LLVM Gains an x86 Target for the Lightweight Fault Isolation Sandbox

The LLVM project has gained x86 and x86_64 support for Lightweight Fault Isolation (LFI) — a mechanism for isolating code at the process level. The corresponding target was officially merged upstream this week.

LFI is being developed by researchers at Stanford University. The technology is implemented as a set of compiler passes and target architectures for LLVM, and it is designed to provide an efficient software sandbox that allows untrusted native code to be executed in an isolated form within a single process.

Before the arrival of the x86 target, an LFI implementation for the AArch64 architecture had already been added to LLVM. As a result, x86/x86_64 has become the second platform to receive official support for this technology in the compiler's main codebase.

LFI is positioned as a lightweight alternative to traditional isolation methods such as separate processes or virtual machines, since it does not require context switching or the associated overhead. This makes the technology potentially useful in scenarios where performance matters when working with untrusted code — for example, for plugins, WebAssembly-like runtimes, or kernel modules.

The inclusion of the LFI x86 target in upstream LLVM opens up the possibility for developers to use this technology on the most widespread hardware platform without having to maintain third-party patches or compiler forks.

Source: Phoronix