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fix: bitwise opcode semantics #196

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merged 3 commits into from
Sep 20, 2023
Merged

fix: bitwise opcode semantics #196

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b92172d
fix xor semantics
daejunpark Sep 19, 2023
773000a
fix not semantics
daejunpark Sep 20, 2023
77c8076
cleanup
daejunpark Sep 20, 2023
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43 changes: 19 additions & 24 deletions src/halmos/sevm.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1227,31 +1227,31 @@ def is_zero(x: Word) -> Word:
return test(x, False)


def and_or(x: Word, y: Word, is_and: bool) -> Word:
def bitwise(op, x: Word, y: Word) -> Word:
if is_bool(x) and is_bool(y):
if is_and:
if op == EVM.AND:
return And(x, y)
else:
elif op == EVM.OR:
return Or(x, y)
elif op == EVM.XOR:
return Xor(x, y)
else:
raise ValueError(op, x, y)
elif is_bv(x) and is_bv(y):
if is_and:
if op == EVM.AND:
return x & y
else:
elif op == EVM.OR:
return x | y
elif op == EVM.XOR:
return x ^ y # bvxor
else:
raise ValueError(op, x, y)
elif is_bool(x) and is_bv(y):
return and_or(If(x, con(1), con(0)), y, is_and)
return bitwise(op, If(x, con(1), con(0)), y)
elif is_bv(x) and is_bool(y):
return and_or(x, If(y, con(1), con(0)), is_and)
return bitwise(op, x, If(y, con(1), con(0)))
else:
raise ValueError(x, y, is_and)


def and_of(x: Word, y: Word) -> Word:
return and_or(x, y, True)


def or_of(x: Word, y: Word) -> Word:
return and_or(x, y, False)
raise ValueError(op, x, y)


def b2i(w: Word) -> Word:
Expand Down Expand Up @@ -2486,12 +2486,10 @@ def run(self, ex0: Exec) -> Tuple[List[Exec], Steps]:
elif opcode == EVM.ISZERO:
ex.st.push(is_zero(ex.st.pop()))

elif opcode == EVM.AND:
ex.st.push(and_of(ex.st.pop(), ex.st.pop()))
elif opcode == EVM.OR:
ex.st.push(or_of(ex.st.pop(), ex.st.pop()))
elif opcode in [EVM.AND, EVM.OR, EVM.XOR]:
ex.st.push(bitwise(opcode, ex.st.pop(), ex.st.pop()))
elif opcode == EVM.NOT:
ex.st.push(~ex.st.pop()) # bvnot
ex.st.push(~b2i(ex.st.pop())) # bvnot
elif opcode == EVM.SHL:
w = ex.st.pop()
ex.st.push(b2i(ex.st.pop()) << b2i(w)) # bvshl
Expand All @@ -2508,9 +2506,6 @@ def run(self, ex0: Exec) -> Tuple[List[Exec], Steps]:
bl = (w + 1) * 8
ex.st.push(SignExt(256 - bl, Extract(bl - 1, 0, ex.st.pop())))

elif opcode == EVM.XOR:
ex.st.push(ex.st.pop() ^ ex.st.pop()) # bvxor

elif opcode == EVM.CALLDATALOAD:
if ex.calldata is None:
ex.st.push(f_calldataload(ex.st.pop()))
Expand Down