chibicc, Cuik (reference points) 12_wasmtime_aot.md Wasmtime AOT 13_emitting_object_files.md Direct object file emission 14_jit_libraries_survey.md AsmJit, Xbyak, Keystone,...

Wasmtime AOT as a Code-Generation Backend for Mochi

§1 Provenance Project home: https://wasmtime.dev/ Source: https://github.com/bytecodealliance/wasmtime AOT docs: https://docs.wasmtime.dev/examples-pre-compiling-wasm.html CLI options: https://docs.wasmtime.dev/cli-options.html WASI Preview 2 launched (vote January 25, 2024): https://eunomia.dev/blog/2025/02/16/wasi-and-the-webassembly-component-model-current-status/ Bytecode Alliance blog: https://bytecodealliance.org/articles/ Wasmtime v25 release: WASI 0.2.1, user stack maps, extended consts. Wasmtime v27 release: completed Wasm GC, PyTorch wasi-nn backend. Wasmtime v35 release: AArch64 support in Winch, plus Component Model and Custom Page Sizes (per https://bytecodealliance.org/articles) . §2 Mechanism You bring a Wasm module. wasmtime...

TCC, chibicc, Cuik as Reference Points for Mochi

§1 Provenance TCC (Tiny C Compiler): https://bellard.org/tcc/ , mob branch at https://repo.or.cz/tinycc.git , mirror https://github.com/TinyCC/tinycc . Originally by Fabrice Bellard (~2001); since ~2012 maintained by grischka with community contributions through November 2025. Last official release: 0.9.27 (December 2017); the mob branch is the active line. chibicc : https://github.com/rui314/chibicc by Rui Ueyama (also author of LLVM lld and 8cc). Educational reference compiler for a book in progress. 8cc : https://github.com/rui314/8cc ,...

MLIR as a Code-Generation Backend for Mochi

§1 Provenance Project home: https://mlir.llvm.org/ Source: https://github.com/llvm/llvm-project/tree/main/mlir Users page: https://mlir.llvm.org/users/ Original paper: Chris Lattner et al., "MLIR: Scaling Compiler Infrastructure for Domain Specific Computation," CGO 2021. Mojo MLIR docs: https://docs.modular.com/mojo/notebooks/BoolMLIR/ Mojo vision: https://docs.modular.com/mojo/vision/ Awesome-MLIR/Mojo list: https://github.com/coderonion/awesome-mojo-max-mlir Mojo source-language Wikipedia: https://en.wikipedia.org/wiki/Mojo_(programming_language) Mojo HPC paper (SC25 workshops): https://arxiv.org/pdf/2509.21039 §2 Mechanism MLIR is an IR framework rather than a single IR. It provides: A common SSA infrastructure (Operations, Regions, Blocks, Values, Types, Attributes)....

C as a Code-Generation Backend for Mochi

§1 Provenance Nim's C backend: https://nim-lang.org/docs/backends.html Nim compiler user guide: https://nim-lang.org/docs/nimc.html Vlang (V): https://vlang.io/ ; the V compiler emits C by default. Hare uses QBE rather than C, so it is not an example here. Hare's c-cproc relative cproc is a C-to-QBE compiler. Cython: https://cython.org/ MicroPython's mpy-cross with C emission: https://github.com/micropython/micropython Classic reference: Cooper and Torczon, "Engineering a Compiler" (EaC), Chapters 7 and 8 cover C as a target. Earlier...

DynASM as a Code-Generation Backend for Mochi

§1 Provenance Project home: https://luajit.org/dynasm.html Features: https://luajit.org/dynasm_features.html Source in LuaJIT tree: https://github.com/LuaJIT/LuaJIT/tree/v2.1/dynasm ARM64 module: https://github.com/LuaJIT/LuaJIT/blob/v2.1/dynasm/dasm_arm64.lua Unofficial docs: https://corsix.github.io/dynasm-doc/ MoarVM fork: https://github.com/MoarVM/dynasm Author: Mike Pall (LuaJIT). Copyright 2005-2025 Mike Pall, MIT-licensed. Originally developed for LuaJIT 1, retained as a build-time tool for LuaJIT 2's hand-written interpreter. §2 Mechanism DynASM is a two-stage system: Preprocess time : a Lua script ( dynasm.lua ) reads a C source file with embedded | -prefixed...

Copy-and-Patch as a Code-Generation Backend for Mochi

§1 Provenance Original paper: Haoran Xu and Fredrik Kjolstad, "Copy-and-patch compilation: a fast compilation algorithm for high-level languages and bytecode," OOPSLA 2021 (PACMPL Vol. 5 Article 136). Note: the task brief said PLDI 2021; the paper is actually OOPSLA 2021. ACM: https://dl.acm.org/doi/10.1145/3485513 arXiv preprint: https://arxiv.org/abs/2011.13127 Author page (Fredrik Kjolstad): http://fredrikbk.com/copy-and-patch.html Stanford talk slides: https://aha.stanford.edu/sites/g/files/sbiybj20066/files/media/file/aha_050621_xu_copy-and-patch.pdf Wikipedia summary: https://en.wikipedia.org/wiki/Copy-and-patch PEP 744 (Python JIT): https://peps.python.org/pep-0744/ LWN follow-up (2025): https://lwn.net/Articles/1029307/ Real Python writeup: https://realpython.com/python313-free-threading-jit/...

