Cranelift (formerly known as Cretonne) is an optimizing compiler backend that converts a target-independent intermediate representation into executable machine code. It is written in Rust. The project started in 2016 and is currently developed by Bytecode Alliance.[2][3] Unlike compiler backends such as LLVM that focus more on ahead-of-time compilation, Cranelift instead focuses on just-in-time compilation with short compile time being an explicit goal of the project.[4]

Cranelift
Developer(s)Bytecode Alliance
Initial release2016; 8 years ago (2016)
Stable release
0.105.2 / February 28, 2024; 8 months ago (2024-02-28)
Written inRust
Operating systemCross-platform
TypeCompiler
LicenseApache License with LLVM exceptions[1]
Websitecranelift.dev

As of 2023, Cranelift supports instruction set architectures such as x86-64, AArch64, RISC-V, and IBM z/Architecture.

History

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Prior to the backend framework rewrite in 2020, the project made use of only one intermediate representation (IR) across all compilation stages prior to machine code emission, namely CLIF (Cranelift IR Format). The old design made use of instruction legalizations, which involved transforming the high-level IR continuously until each CLIF instruction corresponded to an instruction of the target machine, at which point the executable code could be emitted.

In 2020, the backend was rewritten to use a separate, machine-specific IR called VCode for later compilation stages instead. After this rewrite, a high-level input CLIF would be optimized by a middle layer before being lowered into VCode, which would be further transformed by remaining passes in the backend.[4] Peepmatic, a tool used to generate a peephole optimizer from a domain-specific language (DSL), was also added,[5] though it was later removed.[6]

In 2022, a new register allocator, which was adapted from the register allocator from IonMonkey, was added. In addition, the backend framework was reworked to utilize ISLE (Instruction Selection/Lowering Expressions DSL), another DSL in the project that was made to ease the development of the instruction selection stage in backends.[7]

The mid-end saw addition of optimization passes that make use of e-graphs in 2022.[8] The optimization passes are enabled by default starting in 2023.

Applications

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Currently, Cranelift is being utilized by multiple WebAssembly runtimes, such as Wasmtime  and Wasmer , with performance comparable to LLVM-based runtimes.[9]

An alternative code generator for the Rust compiler that is powered by Cranelift also exists.[10]

See also

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References

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  1. ^ "LICENSE.md". GitHub.
  2. ^ "GitHub - bytecodealliance/cranelift at 399be07fcf00d0974d2a83d1af55f0bee9861d54". GitHub. Retrieved 26 January 2023.
  3. ^ "wasmtime/cranelift at main · bytecodealliance/wasmtime". GitHub. Retrieved 26 January 2023.
  4. ^ a b Fallin, Chris. "A New Backend for Cranelift, Part 1: Instruction Selection". cfallin.org. Retrieved 26 January 2023.
  5. ^ "Introduce peepmatic: a peephole optimizations DSL and peephole optimizer compiler by fitzgen · Pull Request #1647 · bytecodealliance/wasmtime". GitHub.
  6. ^ "Remove Peepmatic!!! by fitzgen · Pull Request #3543 · bytecodealliance/wasmtime". GitHub. Retrieved 2023-02-03.
  7. ^ Fallin, Chris. "Cranelift's Instruction Selector DSL, ISLE: Term-Rewriting Made Practical". cfallin.org. Retrieved 26 January 2023.
  8. ^ "egraph-based midend: draw the rest of the owl (productionized). by cfallin · Pull Request #4953 · bytecodealliance/wasmtime". GitHub. Retrieved 26 January 2023.
  9. ^ Denis, Frank. "Performance of WebAssembly runtimes in 2023 | Frank DENIS random thoughts". 00f.net. Retrieved 26 January 2023.
  10. ^ "Cranelift codegen backend for rust". GitHub. 26 January 2023. Retrieved 26 January 2023.