Improve: Align inner hash-states

Author: ashvardanian

include/stringzilla/hash.h

@@ -698,7 +698,7 @@ SZ_PUBLIC sz_u64_t sz_hash_serial(sz_cptr_t start, sz_size_t length, sz_u64_t se
     else {
         // Use a larger state to handle the main loop and add different offsets
         // to different lanes of the register
-        sz_hash_state_t state;
+        _SZ_ALIGN64 sz_hash_state_t state;
         sz_hash_state_init_serial(&state, seed);
 
         for (; state.ins_length + 64 <= length; state.ins_length += 64) {
@@ -1039,7 +1039,7 @@ SZ_PUBLIC sz_u64_t sz_hash_haswell(sz_cptr_t start, sz_size_t length, sz_u64_t s
     else {
         // Use a larger state to handle the main loop and add different offsets
         // to different lanes of the register
-        sz_hash_state_t state;
+        _SZ_ALIGN64 sz_hash_state_t state;
         sz_hash_state_init_haswell(&state, seed);
         for (; state.ins_length + 64 <= length; state.ins_length += 64) {
             state.ins.xmms[0] = _mm_lddqu_si128((__m128i const *)(start + state.ins_length + 0));
@@ -1416,7 +1416,7 @@ SZ_PUBLIC sz_u64_t sz_hash_skylake(sz_cptr_t start, sz_size_t length, sz_u64_t s
     else {
         // Use a larger state to handle the main loop and add different offsets
         // to different lanes of the register
-        sz_hash_state_t state;
+        _SZ_ALIGN64 sz_hash_state_t state;
         sz_hash_state_init_skylake(&state, seed);
 
         for (; state.ins_length + 64 <= length; state.ins_length += 64) {
@@ -1676,7 +1676,7 @@ SZ_PUBLIC sz_u64_t sz_hash_ice(sz_cptr_t start, sz_size_t length, sz_u64_t seed)
     else {
         // Use a larger state to handle the main loop and add different offsets
         // to different lanes of the register
-        sz_hash_state_t state;
+        _SZ_ALIGN64 sz_hash_state_t state;
         sz_hash_state_init_skylake(&state, seed);
 
         for (; state.ins_length + 64 <= length; state.ins_length += 64) {
@@ -2107,7 +2107,7 @@ SZ_PUBLIC sz_u64_t sz_hash_neon(sz_cptr_t start, sz_size_t length, sz_u64_t seed
     else {
         // Use a larger state to handle the main loop and add different offsets
         // to different lanes of the register
-        sz_hash_state_t state;
+        _SZ_ALIGN64 sz_hash_state_t state;
         sz_hash_state_init_neon(&state, seed);
         for (; state.ins_length + 64 <= length; state.ins_length += 64) {
             state.ins.u8x16s[0] = vld1q_u8((sz_u8_t const *)(start + state.ins_length + 0));

rust/lib.rs

@@ -33,6 +33,7 @@ pub mod sz {
 
     #[repr(C)]
     #[derive(Debug, Clone, Copy)]
+    #[repr(align(64))] // For optimal performance we align to 64 bytes.
     pub struct HashState {
         aes: [u64; 8],
         sum: [u64; 8],
@@ -2027,7 +2028,9 @@ mod tests {
 
     #[test]
     fn hash() {
-        assert_ne!(sz::hash("Hello"), sz::hash("World"));
+        let hash_hello = sz::hash("Hello");
+        let hash_world = sz::hash("World");
+        assert_ne!(hash_hello, hash_world);
 
         // Hashing should work the same for any seed
         for seed in [0u64, 42, 123456789].iter() {