ir: IRAssignable: track writers

compiler/ir.py

@@ -112,7 +112,16 @@ class IRVoid(IRValue):
 
 
 class IRAssignable(IRValue, metaclass=abc.ABCMeta):
-    pass
+    def __init__(self, location: SourceLocation):
+        super().__init__(location)
+        self.writers: list[IRAction] = []
+
+    def __str__(self):
+        return self.codegen()
+
+    def __repr__(self) -> str:
+        return f"{self.codegen()} (readers: {repr([reader for reader in self.readers])}, " + \
+            f"writers: {repr([writer for writer in self.writers])})"
 
 
 class IRRegister(IRAssignable):