field check in allocation pass

Author: varun-r-mallya

pythonbpf/allocation_pass.py

@@ -337,13 +337,6 @@ def _allocate_for_attribute(builder, var_name, rval, local_sym_tab, structs_sym_
                 VmlinuxHandlerRegistry.get_field_type(vmlinux_struct_name, field_name)
             )
             field_ir, field = field_type
-            # TODO: For now, we only support integer type allocations.
-            # This always assumes first argument of function to be the context struct
-            # base_ptr = builder.function.args[0]
-            # local_sym_tab[
-            #     struct_var
-            # ].var = base_ptr  # This is repurposing of var to store the pointer of the base type
-            # local_sym_tab[struct_var].ir_type = field_ir
 
             # Determine the actual IR type based on the field's type
             actual_ir_type = None
@@ -398,12 +391,12 @@ def _allocate_for_attribute(builder, var_name, rval, local_sym_tab, structs_sym_
                 )
                 actual_ir_type = ir.IntType(64)
 
-            # Allocate with the actual IR type, not the GlobalVariable
+            # Allocate with the actual IR type
             var = _allocate_with_type(builder, var_name, actual_ir_type)
-            local_sym_tab[var_name] = LocalSymbol(var, actual_ir_type, field)
+            local_sym_tab[var_name] = LocalSymbol(var, actual_ir_type, field)  # <-- Store Field metadata
 
             logger.info(
-                f"Pre-allocated {var_name} from vmlinux struct {vmlinux_struct_name}.{field_name}"
+                f"Pre-allocated {var_name} as {actual_ir_type} from vmlinux struct {vmlinux_struct_name}.{field_name}"
             )
             return
         else:

pythonbpf/expr/expr_pass.py

@@ -14,6 +14,7 @@
 )
 from pythonbpf.vmlinux_parser.assignment_info import Field
 from .vmlinux_registry import VmlinuxHandlerRegistry
+from ..vmlinux_parser.dependency_node import Field
 
 logger: Logger = logging.getLogger(__name__)
 
@@ -89,8 +90,16 @@ def _handle_attribute_expr(
                     return vmlinux_result
                 else:
                     raise RuntimeError("Vmlinux struct did not process successfully")
-            metadata = structs_sym_tab[var_metadata]
-            if attr_name in metadata.fields:
+
+            elif isinstance(var_metadata, Field):
+                logger.error(
+                    f"Cannot access field '{attr_name}' on already-loaded field value '{var_name}'"
+                )
+                return None
+
+            # Regular user-defined struct
+            metadata = structs_sym_tab.get(var_metadata)
+            if metadata and attr_name in metadata.fields:
                 gep = metadata.gep(builder, var_ptr, attr_name)
                 val = builder.load(gep)
                 field_type = metadata.field_type(attr_name)