Merge pull request #1984 from Tiko7454/dominator-deadcode-problem-fix

Dominator deadcode problem fix

slither/core/cfg/node.py

@@ -194,6 +194,8 @@ def __init__(
         self.file_scope: "FileScope" = file_scope
         self._function: Optional["Function"] = None
 
+        self._is_reachable: bool = False
+
     ###################################################################################
     ###################################################################################
     # region General's properties
@@ -235,6 +237,13 @@ def set_function(self, function: "Function") -> None:
     def function(self) -> "Function":
         return self._function
 
+    @property
+    def is_reachable(self) -> bool:
+        return self._is_reachable
+
+    def set_is_reachable(self, new_is_reachable: bool) -> None:
+        self._is_reachable = new_is_reachable
+
     # endregion
     ###################################################################################
     ###################################################################################

slither/core/dominators/utils.py

@@ -9,9 +9,16 @@
 def intersection_predecessor(node: "Node") -> Set["Node"]:
     if not node.fathers:
         return set()
-    ret = node.fathers[0].dominators
-    for pred in node.fathers[1:]:
-        ret = ret.intersection(pred.dominators)
+    if not any(father.is_reachable for father in node.fathers):
+        return set()
+
+    ret = set()
+    for pred in node.fathers:
+        ret = ret.union(pred.dominators)
+
+    for pred in node.fathers:
+        if pred.is_reachable:
+            ret = ret.intersection(pred.dominators)
     return ret
 
 
@@ -84,6 +91,8 @@ def compute_dominance_frontier(nodes: List["Node"]) -> None:
     for node in nodes:
         if len(node.fathers) >= 2:
             for father in node.fathers:
+                if not father.is_reachable:
+                    continue
                 runner = father
                 # Corner case: if there is a if without else
                 # we need to add update the conditional node

slither/solc_parsing/declarations/function.py

@@ -315,6 +315,9 @@ def analyze_content(self) -> None:
 
         self._remove_alone_endif()
 
+        if self._function.entry_point:
+            self._update_reachability(self._function.entry_point)
+
     # endregion
     ###################################################################################
     ###################################################################################
@@ -1102,6 +1105,13 @@ def _parse_unchecked_block(self, block: Dict, node: NodeSolc, scope):
             node = self._parse_statement(statement, node, new_scope)
         return node
 
+    def _update_reachability(self, node: Node) -> None:
+        if node.is_reachable:
+            return
+        node.set_is_reachable(True)
+        for son in node.sons:
+            self._update_reachability(son)
+
     def _parse_cfg(self, cfg: Dict) -> None:
 
         assert cfg[self.get_key()] == "Block"