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Jubilee Young
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Arm's FEAT_FP and Feat_AdvSIMD describe the same thing on AArch64: The Neon unit, which handles both floating point and SIMD instructions. Moreover, a configuration for AArch64 must include both or neither. Arm says "entirely proprietary" toolchains may omit floating point: https://developer.arm.com/documentation/102374/0101/Data-processing---floating-point In the Programmer's Guide for Armv8-A, Arm says AArch64 can have both FP and Neon or neither in custom implementations: https://developer.arm.com/documentation/den0024/a/AArch64-Floating-point-and-NEON In "Bare metal boot code for Armv8-A", enabling Neon and FP is just disabling the same trap flag: https://developer.arm.com/documentation/dai0527/a In an unlikely future where "Neon and FP" become unrelated, we can add "[+-]fp" as its own feature flag. Until then, we can simplify programming with Rust on AArch64 by folding both into "[+-]neon", which is valid as it supersets both. "[+-]neon" is retained for niche uses such as firmware, kernels, "I just hate floats", and so on.
This directory contains the source code of the rust project, including:
- The test suite
- The bootstrapping build system
- Various submodules for tools, like rustdoc, rls, etc.
For more information on how various parts of the compiler work, see the rustc dev guide.