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Use unique variable name for yul variable #648

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merged 2 commits into from
Sep 29, 2020
Merged

Use unique variable name for yul variable #648

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feabf0e
Add unique name for yul variable to prevent lookup issue (fix #647)
montyly Sep 29, 2020
05c2d1d
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montyly Sep 29, 2020
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24 changes: 21 additions & 3 deletions slither/solc_parsing/yul/parse_yul.py
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,21 @@ def link_underlying_nodes(node1: YulNode, node2: YulNode):
link_nodes(node1.underlying_node, node2.underlying_node)


def _name_to_yul_name(variable_name: str, yul_id: List[str]) -> str:
"""
Translate the variable name to a unique yul name
Within the same function, yul blocks can declare
different variables with the same name
We need to create unique name per variable
to prevent collision during the SSA generation

:param var:
:param yul_id:
:return:
"""
return variable_name + f"_{'_'.join(yul_id)}"


class YulScope(metaclass=abc.ABCMeta):
__slots__ = [
"_contract",
Expand Down Expand Up @@ -135,7 +150,11 @@ def add_yul_local_variable(self, var):

def get_yul_local_variable_from_name(self, variable_name):
return next(
(v for v in self._yul_local_variables if v.underlying.name == variable_name),
(
v
for v in self._yul_local_variables
if v.underlying.name == _name_to_yul_name(variable_name, self.id)
),
None,
)

Expand All @@ -162,7 +181,7 @@ def __init__(self, var: LocalVariable, root: YulScope, ast: Dict):
var.set_function(root.function)
var.set_offset(ast["src"], root.slither)

var.name = ast["name"]
var.name = _name_to_yul_name(ast["name"], root.id)
var.set_type(ElementaryType("uint256"))
var.set_location("memory")

Expand Down Expand Up @@ -516,7 +535,6 @@ def convert_yul_typed_name(root: YulScope, parent: YulNode, ast: Dict) -> YulNod
local_var = LocalVariable()

var = YulLocalVariable(local_var, root, ast)

root.add_yul_local_variable(var)

node = root.new_node(NodeType.VARIABLE, ast["src"])
Expand Down