EIP-4788: Make it clear what is an EVM system call

nimbus/core/executor/process_transaction.nim

@@ -140,32 +140,26 @@ proc processBeaconBlockRoot*(vmState: BaseVMState, beaconRoot: Hash256):
   let
     statedb = vmState.stateDB
     call = CallParams(
-      vmState:  vmState,
-      sender:   SystemAddress,
-      gasLimit: 30_000_000.GasInt,
-      gasPrice: 0.GasInt,
-      to:       BeaconRootsStorageAddress,
-      input:    @(beaconRoot.data),
+      vmState  : vmState,
+      sender   : SystemAddress,
+      gasLimit : 30_000_000.GasInt,
+      gasPrice : 0.GasInt,
+      to       : BeaconRootsStorageAddress,
+      input    : @(beaconRoot.data),
+
+      # It's a systemCall, no need for other knicks knacks
+      sysCall     : true,
+      noAccessList: true,
+      noIntrinsic : true,
+      noGasCharge : true,
+      noRefund    : true,
     )
 
   # runComputation a.k.a syscall/evm.call
   if call.runComputation().isError:
     return err("processBeaconBlockRoot: syscall error")
 
-  # We can choose to set SystemAddress nonce to 0
-  # like erigon or geth(their EVM have explicit nonce set)
-  # or we delete the account manually instead of let it deleted
-  # by AccountsCache.persist.
-  statedb.deleteAccount(SystemAddress)
-
-  when false:
-    # nimbus EVM automatically increase sender nonce by one
-    # for each call/create.
-    statedb.setNonce(SystemAddress, 0)
-    # statedb.persist probably not needed as each processTransaction
-    # will call it.
-    statedb.persist(clearEmptyAccount = true, clearCache = false)
-
+  statedb.persist(clearEmptyAccount = true, clearCache = false)
   ok()
 
 proc asyncProcessTransaction*(

nimbus/db/accounts_cache.nim

@@ -448,7 +448,7 @@ proc setBalance*(ac: AccountsCache, address: EthAddress, balance: UInt256) =
 proc addBalance*(ac: AccountsCache, address: EthAddress, delta: UInt256) {.inline.} =
   # EIP161: We must check emptiness for the objects such that the account
   # clearing (0,0,0 objects) can take effect.
-  if delta == 0.u256:
+  if delta.isZero:
     let acc = ac.getAccount(address)
     if acc.isEmpty:
       ac.makeDirty(address).flags.incl Touched
@@ -456,6 +456,12 @@ proc addBalance*(ac: AccountsCache, address: EthAddress, delta: UInt256) {.inlin
   ac.setBalance(address, ac.getBalance(address) + delta)
 
 proc subBalance*(ac: AccountsCache, address: EthAddress, delta: UInt256) {.inline.} =
+  if delta.isZero:
+    # This zero delta early exit is important as shown in EIP-4788.
+    # If the account is created, it will change the state.
+    # But early exit will prevent the account creation.
+    # In this case, the SystemAddress
+    return
   ac.setBalance(address, ac.getBalance(address) - delta)
 
 proc setNonce*(ac: AccountsCache, address: EthAddress, nonce: AccountNonce) =

nimbus/evm/computation.nim

@@ -212,7 +212,7 @@ template getTransientStorage*(c: Computation, slot: UInt256): UInt256 =
     c.vmState.readOnlyStateDB.
       getTransientStorage(c.msg.contractAddress, slot)
 
-proc newComputation*(vmState: BaseVMState, message: Message,
+proc newComputation*(vmState: BaseVMState, sysCall: bool, message: Message,
                      salt: ContractSalt = ZERO_CONTRACTSALT): Computation =
   new result
   result.vmState = vmState
@@ -221,6 +221,7 @@ proc newComputation*(vmState: BaseVMState, message: Message,
   result.stack = newStack()
   result.returnStack = @[]
   result.gasMeter.init(message.gas)
+  result.sysCall = sysCall
 
   if result.msg.isCreate():
     result.msg.contractAddress = result.generateContractAddress(salt)
@@ -230,7 +231,8 @@ proc newComputation*(vmState: BaseVMState, message: Message,
     result.code = newCodeStream(
       vmState.readOnlyStateDB.getCode(message.codeAddress))
 
-proc newComputation*(vmState: BaseVMState, message: Message, code: seq[byte]): Computation =
+proc newComputation*(vmState: BaseVMState, sysCall: bool,
+                     message: Message, code: seq[byte]): Computation =
   new result
   result.vmState = vmState
   result.msg = message
@@ -239,6 +241,7 @@ proc newComputation*(vmState: BaseVMState, message: Message, code: seq[byte]): C
   result.returnStack = @[]
   result.gasMeter.init(message.gas)
   result.code = newCodeStream(code)
+  result.sysCall = sysCall
 
 template gasCosts*(c: Computation): untyped =
   c.vmState.gasCosts

nimbus/evm/interpreter/op_handlers/oph_call.nim

@@ -172,7 +172,7 @@ else:
     # need to provide explicit <c> and <child> for capturing in chainTo proc()
     # <memPos> and <memLen> are provided by value and need not be captured
     var
-      child = newComputation(c.vmState, childMsg)
+      child = newComputation(c.vmState, false, childMsg)
 
     c.chainTo(child):
       if not child.shouldBurnGas:

nimbus/evm/interpreter/op_handlers/oph_create.nim

@@ -63,7 +63,7 @@ else:
 
