diff --git a/vyper/venom/basicblock.py b/vyper/venom/basicblock.py
index 57c8a13a99..cf6c7f10a5 100644
--- a/vyper/venom/basicblock.py
+++ b/vyper/venom/basicblock.py
@@ -259,6 +259,12 @@ def is_pseudo(self) -> bool:
         """
         return self.is_phi or self.is_param
 
+    def get_read_effects(self):
+        return effects.reads.get(self.opcode, effects.EMPTY)
+
+    def get_write_effects(self):
+        return effects.writes.get(self.opcode, effects.EMPTY)
+
     def get_label_operands(self) -> Iterator[IRLabel]:
         """
         Get all labels in instruction.
diff --git a/vyper/venom/effects.py b/vyper/venom/effects.py
index 9198cbe16d..b018357898 100644
--- a/vyper/venom/effects.py
+++ b/vyper/venom/effects.py
@@ -1,48 +1,59 @@
-_ALL = ("storage", "transient", "memory", "immutables", "balance", "returndata")
+from enum import Flag, auto
 
-_writes = {
-    "sstore": "storage",
-    "tstore": "transient",
-    "mstore": "memory",
-    "istore": "immutables",
-    "call": _ALL,
-    "delegatecall": _ALL,
-    "staticcall": "memory",
-    "create": _ALL,
-    "create2": _ALL,
-    "invoke": _ALL,  # could be smarter, look up the effects of the invoked function
-    "dloadbytes": "memory",
-    "returndatacopy": "memory",
-    "calldatacopy": "memory",
-    "codecopy": "memory",
-    "extcodecopy": "memory",
-    "mcopy": "memory",
-}
-_reads = {
-    "sload": "storage",
-    "tload": "transient",
-    "iload": "immutables",
-    "mload": "memory",
-    "mcopy": "memory",
-    "call": _ALL,
-    "delegatecall": _ALL,
-    "staticcall": _ALL,
-    "returndatasize": "returndata",
-    "returndatacopy": "returndata",
-    "balance": "balance",
-    "selfbalance": "balance",
-    "log": "memory",
-    "revert": "memory",
-    "return": "memory",
-    "sha3": "memory",
-}
+
+class Effects(Flag):
+    STORAGE = auto()
+    TRANSIENT = auto()
+    MEMORY = auto()
+    IMMUTABLES = auto()
+    BALANCE = auto()
+    RETURNDATA = auto()
 
 
-def _mktuple(x):
-    if not isinstance(x, tuple):
-        x = (x,)
-    return x
+EMPTY = Effects(0)
+ALL = ~EMPTY
+STORAGE = Effects.STORAGE
+TRANSIENT = Effects.TRANSIENT
+MEMORY = Effects.MEMORY
+IMMUTABLES = Effects.IMMUTABLES
+BALANCE = Effects.BALANCE
+RETURNDATA = Effects.RETURNDATA
 
 
-writes = {k: _mktuple(v) for k, v in _writes.items()}
-reads = {k: _mktuple(v) for k, v in _reads.items()}
\ No newline at end of file
+writes = {
+    "sstore": STORAGE,
+    "tstore": TRANSIENT,
+    "mstore": MEMORY,
+    "istore": IMMUTABLES,
+    "call": ALL,
+    "delegatecall": ALL,
+    "staticcall": MEMORY | RETURNDATA,
+    "create": ALL,
+    "create2": ALL,
+    "invoke": ALL,  # could be smarter, look up the effects of the invoked function
+    "dloadbytes": MEMORY,
+    "returndatacopy": MEMORY,
+    "calldatacopy": MEMORY,
+    "codecopy": MEMORY,
+    "extcodecopy": MEMORY,
+    "mcopy": MEMORY,
+}
+
+reads = {
+    "sload": STORAGE,
+    "tload": TRANSIENT,
+    "iload": IMMUTABLES,
+    "mload": MEMORY,
+    "mcopy": MEMORY,
+    "call": ALL,
+    "delegatecall": ALL,
+    "staticcall": ALL,
+    "returndatasize": RETURNDATA,
+    "returndatacopy": RETURNDATA,
+    "balance": BALANCE,
+    "selfbalance": BALANCE,
+    "log": MEMORY,
+    "revert": MEMORY,
+    "return": MEMORY,
+    "sha3": MEMORY,
+}