GoKawiilRust 1.87 lets compiler verify SIMD safety, removing need for manual unsafe blocks
Rust's SIMD abstractions previously required wrapping raw intrinsic calls in unsafe blocks because the compiler couldn't verify at compile time whether the CPU running the code actually supported the needed instruction set. As of Rust 1.87, the compiler itself tracks which instruction sets are available, letting developers call SIMD intrinsics without manually marking them unsafe or writing complex cross-referencing logic.
GoKawiil's interpretation of the reporting above, not reported fact.
This closes a long-standing safety gap where high-level SIMD abstractions looked clean on the surface but hid large amounts of unsafe code underneath, which the author says was error-prone and hard to verify by hand. By moving instruction-set verification into the compiler, Rust could make numerically intensive code using SIMD both easier to write and less prone to undefined behavior from mismatched CPU features.
- Rust 1.87 introduced compiler-level tracking of available CPU instruction sets for SIMD calls.
- Previously, developers had to manually wrap SIMD intrinsic calls in unsafe blocks and verify feature availability themselves.
- The change aims to eliminate hidden unsafe code inside Rust's SIMD abstraction libraries.
Source: shnatsel.github.io, 2026-10-10
Published there as: “Safe SIMD in Rust, even on the inside”
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