     # need to provide explicit <c> and <child> for capturing in chainTo proc()
     var
-      child = newComputation(c.vmState, childMsg, salt)
+      child = newComputation(c.vmState, false, childMsg, salt)
 
     c.chainTo(child):
       if not child.shouldBurnGas:

nimbus/evm/state_transactions.nim

@@ -63,6 +63,9 @@ proc execComputation*(c: Computation)
   c.execCallOrCreate()
   c.postExecComputation()
 
+template execSysCall*(c: Computation) =
+  c.execCallOrCreate()
+
 # FIXME-duplicatedForAsync
 proc asyncExecComputation*(c: Computation): Future[void] {.async.} =
   c.preExecComputation()

nimbus/evm/types.nim

@@ -87,6 +87,7 @@ type
       parent*, child*:      Computation
     pendingAsyncOperation*: Future[void]
     continuation*:          proc() {.gcsafe, raises: [CatchableError].}
+    sysCall*:               bool
 
   Error* = ref object
     statusCode*: evmc_status_code

nimbus/transaction/call_common.nim

@@ -42,6 +42,7 @@ type
     noAccessList*: bool                 # Don't initialise EIP-2929 access list.
     noGasCharge*:  bool                 # Don't charge sender account for gas.
     noRefund*:     bool                 # Don't apply gas refund/burn rule.
+    sysCall*:      bool                 # System call or ordinary call
 
   # Standard call result.  (Some fields are beyond what EVMC can return,
   # and must only be used from tests because they will not always be set).
@@ -176,7 +177,7 @@ proc setupHost(call: CallParams): TransactionHost =
         host.msg.input_data = host.input[0].addr
 
     let cMsg = hostToComputationMessage(host.msg)
-    host.computation = newComputation(vmState, cMsg, code)
+    host.computation = newComputation(vmState, call.sysCall, cMsg, code)
 
     shallowCopy(host.code, code)
 
@@ -189,7 +190,7 @@ proc setupHost(call: CallParams): TransactionHost =
       host.msg.input_data = host.input[0].addr
 
     let cMsg = hostToComputationMessage(host.msg)
-    host.computation = newComputation(vmState, cMsg)
+    host.computation = newComputation(vmState, call.sysCall, cMsg)
 
   vmState.captureStart(host.computation, call.sender, call.to,
                        call.isCreate, call.input,
@@ -297,7 +298,10 @@ proc runComputation*(call: CallParams): CallResult
   when defined(evmc_enabled):
     doExecEvmc(host, call)
   else:
-    execComputation(host.computation)
+    if host.computation.sysCall:
+      execSysCall(host.computation)
+    else:
+      execComputation(host.computation)
 
   finishRunningComputation(host, call)
 

nimbus/transaction/evmc_vm_glue.nim

@@ -38,7 +38,10 @@ proc evmcExecute(vm: ptr evmc_vm, hostInterface: ptr evmc_host_interface,
   #  host.computation = c
 
   c.host.init(cast[ptr nimbus_host_interface](hostInterface), hostContext)
-  execComputation(c)
+  if c.sysCall:
+    execSysCall(c)
+  else:
+    execComputation(c)
 
   # When output size is zero, output data pointer may be null.
   var output_data: ptr byte

nimbus/transaction/host_call_nested.nim

@@ -30,7 +30,7 @@ proc beforeExecCreateEvmcNested(host: TransactionHost,
     value: m.value.fromEvmc,
     data: @(makeOpenArray(m.inputData, m.inputSize.int))
   )
-  return newComputation(host.vmState, childMsg,
+  return newComputation(host.vmState, false, childMsg,
                         cast[ContractSalt](m.create2_salt))
 
 proc afterExecCreateEvmcNested(host: TransactionHost, child: Computation,
@@ -67,7 +67,7 @@ proc beforeExecCallEvmcNested(host: TransactionHost,
     data: @(makeOpenArray(m.inputData, m.inputSize.int)),
     flags: m.flags,
   )
-  return newComputation(host.vmState, childMsg)
+  return newComputation(host.vmState, false, childMsg)
 
 proc afterExecCallEvmcNested(host: TransactionHost, child: Computation,
                              res: var EvmcResult) {.inline.} =

nimbus/vm_state_transactions.nim

@@ -13,6 +13,7 @@ import
 
 export
   vmx.asyncExecComputation,
-  vmx.execComputation
+  vmx.execComputation,
+  vmx.execSysCall
 
 # End