Crate atomic_maybe_uninit

source ·
Expand description

Atomic operations on potentially uninitialized integers.

Motivation

Copying types containing uninitialized bytes (e.g., padding), via the standard library’s atomic types is undefined behavior because the copy goes through integers.

This crate provides a way to soundly perform such operations.

Platform Support

Currently, x86, x86_64, ARM (v6+), AArch64, RISC-V, MIPS32r2, MIPS64r2, PowerPC, s390x, and MSP430 are supported.

target_archprimitivesload/storeswapCAS
x86isize,usize,i8,u8,i16,u16,i32,u32,i64,u64✓✓✓
x86_64isize,usize,i8,u8,i16,u16,i32,u32,i64,u64✓✓✓
x86_64 (+cmpxchg16b)i128,u128✓✓✓
arm (v6+)isize,usize,i8,u8,i16,u16,i32,u32✓✓[1]✓[1]
arm (v6 except v6-m, v7-a+) [2]i64,u64✓✓✓
aarch64isize,usize,i8,u8,i16,u16,i32,u32,i64,u64,i128,u128✓✓✓
riscv32isize,usize,i8,u8,i16,u16,i32,u32✓✓[1]✓[1]
riscv64isize,usize,i8,u8,i16,u16,i32,u32,i64,u64✓✓[1]✓[1]
mips [3]isize,usize,i8,u8,i16,u16,i32,u32✓✓✓
mips64 [3]isize,usize,i8,u8,i16,u16,i32,u32,i64,u64✓✓✓
powerpc [3]isize,usize,i8,u8,i16,u16,i32,u32✓✓✓
powerpc64 [3]isize,usize,i8,u8,i16,u16,i32,u32,i64,u64✓✓✓
powerpc64 (pwr8+) [3] [4]i128,u128✓✓✓
s390x [3]isize,usize,i8,u8,i16,u16,i32,u32,i64,u64,i128,u128✓✓✓
msp430 [3]isize,usize,i8,u8,i16,u16✓

[1] ARM’s atomic RMW operations are not available on v6-m (thumbv6m). RISC-V’s atomic RMW operations are not available on targets without the A (or G which means IMAFD) extension such as riscv32i, riscv32imc, etc.
[2] ARMv6 except ARMv6-M, ARMv7+ with A-profile
[3] Requires nightly due to #![feature(asm_experimental_arch)].
[4] target-cpu pwr8, pwr9, or pwr10. powerpc64le is pwr8 by default.

Feel free to submit an issue if your target is not supported yet.

Modules

raw
Low level API.

Structs

AtomicMaybeUninit
A potentially uninitialized integer type which can be safely shared between threads.