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Diffstat (limited to 'compiler/rustc_data_structures/src/stable_hasher/tests.rs')
-rw-r--r-- | compiler/rustc_data_structures/src/stable_hasher/tests.rs | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/compiler/rustc_data_structures/src/stable_hasher/tests.rs b/compiler/rustc_data_structures/src/stable_hasher/tests.rs new file mode 100644 index 000000000..b0d66c32a --- /dev/null +++ b/compiler/rustc_data_structures/src/stable_hasher/tests.rs @@ -0,0 +1,163 @@ +use super::*; + +// The tests below compare the computed hashes to particular expected values +// in order to test that we produce the same results on different platforms, +// regardless of endianness and `usize` and `isize` size differences (this +// of course assumes we run these tests on platforms that differ in those +// ways). The expected values depend on the hashing algorithm used, so they +// need to be updated whenever StableHasher changes its hashing algorithm. + +#[test] +fn test_hash_integers() { + // Test that integers are handled consistently across platforms. + let test_u8 = 0xAB_u8; + let test_u16 = 0xFFEE_u16; + let test_u32 = 0x445577AA_u32; + let test_u64 = 0x01234567_13243546_u64; + let test_u128 = 0x22114433_66557788_99AACCBB_EEDDFF77_u128; + let test_usize = 0xD0C0B0A0_usize; + + let test_i8 = -100_i8; + let test_i16 = -200_i16; + let test_i32 = -300_i32; + let test_i64 = -400_i64; + let test_i128 = -500_i128; + let test_isize = -600_isize; + + let mut h = StableHasher::new(); + test_u8.hash(&mut h); + test_u16.hash(&mut h); + test_u32.hash(&mut h); + test_u64.hash(&mut h); + test_u128.hash(&mut h); + test_usize.hash(&mut h); + test_i8.hash(&mut h); + test_i16.hash(&mut h); + test_i32.hash(&mut h); + test_i64.hash(&mut h); + test_i128.hash(&mut h); + test_isize.hash(&mut h); + + // This depends on the hashing algorithm. See note at top of file. + let expected = (1784307454142909076, 11471672289340283879); + + assert_eq!(h.finalize(), expected); +} + +#[test] +fn test_hash_usize() { + // Test that usize specifically is handled consistently across platforms. + let test_usize = 0xABCDEF01_usize; + + let mut h = StableHasher::new(); + test_usize.hash(&mut h); + + // This depends on the hashing algorithm. See note at top of file. + let expected = (5798740672699530587, 11186240177685111648); + + assert_eq!(h.finalize(), expected); +} + +#[test] +fn test_hash_isize() { + // Test that isize specifically is handled consistently across platforms. + let test_isize = -7_isize; + + let mut h = StableHasher::new(); + test_isize.hash(&mut h); + + // This depends on the hashing algorithm. See note at top of file. + let expected = (2789913510339652884, 674280939192711005); + + assert_eq!(h.finalize(), expected); +} + +fn hash<T: HashStable<()>>(t: &T) -> u128 { + let mut h = StableHasher::new(); + let ctx = &mut (); + t.hash_stable(ctx, &mut h); + h.finish() +} + +// Check that bit set hash includes the domain size. +#[test] +fn test_hash_bit_set() { + use rustc_index::bit_set::BitSet; + let a: BitSet<usize> = BitSet::new_empty(1); + let b: BitSet<usize> = BitSet::new_empty(2); + assert_ne!(a, b); + assert_ne!(hash(&a), hash(&b)); +} + +// Check that bit matrix hash includes the matrix dimensions. +#[test] +fn test_hash_bit_matrix() { + use rustc_index::bit_set::BitMatrix; + let a: BitMatrix<usize, usize> = BitMatrix::new(1, 1); + let b: BitMatrix<usize, usize> = BitMatrix::new(1, 2); + assert_ne!(a, b); + assert_ne!(hash(&a), hash(&b)); +} + +// Check that exchanging the value of two adjacent fields changes the hash. +#[test] +fn test_attribute_permutation() { + macro_rules! test_type { + ($ty: ty) => {{ + struct Foo { + a: $ty, + b: $ty, + } + + impl<CTX> HashStable<CTX> for Foo { + fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) { + self.a.hash_stable(hcx, hasher); + self.b.hash_stable(hcx, hasher); + } + } + + #[allow(overflowing_literals)] + let mut item = Foo { a: 0xFF, b: 0xFF_FF }; + let hash_a = hash(&item); + std::mem::swap(&mut item.a, &mut item.b); + let hash_b = hash(&item); + assert_ne!( + hash_a, + hash_b, + "The hash stayed the same after values were swapped for type `{}`!", + stringify!($ty) + ); + }}; + } + + test_type!(u16); + test_type!(u32); + test_type!(u64); + test_type!(u128); + + test_type!(i16); + test_type!(i32); + test_type!(i64); + test_type!(i128); +} + +// Check that the `isize` hashing optimization does not produce the same hash when permuting two +// values. +#[test] +fn test_isize_compression() { + fn check_hash(a: u64, b: u64) { + let hash_a = hash(&(a as isize, b as isize)); + let hash_b = hash(&(b as isize, a as isize)); + assert_ne!( + hash_a, hash_b, + "The hash stayed the same when permuting values `{a}` and `{b}!", + ); + } + + check_hash(0xAA, 0xAAAA); + check_hash(0xFF, 0xFFFF); + check_hash(0xAAAA, 0xAAAAAA); + check_hash(0xAAAAAA, 0xAAAAAAAA); + check_hash(0xFF, 0xFFFFFFFFFFFFFFFF); + check_hash(u64::MAX /* -1 */, 1); +} |