remove empty account handling code

Author: gurukamath

src/ethereum/cancun/fork.py

@@ -35,7 +35,6 @@
     TransientStorage,
     account_exists_and_is_empty,
     destroy_account,
-    destroy_touched_empty_accounts,
     get_account,
     increment_nonce,
     modify_state,
@@ -538,15 +537,6 @@ def process_system_transaction(
 
     system_tx_output = process_message_call(system_tx_message)
 
-    # TODO: Empty accounts in post-merge forks are impossible
-    # see Ethereum Improvement Proposal 7523.
-    # This line is only included to support invalid tests in the test suite
-    # and will have to be removed in the future.
-    # See https://github.com/ethereum/execution-specs/issues/955
-    destroy_touched_empty_accounts(
-        block_env.state, system_tx_output.touched_accounts
-    )
-
     return system_tx_output
 
 
@@ -722,8 +712,6 @@ def process_transaction(
     for address in tx_output.accounts_to_delete:
         destroy_account(block_env.state, address)
 
-    destroy_touched_empty_accounts(block_env.state, tx_output.touched_accounts)
-
     block_output.block_gas_used += tx_gas_used
     block_output.blob_gas_used += tx_blob_gas_used
 

src/ethereum/cancun/state.py

@@ -510,6 +510,8 @@ def modify_state(
     Modify an `Account` in the `State`.
     """
     set_account(state, address, modify(get_account(state, address), f))
+    if account_exists_and_is_empty(state, address):
+        destroy_account(state, address)
 
 
 def move_ether(
@@ -556,22 +558,6 @@ def set_balance(account: Account) -> None:
     modify_state(state, address, set_balance)
 
 
-def touch_account(state: State, address: Address) -> None:
-    """
-    Initializes an account to state.
-
-    Parameters
-    ----------
-    state:
-        The current state.
-
-    address:
-        The address of the account that need to initialised.
-    """
-    if not account_exists(state, address):
-        set_account(state, address, EMPTY_ACCOUNT)
-
-
 def increment_nonce(state: State, address: Address) -> None:
     """
     Increments the nonce of an account.
@@ -702,20 +688,3 @@ def set_transient_storage(
     trie_set(trie, key, value)
     if trie._data == {}:
         del transient_storage._tries[address]
-
-
-def destroy_touched_empty_accounts(
-    state: State, touched_accounts: Set[Address]
-) -> None:
-    """
-    Destroy all touched accounts that are empty.
-    Parameters
-    ----------
-    state: `State`
-        The current state.
-    touched_accounts: `Set[Address]`
-        All the accounts that have been touched in the current transaction.
-    """
-    for address in touched_accounts:
-        if account_exists_and_is_empty(state, address):
-            destroy_account(state, address)

src/ethereum/cancun/vm/__init__.py

@@ -24,10 +24,9 @@
 
 from ..blocks import Log, Receipt, Withdrawal
 from ..fork_types import Address, VersionedHash
-from ..state import State, TransientStorage, account_exists_and_is_empty
+from ..state import State, TransientStorage
 from ..transactions import LegacyTransaction
 from ..trie import Trie
-from .precompiled_contracts import RIPEMD160_ADDRESS
 
 __all__ = ("Environment", "Evm", "Message")
 
@@ -145,7 +144,6 @@ class Evm:
     message: Message
     output: Bytes
     accounts_to_delete: Set[Address]
-    touched_accounts: Set[Address]
     return_data: Bytes
     error: Optional[EthereumException]
     accessed_addresses: Set[Address]
@@ -167,11 +165,6 @@ def incorporate_child_on_success(evm: Evm, child_evm: Evm) -> None:
     evm.logs += child_evm.logs
     evm.refund_counter += child_evm.refund_counter
     evm.accounts_to_delete.update(child_evm.accounts_to_delete)
-    evm.touched_accounts.update(child_evm.touched_accounts)
-    if account_exists_and_is_empty(
-        evm.message.block_env.state, child_evm.message.current_target
-    ):
-        evm.touched_accounts.add(child_evm.message.current_target)
     evm.accessed_addresses.update(child_evm.accessed_addresses)
     evm.accessed_storage_keys.update(child_evm.accessed_storage_keys)
 
