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Implement SAR opcode for Constantinople
Closes #1104
1 parent bf1d3c2 commit c7a1baf

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6 files changed

+136
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6 files changed

+136
-0
lines changed

‎eth/constants.py

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Original file line numberDiff line numberDiff line change
@@ -13,6 +13,7 @@
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UINT_256_CEILING = 2**256
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UINT_255_MAX = 2**255 - 1
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UINT_255_CEILING = 2**255
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UINT_255_NEGATIVE_ONE = -1 + UINT_256_CEILING
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NULL_BYTE = b'\x00'
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EMPTY_WORD = NULL_BYTE * 32
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‎eth/vm/forks/constantinople/opcodes.py

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@@ -32,6 +32,11 @@
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mnemonic=mnemonics.SHR,
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gas_cost=constants.GAS_VERYLOW,
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),
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opcode_values.SAR: as_opcode(
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logic_fn=arithmetic.sar,
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mnemonic=mnemonics.SAR,
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gas_cost=constants.GAS_VERYLOW,
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),
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}
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CONSTANTINOPLE_OPCODES = merge(

‎eth/vm/logic/arithmetic.py

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Original file line numberDiff line numberDiff line change
@@ -205,3 +205,18 @@ def shr(computation):
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result = (value >> shift_length) & constants.UINT_256_MAX
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computation.stack_push(result)
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def sar(computation):
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"""
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Arithmetic bitwise right shift
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"""
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shift_length, value = computation.stack_pop(num_items=2, type_hint=constants.UINT256)
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value = unsigned_to_signed(value)
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if shift_length >= 256:
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result = 0 if value >= 0 else constants.UINT_255_NEGATIVE_ONE
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else:
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result = (value >> shift_length) & constants.UINT_256_MAX
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computation.stack_push(result)

‎eth/vm/mnemonics.py

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Original file line numberDiff line numberDiff line change
@@ -15,6 +15,7 @@
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SIGNEXTEND = 'SIGNEXTEND'
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SHL = 'SHL'
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SHR = 'SHR'
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SAR = 'SAR'
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#
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# Comparisons
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#

‎eth/vm/opcode_values.py

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Original file line numberDiff line numberDiff line change
@@ -31,6 +31,7 @@
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BYTE = 0x1a
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SHL = 0x1b
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SHR = 0x1c
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SAR = 0x1d
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#

‎tests/core/opcodes/test_opcodes.py

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Original file line numberDiff line numberDiff line change
@@ -265,3 +265,116 @@ def test_shr(vm_class, val1, val2, expected):
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result = computation.stack_pop(type_hint=constants.UINT256)
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assert encode_hex(pad32(int_to_big_endian(result))) == expected
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@pytest.mark.parametrize(
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# EIP: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-145.md#sar-arithmetic-shift-right
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'vm_class, val1, val2, expected',
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(
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(
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ConstantinopleVM,
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'0x0000000000000000000000000000000000000000000000000000000000000001',
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'0x00',
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'0x0000000000000000000000000000000000000000000000000000000000000001',
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),
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(
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ConstantinopleVM,
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'0x0000000000000000000000000000000000000000000000000000000000000001',
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'0x01',
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'0x0000000000000000000000000000000000000000000000000000000000000000',
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),
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(
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ConstantinopleVM,
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'0x8000000000000000000000000000000000000000000000000000000000000000',
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'0x01',
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'0xc000000000000000000000000000000000000000000000000000000000000000',
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),
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(
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ConstantinopleVM,
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'0x8000000000000000000000000000000000000000000000000000000000000000',
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'0xff',
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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),
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(
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ConstantinopleVM,
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'0x8000000000000000000000000000000000000000000000000000000000000000',
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'0x0100',
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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),
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(
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ConstantinopleVM,
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'0x8000000000000000000000000000000000000000000000000000000000000000',
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'0x0101',
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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),
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(
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ConstantinopleVM,
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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'0x00',
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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),
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(
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ConstantinopleVM,
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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'0x01',
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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),
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(
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ConstantinopleVM,
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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'0xff',
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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),
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(
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ConstantinopleVM,
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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'0x0100',
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'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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),
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(
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ConstantinopleVM,
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'0x0000000000000000000000000000000000000000000000000000000000000000',
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'0x01',
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'0x0000000000000000000000000000000000000000000000000000000000000000',
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),
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(
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ConstantinopleVM,
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'0x4000000000000000000000000000000000000000000000000000000000000000',
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'0xfe',
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'0x0000000000000000000000000000000000000000000000000000000000000001',
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),
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(
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ConstantinopleVM,
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'0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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'0xf8',
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'0x000000000000000000000000000000000000000000000000000000000000007f',
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),
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(
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ConstantinopleVM,
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'0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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'0xfe',
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'0x0000000000000000000000000000000000000000000000000000000000000001',
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),
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(
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ConstantinopleVM,
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'0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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'0xff',
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'0x0000000000000000000000000000000000000000000000000000000000000000',
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),
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(
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ConstantinopleVM,
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'0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff',
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'0x0100',
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'0x0000000000000000000000000000000000000000000000000000000000000000',
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),
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)
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)
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def test_sar(vm_class, val1, val2, expected):
374+
computation = prepare_computation(vm_class)
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computation.stack_push(decode_hex(val1))
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computation.stack_push(decode_hex(val2))
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computation.opcodes[opcode_values.SAR](computation)
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result = computation.stack_pop(type_hint=constants.UINT256)
380+
assert encode_hex(pad32(int_to_big_endian(result))) == expected

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