Small cleanup, read bytes when you know you'll need them

Author: lithp

eth/vm/computation.py

@@ -246,10 +246,16 @@ def memory_write(self, start_position: int, size: int, value: bytes) -> None:
 
     def memory_read(self, start_position: int, size: int) -> memoryview:
         """
-        Read and return ``size`` bytes from memory starting at ``start_position``.
+        Read and return a view of ``size`` bytes from memory starting at ``start_position``.
         """
         return self._memory.read(start_position, size)
 
+    def memory_read_bytes(self, start_position: int, size: int) -> bytes:
+        """
+        Read and return ``size`` bytes from memory starting at ``start_position``.
+        """
+        return self._memory.read_bytes(start_position, size)
+
     #
     # Gas Consumption
     #
@@ -447,12 +453,11 @@ def add_log_entry(
             self,
             account: Address,
             topics: List[int],
-            data: Union[bytes, memoryview]) -> None:
+            data: bytes) -> None:
         validate_canonical_address(account, title="Log entry address")
         for topic in topics:
             validate_uint256(topic, title="Log entry topic")
-        validate_is_bytes_or_view(data, title="Log entry data")
-        data = bytes(data)
+        validate_is_bytes(data, title="Log entry data")
         self._log_entries.append(
             (self.transaction_context.get_next_log_counter(), account, topics, data))
 

eth/vm/logic/logging.py

@@ -30,7 +30,7 @@ def log_XX(computation: BaseComputation, topic_count: int) -> None:
     )
 
     computation.extend_memory(mem_start_position, size)
-    log_data = computation.memory_read(mem_start_position, size)
+    log_data = computation.memory_read_bytes(mem_start_position, size)
 
     computation.add_log_entry(
         account=computation.msg.storage_address,

eth/vm/logic/memory.py

@@ -32,8 +32,8 @@ def mload(computation: BaseComputation) -> None:
 
     computation.extend_memory(start_position, 32)
 
-    value = computation.memory_read(start_position, 32)
-    computation.stack_push(bytes(value))
+    value = computation.memory_read_bytes(start_position, 32)
+    computation.stack_push(value)
 
 
 def msize(computation: BaseComputation) -> None:

eth/vm/logic/sha3.py

@@ -12,12 +12,12 @@ def sha3(computation: BaseComputation) -> None:
 
     computation.extend_memory(start_position, size)
 
-    sha3_bytes = computation.memory_read(start_position, size)
+    sha3_bytes = computation.memory_read_bytes(start_position, size)
     word_count = ceil32(len(sha3_bytes)) // 32
 
     gas_cost = constants.GAS_SHA3WORD * word_count
     computation.consume_gas(gas_cost, reason="SHA3: word gas cost")
 
-    result = keccak(bytes(sha3_bytes))
+    result = keccak(sha3_bytes)
 
     computation.stack_push(result)

eth/vm/logic/system.py

@@ -32,8 +32,7 @@ def return_op(computation: BaseComputation) -> None:
 
     computation.extend_memory(start_position, size)
 
-    output = computation.memory_read(start_position, size)
-    computation.output = bytes(output)
+    computation.output = computation.memory_read_bytes(start_position, size)
     raise Halt('RETURN')
 
 
@@ -42,8 +41,7 @@ def revert(computation: BaseComputation) -> None:
 
     computation.extend_memory(start_position, size)
 
-    output = computation.memory_read(start_position, size)
-    computation.output = bytes(output)
+    computation.output = computation.memory_read_bytes(start_position, size)
     raise Revert(computation.output)
 
 
@@ -163,8 +161,8 @@ def __call__(self, computation: BaseComputation) -> None:
             computation.stack_push(0)
             return
 
-        call_data = bytes(
-            computation.memory_read(stack_data.memory_start, stack_data.memory_length)
+        call_data = computation.memory_read_bytes(
+            stack_data.memory_start, stack_data.memory_length
         )
 
         create_msg_gas = self.max_child_gas_modifier(

eth/vm/memory.py

@@ -61,8 +61,14 @@ def write(self, start_position: int, size: int, value: bytes) -> None:
             for idx, v in enumerate(value):
                 self._bytes[start_position + idx] = v
 
-    def read(self, start_position: int, size: int) -> Union[bytes, memoryview]:
+    def read(self, start_position: int, size: int) -> memoryview:
         """
-        Read a value from memory.
+        Return a view into the memory
         """
         return memoryview(self._bytes)[start_position:start_position + size]
+
+    def read_bytes(self, start_position: int, size: int) -> bytes:
+        """
+        Read a value from memory and return a fresh bytes instance
+        """
+        return bytes(self._bytes[start_position:start_position + size])