@@ -187,18 +180,4 @@ def incorporate_child_on_error(evm: Evm, child_evm: Evm) -> None:
     child_evm :
         The child evm to incorporate.
     """
-    # In block 2675119, the empty account at 0x3 (the RIPEMD160 precompile) was
-    # cleared despite running out of gas. This is an obscure edge case that can
-    # only happen to a precompile.
-    # According to the general rules governing clearing of empty accounts, the
-    # touch should have been reverted. Due to client bugs, this event went
-    # unnoticed and 0x3 has been exempted from the rule that touches are
-    # reverted in order to preserve this historical behaviour.
-    if RIPEMD160_ADDRESS in child_evm.touched_accounts:
-        evm.touched_accounts.add(RIPEMD160_ADDRESS)
-    if child_evm.message.current_target == RIPEMD160_ADDRESS:
-        if account_exists_and_is_empty(
-            evm.message.block_env.state, child_evm.message.current_target
-        ):
-            evm.touched_accounts.add(RIPEMD160_ADDRESS)
     evm.gas_left += child_evm.gas_left

src/ethereum/cancun/vm/instructions/system.py

@@ -19,7 +19,6 @@
 
 from ...fork_types import Address
 from ...state import (
-    account_exists_and_is_empty,
     account_has_code_or_nonce,
     account_has_storage,
     get_account,
@@ -546,10 +545,6 @@ def selfdestruct(evm: Evm) -> None:
         set_account_balance(evm.message.block_env.state, originator, U256(0))
         evm.accounts_to_delete.add(originator)
 
-    # mark beneficiary as touched
-    if account_exists_and_is_empty(evm.message.block_env.state, beneficiary):
-        evm.touched_accounts.add(beneficiary)
-
     # HALT the execution
     evm.running = False
 

src/ethereum/cancun/vm/interpreter.py

@@ -33,7 +33,6 @@
 from ..blocks import Log
 from ..fork_types import Address
 from ..state import (
-    account_exists_and_is_empty,
     account_has_code_or_nonce,
     account_has_storage,
     begin_transaction,
@@ -44,7 +43,6 @@
     move_ether,
     rollback_transaction,
     set_code,
-    touch_account,
 )
 from ..vm import Message
 from ..vm.gas import GAS_CODE_DEPOSIT, charge_gas
@@ -77,15 +75,13 @@ class MessageCallOutput:
           2. `refund_counter`: gas to refund after execution.
           3. `logs`: list of `Log` generated during execution.
           4. `accounts_to_delete`: Contracts which have self-destructed.
-          5. `touched_accounts`: Accounts that have been touched.
-          6. `error`: The error from the execution if any.
+          5. `error`: The error from the execution if any.
     """
 
     gas_left: Uint
     refund_counter: U256
     logs: Tuple[Log, ...]
     accounts_to_delete: Set[Address]
-    touched_accounts: Set[Address]
     error: Optional[EthereumException]
 
 
@@ -112,25 +108,19 @@ def process_message_call(message: Message) -> MessageCallOutput:
         ) or account_has_storage(block_env.state, message.current_target)
         if is_collision:
             return MessageCallOutput(
-                Uint(0), U256(0), tuple(), set(), set(), AddressCollision()
+                Uint(0), U256(0), tuple(), set(), AddressCollision()
             )
         else:
             evm = process_create_message(message)
     else:
         evm = process_message(message)
-        if account_exists_and_is_empty(
-            block_env.state, Address(message.target)
-        ):
-            evm.touched_accounts.add(Address(message.target))
 
     if evm.error:
         logs: Tuple[Log, ...] = ()
         accounts_to_delete = set()
-        touched_accounts = set()
     else:
         logs = evm.logs
         accounts_to_delete = evm.accounts_to_delete
-        touched_accounts = evm.touched_accounts
         refund_counter += U256(evm.refund_counter)
 
     tx_end = TransactionEnd(
@@ -143,7 +133,6 @@ def process_message_call(message: Message) -> MessageCallOutput:
         refund_counter=refund_counter,
         logs=logs,
         accounts_to_delete=accounts_to_delete,
-        touched_accounts=touched_accounts,
         error=evm.error,
     )
 
@@ -232,8 +221,6 @@ def process_message(message: Message) -> Evm:
     # take snapshot of state before processing the message
     begin_transaction(state, transient_storage)
 
-    touch_account(state, message.current_target)
-
     if message.should_transfer_value and message.value != 0:
         move_ether(
             state, message.caller, message.current_target, message.value
@@ -281,7 +268,6 @@ def execute_code(message: Message) -> Evm:
         message=message,
         output=b"",
         accounts_to_delete=set(),
-        touched_accounts=set(),
         return_data=b"",
         error=None,
         accessed_addresses=message.accessed_addresses,

src/ethereum/exceptions.py

@@ -16,6 +16,12 @@ class InvalidBlock(EthereumException):
     """
 
 
+class StateWithEmptyAccount(EthereumException):
+    """
+    Thrown when the state has empty account.
+    """
+
+
 class InvalidTransaction(EthereumException):
     """
     Thrown when a transaction being processed is found to be invalid.

src/ethereum/paris/fork.py

@@ -34,7 +34,6 @@
     State,
     account_exists_and_is_empty,
     destroy_account,
-    destroy_touched_empty_accounts,
     get_account,
     increment_nonce,
     set_account_balance,
@@ -564,8 +563,6 @@ def process_transaction(
     for address in tx_output.accounts_to_delete:
         destroy_account(block_env.state, address)
 