golang-asm as a Code-Generation Backend for Mochi

§1 Provenance Repository: https://github.com/twitchyliquid64/golang-asm Package docs: https://pkg.go.dev/github.com/twitchyliquid64/golang-asm Latest tag: v0.15.1 (mirrors Go's cmd/internal/obj/* state at the corresponding upstream Go version). Upstream code lives in the official Go tree: https://go.googlesource.com/go/+/master/src/cmd/internal/obj/ Originally extracted by twitchyliquid64 (Tom Hennen) so that Wazero and similar Go-hosted projects could JIT Wasm without cgo. License: BSD-3-Clause (Go's license). §2 Mechanism The Go toolchain has its own assembler (Plan 9 lineage), used by cmd/asm and indirectly by cmd/compile...

libgccjit as a Code-Generation Backend for Mochi

§1 Provenance Documentation: https://gcc.gnu.org/onlinedocs/jit/ Source: in the GCC tree, https://gcc.gnu.org/git/?p=gcc.git;a=tree;f=gcc/jit Author: David Malcolm (Red Hat), with steady contributions from a Red Hat compiler team. Initial paper: David Malcolm, "libgccjit: An embeddable code-generation library backed by GCC," GCC Cauldron 2014 (slides at https://gcc.gnu.org/wiki/cauldron2014) . Emacs native compilation tracking: https://www.gnu.org/software/emacs/manual/html_node/elisp/Native_002dCompilation-Functions.html Andrea Corallo's gccemacs writeup: https://akrl.sdf.org/gccemacs.html §2 Mechanism libgccjit exposes a C API (with C++ and Python bindings) that lets callers build a...

QBE as a Code-Generation Backend for Mochi

§1 Provenance Project home: https://c9x.me/compile/ Source: https://c9x.me/git/qbe.git (mirror: https://github.com/8l/qbe ) Releases page: https://c9x.me/compile/release/ (current stable: qbe-1.2.tar.xz) Lobsters thread for QBE 1.0: https://lobste.rs/s/yqakzf/qbe_1_0 Mailing list: ~ mpu/qbe@lists.sr.ht (subscribe via sourcehut) Personal branch with extra patches: https://git.sr.ht/~mcf/qbe NLnet ARM32 grant (2025-10 start): https://nlnet.nl/project/QBE-32-bit-ARM-support/ Author: Quentin Carbonneaux (assistant professor at Yale, prior PhD work at Yale on cost-bounded program analysis). §1.5 Self-description (from project home) "QBE aims to provide 70% of the performance...

MIR as a Code-Generation Backend for Mochi

§1 Provenance Source: https://github.com/vnmakarov/mir Author blog: https://vnmakarov.github.io/ Releases: https://github.com/vnmakarov/mir/releases IR specification: https://github.com/vnmakarov/mir/blob/master/MIR.md C frontend (c2m): https://github.com/vnmakarov/mir/tree/master/c2mir Generator API: https://github.com/vnmakarov/mir/blob/master/mir-gen.h Author: Vladimir Makarov (formerly Red Hat, longtime GCC register allocator maintainer and RA designer of "IRA" in GCC). Project was originally a Ruby JIT experiment (the "Ruby MJIT replacement" discussion thread on the ruby-dev list), now a general-purpose backend. §2 Mechanism MIR is a "Medium Internal Representation": typed, three-address, but not...

LLVM as a Code-Generation Backend for Mochi

§1 Provenance Project home: https://llvm.org/ Source: https://github.com/llvm/llvm-project Release notes (current trunk): https://llvm.org/docs/ReleaseNotes.html LLVM 20.1.0 tagged March 10, 2025 (Fedora tracking: https://fedoraproject.org/wiki/Changes/LLVM-20 ) LLVM 20.X milestone tracker: https://github.com/llvm/llvm-project/milestone/26 Original paper: Chris Lattner and Vikram Adve, "LLVM: A Compilation Framework for Lifelong Program Analysis and Transformation," CGO 2004. Go bindings (community): https://github.com/tinygo-org/go-llvm Pure-Go IR builder (no cgo): https://github.com/llir/llvm §2 Mechanism LLVM consumes a typed, SSA, three-address intermediate representation (LLVM IR) and lowers...

Cranelift as a Code-Generation Backend for Mochi

§1 Provenance Project home: https://cranelift.dev/ Source: in the Wasmtime monorepo, https://github.com/bytecodealliance/wasmtime/tree/main/cranelift ISLE language reference: https://github.com/bytecodealliance/wasmtime/blob/main/cranelift/isle/docs/language-reference.md 2022 roadmap RFC (most recent formal): https://github.com/bytecodealliance/rfcs/blob/main/accepted/cranelift-roadmap-2022.md ISLE RFC: https://github.com/bytecodealliance/rfcs/blob/main/accepted/cranelift-isel-isle-peepmatic.md E-graph midend RFC: https://github.com/bytecodealliance/rfcs/blob/main/accepted/cranelift-egraph.md Wikipedia summary: https://en.wikipedia.org/wiki/Cranelift "Cranelift Progress in 2022": https://bytecodealliance.org/articles/cranelift-progress-2022 Bjorn3 progress reports (cg_clif): https://bjorn3.github.io/ §2 Mechanism Cranelift consumes CLIF, a target-independent SSA IR with block parameters (no phi nodes) and explicit memory operations. The pipeline is: legalization, an optional e-graph-based midend (constant...

Code Generation Backends