Dont zero init

Author: EbbDrop

src/day25.rs

@@ -17,9 +17,13 @@ const KEPT_BITS: i8 = 0b011;
 unsafe fn part1_inner(s: &[u8]) -> u64 {
     let mut sum = 0;
 
-    let mut keys = [MaybeUninit::<__m256i>::uninit(); 512];
+    static mut KEYS: [__m256i; 512] = unsafe { std::mem::transmute([0u8; 512 * 32]) };
+    static mut HOLES: [__m256i; 512] = unsafe { std::mem::transmute([0u8; 512 * 32]) };
+
+    let keys = &mut *(&raw mut KEYS);
+    let holes = &mut *(&raw mut HOLES);
+
     let mut keys_i = 0;
-    let mut holes = [MaybeUninit::<__m256i>::uninit(); 512];
     let mut holes_i = 0;
 
     let mut i = 0;
@@ -46,7 +50,7 @@ unsafe fn part1_inner(s: &[u8]) -> u64 {
 
         if is_key {
             for i in 0..holes_i {
-                let o = holes.get_unchecked(i).assume_init_read();
+                let o = *holes.get_unchecked(i);
                 let collisions = _mm256_cmpeq_epi8(d, o);
                 let collisions = _mm256_movemask_epi8(collisions);
                 sum += (collisions == 0) as u64;
@@ -62,11 +66,11 @@ unsafe fn part1_inner(s: &[u8]) -> u64 {
                     0, 0, 0, 0, 0, -1, -1, -1,
                 ),
             );
-            keys.get_unchecked_mut(keys_i).write(d);
+            *keys.get_unchecked_mut(keys_i) = d;
             keys_i += 1;
         } else {
             for i in 0..keys_i {
-                let o = keys.get_unchecked(i).assume_init_read();
+                let o = *keys.get_unchecked(i);
                 let collisions = _mm256_cmpeq_epi8(d, o);
                 let collisions = _mm256_movemask_epi8(collisions);
                 sum += (collisions == 0) as u64;
@@ -82,7 +86,7 @@ unsafe fn part1_inner(s: &[u8]) -> u64 {
                     0, 0, 0, 0, 0, -1, -1, -1,
                 ),
             );
-            holes.get_unchecked_mut(holes_i).write(d);
+            *holes.get_unchecked_mut(holes_i) = d;
             holes_i += 1;
         }