Improve state variable SSA conversion

WIP of data dependency based on SSA

slither/analyses/data_depencency/data_depency.py

@@ -0,0 +1,105 @@
+"""
+    Compute the data depenency between all the SSA variables
+"""
+from slither.slithir.operations import Index, Member, OperationWithLValue
+from slither.slithir.variables import ReferenceVariable, Constant
+from slither.slithir.variables import (Constant, LocalIRVariable, StateIRVariable,
+                                       ReferenceVariable, TemporaryVariable,
+                                       TupleVariable)
+
+KEY = "DATA_DEPENDENCY_SSA"
+KEY_NON_SSA = "DATA_DEPENDENCY"
+
+def compute_dependency(slither):
+    for contract in slither.contracts:
+        compute_dependency_contract(contract)
+
+def compute_dependency_contract(contract):
+    if KEY in contract.context:
+        return
+
+    contract.context[KEY] = dict()
+    for function in contract.all_functions_called:
+        compute_dependency_function(function)
+        data_depencencies = function.context[KEY]
+ 
+        for (key, values) in data_depencencies.items():
+            if not key in contract.context[KEY]:
+                contract.context[KEY][key] = set(values)
+            else:
+                contract.context[KEY][key].union(values)
+
+    # transitive closure
+    changed = True
+    while changed:
+        changed = False
+        # Need to create new set() as its changed during iteration
+        data_depencencies = {k: set([v for v in values]) for k, values in  contract.context[KEY].items()}
+        for key, items in data_depencencies.items():
+            for item in items:
+                if item in data_depencencies:
+                    additional_items = contract.context[KEY][item]
+                    for additional_item in additional_items:
+                        if not additional_item in items and additional_item != key:
+                            changed = True
+                            contract.context[KEY][key].add(additional_item)
+
+
+    contract.context[KEY_NON_SSA] = convert_to_non_ssa(contract.context[KEY])
+
+
+
+def compute_dependency_function(function):
+    if KEY in function.context:
+        return function.context[KEY]
+
+    function.context[KEY] = dict()
+    for node in function.nodes:
+        for ir in node.irs_ssa:
+            if isinstance(ir, OperationWithLValue) and ir.lvalue:
+                lvalue = ir.lvalue
+               # if isinstance(ir.lvalue, ReferenceVariable):
+               #     lvalue = lvalue.points_to_origin
+               #     # TODO fix incorrect points_to for BALANCE
+               #     if not lvalue:
+               #         continue
+                if not lvalue in function.context[KEY]:
+                    function.context[KEY][lvalue] = set()
+                if isinstance(ir, Index):
+                    read = [ir.variable_left]
+                else:
+                    read = ir.read
+                [function.context[KEY][lvalue].add(v) for v in read if not isinstance(v, Constant)]
+
+    function.context[KEY_NON_SSA] = convert_to_non_ssa(function.context[KEY])
+
+def valid_non_ssa(v):
+    if isinstance(v, (TemporaryVariable,
+                      ReferenceVariable,
+                      TupleVariable)):
+        return False
+    return True
+
+def convert_variable_to_non_ssa(v):
+    if isinstance(v, (LocalIRVariable, StateIRVariable)):
+        if isinstance(v, LocalIRVariable):
+            function = v.function
+            return function.get_local_variable_from_name(v.name)
+        else:
+            contract = v.contract
+            return contract.get_state_variable_from_name(v.name)
+    return v
+
+def convert_to_non_ssa(data_depencies):
+    # Need to create new set() as its changed during iteration
+    ret = dict()
+    for (k, values) in data_depencies.items():
+        if not valid_non_ssa(k):
+            continue
+        var = convert_variable_to_non_ssa(k)
+        if not var in ret:
+            ret[var] = set()
+        ret[var] = ret[var].union(set([convert_variable_to_non_ssa(v) for v in
+                                       values if valid_non_ssa(v)]))
+
+    return ret

slither/slithir/operations/init_array.py

@@ -21,18 +21,19 @@ class InitArray(OperationWithLValue):
         self._init_values = init_values
         self._lvalue = lvalue
 
+    # if array inside the init values
+    def _unroll(self, l):
+        ret = []
+        for x in l:
+            if not isinstance(x, list):
+                ret += [x]
+            else:
+                ret += self._unroll(x)
+        return ret
+
     @property
     def read(self):
-        # if array inside the init values
-        def unroll(l):
-            ret = []
-            for x in l:
-                if not isinstance(x, list):
-                    ret += [x]
-                else:
-                    ret += unroll(x)
-            return ret
-        return unroll(self.init_values)
+        return self._unroll(self.init_values)
 
     @property
     def init_values(self):

slither/slithir/operations/phi.py

@@ -21,9 +21,18 @@ class Phi(OperationWithLValue):
         self._rvalues = []
         self._nodes = nodes
 
