optimize EVM memory extend

nimbus/evm/memory.nim

@@ -28,11 +28,10 @@ proc len*(memory: Memory): int =
 proc extend*(memory: var Memory; startPos: Natural; size: Natural) =
  if size == 0:
  return
- var newSize = ceil32(startPos + size)
+ let newSize = ceil32(startPos + size)
  if newSize <= len(memory):
  return
- var sizeToExtend = newSize - len(memory)
- memory.bytes = memory.bytes.concat(repeat(0.byte, sizeToExtend))
+ memory.bytes.setLen(newSize)
 
 proc newMemory*(size: Natural): Memory =
  result = newMemory()
@@ -51,9 +50,6 @@ proc write*(memory: var Memory, startPos: Natural, value: openArray[byte]) =
  let size = value.len
  if size == 0:
  return
- validateLte(startPos + size, memory.len)
- if memory.len < startPos + size:
- memory.bytes = memory.bytes.concat(repeat(0.byte, memory.len - (startPos + size))) # TODO: better logarithmic scaling?
-
+ validateLte(startPos + size, memory.len) 
  for z, b in value:
  memory.bytes[z + startPos] = b

nimbus/evm/validation.nim

@@ -34,6 +34,11 @@ proc validateLt*(value: UInt256 | int, maximum: int, title: string = "Value") =
  raise newException(ValidationError,
  &"{title} {value} is not less than {maximum}")
 
+proc validateLte*(value: int, maximum: int, title: string = "Value") =
+ if value > maximum:
+ raise newException(ValidationError,
+ &"{title} {value} is not less or equal to {maximum}")
+
 proc validateStackItem*(value: string) =
  if value.len > 32:
  raise newException(ValidationError,