solidity/test/formal/combine_byte_shl.py
2020-07-08 20:26:46 +02:00

30 lines
447 B
Python

from rule import Rule
from opcodes import *
"""
byte(A, shl(B, X))
given B % 8 == 0 && A <= 32 && B <= 256
->
byte(A + B / 8, X)
"""
rule = Rule()
n_bits = 256
# Input vars
X = BitVec('X', n_bits)
A = BitVec('A', n_bits)
B = BitVec('B', n_bits)
# Non optimized result
nonopt = BYTE(A, SHL(B, X))
# Optimized result
opt = BYTE(A + B / 8, X)
rule.require(B % 8 == 0)
rule.require(ULE(A, 32))
rule.require(ULE(B, 256))
rule.check(nonopt, opt)