+    def _unroll(self, l):
+        ret = []
+        for x in l:
+            if not isinstance(x, list):
+                ret += [x]
+            else:
+                ret += self._unroll(x)
+        return ret
+
     @property
     def read(self):
-        return [self.rvalues]
+        return self.rvalues
 
     @property
     def rvalues(self):

slither/slithir/utils/ssa.py

@@ -42,13 +42,12 @@ def transform_slithir_vars_to_ssa(function):
     for idx in range(len(tuple_variables)):
         tuple_variables[idx].index = idx
 
-def add_ssa_ir(function, all_state_variables_instances, all_state_variables_written):
+def add_ssa_ir(function, all_state_variables_instances):
     '''
         Add SSA version of the IR
     Args:
         function
         all_state_variables_instances
-        all_state_variables_written (set(str)): canonical name of all the state variables written
     '''
 
     if not function.is_implemented:
@@ -106,6 +105,12 @@ def add_ssa_ir(function, all_state_variables_instances, all_state_variables_writ
                      all_state_variables_instances,
                      init_local_variables_instances,
                      [])
+    fix_phi_rvalues_and_storage_ref(function.entry_point,
+                     dict(init_local_variables_instances),
+                     all_init_local_variables_instances,
+                     dict(init_state_variables_instances),
+                     all_state_variables_instances,
+                     init_local_variables_instances)
 
 
 def last_name(n, var, init_vars):
@@ -188,7 +193,7 @@ def generate_ssa_irs(node, local_variables_instances, all_local_variables_instan
     if node in visited:
         return
 
-    if node.fathers and any(not father in visited for father in node.fathers):
+    if node.type in [NodeType.ENDIF, NodeType.ENDLOOP] and any(not father in visited for father in node.fathers):
         return
 
     # visited is shared
@@ -203,8 +208,14 @@ def generate_ssa_irs(node, local_variables_instances, all_local_variables_instan
         assert isinstance(ir, Phi)
         update_lvalue(ir, node, local_variables_instances, all_local_variables_instances, state_variables_instances, all_state_variables_instances)
 
+
+    # these variables are lived only during the liveness of the block
+    # They dont need phi function
+    temporary_variables_instances = dict()
+    reference_variables_instances = dict()
+
     for ir in node.irs:
-        new_ir = copy_ir(ir, local_variables_instances, state_variables_instances)
+        new_ir = copy_ir(ir, local_variables_instances, state_variables_instances, temporary_variables_instances, reference_variables_instances)
         update_lvalue(new_ir, node, local_variables_instances, all_local_variables_instances, state_variables_instances, all_state_variables_instances)
 
         if new_ir:
@@ -233,6 +244,14 @@ def generate_ssa_irs(node, local_variables_instances, all_local_variables_instan
                         else:
                             new_ir.lvalue.add_points_to(new_ir.rvalue)
 
+
+    for succ in node.dominator_successors:
+        generate_ssa_irs(succ, dict(local_variables_instances), all_local_variables_instances, dict(state_variables_instances), all_state_variables_instances, init_local_variables_instances, visited)
+
+    for dominated in node.dominance_frontier:
+        generate_ssa_irs(dominated, dict(local_variables_instances), all_local_variables_instances, dict(state_variables_instances), all_state_variables_instances, init_local_variables_instances, visited)
+
+def fix_phi_rvalues_and_storage_ref(node, local_variables_instances, all_local_variables_instances, state_variables_instances, all_state_variables_instances, init_local_variables_instances):
     for ir in node.irs_ssa:
         if isinstance(ir, (Phi)) and not ir.rvalues:
             variables = [last_name(dst, ir.lvalue, init_local_variables_instances) for dst in ir.nodes]
@@ -255,13 +274,10 @@ def generate_ssa_irs(node, local_variables_instances, all_local_variables_instan
                             phi_ir.rvalues = [origin]
                             node.add_ssa_ir(phi_ir)
                             update_lvalue(phi_ir, node, local_variables_instances, all_local_variables_instances, state_variables_instances, all_state_variables_instances)
-
-
     for succ in node.dominator_successors:
-        generate_ssa_irs(succ, dict(local_variables_instances), all_local_variables_instances, dict(state_variables_instances), all_state_variables_instances, init_local_variables_instances, visited)
+        fix_phi_rvalues_and_storage_ref(succ, dict(local_variables_instances), all_local_variables_instances, dict(state_variables_instances), all_state_variables_instances, init_local_variables_instances)
+
 
-    for dominated in node.dominance_frontier:
-        generate_ssa_irs(dominated, dict(local_variables_instances), all_local_variables_instances, dict(state_variables_instances), all_state_variables_instances, init_local_variables_instances, visited)
 
 def add_phi_origins(node, local_variables_definition, state_variables_definition):
 
