Add store_through_chain

pythonbpf/binary_ops.py

@@ -6,38 +6,57 @@ import logging
 logger: Logger = logging.getLogger(__name__)
 
 
-def recursive_dereferencer(var, builder):
-    """dereference until primitive type comes out"""
-    # TODO: Not worrying about stack overflow for now
+def deref_to_val(var, builder):
+    """Dereference a variable to get its value and pointer chain."""
     logger.info(f"Dereferencing {var}, type is {var.type}")
-    if isinstance(var.type, ir.PointerType):
-        a = builder.load(var)
-        return recursive_dereferencer(a, builder)
-    elif isinstance(var.type, ir.IntType):
-        return var
+
+    chain = [var]
+    cur = var
+
+    while isinstance(cur.type, ir.PointerType):
+        cur = builder.load(cur)
+        chain.append(cur)
+
+    if isinstance(cur.type, ir.IntType):
+        logger.info(f"dereference chain: {chain}")
+        return cur, chain
     else:
-        raise TypeError(f"Unsupported type for dereferencing: {var.type}")
+        raise TypeError(f"Unsupported type for dereferencing: {cur.type}")
 
 
 def get_operand_value(operand, builder, local_sym_tab):
     """Extract the value from an operand, handling variables and constants."""
     if isinstance(operand, ast.Name):
         if operand.id in local_sym_tab:
-            return recursive_dereferencer(local_sym_tab[operand.id].var, builder)
+            var = local_sym_tab[operand.id].var
+            val, chain = deref_to_val(var, builder)
+            return val, chain, var
         raise ValueError(f"Undefined variable: {operand.id}")
     elif isinstance(operand, ast.Constant):
         if isinstance(operand.value, int):
-            return ir.Constant(ir.IntType(64), operand.value)
+            cst = ir.Constant(ir.IntType(64), operand.value)
+            return cst, [cst], None
         raise TypeError(f"Unsupported constant type: {type(operand.value)}")
     elif isinstance(operand, ast.BinOp):
-        return handle_binary_op_impl(operand, builder, local_sym_tab)
+        res = handle_binary_op_impl(operand, builder, local_sym_tab)
+        return res, [res], None
     raise TypeError(f"Unsupported operand type: {type(operand)}")
 
 
+def store_through_chain(value, chain, builder):
+    """Store a value through a pointer chain."""
+    if not chain or len(chain) < 2:
+        raise ValueError("Pointer chain must have at least two elements")
+
+    for ptr in reversed(chain[1:]):
+        builder.store(value, ptr)
+        value = ptr
+
+
 def handle_binary_op_impl(rval, builder, local_sym_tab):
     op = rval.op
-    left = get_operand_value(rval.left, builder, local_sym_tab)
-    right = get_operand_value(rval.right, builder, local_sym_tab)
+    left, _, _ = get_operand_value(rval.left, builder, local_sym_tab)
+    right, _, _ = get_operand_value(rval.right, builder, local_sym_tab)
     logger.info(f"left is {left}, right is {right}, op is {op}")
 
     # Map AST operation nodes to LLVM IR builder methods