feat[venom]: add effects to instructions (#4264)

this commit adds an `effects.py` file to venom, which describes
the effects of opcodes. this is useful for several ongoing efforts,
including CSE elimination and DFT pass improvements.

---------

Co-authored-by: Harry Kalogirou <harkal@nlogn.eu>
Co-authored-by: HodanPlodky <36966616+HodanPlodky@users.noreply.github.com>

vyper/venom/basicblock.py

@@ -1,5 +1,6 @@
 from typing import TYPE_CHECKING, Any, Iterator, Optional, Union
 
+import vyper.venom.effects as effects
 from vyper.codegen.ir_node import IRnode
 from vyper.utils import OrderedSet
 
@@ -238,6 +239,12 @@ def is_volatile(self) -> bool:
     def is_bb_terminator(self) -> bool:
         return self.opcode in BB_TERMINATORS
 
+    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.

vyper/venom/effects.py

@@ -0,0 +1,85 @@
+from enum import Flag, auto
+
+
+class Effects(Flag):
+    STORAGE = auto()
+    TRANSIENT = auto()
+    MEMORY = auto()
+    MSIZE = auto()
+    IMMUTABLES = auto()
+    RETURNDATA = auto()
+    LOG = auto()
+    BALANCE = auto()
+    EXTCODE = auto()
+
+
+EMPTY = Effects(0)
+ALL = ~EMPTY
+STORAGE = Effects.STORAGE
+TRANSIENT = Effects.TRANSIENT
+MEMORY = Effects.MEMORY
+MSIZE = Effects.MSIZE
+IMMUTABLES = Effects.IMMUTABLES
+RETURNDATA = Effects.RETURNDATA
+LOG = Effects.LOG
+BALANCE = Effects.BALANCE
+EXTCODE = Effects.EXTCODE
+
+
+_writes = {
+    "sstore": STORAGE,
+    "tstore": TRANSIENT,
+    "mstore": MEMORY,
+    "istore": IMMUTABLES,
+    "call": ALL ^ IMMUTABLES,
+    "delegatecall": ALL ^ IMMUTABLES,
+    "staticcall": MEMORY | RETURNDATA,
+    "create": ALL ^ (MEMORY | IMMUTABLES),
+    "create2": ALL ^ (MEMORY | IMMUTABLES),
+    "invoke": ALL,  # could be smarter, look up the effects of the invoked function
+    "log": LOG,
+    "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,
+    "create": ALL,
+    "create2": ALL,
+    "invoke": ALL,
+    "returndatasize": RETURNDATA,
+    "returndatacopy": RETURNDATA,
+    "balance": BALANCE,
+    "selfbalance": BALANCE,
+    "extcodecopy": EXTCODE,
+    "selfdestruct": BALANCE,  # may modify code, but after the transaction
+    "log": MEMORY,
+    "revert": MEMORY,
+    "return": MEMORY,
+    "sha3": MEMORY,
+    "msize": MSIZE,
+}
+
+reads = _reads.copy()
+writes = _writes.copy()
+
+for k, v in reads.items():
+    if MEMORY in v:
+        if k not in writes:
+            writes[k] = EMPTY
+        writes[k] |= MSIZE
+
+for k, v in writes.items():
+    if MEMORY in v:
+        writes[k] |= MSIZE