mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
43 lines
797 B
Python
43 lines
797 B
Python
from rule import Rule
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from opcodes import *
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"""
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Rule:
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1) SHL(A, SIGNEXTEND(B, X)) -> SIGNEXTEND(A / 8 + B, SHL(A, B))
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given A % 8 == 0 AND A / 8 + B >= B
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2) SIGNEXTEND(A, SHR(B, X)) -> SAR(B, X)
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given
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B % 8 == 0 AND
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A <= WordSize
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B <= wordSize
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(WordSize - B) / 8 == A + 1
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"""
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n_bits = 128
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# Input vars
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X = BitVec('X', n_bits)
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Y = BitVec('Y', n_bits)
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A = BitVec('A', n_bits)
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B = BitVec('B', n_bits)
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rule1 = Rule()
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rule1.require(A % 8 == 0)
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rule1.require(UGE(A / 8 + B, B))
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rule1.check(
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SHL(A, SIGNEXTEND(B, X)),
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SIGNEXTEND(A / 8 + B, SHL(A, X))
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)
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rule2 = Rule()
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rule2.require(B % 8 == 0)
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rule2.require(ULE(A, n_bits))
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rule2.require(ULE(B, n_bits))
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rule2.require((BitVecVal(n_bits, n_bits) - B) / 8 == A + 1)
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rule2.check(
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SIGNEXTEND(A, SHR(B, X)),
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SAR(B, X)
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)
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