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Increase 64-bit rotation from 20 to 26 bits on finalizer #56

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Merged
merged 1 commit into from
Feb 5, 2025
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Increase 64-bit rotation from 20 to 26 bits on finalizer #56

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2 changes: 1 addition & 1 deletion Cargo.toml
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
[package]
name = "rustc-hash"
version = "2.1.0"
version = "2.1.1"
authors = ["The Rust Project Developers"]
description = "A speedy, non-cryptographic hashing algorithm used by rustc"
license = "Apache-2.0 OR MIT"
Expand Down
104 changes: 52 additions & 52 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -170,12 +170,12 @@ impl Hasher for FxHasher {
// As most hash table implementations (including hashbrown) compute
// the bucket index from the bottom bits we want to move bits from the
// top to the bottom. Ideally we'd rotate left by exactly the hash table
// size, but as we don't know this we'll choose 20 bits, giving decent
// entropy up until 2^20 table sizes. On 32-bit hosts we'll dial it
// size, but as we don't know this we'll choose 26 bits, giving decent
// entropy up until 2^26 table sizes. On 32-bit hosts we'll dial it
// back down a bit to 15 bits.

#[cfg(target_pointer_width = "64")]
const ROTATE: u32 = 20;
const ROTATE: u32 = 26;
#[cfg(target_pointer_width = "32")]
const ROTATE: u32 = 15;

Expand Down Expand Up @@ -339,75 +339,75 @@ mod tests {
fn unsigned() {
test_hash! {
hash(0_u8) == 0,
hash(1_u8) == if B32 { 3001993707 } else { 12583873379513078615 },
hash(100_u8) == if B32 { 3844759569 } else { 4008740938959785536 },
hash(u8::MAX) == if B32 { 999399879 } else { 17600987023830959190 },
hash(1_u8) == if B32 { 3001993707 } else { 12157901119326311915 },
hash(100_u8) == if B32 { 3844759569 } else { 16751747135202103309 },
hash(u8::MAX) == if B32 { 999399879 } else { 1211781028898739645 },

hash(0_u16) == 0,
hash(1_u16) == if B32 { 3001993707 } else { 12583873379513078615 },
hash(100_u16) == if B32 { 3844759569 } else { 4008740938959785536 },
hash(u16::MAX) == if B32 { 3440503042 } else { 4001367065645062987 },
hash(1_u16) == if B32 { 3001993707 } else { 12157901119326311915 },
hash(100_u16) == if B32 { 3844759569 } else { 16751747135202103309 },
hash(u16::MAX) == if B32 { 3440503042 } else { 16279819243059860173 },

hash(0_u32) == 0,
hash(1_u32) == if B32 { 3001993707 } else { 12583873379513078615 },
hash(100_u32) == if B32 { 3844759569 } else { 4008740938959785536 },
hash(u32::MAX) == if B32 { 1293006356 } else { 17126373362251322066 },
hash(1_u32) == if B32 { 3001993707 } else { 12157901119326311915 },
hash(100_u32) == if B32 { 3844759569 } else { 16751747135202103309 },
hash(u32::MAX) == if B32 { 1293006356 } else { 7729994835221066939 },

hash(0_u64) == 0,
hash(1_u64) == if B32 { 275023839 } else { 12583873379513078615 },
hash(100_u64) == if B32 { 1732383522 } else { 4008740938959785536 },
hash(u64::MAX) == if B32 { 1017982517 } else { 5862870694197521576 },
hash(1_u64) == if B32 { 275023839 } else { 12157901119326311915 },
hash(100_u64) == if B32 { 1732383522 } else { 16751747135202103309 },
hash(u64::MAX) == if B32 { 1017982517 } else { 6288842954450348564 },

hash(0_u128) == 0,
hash(1_u128) == if B32 { 1860738631 } else { 12885773367358079611 },
hash(100_u128) == if B32 { 1389515751 } else { 15751995649841559633 },
hash(u128::MAX) == if B32 { 2156022013 } else { 11423841400550042156 },
hash(1_u128) == if B32 { 1860738631 } else { 13032756267696824044 },
hash(100_u128) == if B32 { 1389515751 } else { 12003541609544029302 },
hash(u128::MAX) == if B32 { 2156022013 } else { 11702830760530184999 },

hash(0_usize) == 0,
hash(1_usize) == if B32 { 3001993707 } else { 12583873379513078615 },
hash(100_usize) == if B32 { 3844759569 } else { 4008740938959785536 },
hash(usize::MAX) == if B32 { 1293006356 } else { 5862870694197521576 },
hash(1_usize) == if B32 { 3001993707 } else { 12157901119326311915 },
hash(100_usize) == if B32 { 3844759569 } else { 16751747135202103309 },
hash(usize::MAX) == if B32 { 1293006356 } else { 6288842954450348564 },
}
}