@@ -294,11 +310,16 @@ def add_phi_origins(node, local_variables_definition, state_variables_definition
     for succ in node.dominator_successors:
         add_phi_origins(succ, local_variables_definition, state_variables_definition)
 
-def copy_ir(ir, local_variables_instances, state_variables_instances):
+def copy_ir(ir, local_variables_instances, state_variables_instances, temporary_variables_instances, reference_variables_instances):
     '''
     Args:
         ir (Operation)
-        variables_instances(dict(str -> Variable))
+        local_variables_instances(dict(str -> LocalVariable))
+        state_variables_instances(dict(str -> StateVariable))
+        temporary_variables_instances(dict(int -> Variable))
+        reference_variables_instances(dict(int -> Variable))
+
+    Note: temporary and reference can be indexed by int, as they dont need phi functions
     '''
 
     def get(variable):
@@ -307,15 +328,19 @@ def copy_ir(ir, local_variables_instances, state_variables_instances):
         if isinstance(variable, StateVariable) and variable.canonical_name in state_variables_instances:
             return state_variables_instances[variable.canonical_name]
         elif isinstance(variable, ReferenceVariable):
-            new_variable = ReferenceVariable(variable.node, index=variable.index)
-            if variable.points_to:
-                new_variable.points_to = get(variable.points_to)
-            new_variable.set_type(variable.type)
-            return new_variable
+            if not variable.index in reference_variables_instances:
+                new_variable = ReferenceVariable(variable.node, index=variable.index)
+                if variable.points_to:
+                    new_variable.points_to = get(variable.points_to)
+                new_variable.set_type(variable.type)
+                reference_variables_instances[variable.index] = new_variable
+            return reference_variables_instances[variable.index]
         elif isinstance(variable, TemporaryVariable):
-            new_variable = TemporaryVariable(variable.node, index=variable.index)
-            new_variable.set_type(variable.type)
-            return new_variable
+            if not variable.index in temporary_variables_instances:
+                new_variable = TemporaryVariable(variable.node, index=variable.index)
+                new_variable.set_type(variable.type)
+                temporary_variables_instances[variable.index] = new_variable
+            return temporary_variables_instances[variable.index]
         return variable
 
     def get_variable(ir, f):

slither/slithir/variables/local_variable.py

@@ -58,4 +58,4 @@ class LocalIRVariable(LocalVariable, SlithIRVariable):
             return '{}_{} (-> {})'.format(self._name,
                                              self.index,
                                              [v.name for v in self.points_to])
-        return '{}_{} ({})'.format(self._name, self.index, self.location)
+        return '{}_{}'.format(self._name, self.index)

slither/solc_parsing/declarations/contract.py

@@ -355,7 +355,6 @@ class ContractSolc04(Contract):
                 func.generate_slithir_and_analyze()
 
         all_ssa_state_variables_instances = dict()
-        all_state_variables_written = {v.canonical_name for v in self.all_state_variables_written}
 
         for contract in self.inheritance:
             for v in contract.variables:
@@ -372,8 +371,7 @@ class ContractSolc04(Contract):
 
         for func in self.functions + self.modifiers:
             if func.contract == self:
-                func.generate_slithir_ssa(all_ssa_state_variables_instances,
-                                          all_state_variables_written)
+                func.generate_slithir_ssa(all_ssa_state_variables_instances)
 
     def fix_phi(self):
         last_state_variables_instances = dict()

slither/solc_parsing/declarations/function.py

@@ -909,11 +909,11 @@ class FunctionSolc(Function):
         self._analyze_read_write()
         self._analyze_calls()
 
-    def generate_slithir_ssa(self, all_ssa_state_variables_instances, all_written_state_variables):
+    def generate_slithir_ssa(self, all_ssa_state_variables_instances):
         compute_dominators(self.nodes)
         compute_dominance_frontier(self.nodes)
         transform_slithir_vars_to_ssa(self)
-        add_ssa_ir(self, all_ssa_state_variables_instances, all_written_state_variables)
+        add_ssa_ir(self, all_ssa_state_variables_instances)
 
     def update_read_write_using_ssa(self):
         for node in self.nodes:

slither/solc_parsing/slitherSolc.py

@@ -9,6 +9,7 @@ from slither.solc_parsing.declarations.contract import ContractSolc04
 from slither.core.slither_core import Slither
 from slither.core.declarations.pragma_directive import Pragma
 from slither.core.declarations.import_directive import Import
+from slither.analyses.data_depencency.data_depency import compute_dependency
 
 class SlitherSolc(Slither):
 
@@ -190,6 +191,8 @@ class SlitherSolc(Slither):
 
         self._convert_to_slithir()
 
+        compute_dependency(self)
+
     # TODO refactor the following functions, and use a lambda function
 
     @property
@@ -317,3 +320,4 @@ class SlitherSolc(Slither):
             contract.fix_phi()
             contract.update_read_write_using_ssa()
 
+