-    destroy_touched_empty_accounts(block_env.state, tx_output.touched_accounts)
-
     block_output.block_gas_used += tx_gas_used
 
     receipt = make_receipt(

src/ethereum/paris/state.py

@@ -17,7 +17,7 @@
 `EMPTY_ACCOUNT`.
 """
 from dataclasses import dataclass, field
-from typing import Callable, Dict, Iterable, List, Optional, Set, Tuple
+from typing import Callable, Dict, List, Optional, Set, Tuple
 
 from ethereum_types.bytes import Bytes, Bytes32
 from ethereum_types.frozen import modify
@@ -477,6 +477,8 @@ def modify_state(
     Modify an `Account` in the `State`.
     """
     set_account(state, address, modify(get_account(state, address), f))
+    if account_exists_and_is_empty(state, address):
+        destroy_account(state, address)
 
 
 def move_ether(
@@ -523,22 +525,6 @@ def set_balance(account: Account) -> None:
     modify_state(state, address, set_balance)
 
 
-def touch_account(state: State, address: Address) -> None:
-    """
-    Initializes an account to state.
-
-    Parameters
-    ----------
-    state:
-        The current state.
-
-    address:
-        The address of the account that need to initialised.
-    """
-    if not account_exists(state, address):
-        set_account(state, address, EMPTY_ACCOUNT)
-
-
 def increment_nonce(state: State, address: Address) -> None:
     """
     Increments the nonce of an account.
@@ -611,20 +597,3 @@ def get_storage_original(state: State, address: Address, key: Bytes32) -> U256:
     assert isinstance(original_value, U256)
 
     return original_value
-
-
-def destroy_touched_empty_accounts(
-    state: State, touched_accounts: Iterable[Address]
-) -> None:
-    """
-    Destroy all touched accounts that are empty.
-    Parameters
-    ----------
-    state: `State`
-        The current state.
-    touched_accounts: `Iterable[Address]`
-        All the accounts that have been touched in the current transaction.
-    """
-    for address in touched_accounts:
-        if account_exists_and_is_empty(state, address):
-            destroy_account(state, address)

src/ethereum/paris/vm/__init__.py

@@ -24,10 +24,9 @@
 
 from ..blocks import Log, Receipt
 from ..fork_types import Address
-from ..state import State, account_exists_and_is_empty
+from ..state import State
 from ..transactions import LegacyTransaction
 from ..trie import Trie
-from .precompiled_contracts import RIPEMD160_ADDRESS
 
 __all__ = ("Environment", "Evm", "Message")
 
@@ -133,7 +132,6 @@ class Evm:
     message: Message
     output: Bytes
     accounts_to_delete: Set[Address]
-    touched_accounts: Set[Address]
     return_data: Bytes
     error: Optional[EthereumException]
     accessed_addresses: Set[Address]
@@ -155,11 +153,6 @@ def incorporate_child_on_success(evm: Evm, child_evm: Evm) -> None:
     evm.logs += child_evm.logs
     evm.refund_counter += child_evm.refund_counter
     evm.accounts_to_delete.update(child_evm.accounts_to_delete)
-    evm.touched_accounts.update(child_evm.touched_accounts)
-    if account_exists_and_is_empty(
-        evm.message.block_env.state, child_evm.message.current_target
-    ):
-        evm.touched_accounts.add(child_evm.message.current_target)
     evm.accessed_addresses.update(child_evm.accessed_addresses)
     evm.accessed_storage_keys.update(child_evm.accessed_storage_keys)
 
@@ -175,18 +168,4 @@ def incorporate_child_on_error(evm: Evm, child_evm: Evm) -> None:
     child_evm :
         The child evm to incorporate.
     """
-    # In block 2675119, the empty account at 0x3 (the RIPEMD160 precompile) was
-    # cleared despite running out of gas. This is an obscure edge case that can
-    # only happen to a precompile.
-    # According to the general rules governing clearing of empty accounts, the
-    # touch should have been reverted. Due to client bugs, this event went
-    # unnoticed and 0x3 has been exempted from the rule that touches are
-    # reverted in order to preserve this historical behaviour.
-    if RIPEMD160_ADDRESS in child_evm.touched_accounts:
-        evm.touched_accounts.add(RIPEMD160_ADDRESS)
-    if child_evm.message.current_target == RIPEMD160_ADDRESS:
-        if account_exists_and_is_empty(
-            evm.message.block_env.state, child_evm.message.current_target
-        ):
-            evm.touched_accounts.add(RIPEMD160_ADDRESS)
     evm.gas_left += child_evm.gas_left