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SipHasher128: use specific struct layout

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Tyson Nottingham 2020-10-05 00:47:44 -07:00
parent b86161ad9c
commit 581cc4abf5
1 changed files with 6 additions and 0 deletions
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6
compiler/rustc_data_structures/src/sip128.rs
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@ -15,7 +15,13 @@ const BUFFER_SIZE_BYTES_SPILL: usize = BUFFER_SIZE_ELEMS_SPILL * ELEM_SIZE;
const BUFFER_SPILL_INDEX: usize = BUFFER_SIZE_ELEMS_SPILL - 1; const BUFFER_SPILL_INDEX: usize = BUFFER_SIZE_ELEMS_SPILL - 1;
#[derive(Debug, Clone)] #[derive(Debug, Clone)]
#[repr(C)]
pub struct SipHasher128 { pub struct SipHasher128 {
// The access pattern during hashing consists of accesses to `nbuf` and
// `buf` until the buffer is full, followed by accesses to `state` and
// `processed`, and then repetition of that pattern until hashing is done.
// This is the basis for the ordering of fields below. However, in practice
// the cache miss-rate for data access is extremely low regardless of order.
nbuf: usize, // how many bytes in buf are valid nbuf: usize, // how many bytes in buf are valid
buf: [MaybeUninit<u64>; BUFFER_SIZE_ELEMS_SPILL], // unprocessed bytes le buf: [MaybeUninit<u64>; BUFFER_SIZE_ELEMS_SPILL], // unprocessed bytes le
state: State, // hash State state: State, // hash State