London basefee opcode 0x48 (#2015)

* London basefee opcode

* raise NotImplementedError for basefee in base state

* Add newsfragment

* basefee -> base_fee

* move stack_pop1_int -> stack_pop1_any

Co-authored-by: Jason Carver <ut96caarrs@snkmail.com>

* basefee messaging and docs

Co-authored-by: Jason Carver <ut96caarrs@snkmail.com>

Author: kclowes

eth/abc.py

@@ -2670,6 +2670,17 @@ def gas_limit(self) -> int:
         """
         ...
 
+    @property
+    @abstractmethod
+    def base_fee(self) -> int:
+        """
+        Return the current ``base_fee`` from the current :attr:`~execution_context`
+
+        Raises a ``NotImplementedError`` if called in an execution context
+        prior to the London hard fork.
+        """
+        ...
+
     @abstractmethod
     def get_gas_price(self, transaction: SignedTransactionAPI) -> int:
         """

eth/vm/forks/london/computation.py

@@ -2,10 +2,12 @@
     BerlinComputation,
 )
 
+from .opcodes import LONDON_OPCODES
+
 
 class LondonComputation(BerlinComputation):
     """
     A class for all execution computations in the ``London`` fork.
     Inherits from :class:`~eth.vm.forks.berlin.BerlinComputation`
     """
-    pass
+    opcodes = LONDON_OPCODES

eth/vm/forks/london/opcodes.py

@@ -0,0 +1,36 @@
+import copy
+from typing import Dict
+
+from eth_utils.toolz import merge
+
+from eth.vm.logic import (
+    block,
+)
+from eth.vm import (
+    mnemonics,
+    opcode_values,
+)
+from eth.vm.opcode import (
+    Opcode,
+    as_opcode,
+)
+from eth import constants
+
+from eth.vm.forks.berlin.opcodes import (
+    BERLIN_OPCODES,
+)
+
+
+UPDATED_OPCODES: Dict[int, Opcode] = {
+    opcode_values.BASEFEE: as_opcode(
+        gas_cost=constants.GAS_BASE,
+        logic_fn=block.basefee,
+        mnemonic=mnemonics.BASEFEE,
+    ),
+}
+
+
+LONDON_OPCODES = merge(
+    copy.deepcopy(BERLIN_OPCODES),
+    UPDATED_OPCODES,
+)

eth/vm/forks/london/state.py

@@ -135,3 +135,7 @@ def get_transaction_context(self: StateAPI,
             gas_price=effective_gas_price,
             origin=transaction.sender
         )
+
+    @property
+    def base_fee(self: StateAPI) -> int:
+        return self.execution_context.base_fee_per_gas

eth/vm/logic/block.py

@@ -27,3 +27,7 @@ def difficulty(computation: BaseComputation) -> None:
 
 def gaslimit(computation: BaseComputation) -> None:
     computation.stack_push_int(computation.state.gas_limit)
+
+
+def basefee(computation: BaseComputation) -> None:
+    computation.stack_push_int(computation.state.base_fee)

eth/vm/mnemonics.py

@@ -64,6 +64,7 @@
 NUMBER = 'NUMBER'
 DIFFICULTY = 'DIFFICULTY'
 GASLIMIT = 'GASLIMIT'
+BASEFEE = 'BASEFEE'
 #
 # Stack, Memory, Storage and Flow Operations
 #

eth/vm/opcode_values.py

@@ -63,6 +63,7 @@
 # These opcodes seem to belong in the environment block, but we are out of opcode space in 0x3*
 CHAINID = 0x46
 SELFBALANCE = 0x47
+BASEFEE = 0x48
 
 #
 # Block Information

eth/vm/state.py

@@ -88,6 +88,10 @@ def difficulty(self) -> int:
     def gas_limit(self) -> int:
         return self.execution_context.gas_limit
 
+    @property
+    def base_fee(self) -> int:
+        raise NotImplementedError("Basefee opcode is not implemented prior to London hard fork")
+
     def get_tip(self, transaction: SignedTransactionAPI) -> int:
         return transaction.gas_price
 

newsfragments/2015.feature.rst

@@ -0,0 +1 @@
+Add basefee opcode per EIP-3198

tests/core/opcodes/test_opcodes.py

@@ -160,6 +160,15 @@ def test_add(vm_class, val1, val2, expected):
     assert result == expected
 
 
+def test_base_fee():
+    computation = run_general_computation(LondonVM)
+    computation.opcodes[opcode_values.BASEFEE](computation)
+
+    result = computation.stack_pop1_any()
+
+    assert result == 10 ** 9  # 1 gwei
+
+
 @pytest.mark.parametrize(
     'opcode_value, expected',
     (