fix: avoid huge unrolling in hash_args (#5703)

After noir-lang/noir#4736 was fixed, now this is possible :) --------- Co-authored-by: Alvaro Rodriguez <sirasistant@MacBook-Pro-de-Alvaro.local>
AztecProtocol · Apr 13, 2024 · d199966 · d199966
1 parent a0e00e2
commit d199966
Showing 1 changed file with 16 additions and 13 deletions.
diff --git a/aztec/src/hash.nr b/aztec/src/hash.nr
@@ -89,21 +89,24 @@ pub fn hash_args(args: [Field]) -> Field {
     if args.len() == 0 {
         0
     } else {
+        assert(args.len() < ARGS_HASH_CHUNK_COUNT * ARGS_HASH_CHUNK_LENGTH);
         let mut chunks_hashes = [0; ARGS_HASH_CHUNK_COUNT];
-        for i in 0..ARGS_HASH_CHUNK_COUNT {
-            let mut chunk_hash = 0;
-            let start_chunk_index = i * ARGS_HASH_CHUNK_LENGTH;
-            if start_chunk_index < args.len() {
-                let mut chunk_args = [0; ARGS_HASH_CHUNK_LENGTH];
-                for j in 0..ARGS_HASH_CHUNK_LENGTH {
-                    let item_index = i * ARGS_HASH_CHUNK_LENGTH + j;
-                    if item_index < args.len() {
-                        chunk_args[j] = args[item_index];
-                    }
-                }
-                chunk_hash = pedersen_hash(chunk_args, GENERATOR_INDEX__FUNCTION_ARGS);
+        let mut current_chunk_values = [0; ARGS_HASH_CHUNK_LENGTH];
+
+        let mut current_chunk_index = 0;
+        let mut index_inside_current_chunk = 0;
+        for i in 0..args.len() {
+            current_chunk_values[index_inside_current_chunk] = args[i];
+            index_inside_current_chunk+=1;
+            if index_inside_current_chunk == ARGS_HASH_CHUNK_LENGTH {
+                chunks_hashes[current_chunk_index] = pedersen_hash(current_chunk_values, GENERATOR_INDEX__FUNCTION_ARGS);
+                current_chunk_values = [0; ARGS_HASH_CHUNK_LENGTH];
+                current_chunk_index+=1;
+                index_inside_current_chunk = 0;
             }
-            chunks_hashes[i] = chunk_hash;
+        }
+        if index_inside_current_chunk > 0 {
+            chunks_hashes[current_chunk_index] = pedersen_hash(current_chunk_values, GENERATOR_INDEX__FUNCTION_ARGS);
         }
         pedersen_hash(chunks_hashes, GENERATOR_INDEX__FUNCTION_ARGS)
     }