feat(blockifier): implement get_clash_at syscall for native (#2160)

crates/blockifier/src/execution/native/entry_point_execution.rs

@@ -98,11 +98,8 @@ fn create_callinfo(
         inner_calls: syscall_handler.inner_calls,
         storage_read_values: syscall_handler.read_values,
         accessed_storage_keys: syscall_handler.accessed_keys,
-        // TODO(Aviv): The syscall is not supported here yet.
-        // Currently, `accessed_contract_addresses` and `read_class_hash_values` are initialized
-        // as empty. Support for handling accessed storage keys via syscalls should be implemented.
-        accessed_contract_addresses: Default::default(),
-        read_class_hash_values: Default::default(),
+        accessed_contract_addresses: syscall_handler.accessed_contract_addresses,
+        read_class_hash_values: syscall_handler.read_class_hash_values,
         tracked_resource: TrackedResource::SierraGas,
     })
 }

crates/blockifier/src/execution/native/syscall_handler.rs

@@ -76,6 +76,9 @@ pub struct NativeSyscallHandler<'state> {
     // Additional information gathered during execution.
     pub read_values: Vec<Felt>,
     pub accessed_keys: HashSet<StorageKey, RandomState>,
+    pub read_class_hash_values: Vec<ClassHash>,
+    // Accessed addresses by the `get_class_hash_at` syscall.
+    pub accessed_contract_addresses: HashSet<ContractAddress>,
 
     // It is set if an unrecoverable error happens during syscall execution
     pub unrecoverable_error: Option<SyscallExecutionError>,
@@ -98,6 +101,8 @@ impl<'state> NativeSyscallHandler<'state> {
             inner_calls: Vec::new(),
             read_values: Vec::new(),
             accessed_keys: HashSet::new(),
+            read_class_hash_values: Vec::new(),
+            accessed_contract_addresses: HashSet::new(),
             unrecoverable_error: None,
         }
     }
@@ -297,10 +302,24 @@ impl<'state> StarknetSyscallHandler for &mut NativeSyscallHandler<'state> {
 
     fn get_class_hash_at(
         &mut self,
-        _contract_address: Felt,
-        _remaining_gas: &mut u128,
+        contract_address: Felt,
+        remaining_gas: &mut u128,
     ) -> SyscallResult<Felt> {
-        todo!()
+        self.pre_execute_syscall(
+            remaining_gas,
+            self.context.gas_costs().get_class_hash_at_gas_cost,
+        )?;
+        let request = ContractAddress::try_from(contract_address)
+            .map_err(|err| self.handle_error(remaining_gas, err.into()))?;
+        self.accessed_contract_addresses.insert(request);
+
+        let class_hash = self
+            .state
+            .get_class_hash_at(request)
+            .map_err(|err| self.handle_error(remaining_gas, err.into()))?;
+        self.read_class_hash_values.push(class_hash);
+
+        Ok(class_hash.0)
     }
 
     fn get_execution_info_v2(

crates/blockifier/src/execution/syscalls/syscall_tests/get_class_hash_at.rs

@@ -18,6 +18,10 @@ use crate::test_utils::{trivial_external_entry_point_new, CairoVersion, BALANCE}
 /// 4. Execution fails if `address` has a different `class_hash`.
 /// 5. Execution succeeds and returns `class_hash` = 0 if `address` is absent.
 #[test_case(FeatureContract::TestContract(CairoVersion::Cairo1), REQUIRED_GAS_GET_CLASS_HASH_AT_TEST; "VM")]
+#[cfg_attr(
+    feature = "cairo_native",
+    test_case(FeatureContract::TestContract(CairoVersion::Native), 17830; "Native"))
+]
 fn test_get_class_hash_at(test_contract: FeatureContract, expected_gas: u64) {
     let chain_info = &ChainInfo::create_for_testing();
     let mut state = test_state(chain_info, BALANCE, &[(test_contract, 1)]);