Optimize SipHash by reordering compress instructions

model-checking · Jul 1, 2024 · 645e9f2 · 645e9f2
1 parent 2a65e9f
commit 645e9f2
Showing 1 changed file with 6 additions and 5 deletions.
diff --git a/core/src/hash/sip.rs b/core/src/hash/sip.rs
@@ -76,18 +76,19 @@ macro_rules! compress {
     ($state:expr) => {{ compress!($state.v0, $state.v1, $state.v2, $state.v3) }};
     ($v0:expr, $v1:expr, $v2:expr, $v3:expr) => {{
         $v0 = $v0.wrapping_add($v1);
+        $v2 = $v2.wrapping_add($v3);
         $v1 = $v1.rotate_left(13);
         $v1 ^= $v0;
-        $v0 = $v0.rotate_left(32);
-        $v2 = $v2.wrapping_add($v3);
         $v3 = $v3.rotate_left(16);
         $v3 ^= $v2;
-        $v0 = $v0.wrapping_add($v3);
-        $v3 = $v3.rotate_left(21);
-        $v3 ^= $v0;
+        $v0 = $v0.rotate_left(32);
+
         $v2 = $v2.wrapping_add($v1);
+        $v0 = $v0.wrapping_add($v3);
         $v1 = $v1.rotate_left(17);
         $v1 ^= $v2;
+        $v3 = $v3.rotate_left(21);
+        $v3 ^= $v0;
         $v2 = $v2.rotate_left(32);
     }};
 }