mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
40 lines
972 B
Python
40 lines
972 B
Python
from rule import Rule
|
|
from opcodes import *
|
|
from util import *
|
|
|
|
"""
|
|
Overflow checked signed integer addition.
|
|
"""
|
|
|
|
n_bits = 256
|
|
type_bits = 8
|
|
|
|
while type_bits <= n_bits:
|
|
|
|
rule = Rule()
|
|
|
|
# Input vars
|
|
X_short = BitVec('X', type_bits)
|
|
Y_short = BitVec('Y', type_bits)
|
|
|
|
# Z3's overflow and underflow conditions
|
|
actual_overflow = Not(BVAddNoOverflow(X_short, Y_short, True))
|
|
actual_underflow = Not(BVAddNoUnderflow(X_short, Y_short))
|
|
|
|
# cast to full n_bits values
|
|
X = BVSignedUpCast(X_short, n_bits)
|
|
Y = BVSignedUpCast(Y_short, n_bits)
|
|
|
|
# Constants
|
|
maxValue = BVSignedMax(type_bits, n_bits)
|
|
minValue = BVSignedMin(type_bits, n_bits)
|
|
|
|
# Overflow and underflow checks in YulUtilFunction::overflowCheckedIntAddFunction
|
|
overflow_check = AND(ISZERO(SLT(X, 0)), SGT(Y, SUB(maxValue, X)))
|
|
underflow_check = AND(SLT(X, 0), SLT(Y, SUB(minValue, X)))
|
|
|
|
rule.check(actual_overflow, overflow_check != 0)
|
|
rule.check(actual_underflow, underflow_check != 0)
|
|
|
|
type_bits *= 2
|