#[test]
fn signed() {
test_hash! {
hash(i8::MIN) == if B32 { 2000713177 } else { 5869058164817243095 },
hash(i8::MIN) == if B32 { 2000713177 } else { 6684841074112525780 },
hash(0_i8) == 0,
hash(1_i8) == if B32 { 3001993707 } else { 12583873379513078615 },
hash(100_i8) == if B32 { 3844759569 } else { 4008740938959785536 },
hash(i8::MAX) == if B32 { 3293686765 } else { 11731928859014764671 },
hash(1_i8) == if B32 { 3001993707 } else { 12157901119326311915 },
hash(100_i8) == if B32 { 3844759569 } else { 16751747135202103309 },
hash(i8::MAX) == if B32 { 3293686765 } else { 12973684028562874344 },

hash(i16::MIN) == if B32 { 1073764727 } else { 8292620222579070801 },
hash(i16::MIN) == if B32 { 1073764727 } else { 14218860181193086044 },
hash(0_i16) == 0,
hash(1_i16) == if B32 { 3001993707 } else { 12583873379513078615 },
hash(100_i16) == if B32 { 3844759569 } else { 4008740938959785536 },
hash(i16::MAX) == if B32 { 2366738315 } else { 14155490916776592377 },
hash(1_i16) == if B32 { 3001993707 } else { 12157901119326311915 },
hash(100_i16) == if B32 { 3844759569 } else { 16751747135202103309 },
hash(i16::MAX) == if B32 { 2366738315 } else { 2060959061933882993 },

hash(i32::MIN) == if B32 { 16384 } else { 5631751334026900245 },
hash(i32::MIN) == if B32 { 16384 } else { 9943947977240134995 },
hash(0_i32) == 0,
hash(1_i32) == if B32 { 3001993707 } else { 12583873379513078615 },
hash(100_i32) == if B32 { 3844759569 } else { 4008740938959785536 },
hash(i32::MAX) == if B32 { 1293022740 } else { 11494622028224421821 },
hash(1_i32) == if B32 { 3001993707 } else { 12157901119326311915 },
hash(100_i32) == if B32 { 3844759569 } else { 16751747135202103309 },
hash(i32::MAX) == if B32 { 1293022740 } else { 16232790931690483559 },

hash(i64::MIN) == if B32 { 16384 } else { 524288 },
hash(i64::MIN) == if B32 { 16384 } else { 33554432 },
hash(0_i64) == 0,
hash(1_i64) == if B32 { 275023839 } else { 12583873379513078615 },
hash(100_i64) == if B32 { 1732383522 } else { 4008740938959785536 },
hash(i64::MAX) == if B32 { 1017998901 } else { 5862870694198045864 },
hash(1_i64) == if B32 { 275023839 } else { 12157901119326311915 },
hash(100_i64) == if B32 { 1732383522 } else { 16751747135202103309 },
hash(i64::MAX) == if B32 { 1017998901 } else { 6288842954483902996 },

hash(i128::MIN) == if B32 { 16384 } else { 524288 },
hash(i128::MIN) == if B32 { 16384 } else { 33554432 },
hash(0_i128) == 0,
hash(1_i128) == if B32 { 1860738631 } else { 12885773367358079611 },
hash(100_i128) == if B32 { 1389515751 } else { 15751995649841559633 },
hash(i128::MAX) == if B32 { 2156005629 } else { 11423841400549517868 },
hash(1_i128) == if B32 { 1860738631 } else { 13032756267696824044 },
hash(100_i128) == if B32 { 1389515751 } else { 12003541609544029302 },
hash(i128::MAX) == if B32 { 2156005629 } else { 11702830760496630567 },

hash(isize::MIN) == if B32 { 16384 } else { 524288 },
hash(isize::MIN) == if B32 { 16384 } else { 33554432 },
hash(0_isize) == 0,
hash(1_isize) == if B32 { 3001993707 } else { 12583873379513078615 },
hash(100_isize) == if B32 { 3844759569 } else { 4008740938959785536 },
hash(isize::MAX) == if B32 { 1293022740 } else { 5862870694198045864 },
hash(1_isize) == if B32 { 3001993707 } else { 12157901119326311915 },
hash(100_isize) == if B32 { 3844759569 } else { 16751747135202103309 },
hash(isize::MAX) == if B32 { 1293022740 } else { 6288842954483902996 },
}
}

Expand All @@ -422,13 +422,13 @@ mod tests {
#[test]
fn bytes() {
test_hash! {
hash(HashBytes(&[])) == if B32 { 2673204745 } else { 5175017818631658678 },
hash(HashBytes(&[0])) == if B32 { 2948228584 } else { 11037888512829180254 },
hash(HashBytes(&[0, 0, 0, 0, 0, 0])) == if B32 { 3223252423 } else { 6891281800865632452 },
hash(HashBytes(&[1])) == if B32 { 2943445104 } else { 4127763515449136980 },
hash(HashBytes(&[2])) == if B32 { 1055423297 } else { 11322700005987241762 },
hash(HashBytes(b"uwu")) == if B32 { 2699662140 } else { 2129615206728903013 },
hash(HashBytes(b"These are some bytes for testing rustc_hash.")) == if B32 { 2303640537 } else { 5513083560975408889 },
hash(HashBytes(&[])) == if B32 { 2673204745 } else { 17606491139363777937 },
hash(HashBytes(&[0])) == if B32 { 2948228584 } else { 5448590020104574886 },
hash(HashBytes(&[0, 0, 0, 0, 0, 0])) == if B32 { 3223252423 } else { 16766921560080789783 },
hash(HashBytes(&[1])) == if B32 { 2943445104 } else { 5922447956811044110 },
hash(HashBytes(&[2])) == if B32 { 1055423297 } else { 5229781508510959783 },
hash(HashBytes(b"uwu")) == if B32 { 2699662140 } else { 7168164714682931527 },
hash(HashBytes(b"These are some bytes for testing rustc_hash.")) == if B32 { 2303640537 } else { 2349210501944688211 },
}
}

Expand Down